Medical Biochemistry Commons^™

Regulating Phase Transition In Neurodegenerative Diseases By Nuclear Import Receptors, Amandeep Girdhar, Lin Guo

Department of Biochemistry and Molecular Biology Faculty Papers

RNA-binding proteins (RBPs) with a low-complexity prion-like domain (PLD) can undergo aberrant phase transitions and have been implicated in neurodegenerative diseases such as ALS and FTD. Several nuclear RBPs mislocalize to cytoplasmic inclusions in disease conditions. Impairment in nucleocytoplasmic transport is another major event observed in ageing and in neurodegenerative disorders. Nuclear import receptors (NIRs) regulate the nucleocytoplasmic transport of different RBPs bearing a nuclear localization signal by restoring their nuclear localization. NIRs can also specifically dissolve or prevent the aggregation and liquid–liquid phase separation of wild-type or disease-linked mutant RBPs, due to their chaperoning activity. This review focuses on …

Kalium Channelrhodopsins Are Natural Light-Gated Potassium Channels That Mediate Optogenetic Inhibition, Elena G Govorunova, Yueyang Gou, Oleg A Sineshchekov, Hai Li, Xiaoyu Lu, Yumei Wang, Leonid S Brown, François St-Pierre, Mingshan Xue, John L Spudich

Faculty, Staff and Student Publications

Channelrhodopsins are used widely for optical control of neurons, in which they generate photoinduced proton, sodium or chloride influx. Potassium (K+) is central to neuron electrophysiology, yet no natural K+-selective light-gated channel has been identified. Here, we report kalium channelrhodopsins (KCRs) from Hyphochytrium catenoides. Previously known gated potassium channels are mainly ligand- or voltage-gated and share a conserved K+-selectivity filter. KCRs differ in that they are light-gated and have independently evolved an alternative K+ selectivity mechanism. The KCRs are potent, highly selective of K+ over Na+, and open in less than 1 ms following photoactivation. The permeability ratio PK/PNa of …

An Rtn4/Nogo-A-Interacting Micropeptide Modulates Synaptic Plasticity With Age, S. Kragness, Z. Clark, A. Mullin, J. Guidry, L. R. Earls

School of Medicine Faculty Publications

Micropeptides, encoded from small open reading frames of 300 nucleotides or less, are hidden throughout mammalian genomes, though few functional studies of micropeptides in the brain are published. Here, we describe a micropeptide known as the Plasticity–Associated Neural Transcript Short (Pants), located in the 22q11.2 region of the human genome, the microdeletion of which conveys a high risk for schizophrenia. Our data show that Pants is upregulated in early adulthood in the mossy fiber circuit of the hippocampus, where it exerts a powerful negative effect on long-term potentiation (LTP). Further, we find that Pants is secreted from neurons, where it …

Recognition Of The Tdp-43 Nuclear Localization Signal By Importin Α1/Β, Steven G Doll, Hamed Meshkin, Alexander J Bryer, Fenglin Li, Ying-Hui Ko, Ravi K Lokareddy, Richard E Gillilan, Kushol Gupta, Juan R Perilla, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Cytoplasmic mislocalization of the TAR-DNA binding protein of 43 kDa (TDP-43) leads to large, insoluble aggregates that are a hallmark of amyotrophic lateral sclerosis and frontotemporal dementia. Here, we study how importin α1/β recognizes TDP-43 bipartite nuclear localization signal (NLS). We find that the NLS makes extensive contacts with importin α1, especially at the minor NLS-binding site. NLS binding results in steric clashes with the C terminus of importin α1 that disrupts the TDP-43 N-terminal domain (NTD) dimerization interface. A putative phosphorylation site in the proximity of TDP-43 R83 at the minor NLS site destabilizes binding to importins by reducing …

Crispr/Cas13 Effectors Have Differing Extents Of Off-Target Effects That Limit Their Utility In Eukaryotic Cells, Yuxi Ai, Dongming Liang, Jeremy E Wilusz

Faculty, Staff and Students Publications

CRISPR/Cas13 effectors have garnered increasing attention as easily customizable tools for detecting and depleting RNAs of interest. Near perfect complementarity between a target RNA and the Cas13-associated guide RNA is required for activation of Cas13 ribonuclease activity. Nonetheless, the specificity of Cas13 effectors in eukaryotic cells has been debated as the Cas13 nuclease domains can be exposed on the enzyme surface, providing the potential for promiscuous cleavage of nearby RNAs (so-called collateral damage). Here, using co-transfection assays in Drosophila and human cells, we found that the off-target effects of RxCas13d, a commonly used Cas13 effector, can be as strong as …

Phosphatidylserine And Phosphatidylethanolamine Asymmetry Have A Negligible Effect On The Global Structure, Dynamics, And Interactions Of The Kras Lipid Anchor, Mussie K Araya, Alemayehu A Gorfe

Faculty, Staff and Student Publications

The intrinsically disordered C-terminus of the prominent oncogenic protein KRAS-4B (KRAS) selectively interacts and clusters with phosphatidylserine (PS) lipids in the plasma membrane (PM). This 11-residue segment, called tK, contains a polybasic domain (PBD) of six contiguous lysine residues and a farnesylated cysteine. Previous molecular dynamics (MD) simulation studies of tK in phosphatidylcholine (PC)/PS bilayers have suggested that backbone conformational dynamics modulate tK-PS interactions. These simulations have been conducted in symmetric membranes whereas the PM is compositionally asymmetric, with the inner leaflet, where KRAS is localized, being enriched with PS and phosphatidylethanolamine (PE) lipids. To examine if bilayer asymmetry affects …

Channelopathy Of Small- And Intermediate-Conductance Ca2+-Activated K+ Channels, Young-Woo Nam, Miles Downey, Mohammad Asikur Rahman, Meng Cui, Miao Zhang

Pharmacy Faculty Articles and Research

Small- and intermediate-conductance Ca²⁺-activated K⁺ (K_Ca2.x/K_Ca3.1 also called SK/IK) channels are gated exclusively by intracellular Ca²⁺. The Ca²⁺ binding protein calmodulin confers sub-micromolar Ca²⁺ sensitivity to the channel-calmodulin complex. The calmodulin C-lobe is constitutively associated with the proximal C-terminus of the channel. Interactions between calmodulin N-lobe and the channel S4-S5 linker are Ca²⁺-dependent, which subsequently trigger conformational changes in the channel pore and open the gate. KCNN genes encode four subtypes, including KCNN1 for K_Ca2.1 (SK1), KCNN2 for K_Ca2.2 (SK2), KCNN3 for K …

Evaluation Of Long-Chain Fatty Acid Respiration In Neonatal Mouse Cardiomyocytes Using Seahorse Instrument, Aude Angelini, Xinchun Pi, Liang Xie

Faculty, Staff and Students Publications

Metabolic switches play a critical role in the pathophysiology of cardiac diseases, including heart failure. Here, we describe an assay for long-chain fatty acid oxidation in neonatal mouse cardiomyocytes by using a SeaHorse Flux Analyzer (Agilent). This protocol is a simplified but robust adaptation of the standard protocol that enables metabolic measurements in cells isolated from transgenic mouse models, which can be timesaving and informative. Cell isolation and culture represent a critical point that may require bench optimization.

For complete details on the use and execution of this protocol, please refer to Angelini et al. (2021).

Genomic Features Underlie The Co-Option Of Sva Transposons As Cis-Regulatory Elements In Human Pluripotent Stem Cells, Samantha M Barnada, Andrew Isopi, Daniela Tejada-Martinez, Clément Goubert, Sruti Patoori, Luca Pagliaroli, Mason Tracewell, Marco Trizzino

Department of Biochemistry and Molecular Biology Faculty Papers

Domestication of transposable elements (TEs) into functional cis-regulatory elements is a widespread phenomenon. However, the mechanisms behind why some TEs are co-opted as functional enhancers while others are not are underappreciated. SINE-VNTR-Alus (SVAs) are the youngest group of transposons in the human genome, where ~3,700 copies are annotated, nearly half of which are human-specific. Many studies indicate that SVAs are among the most frequently co-opted TEs in human gene regulation, but the mechanisms underlying such processes have not yet been thoroughly investigated. Here, we leveraged CRISPR-interference (CRISPRi), computational and functional genomics to elucidate the genomic features that underlie SVA domestication …

Lysosomal Zn 2+ Release Triggers Rapid, Mitochondria-Mediated, Non-Apoptotic Cell Death In Metastatic Melanoma, Wanlu Du, Mingxue Gu, Meiqin Hu, Timothy Nold, Prateeksunder Pinchi, Wei Chen, Michael Ryan, Ahmed Bannaga, Haoxing Xu

Medical Student Research Symposium

During tumor progression, lysosome function is often maladaptively upregulated to match the high energy demand required for cancer cell hyper-proliferation and invasion. Here, we report that mucolipin TRP channel 1 (TRPML1), a lysosomal Ca2+ and Zn2+ release channel that regulates multiple aspects of lysosome function, is dramatically upregulated in metastatic melanoma cells compared with normal cells. TRPML-specific synthetic agonists (ML-SAs) are sufficient to induce rapid (within hours) lysosomal Zn2+-dependent necrotic cell death in metastatic melanoma cells while completely sparing normal cells. ML-SA-caused mitochondria swelling and dysfunction lead to cellular ATP depletion. While pharmacological inhibition or genetic silencing of TRPML1 in …

Intrabody-Mediated Postsynaptic Recruitment Of Camkiiα Improves Memory, Anthony Chifor, Jeongyoon Choi Dr., Joongkyu Park Dr.

Medical Student Research Symposium

Long-term potentiation (LTP), the selective strengthening of specific synapses based on recent activity, has widely been accepted as the biological mechanism responsible for learning and memory. N-methyl-D-aspartate receptors (NMDARs) play a critical role in LTP, which when activated, result in a surge of postsynaptic intracellular calcium levels. The calcium rise during LTP results in the activation of Ca²⁺/calmodulin-dependent kinase II alpha (CaMKIIa), which consequently enacts multiple cellular effects that ultimately result in the strengthening of synaptic connections. Previous work has examined the effects of CaMKIIa overexpression in rat hippocampi on spatial memory, however, significant but limited improvement in …

Antigen Staining For Detection Of Muc13 And Muc16 Expression In Carcinoma Tissue, Jose A. Benitez

MEDI 9331 Scholarly Activities Clinical Years

MUC13 and MUC16 are epithelial expressed proteins implicated in various carcinomas. Overexpression of these biomarkers appear to play a role in tumor growth; this discovery has paved a road for multiple studies discussing the potential of targeting mucin proteins and optimize immunotherapy approaches against carcinomas. Our study serves to investigate the level of expression of MUC13 and MUC16 in cancerous and normal tissue and to discuss the implications our findings may have for the utilization of these biomarkers for cancer therapy.

Biophysical Insight Into The Sars-Cov2 Spike–Ace2 Interaction And Its Modulation By Hepcidin Through A Multifaceted Computational Approach, Hamid Hadi-Alijanvand, Luisa Di Paola, Guang Hu, David M. Leitner, Gennady M. Verkhivker, Peixin Sun, Humanath Poudel, Alessandro Giuliani

Mathematics, Physics, and Computer Science Faculty Articles and Research

At the center of the SARS-CoV2 infection, the spike protein and its interaction with the human receptor ACE2 play a central role in the molecular machinery of SARS-CoV2 infection of human cells. Vaccine therapies are a valuable barrier to the worst effects of the virus and to its diffusion, but the need of purposed drugs is emerging as a core target of the fight against COVID19. In this respect, the repurposing of drugs has already led to discovery of drugs thought to reduce the effects of the cytokine storm, but still a drug targeting the spike protein, in the infection …

Alternate Site Pacing And The Impact On Intracellular Calcium Handling During The Post-Extrasystolic Cardiac Cycle, Kent Ozcan, Lawrence Mulligan

Rowan-Virtua Research Day

Objective: Previous work has shown that alternate site (RV apex) results in myocardial dysfunction. With the development of tools to place endocardial pacing leads in locations that create physiological pacing activation, we sought to evaluate how ventricular trans-septal or left ventricular apical placement pacing differs from right atrial pacing. We will evaluate how these chronic pacing modes impact the PR and RF at baseline, 0, and 16 weeks in the canine heart.

Methods: Quantitative analysis will be performed on previously generated data. The data set includes pacing of 15 dogs total (8 with trans-septal leads & 7 with left ventricular …

Applying Mci-062, A Novel Pan-Ras Inhibitor, To Treat Kras-Mutant Lung Cancer, Richard Fu

Honors Theses

RAS is a prevalent oncogene that is mutated in 27% of human cancers. Gain-of-function RAS mutations activate multiple downstream pathways, including the RAS-RAF-MEK-ERK and PI3K/AKT/mTOR pathways, which are critical in tumorigenesis and cancer cell proliferation. RAS proteins such as KRAS, a member of the RAS protein family, and their downstream effectors are attractive targets for cancer therapy since their mutations act as frequent drivers in lung, colorectal, and pancreatic cancers. However, RAS proteins have relatively smooth surfaces that lack traditional binding pockets, making inhibitors specific to RAS difficult to create. Recently, a novel small molecule pan-RAS inhibitor named MCI-062 was …

Applying Mci-062, A Novel Pan-Ras Inhibitor, To Treat Kras-Mutant Lung Cancer., Richard Fu

Poster Presentations

Honors thesis poster presentation.

RAS, one of the most prevalent oncogenes, is mutated in 27% of human cancers. Gainof- function RAS mutations activate multiple downstream pathways, including the RASRAF- MEK-ERK and PI3K/AKT/mTOR pathways, which are critical in tumorigenesis and cancer cell proliferation. The RAS proteins KRAS, HRAS, and NRAS along with their downstream effectors are attractive targets for cancer therapy since they act as frequent drivers in lung, colorectal, and pancreatic cancers. However, RAS proteins have relatively smooth surfaces that lack traditional binding pockets, making inhibitors specific to RAS difficult to create. Recently, a novel small molecule pan-RAS inhibitor named …

Knockdown Of C. Elegans Nad Kinases Nadk-1 Or Nadk-2 Induces An Antioxidant Response Without Affecting Lifespan, Henry Gong

Electronic Theses and Dissertations

Nearly all multicellular organisms show changes in redox balance with aging leading to oxidative damage of macromolecules. This study investigated the role of the [NADP⁺]/[NADPH] redox couple in aging. This redox couple plays an important role in maintaining tissue redox balance and becomes slightly more oxidized in aged tissues. NADPH is a major source of reducing equivalents for enzymes that detoxify hydrogen peroxide. However, catalase detoxifies hydrogen peroxide independently of NADPH. But catalase is absent from mitochondria, a major source of hydrogen peroxide, where instead glutathione plays the major role in hydrogen peroxide detoxification in an NADPH-dependent manner. …

Mechanism Of Rare Variant In Acta2, P.Arg149cys, Driving Diverse Vascular Disease, Kaveeta Kaw

Dissertations and Theses (Open Access)

Heterozygous variants in ACTA2 (smooth muscle (SM) α-actin) predispose to thoracic aortic aneurysms and dissections (TAAD) and early-onset coronary artery disease (CAD). The most common ACTA2 mutation is a genetic alteration of arginine 149 to a cysteine, ACTA2 p.Arg149Cys, which accounts for disease in 24% of all ACTA2 mutation carriers.(1) ACTA2 p.Arg149Cys mutation carriers present with either TAAD or CAD but rarely have both diseases. To identify the molecular mechanisms dictating whether an individual with ACTA2 p.Arg149Cys develops TAAD or CAD, CRISPR/Cas9 technology was used to generate the mutant mouse, Acta2^R149C/+, in a C57BL6 background. Acta2^R149C/+ mice …

Heterozygous Frameshift Variants In Hnrnpa2b1 Cause Early-Onset Oculopharyngeal Muscular Dystrophy, Hong Joo Kim, Payam Mohassel, Sandra Donkervoort, Lin Guo, Kevin O'Donovan, Maura Coughlin, Xaviere Lornage, Nicola Foulds, Simon R Hammans, A Reghan Foley, Charlotte M Fare, Alice F Ford, Masashi Ogasawara, Aki Sato, Aritoshi Iida, Pinki Munot, Gautam Ambegaonkar, Rahul Phadke, Dominic G O'Donovan, Rebecca Buchert, Mona Grimmel, Ana Töpf, Irina T Zaharieva, Lauren Brady, Ying Hu, Thomas E Lloyd, Andrea Klein, Maja Steinlin, Alice Kuster, Sandra Mercier, Pascale Marcorelles, Yann Péréon, Emmanuelle Fleurence, Adnan Manzur, Sarah Ennis, Rosanna Upstill-Goddard, Luca Bello, Cinzia Bertolin, Elena Pegoraro, Leonardo Salviati, Courtney E French, Andriy Shatillo, F Lucy Raymond, Tobias B Haack, Susana Quijano-Roy, Johann Böhm, Isabelle Nelson, Tanya Stojkovic, Teresinha Evangelista, Volker Straub, Norma B Romero, Jocelyn Laporte, Francesco Muntoni, Ichizo Nishino, Mark A Tarnopolsky, James Shorter, Carsten G Bönnemann, J Paul Taylor

Department of Biochemistry and Molecular Biology Faculty Papers

Missense variants in RNA-binding proteins (RBPs) underlie a spectrum of disease phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, and inclusion body myopathy. Here, we present ten independent families with a severe, progressive muscular dystrophy, reminiscent of oculopharyngeal muscular dystrophy (OPMD) but of much earlier onset, caused by heterozygous frameshift variants in the RBP hnRNPA2/B1. All disease-causing frameshift mutations abolish the native stop codon and extend the reading frame, creating novel transcripts that escape nonsense-mediated decay and are translated to produce hnRNPA2/B1 protein with the same neomorphic C-terminal sequence. In contrast to previously reported disease-causing missense variants in HNRNPA2B1, these frameshift …

A Periplasmic Cinched Protein Is Required For Siderophore Secretion And Virulence Of Mycobacterium Tuberculosis., Lei Zhang, James E Kent, Meredith Whitaker, David C Young, Dominik Herrmann, Alexander E Aleshin, Ying-Hui Ko, Gino Cingolani, Jamil S Saad, D Branch Moody, Francesca M Marassi, Sabine Ehrt, Michael Niederweis

Department of Biochemistry and Molecular Biology Faculty Papers

Iron is essential for growth of Mycobacterium tuberculosis, the causative agent of tuberculosis. To acquire iron from the host, M. tuberculosis uses the siderophores called mycobactins and carboxymycobactins. Here, we show that the rv0455c gene is essential for M. tuberculosis to grow in low-iron medium and that secretion of both mycobactins and carboxymycobactins is drastically reduced in the rv0455c deletion mutant. Both water-soluble and membrane-anchored Rv0455c are functional in siderophore secretion, supporting an intracellular role. Lack of Rv0455c results in siderophore toxicity, a phenotype observed for other siderophore secretion mutants, and severely impairs replication of M. tuberculosis in mice, demonstrating …