bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salt Inducible Kinase (SIK): A potential intracellular signal involved in DOCA‐salt induced hypertension?
Authors: Gonsalez Sabrina Ribeiro , Ferrão Fernanda Magalhães , Gomes Dayane Santos , de Lima Dayvid Goncalves Bezerra , Lowe Jennifer , Prieto Minolfa C , Lara Lucienne S 
Published: November 2023

Sodium sensitizes the cardiovascular‐renal axis resulting in salt‐sensitive hypertension, renal injury, and inappropriate activation of the renin‐angiotensin system (RAS). However, the molecular mechanisms and influences of sodium on blood pressure (BP) remain unclear. In the present study, we aimed to determine the unique effects of Na+ on renal function and the intracellular signaling involved in a rat model of DOCA‐salt induced hypertension. Adult Wistar male rats were subjected to left uninephrectomy, followed by SC administration of deoxycorticosterone acetate (DOCA; 8 mg/kg) or vehicle (mineral oil) and either normal or high salt diet (HS, 4% NaCl) in four groups, as follows: CTRL, CTRL/Salt, DOCA and DOCA/Salt (n=15, each group). CTRL and CTRL/Salt rats exhibited normal systolic BP. In CTRL/Salt rats, GFR was normal, despite BUN and proteinuria. Both, Na+ filtration and excretion loads increased from 0.23 ± 0.0074 in CTRL to 0.30 ± 0.011 (mEq) in CTRL/Salt and from 6.6 × 10−4 ± 1.5 × 10−4 in CTRL to 0.0095 ± 1.5 × 10−4 (mEq) in CTRL/Salt, (P<0.05), respectively. In addition, FENa increased 10 times, as Na+ reabsorption load (mEq) from 0.22 ± 0.064 in CTRL to 0.29 ± 0.011 in CTRL/Salt rats. Na+ reabsorption was increased two‐fold and in parallel with the Na,K‐ATPase activity in the renal cortex. In the hypertensive DOCA rats, these functions were preserved. DOCA/Salt rats showed exacerbated hypertension, increased FENa to a similar extent than CTRL/Salt rats along with augmentation of BUN, and proteinuria. In these rats, the high salt intake lead to 45% reduction in Na,K‐ATPase activity in renal cortex. The histological analyses revealed the presence of renal inflammation in DOCA and DOCA/Salt rats. High‐salt diet and DOCA increased sodium‐inducible kinase (SIK) immunoexpression in the glomeruli. These data suggest that in the absence of high BP, sodium contributes to increase Na,K‐ATPase activity and kidney injury without glomerular function alterations. However, in the DOCA/Salt rat model with established hypertension, increases in sodium excretion include alterations in Na,K‐ATPase activity and SIK, which are potential molecular intracellular signal involved in DOCA‐salt induced hypertension.Support or Funding InformationCNPq (420584/2013‐7 Science Without Borders grant, Government of Brazil)and NIH‐NIDDK (RO1DK104375)
Effect of low‐dose of multi‐glycoside of Tripterygium wilfordii Hook. f. on renal injury in mice with salt‐sensitive hypertension
Authors: Wang Youping , Song Chundong , Zhu Mingjun , Xu Hui , Wang Xiaoxiao , Cui Lin , Liu Suxiao , Xie Shiyang , Shen Si , Zhang Songjiang , Wang Donna H 
Published: November 2023

To clarify the effects of low‐dose of multi‐glycoside of Tripterygium wilfordii Hook. F. (GTW), an extract from a Chinese herb thunder god vine, on salt‐sensitive hypertension‐induced renal damage, we induced hypertension by uninephrectomy and deoxycorticosterone (DOCA)‐salt in mice with or without low‐dose of GTW treatment. DOCA‐salt treatment for 5 weeks increased mean arterial pressure (MAP) (P<0.01) and urinary albumin excretion (P<0.05), and also induced renal hypertrophy (P<0.01) compared with the control. Periodic acid‐Schiff and Masson's trichrome staining showed that DOCA‐salt treatment caused obvious glomerulosclrosis and tubulointerstitial injury in the renal cortex (P<0.05), and tubulointerstitial fibrosis compared with the control mice. Consistent with the results, renal collagen level determined using hydroxyproline assay was higher in DOCA‐salt‐treated mice compared with the control mice (P<0.05). Treatment with GTW at the low dose of 11.5 mg/kg/day by gavage had no effect on MAP and renal hypertrophy. However, it partially prevented renal morphological damage and reduced the increases in urinary albumin excretion and renal collagen (P<0.05). Our data showed that treatment with the low dose of GTW prevented renal damage induced by DOCA‐salt hypertension independently of their effects on blood pressure. The results indicate that low‐dose of GTW exhibits a protective effect on renal damage during salt‐sensitive hypertension. This work was supported in part by the National Natural Science Foundation of China (No. 81170243).Support or Funding InformationNational Natural Science Foundation of China (No. 81170243)
Zinc Deficiency Stimulates Sodium Chloride Cotransporter (NCC) Upregulation via Modulation of Calcineurin Activity in Mouse Distal Convoluted Tubular Cells
Authors: Williams Clintoria R. , Mistry Monisha , Li Mirandy S. , Ko Benjamin , Gooch Jennifer L. , Hoover Robert S. 
Published: November 2023

BackgroundZn2+ deficiency (ZnD) has been implicated in the development of hypertension. However, the mechanisms continue to be defined. The Sodium Chloride Cotransporter (NCC) plays a critical role in Na+ handling by the distal convoluted tubule and subsequent blood pressure homeostasis. Furthermore, experimental studies support a direct role for the Zn2+‐dependent enzyme calcineurin in NCC regulation.HypothesisThe objective of this study is to investigate the effects of ZnD on NCC. We hypothesize that Zn2+ regulates NCC via modulation of calcineurin activity.MethodsTo test this hypothesis, mouse distal convoluted tubular (mDCT) cells were exposed to the Zn2+ chelator N,N,N′,N′‐Tetrakis(2‐pyridylmethyl)ethylenediamine (TPEN) or vehicle (DMSO) for 24 hours. To investigate the role of calcineurin in NCC regulation, mDCT cells were treated with the calcineurin inhibitor tacrolimus for 24 hours. NCC expression (qRT‐PCR, Western blot and immunocytochemistry) and activity (thiazide‐sensitive Na+ uptake) were examined as well as calcineurin activity (phosphatase assay).ResultsThe data show that NCC expression is upregulated in mDCT cells following intracellular Zn2+‐depletion with TPEN compared to vehicle‐treated cells. Additionally, calcineurin phosphatase activity is blocked in Zn2+ depleted mDCT cells. Consistent with TPEN findings, inhibition of calcineurin with tacrolimus stimulates NCC expression and activity.ConclusionsTaken together, data suggest that ZnD induces NCC upregulation by inhibiting calcineurin activity.SignificanceThese novel findings identify NCC as a possible mediator of ZnD‐induced hypertension. Understanding the mechanisms by which ZnD contributes to blood pressure dysregulation may have an important impact on the treatment of hypertension.Support or Funding InformationT32‐DK00756 (CRW), R25‐DK101390 (MSL), K08‐DK081728 (BK), VA‐MERIT (JLG), R01‐DK085097 (RSH)
Meprin β deficiency reduces leukocytes infiltration in mouse kidneys with unilateral ureteral obstruction (UUO)‐induced inflammation
Authors: Fernander Mizpha Courtney , Niyitegeka Jean‐Marie Vianney , Conklin Dawn , Yahaya Ismaila , Minor Radiah C , Ongeri Elimelda Moige 
Published: November 2023

Meprins are metalloproteases that are most abundantly expressed in the proximal kidney tubules. Meprins are also expressed in leukocytes (monocytes, and macrophages) suggesting a role in the immune response. Meprins were previously shown to play a role in the movement of leukocytes to sites of inflammation in the small intestines. Furthermore, meprins have been shown to cleave pro‐inflammatory cytokines such as interleukin 1 β (IL‐1β), interleukin 6 (IL‐6), and pro‐interleukin 18 (IL‐18). Proteolytic processing by meprins inactivates IL‐6, but activates IL‐1β and pro IL‐18. The objective of the current study was to determine how meprin β deficiency impacts renal leukocyte infiltration in a unilateral ureteral obstruction (UUO)‐induced inflammation mouse model. Surgical procedures were used to ligate one ureter in 12 week‐old wild‐type (WT) and meprin β knockout male mice. The contralateral kidney served as a control for each mouse. The mice were sacrificed at 7 days post UUO. The kidneys were perfused with saline, subjected to collagenase digestion, and flow cytometry was used to determine the number of leukocytes [T‐cells (CD3+), macrophages (CD11b), and neutophils (LY6G+)] present in kidney tissues. Compared to wild‐type counterparts, we observed a significant decrease (P ≤ 0.05) in Ly6G+ and CD3+ cells in meprin β KO kidneys subjected to UUO. The data suggests that meprin β enhances leukocyte infiltration in the mouse kidneys subjected to UUO‐induced inflammation. Proteomic analysis will determine how the presence of meprins impacts the levels and/or fragmentation of pro‐inflammatory cytokines.Support or Funding InformationNIH/NIGMS SC3GM102049
RORγt‐Dependent Preferential Induction of IL‐17F by TLR3 Activation in SHR Immune Cells
Authors: Singh Madhu V , Cicha Michael Z , Chapleau Mark W , Abboud François M 
Published: November 2023

We have shown that spontaneously hypertensive rats (SHR) have an abnormally large population of CD161+ immune cells at birth that increases further with age compared with age matched normotensive Wistar Kyoto rats (WKY). We also found in SHR spleens a greater abundance of CD161+CD4+ cells that expressed IL‐17A and IL‐17F cytokines known to be synthesized predominantly by T helper 17 (Th17) lymphocytes that are prohypertensive and anti‐T regulatory cells. Here we further define the phenotype of the proinflammatory Th17 in SHR vs. WKY. When subjected to in vitro programming by T cells receptor activation in the presence of IL‐6 and TGF‐β, SHR splenocytes showed significantly greater induction of IL‐17F than WKY (1.4 fold in WKY vs 4.7 fold in SHR, p< 0.05). In contrast activation of the TLR3/TRIF‐mediated pathway with the TLR3 agonist poly‐IC resulted in a preferentially much greater expression of IL‐17F in SHR (2.9 fold in WKY vs. 27 fold in SHR) compared to the modest increase in IL‐I7A in both WKY and SHR (1.7 fold in WKY vs. 2.2 fold in SHR). We also found that this enhanced IL‐17F expression in SHR is dependent on a master regulator transcription factor (the orphan receptor RORγt) which polarizes immune cells into IL‐17 producing Th17 cells. RORγt RNA expression was significantly greater in SHR than in WKY splenocytes (5.7 fold more RORgt in SHR). Using flow cytometry, we confirmed the greater expression of RORγt in CD4+CD161+ cells of SHR. Furthermore, the pronounced induction of IL‐17F by TLR3 activation was suppressed by digoxin (5μM), a specific inhibitor of RORγt. We conclude that SHR has an abnormally large population of CD4+CD161+ Th17 cells with a markedly enhanced potential for expression of proinflammatory, prohypertensive IL‐17F in response to TLR3 activation, driven by the master regulator transcription factor orphan receptor RORγt.Support or Funding InformationNational Institutes of Health Program Project Grant to FMA (HL 14388)VA Merit Review Award to MWC (1 I01 BX001414).
The cGMP/PKG Signaling Pathway Underlies the Inhibitory Effect of Sildenafil Citrate on NHE3 Activity in Rat Renal Proximal Tubules
Authors: dos Santos Priscilla Marys Costa , Pessoa Thaissa Dantas , Malnic Gerhard 
Published: November 2023

Sildenafil (Sil) increases cGMP and inhibits RhoA, and this intracellular pathway has pronounced effects on NHE3 activity. The aim of this work was to determine the effects of Sildenafil on NHE3 and to study the intracellular signaling pathway involved. The studies were performed by the stationary microperfusion technique, in which we measured H+ secretion in rat renal proximal tubules (PT), through a H+‐sensitive microelectrode. PT of Wistar rats (WR) were perfused with 24mM HCO3− (CTRL) +/− 10μM Sil to determine bicarbonate reabsorption (JHCO3−). Luminal perfusion of Sil decreased JHCO3− by 20% compared to CTRL. To test if this effect was NHE3‐dependent, PT were perfused with CTRL, Sil plus 5μM S3226, a specific NHE3 inhibitor, which decreased JHCO3−(39,14% in CTRL and 45,41% in Sil perfused tubules). The remaining S3226‐insensitive JHCO3− was not different among groups, showing that only NHE3 was modulated by Sil. To determine if RhoA was involved in these effects, the PT were perfused with the Rho GTPase inhibitor Y‐27632 (1μM). Perfusion of Y‐27632 alone decreased JHCO3− by 20% compared to CTRL. The perfusion with Y‐27632 increased the inhibitory effect of Sil by 26.16%, suggesting that this effect on JHCO3− was additive and that the inhibitory effect of Sil was caused by another intracellular pathway. Moreover, the inhibitory effect of Sil was completely abolished by the protein kinase G (PKG) inhibitor KT5823 (1μM). These data showed that the inhibitory effect of Sil on NHE3 transport activity in proximal tubule is mediated by activation of cGMP/PKG and that this effect is RhoA independent.Support or Funding InformationFAPESP; CNPq; CAPES
AMPK Stimulates Osmotic Water Permeability in Rat IMCDs
Authors: Wang Yanhua , Efe Orhan , LaRocque Lauren M. , Klein Janet D. , Sands Jeff M. 
Published: November 2023

Our previous studies showed that adenosine monophosphate activated kinase (AMPK) is a possible alternate, vasopressin‐independent, regulatory pathway for urea and water transport. Mice lacking a vasopressin receptor (V2R‐KO) are polyuric. Intraperitoneal (IP) injection of metformin to stimulate AMPK significantly increased urine osmolality from 196 ± 32 (control) to 399 ± 52 mOsM at 1h, and 586 ± 41 mOsM at 5h post treatment in the V2R‐KO mice. Using isolated perfused rat inner medullary collecting ducts (IMCDs), we showed that metformin and AICAR, two AMPK activators, significantly increased urea permeability (control:metformin 16 ± 2 to 22 ± 4 ×10−5 cm/s; control:AICAR 19 ± 2 to 23 ± 3 ×10−5 cm/s). In this study, we investigated the role of AMPK in the regulation of water transport in IMCDs. In perfused rat IMCDs, metformin (400 μM) significantly increased osmotic water permeability from 72 ± 42 to 104 ± 61 μm/s. Immunohistochemistry showed that injecting rats IP with metformin increased the membrane accumulation of total aquaporin‐2 (AQP2) and Serine 256 phosphorylated AQP2 (pSer256‐AQP2). Phosphorylation of Serine 256 is required for AQP2 membrane accumulation. In contrast, western blot analysis of biotinylated proteins showed that metformin did not increase urea transporter UT‐A1 membrane accumulation. We conclude that AMPK activation increases: 1) water permeability by increasing the membrane accumulation of total and pSer256‐AQP2; and 2) urea permeability by stimulating the UT‐A1 transporter that is already present in the membrane. These data show that AMPK activation increases water and urea permeability in rat IMCDs. Thus, activation of AMPK may be a novel therapeutic approach to treating nephrogenic diabetes insipidus due to defective vasopressin signaling.Support or Funding InformationNIDDK
Impaired Urinary Concentration in Car2 Deficient Mice
Authors: Alexander R. Todd , Krishnan Devishree , Cordat Emmanuelle 
Published: November 2023

Pharmacological inhibition of carbonic anhydrases and deficiency of carbonic anhydrase II (Car2) in mice cause polyuria. We therefore set out to determine in Car2 deficient mice by which mechanism(s) polyuria is mediated. Blood gas analysis revealed that Car2 deficient mice have a respiratory acidosis, as reported previously. Moreover, the acidotic mice failed to excrete an acidic urine and had significant bicarbonaturia, consistent with a type III renal tubular acidosis. Carbonic anhydrase inhibitors induce a natriuresis, however Car2 deficient mice did not have altered urinary sodium excretion (either total excretion or FENa). Deletion of NHE3 in mice results in calciuria, and inhibition of NHE3 in cell culture reduces transepithelial calcium flux. Carbonic anhydrase II enhances NHE3 activity and calciuria induces polyuria. However, Car2 deficient mice do not demonstrate altered urinary calcium excretion. Further examination revealed a dilute urine in Car2 deficient mice. Urinary concentration remained reduced in Car2 deficient mice relative to wild‐type animals even after water deprivation. Expression of aquaporin‐2 was not different between genotypes, however Car2‐deficient mice had increased renal aquaporin‐1 expression. Carbonic anhydrase II associates with and increases water flux through aquyaporin‐1. Water flux through aquaporin‐1 in the thin descending limb (TDL) of the loop of Henle is essential to the concentration of urine, by generating a concentrated medullary interstitium. Car2 is expressed in the thin descending limb. We therefore measured cortical and medullary interstitial concentration in wild‐type and Car2 deficient mice. Mice lacking Car2 had equivalent cortical interstitial osmolarity to WT mice however, they had a reduced medullary interstitial osmolarity. We propose that reduced water flux through aquaporin‐1 in the TDL in the absence of Car2 prevents the generation of a maximally concentrated medullary interstitium and thus the maximal concentration of urine in Car2 deficient mice resulting in polyuria.Support or Funding InformationCanadian Institutes of Health Research
Evidence of Phospho‐degron regulating expression of urate secretory transporter ABCG2
Authors: Woodward Owen M. , Hofherr Alexis , Huang Qiong , Kottgen Michael 
Published: November 2023

ABCG2 is a high capacity urate secretory transporter of the renal proximal tubule. Mutations in ABCG2 cause gout in humans. The ABCG2 patient mutation ABCG2Q141K leads to instability of the ABCG2 nucleotide‐binding domain, which can be rescued by enhancing nucleotide‐binding domain sandwich formation with phosphomimetic amino acid substitutions (G188E, S187D); raising the possibility that phosphorylation of residues in the NBD domain may regulate expression and trafficking of ABCG2. An in silico analysis of ABCG2 revealed a limited number of predicted phosphorylation sites including S195, a serine conserved in the mammalian lineage. The upstream RXRXS represents a target motif for both AKT1 and PKA, and we find both co‐immunoprecipitate with ABCG2. Specifically, endogenous AKT1 can pull down both over expressed ABCG2 in HEK293 cells as well as endogenous ABCG2 in mouse kidney lysate. AKT1 and ABCG2 transcript co‐localize in the proximal S2 segment of the mammalian nephron (Mark Knepper RNA‐seq database) and inhibiting the AKT1 kinase cascade with PI3K inhibitor LY294002 dramatically up‐regulated ABCG2 expression. Conversely, activating the AKT1 cascade with FBS down‐regulated ABCG2 expression. Replacement of the S195 residue with the phosphomimetic aspartic acid results in significant reduction in expression, localization of ABCG2 protein to peri‐nuclear compartments, and significant sensitivity to the proteasome inhibitor MG132; marking the S195 residue as a Phospho‐degron. Phosphorylation of the well conserved S195 residue may interfere with ATP binding and/or nucleotide‐binding domain sandwich formation, suggesting a novel regulatory mechanism for function and trafficking in ABC transporters.Support or Funding InformationAmerican Heart Association: 14SDG18060004 & Ardea BioSciences
Differential mechanisms of ammonia transport in rat duodenum and colon
Authors: Akiba Yasutada , Kaji Izumi , Said Hyder , Kaunitz Jonathan D 
Published: November 2023

The major source of serum ammonia is colonic luminal bacteria, which contribute to ammonia production from amino acid metabolism. The ammonia transporters, rhesus (Rh) glycoprotein B (RhBG) and C (RhCG), expressed in the GI tract, are implicated in ammonia absorption. Since little is known about ammonia transport in the GI tract, including segmental differences, and since ammonia absorption is a major risk factor for hepatic encephalopathy, we investigated ammonia transport in the duodenum and colon.We measured NH3/NH4+ transport in Ussing chambered mucosa‐submucosa preparation of rat duodenum, and proximal (PC) and distal colon (DC). Isc changes and serosal ammonia concentrations were measured before and after luminal application of NH4Cl (1 – 30 mM). We also perfused a proximal duodenal or distal colonic loop in vivo with an NH4Cl solution while measuring portal venous (PV) ammonia concentrations.Luminal application of NH4Cl rapidly and concentration‐dependently increased Isc in the duodenum, whereas Isc gradually increased in response to NH4Cl in the colon. The peak response of NH4Cl‐induced Isc was duodenum = DC >> PC, while the time to peak was duodenum << PC = DC. NH4Cl‐induced Isc was greater when luminal pH was alkaline (pH 7.4 > 7.0 >> 6.4) in the colon, but pH‐independent in the duodenum. Serosal ammonia appearance was consistent with Isc changes in the duodenum, but inconsistent with Isc changes, and constantly increasing, in the colon. NH4Cl‐induced Isc in the duodenum was sensitive to ouabain, but insensitive to luminal Gd3+ and serosal bumetanide, most likely due to cation absorption. NH4Cl‐induced Isc in the colon was sensitive to luminal Gd3+ and serosal bumetanide, but insensitive to ouabain, suggesting that absorbed ammonia may induce Cl− secretion. Luminal perfusion of the duodenum and DC with NH4Cl similarly increased PV ammonia concentration. Quantitative PCR showed that RhBG was ubiquitously expressed in the GI mucosa, whereas RhCG was expressed in the duodenal mucosa, but not in the PC or DC mucosa.Electrogenic, pH‐independent, ammonia absorption in the duodenum may be explained by apical RhCG‐mediated NH4+ transport, whereas luminal pH‐dependent ammonia absorption in the colon characterized by a gradual increase of Isc may be related to simple NH3 diffusion, followed by stimulated secretion. These results may explain why oral NH4Cl induces acute metabolic acidosis, whereas slow NH3 absorption in the distal colon may be implicated in hepatic encephalopathy.Support or Funding InformationVA Merit Review, NIH R01 DK54221