Medicine and Health Sciences Commons^™

Elucidation Of Molecular Kinetic Schemes From Macroscopic Traces Using System Identification, Miguel Fribourg, Diomedes E. Logothetis, Javier González-Maeso, Stuart C. Sealfon, Belén Galocha-Iragüen, Fernando Las-Heras Andrés, Vladimir Brezina

Physiology and Biophysics Publications

Overall cellular responses to biologically-relevant stimuli are mediated by networks of simpler lower-level processes. Although information about some of these processes can now be obtained by visualizing and recording events at the molecular level, this is still possible only in especially favorable cases. Therefore the development of methods to extract the dynamics and relationships between the different lower-level (microscopic) processes from the overall (macroscopic) response remains a crucial challenge in the understanding of many aspects of physiology. Here we have devised a hybrid computational-analytical method to accomplish this task, the SYStems-based MOLecular kinetic scheme Extractor (SYSMOLE). SYSMOLE utilizes system-identification input-output …

Aerobic Fitness Impacts Sympathoadrenal Axis Responses To Concurrent Challenges, Heather E. Webb, Deena A. Rosalky, Matthew J. Mcallister, Edmund O. Acevedo, Gary H. Kamimori

Physiology and Biophysics Publications

The combination of mental and physical challenges can elicit exacerbated cardiorespiratory (CR) and catecholamine responses above that of a single challenge alone.

Purpose

This study examined the effects of a combination of acute mental challenges and physical stress on cardiorespiratory and catecholamine responses.

Method

Eight below-average fitness (LF VO2max = 36.58 +/- 3.36 ml(-1) kg(-1) min(-1)) and eight above-average fitness (HF VO2max = 51.18 +/- 2.09 ml(-1) kg(-1) min(-1)) participants completed an exercise-alone condition (EAC) session consisting of moderate-intensity cycling at 60% VO2max for 37 min, and a dual-challenge condition (DCC) that included concurrent participation in mental challenges while cycling. …

Liver Adiposity And Metabolic Profile In Individuals With Chronic Spinal Cord Injury, Kathleen C. Rankin, Laura C. O’Brien, Liron Segal, M. Rehan Khan, Ashraf S. Gorgey

Physiology and Biophysics Publications

Purpose. To quantify liver adiposity using magnetic resonance imaging (MRI) and to determine its association with metabolic profile in men with spinal cord injury (SCI). Materials and Methods. MRI analysis of liver adiposity by fat signal fraction (FSF) and visceral adipose tissue (VAT) was completed on twenty participants. Intravenous glucose tolerance test was conducted to measure glucose effectiveness (𝑆g) and insulin sensitivity (𝑆i ). Lipid panel, fasting glucose, glycated hemoglobin (HbA1c), and inflammatory cytokines were also analyzed. Results. Average hepatic FSF was 3.7% ± 2.1. FSF was positively related to TG, non-HDL-C, fasting glucose, HbA1c, VAT, and …

Cyclic-Amp Regulates Postnatal Development Of Neural And Behavioral Responses To Nacl In Rats, Jie Qian, Shobha Mummalaneni, Tam-Hao T. Phan, Gerard L. Heck, John A. Desimone, David West, Sunila Mahavadi, Deanna Hojati, Karnam S. Murthy, Mee-Ra Rhyu, Andrew I. Spielman, Mehmet H. Özdener, Vijay Lyall

Physiology and Biophysics Publications

During postnatal development rats demonstrate an age-dependent increase in NaCl chorda tympani (CT) responses and the number of functional apical amiloride-sensitive epithelial Na+channels (ENaCs) in salt sensing fungiform (FF) taste receptor cells (TRCs). Currently, the intracellular signals that regulate the postnatal development of salt taste have not been identified. We investigated the effect of cAMP, a downstream signal for arginine vasopressin (AVP) action, on the postnatal development of NaCl responses in 19–23 day old rats. ENaC-dependent NaCl CT responses were monitored after lingual application of 8-chlorophenylthio-cAMP (8-CPT-cAMP) under open-circuit conditions and under ±60 mV lingual voltage clamp. Behavioral responses were …

Rnaseq Analyses Identify Tumor Necrosis Factor-Mediated Inflammation As A Major Abnormality In Als Spinal Cord, David G. Brohawn, Laura C. O'Brien, James P. Bennett Jr.

Physiology and Biophysics Publications

ALS is a rapidly progressive, devastating neurodegenerative illness of adults that produces disabling weakness and spasticity arising from death of lower and upper motor neurons. No meaningful therapies exist to slow ALS progression, and molecular insights into pathogenesis and progression are sorely needed. In that context, we used high-depth, next generation RNA sequencing (RNAseq, Illumina) to define gene network abnormalities in RNA samples depleted of rRNA and isolated from cervical spinal cord sections of 7 ALS and 8 CTL samples. We aligned >50 million 2X150 bp paired-end sequences/sample to the hg19 human genome and applied three different algorithms (Cuffdiff2, DEseq2, …

Nicotine-Induced Effects On Nicotinic Acetylcholine Receptors (Nachrs), Ca2+ And Brain-Derived Neurotrophic Factor (Bdnf) In Stc-1 Cells, Jie Qian, Shobha K. Mummalaneni, Reem M. Alkahtan, Sunila Mahavadi, Karnam S. Murthy, John R. Grider, Vijay Lyall

Physiology and Biophysics Publications

In addition to the T2R bitter taste receptors, neuronal nicotinic acetylcholine receptors (nAChRs) have recently been shown to be involved in the bitter taste transduction of nicotine, acetylcholine and ethanol. However, at present it is not clear if nAChRs are expressed in enteroendocrine cells other than beta cells of the pancreas and enterochromaffin cells, and if they play a role in the synthesis and release of neurohumoral peptides. Accordingly, we investigated the expression and functional role of nAChRs in enteroendocrine STC-1 cells. Our studies using RT-PCR, qRT-PCR, immunohistochemical and Western blotting techniques demonstrate that STC-1 cells express several α and …

Molecular Overlap In The Regulation Of Sk Channels By Small Molecules And Phosphoinositides, Miao Zhang, Xuan-Yu Meng, Ji-Fang Zhang, Meng Cui, Diomedes E. Logothetis

Physiology and Biophysics Publications

Phosphatidylinositol 4,5-bisphosphate (PIP2) directly interacts with the small-conductance Ca2+-activated K+2-a (SK2-a) channel/calmodulin complex, serving as a critical element in the regulation of channel activity. We report that changes of protein conformation in close proximity to the PIP2 binding site induced by a small-molecule SK channel modulator, NS309, can effectively enhance the interaction between the protein and PIP2 to potentiate channel activity. This novel modulation of PIP2 sensitivity by small-molecule drugs is likely not to be limited in its application to SK channels, representing an intriguing strategy to develop drugs controlling the activity of the large number of PIP2-dependent proteins.

Impact Of V-Ets Erythroblastosis Virus E26 Oncogene Homolog 1 Gene Polymorphisms Upon Susceptibility To Autoimmune Diseases, Ye Zhou, Miao Liu, Jun Li, Fiza Hashmi, Zhi Mao, Ning Zhang, Liang Zhou, Weiran Lv, Jingwei Zheng, Xiaoli Nie, Changzheng Li

Physiology and Biophysics Publications

V-ets erythroblastosis virus E26 oncogene homolog 1 (ETS1) is recognized as a gene of risk to autoimmune diseases (ADs). Two single nucleotide polymorphisms (SNPs) in ETS1 (rs1128334 G>A and rs10893872 T>C) were considered associated with ADs risk. However, the results remain conflicting.

We performed a meta-analysis to evaluate more precise estimations of any relationship. We searched PubMed, OvidSP, and Chinese National Knowledge Infrastructure databases (papers published prior to September 12, 2014) and extracted data from eligible studies. Meta-analysis was performed using the STATA 12.0 software. Random effect model or fixed effect model were chosen according to …

Editorial: Phosphoinositides And Their Phosphatases: Linking Electrical And Chemical Signals In Biological Processes, Susy C. Kohout, Carlos A. Villalba-Galea

Physiology and Biophysics Publications

The voltage-sensing phosphatase (VSP) has changed the way we think about both cellular electrical activity and PIPs (phosphatidylinositol phosphates). Originally discovered in 1999 (Chen et al., 1999), these proteins were not recognized as electrically-controlled enzymes until 2005 (Murata et al., 2005). They constitute the first, and so far the only, example of an enzyme linking electrical signals at the plasma membrane to the catalysis of PIPs (Murata et al., 2005), a ubiquitous family of intracellular signaling molecules (Di Paolo and De Camilli, 2006; Balla, 2013). Before the discovery of VSP, there were no known direct links between the two. Textbook …

A Rapid In Vivo Screen For Pancreatic Ductal Adenocarcinoma Therapeutics, Ozhan Ocal, Victor Pashkov, Rahul K. Kollipara, Yalda Zolghadri, Victoria H. Cruz, Michael A. Hale, Blake R. Heath, Alex B. Artyukhin, Alana L. Christie, Pantelis Tsoulfas, James B. Lorens, Galvin H. Swift, Rolf A. Brekken, Thomas M. Wilkie

Physiology and Biophysics Publications

Pancreatic ductal adenocarcinoma (PDA) is the fourth leading cause of cancer-related deaths in the United States, and is projected to be second by 2025. It has the worst survival rate among all major cancers. Two pressing needs for extending life expectancy of affected individuals are the development of new approaches to identify improved therapeutics, addressed herein, and the identification of early markers. PDA advances through a complex series of intercellular and physiological interactions that drive cancer progression in response to organ stress, organ failure, malnutrition, and infiltrating immune and stromal cells. Candidate drugs identified in organ culture or cell-based screens …

Identification Of The Conformational Transition Pathway In Pip2 Opening Kir Channels, Junwei Li, Shouqin Lü, Yuzhi Liu, Chunli Pang, Yafei Chen, Suhua Zhang, Hui Yu, Mian Long, Hailin Zhang, Diomedes E. Logothetis, Yong Zhan, Hailong An

Physiology and Biophysics Publications

The gating of Kir channels depends critically on phosphatidylinositol 4,5-bisphosphate (PIP2), but the detailed mechanism by which PIP2regulates Kir channels remains obscure. Here, we performed a series of Targeted molecular dynamics simulations on the full-length Kir2.1 channel and, for the first time, were able to achieve the transition from the closed to the open state. Our data show that with the upward motion of the cytoplasmic domain (CTD) the structure of the C-Linker changes from a loop to a helix. The twisting of the C-linker triggers the rotation of the CTD, which induces a small downward movement of the CTD …

Nicotinic Acetylcholine Receptor (Nachr) Dependent Chorda Tympani Taste Nerve Responses To Nicotine, Ethanol And Acetylcholine, Zuo Jun Ren, Shobha Mummalaneni, Jie Qian, Clive M. Baumgarten, John A. Desimone, Vijay Lyall

Physiology and Biophysics Publications

Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and …

Starvation-Induced Collective Behavior In C. Elegans, Alexander B. Artyukhin, Virginia Commonwealth University J. Yim, Mi Cheong Cheong, Leon Avery

Physiology and Biophysics Publications

We describe a new type of collective behavior in C. elegans nematodes, aggregation of starved L1 larvae. Shortly after hatching in the absence of food, L1 larvae arrest their development and disperse in search for food. In contrast, after two or more days without food, the worms change their behavior—they start to aggregate. The aggregation requires a small amount of ethanol or acetate in the environment. In the case of ethanol, it has to be metabolized, which requires functional alcohol dehydrogenase sodh-1. The resulting acetate is used in de novo fatty acid synthesis, and some of the newly made fatty …

Endogenous Bdnf Augments Nmda Receptor Phosphorylation In The Spinal Cord Via Plcγ, Pkc, And Pi3k/Akt Pathways During Colitis, Miao Liu, Jarren C. Kay, Shanwei Shen, Li-Ya Qiao

Physiology and Biophysics Publications

Background

Spinal central sensitization is an important process in the generation and maintenance of visceral hypersensitivity. The release of brain-derived neurotrophic factor (BDNF) from the primary afferent neurons to the spinal cord contributes to spinal neuronal plasticity and increases neuronal activity and synaptic efficacy. The N-Methyl-D-aspartic acid (NMDA) receptor possesses ion channel properties, and its activity is modulated by phosphorylation of its subunits including the NMDA receptor 1 (NR1).

Methods

Colonic inflammation was induced by a single dose of intracolonic instillation of tri-nitrobenzene sulfonic acid (TNBS). NR1 phosphorylation by BDNF in vivo and in culture was examined by western …

Nicotinic Acetylcholine Receptor (Nachr) Dependent Chorda Tympani Taste Nerve Responses To Nicotine, Ethanol And Acetylcholine, Zuo Jun Ren, Shobha Mummalaneni, Jie Qian, Clive M. Baumgarten, John A. Desimone, Vijay Lyall

Physiology and Biophysics Publications

Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and …

A Multilaboratory Comparison Of Calibration Accuracy And The Performance Of External References In Analytical Ultracentrifugation, Huaying Zhao, Rodolfo Ghirlando, Carlos Alfonso, Fumio Arisaka, Ilan Attali, David L. Bain, Marina M. Bakhtina, Donald F. Becker, Gregory J. Bedwell, Ahmet Bekdemir, Tabot M. D. Besong, Catherine Birck, Chad A. Brautigam, William Brennerman, Olwyn Byron, Agnieszka Bzowska, Jonathan B. Chaires, Catherine T. Chaton, Helmut Cölfen, Keith D. Connaghan, Kimberly A. Crowley, Ute Curth, Tina Daviter, William L. Dean, Ana I. Díez, Christine Ebel, Debra M. Eckert, Leslie E. Eisele, Edward Eisenstein, Patrick England, Carlos Escalante, Jeffrey A. Fagan, Robert Fairman, Ron M. Finn, Wolfgang Fischle, José García De La Torre, Jayesh Gor, Henning Gustafsson, Damien Hall, Stephen E. Harding, José G. Hernández Cifre, Andrew B. Herr, Elizabeth E. Howell, Richard S. Isaac, Shu-Chuan Jao, Davis Jose, Soon-Jong Kim, Bashkim Kokona, Jack A. Kornblatt, Dalibor Kosek, Elena Krayukhina, Daniel Krzizike, Eric A. Kusznir, Hyewon Kwon, Adam Larson, Thomas M. Laue, Aline Le Roy, Andrew P. Leech, Hauke Lilie, Karolin Lugar, Juan R. Luque-Ortega, Jia Ma, Carrie A. May, Ernest L. Maynard, Anna Modrak-Wojcik, Yee-Foong Mok, Norbert Mücke, Luitgard Nagel-Steger, Geeta J. Narlikar, Masanori Noda, Amanda Nourse, Tomas Obsil, Chad K. Park, Jin-Ku Park, Peter D. Pawelek, Erby E. Perdue, Stephen J. Perkins, Matthew A. Perugini, Craig L. Peterson, Martin G. Peverelli, Grzegorz Piszczek, Gali Prag, Peter E. Prevelige, Bertrand D. E. Raynal, Lenka Rezabkova, Klaus Richter, Alison E. Ringel, Rose Rosenberg, Arthur J. Rowe, Arne C. Rufer, David J. Scott, Javier G. Seravalli, Alexandra S. Solovyova, Renjie Song, David Staunton, Catlin Stoddard, Katherine Stott, Holger M. Strauss, Werner W. Streicher, John P. Sumida, Sarah G. Swygert, Roman H. Szczepanowski, Ingrid Tessmer, Ronald T. Toth Iv., Ashutosh Tripathy, Susumu Uchiyama, Stephen F. W. Uebel, Satoru Unzai, Anna Vitlin Gruber, Peter H. Von Hippel, Christine Wandrey, Szu-Huan Wang, Steven E. Weitzel, Beata Wielgus-Kutrowska, Cynthia Wolberger, Martin Wolff, Edward Wright, Yu-Sung Wu, Jacinta M. Wubben, Peter Schuck

Physiology and Biophysics Publications

Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy …

An Opioid-Like System Regulating Feeding Behavior In C. Elegans, Mi Cheong Cheong, Alexander B. Artyukhin, Yong-Jai You, Leon Avery

Physiology and Biophysics Publications

Neuropeptides are essential for the regulation of appetite. Here we show that neuropeptides could regulate feeding in mutants that lack neurotransmission from the motor neurons that stimulate feeding muscles. We identified nlp-24 by an RNAi screen of 115 neuropeptide genes, testing whether they affected growth. NLP-24 peptides have a conserved YGGXX sequence, similar to mammalian opioid neuropeptides. In addition, morphine and naloxone respectively stimulated and inhibited feeding in starved worms, but not in worms lacking NPR-17, which encodes a protein with sequence similarity to opioid receptors. Opioid agonists activated heterologously expressed NPR-17, as did at least one NLP-24 peptide. Worms …

Starvation-Induced Collective Behavior In C. Elegans, Alex B. Artyukhin, Joshua J. Yim, Mi Cheong Cheong, Leon Avery

Physiology and Biophysics Publications

We describe a new type of collective behavior in C. elegans nematodes, aggregation of starved L1 larvae. Shortly after hatching in the absence of food, L1 larvae arrest their development and disperse in search for food. In contrast, after two or more days without food, the worms change their behavior—they start to aggregate. The aggregation requires a small amount of ethanol or acetate in the environment. In the case of ethanol, it has to be metabolized, which requires functional alcohol dehydrogenase sodh-1. The resulting acetate is used in de novo fatty acid synthesis, and some of the newly made …

A Model Of The Effect Of Uncertainty On The C Elegans L2/L2d Decision, Leon Avery

Physiology and Biophysics Publications

Abstract

At the end of the first larval stage, the C elegans larva chooses between two developmental pathways, an L2 committed to reproductive development and an L2d, which has the option of undergoing reproductive development or entering the dauer diapause. I develop a quantitative model of this choice using mathematical tools developed for pricing financial options. The model predicts that the optimal decision must take into account not only the expected potential for reproductive growth, but also the uncertainty in that expected potential. Because the L2d has more flexibility than the L2, it is favored in unpredictable environments. I estimate …

Effect Of Enac Modulators On Rat Neural Responses To Nacl, Shobha Mummalaneni, Jie Qian, Tam-Hao T. Phan, Mee-Ra Rhyu, Gerard L. Heck, John A. Desimone, Vijay Lyall

Physiology and Biophysics Publications

The effects of small molecule ENaC activators N,N,N-trimethyl-2-((4-methyl-2-((4-methyl-1H-indol-3-yl)thio)pentanoyl)oxy)ethanaminiumiodide (Compound 1) and N-(2-hydroxyethyl)-4-methyl-2-((4-methyl-1H-indol-3-yl)thio)pentanamide(Compound 2), were tested on the benzamil (Bz)-sensitive NaCl chorda tympani (CT) taste nerve response under open-circuit conditions and under ±60 mV applied lingual voltage-clamp, and compared with the effects of known physiological activators (8-CPT-cAMP, BAPTA-AM, and alkaline pH), and an inhibitor (ionomycin+Ca2+) of ENaC. The NaCl CT response was enhanced at −60 mV and suppressed at +60 mV. In every case the CT response (r) versus voltage (V) curve was linear. All ENaC activators increased the open-circuit response (ro) and the voltage …

Selective Activation Of Htrpv1 By N-Geranyl Cyclopropylcarboxamide, An Amiloride-Insensitive Salt Taste Enhancer, Min Jung Kim, Hee Jin Son, Yiseul Kim, Hae-Jin Kweon, Byung-Chang Suh, Vijay Lyall, Mee-Ra Rhyu

Physiology and Biophysics Publications

TRPV1t, a variant of the transient receptor potential vanilloid-1 (TRPV1) has been proposed as a constitutively active, non-selective cation channel as a putative amiloride-insensitive salt taste receptor and shares many properties with TRPV1. Based on our previous chorda tympani taste nerve recordings in rodents and human sensory evaluations, we proposed that N-geranylcyclopropylcarboxamide (NGCC), a novel synthetic compound, acts as a salt taste enhancer by modulating the amiloride/benzamil-insensitive Na+ entry pathways. As an extension of this work, we investigated NGCC-induced human TRPV1 (hTRPV1) activation using a Ca2+-flux signaling assay in cultured cells. NGCC enhanced Ca2+ influx in hTRPV1-expressing cells in …

Lack Of Negatively Charged Residues At The External Mouth Of Kir2.2 Channels Enable The Voltage-Dependent Block By External Mg2+, Junwei Li, Xiaoxiao Xie, Jun Liu, Hui Yu, Suhua Zhang, Yong Zhan, Hailin Zhang, Diomedes E. Logothetis, Hailong An

Physiology and Biophysics Publications

Kir channels display voltage-dependent block by cytosolic cations such as Mg2+ and polyamines that causes inward rectification. In fact, cations can regulate K channel activity from both the extracellular and intracellular sides. Previous studies have provided insight into the up-regulation of Kir channel activity by extracellular K+ concentration. In contrast, extracellular Mg2+ has been found to reduce the amplitude of the single-channel current at milimolar concentrations. However, little is known about the molecular mechanism of Kir channel blockade by external Mg2+ and the relationship between the Mg2+ blockade and activity potentiation by permeant K+ ions. In this study, we applied …

Suppression Of The Pi3k Pathway In Vivo Reduces Cystitis-Induced Bladder Hypertrophy And Restores Bladder Capacity Examined By Magnetic Resonance Imaging, Zhongwei Qiao, Chunmei Xia, Shanwei Shen, Frank D. Corwin, Miao Liu, Ruijuan Guan, John R. Grider, Li-Ya Qiao

Physiology and Biophysics Publications

This study utilized magnetic resonance imaging (MRI) to monitor the real-time status of the urinary bladder in normal and diseased states following cyclophosphamide (CYP)-induced cystitis, and also examined the role of the phosphoinositide 3-kinase (PI3K) pathway in the regulation of urinary bladder hypertrophy in vivo. Our results showed that under MRI visualization the urinary bladder wall was significantly thickened at 8 h and 48 h post CYP injection. The intravesical volume of the urinary bladder was also markedly reduced. Treatment of the cystitis animals with a specific PI3K inhibitor LY294002 reduced cystitis-induced bladder wall thickening and enlarged the intravesical volumes. …

Wicking: A Rapid Method For Manually Inserting Ion Channels Into Planar Lipid Bilayers, Justin A. Costa, Dac A. Nguyen, Egdar Leal-Pinto, Ronald E. Gordon, Basil Hanss

Physiology and Biophysics Publications

The planar lipid bilayer technique has a distinguished history in electrophysiology but is arguably the most technically difficult and time-consuming method in the field. Behind this is a lack of experimental consistency between laboratories, the challenges associated with painting unilamellar bilayers, and the reconstitution of ion channels into them. While there has be a trend towards automation of this technique, there remain many instances where manual bilayer formation and subsequent membrane protein insertion is both required and advantageous. We have developed a comprehensive method, which we have termed “wicking”, that greatly simplifies many experimental aspects of the lipid bilayer system. …

In Vivo Regulation Of Brain-Derived Neurotrophic Factor In Dorsal Root Ganglia Is Mediated By Nerve Growth Factor-Triggered Akt Activation During Cystitis, Li-Ya Qiao, Sharon Yu, Jarren C. Kay, Chun-Mei Xia

Physiology and Biophysics Publications

Abstract

The role of brain-derived neurotrophic factor (BDNF) in sensory hypersensitivity has been suggested; however the molecular mechanisms and signal transduction that regulate BDNF expression in primary afferent neurons during visceral inflammation are not clear. Here we used a rat model of cystitis and found that the mRNA and protein levels of BDNF were increased in the L6 dorsal root ganglia (DRG) in response to bladder inflammation. BDNF up-regulation in the L6 DRG was triggered by endogenous nerve growth factor (NGF) because neutralization of NGF with a specific NGF antibody reduced BDNF levels during cystitis. The neutralizing NGF antibody also …

S3-S4 Linker Length Modulates The Relaxed State Of A Voltage-Gated Potassium Channel, Michael F. Priest, Jérôme J. Lacroix, Carlos A. Villalba-Galea, Fancisco Bezanilla

Physiology and Biophysics Publications

Abstract

Voltage-sensing domains (VSDs) are membrane protein modules found in ion channels and enzymes that are responsible for a large number of fundamental biological tasks, such as neuronal electrical activity. The VSDs switch from a resting to an active conformation upon membrane depolarization, altering the activity of the protein in response to voltage changes. Interestingly, numerous studies describe the existence of a third distinct state, called the relaxed state, also populated at positive potentials. Although some physiological roles for the relaxed state have been suggested, little is known about the molecular determinants responsible for the development and modulation of VSD …

Distinctive G Protein-Dependent Signaling By Protease-Activated Receptor 2 (Par2) In Smooth Muscle: Feedback Inhibition Of Rhoa By Camp-Independent Pka, Wimolpak Sriwai, Sunila Mahavadi, Othman Al-Shboul, John R. Grider, Karnam S. Murthy

Physiology and Biophysics Publications

We examined expression of protease-activated receptors 2 (PAR2) and characterized their signaling pathways in rabbit gastric muscle cells. The PAR2 activating peptide SLIGRL (PAR2-AP) stimulated Gq, G13, Gi1, PI hydrolysis, and Rho kinase activity, and inhibited cAMP formation. Stimulation of PI hydrolysis was partly inhibited in cells expressing PAR2 siRNA, Gaq or Gai minigene and in cells treated with pertussis toxin, and augmented by expression of dominant negative regulator of G protein signaling (RGS4(N88S)). Stimulation of Rho kinase activity was abolished by PAR-2 or Ga13 siRNA, and by Ga13 minigene. PAR2-AP induced a biphasic contraction; initial contraction was …

Building Kcnq1/Kcne1 Channel Models And Probing Their Interactions By Molecular-Dynamics Simulations, Yu Xu, Yuhong Wang, Xuan-Yu Meng, Mei Zhang, Min Jiang, Meng Cui, Gea-Ny Tseng

Physiology and Biophysics Publications

The slow delayed rectifier (I_Ks) channel is composed of KCNQ1 (pore-forming) and KCNE1 (auxiliary) subunits, and functions as a repolarization reserve in the human heart. Design of I_Ks-targeting anti-arrhythmic drugs requires detailed three-dimensional structures of the KCNQ1/KCNE1 complex, a task made possible by Kv channel crystal structures (templates for KCNQ1 homology-modeling) and KCNE1 NMR structures. Our goal was to build KCNQ1/KCNE1 models and extract mechanistic information about their interactions by molecular-dynamics simulations in an explicit lipid/solvent environment. We validated our models by confirming two sets of model-generated predictions that were independent from the spatial restraints used …

Mekk1-Mkk4-Jnk-Ap1 Pathway Negatively Regulates Rgs4 Expression In Colonic Smooth Muscle Cells, Yonggang Zhang, Fang Li, Shu Liu, Hong Wang, Sunila Mahavadi, Karnam S. Murthy, Kamel Khalili, Wenhui Hu

Physiology and Biophysics Publications

Background

Regulator of G-protein Signaling 4 (RGS4) plays an important role in regulating smooth muscle contraction, cardiac development, neural plasticity and psychiatric disorder. However, the underlying regulatory mechanisms remain elusive. Our recent studies have shown that upregulation of Rgs4 by interleukin (IL)-1β is mediated by the activation of NFκB signaling and modulated by extracellular signal-regulated kinases, p38 mitogen-activated protein kinase, and phosphoinositide-3 kinase. Here we investigate the effect of the c-Jun N-terminal kinase (JNK) pathway on Rgs4 expression in rabbit colonic smooth muscle cells.

Methodology/Principal Findings

Cultured cells at first passage were treated with or without IL-1β …

The Interdomain Linker Of Aav-2 Rep68 Is An Integral Part Of Its Oligomerization Domain: Role Of A Conserved Sf3 Helicase Residue In Oligomerization, Francisco Zarate-Perez, Martino Bardelli, John W. Burgner Ii, Maria Villamil-Jarauta, Kanni Das, Demet Kekilli, Jorge Mansilla-Soto, R. Michael Linden, Carlos R. Escalante

Physiology and Biophysics Publications

The four Rep proteins of adeno-associated virus (AAV) orchestrate all aspects of its viral life cycle, including transcription regulation, DNA replication, virus assembly, and site-specific integration of the viral genome into the human chromosome 19. All Rep proteins share a central SF3 superfamily helicase domain. In other SF3 members this domain is sufficient to induce oligomerization. However, the helicase domain in AAV Rep proteins (i.e. Rep40/Rep52) as shown by its monomeric characteristic, is not able to mediate stable oligomerization. This observation led us to hypothesize the existence of an as yet undefined structural determinant that regulates Rep oligomerization. In this …