Publications by authors named "Kristen Johnson"

148 Publications

Cysteine Mutations in the Ebolavirus Matrix Protein VP40 Promote Phosphatidylserine Binding by Increasing the Flexibility of a Lipid-Binding Loop.

Viruses 2021 07 15;13(7). Epub 2021 Jul 15.

Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.

Ebolavirus (EBOV) is a negative-sense RNA virus that causes severe hemorrhagic fever in humans. The matrix protein VP40 facilitates viral budding by binding to lipids in the host cell plasma membrane and driving the formation of filamentous, pleomorphic virus particles. The C-terminal domain of VP40 contains two highly-conserved cysteine residues at positions 311 and 314, but their role in the viral life cycle is unknown. We therefore investigated the properties of VP40 mutants in which the conserved cysteine residues were replaced with alanine. The C311A mutation significantly increased the affinity of VP40 for membranes containing phosphatidylserine (PS), resulting in the assembly of longer virus-like particles (VLPs) compared to wild-type VP40. The C314A mutation also increased the affinity of VP40 for membranes containing PS, albeit to a lesser degree than C311A. The double mutant behaved in a similar manner to the individual mutants. Computer modeling revealed that both cysteine residues restrain a loop segment containing lysine residues that interact with the plasma membrane, but Cys has the dominant role. Accordingly, the C311A mutation increases the flexibility of this membrane-binding loop, changes the profile of hydrogen bonding within VP40 and therefore binds to PS with greater affinity. This is the first evidence that mutations in VP40 can increase its affinity for biological membranes and modify the length of Ebola VLPs. The Cys and Cys residues therefore play an important role in dynamic interactions at the plasma membrane by modulating the ability of VP40 to bind PS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/v13071375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8310056PMC
July 2021

Discovery of Potent Coumarin-Based Kinetic Stabilizers of Amyloidogenic Immunoglobulin Light Chains Using Structure-Based Design.

J Med Chem 2021 05 3;64(9):6273-6299. Epub 2021 May 3.

Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States.

In immunoglobulin light-chain (LC) amyloidosis, transient unfolding or unfolding and proteolysis enable aggregation of LC proteins, causing potentially fatal organ damage. A drug that kinetically stabilizes LCs could suppress aggregation; however, LC sequences are variable and have no natural ligands, hindering drug development efforts. We previously identified high-throughput screening hits that bind to a site at the interface between the two variable domains of the LC homodimer. We hypothesized that extending the stabilizers beyond this initially characterized binding site would improve affinity. Here, using protease sensitivity assays, we identified stabilizers that can be divided into four substructures. Some stabilizers exhibit nanomolar EC values, a 3000-fold enhancement over the screening hits. Crystal structures reveal a key π-π stacking interaction with a conserved tyrosine residue that was not utilized by the screening hits. These data provide a foundation for developing LC stabilizers with improved binding selectivity and enhanced physicochemical properties.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.1c00339DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8428256PMC
May 2021

Evidence-Based Alignment of Pathology Residency With Practice II: Findings and Implications.

Acad Pathol 2021 Jan-Dec;8:23742895211002816. Epub 2021 Apr 7.

Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.

This article presents findings from a 4-year series of surveys of new-in-practice pathologists, and a survey of physician employers of new pathologists, assessing how pathology graduate medical education prepares its graduates for practice. Using the methodology described in our previous study, we develop evidence for the importance of residency training for various practice areas, comparing findings over different practice settings, sizes, and lengths of time in practice. The principal findings are (1) while new-in-practice pathologists and their employers report residency generally prepared them well for practice, some areas-billing and coding, laboratory management, molecular pathology, and pathology informatics-consistently were identified as being important in practice but inadequately prepared for in residency; (2) other areas-autopsy pathology, and subspecialized apheresis and blood donor center blood banking services-consistently were identified as relatively unimportant in practice and excessively prepared for in residency; (3) the notion of a single comprehensive model for categorical training in residency is challenged by the disparity between broad general practice in some settings and narrower subspecialty practice in others; and (4) the need for preparation in some areas evolves during practice, raising questions about the appropriate mode and circumstance for training in these areas. The implications of these findings range from rebalancing the emphasis among practice areas in residency, to reconsidering the structure of graduate medical education in pathology to meet present and evolving future practice needs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/23742895211002816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040604PMC
April 2021

The use of anthrolysin O and ostreolysin A to study cholesterol in cell membranes.

Methods Enzymol 2021 16;649:543-566. Epub 2021 Feb 16.

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, United States. Electronic address:

Cholesterol is a major component of the plasma membranes (PMs) of animal cells, comprising 35-40mol% of total PM lipids. Recent studies using cholesterol-binding bacterial toxins such as domain 4 of Anthrolysin O (ALOD4) and fungal toxins such as Ostreolysin A (OlyA) have revealed new insights into the organization of PM cholesterol. These studies have defined three distinct pools of PM cholesterol-a fixed pool that is essential for membrane integrity, a sphingomyelin (SM)-sequestered pool that can be detected by OlyA, and a third pool that is accessible and can be detected by ALOD4. Accessible cholesterol is available to interact with proteins and transport to the endoplasmic reticulum (ER), and controls many cellular signaling processes including cholesterol homeostasis, Hedgehog signaling, and bacterial and viral infection. Here, we provide detailed descriptions for the use of ALOD4 and OlyA, both of which are soluble and non-lytic proteins, to study cholesterol organization in the PMs of animal cells. Furthermore, we describe two new versions of ALOD4 that we have developed to increase the versatility of this probe in cellular studies. One is a dual His and FLAG epitope-tagged version and the other is a fluorescent version where ALOD4 is fused to Neon, a monomeric fluorescent protein. These new forms of ALOD4 together with previously described OlyA provide an expanded collection of tools to sense, visualize, and modulate levels of accessible and SM-sequestered cholesterol on PMs and study the role of these cholesterol pools in diverse membrane signaling events.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/bs.mie.2021.01.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034815PMC
June 2021

Health care resource utilization and disease modifying treatment use in multiple sclerosis patients by age and insurance type.

Curr Med Res Opin 2021 04 26;37(4):597-604. Epub 2021 Feb 26.

Novartis Pharmaceuticals Corporation, NJ, USA.

Objective: The objective of this study was to describe and compare health care resource utilization (HCRU) and disease modifying treatment (DMT) use among US adults <65 years with multiple sclerosis (MS), across commercial and Medicare Advantage plans.

Methods: Medical and pharmacy claims data from commercial and Medicare Advantage with Part D (MAPD) plans were extracted for MS patients age 18 - 64 identified between 1 January 2014 and 31 May 2017. Comparisons were made between commercial and MAPD enrollees for all-cause HCRU and DMT use over 1 year, overall and by 5 year age groups.

Results: A total of 28,427 MS patients were identified; two-thirds (67%) had commercial coverage. MAPD patients had statistically significantly higher mean counts of all-cause inpatient, emergency room (ER) and ambulatory visits compared to commercial patients. The significant differences were evident in all age groups ≥30 years, except for ER visits in the 40-44 and 60-64 age groups. MAPD patients had statistically significantly lower prevalence of DMT use compared to commercial patients in all age groups starting at ≥35 years.

Conclusion: MAPD patients had a higher burden of medical HCRU compared to their commercially insured counterparts, most likely due primarily to their more advanced disease state and higher level of MS-related disability. Reasons for lower prevalence of DMT use among MAPD patients may include their more advanced disease state, older age and higher prevalence of comorbid conditions compared with commercially insured patients, as well as more restrictive formularies for MAPD vs. commercial plans. These findings suggest that there may be an opportunity for recently approved DMTs indicated for active secondary progressive MS to fulfill an unmet need for treatment among MS patients <65 years without contraindicated comorbid conditions who are enrolled in MAPD plans. Novel therapies under development to delay progression may help keep MS patients of working age in the work force.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/03007995.2021.1885367DOI Listing
April 2021

Positive Job Search Experience for New Pathologists Seeking First Employment Between 2017 and 2019.

Arch Pathol Lab Med 2021 09;145(9):1117-1122

The Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee (Hoffman).

Context.—: An aging population calls for an adequate response in the workforce of medical professionals. The field of pathology has seen a downward trend in numbers of graduating US allopathic medical students choosing the specialty. Concerns about the job market after residency and fellowship graduation may be a contributing factor.

Objective.—: To provide an update on the trends emerging from a survey of pathology graduates' job search experience for their first nonfellowship position.

Design.—: Data from an annual job search survey sent by the College of American Pathologists Graduate Medical Education Committee between 2017 and 2019 to College of American Pathologists junior members and fellows in practice 3 years or less actively looking for a nonfellowship position was analyzed. Various indicators of the job search experience were compared year to year and with the previously published 2012 to 2016 benchmark data.

Results.—: Analysis revealed positive trends between the 2017 to 2019 data and the 2012 to 2016 benchmark data, including participants' perceiving more ease in finding a position, improved availability of jobs in their subspecialty choice, and higher ratings of satisfaction with the position accepted, as well as a greater proportion of respondents finding a position within 6 months of initiating their job search.

Conclusions.—: The job market for pathology residents and fellows looking for their first nonfellowship position has improved with respect to multiple indicators, such as ease of finding a position, length of job search, and satisfaction with the position accepted when comparing 2017 to 2019 data with the 2012 to 2016 benchmark data.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5858/arpa.2020-0455-CPDOI Listing
September 2021

Safety, Tolerability, and Pharmacokinetics of PF-06823859, an Anti-Interferon β Monoclonal Antibody: A Randomized, Phase I, Single- and Multiple-Ascending-Dose Study.

Clin Pharmacol Drug Dev 2021 03 22;10(3):307-316. Epub 2020 Dec 22.

Pfizer Clinical Research Unit, New Haven, Connecticut, USA.

This double-blind, randomized, placebo-controlled, dose-ascending, first-in-human study (NCT02766621) assessed the safety, tolerability, and pharmacokinetics (PK) of PF-06823859, an anti-interferon β monoclonal antibody. Healthy subjects were randomized to single ascending doses (SADs) of intravenous PF-06823859 30, 100, 300, 900, or 2000 mg or placebo; to multiple ascending doses (MADs) of subcutaneous PF-06823859 100 or 300 mg or placebo (once every 2 weeks for a total of 3 doses); or to MAD of intravenous PF-06823859 600 mg or placebo (once every 3 weeks or once every 4 weeks for a total of 2 doses). The incidence, severity, and causal relationship of adverse events (AEs) were assessed, along with immunogenicity and PK. In total, 62 subjects were randomized to treatment (SAD, n = 35; MAD, n = 27). There were 76 treatment-emergent all-causality AEs in the SAD (PF-06823859: n = 25; placebo: n = 4) and MAD (PF-06823859: n = 40; placebo: n = 7) cohorts. In the SAD cohorts, all treatment-emergent all-causality AEs were mild in severity; 4 AEs of moderate severity were identified in the MAD cohorts. No dose-limiting AEs, serious AEs, treatment-related discontinuations, dose reductions, or deaths occurred. PF-06823859 exposure increased dose-proportionally, with half-life values ranging between 23 and 35 days. The estimated subcutaneous bioavailability was 43% to 44%. Immunogenicity incidence rates were low (antidrug antibodies, 12.5%; neutralizing antibodies, 2.1%). No immunogenically related clinical responses of concern were observed. In conclusion, PF-06823859 demonstrated an acceptable safety, tolerability, and PK profile that supports clinical development for treating disorders associated with increased interferon β levels, such as dermatomyositis or systemic lupus erythematosus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cpdd.887DOI Listing
March 2021

Identifying disability level in multiple sclerosis patients in a U.S.-based health plan claims database.

J Med Econ 2021 Jan-Dec;24(1):46-53

Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA.

Aims: In clinical trials, disability progression in multiple sclerosis (MS) is measured by the Kurtzke expanded disability status scale (EDSS), which is not captured in routine clinical care in the U.S. This study developed a claims-based disability score (CDS) based on the EDSS for assigning MS disability level in a U.S. claims database.

Methods: This retrospective cohort study of patients with MS in the U.S., utilized adjudicated health plan claims data linked to electronic medical records (EMRs) data. Patients were identified between 1 January 2012 and 31 December 2016 and indexed on the first date of MS diagnosis. The CDS was developed to assign disability level at baseline using claims and ambulatory EMR records observed over the 1-year baseline period. All-cause healthcare costs were assessed by baseline disability level to validate the CDS.

Results: In total, 45,687 patients were identified in claims (full sample) and 1,599 linked to EMR (core sample). Over half of patients in both samples were classified with mild disability at baseline. Adjusted healthcare costs in patients with moderate and severe disability were 15% (<.0001) and 20% higher, respectively, than in patients with mild disability at baseline in the full sample. Disease-modifying therapy (DMT) costs accounted for 89%, 82%, and 78% of outpatient pharmacy costs in patients with mild, moderate, and severe disability, respectively.

Conclusions: The CDS is the first claims-based measure of MS disability utilizing data from EMR. This novel measure advances the opportunity to examine outcomes by disability accumulation in the absence of standard markers of disease progression. Although formal validation of the CDS was not possible due to lack of available EDSS in the EMR, the economic burden results align with prior publications and show that healthcare costs increase with increasing disability. Future validation studies of the CDS are warranted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/13696998.2020.1857257DOI Listing
December 2020

Effect of Different Forms of Activity-Based Recovery Training on Bladder, Bowel, and Sexual Function After Spinal Cord Injury.

Arch Phys Med Rehabil 2021 05 3;102(5):865-873. Epub 2020 Dec 3.

Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY; Department of Neurological Surgery, University of Louisville, Louisville, KY.

Objectives: To investigate whether the urogenital and bowel functional gains previously demonstrated post-locomotor step training after chronic spinal cord injury could have been derived due to weight-bearing alone or from exercise in general.

Design: Prospective cohort study; pilot trial with small sample size.

Setting: Urogenital and bowel scientific core facility at a rehabilitation institute and spinal cord injury research center in the United States.

Participants: Men and women (N=22) with spinal cord injury (American Spinal Injury Association Impairment Scale grades of A-D) participated in this study.

Interventions: Approximately 80 daily 1-hour sessions of either stand training or nonweight-bearing arm crank ergometry. Comparisons were made with previously published locomotor training data (step; N=7).

Main Outcome Measures: Assessments at both pre- and post-training timepoints included cystometry for bladder function and International Data Set Questionnaires for bowel and sexual functions.

Results: Cystometry measurements revealed a significant decrease in bladder pressure and limited improvement in compliance with nonweight-bearing exercise but not with standing. Although International Data Set questionnaires revealed profound bowel dysfunction and marked deficits in sexual function pretraining, no differences were identified poststand or after nonweight-bearing exercise.

Conclusions: These pilot trial results suggest that, although stand and weight-bearing alone do not benefit pelvic organ functions after spinal cord injury, exercise in general may contribute at least partially to the lowering of bladder pressure and the increase in compliance that was seen previously with locomotor training, potentially through metabolic, humoral, and/or cardiovascular mechanisms. Thus, to maximize activity-based recovery training benefits for functions related to storage and emptying, an appropriate level of sensory input to the spinal cord neural circuitries controlling bladder and bowel requires task-specific stepping.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.apmr.2020.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8084981PMC
May 2021

Comparison of diagnosis and prescribing practices between virtual visits and office visits for adults diagnosed with uncomplicated urinary tract infections within a primary care network.

Infect Control Hosp Epidemiol 2021 05 29;42(5):586-591. Epub 2020 Oct 29.

Division of Infectious Diseases, Mercy Health Saint Mary's, Grand Rapids, Michigan.

Objectives: Telemedicine visits are an increasingly popular method of care for mild infectious complaints, including uncomplicated urinary tract infections (UTIs), and they are an important target for antimicrobial stewardship programs (ASPs) to evaluate quality of prescribing. In this study, we compared antimicrobial prescribing in a primary care network for uncomplicated UTIs treated through virtual visits and at in-office visits.

Design: Retrospective cohort study comparing guideline-concordant antibiotic prescribing for uncomplicated UTI between virtual visits and office visits.

Setting: Primary care network composed of 44 outpatient sites and a single virtual visit platform.

Patients: Adult female patients diagnosed with a UTI between January 1 and December 31, 2018.

Methods: Virtual visit prescribing was compared to office visit prescribing, including agent, duration, and patient outcomes. The health system ASP provides annual education to all outpatient providers regarding local antibiogram trends and prescribing guidelines. Guideline-concordant therapy was assessed based on the network's ASP guidelines.

Results: In total, 350 patients were included, with 175 per group. Patients treated for a UTI through a virtual visit were more likely to receive a first-line antibiotic agent (74.9% vs 59.4%; P = .002) and guideline-concordant duration (100% vs 53.1%; P < .001). Patients treated through virtual visits were also less likely to have a urinalysis (0% vs 97.1%; P < .001) or urine culture (0% vs 73.1%; P < .001) ordered and were less likely to revisit within 7 days (5.1% vs 18.9%; P < .001).

Conclusions: UTI care through a virtual visit was associated with more appropriate antimicrobial prescribing compared to office visits and decreased utilization of diagnostic and follow-up resources.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1017/ice.2020.1255DOI Listing
May 2021

Factors Influencing US Allopathic Medical Students to Choose Pathology as a Specialty.

Acad Pathol 2020 Jan-Dec;7:2374289520951924. Epub 2020 Sep 14.

Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.

The SARS-CoV-2 pandemic has highlighted the crucial role of pathologists in the health care system at a time of significant decline in the number of US medical students matching to pathology residency positions. To understand this decline, a national survey of fourth-year US allopathic medical students was conducted to assess experiences, knowledge, and attitudes of pathology and factors that impact specialty choice. Participating in a separate pathology course did not increase the probability of choosing pathology. Experiences significantly associated with choosing pathology included clinical or research opportunities in pathology during the last 2 years of medical school, autopsy observation/participation, and participation in pathology interest groups. Many respondents felt they were not sufficiently exposed to pathology to consider it as a specialty. Those who considered pathology but did not choose it were less likely to report understanding the activities of pathologists and being recruited by pathology faculty and more likely to express a preference for more direct patient contact as compared to those entering pathology. In general, respondents agreed that pathology has a good work-life balance and a satisfying degree of intellectual challenge. On the other hand, respondents generally agreed that information on social media and perception of the pathology job market do not seem to be positive and few agreed that pathology is a highly regarded specialty. We identify steps to address these issues and increase the number of US medical students choosing pathology as a specialty crucial to the future of medicine and public health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/2374289520951924DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7557358PMC
September 2020

Quantifying reversible nitrogenous ligand binding to Co(ii) porphyrin receptors at the solution/solid interface and in solution.

Phys Chem Chem Phys 2020 Nov 21;22(42):24226-24235. Epub 2020 Oct 21.

Department of Chemistry and Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164-4630, USA.

We present a quantitative study comparing the binding of 4-methoxypyridine, MeOPy, ligand to Co(ii)octaethylporphyrin, CoOEP, at the phenyloctane/HOPG interface and in toluene solution. Scanning tunneling microscopy (STM) was used to study the ligand binding to the porphyrin receptors adsorbed on graphite. Electronic spectroscopy was employed for examining this process in fluid solution. The on surface coordination reaction was completely reversible and followed a simple Langmuir adsorption isotherm. Ligand affinities (or ΔG) for the binding processes in the two different chemical environments were determined from the respective equilibrium constants. The free energy value of -13.0 ± 0.3 kJ mol for the ligation reaction of MeOPy to CoOEP at the solution/HOPG interface is less negative than the ΔG for cobalt porphyrin complexed to the ligand in solution, -16.8 ± 0.2 kJ mol. This result indicates that the MeOPy-CoOEP complex is more stable in solution than on the surface. Additional thermodynamic values for the formation of the surface ligated species (ΔH = -50 kJ mol and ΔS = -120 J mol) were extracted from temperature dependent STM measurements. Density functional computational methods were also employed to explore the energetics of both the solution and surface reactions. At high concentrations of MeOPy the monolayer was observed to be stripped from the surface. Computational results indicate that this is not because of a reduction in adsorption energy of the MeOPy-CoOEP complex. Nearest neighbor analysis of the MeOPy-CoOEP in the STM images revealed positive cooperative ligand binding behavior. Our studies bring new insights to the general principles of affinity and cooperativity in the ligand-receptor interactions at the solution/solid interface. Future applications of STM will pave the way for new strategies designing highly functional multisite receptor systems for sensing, catalysis, and pharmacological applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0cp04109bDOI Listing
November 2020

Implementing outpatient antimicrobial stewardship in a primary care office through ambulatory care pharmacist-led audit and feedback.

J Am Pharm Assoc (2003) 2020 Nov - Dec;60(6):e246-e251. Epub 2020 Aug 26.

Objectives: This study aimed to determine the impact of a pharmacist-led antimicrobial stewardship program (ASP) intervention on outpatient antibiotic prescribing for upper respiratory tract infections (URIs) and urinary tract infections (UTIs) in a primary care office. The primary outcome of this study was to characterize antibiotic prescribing over time. Secondary outcomes included describing ambulatory care pharmacist (ACP) workload and types of feedback given.

Methods: A retrospective pilot study was conducted within a primary care office. The office included a 0.6 full-time equivalent ACP and is part of a health system supported by a pharmacist and a physician co-led ASP. Education and guidelines were provided by the ACP and ASP leads before the intervention period August 2017-February 2018. The ACP provided bi-weekly audit of all URI and UTI prescriptions and written feedback to prescribers.

Results: During the 7-month intervention period, 1107 prescriptions were audited by the ACP, 825 URI and 282 UTI. The most common reasons for feedback included inappropriate agent (26.3%) or prolonged duration of therapy (24.3%). Guideline-concordant agent prescribed for a UTI increased from 20% at baseline to a median of 69.2%, whereas duration increased from 55% to 70.4%. Guideline-concordant agent prescribed for a URI increased from 43.3% to 86.8%, whereas the median duration of therapy decreased from 10 to 7 days.

Conclusion: An ACP-led ASP intervention within a primary care office incorporating audit and feedback improved antibiotic prescribing for URIs and UTIs, including prescribing antibiotics when indicated, guideline-concordant antibiotic selection, and duration of therapy. Pharmacists practicing in ambulatory care settings may serve a vital role in leading successful outpatient ASP interventions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.japh.2020.08.003DOI Listing
June 2021

Antitumor activity of a systemic STING-activating non-nucleotide cGAMP mimetic.

Science 2020 Aug;369(6506):993-999

Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

Stimulator of interferon genes (STING) links innate immunity to biological processes ranging from antitumor immunity to microbiome homeostasis. Mechanistic understanding of the anticancer potential for STING receptor activation is currently limited by metabolic instability of the natural cyclic dinucleotide (CDN) ligands. From a pathway-targeted cell-based screen, we identified a non-nucleotide, small-molecule STING agonist, termed SR-717, that demonstrates broad interspecies and interallelic specificity. A 1.8-angstrom cocrystal structure revealed that SR-717 functions as a direct cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) mimetic that induces the same "closed" conformation of STING. SR-717 displayed antitumor activity; promoted the activation of CD8 T, natural killer, and dendritic cells in relevant tissues; and facilitated antigen cross-priming. SR-717 also induced the expression of clinically relevant targets, including programmed cell death 1 ligand 1 (PD-L1), in a STING-dependent manner.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/science.abb4255DOI Listing
August 2020

The future of animal science departments.

Anim Front 2020 Jul 23;10(3):4-5. Epub 2020 Jul 23.

Department of Animal Science, Washington University, Pullman, WA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/af/vfaa020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7377513PMC
July 2020

Patient reported outcomes and performance metrics at diagnosis of secondary progressive multiple sclerosis.

Mult Scler 2021 04 16;27(5):742-754. Epub 2020 Jul 16.

Mellen Center for Multiple Sclerosis Treatment and Research, Neurological Institute, Cleveland Clinic Foundation, Cleveland, OH, USA.

Background: Relapsing-remitting multiple sclerosis (RRMS) usually evolves into secondary progressive multiple sclerosis (SPMS). Recognition of SPMS is important because of prognostic and treatment implications.

Objective: The objective of this study is to determine distributions of patient-reported outcomes (PROs) and the Timed 25-Foot Walk (T25FW) at SPMS diagnosis and describe the evolution of these metrics in patients with SPMS.

Methods: A tertiary MS center clinical database was queried to identify patients with RRMS and SPMS. PRO data including performance scales (PS), Patient Health Questionnaire-9 (PHQ-9), European Quality of Life-5-Dimensions (EQ-5D), and the T25FW were extracted. Descriptive statistics were calculated at SPMS diagnosis, and score trajectories were modeled. Cox proportional hazards modeling was used to estimate hazard ratios for time to SPMS diagnosis.

Results: Among 5,558 patients identified, 164 were diagnosed with SPMS between January 2008 and June 2016. At SPMS diagnosis, the mean outcome values were T25FW = 12.5 seconds (standard deviation, SD = 10.7), PS = 15.6 (SD = 6.5), PHQ-9 = 6.8 (SD = 4.2), and EQ-5D = 0.63 (SD = 0.20). Distinct patterns were observed in the measures leading up to SPMS diagnosis. Higher age, male gender, longer disease duration, and greater disability were associated with an increased hazard of SPMS diagnosis.

Conclusion: Longitudinal monitoring of PROs and performance metrics may help identify those at higher risk of near-term SPMS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1352458520936214DOI Listing
April 2021

Accessible cholesterol is localized in bacterial plasma membrane protrusions.

J Lipid Res 2020 12 13;61(12):1538. Epub 2020 Jul 13.

Departments of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1194/jlr.ILR120000891DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7707182PMC
December 2020

Pain in Patients With Type 2 Diabetes-Related Polyneuropathy Is Associated With Vascular Events and Mortality.

J Clin Endocrinol Metab 2020 09;105(9)

Department of Neurology/Neuromuscular Center, Neurological Institute, Cleveland Clinic, Cleveland, Ohio.

Purpose: Type 2 diabetes-related polyneuropathy (DPN) is associated with increased vascular events and mortality, but determinants and outcomes of pain in DPN are poorly understood. We sought to examine the effect of neuropathic pain on vascular events and mortality in patients without DPN, DPN with pain (DPN + P), and DPN without pain (DPN-P).

Methods: A retrospective cohort study was conducted within a large health system of adult patients with type 2 diabetes from January 1, 2009 through December 31, 2016. Using an electronic algorithm, patients were classified as no DPN, DPN + P, or DPN-P. Primary outcomes included number of vascular events and time to mortality. Independent associations with DPN + P were evaluated using multivariable negative binomial and Cox proportional hazards regression models, adjusting for demographics, socioeconomic characteristics, and comorbidities.

Results: Of 43 945 patients with type 2 diabetes (age 64.6 ± 14.0 years; 52.1% female), 13 910 (31.7%) had DPN: 9104 DPN + P (65.4%) vs 4806 DPN-P (34.6%). Vascular events occurred in 4538 (15.1%) of no DPN patients, 2401 (26.4%) DPN + P, and 1006 (20.9%) DPN-P. After adjustment, DPN + P remained a significant predictor of number of vascular events (incidence rate ratio [IRR] = 1.55, 95% CI, 1.29-1.85), whereas no DPN was protective (IRR = 0.70, 95% CI, 0.60-0.82), as compared to DPN-P. Compared to DPN-P, DPN + P was also a significant predictor of mortality (hazard ratio = 1.42, 95% CI, 1.25-1.61).

Conclusions: Our study found a significant association between pain in DPN and an increased risk of vascular events and mortality. This observation warrants longitudinal study of the risk factors and natural history of pain in DPN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1210/clinem/dgaa394DOI Listing
September 2020

A Conserved Tryptophan in the Ebola Virus Matrix Protein C-Terminal Domain Is Required for Efficient Virus-Like Particle Formation.

Pathogens 2020 May 22;9(5). Epub 2020 May 22.

Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Institute for Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.

The Ebola virus (EBOV) harbors seven genes, one of which is the matrix protein eVP40, a peripheral protein that is sufficient to induce the formation of virus-like particles from the host cell plasma membrane. eVP40 can form different structures to fulfil different functions during the viral life cycle, although the structural dynamics of eVP40 that warrant dimer, hexamer, and octamer formation are still poorly understood. eVP40 has two conserved Trp residues at positions 95 and 191. The role of Trp has been characterized in depth as it serves as an important residue in eVP40 oligomer formation. To gain insight into the functional role of Trp in eVP40, we prepared mutations of Trp (W191A or W191F) to determine the effects of mutation on eVP40 plasma membrane localization and budding as well as eVP40 oligomerization. These in vitro and cellular experiments were complemented by molecular dynamics simulations of the wild-type (WT) eVP40 structure versus that of W191A. Taken together, Trp is shown to be a critical amino acid at position 191 as mutation to Ala reduces the ability of VP40 to localize to the plasma membrane inner leaflet and form new virus-like particles. Further, mutation of Trp to Ala or Phe shifted the in vitro equilibrium to the octamer form by destabilizing Trp interactions with nearby residues. This study has shed new light on the importance of interdomain interactions in stability of the eVP40 structure and the critical nature of timing of eVP40 oligomerization for plasma membrane localization and viral budding.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/pathogens9050402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281420PMC
May 2020

State Licensing Board Requirements for Entry into the Dental Hygiene Profession.

J Dent Hyg 2020 Apr;94(2):54-65

The purpose of this study was to identify current requirements for initial licensure and entry into the dental hygiene profession across state dental and dental hygiene licensing boards in the United States. A non-experimental study design was used to study dental and dental hygiene board licensing requirements in the United States, Puerto Rico and the Virgin Islands. Each regulatory board website was searched for requirements for entry-level dental hygiene licensure. Requirements were recorded on an Excel spreadsheet. State dental practice acts were reviewed to gather further information and 20 regulatory bodies were contacted to verify accuracy. Descriptive statistics were used to analyze data. Information from a total of 52 dental boards (n=52) was examined for this study. Nearly all boards (n=51, 98.1%), with the exception of Alabama, required completion of entry-level education from a CODA accredited dental hygiene program and successful completion of the National Board Dental Hygiene Examination. Most states (n=51, 98.1%), except Delaware, also required a live-patient, a clinical board examination. Application fees ranged from $47.70 to $600. States varied considerably in terms of requirements for background checks, age, military status, and infection control training. Although the majority of regulatory bodies require completion of entry-level dental hygiene education from a CODA accredited program and successful completion of national board and a live-patient, clinical examination, there is considerable variation in other additional requirements for initial dental hygiene licensure.
View Article and Find Full Text PDF

Download full-text PDF

Source
April 2020

Managing COVID-19 in Renal Transplant Recipients: A Review of Recent Literature and Case Supporting Corticosteroid-sparing Immunosuppression.

Pharmacotherapy 2020 06 26;40(6):517-524. Epub 2020 May 26.

Department of Pharmacy Services, Mercy Health Saint Mary's, Grand Rapids, Michigan, USA.

Novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome virus (SARS-CoV-2) has become a global health care crisis. The Centers for Disease Control and Prevention (CDC) lists immunocompromised patients, including those requiring immunosuppression following renal transplantation, as high risk for severe disease from SARS-CoV-2. Treatment for other viral infections in renal transplant recipients often includes a reduction in immunosuppression; however, no current guidelines are available recommending the optimal approach to managing immunosuppression in the patients who are infected with SARS-CoV-2. It is currently advised to avoid corticosteroids in the treatment of SARS-CoV-2 outside of critically ill patients. Recently published cases describing inpatient care of COVID-19 in renal transplant recipients differ widely in disease severity, time from transplantation, baseline immunosuppressive therapy, and the modifications made to immunosuppression during COVID-19 treatment. This review summarizes and compares inpatient immunosuppressant management strategies of recently published reports in the renal transplant population infected with SARS-CoV-2 and discusses the limitations of corticosteroids in managing immunosuppression in this patient population.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/phar.2410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7267490PMC
June 2020

Accessibility of cholesterol at cell surfaces.

J Lipid Res 2020 10 23;61(10):1307. Epub 2020 Apr 23.

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1194/jlr.ILR120000836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7529053PMC
October 2020

Oxysterols provide innate immunity to bacterial infection by mobilizing cell surface accessible cholesterol.

Nat Microbiol 2020 07 13;5(7):929-942. Epub 2020 Apr 13.

Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.

Cholesterol 25-hydroxylase (CH25H) is an interferon-stimulated gene that converts cholesterol to the oxysterol 25-hydroxycholesterol (25HC). Circulating 25HC modulates essential immunological processes including antiviral immunity, inflammasome activation and antibody class switching; and dysregulation of CH25H may contribute to chronic inflammatory disease and cancer. Although 25HC is a potent regulator of cholesterol storage, uptake, efflux and biosynthesis, how these metabolic activities reprogram the immunological state of target cells remains poorly understood. Here, we used recently designed toxin-based biosensors that discriminate between distinct pools of plasma membrane cholesterol to elucidate how 25HC prevents Listeria monocytogenes from traversing the plasma membrane of infected host cells. The 25HC-mediated activation of acyl-CoA:cholesterol acyltransferase (ACAT) triggered rapid internalization of a biochemically defined fraction of cholesterol, termed 'accessible' cholesterol, from the plasma membrane while having little effect on cholesterol in complexes with sphingomyelin. We show that evolutionarily distinct bacterial species, L. monocytogenes and Shigella flexneri, exploit the accessible pool of cholesterol for infection and that acute mobilization of this pool by oxysterols confers immunity to these pathogens. The significance of this signal-mediated membrane remodelling pathway probably extends beyond host defence systems, as several other biologically active oxysterols also mobilize accessible cholesterol through an ACAT-dependent mechanism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41564-020-0701-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442315PMC
July 2020

Entry of Graduates of US Pathology Residency Programs Into the Workforce: Cohort Data Between 2008 and 2016 Remain Positive and Stable.

Acad Pathol 2020 Jan-Dec;7:2374289520901833. Epub 2020 Feb 6.

The Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.

The pathologist workforce in the United States is a topic of interest to the health-care community as a whole and to institutions responsible for the training of new pathologists in particular. Although a pathologist shortage has been projected, there has been a pervasive belief by medical students and their advisors that there are "no jobs in pathology." In 2013 and again in 2017, the Program Directors Section of the Association of Pathology Chairs conducted surveys asking pathology residency directors to report the employment status of each of their residents graduating in the previous 5 years. The 2013 Program Directors Section survey indicated that 92% of those graduating in 2010 had obtained employment within 3 years, and 94% of residents graduating in 2008 obtained employment within 5 years. The 2017 survey indicated that 96% of those graduating in 2014 had obtained employment in 3 years, and 97% of residents graduating in 2012 obtained positions within 5 years. These findings are consistent with residents doing 1 or 2 years of fellowship before obtaining employment. Stratification of the data by regions of the country or by the size of the residency programs does not show large differences. The data also indicate a high percentage of employment for graduates of pathology residency programs and a stable job market over the years covered by the surveys.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/2374289520901833DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005983PMC
February 2020

Molecular Analysis of Membrane Targeting by the C2 Domain of the E3 Ubiquitin Ligase Smurf1.

Biomolecules 2020 02 4;10(2). Epub 2020 Feb 4.

Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.

SMAD ubiquitination regulatory factor 1 (Smurf1) is a Nedd4 family E3 ubiquitin ligase that regulates cell motility, polarity and TGFβ signaling. Smurf1 contains an N-terminal protein kinase C conserved 2 (C2) domain that targets cell membranes and is required for interactions with membrane-localized substrates such as RhoA. Here, we investigated the lipid-binding mechanism of Smurf1 C2, revealing a general affinity for anionic membranes in addition to a selective affinity for phosphoinositides (PIPs). We found that Smurf1 C2 localizes not only to the plasma membrane but also to negatively charged intracellular sites, acting as an anionic charge sensor and selective PIP-binding domain. Site-directed mutagenesis combined with docking/molecular dynamics simulations revealed that the Smurf1 C2 domain loop region primarily interacts with PIPs and cell membranes, as opposed to the β-surface cationic patch employed by other C2 domains. By depleting PIPs from the inner leaflet of the plasma membrane, we found that PIP binding is necessary for plasma membrane localization. Finally, we used a Smurf1 cellular ubiquitination assay to show that the amount of ubiquitin at the plasma membrane interface depends on the lipid-binding properties of Smurf1. This study shows the mechanism by which Smurf1 C2 targets membrane-based substrates and reveals a novel interaction for non-calcium-dependent C2 domains and membrane lipids.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/biom10020229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7072158PMC
February 2020

Gender Parity in Gainful Employment and Other Gender Trends in the Job Market for Recent Pathology Graduates.

Arch Pathol Lab Med 2020 04 9;144(4):435-442. Epub 2019 Dec 9.

From the Department of Pathology, Virginia Commonwealth University School of Medicine, Richmond (Dr Shyu); Learning, College of American Pathologists, Northfield, Illinois (Dr Johnson); the Department of Pathology, Penn State Health Hershey Medical Center, Hershey, Pennsylvania (Dr George); the Department of Pathology, Stanford University School of Medicine, Stanford, California (Dr Gratzinger); The Joint Pathology Center, Silver Spring, Maryland (Dr Brissette); Walter Reed National Military Medical Center, Bethesda, Maryland (Dr Childs); the Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk (Dr Conran); the Department of Pathology, University of Central Florida College of Medicine, Orlando (Dr Dixon); the Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City (Dr McCloskey); the Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston (Dr Prieto); ProPath Associates, Dallas, Texas (Dr Roberts); the Department of Pathology, Augusta University-Medical College of Georgia, Augusta (Dr Rojiani); the Department of Pathology, Children's Medical Center of Dallas, Dallas, Texas (Dr Timmons Jr); and the Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee (Dr Hoffman).

Context.—: Gender-based barriers to equal salary, career advancement, and leadership still exist in medicine. Herein we provide the first report of data comparing the experiences of men and women seeking their first nonfellowship position in pathology.

Objective.—: To identify gender trends regarding pathologists taking their first job after training and the relationship to various demographic factors, job search satisfaction, and outcome.

Design.—: Aggregate data from the College of American Pathologists Graduate Medical Education Committee Job Market surveys (2015-2018) were analyzed across multiple domains including residency focus, number and subspecialty of fellowships completed, and extent to which expectations were met in regard to work duties, geographic preference, benefits, and salary. These data were examined in the context of assessing gender-based differences.

Results.—: Comparable results were identified in all measured outcomes according to gender. There were no differences between gender and medical school type, relocation, residency training focus, number of fellowships completed, overall satisfaction with position accepted, salary, or extent to which the position met expectations. Similarly, there were also no discrepancies between gender and the geographic region in which positions were accepted, practice setting, practice subspecialty, partnership track, length of job search, or difficulty finding a position.

Conclusions.—: Analysis from 4 years of job market survey data shows equivalent results between men and women looking for their first nonfellowship position in pathology. There were no significant differences with regard to difficulty finding a position, overall satisfaction with the position accepted, salary, benefits, or access to partnership track.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5858/arpa.2019-0354-CPDOI Listing
April 2020

Burden of relapsing-remitting multiple sclerosis on workers in the US: a cross-sectional analysis of survey data.

BMC Neurol 2019 Oct 28;19(1):258. Epub 2019 Oct 28.

Novartis Pharmaceuticals Corporation, One Health Plaza, East Hanover, NJ, 07936, USA.

Background: Multiple sclerosis (MS) is prevalent among working age individuals (20-60 years), leading to high burden on work productivity. Few data are available about the absenteeism and presenteeism in employed individuals with MS in comparison to non-MS personnel. This study aimed to quantify the burden of illness of employed US adults with relapsing-remitting multiple sclerosis (RRMS) and examine burden by levels of work impairment.

Methods: A retrospective cross-sectional analysis was conducted using patient-reported responses from the US National Health and Wellness Survey (NHWS). Data from NHWS 2015-2016 were analyzed from 196 employed RRMS respondents who were matched 1:4 to employed respondents without MS based on demographic and general health characteristics. Demographic and general health characteristics for employed RRMS individuals were analyzed by levels of work impairment (none, 1-30%; 31-68%; 69-100%). Work productivity (absenteeism, presenteeism, and work impairment), decrements in health-related quality of life (HRQoL) (short form-36, EQ-5D), and healthcare resource utilization (HCRU) were compared to determine the burden of RRMS.

Results: After propensity score matching, the levels of absenteeism and presenteeism were 2 and 1.8 times higher in the employed RRMS population than the employed non-MS population, respectively (P < 0.001 for both). HRQoL was significantly lower in employed respondents with RRMS than those without MS (P < 0.001 for all). Employed respondents with RRMS had significantly more HCRU over 6 months compared to those without MS (P < 0.001). Furthermore, among employed RRMS respondents, greater levels of impairment were associated with increasing disease severity, greater healthcare resource use, fatigue, and cognitive impairment and inversely associated with mental and physical HRQoL (P < 0.0001 for all).

Conclusions: Among employed individuals, respondents with RRMS had lower, work productivity, HRQoL, and higher HCRU as compared with those without MS. Given the large impact RRMS has on work impairment, a need exists to manage individuals on therapies that improve HRQoL, reduce symptoms, and improve their ability to perform in the workforce.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12883-019-1495-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6816180PMC
October 2019

Comparison of Diagnosis and Prescribing Practices Between Virtual Visits and Office Visits for Adults Diagnosed With Sinusitis Within a Primary Care Network.

Open Forum Infect Dis 2019 Sep 5;6(9):ofz393. Epub 2019 Oct 5.

Department of Infectious Diseases, Mercy Health Saint Mary's Grand Rapids, MI.

Background: Many antibiotics prescribed in the outpatient setting result from upper respiratory tract infections (URTIs); however, these infections are often viral. Virtual visits have emerged as a popular alternative to office visits for URTIs and may be an important target for antimicrobial stewardship programs.

Methods: This retrospective cohort study evaluated adult patients diagnosed with sinusitis treated within a single primary care network. The primary objective was to compare guideline-concordant diagnosis between patients treated via virtual visits vs in-office visits. Guideline-concordant bacterial sinusitis diagnosis was based on national guideline recommendations. Secondary objectives included comparing guideline-concordant antibiotic prescribing between groups and 24-hour, 7-day, and 30-day revisits.

Results: A total of 350 patients were included in the study, with 175 in each group. Patients treated for sinusitis were more likely to receive a guideline-concordant diagnosis in the virtual visit group (69.1% vs 45.7%; < .001). Additionally, patients who completed virtual visits were less likely to receive antibiotics (68.6% vs 94.3%; < .001). Guideline-concordant antibiotic selection was similar between groups (67.5% vs 64.8%; = .641). The median duration of therapy in both groups was 10 days ( = .88). Patients completing virtual visits were more likely to revisit for sinusitis within 24 hours (8% vs 1.7%; = .006) and within 30 days (14.9% vs 7.4%; = .027).

Conclusions: In adult patients presenting with sinusitis, care at a virtual visit was associated with an increase in guideline-concordant diagnosis and a decrease in antibiotic prescribing compared with in-office primary care visits. Virtual visit platforms may be a valuable tool for antimicrobial stewardship programs in the outpatient setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/ofid/ofz393DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6778270PMC
September 2019

Cholesterol accessibility at the ciliary membrane controls hedgehog signaling.

Elife 2019 10 30;8. Epub 2019 Oct 30.

Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.

Previously we proposed that transmission of the hedgehog signal across the plasma membrane by Smoothened is triggered by its interaction with cholesterol (Luchetti et al., 2016). But how is cholesterol, an abundant lipid, regulated tightly enough to control a signaling system that can cause birth defects and cancer? Using toxin-based sensors that distinguish between distinct pools of cholesterol, we find that Smoothened activation and Hedgehog signaling are driven by a biochemically-defined, small fraction of membrane cholesterol, termed accessible cholesterol. Increasing cholesterol accessibility by depletion of sphingomyelin, which sequesters cholesterol in complexes, amplifies Hedgehog signaling. Hedgehog ligands increase cholesterol accessibility in the membrane of the primary cilium by inactivating the transporter-like protein Patched 1. Trapping this accessible cholesterol blocks Hedgehog signal transmission across the membrane. Our work shows that the organization of cholesterol in the ciliary membrane can be modified by extracellular ligands to control the activity of cilia-localized signaling proteins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.50051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850779PMC
October 2019
-->