Publications by authors named "Susan Marquez"

7 Publications

  • Page 1 of 1

Phosphorylation of ACTN4 Leads to Podocyte Vulnerability and Proteinuric Glomerulosclerosis.

J Am Soc Nephrol 2020 07 15;31(7):1479-1495. Epub 2020 Jun 15.

Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts

Background: Genetic mutations in -actinin-4 (ACTN4)-an important actin crosslinking cytoskeletal protein that provides structural support for kidney podocytes-have been linked to proteinuric glomerulosclerosis in humans. However, the effect of post-translational modifications of ACTN4 on podocyte integrity and kidney function is not known.

Methods: Using mass spectrometry, we found that ACTN4 is phosphorylated at serine (S) 159 in human podocytes. We used phosphomimetic and nonphosphorylatable ACTN4 to comprehensively study the effects of this phosphorylation and . We conducted x-ray crystallography, F-actin binding and bundling assays, and immunofluorescence staining to evaluate F-actin alignment. Microfluidic organ-on-a-chip technology was used to assess for detachment of podocytes simultaneously exposed to fluid flow and cyclic strain. We then used CRISPR/Cas9 to generate mouse models and assessed for renal injury by measuring albuminuria and examining kidney histology. We also performed targeted mass spectrometry to determine whether high extracellular glucose or TGF- levels increase phosphorylation of ACTN4.

Results: Compared with the wild type ACTN4, phosphomimetic ACTN4 demonstrated increased binding and bundling activity with F-actin . Phosphomimetic Actn4 mouse podocytes exhibited more spatially correlated F-actin alignment and a higher rate of detachment under mechanical stress. Phosphomimetic Actn4 mice developed proteinuria and glomerulosclerosis after subtotal nephrectomy. Moreover, we found that exposure to high extracellular glucose or TGF- stimulates phosphorylation of ACTN4 at S159 in podocytes.

Conclusions: These findings suggest that increased phosphorylation of ACTN4 at S159 leads to biochemical, cellular, and renal pathology that is similar to pathology resulting from human disease-causing mutations in ACTN4. ACTN4 may mediate podocyte injury as a consequence of both genetic mutations and signaling events that modulate phosphorylation.
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http://dx.doi.org/10.1681/ASN.2019101032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351002PMC
July 2020

Quantitative prediction of human pharmacokinetic responses to drugs via fluidically coupled vascularized organ chips.

Nat Biomed Eng 2020 04 27;4(4):421-436. Epub 2020 Jan 27.

Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.

Analyses of drug pharmacokinetics (PKs) and pharmacodynamics (PDs) performed in animals are often not predictive of drug PKs and PDs in humans, and in vitro PK and PD modelling does not provide quantitative PK parameters. Here, we show that physiological PK modelling of first-pass drug absorption, metabolism and excretion in humans-using computationally scaled data from multiple fluidically linked two-channel organ chips-predicts PK parameters for orally administered nicotine (using gut, liver and kidney chips) and for intravenously injected cisplatin (using coupled bone marrow, liver and kidney chips). The chips are linked through sequential robotic liquid transfers of a common blood substitute by their endothelium-lined channels (as reported by Novak et al. in an associated Article) and share an arteriovenous fluid-mixing reservoir. We also show that predictions of cisplatin PDs match previously reported patient data. The quantitative in-vitro-to-in-vivo translation of PK and PD parameters and the prediction of drug absorption, distribution, metabolism, excretion and toxicity through fluidically coupled organ chips may improve the design of drug-administration regimens for phase-I clinical trials.
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http://dx.doi.org/10.1038/s41551-019-0498-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8011576PMC
April 2020

Robotic fluidic coupling and interrogation of multiple vascularized organ chips.

Nat Biomed Eng 2020 04 27;4(4):407-420. Epub 2020 Jan 27.

Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA, USA.

Organ chips can recapitulate organ-level (patho)physiology, yet pharmacokinetic and pharmacodynamic analyses require multi-organ systems linked by vascular perfusion. Here, we describe an 'interrogator' that employs liquid-handling robotics, custom software and an integrated mobile microscope for the automated culture, perfusion, medium addition, fluidic linking, sample collection and in situ microscopy imaging of up to ten organ chips inside a standard tissue-culture incubator. The robotic interrogator maintained the viability and organ-specific functions of eight vascularized, two-channel organ chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier and brain) for 3 weeks in culture when intermittently fluidically coupled via a common blood substitute through their reservoirs of medium and endothelium-lined vascular channels. We used the robotic interrogator and a physiological multicompartmental reduced-order model of the experimental system to quantitatively predict the distribution of an inulin tracer perfused through the multi-organ human-body-on-chips. The automated culture system enables the imaging of cells in the organ chips and the repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling.
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http://dx.doi.org/10.1038/s41551-019-0497-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8057865PMC
April 2020

On-chip recapitulation of clinical bone marrow toxicities and patient-specific pathophysiology.

Nat Biomed Eng 2020 04 27;4(4):394-406. Epub 2020 Jan 27.

Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.

The inaccessibility of living bone marrow (BM) hampers the study of its pathophysiology under myelotoxic stress induced by drugs, radiation or genetic mutations. Here, we show that a vascularized human BM-on-a-chip (BM chip) supports the differentiation and maturation of multiple blood cell lineages over 4 weeks while improving CD34 cell maintenance, and that it recapitulates aspects of BM injury, including myeloerythroid toxicity after clinically relevant exposures to chemotherapeutic drugs and ionizing radiation, as well as BM recovery after drug-induced myelosuppression. The chip comprises a fluidic channel filled with a fibrin gel in which CD34 cells and BM-derived stromal cells are co-cultured, a parallel channel lined by human vascular endothelium and perfused with culture medium, and a porous membrane separating the two channels. We also show that BM chips containing cells from patients with the rare genetic disorder Shwachman-Diamond syndrome reproduced key haematopoietic defects and led to the discovery of a neutrophil maturation abnormality. As an in vitro model of haematopoietic dysfunction, the BM chip may serve as a human-specific alternative to animal testing for the study of BM pathophysiology.
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http://dx.doi.org/10.1038/s41551-019-0495-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7160021PMC
April 2020

Osteoporosis Knowledge and Health Beliefs Among Men in Midlife Years.

J Nutr Educ Behav 2017 10 24;49(9):759-763.e1. Epub 2017 Jun 24.

Department of Human Development and Family Science, College of Health and Human Performance, East Carolina University, Greenville, NC.

Objective: To examine the role of socioeconomic variables on middle-aged adult men's knowledge and health beliefs about osteoporosis.

Methods: An anonymous survey used validated scales to assess osteoporosis knowledge and health beliefs in a sample of 262 men aged 36-55 years. Descriptive and group-differences statistics (MANOVA and ANOVA) were used.

Results: Total osteoporosis knowledge was low (mean, 11.1 of 22) and mean scores on perceived susceptibility and seriousness health belief domains were also low: 13.2 and 17.2, respectively out of 30. Multivariate ANOVA revealed that perceived seriousness, barriers to calcium intake, and health motivation varied significantly with level of formal education attained (P < .05). There was no significant difference with income.

Conclusions And Implications: Results of this convenience sample of predominantly white men found that level of osteoporosis knowledge and perceived susceptibility were low. Given the increased prevalence of osteoporosis-related fracture in men, methods to increase knowledge and awareness are needed.
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http://dx.doi.org/10.1016/j.jneb.2017.05.346DOI Listing
October 2017

The Health Benefits of Selected Culinary Herbs and Spices Found in the Traditional Mediterranean Diet.

Crit Rev Food Sci Nutr 2016 Dec;56(16):2728-46

a Division of Nutritional Sciences, Department of Food Science and Human Nutrition , University of Illinois Urbana-Champaign , Urbana , Illinois USA.

The Mediterranean diet is considered one of the healthiest diets in the world. This is often attributed to low saturated fat consumption, moderate wine consumption, and high vegetable consumption. However, herbs and spices associated with these diets may also play an important role in the quality of this diet. This review summarizes the most recent research regarding the anti-diabetic, anti-inflammatory, anti-hyperlipidemic and anti-hypertensive properties of this collection of culinary species. Additionally, this review briefly summarizes studies performed on lesser known herbs from around the world, with the goal of identifying new culinary species that may be useful in the treatment or prevention of diseases.
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http://dx.doi.org/10.1080/10408398.2013.805713DOI Listing
December 2016