bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cldn2-Trpv6 double knockout mice have hypocalcaemia and reduced bone mineral density
Authors: Bhullar Harneet , Alexander Todd 
Published: May 2023

Central to calcium homeostasis and bone health is adequate intestinal calcium absorption. This occurs via either a transcellular or a paracellular pathway. In cases of low dietary calcium availability, a transcellular pathway that relies at least in part on the apical calcium channel Trpv6 predominates. However, when calcium is abundant in the diet, paracellular calcium absorption occurs through tight junction proteins, including claudin-2 (Cldn2). This tight junction protein also plays a role in calcium reabsorption from the renal proximal tubule. Despite this, Cldn2 knockout mice only display mildly altered calcium homeostasis characterized by hypercalciuria without evidence of altered bone mineral density (BMD), plasma calcium or calciotropic hormone levels. Similarly, mice expressing non-functional mutant Trpv6 (TRPV6D541A/D541A) channels have reduced intestinal calcium absorption without altered urine or plasma calcium levels, and only when fed a low calcium diet. We hypothesized that the lack of a more pronounced phenotype in these single functional knockout mice was due to the compensation of one pathway in the absence of the other. To test this hypothesis, we crossed claudin-2 knockout mice with mice expressing the mutant Trpv6, generating a functional double knockout (dko, Trpv6mut/mut/Cldn2-/- mice). Metabolic cage studies revealed hypocalcaemia (Male WT: 1.07 ± 0.02 mM, Male DKO: 0.97 ± 0.02 mM, p-value=0.0065, Female WT: 1.07 ± 0.02 mM, Female dko: 0.96 ± 0.03 mM , p-value= 0.0050) and hypercalciuria (Male WT Ca2+/Creatinine: 0.51 ± 0.05, Male dko:1.93 ± 0.18, p-value < 0.0001 Female WT Ca2+/Creatinine: 1.10 ± 0.13, Female dko: 3.56 ± 0.28 , p-value < 0.0001) in the dko mice. In contrast to the single claudin-2 KO mice and Trpv6 mutant animals the dko mice had elevated plasma calcitriol and parathyroid hormone. Moreover, BMD was reduced in the dko animals (Cortical BMD WT: 1.36 ± 0.02 g/cm3 vs dko: 1.29 ± 0.02g/cm3 ). RT-qPCR of intestinal segments and whole kidney revealed increased calbindin-D9k expression in the proximal colon (but not duodenum) and calbindin-D28k in the kidneys, consistent with compensatory increased transcellular absorption from these intestinal segments. Together these results are consistent with the paracellular pathway compensating for the loss of transcellular calcium absorption from the intestine. Funding: Alberta Innovates Graduate Studentship, NSERC, CIHR 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.
Effects of acute intermittent hypoxia on P0.1 in humans with spinal cord injury
Authors: Mir Michela , Vose Alicia , Brunetti Gina , Cavka Kathryn , DeMark Louis , Snyder Hannah , Wauneka Clayton , Welch Joseph , Nair Jayakrishnan , Mitchell Gordon , Fox Emily 
Published: May 2023

Spinal cord injury (SCI) disrupts neural pathways to respiratory motor neurons, diminishing respiratory drive and breathing function. Breathing impairment remains a leading cause of illness and death after SCI. Therapeutic acute intermittent hypoxia (tAIH; 15, 1-minute episodes of 9% inspired O2, 1.5 min normoxic intervals), a promising strategy to restore breathing function after SCI, promotes spinal neuroplasticity in rodent models. However, in humans, respiratory drive is unchanged after a single tAIH session; thus we tested the hypothesis that tAIH on five successive days increases neuromechanical respiratory drive in humans living with chronic SCI. Sixteen participants with chronic SCI (1 female; 33.5 + 15.3 years of age; 1-28 years post-SCI; 11 cervical, 5 thoracic; C1-T6 AIS A-D) were studied; their respiratory function was 52% ± 19% of age predicted expiratory pressure generation, and 123% ± 32% for inspiratory pressure. Five days of tAIH or Sham treatment were delivered in a randomized, cross-over design (minimum 3 weeks apart). Airway occlusion pressure in the first 0.1s of inspiration (P0.1), a surrogate for neuromechanical respiratory drive prior to within-breath sensory feedback, was collected at baseline and at 1, 3, and 7-days post-treatment. Repeated measures ANOVA revealed no significant effect of time (F(3)=.49; P=.69) or group (F(3)=1.33; P=.27). Despite the lack of significant differences in this preliminary analysis, P0.1 increased by 25% on day 3 versus 0.8% after Sham. Because of this change, pairwise comparisons were conducted, revealing a near significant increase in P0.1, 3 days post tAIH (MD=-.17; P =.06). Thus, although P0.1, a surrogate for neuromechanical respiratory drive, did not significantly increase after 5 days of AIH in people with SCI, the marginally significant change at day 3 suggests further investigation is warranted. Next steps include assessment in a larger sample, investigation of biomarkers for treatment effects, and examination of combinatorial interventions including task specific training and/or mild CO2 elevations to enhance AIH-induced neuroplasticity in the drive to breathe. DoD SCIRP Clinical Trial Award W81XWH-17-SCIRP-CTA; The Craig H. Neilsen Foundation (JW); NIH T32 HL134621 (MM); and the UF McKnight Brain Institute. 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.
The role of short-chain fatty acid receptors in the hypothalamic paraventricular nucleus of adult offspring in hypertension programmed by maternal high fructose diet exposure
Authors: Chan Julie Y.H. 
Published: May 2023

The role of short-chain fatty acids (SCFAs) in the brain on developmental programming of hypertension is poorly understood. The present study aimed to explore the dysregulated tissue levels of SCFAs and expression of SCFA-sensing receptors in the hypothalamic paraventricular nucleus (PVN), a key forebrain region engaged in neural regulation of blood pressure, of offspring to maternal high fructose diet (HFD) exposure. We further investigated the engagement of SCFA-sensing receptors in the PVN on the beneficial effects of -biotics (prebiotic, probiotic, synbiotic and postbiotic) on programmed hypertension primed by maternal HFD. Maternal HFD during gestation and lactation significantly reduced circulating butyrate, along with decreased tissue level of butyrate and increased expression of the SCFA-sensing receptors, GPR41 and olfr78, in the PVN of HFD offspring that could be rectified by oral supplement with prebiotic, probiotic, or synbiotic. The maternal HFD-primed programmed hypertension in adult offspring was accompanied by tissue oxidative stress and neuroinflammation in the PVN, both of which were reversed by oral supplement with the -biotics. Gene silencing of GPR41 or olfr78 mRNA in the PVN also protected adult HFD offspring from programmed hypertension and alleviated the induced oxidative stress and inflammation in the PVN. In addition, oral supplement with the postbiotic butyrate notably restored tissue butyrate level and rectified the expressions of GPR41 and olfr78 in the PVN of HFD offspring. The same treatment also protected against programmed hypertension in adult HFD offspring. These data together suggest that alterations in tissue butyrate level and expression of the SCFA-sensing receptors of GPR41 and olfr78, as well as activation of the SCFA-sensing receptor-dependent tissue oxidative stress and neuroinflammation in the PVN could be novel mechanisms that underlie hypertension programmed by maternal HFD exposure in adult offspring. Furthermore, oral -biotics supplementation may exert beneficial effects on hypertension of developmental origin by targeting the dysfunctional SCFA-sensing receptors in the PVN to exert antioxidant and anti-inflammatory actions in the brain. This research was funded in part by the Chang Gung Medical Foundation, Taiwan (grant number: OMRPG8G0011), and the Ministry of Science and Technology, Taiwan (grant number: MOST111-2320-B-182A-015). 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.
Mitochondrial integrity distinguishes exercise-induced vs. pathogenic cardiac hypertrophy
Authors: Yang Nicole Lee , Strumwasser Alexander , Zhou Zhenqi , Moore Timothy , Hevener Andrea 
Published: May 2023

Cardiac hypertrophy is a consequence of exercise training, as well as certain cardiomyopathies. However, the key genetic drivers of cardiac remodeling in a healthy vs diseased heart are inadequately understood. Our purpose was to determine the genetic architecture of exercise training-induced cardiac remodeling and hypertrophy. The exercise hybrid mouse diversity panel (ExcHMDP) is comprised of 100 strains of Exc trained (TRN) and sedentary (SED) animals (n=4-8/strain/group). After 30d of exercise, running wheels were locked, and 24-hours post-exercise, 6h-fasted animals were euthanized and tissues harvested (~20 tissues/mouse). To interrogate pathogenic cardiac hypertrophy, isoproterenol (ISO, 30mg/kg/day for 21d) was administered to a second HMDP cohort, and similar to TRN hearts, RNAseq analyses were performed. TRN increased heart weight in 85 of 100 mouse strains vs. SED. Of the nearly thirty heart phenotypes assessed, none correlated significantly with running distance. Enrichment analysis of differential gene expression revealed mitochondrial function, inflammatory and immune processes, calcium signaling, muscle growth and development, and angiogenesis (FDR<0.05) as top pathways impacted by TRN. Biological processes divergent between the Exc and ISO-HMDPs included oxidative phosphorylation, electron transport chain, and mitochondrial respiratory chain complex assembly (FDR<1.1E-07). Electron microscopy analyses of TRN vs. ISO hearts showed differential remodeling of mitochondrial cristae involved in oxidative metabolism. Preliminary sex differences studies using an acute cardiac Esr1 (estrogen receptor alpha, ERa) knockout revealed reduced cardiac function, impaired mitochondrial metabolism, and extensive myocardial fibrosis in adult female C56Bl6/J mice (n=6); molecular assays revealed increased expression of alpha smooth muscle actin (P=0.002) and collagens Col1a2 and Col6a3 (P=0.02; P=0.006), suggesting that ERa may be a mediator of sex-specific cardiac remodeling. Our studies provide important insight into the genetic architecture of cardiac remodeling associated with healthy vs. pathogenic hypertrophy. A primary goal is that our transcriptomics analyses are leveraged to advance therapeutics to combat hypertrophic cardiac myopathy-associated heart failure. Funding: NIH U01 AG070959; U54DK120342 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.
FOXO1 cooperates with C/EBPΔ and ATF4 to regulate skeletal muscle atrophy transcriptional program during fasting
Authors: Kamei Yasutomi , Oyabu Mamoru 
Published: May 2023

Catabolic conditions, such as starvation, inactivity, and cancer cachexia, induce Forkhead box O (FOXO) transcription factor(s) expression and severe muscle atrophy via the induction of ubiquitin–proteasome system-mediated muscle proteolysis, resulting in frailty and poor quality of life. Although FOXOs are clearly essential for the induction of muscle atrophy, it is unclear whether there are other factors involved in the FOXO-mediated transcriptional regulation. As such, we identified FOXO–CCAAT/enhancer binding protein Δ (C/EBPΔ) signaling pathway as a novel proteolytic pathway. By comparing the gene expression profiles of FOXO1-transgenic (gain-of-function model) and FOXO1,3a,4–/–(loss-of-function model) mice, we identified several novel FOXO1-target genes in skeletal muscle including Redd1, Sestrin1, Castor2, Chac1, Depp1, Lat3, as well as C/EBPΔ. During starvation, C/EBPΔ abundance was increased in a FOXOs-dependent manner. Notably, knockdown of C/EBPΔ prevented the induction of the ubiquitin–proteasome system and decrease of myofibers in FOXO1-activated myotubes. Conversely, C/EBPΔ overexpression in primary myotubes induced myotube atrophy. Furthermore, we demonstrated that FOXO1 enhances the promoter activity of target genes in cooperation with C/EBPΔ and ATF4. This research comprehensively identifies novel FOXO1 target genes in skeletal muscle and clarifies the pathophysiological role of FOXO1, a master regulator of skeletal muscle atrophy. 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.
Identification of protein machineries involved in aquaporin-2 gene transcription with genomic locus proteomics (GLoPro)
Authors: Lin Yi-Jiun , Yeh Ai-Hsin , Chen Hsuan-I , Liu Chin-Fu , Yu Ming-Jiun 
Published: May 2023

Vasopressin-induced water reabsorption by the renal collecting ducts is in part regulated by aquaporin-2 gene expression; however, the mechanism is not completely understood. We used genomic locus proteomics (GLoPro) to identify transcription protein network in the aquaporin-2 5’-flanking region in the mpkCCD cell model. Our strategy relied on a recombinant protein consisted of catalytic dead Cas9 and biotin ligase TurboID (dCas9-TurboID). When guided to -95 bp upstream to the aquaporin-2 transcription start site, it did not affect vasopressin analog dDAVP-induced aquaporin-2 gene transcription. The dCas9-TurboID was used to biotinylate proteins recruited by dDAVP to the above genomic region before affinity-purification followed by label-free identification and quantification with LC-MS/MS. In three independent experiments, 1,647 and 1,676 proteins were identified respectively in the vehicle and dDAVP-treated cells. Bioinformatics analysis showed enriched cellular component GO terms: nucleus, nucleoplasm, and nucleolus, consistent with functions of these identified proteins in gene regulation. Statistical analysis showed up-regulation of 310 proteins and down-regulation of 254 proteins in response to dDAVP. Biological process GO term analysis showed enrichment for mRNA processing, RNA splicing, and chromatin organization. In the dDAVP-upregulated group, we identified proteins involved in chromatin remodeling and histone modification that adjust chromatin accessibility: Baz2b, Npm3, Cbx8, Cdk17, Meaf6, and Prmt1. We also identified transcription factors and cofactors: Paxbp1, Rbm14, Cxxc1, Rbpms, Ccar1, Chch2, and JunB. Of these, JunB has been implicated in aquaporin-2 gene transcription. Based on prior omics data, we used Bayes’ theorem to rank these proteins for possibility in aquaporin-2 gene transcription. The top candidate was Ccar1, which is known to complex with β-catenin and T cell factor to enhance target gene transcription. Vasopressin induces β-catenin nuclear translocation; T cell factor has a conserved binding element in the aquaporin-2 5’-flanking region. Further study is needed to examine the possibility that Ccar1 involves β-catenin and T cell factor to regulate aquaporin-2 transcription. This research was supported by National Science and Technology Concil, R.O.C. (MOST111-2320-B-002-084-MY3). 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.
Cardiovascular and respiratory profile of adenosine A 2A receptors knockout mice submitted to sustained hypoxia
Authors: Reis Souza Juliana , Honório Machado Benedito 
Published: May 2023

Taking into consideration the relevance of adenosine as a signaling molecule during hypoxic challenges and the evidence of an important role of A2A receptors regions of the brainstem involved with the generation and modulation of the autonomic and respiratory functions, in the present study we evaluated the cardiovascular and respiratory changes in response to sustained hypoxia (SH) in knockout mice for A2A receptors (A2AKO). For this, we used male A2AKO and male Balb/c wild-type (WT) mice as a control. Under anesthesia, catheters were inserted into the femoral artery, for recording arterial pressure (MAP), and jugular vein for drug injection. Four days after, mice were submitted to normoxia or SH (24h, FiO2 0.1). At the end of these protocols, cardiovascular and respiratory parameters were recorded. Peripheral chemoreflex was activated by potassium cyanide (KCN, 0,16 mg/Kg, iv). In distinct groups of A2AKO and WT mice, with the femoral artery previously catheterized, respiratory parameters were evaluated before and after SH using whole-body plethysmography. At the end of respiratory recordings, a sample of arterial blood was collected for arterial blood gases analysis. Similar and ignificant reductions in MAP and heart rate (HR) were observed in WT [(102±5 vs 109±6 mmHg, P=0.0172), (329±31 vs 441±55 bpm, P<0.0001)] and A2AKO [(104±5 vs 111±7 mmHg; P=0.0141), (318±59 vs 408±64 bpm, P=0.0006)] mice submitted to SH when compared to their respective normoxia controls (WT: n=11; A2AKO: n=13). Mice from control and A2AKO groups presented similar cardiovascular responses to KCN in normoxic as well as in hypoxic conditions. Under normoxic conditions, A2AKO mice (n=11) presented significant increase in respiratory frequency (241 ± 25 vs 184 ± 11 breaths.min-1, P < 0.0001) when compared to respective genetic controls (n=8). Both A2AKO [(24±3 vs 32± 2 mmHg; P<0.0001), (105±6 vs 90±4 mmHg, P = 0.0002)] and WT [(23±4 vs 32±3 mmHg, P<0.0001), (100±9 vs 88±10 mmHg, P=0.0034)] mice presented a significant reduction in pCO2 and an increase in pO2 after SH. The data are showing that the lack of adenosine A2A receptors does not affect the autonomic responses to chemoreflex activation, but are relevant in modulating respiratory activity in normal mice since in the A2AKO mice it was observed a significant increase in respiratory frequency. The data also suggest that A2A receptors play no major role in autonomic and respiratory changes in mice submitted to SH. FAPESP (2018/15957-2 and 2021/01767-0) and CNPQ (309338/2020-4). 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.
TUDCA treatment restores early protein-restriction-induced aortic hipocontractility and endothelial dysfunction
Authors: Freitas Israelle , Junior Joel , Victorio Jamaira , Carneiro Everardo , Davel Ana Paula 
Published: May 2023

TUDCA treatment restores early protein-restriction-induced aortic hipocontractility and endothelial dysfunction Israelle Netto Freitas1,2; Joel da Silva Junior2; Jamaira Aparecida Victorio1,2; Everardo Magalhães Carneiro1,2; Ana Paula Davel1 1Laboratory of Vascular Biology and 2Obesity and Comorbidities Center-OCRC, Institute of Biology, University of Campinas-UNICAMP, Campinas, SP, Brazil. Malnutrition is a risk factor for the development of vascular dysfunction. Tauroursodeoxycholic acid (TUDCA) inhibits endoplasmic reticulum stress (ERS) and has been demonstrated to be protective against vascular dysfunction in cardiometabolic diseases. Therefore, we hypothesized that TUDCA could be beneficial for endothelial function and vascular contractility during malnutrition. For this, post-weaning male and female mice fed a normoprotein (NP, 14% protein) or low protein (LP, 6% protein, isocaloric) diet for 15 weeks. In the last 2 weeks, some NP and LP animals received TUDCA (300 mg/kg/day, ip) or vehicle. At the end of the treatment, body weight (BW) and systolic blood pressure (SBP) were evaluated and thoracic aortic isolated to assess vascular responses, fluorescence to dihydroethidium (DHE) and gene expression. As results, BW was reduced and SBP was elevated in male and female protein-restricted groups; TUDCA treatment restored SBP but not BW. Only in males, protein restriction impaired endothelium-dependent relaxation to acetylcholine and reduced contractility (phenylephrine, serotonin, and TXA2 analogue U46619) in aorta. TUDCA reversed both endothelial dysfunction and hypocontractility in LP male group. We found reduced expression of smooth muscle 22α (SM22α), α-actin and L-type calcium channel (Cav1.2) in aorta from male LP compared to NP, which was restored by TUDCA treatment. In addition, aorta from male LP group showed increased DHE fluorescence and gene expression of the ERS markers GRP78, ATF6, PERK, IRE1α and CHOP. These alterations were reversed by TUDCA. In conclusion, our data suggest that post-weaning protein restriction results in endothelial dysfunction and aortic hypocontractility in males only. These alterations were associated with oxidative stress and reduced expression of vascular contractile and ERS markers. TUDCA treatment rescued vascular contraction and endothelial function in early protein-restricted mice evidencing the therapeutic potential of this bile acid for the vascular complications associated with undernutrition. The authors have nothing to disclose. Funding source: São Paulo Research Foundation (FAPESP). 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.