bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of urotensin II receptor induces podocyte injury via TRPC6-mediated endoplasmic reticulum stress
Authors: Kanthakumar Praghalathan , Adebiyi Adebowale 
Published: May 2023

Podocytes are essential for the glomerular filtration barrier in the kidney. Podocyte injury can lead to chronic kidney disease (CKD). One of the leading causes of CKD is diabetes mellitus. Plasma urotensin II (UII) levels and renal tissue expression of UII and its receptor UT are increased in diabetic kidney disease. However, the role of the UII system in podocyte derangement is unexplored. In this study, we report for the first time that UT is expressed in mouse podocytes in culture and glomerular explants. UII increased intracellular Ca2+ levels ([Ca2+]i) in cultured podocytes bathed in zero Ca2+ solution, an effect abolished by ER Ca2+ ATPase inhibitor thapsigargin. Subsequent restoration of extracellular Ca2+ increased [Ca2+]i despite the blockade of voltage-gated Ca2+ channels, suggesting a store-operated Ca2+ entry (SOCE) mechanism activated by UII. UII precipitated ER injury in cultured podocytes, as indicated by an increase in ER stress marker GRP78. GSK1562590, a UT antagonist, reversed this effect. Next, we tested two putative SOCE pathways previously reported in podocytes, i.e., TRPC5 and TRPC6 ion channels. Activation of UT by UII significantly increased TRPC6 but not TRPC5 mRNA in cultured podocytes. Whole-cell patch-clamp recordings of cultured podocytes showed that UII stimulates cation currents, which SAR 7443, a selective TRPC6 blocker, attenuated. By contrast, UII-induced cation currents were not sensitive to AC 1903, a selective TRPC5 blocker. In line with patch-clamp experiments, Ca2+ imaging studies showed that TRPC6 blockade with SAR 7443 mitigated UII-induced increase in [Ca2+]i. Super-resolution microscopy of cultured podocytes revealed that activation of UT caused a significant increase in the fragmentation of actin filaments, as indicated by a decrease in the percentage of long filaments and an increase in short filaments. Together these findings suggest that: (1) UT is expressed in native and cultured podocytes. (2) UT activation in podocytes triggers ER Ca2+ release, activates SOCE pathways and leads to the development of ER stress. (3) TRPC6 is a probable SOCE pathway stimulated by UII in podocytes. (4) UII might cause podocyte injury by disrupting the actin cytoskeleton. Dr. Adebiyi: NIH R01 HL151735 and R01 DK127625; APS 2020 John F. Perkins, Jr. Research Career Enhancement Award. Dr. Kanthakumar: American Heart Association Postdoctoral Fellowship (830462). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Estrogen regulates myogenic tone in hippocampal arterioles by enhanced basal release of nitric oxide and endothelial SK channel activity
Authors: Dabertrand Fabrice 
Published: May 2023

Arteries and arterioles exhibit myogenic tone, a partially constricted state that allows further constriction or dilation in response to moment-to-moment fluctuations in blood pressure. The vascular endothelium that lines the internal surface of all blood vessels controls a wide variety of essential functions, including the contractility of the adjacent smooth muscle cells by providing a tonic vasodilatory influence. Studies conducted on large (pial) arteries on the surface of the brain have shown that estrogen lowers myogenic tone in female mice by enhancing nitric oxide (NO) release from the endothelium, however, whether this difference extends to the intracerebral microcirculation remains ambiguous. The existing incomplete picture of sex differences in cerebrovascular physiology combined with a deficiency in treatments that fully restore cognitive function after cerebrovascular accidents places heavy emphasis on the necessity to investigate myogenic tone regulation in the microcirculation from both male and female mice. We hypothesized that sex-linked hormone regulation of myogenic tone extends its influence to the microcirculation level, and sought to characterize it in isolated arterioles from the hippocampus, a major cognitive brain area. Using diameter measurements in pressure myography experiments, we measured lower myogenic tone responses in hippocampal arterioles from female than male mice at physiologically relevant pressures. By using a combined surgical and pharmacological approach, we found myogenic tone in ovarectomized (OVX) female mice matches that of males, as well as in endothelium-denuded arterioles. Interestingly, eNOS inhibition induced a larger constriction in female arterioles but only partially abolished the difference in tone. We identified that the remnant difference was mediated by a higher activity of the small-conductance Ca2+-sensitive K+ (SK) channels. Collectively, these data indicate that eNOS and SK channels exert greater vasodilatory influence over myogenic tone in female mice at physiological pressures. R01HL136636; RF1NS129022 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
DNA methylation inhibitor regulates guanylyl cyclase/natriuretic peptide receptor-A gene expression via 5'-untranslated region in mesangial and smooth muscle cells
Authors: Kumar Prerna , Neerukonda Smitha , Bloodworth Meaghan , N. Peters Whitney , N. Pandey Kailash 
Published: May 2023

Guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) is activated by cardiac hormones atrial and brain natriuretic peptides (ANP, BNP) and produces intracellular second messenger cGMP. The physiological actions of ANP/NPRA/cGMP signaling cascade largely include diuresis, natriuresis, vasorelaxation, and organ protection, which maintains blood pressure and opposed renal, cardiac, and vascular injury and remodeling. However, the mechanisms that contribute to the activation of Npr1 (coding for GC-A/NPRA) expression is not well understood. The present study was aimed at understanding the epigenetic mechanisms of DNA methyltransferase (DNMT) inhibitor, 5-Azacytidine (5-Aza)-mediated Npr1 gene transcription. The studies were carried out in mouse mesangial cells (MMCs) and rat thoracic aortic smooth muscle (RTASM) cells, cultured in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum and ITS (insulin, transferrin, and sodium selenite) and treated with 5-Aza for 24 h. Western blot analysis showed that 5-Aza enhanced NPRA protein levels by 5-fold and 7-fold in a dose-dependent manner in MMCs and RTASM cells, respectively, and greatly stimulated intracellular accumulation of cGMP in ANP-treated cells. Treatment with 5-Aza attenuated DNMT activity and repressed DNMT1 protein levels in cells. The MethPrimer search result showed the presence of three cytosine-phosphate-guanine (CpG) islands in the Npr1 full length promoter and 5'-untranslated region (UTR), namely island 1 (-886 to -752, 134 bp), island 2 (-310 to -158, 152 bp), and island 3 (-154 to +310, 464 bp) from the transcription start site. Addition of 5'-UTR encompassing +56 to +359 bp region to the Npr1 promoter constructs, (-1982/+55) and proximal promoter (-356/+55), was inhibitory to Npr1 transcriptional activity, independent of the cell type. Furthermore, treatment with 5-Aza distinctly induced Npr1 promoter activity of the construct -356/5'-UTR by 10-fold in MMCs suggesting that the repressive effect of DNA methylation on Npr1 gene transcription might be via 5'-UTR. The results demonstrate that 5-Aza acts as a potent inducer of Npr1 expression and signaling and provides new insights in the epigenetic control of Npr1, an important player in the control of hypertension and cardiorenal axis. Supported by the NIH grants (HL062147 and DK133833). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Actin Polymerization Increases in The Ductus Arteriosus During The Developmental Transition to Lung Ventilation
Authors: Werra Hakeem , Dzialowski Edward , Rippamonti Jessica 
Published: May 2023

The Ductus Arteriosus (DA) is an embryonic blood vessel that connects the descending aorta and the pulmonary artery during fetal development. It functions as a right-to-left shunt diverting blood away from the nonventilated lungs and to the descending aorta. The DA serves a comparable physiological role in all terrestrial vertebrates during their embryonic development. Following birth or hatching, the DA constricts in response to increase in arterial oxygen tension brought on by initiation of lung ventilation, and it closes to stop the embryonic shunt. We examined the extent of actin polymerization in the DA during the transition to lung ventilation at hatching in the chicken. We isolated and fixed DA from developing chickens on embryonic days 15 and 19 (ED15 and ED19), during internal pipping (IP) and external pipping (EP), and in hatchlings. Vessel sections were fluorescently stained with Alexa Fluor 488 (DNase 1) for G-actin, Alexa Fluor 568 (Phalloidin) for F-actin, and TOPRO-3 for nuclei staining. Fluorescence microscopy was used to image the sections and quantify F-actin to G-actin levels within the DA for each age. From the images, F-actin to G-actin ratios were determined. Embryonic stages exhibited strong G-actin staining with minimal F-actin staining. During hatching, F-actin staining became more pronounced, exhibiting clearer fiber patterns in the tunica media. F-actin to G-actin ratios increased significantly in the DA from ED15 through hatching, suggesting actin polymerization in the DA increased as the chickens progressed from day 19 to external pipping (EP). These results suggest that increases in actin polymerization play a role in ductus arteriosus constriction at hatching in chickens. This research is funded by grant R15HL14887 from the NIH-NHLBI. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Role of TRPV4 in superficial cervical lymphatic vessel contractile function
Authors: Polk Felipe , Pires Paulo 
Published: May 2023

Collecting cervical lymphatic vessels pump lymph and macromolecules drained by brain meningeal lymphatics to the cervical lymph nodes. Collecting lymphatics vessels rely on spontaneous contractions to propel lymph against a pressure gradient to re-enter the venous circulation. The calcium permeable transient receptor potential vanilloid 4 channel (TRPV4) has been shown to mediate intraluminal pressure-induced vasodilatory responses in small arteries. However, whether TRPV4 participates in pressure-dependent contractile responses in lymphatic vessels remains unclear. We hypothesized that increases in intraluminal pressure leads to TRPV4-dependent increases in lymphatic pump function. TRPV4 expression was assessed by PCR assay in isolated superficial cervical lymphatic vessels (sCLV). Using pressure myography, contractile function of isolated sCLV was assessed in the presence of TRPV4 antagonist (1μM HC-067047) or vehicle (DMSO). To quantify lymphatic pump function (FPF), the product of contractile frequency (FREQ) and ejection fraction (EF) was analyzed using repeated end-diastolic and end-systolic diameter measurements. We detected TRPV4 mRNA expression following PCR amplification from isolated sCLV tissue of young C57Bl/6J mice (4-6 months). In pressurized sCLV, TRPV4 activation with GSK 1016790A (10 nM) abolished spontaneous rhythm contractions by causing a sustained constriction, consequently leading to a significant decrease in lymphatic pump function (FPF: 4.67±0.58 vs 1.17±0.86, Vehicle vs GSK 1016790A, n=8, p<0.05) at baseline intraluminal pressure (3 cm H2O). TRPV4 antagonism (HC-067047, 1 μM) did not affect basal sCLV contractility (FPF: 5.15±0.6 vs 3.44±0.43, Vehicle vs HC 067047, n=5, p>0.05). Further, when HC-067047 was applied to the bath and intraluminal pressure was maintained at 2 cm H2O, no changes were observed in FREQ (9.3±1.4 vs 11.7±1.3 Hz, Vehicle vs. HC-067047, n=7 / 9, p>0.05), EF (0.253±0.040 vs 0.268±0.037, Vehicle vs. HC-067047, n=7 / 9, p>0.05), or contractile amplitude (22.54±6.769 vs 26.76±3.028 μm, Vehicle vs HC-067047, n=7 / 9, p>0.05). Similarly, TRPV4 blockade did not alter FREQ (12.4±1.3 vs 14.3±1.4 Hz, Vehicle vs. HC-067047, n=7 / 9, p>0.05), EF (0.090±0.024 vs 0.092±0.019, Vehicle vs HC-067047) or contractile amplitude (7.98±2.814 vehicle vs 9.27±1.88 μm, Vehicle vs HC-067047) at the higher intraluminal pressure of 7 cm H2O. Collectively, these data suggest that TRPV4 channels are not involved in pressure-dependent contractile responses of sCLV in mice, despite inducing a robust constriction upon pharmacological activation. National Institutes of Health (R01 AG073230) and the Alzheimer's Association (AARGD-21-850835) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Adolescent is more susceptible to tuft cell hyperplasia with increased mast cell infiltration and enhanced FFA2/5-HT mediated anion secretion in mouse duodenum and jejunum
Authors: Ito Suguru , Akiba Yasutada , Kaunitz Jonathan 
Published: May 2023

Though one of the primary functions of intestinal tuft cells us the sensing of the luminal content, the contribution of tuft cells to epithelial secretion has not been previously studied. We have found that in adult mice, induced tuft cell hyperplasia enhances the secretory responses to luminal short-chain fatty acids (SCFA) due to increased jejunal cholinergic signaling, whereas mast cell-mediated serotonergic signaling is predominant in the duodenum. Since mast cell density is higher in children with functional dyspepsia (FD) than in adults, we hypothesized that mast cell density and 5-HT signals may be increased by tuft cell hyperplasia more in adolescent (7-week-old; 7 wk) than in adult mice (15-week-old; 15 wk). Tuft cell hyperplasia was induced by oral sodium succinate (NaSuc, 100 mM) in the drinking water for 7 days in 7 wk or 15 wk mice, then assessed at 8 or 16 wk (8 w/16 w). Using Ussing chambers mounted with muscle-stripped mouse proximal duodenum or jejunum, the succinate receptor agonist cis-epoxy succinic acid (cESA, 1-30 mM) was applied to the mucosal bath whereas the selective free fatty acid receptor 2 (FFA2) agonist 4-CMTB (10 μM) was added to the serosal bath. Tuft cell doublecortin-like kinase 1 (DCLK1), mast cell protease 1 (MCPT1), and tryptophan hydroxylase 1 (TPH1/5-HT), used to measure tuft cell, mast cell, and enterochromaffin (EC) cell density, respectively, were assessed by real-time PCR and immunostaining.NaSuc treatment significantly increased the number of DCLK1-positive tuft cells and MCPT1-positive mast cells with no change in EC cell density in the duodenal and jejunal villi; density was higher at 8 w than at 16 w. mRNA expression of DCLK1 was increased in the duodenal and jejunal mucosa at both ages, whereas MCPT1, TPH1 and FFA2 were increased in both mucosæ at 8 w, but choline acetyltransferase (ChAT) was increased in the jejunal mucosa at 16 w. Luminal cESA increased atropine-inhibitable Isc in the jejunal mucosa, whereas 4-CMTB increased 5-HT3/5-HT4-mediated duodenal Isc. The Isc response to cESA in jejunum was enhanced at 16 w, whereas the response to 4-CMTB was enhanced at 8 w.These results suggest that NaSuc differentially enhances secretory responses, with jejunal serotonergic signals predominating at 8 w and cholinergic signals at 16 w. These data suggest that younger mice are more susceptible to tuft cell hyperplasia with resultant enhanced 5-HT signals with mast cell infiltration, consistent with clinical data. Supported by VA Merit Review This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Crosstalk between hepatic uridine biosynthesis and ER stress in obesity and type 2 diabetes
Authors: Deng Yingfeng , Fu Ling , Kebrom Leah , Jang Chelsea , Kalkum Markus , Scherer Philipp 
Published: May 2023

Pathologically elevated hepatic glucose production is one of the most important etiologies of type 2 diabetes mellitus (T2DM). The underlying molecular mechanism remains ill-defined. Uridine is the most abundant nucleoside in circulation. Blood uridine level is stably maintained in mammals since excess uridine promotes spontaneous tumorigenesis. We recently showed that adipose tissue is a novel site to supply uridine in addition to the liver (Deng Y, et al., Science, 2017). Obesity, a condition with increased fat mass, is therefore associated with a higher supply of uridine from adipose tissue. To maintain homeostatic circulating uridine level in obesity, de novo uridine synthesis in hepatocytes will need to be reduced. Consistent with this notion, we found that Cad, the rate-limiting enzyme for uridine synthesis, is decreased in the liver by HFD feeding. Aspartate (Asp) is a key substrate for hepatic uridine synthesis. Importantly, Asp is also an essential substrate for hepatic glucose production. Therefore, the reduction of uridine biosynthesis in obesity (more Asp is available) may increase hepatic glucose production. Conversely, upregulation of uridine synthesis may suppress glucose output and type 2 diabetes. Based on this rationale, we hypothesize that hepatic uridine synthesis and glucose production are reciprocally regulated and reduced liver uridine synthesis is a main cause for elevated hepatic glucose production in obesity and T2DM. To test this hypothesis, we engineered a mouse model in which Cad is deleted in hepatocytes. Preliminary data showed that liver gluconeogenetic pathway was upregulated by Cad deletion. Consistently, PALA, an inhibitor of uridine synthesis, caused an acute elevation in blood glucose (hyperglycemia), again supporting a role of uridine synthesis in hepatic glycemic control. We further showed that XBP1s, the most conserved branch of ER stress and the UPR (unfolded protein response), is a key regulator of de novo uridine synthesis via upregulation of Cad expression. Hepatocyte overexpression of XBP1s leads to hypoglycemia and lipolysis. Taken together, our study uncovers a novel link of uridine homeostasis and hepatic glycemic control through cellular response to ER stress, which provides potential targets for therapeutic design against obesity and T2D. Supported by the American Diabetes Association and NIDDK. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Comparison of shear-wave elastography to state-of-the-art respiratory function testing to measure the range of forces generated by the diaphragm muscle
Authors: Gransee Heather , Smith Joshua , Johnston Jessica , Knoll Kate , Lee Hyungkyi , Jiang Lai , Urban Matthew , Johnson Bruce , Mantilla Carlos 
Published: May 2023

The diaphragm muscle is important in both sustaining ventilation and performing higher-force behaviors necessary for maintaining airway patency. Ventilatory behaviors (i.e., eupnea and response to hypoxia-hypercapnia) require only ~20% of maximal force generation, whereas coughing requires forces ~60% of maximal. Existing techniques to measure the full range of forces generated by respiratory muscles are limited by their invasiveness (e.g., balloon manometry for transdiaphragmatic pressure (Pdi) measurements), requirements for training, supervision and subjectivity (e.g., maximal inspiratory and expiratory pressures). Ultrasound-based shear-wave elastography (SWE) assesses muscle stiffness and has shown promising results in being used as a surrogate for Pdi to evaluate diaphragm muscle force. Previous literature has demonstrated a correlation between diaphragm SWE and Pdi at lower force behaviors and the goal of the present study was to evaluate the efficacy of SWE-based measurements of the diaphragm in correlating with Pdi measurements across the range of forces generated by the diaphragm. In this pilot study, we recruited 6 male and 5 female healthy volunteers. Subjects were positioned in a seated position with their torso unsupported. Pdi was measured during graded inspiratory threshold loading trials using a POWERbreathe Plus commercial inspiratory loading device, as well as during maximal inspiratory pressure (MIP). Simultaneously, SWE was performed at the zone of apposition in the right anterior axillary line, and diaphragm Young’s modulus and shear wave speed were subsequently measured. The average Pdi during MIP testing was 149 ± 66 cm H2O. Pdi during inspiratory loading at a low resistance was 39 ± 14 cm H2O and at a high resistance was 78 ± 29 cm H2O. Subjects were able to generate an average Pdi range of 39 ± 19 cm H2O across the graded resistance levels, and the average percent of MIP obtained was 54 ± 13%. Average Young’s modulus as measured with SWE during inspiratory loading at a low resistance was 46 ± 19 kPa and at a high resistance was 104 ± 19 kPa. From low to high resistance, Pdi, Young’s modulus, and shear wave speed increased by an average of 100%, 126%, and 59%, respectively. Taken together, SWE is a promising method of non-invasive assessment of diaphragm muscle forces across a range of voluntary behaviors. Support from NIH grant R21 DA055848 and the Mayo Clinic. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.