Publications by authors named "Jennifer Jiang"

14 Publications

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Integrating on-grid immunogold labeling and cryo-electron tomography to reveal photosystem II structure and spatial distribution in thylakoid membranes.

J Struct Biol 2021 May 16;213(3):107746. Epub 2021 May 16.

Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States; Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States. Electronic address:

A long-standing challenge in cell biology is elucidating the structure and spatial distribution of individual membrane-bound proteins, protein complexes and their interactions in their native environment. Here, we describe a workflow that combines on-grid immunogold labeling, followed by cryo-electron tomography (cryoET) imaging and structural analyses to identify and characterize the structure of photosystem II (PSII) complexes. Using an antibody specific to a core subunit of PSII, the D1 protein (uniquely found in the water splitting complex in all oxygenic photoautotrophs), we identified PSII complexes in biophysically active thylakoid membranes isolated from a model marine diatom Phaeodactylum tricornutum. Subsequent cryoET analyses of these protein complexes resolved two PSII structures: supercomplexes and dimeric cores. Our integrative approach establishes the structural signature of multimeric membrane protein complexes in their native environment and provides a pathway to elucidate their high-resolution structures.
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http://dx.doi.org/10.1016/j.jsb.2021.107746DOI Listing
May 2021

Structural insight into transmissive mutant huntingtin species by correlative light and electron microscopy and cryo-electron tomography.

Biochem Biophys Res Commun 2021 Jun 10;560:99-104. Epub 2021 May 10.

Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA; Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA. Electronic address:

Aggregates of mutant huntingtin (mHTT) containing an expanded polyglutamine (polyQ) tract are hallmarks of Huntington's Disease (HD). Studies have shown that mHTT can spread between cells, leading to the propagation of misfolded protein pathology. However, the structure of transmissive mHTT species, and the molecular mechanisms underlying their transmission remain unknown. Using correlative light and electron microscopy (CLEM) and cryo-electron tomography (cryo-ET), we identified two types of aggregation-prone granules in conditioned medium from PC12 cells expressing a mHTT N-terminal fragment: densities enclosed by extracellular vesicles (EVs), and uncoated, amorphous meshworks of heterogeneous oligomers that co-localize with clusters of EVs. In vitro assays confirmed that liposomes induce condensation of polyQ oligomers into higher-order assemblies, resembling the uncoated meshworks observed in PC12 conditioned medium. Our findings provide novel insights into formation and architecture of transmissive mHTT proteins, and highlight the potential role of EVs as both carriers and modulators of transmissive mHTT proteins.
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http://dx.doi.org/10.1016/j.bbrc.2021.04.124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8176346PMC
June 2021

Preliminary Structural Elucidation of β-(1,3)-glucan Synthase from Using Cryo-Electron Tomography.

J Fungi (Basel) 2021 Feb 6;7(2). Epub 2021 Feb 6.

Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA.

Echinocandin drugs have become a front-line therapy against spp. infections due to the increased incidence of infections by species with elevated azole resistance, such as . Echinocandins target the fungal-specific enzyme ß-(1,3)-glucan synthase (GS), which is located in the plasma membrane and catalyzes the biosynthesis of ß-(1,3)-glucan, the major component of the fungal cell wall. However, resistance to echinocandin drugs, which results from hotspot mutations in the catalytic subunits of GS, is an emerging problem. Little structural information on GS is currently available because, thus far, the GS enzyme complex has resisted homogenous purification, limiting our understanding of GS as a major biosynthetic apparatus for cell wall assembly and an important therapeutic drug target. Here, by applying cryo-electron tomography (cryo-ET) and subtomogram analysis, we provide a preliminary structure of the putative GS complex as clusters of hexamers, each subunit with two notable cytosolic domains, the N-terminal and central catalytic domains. This study lays the foundation for structural and functional studies of this elusive protein complex, which will provide insight into fungal cell wall synthesis and the development of more efficacious antifungal therapeutics.
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http://dx.doi.org/10.3390/jof7020120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7914498PMC
February 2021

Evolution of the SARS-CoV-2 proteome in three dimensions (3D) during the first six months of the COVID-19 pandemic.

bioRxiv 2020 Dec 4. Epub 2020 Dec 4.

Three-dimensional structures of SARS-CoV-2 and other coronaviral proteins archived in the Protein Data Bank were used to analyze viral proteome evolution during the first six months of the COVID-19 pandemic. Analyses of spatial locations, chemical properties, and structural and energetic impacts of the observed amino acid changes in >48,000 viral proteome sequences showed how each one of the 29 viral study proteins have undergone amino acid changes. Structural models computed for every unique sequence variant revealed that most substitutions map to protein surfaces and boundary layers with a minority affecting hydrophobic cores. Conservative changes were observed more frequently in cores boundary layers/surfaces. Active sites and protein-protein interfaces showed modest numbers of substitutions. Energetics calculations showed that the impact of substitutions on the thermodynamic stability of the proteome follows a universal bi-Gaussian distribution. Detailed results are presented for six drug discovery targets and four structural proteins comprising the virion, highlighting substitutions with the potential to impact protein structure, enzyme activity, and functional interfaces. Characterizing the evolution of the virus in three dimensions provides testable insights into viral protein function and should aid in structure-based drug discovery efforts as well as the prospective identification of amino acid substitutions with potential for drug resistance.
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http://dx.doi.org/10.1101/2020.12.01.406637DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724657PMC
December 2020

Virtual Boot Camp: COVID-19 evolution and structural biology.

Biochem Mol Biol Educ 2020 09 14;48(5):511-513. Epub 2020 Aug 14.

Research Collaboratory for Structural Bioinformatics Protein Data Bank, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.

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http://dx.doi.org/10.1002/bmb.21428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7590104PMC
September 2020

Structural and functional analyses of photosystem II in the marine diatom .

Proc Natl Acad Sci U S A 2019 08 13;116(35):17316-17322. Epub 2019 Aug 13.

Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ 08854;

A descendant of the red algal lineage, diatoms are unicellular eukaryotic algae characterized by thylakoid membranes that lack the spatial differentiation of stroma and grana stacks found in green algae and higher plants. While the photophysiology of diatoms has been studied extensively, very little is known about the spatial organization of the multimeric photosynthetic protein complexes within their thylakoid membranes. Here, using cryo-electron tomography, proteomics, and biophysical analyses, we elucidate the macromolecular composition, architecture, and spatial distribution of photosystem II complexes in diatom thylakoid membranes. Structural analyses reveal 2 distinct photosystem II populations: loose clusters of complexes associated with antenna proteins and compact 2D crystalline arrays of dimeric cores. Biophysical measurements reveal only 1 photosystem II functional absorption cross section, suggesting that only the former population is photosynthetically active. The tomographic data indicate that the arrays of photosystem II cores are physically separated from those associated with antenna proteins. We hypothesize that the islands of photosystem cores are repair stations, where photodamaged proteins can be replaced. Our results strongly imply convergent evolution between the red and the green photosynthetic lineages toward spatial segregation of dynamic, functional microdomains of photosystem II supercomplexes.
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http://dx.doi.org/10.1073/pnas.1906726116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6717305PMC
August 2019

Demographic Dividends, Human Capital, and Saving.

J Econ Ageing 2016 Apr;7:106-122

Department of Economics, University of Cambridge.

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http://dx.doi.org/10.1016/j.jeoa.2016.02.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918060PMC
April 2016

Plectin-1 as a Biomarker of Malignant Progression in Intraductal Papillary Mucinous Neoplasms: A Multicenter Study.

Pancreas 2016 10;45(9):1353-8

From the *Department of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL; †Department of Pathology and Laboratory Medicine and Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, Los Angeles, CA; Departments of ‡Pathology and Laboratory Medicine, and §Cancer Biology, Mayo Clinic, Jacksonville, FL; ∥Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA; and ¶Department of Bioengineering, School of Engineering and Applied Sciences, and #Robert M. Berne Cardiovasuclar Research Center, School of Medicine, University of Virginia, Charlottesville, VA.

Objective: This study aimed to evaluate Plectin-1 expression as a biomarker of malignant risk for intraductal papillary mucinous neoplasms (IPMNs).

Methods: Plectin-1 immunohistochemistry (IHC) was performed retrospectively on surgical (n = 71) and cytological (n = 33) specimens from Mayo Clinic Jacksonville and UCLA Medical Center, including IPMNs with low-grade dysplasia, high-grade dysplasia (HGD), or an associated invasive adenocarcinoma.

Results: Plectin-1 expression was increased in invasive adenocarcinoma compared with adjacent in situ IPMN (P = 0.005), as well as the in situ HGD component of IPMNs with invasive cancer compared with HGD of IPMNs without invasive cancer (P = 0.02). Plectin IHC discriminated IPMNs with invasive adenocarcinoma from noninvasive IPMN (area under the curve [AUC] of 0.79, 75% sensitivity, and 85% specificity) but was insufficient for discriminating HGD IPMN from low-grade dysplasia IPMNs in surgical resections (AUC of 0.67, 56% sensitivity, and 64% specificity) or fine-needle aspiration specimens (AUC of 0.45).

Conclusions: Although Plectin-1 IHC has insufficient accuracy to be used as a definitive biomarker for malignant risk in the evaluation of IPMN biopsy or cytological specimens, increased Plectin-1 expression observed in both invasive cancer and in situ HGD of malignant IPMNs suggests that it might be successfully leveraged as a cyst fluid biomarker or molecular imaging target.
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http://dx.doi.org/10.1097/MPA.0000000000000652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5021548PMC
October 2016

A combination of high dose rate (10X FFF/2400 MU/min/10 MV X-rays) and total low dose (0.5 Gy) induces a higher rate of apoptosis in melanoma cells in vitro and superior preservation of normal melanocytes.

Melanoma Res 2015 Oct;25(5):376-89

aThe Genomics and Biomarkers Program, University Medical Center bClinical Division, Hackensack University Medical Center, The John Theurer Cancer Center, Hackensack, New Jersey, USA.

The aim of this study was to determine the apoptotic effects, toxicity, and radiosensitization of total low dose irradiation delivered at a high dose rate in vitro to melanoma cells, normal human epidermal melanocytes (HEM), or normal human dermal fibroblasts (HDF) and to study the effect of mitochondrial inhibition in combination with radiation to enhance apoptosis in melanoma cells. Cells irradiated using 10X flattening filter-free (FFF) 10 MV X-rays at a dose rate of 400 or 2400 MU/min and a total dose of 0.25-8 Gy were analyzed by cell/colony counting, MitoTracker, MTT, and DNA-damage assays, as well as by quantitative real-time reverse transcriptase PCR in the presence or absence of mitochondrial respiration inhibitors. A dose rate of 2400 MU/min killed on average five-fold more melanoma cells than a dose rate 400 MU/min at a total dose of 0.5 Gy and preserved 80% survival of HEM and 90% survival of HDF. Increased apoptosis at the 2400 MU/min dose rate is mediated by greater DNA damage, reduced cell proliferation, upregulation of apoptotic genes, and downregulation of cell cycle genes. HEM and HDF were relatively unharmed at 2400 MU/min. Radiation induced upregulation of mitochondrial respiration in both normal and cancer cells, and blocking the respiration with inhibitors enhanced apoptosis only in melanoma cells. A high dose rate with a low total dose (2400 MU/min, 0.5 Gy/10X FFF 10 MV X-rays) enhances radiosensitivity of melanoma cells while reducing radiotoxicity toward HEM and HDF. Selective cytotoxicity of melanoma cells is increased by blocking mitochondrial respiration.
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http://dx.doi.org/10.1097/CMR.0000000000000174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4560269PMC
October 2015

EGF stimulates the activation of EGF receptors and the selective activation of major signaling pathways during mitosis.

Cell Signal 2015 Mar 2;27(3):638-51. Epub 2014 Dec 2.

Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. Electronic address:

Mitosis and epidermal growth factor (EGF) receptor (EGFR) are both targets for cancer therapy. The role of EGFR signaling in mitosis has been rarely studied and poorly understood. The limited studies indicate that the activation of EGFR and downstream signaling pathways is mostly inhibited during mitosis. However, we recently showed that EGFR is phosphorylated in response to EGF stimulation in mitosis. Here we studied EGF-induced EGFR activation and the activation of major signaling pathways downstream of EGFR during mitosis. We showed that EGFR was strongly activated by EGF during mitosis as all the five major tyrosine residues including Y992, Y1045, Y1068, Y1086, and Y1173 were phosphorylated to a level similar to that in the interphase. We further showed that the activated EGFR is able to selectively activate some downstream signaling pathways while avoiding others. Activated EGFR is able to activate PI3K and AKT2, but not AKT1, which may be responsible for the observed effects of EGF against nocodazole-induced cell death. Activated EGFR is also able to activate c-Src, c-Cbl and PLC-γ1 during mitosis. However, activated EGFR is unable to activate ERK1/2 and their downstream substrates RSK and Elk-1. While it activated Ras, EGFR failed to fully activate Raf-1 in mitosis due to the lack of phosphorylation at Y341 and the lack of dephosphorylation at pS259. We conclude that contrary to the dogma, EGFR is activated by EGF during mitosis. Moreover, EGFR-mediated cell signaling is regulated differently from the interphase to specifically serve the needs of the cell in mitosis.
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http://dx.doi.org/10.1016/j.cellsig.2014.11.030DOI Listing
March 2015

Automated in situ hybridization for human papilloma virus.

Appl Immunohistochem Mol Morphol 2014 Sep;22(8):619-22

Department of Pathology and Laboratory Medicine, Emory University Hospital, Atlanta, GA.

With the increased number of requests for high-risk human papilloma virus in situ hybridization (HPV ISH), not only for uterine cervical squamous cell carcinoma (SCC) but also for biopsies and resections of oropharyngeal SCC, and fine needle aspiration cell blocks of metastatic SCC in cervical lymph nodes, we optimized an automated method to replace the manual one we had used. The new technique used the Leica BOND-maX or III immunostainer, already in use for immunohistochemical analysis, with the Enzo HPV type 16/18 and 6/11 probes. We stained 55 surgical biopsies and 41 cell blocks of oropharyngeal SCC. Sensitivity was 90% and 73% for biopsies and cell blocks, respectively, with a specificity of 100% in both. Stain is strong and crisp with no background. Turnaround time is short as runs are performed daily, with up to 30 slides per run. Technologists become trained in a few days, and the repeat rate is low. The only disadvantage is that ISH and IHC cannot be performed simultaneously. We highly recommend this automated technique for high-risk and low-risk HPV ISH and probably with other probes.
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http://dx.doi.org/10.1097/PAI.0b013e3182a501a2DOI Listing
September 2014

Small dense low-density lipoprotein-cholesterol concentrations predict risk for coronary heart disease: the Atherosclerosis Risk In Communities (ARIC) study.

Arterioscler Thromb Vasc Biol 2014 May 20;34(5):1069-77. Epub 2014 Feb 20.

From the Department of Medicine, Baylor College of Medicine and Methodist DeBakey Heart and Vascular Center, Houston, TX (R.C.H., J.W.G., W.S., J.J., S.S.V., C.M.B.); Human Genetics Center, University of Texas Health Science Center School of Public Health, Houston (R.C.D., J.R.C., E.B.); Department of Biostatistics, University of North Carolina at Chapel Hill (D.C.); Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX (S.S.V.); Center for Human Genetic Research and Cardiovascular Research Center, Massachusetts General Hospital, Boston (S.K.); and Department of Medicine, Harvard Medical School, Boston, MA (S.K.).

Objective: To investigate the relationship between plasma levels of small dense low-density lipoprotein-cholesterol (sdLDL-C) and risk for incident coronary heart disease (CHD) in a prospective study among Atherosclerosis Risk in Communities (ARIC) study participants.

Approach And Results: Plasma sdLDL-C was measured in 11 419 men and women of the biracial ARIC study using a newly developed homogeneous assay. A proportional hazards model was used to examine the relationship among sdLDL-C, vascular risk factors, and risk for CHD events (n=1158) for a period of ≈11 years. Plasma sdLDL-C levels were strongly correlated with an atherogenic lipid profile and were higher in patients with diabetes mellitus than non-diabetes mellitus (49.6 versus 42.3 mg/dL; P<0.0001). In a model that included established risk factors, sdLDL-C was associated with incident CHD with a hazard ratio of 1.51 (95% confidence interval, 1.21-1.88) for the highest versus the lowest quartile, respectively. Even in individuals considered to be at low cardiovascular risk based on their LDL-C levels, sdLDL-C predicted risk for incident CHD (hazard ratio, 1.61; 95% confidence interval, 1.04-2.49). Genome-wide association analyses identified genetic variants in 8 loci associated with sdLDL-C levels. These loci were in or close to genes previously associated with risk for CHD. We discovered 1 novel locus, PCSK7, for which genetic variation was significantly associated with sdLDL-C and other lipid factors.

Conclusions: sdLDL-C was associated with incident CHD in ARIC study participants. The novel association of genetic variants in PCSK7 with sdLDL-C and other lipid traits may provide new insights into the role of this gene in lipid metabolism.
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http://dx.doi.org/10.1161/ATVBAHA.114.303284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3999643PMC
May 2014

Differential regulation of transcription factors by location-specific EGF receptor signaling via a spatio-temporal interplay of ERK activation.

PLoS One 2012 12;7(9):e41354. Epub 2012 Sep 12.

The Department of Medical Genetics and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.

It is well established that EGFR signals from both the plasma membrane (PM) and endosome (EN). However, very little is known about whether and how the EGFR signals at the PM and EN to differentially regulate various signaling pathways and the physiological outcomes. In this communication, we established a system that allowed the specific activations of EGFR at different cell locations: PM and EN. PM activation of EGFR is achieved by activation of endocytosis-deficient mutant EGFR1010LL/AA stably expressed in CHO cells (CHO-LL/AA cell). EN activation of EGFR is achieved by activating the wild type EGFR stably expressed in CHO cells (CHO-EGFR cell) after its internalization into EN with a previously reported protocol. We showed that both EGFR activations at PM and EN activated ERK to a similar level, but differentially stimulated transcriptional factors c-jun and c-fos. We further showed that EGFR activations at PM and EN resulted in differential spatio-temporal dynamics of phosphorylated ERK which caused the differential activation of two downstream substrates ELK1 and RSK. Finally we showed that EGFR signaling from PM and EN led to different physiological outcomes. CHO-LL/AA cells that only generate PM EGFR signals have a larger cell size and slower proliferation rate than CHO-EGFR cells. We conclude that location-specific EGFR activation differentially regulates cell functions through a spatio-temporal interplay of ERK activation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041354PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440385PMC
March 2013

Gonadotropin-inhibitory hormone neurons interact directly with gonadotropin-releasing hormone-I and -II neurons in European starling brain.

Endocrinology 2008 Jan 27;149(1):268-78. Epub 2007 Sep 27.

Laboratory of Reproductive Neuroendocrinology, Department of Integrative Biology, University of California at Berkeley, Berkeley, California 94720-3140, USA.

Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic dodecapeptide (SIKPSAYLPLRF-NH(2)) that directly inhibits gonadotropin synthesis and release from quail pituitary. The action of GnIH is mediated by a novel G-protein coupled receptor. This gonadotropin-inhibitory system may be widespread in vertebrates, at least birds and mammals. In these higher vertebrates, histological evidence suggests contact of GnIH immunoreactive axon terminals with GnRH neurons, thus indicating direct regulation of GnRH neuronal activity by GnIH. In this study we investigated the interaction of GnIH and GnRH-I and -II neurons in European starling (Sturnus vulgaris) brain. Cloned starling GnIH precursor cDNA encoded three peptides that possess characteristic LPXRF-amide (X = L or Q) motifs at the C termini. Starling GnIH was further identified as SIKPFANLPLRF-NH(2) by mass spectrometry combined with immunoaffinity purification. GnIH neurons, identified by in situ hybridization and immunocytochemistry (ICC), were clustered in the hypothalamic paraventricular nucleus. GnIH immunoreactive fiber terminals were present in the external layer of the median eminence in addition to the preoptic area and midbrain, where GnRH-I and GnRH-II neuronal cell bodies exist, respectively. GnIH axon terminals on GnRH-I and -II neurons were shown by GnIH and GnRH double-label ICC. Furthermore, the expression of starling GnIH receptor mRNA was identified in both GnRH-I and GnRH-II neurons by in situ hybridization combined with GnRH ICC. The cellular localization of GnIH receptor has not previously been identified in any vertebrate brain. Thus, GnIH may regulate reproduction of vertebrates by directly modulating GnRH-I and GnRH-II neuronal activity, in addition to influencing the pituitary gland.
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http://dx.doi.org/10.1210/en.2007-0983DOI Listing
January 2008
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