bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aldosterone Alters Chromatin Structure of the Murine Endothelin‐1 Gene
Authors: Welch Amanda Kuhns , Jacobs Mollie E. , Lynch I. Jeanette , Gumz Michelle L. , Cain Brian D. , Wingo Charles S. 
Published: June 2021

Aldosterone (Aldo) increases sodium (Na) reabsorption in the renal collecting duct (CD) and systemic blood pressure. We have shown that Aldo induces transcription of the endothelin‐1 (Edn1) gene and increases protein (ET‐1) levels (JBC 2009;294:30087). Since ET‐1 inhibits the action of Aldo on CD Na reabsorption, we hypothesize that ET‐1 acts in a negative feedback loop on Na retention. Whereas transcriptional regulation of the Edn1 gene has been investigated, the importance of epigenetic Edn1 gene regulation is largely unexplored. Here we examine the effect of Aldo on chromatin structure of the Edn1 gene. We used a novel quantitative PCR‐based DNaseI hypersensitivity assay of chromatin structure in 4 regions of the Edn1 gene known to affect transcription in murine inner medullary collecting duct‐3 cells. The calcium‐responsive element (NFAT) (JBC 2010;285:28520) at −1263 bp has low chromatin accessibility under all conditions tested. However, the NFAT element at −1563 bp upstream has low accessibility and is significantly more accessible in cells exposed to Aldo.The distal Aldo hormone response element (HRE2) is highly accessible under all conditions tested. However, Aldo caused a significant increase in chromatin accessibility of the more proximal promotor including HRE1. The results extend our previous observations and suggest that Aldo activation of the mineralocorticoid receptor (MR) results in MR binding at HRE2 to open chromatin structure of specific regions of the Edn1 gene.This work was funded by National Public Health Service Grant no. R01 DK82680 to CSW and BDC.
Mechanoprotection by Polycystins Against Apoptosis is Mediated Through the Opening of Stretch‐Activated K2P Channels
Authors: Duprat Fabrice , Peyronnet Remi , Sharif‐Naeini Reza , Folgering Joost H.A. , Arhatte Malika , Jodar Martine , El Boustany Charbel , Gallian Claire , Tauc Michel , Duranton Christophe , Rubera Isabelle , Lesage Florian , Pei York , Peters Dorien , Somlo Stefan , Sachs Frederick , Patel Amanda Jane , Honoré Eric 
Published: June 2021

How cells sense and adapt to mechanical stress remains poorly understood. The TREK two‐pore K+ (K2P) subunits underlie the stretch‐activated K+‐selective channels (SAKs). Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in either PKD1 or PKD2 genes, encoding the polycystins PC1 and PC2. Cystogenesis results mainly from an increase in tubular epithelial cells proliferation. Nevertheless, how a few cysts (typically less than 1% of the nephrons) may impair the function of the majority (99%) of non‐cystic nephrons, ultimately leading to kidney failure, is still an unresolved question. An increase in intra‐renal mechanical stress leading to tubular cells apoptosis and formation of atubular nephrons is a proposed mechanism.In our study, Pkd1 knock out or expression of a PC2 pathogenic mutant enhances tubular cells apoptosis induced by mechanical stress. We show that polycystins protect renal epithelial cells against mechanical stress and this effect is mediated through the opening of SAKs. We establish for the first time, both in vitro and in vivo, a functional relationship between mechanotransduction and mechanoprotection (Peyronnet et al. 2012 Cell Rep 1(3): 241–250).Funding: ANR, FRM, EEC, FRHTA, FRC, Human Frontier, Fondation de France, AFM, AIRG, Région PACA, SFHTA.
REGULATION OF GLOMERULOTUBULAR BALANCE IV: IMPLICATION OF AQUAPORIN 1 IN FLOW‐DEPENDENT TRANSPORT AND CELL VOLUME
Authors: Du Zhaopeng , Yan Qingshang , Weinbaum Sheldon , Weinstein Alan M , Wang Tong 
Published: June 2021

Underlying glomerulortubular balance (GTB) is the impact of axial flow to regulate Na+ and HCO3− transport by modulating luminal NHE3 and H‐ATPase, and presumably other peritubular transporters, since there is little flow‐dependent change in cell volume. Aquaporin (AQP‐1) serves as a water channel and is the principal water pathway for luminal and peritubular membranes of proximal tubule. We investigated flow‐mediated fluid (Jv) and HCO3− (JHCO3) absorption in proximal tubules (S2) of mouse kidney by microperfusion in vitro in wild‐type (WT) and AQP‐1 KO mice.

Perfusion
Tubule No.
Jv (nl/min/mm)
JHCO3 (pmol/min/mm)
Cell Volume (μm3)

(nl/min)
WT
KO
WT
KO
WT
KO
WT
KO

5
31
9
0.79±0.04
0.57±0.06†
56.3±3.1
61±5.9
1027
1034

20
10
18
1.37±0.06*
0.38±0.03*†
116±7.5*
133±7.8*
1001
946

P<0.05 compared from low flow rate;
P<0.05 compared between WT and KO at same flow rate.

An increase in perfusion rate from 5 to 20 nl/min increased Jv by 73% and JHCO3 by 106% in proximal tubules of WT mice (P<0.001). Compared with WT, AQP‐1 KO significantly decreased Jv at both low and high flow rates (P<0.05), and there was actually a decrease in volume flux in the transition from low to high flow (P<0.05). In contrast, the AQP‐1 KO mice showed no difference from WT in JHCO3 at either low or high flow rates. Cell volume showed no significant difference between either low or high flow rates or between WT and AQP‐1 KO mice. These results confirm the role of AQP‐1 as the principal pathway for water reabsorption in proximal tubule. The decrease in Jv with increasing perfusion rate is consistent with a model in which proximal Na+ reabsorption produces a transepithelial osmotic gradient, which then drives volume reabsorption. Whether axial flow increases AQP‐1 activity, remains uncertain. Flow‐stimulated Na+ and HCO3− absorption is independent of intact AQP‐1.
Interactions between sorting protein‐related receptor and calcineurin to activate renal Na‐K‐2Cl cotransporter
Authors: Mutig Kerim , Borschewski Aljona , Willnow Thomas , Dathe Christin , Paliege Alexander , Ferreri Nicholas , Bachmann Sebastian 
Published: June 2021

Activity of the Na‐K‐2Cl cotransporter (NKCC2) of thick ascending limb (TAL) depends on its phosphorylation. The sorting protein‐related receptor SORLA facilitates this process, but the underlying mechanism is still elusive. We hypothesized that SORLA may interfere with kinases or phosphatases relevant for NKCC2 phosphorylation.We have studied the regulation of the proline/alanine‐rich kinase (SPAK), oxidative stress responsive kinase 1 (OSR1), and calcineurin phosphatase A (CnA) in wildtype (WT) and SORLA‐deficient (SORLA−/−) kidneys in vivo and in cell culture.Knockdown of SPAK/OSR1 in cultured rat TAL cells decreased, whereas inhibition of calcineurin with cyclosporin A (CsA) increased NKCC2 phosphorylation thus confirming their relevance for the transporter. SORLA‐deficiency was associated with decreased NKCC2 phosphorylation (−84%), unchanged abundance and distribution of SPAK and OSR1 kinases, and increased abundance of CnAβ isoform in the apical compartment of TAL epithelia (+201%). Short term administration of CsA to SORLA−/− mice restored their decreased NKCC2 phosphorylation. Coimmunoprecipitations from rat kidney revealed interactions between CnAβ, NKCC2, and SORLA.Our results suggest that SORLA participates in calcineurin degradation in TAL thereby supporting activating phosphorylation of NKCC2.
ATP regulates Cl− and K+ channels in human pancreatic ducts
Authors: Novak Ivana , Wang Jing , Hayashi Mikio 
Published: June 2021

Pancreas is one of the major organs affected by cystic fibrosis. Purinergic receptors may provide novel strategies for up‐regulation of pancreatic secretion. Our aim was to elucidate how purineric receptors regulate ion transport in human pancreatic ducts and identify Cl− and K+ channels. Transepithelial transport was monitored in monolayers of Capan‐1 and CFPAC‐1 cells in Ussing chambers. Apical ATP/UTP stimulated CFTR and Ca2+‐activated Cl−channels, which were inhibited by CFTRinh‐172 and niflumic acid, respectively. Basolateral ATP stimulated CFTR. In CFPAC‐1 cells (with mutated CFTR), basolateral ATP/UTP had negligible effects. In Capan‐1 cells, effects of DC‐EBIO and clotrimazole indicated functional expression of the intermediate conductance K+ channels (IK, KCa3.1). Apical effects of ATP/UTP were greatly potentiated by IK opener DC‐EBIO. On mRNA and protein level we showed that Capan‐1 cells expressed TMEM16A/ANO1 and KCa3.1. We conclude that in human pancreatic duct cells, ATP/UTP regulates via P2 receptors both Cl− channels (ANO1 and CFTR) and K+ channels (KCa3.1). The K+ channels provide the driving force for Cl− channel‐dependent secretion, and luminal ATP provided locally or from acini potentiate secretory processes.Funded: the Lundbeck Foundation;The Danish Council for Independent Research | Natural Sciences
SKA‐111, a positive KCa channel gating modulator with selectivity for KCa3.1
Authors: Coleman Nichole , Brown Brandon , Jenkins Paul David , Köhler Ralf , Wulff Heike 
Published: June 2021

Intermediate‐conductance KCa3.1 and small‐conductance KCa2.3 channels are co‐expressed in vascular endothelium, where both channels contribute to endothelium‐derived hyperpolarization (EDH) vasodilator responses. However, despite having very similar biophysical properties, KCa3.1 and KCa2.3 seem to play different roles in EDH. While KCa3.1 channels are predominantly localized to endothelial cell projections and are activated by Ca2+ released from the ER, KCa2.3 channels co‐localize with TRP channels and have been shown to be involved in sheer‐stress induced vasodilation. It therefore is perceivable that selective activation of either channel could differentially affect endothelial functions and blood pressure. However, the currently available KCa channel activators like EBIO, NS309 and SKA‐31 at most display 5–10 fold selectivity for KCa3.1 over KCa2.3 making it difficult to interpret in vivo observations made with these compounds. We here report the design of a new benzothiazole, SKA‐111, which displays 160‐fold selectivity for KCa3.1 (EC50 = 30 nM) over KCa2.3 (EC50 = 5 μM) in whole‐cell patch‐clamp experiments. Similar to the prototypical KCa2/3 channel activator EBIO, SKA‐111 is a positive‐gating modulator, which shifts the calcium‐dose response curve of KCa3.1 to the left, making the channel apparently more sensitive to calcium activation. We propose SKA‐111 as a novel pharmacological tool to study the role of KCa3.1 in EDH responses.Supported by R21 NS072585 from the National Institute of Health
The deltaF508‐CFTR mutation alters the membrane distribution of DMT1 and ferroportin in human cystic fibrosis airway epithelial cells
Authors: Moreau‐Marquis Sophie , Coutermarsh Bonita A , Stanton Bruce A 
Published: June 2021

Iron homeostasis is abnormal in patients with cystic fibrosis (CF). Previously, we found that human CF bronchial epithelial cells expressing ΔF508‐CFTR (CFBE+ΔF508 cells), the most common mutation in CF, secrete more iron into the airway surface liquid than WT‐CFTR cells (CFBE+WT cells). Here we report that CFBE+ΔF508 cells express 2.5‐fold more DMT1, which transports iron into cells, and 6‐fold more FPN1, which transports iron out of cells, than CFBE+WT cells. In addition, selective cell surface biotinylation revealed that the ΔF508‐CFTR mutation leads to significant changes in the localization of these two major iron transporters. In CFBE+WT cells, DMT1 and FPN1 were distributed equally in both the apical and basolateral membrane. By contrast, in CFBE+ΔF508 cells, DMT1 polarized to the basolateral membrane (70/30%‐basolateral/apical) while FPN1 polarized to the apical membrane (86/14% apical/basolateral). This polarization of DMT1 and FPN1 can account for the increased transepithelial secretion of iron into the airway surface liquid of CF airway cells, and contribute to the enhanced iron levels in CF airways. To our knowledge, this is the first study reporting a link between the ΔF508‐CFTR mutation and iron transporters involved in iron homeostasis.Supported by NIH R01‐HL074175 and the CF Foundation (STANTO07R0).
Softening of hyperoxia treated alveolar epithelial cells reduces stretch‐induced injury
Authors: Wilhelm Kristina Rebecca , Roan Esra , Gosh Maik , Waters Christopher M. 
Published: June 2021

ObjectivesAcute respiratory distress syndrome (ARDS) patients are administered high concentrations of oxygen during mechanical ventilation; hyperoxia and mechanical ventilation can independently cause injury. The combination may even accelerate the injury, but how this injury occurs is still not fully understood. Here we show that stretch‐induced injury following hyperoxia is a function of cell elasticity (E).MethodsWe utilized an atomic force microscope (Asylum) in the indentation‐mode to measure E in cultured alveolar epithelial cells, and a cell‐stretch device to mimic mechanical ventilation. Cell detachment was determined following pre‐treatment with hyperoxia and subsequent cell stretching.ResultsHyperoxia increased cell elasticity of lung epithelial cells, thus making them more brittle and more susceptible to stretch‐induced injury (Roan et. al). Decreasing E (softening) the cells after hyperoxia treatment by inhibiting RhoA Kinase (Y‐27632), by decreasing f‐actin (cytochalasin D), or by reducing acto‐myosin contractility (blebbistatin) reduced subsequent stretched‐induced injury.ConclusionStretch‐induced injury in ARDS patients may be reduced by lowering the stiffness of cells.
Transient receptor potential cation channel vanilloid (TRPV) 4 in ventilator‐induced lung injury (VILI)
Authors: Michalick Laura , Mertens Michael , Liedtke Wolfgang , Kuebler Wolfgang Michael 
Published: June 2021

Study objectiveCa2+ entry via TRPV4 has been implicated in stretch‐induced barrier failure in isolated lungs. Here, we assessed the relevance of TRPV4 in VILI in vivo, and probed for the contribution of serum/glucocorticoid‐regulated kinase (SGK) 1, which phosphorylates TRPV4, and of Ca2+‐activated K+ channels (SK, BK) as putative signalling mechanisms upstream and downstream of TRPV4, respectively.MethodsMale, anesthetized mice were mechanically ventilated for 2 h by low (7 ml/kg) and high (20 ml/kg) tidal volumes (LVT/HVT) in wild type and TRPV4‐deficient mice, and following pharmacological inhibition of SGK1, TRPV4, SK or BK channels.ResultsTRPV4 deficiency or inhibition by HC‐067047 attenuated VILI as demonstrated by reduced lung edema, protein leak, MPO activity, inflammatory cytokine levels, and histological features of lung injury. Inhibition of SK or BK channels by apamin or charybdotoxin attenuated lung edema in HVT mice, yet only charybdotoxin had concomitant anti‐inflammatory effects. Lung edema formation in HVT mice was also largely reduced by the SGK1 inhibitor GSK650394.ConclusionsHere, we demonstrate the critical role of TRPV4 for VILI in vivo, and identify potential upstream (SGK1) and downstream (SK, BK) signalling events that may present putative pharmacological targets for the prevention or treatment of ventilator‐associated lung disease.
RGS5 is crucial for vascular smooth muscle cells during arterial remodeling in mice
Authors: Arnold Caroline , Feldner Anja , Genové Guillem , Wieland Thomas , Hecker Markus , Korff Thomas 
Published: June 2021

G protein‐coupled receptors (GPCR) are major regulators of contractility of vascular smooth muscle cells (SMCs) thereby controlling vascular tone, blood pressure and flow. GPCR signal transduction is modulated by the regulators of G protein signaling (RGS) which terminate G protein activation. Although RGS5 is known to inhibit Gαq activation in arterial SMCs, its role in arterial remodeling is unclear.To this end, we induced arteriogenesis – the flow and wall stress‐induced growth of collateral arterioles – in mice. Immunofluorescence analysis of remodeling arterioles showed increased RGS5 abundance in wild type medial SMCs while remodeling in rgs5−/− arterioles was disturbed. Exposing cultured human arterial SMCs to cyclic stretch, mimicking elevated wall stress, also led to increased RGS5 levels. Over‐expressing RGS5 in human arterial SMCs prevented Gαq/Ca2+‐mediated constriction upon sphingosine‐1‐phosphate (S1P) stimulation whereas S1P‐treated isolated rgs5−/− arteries showed enhanced contractility. This shifted S1P signaling from Gαq towards Gα12/13‐mediated RhoA kinase activation.In summary, elevated wall stress elicited RGS5 expression which blunts Ca2+‐mediated vasoconstriction leading to Gα12/13‐dependent RhoA kinase activation. This appears to be critical for arteriogenesis. This work was supported by the Deutsche Forschungsgemeinschaft (SFB TR23, projects B6/C5/C6).
Cardiac Sensory Consequences of Low‐Amplitude Autonomic Regulation Therapy
Authors: Ardell Jeffrey L , Beaumont Eric , Kenknight Bruce H , Gibbons David , Southerland Marie , Armour John Andrew 
Published: June 2021

ObjectiveTo determine if vagus nerve stimulation (VNS) or spinal cord stimulation (SCS) affects the capacity of cardiac afferent neurons to transduce myocardial ischemia (MI).MethodsUsing extracellular recordings in anesthetized canines, cardiac‐related dorsal root (DRG; T1‐T3 spinal levels) or nodose ganglia neurons were identified by touch/chemical activation in their epicardial sensory fields located adjacent to the left anterior descending (LAD) coronary artery. Neuronal responses to 1 min LAD coronary artery occlusion (CAO) were then evaluated prior to and following SCS [T1‐T3 spinal level; 50Hz, 90% motor threshold; 20 min] or left cervical VNS [20 Hz; current amplitudes (CA): CA1 (1–1.9 mA) or CA2 (2–3.5 mA); 3 min].ResultsLAD CAO activated cardiac afferent neurons in nodose and DRG ganglia, enhancement that persisted for up to 30 min into reperfusion. Following SCS or CA2 VNS, LAD CAO failed to alter their neural activity. VNS at CA1 did not mitigate MI‐induced activation of nodose neurons.ConclusionsTransient myocardial ischemia activates primary afferent inputs to the central nervous system (CNS), responses that persist into reperfusion. Pre‐emptive VNS or SCS obtunds sensory transduction of the ischemic myocardium to the CNS, in part accounting for the anti‐anginal and broader cardioprotective effects of such therapy being evaluated clinically. (HL71830)
The Effects of Sympathetic Nerve Stimulation on Ventricular Electrophysiology in Long QT Syndrome‐1
Authors: Brack Kieran , Winter James , Gupta Ayushman , Ng G. Andre 
Published: June 2021

Congenital long QT syndrome 1 (LQTS1) results from reduced slow activating delayed rectifier potassium channel (IKs) activity. Ventricular arrhythmias occur with increases in sympathetic tone which can cause sudden cardiac death (SCD). Underlying mechanisms are not understood but may include changes in electrical restitution (RT) – the relationship between action potential duration and diastolic interval. We aimed to examine the effects of sympathetic nerve stimulation (SNS) on effective refractory period (ERP), RT slope and inducibility of ventricular fibrillation (VF) in a pharmacological model of LQTS1. The innervated heart preparation from adult male guinea pigs (n=6, 450–550g) were used. ERP and LV apical and basal RT were measured using an extrastimulus protocol. Inducibility of VF was assessed with ventricular fibrillation threshold (VFT). Parameters were measured during baseline (BL) and SNS (3Hz, 1V) in control (Ctrl) and in the presence of the IKs blocker HMR1556 to mimic LQTS1 (HMR). Data are mean±SEM, analysed using Student's T‐Test (*vs BL, **vs Ctrl). During control, SNS significantly reduced ERP and VFT and increased RT slope but only at LV base, (Table). In the presence of HMR1556, the effects of SNS on ERP and VFT were augmented whilst the effect on RT was abolished. In conclusion, SNS increases susceptibility to VF which appears to be augmented in this pharmacological LQTS1 model and related to changes in ERP but not RT.Research support from the University of Leicester
ROLE OF NITRIC OXIDE SYNTHASE AND SERCA ON THROMBOXANE RELEASE IN THE VASCULAR HYPERREACTIVITY INDUCED BY DIABETES MELLITUS
Authors: Morales‐Loredo Humberto , Espinosa‐Tanguma Ricardo 
Published: June 2021

The molecular mechanisms that lead to the diabetes mellitus (DM) vascular hyper‐reactivity still are a matter of debate. Unpublished results from our laboratory showed that aortic rings from streptozotocin (STZ)‐DM induced rats with 10 weeks of evolution have: a) an endothelium‐dependent vascular hyper‐reactivity, b) a similar response to phenylephrine (Phe, 10μM) when incubated with the sarcoendoplasmic reticulum Ca2+ ATPase (SERCA) blocker thapsigargin (Thaps, 1μM) which is also a sarcoendoplasmic reticulum stress inducer, and c) a decreased hyper‐reactivity when incubated with indomethacin or the TXA2 receptor blocker SQ 28548 (1μM). In order to further investigate the mechanism involved in DM induced vascular hyper‐reactivity, in the present work we evaluated: a) the effect of nitric oxide synthase (NOS) blockade with L‐NAME (100 μM) on DM‐induced vascular hyper‐reactivity, b) the SERCA expression in aorta, and c) the thromboxane release from aortic tissue stimulated with: Phe (10 μM), Phe + Thaps (1μM), and L‐NAME (100 μM) + Thaps (1μM) + Phe (10 μM).RESULTSSERCA protein expression was decreased in aortic tissue from DM compared with CTRL. The ELISA assay for TXB2 showed that thromboxane release was increased in: 1) diabetic tissue with vehicle, 2) diabetic tissue stimulated with Phe, and 3) diabetic tissue with L‐NAME + Phe. Both, the tissue from CTRL rats treated with Thaps + Phe or with L‐NAME + Thaps + Phe, released TXB2 at levels comparable to those from DM. Nevertheless, L‐NAME decreased the releasing of TXB2 and the vascular hyper‐reactivity as well.CONCLUSIONSOur results suggest that the decrease in the expression of SERCA pump in DM could increase the cytosolic Ca2+ concentration, which in turn increases the vasoactive agent's release, mainly TXA2. Also, our data suggest that NO is involved in the release of TXA2 which produces vascular hyper‐reactivity.
Psycho‐Physiological Changes in Mouse Strain Submitted to Social Stress
Authors: Jibitu Meskerem 
Published: June 2021

Three different mouse strains of C57BL/6j, BABLB/cj and DBA/2j were submitted to 10 day and 5 day aggressor exposed (Agg‐E) stress. Mice were kept inside an aggressor (Agg ) home cage and randomly exposed to the Agg three times a day for one minute or up to ten attacks while the controls never experiences the Agg. The ethogram of the Agg‐E stress evaluated by a situation reminder study was analyzed immediately post stress and after a pre‐determined rest period.C57BL/6j, BABLB/cj and DBA/2j displayed noticeable changes in behavioral parameters such as jumping, fighting‐back, grooming, tail rattling and freeze motion when exposed to (Agg ) mice for 5‐ or 10‐day. Strain‐wide physiological alteration was evaluated in body weight, body temperature changes and urine marking; a sign of territorial behavior.Situation reminder evaluated a cluster of traits simulating post‐traumatic stress disorder. Three strains responded differently to a contextual stress 1day and 1.5 weeks post 5‐day social stress, and 1 day and 6 weeks post 10 day social stress. Final result indicate, that DBA/2j and BALB/cj is most resilient and vulnerable to Agg‐E stress, respectively. C57BL/6j displayed a modest change in phenotype character primarily after 10‐day stress.Data analyses of psychological and physiological results were calculated using EthoVision and Graph Pad prism software.