Medical Cell Biology Commons^™

Functional Interpretation Of Atad3a Variants In Neuro-Mitochondrial Phenotypes, Zheng Yie Yap, Yo Han Park, Saskia B Wortmann, Adam C Gunning, Shlomit Ezer, Sukyeong Lee, Lita Duraine, Ekkehard Wilichowski, Kate Wilson, Johannes A Mayr, Matias Wagner, Hong Li, Usha Kini, Emily Davis Black, Kristin G Monaghan, James R Lupski, Sian Ellard, Dominik S Westphal, Tamar Harel, Wan Hee Yoon

Faculty, Staff and Students Publications

BACKGROUND: ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane-anchored protein involved in diverse processes including mitochondrial dynamics, mitochondrial DNA organization, and cholesterol metabolism. Biallelic deletions (null), recessive missense variants (hypomorph), and heterozygous missense variants or duplications (antimorph) in ATAD3A lead to neurological syndromes in humans.

METHODS: To expand the mutational spectrum of ATAD3A variants and to provide functional interpretation of missense alleles in trans to deletion alleles, we performed exome sequencing for identification of single nucleotide variants (SNVs) and copy number variants (CNVs) in ATAD3A in individuals with neurological and mitochondrial phenotypes. A Drosophila Atad3a Gal4 …

Obstructive Sleep Apnea And Dementia-Common Gene Associations Through Network-Based Identification Of Common Driver Genes, Hyun-Hwan Jeong, Arvind Chandrakantan, Adam C Adler

Faculty, Staff and Students Publications

BACKGROUND: Obstructive Sleep Apnea (OSA) occurs in 7% of the adult population. The relationship between neurodegenerative diseases such as dementia and sleep disorders have long attracted clinical attention; however, no comprehensive data exists elucidating common gene expression between the two diseases. The objective of this study was to (1) demonstrate the practicability and feasibility of utilizing a systems biology approach called network-based identification of common driver genes (NICD) to identify common genomic features between two associated diseases and (2) utilize this approach to identify genes associated with both OSA and dementia.

METHODS: This study utilized 2 public databases (PCNet, DisGeNET) …

Glucagon Blockade Restores Functional Β-Cell Mass In Type 1 Diabetic Mice And Enhances Function Of Human Islets, May-Yun Wang, E Danielle Dean, Ezekiel Quittner-Strom, Yi Zhu, Kamrul H Chowdhury, Zhuzhen Zhang, Shangang Zhao, Na Li, Reshing Ye, Young Lee, Yiyi Zhang, Shiuhwei Chen, Xinxin Yu, Derek C Leonard, Greg Poffenberger, Alison Von Deylen, S Kay Mccorkle, Amnon Schlegel, Kyle W Sloop, Alexander M Efanov, Ruth E Gimeno, Philipp E Scherer, Alvin C Powers, Roger H Unger, William L Holland

Faculty, Staff and Students Publications

We evaluated the potential for a monoclonal antibody antagonist of the glucagon receptor (Ab-4) to maintain glucose homeostasis in type 1 diabetic rodents. We noted durable and sustained improvements in glycemia which persist long after treatment withdrawal. Ab-4 promoted β-cell survival and enhanced the recovery of insulin+ islet mass with concomitant increases in circulating insulin and C peptide. In PANIC-ATTAC mice, an inducible model of β-cell apoptosis which allows for robust assessment of β-cell regeneration following caspase-8–induced diabetes, Ab-4 drove a 6.7-fold increase in β-cell mass. Lineage tracing suggests that this restoration of functional insulin-producing cells was at least partially …

Discovery And Characterization Of Bromodomain 2-Specific Inhibitors Of Brdt, Zhifeng Yu, Angela F Ku, Justin L Anglin, Rajesh Sharma, Melek Nihan Ucisik, John C Faver, Feng Li, Pranavanand Nyshadham, Nicholas Simmons, Kiran L Sharma, Sureshbabu Nagarajan, Kevin Riehle, Gundeep Kaur, Banumathi Sankaran, Marta Storl-Desmond, Stephen S Palmer, Damian W Young, Choel Kim, Martin M Matzuk

Faculty, Staff and Students Publications

Bromodomain testis (BRDT), a member of the bromodomain and extraterminal (BET) subfamily that includes the cancer targets BRD2, BRD3, and BRD4, is a validated contraceptive target. All BET subfamily members have two tandem bromodomains (BD1 and BD2). Knockout mice lacking BRDT-BD1 or both bromodomains are infertile. Treatment of mice with JQ1, a BET BD1/BD2 nonselective inhibitor with the highest affinity for BRD4, disrupts spermatogenesis and reduces sperm number and motility. To assess the contribution of each BRDT bromodomain, we screened our collection of DNA-encoded chemical libraries for BRDT-BD1 and BRDT-BD2 binders. High-enrichment hits were identified and resynthesized off-DNA and examined …

Fusobacteriumnucleatum Adheres To Clostridioides Difficile Via The Radd Adhesin To Enhance Biofilm Formation In Intestinal Mucus, Melinda A Engevik, Heather A Danhof, Jennifer Auchtung, Bradley T Endres, Wenly Ruan, Eugénie Bassères, Amy C Engevik, Qinglong Wu, Maribeth Nicholson, Ruth Ann Luna, Kevin W Garey, Sue E Crawford, Mary K Estes, Renate Lux, Mary Beth Yacyshyn, Bruce Yacyshyn, Tor Savidge, Robert A Britton, James Versalovic

Faculty, Staff and Students Publications

Background:

Although Clostridioides difficile infection (CDI) is known to involve the disruption of the gut microbiota, little is understood regarding how mucus-associated microbes interact with C. difficile. We hypothesized that select mucus-associated bacteria would promote C. difficile colonization and biofilm formation.

Methods/Results:

To create a model of the human intestinal mucus layer and gut microbiota, we used bioreactors inoculated with healthy human feces, treated with clindamycin and infected with C. difficile with the addition of human MUC2-coated coverslips. C. difficile was found to colonize and form biofilms on MUC2-coated coverslips and 16S rRNA sequencing revealed a unique biofilm profile …

The Mitochondrial Protease Lonp1 Promotes Proteasome Inhibitor Resistance In Multiple Myeloma, Laure Maneix, Melanie A Sweeney, Sukyeong Lee, Polina Iakova, Shannon E Moree, Ergun Sahin, Premal Lulla, Sarvari V Yellapragada, Francis T F Tsai, Andre Catic

Faculty, Staff and Students Publications

Multiple myeloma and its precursor plasma cell dyscrasias affect 3% of the elderly population in the US. Proteasome inhibitors are an essential part of several standard drug combinations used to treat this incurable cancer. These drugs interfere with the main pathway of protein degradation and lead to the accumulation of damaged proteins inside cells. Despite promising initial responses, multiple myeloma cells eventually become drug resistant in most patients. The biology behind relapsed/refractory multiple myeloma is complex and poorly understood. Several studies provide evidence that in addition to the proteasome, mitochondrial proteases can also contribute to protein quality control outside of …

Calcium Ions Trigger The Exposure Of Phosphatidylserine On The Surface Of Necrotic Cells, Yoshitaka Furuta, Omar Pena-Ramos, Zao Li, Lucia Chiao, Zheng Zhou

Faculty, Staff and Students Publications

Intracellular Ca2+ level is under strict regulation through calcium channels and storage pools including the endoplasmic reticulum (ER). Mutations in certain ion channel subunits, which cause mis-regulated Ca2+ influx, induce the excitotoxic necrosis of neurons. In the nematode Caenorhabditis elegans, dominant mutations in the DEG/ENaC sodium channel subunit MEC-4 induce six mechanosensory (touch) neurons to undergo excitotoxic necrosis. These necrotic neurons are subsequently engulfed and digested by neighboring hypodermal cells. We previously reported that necrotic touch neurons actively expose phosphatidylserine (PS), an "eat-me" signal, to attract engulfing cells. However, the upstream signal that triggers PS externalization remained elusive. Here we …

Protein-Functionalized Poly(Ethylene Glycol) Hydrogels As Scaffolds For Monolayer Organoid Culture, Reid L Wilson, Ganesh Swaminathan, Khalil Ettayebi, Carolyn Bomidi, Xi-Lei Zeng, Sarah E Blutt, Mary K Estes, K Jane Grande-Allen

Faculty, Staff and Students Publications

Stem cell-derived, organotypic in vitro models, known as organoids, have emerged as superior alternatives to traditional cell culture models due to their unparalleled ability to recreate complex physiological and pathophysiological processes. For this reason, they are attractive targets of tissue-engineering efforts, as constructs that include organoid technology would be expected to better simulate the many functions of the desired tissue or organ. While the 3D spheroidal architecture that is the default architecture of most organoid models may be preferred for some applications, 2D monolayer arrangements remain the preferred organization for many applications in tissue engineering. Therefore, in this work, we …

Enhancing Glucose Metabolism Via Gluconeogenesis Is Therapeutic In A Zebrafish Model Of Dravet Syndrome, Rajeswari Banerji, Christopher Huynh, Francisco Figueroa, Matthew T Dinday, Scott C Baraban, Manisha Patel

Faculty, Staff and Students Publications

Energy-producing pathways are novel therapeutic targets for the treatment of neurodevelopmental disorders. Here, we focussed on correcting metabolic defects in a catastrophic paediatric epilepsy, Dravet syndrome which is caused by mutations in sodium channel NaV1.1 gene, SCN1A. We utilized a translatable zebrafish model of Dravet syndrome (scn1lab) which exhibits key characteristics of patients with Dravet syndrome and shows metabolic deficits accompanied by down-regulation of gluconeogenesis genes, pck1 and pck2. Using a metabolism-based small library screen, we identified compounds that increased gluconeogenesis via up-regulation of pck1 gene expression in scn1lab larvae. Treatment with PK11195, a pck1 activator …

The E3 Ligase Traf4 Promotes Igf Signaling By Mediating Atypical Ubiquitination Of Irs-1, Wenjuan Yu, Ramesh Singh, Zhao Wang, Bert W O'Malley, Ping Yi

Faculty, Staff and Students Publications

Insulin-like growth factor (IGF) is a potent mitogen that activates the IGF receptor (IGFR)/insulin receptor substrate (IRS) axis, thus stimulating growth in normal cells and uncontrolled cell proliferation in cancer. Posttranslational modifications of IRS such as ubiquitination tightly control IGF signaling, and we previously identified IRS-1 as a potential substrate for the E3 ubiquitin ligase TRAF4 using an unbiased screen. Here we provide evidence that TRAF4-mediated ubiquitination of IRS-1 is physiologically relevant and crucial for IGF signal transduction. Through site-directed mutagenesis we found that TRAF4 promotes an atypical K29-linked ubiquitination at the C-terminal end of IRS-1. Its depletion abolishes AKT …

Genomic Mapping Of Dna-Repair Reaction Intermediates In Living Cells With Engineered Dna Structure-Trap Proteins, Jingjing Liu, Qian Mei, Sadeieh Nimer, Devon M Fitzgerald, Susan M Rosenberg

Faculty, Staff and Students Publications

Diverse DNA structures occur as reaction intermediates in various DNA-damage and -repair mechanisms, most of which results from replication stress. We harness the power of proteins evolutionarily optimized to bind and "trap" specific DNA reaction-intermediate structures, to quantify the structures, and discern the mechanisms of their occurrence in cells. The engineered proteins also allow genomic mapping of sites at which specific DNA structures occur preferentially, using a structure-trapping protein and ChIP-seq- or Cut-and-Tag-like methods. Genome-wide identification of sites with recurrent DNA-damage intermediates has illuminated mechanisms implicated in genome instability, replication stress, and chromosome fragility. Here, we describe X-seq, for identifying …

Loss Of Class Iii Phosphoinositide 3-Kinase Vps34 Results In Cone Degeneration, Ammaji Rajala, Feng He, Robert E Anderson, Theodore G Wensel, Raju V S Rajala

Faculty, Staff and Students Publications

The major pathway for the production of the low-abundance membrane lipid phosphatidylinositol 3-phosphate (PI(3)P) synthesis is catalyzed by class III phosphoinositide 3-kinase (PI3K) Vps34. The absence of Vps34 was previously found to disrupt autophagy and other membrane-trafficking pathways in some sensory neurons, but the roles of phosphatidylinositol 3-phosphate and Vps34 in cone photoreceptor cells have not previously been explored. We found that the deletion of Vps34 in neighboring rods in mouse retina did not disrupt cone function up to 8 weeks after birth, despite diminished rod function. Immunoblotting and lipid analysis of cones isolated from the cone-dominant retinas of the …

Mir-30a Targets Gene Networks That Promote Browning Of Human And Mouse Adipocytes, Pradip K Saha, Mark P Hamilton, Kimal Rajapakshe, Vasanta Putluri, Jessica B Felix, Peter Masschelin, Aaron R Cox, Mandeep Bajaj, Nagireddy Putluri, Cristian Coarfa, Sean M Hartig

Faculty, Staff and Students Publications

MicroRNA-30a (miR-30a) impacts adipocyte function, and its expression in white adipose tissue (WAT) correlates with insulin sensitivity in obesity. Bioinformatic analysis demonstrates that miR-30a expression contributes to 2% of all miRNA expression in human tissues. However, molecular mechanisms of miR-30a function in fat cells remain unclear. Here, we expanded our understanding of how miR-30a expression contributes to antidiabetic peroxisome proliferator-activated receptor-γ (PPARγ) agonist activity and metabolic functions in adipocytes. We found that WAT isolated from diabetic patients shows reduced miR-30a levels and diminished expression of the canonical PPARγ target genes ADIPOQ and FABP4 relative to lean counterparts. In human adipocytes, …

Structural Insights Of Transcriptionally Active, Full-Length Androgen Receptor Coactivator Complexes, Xinzhe Yu, Ping Yi, Ross A Hamilton, Hong Shen, Muyuan Chen, Charles E Foulds, Michael A Mancini, Steven J Ludtke, Zhao Wang, Bert W O'Malley

Faculty, Staff and Students Publications

Steroid receptors activate gene transcription by recruiting coactivators to initiate transcription of their target genes. For most nuclear receptors, the ligand-dependent activation function domain-2 (AF-2) is a primary contributor to the nuclear receptor (NR) transcriptional activity. In contrast to other steroid receptors, such as ERα, the activation function of androgen receptor (AR) is largely dependent on its ligand-independent AF-1 located in its N-terminal domain (NTD). It remains unclear why AR utilizes a different AF domain from other receptors despite that NRs share similar domain organizations. Here, we present cryoelectron microscopy (cryo-EM) structures of DNA-bound full-length AR and its complex structure …

Targeting Pd-L1 In Non-Small Cell Lung Cancer Using Car T Cells, Ming Liu, Xu Wang, Wei Li, Xinfang Yu, Pedro Flores-Villanueva, Zijun Y Xu-Monette, Ling Li, Mingzhi Zhang, Ken H Young, Xiaodong Ma, Yong Li

Faculty, Staff and Students Publications

Antibodies against programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have dramatically changed the landscape of therapies for non-small cell lung carcinoma (NSCLC); however, the majority of patients do not respond to these agents. In addition, hyperprogressive disease (HPD) develops in a larger portion of NSCLC patients treated with PD-1/PD-L1 inhibitors than in patients treated with standard chemotherapy. The use of chimeric antigen receptor (CAR) T cells has been successful to treat blood cancers but not for solid tumors like NSCLC. In this work, we constructed CAR T cells that target PD-L1 and evaluated their efficacy in NSCLC …

The Impact Of Diabetic Foot Ulcers And Unilateral Offloading Footwear On Gait In People With Diabetes, Erica Ling, Brian Lepow, He Zhou, Ana Enriquez, Ashley Mullen, Bijan Najafi

Faculty, Staff and Students Publications

BACKGROUND: Unilateral offloading footwear prescribed to patients with diabetic foot ulcers elevates one limb relative to the other, which may lead to limp and abnormal gait. This study investigated whether the unilateral foot ulcer and offloading combination negatively impacts gait function beyond diabetic peripheral neuropathy.

METHODS: Eighty-six participants were recruited in 3 groups: 12 with diabetic peripheral neuropathy and unilateral foot ulcers wearing offloading footwear (offloading group, age = 55.6 ± 9.5 years, BMI = 30.9 ± 4.5 kg/m

FINDINGS: The offloading group exhibited deteriorated gait function compared to the non-diabetic group (p < 0.005, Cohen's effect size d = 0.90-2.61). They also had decreased gait speed (p < 0.001, d = 1.79) and stride length (p < 0.001, d = 1.76), as well as increased gait cycle time (p < 0.001, d = 1.67) and limp (p < 0.050, d = 0.72-1.49) compared to the neuropathy group. The offloading group showed increased gait unsteadiness compared to the neuropathy group, but the difference did not reach statistical significance in our samples.

INTERPRETATION: This study demonstrated that while diabetic …

Perioperative Acute Kidney Injury, Sam D Gumbert, Felix Kork, Maisie L Jackson, Naveen Vanga, Semhar J Ghebremichael, Christy Y Wang, Holger K Eltzschig

Faculty, Staff and Students Publications

Perioperative organ injury is among the leading causes of morbidity and mortality of surgical patients. Among different types of perioperative organ injury, acute kidney injury occurs particularly frequently and has an exceptionally detrimental effect on surgical outcomes. Currently, acute kidney injury is most commonly diagnosed by assessing increases in serum creatinine concentration or decreased urine output. Recently, novel biomarkers have become a focus of translational research for improving timely detection and prognosis for acute kidney injury. However, specificity and timing of biomarker release continue to present challenges to their integration into existing diagnostic regimens. Despite many clinical trials using various …

Residues And Residue Pairs Of Evolutionary Importance Differentially Direct Signaling Bias Of D2 Dopamine Receptors, María E Terrón-Díaz, Sara J Wright, Melina A Agosto, Olivier Lichtarge, Theodore G Wensel

Faculty, Staff and Students Publications

The D2 dopamine receptor and the serotonin 5-hydroxytryptamine 2A receptor (5-HT2A) are closely-related G-protein–coupled receptors (GPCRs) from the class A bioamine subfamily. Despite structural similarity, they respond to distinct ligands through distinct downstream pathways, whose dysregulation is linked to depression, bipolar disorder, addiction, and psychosis. They are important drug targets, and it is important to understand how their bias toward G-protein versus β-arrestin signaling pathways is regulated. Previously, evolution-based computational approaches, difference Evolutionary Trace and Evolutionary Trace–Mutual information (ET-Mip), revealed residues and residue pairs that, when switched in the D2 receptor to the corresponding residues from 5-HT2A, altered ligand potency …

Examining Multiple Cellular Pathways At Once Using Multiplex Hextuple Luciferase Assaying, Alejandro Sarrion-Perdigones, Lyra Chang, Yezabel Gonzalez, Tatiana Gallego-Flores, Damian W Young, Koen J T Venken

Faculty, Staff and Students Publications

Sensitive simultaneous assessment of multiple signaling pathways within the same cells requires orthogonal reporters that can assay over large dynamic ranges. Luciferases are such genetically encoded candidates due to their sensitivity, versatility, and cost-effectiveness. We expand luciferase multiplexing in post-lysis endpoint luciferase assays from two to six. Light emissions are distinguished by a combination of distinct substrates and emission spectra deconvolution. All six luciferase reporter units are stitched together into one plasmid facilitating delivery of all reporter units through a process we termed solotransfection, minimizing experimental errors. We engineer a multiplex hextuple luciferase assay to probe pathway fluxes through five …