bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum Glucocorticoid Kinase 1 (SGK1) Expression in Dendritic Cells Contributes to Salt‐Induced Hypertension in Mice
Authors: Birch Wayne , Van Beusecum Justin P , Barbaro Natalia R , MacDowell Zoe , Aden Luul A , Xiao Liang , Pandey Arvind K , Itani Hana A , Harrison David G , Kirabo Annet 
Published: June 2021

Salt‐sensing mechanisms in hypertension involving the kidney have been well studied; however, recent studies suggest that immune cells can sense Na+. Antigen presenting cells like dendritic cells (DCs) critically modulate inflammation by activating T cells and producing cytokines. We recently found that sodium enters DCs through amiloride‐sensitive channels including the alpha and gamma subunits of the epithelial sodium channel (ENaCαγ) and mediates NADPH oxidase‐dependent formation of immunogenic isolevuglandin (IsoLG)‐protein adducts leading to inflammation and hypertension. Here we describe a novel pathway in which the salt sensing kinase serum/glucocorticoid kinase 1 (SGK1) in DCs mediates salt‐induced assembly of ENaCαγ and promotes salt‐sensitive hypertension by activation of the NADPH oxidase and formation of IsoLG‐protein adducts. Mice lacking SGK1 in CD11c+ cells were protected from renal inflammation, endothelial dysfunction and developed blunted hypertension during the high salt feeding phase of the N‐Nitro‐L‐arginine methyl ester hydrochloride (L‐NAME)/high salt model of salt‐sensitive hypertension. DCs treated with high salt exhibited increased expression of ENaCγ which co‐immunoprecipitated with ENaCα. This was associated with increased activation and expression of various NADPH oxidase subunits. Genetic deletion or pharmacological inhibition of SGK1 in DCs prevented the high salt induced expression of ENaCγ (0.04±0.04, WT, 0.05±0.04, WT plus HS and 0.06±0.05, KO plus HS, p<0.01) and ENaCα (0.29±0.20, for WT, 0.28±0.19, for WT plus HS and 0.30±0.24, for KO plus HS, p<0.01). These results indicate that expression of SGK1 in DCs contributes to the pathogenesis of salt‐sensitive hypertension by stabilizing expression of ENaCαγ leading to activation of NADPH oxidase.Support or Funding InformationThis work was supported by the American Heart Association grants POST290900 and SFRN204200, and National Institutes of Health grants K01HL130497, R01HL125865, and R01HL039006.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mucin 1 is Necessary for TrpV5 Localization in the Kidney's Distal Convoluted Tubule and Normal Bone Architecture
Authors: Ray Evan C. , Al‐Bataineh Mohammad , Marciszyn Allison L. , Poland Paul , Santucci Christopher , Robinson Lisa , Blair Harry C. , Hughey Rebecca P. , Kleyman Thomas R. 
Published: June 2021

Mucin 1 (Muc1 in mice and MUC1 in humans) is a heavily glycosylated transmembrane protein expressed in numerous epithelia. Muc1 interacts with other glycoproteins via interaction with galectins, which bind β‐galactoside sugars. Genome‐wide association data suggest a link between MUC1 polymorphism and bone density. MUC1 exogenously expressed in cultured cells physically interacts with calcium‐selective ion channel TRPV5, increasing cell surface expression and activity in a galectin 3‐dependent fashion. TrpV5 knock‐out (KO) mice exhibit impaired reabsorption of filtered Ca2+ in the kidney's distal convoluted tubule (DCT), resulting in hypercalciuria and diminished trabecular and cortical bone thickness. We hypothesize that interaction between Muc1 and TrpV5 is necessary for normal Ca2+ homeostasis and bone architecture. We examined density and architecture in Muc1 KO mice using μCT of lumbar vertebrae. Male Muc1 KO mice exhibit reduced lumbar vertebral cortical and trabecular thickness, with increased surface area/volume. Muc1 KO mice exhibit similar whole‐blood ionized Ca2+ levels, but increased kidney 1‐α‐hydroxylase levels, suggestive of bodily Ca2+ depletion. We observe that TrpV5 is mis‐localized in the DCT of Muc1 KO mice, suggesting that impaired renal tubular Ca2+ reabsorption may contribute to this Ca2+ depletion. Additionally, TrpV5 is mis‐localized in the DCT in galectin‐3 KO mice, consistent with a role for galectin 3 in mediating Muc1‐TrpV5 interaction. Taken together, these findings suggest that Muc1 plays a role in bodily Ca2+ homeostasis and bone physiology by enhancing cell surface expression of TrpV5.Support or Funding InformationNIDDK K08 DK110332, K01 DK109038, P30 DK079307This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Renal Medullary Interstitial Cell‐Specific Knockout of the Endothelin A Receptor Increases Sodium Excretion and Prevents Salt‐Sensitive Hypertension
Authors: Hu Chunyan , Stuart Deborah , Lakshmipathi Jayalakshmi , Harris Raymond C. , Hao Chuan Ming , Kohan Donald E. 
Published: June 2021

The renal medullary vasculature and tubules are well established regulators of arterial blood pressure (BP) and body fluid and Na+ balance, however relatively little is known about the role of renal medullary interstitial cells (RMIC). RMIC produce a variety of potentially BP‐regulating factors in response to hormonal and paracrine stimuli; amongst these, endothelin (ET) activation of RMIC ET A receptors (ETAR) may be of particular importance. To test this system in vivo, we bred ETARf/f mice containing loxP‐flanked exons 6–8 of the EDNRA gene with tamoxifen‐inducible tenascin‐C‐CreER2 knockin mice. Tenascin‐C‐CreER2:ETARf/f (RMIC ETAR−/−) mice were injected with tamoxifen (160 mg/kg IP) for 5 consecutive days at 3 months of age. All experiments were performed 2 weeks after the last injection and littermates of the same genotype without injection were used as controls. Within the kidney, medullary, but not cortical, EDNRA gene recombination was observed. Radiotelemetric BP was similar between control and RMIC ETAR−/− mice on a normal (0.3% Na+) or low (0.03% Na+) salt diet, however 7 days of a high‐salt (3.2% Na+) intake increased BP in control, but not RMIC ETAR−/− mice (RMIC ETAR−/− 124 ± 4 mmHg vs control 133 ± 2 mmHg, n=10, p<0.05). A similar response was found in diastolic BP. Urine volume, urinary Na+ excretion and urinary K+ excretion were higher in high‐salt diet‐treated RMIC ETAR−/− mice compared with control (n=12, p<0.05) particularly during the first 3 days of high salt intake; no apparent differences in food intake were noted. No difference was observed in plasma aldosterone or plasma renin concentration between high‐salt diet fed RMIC ETAR−/− and control mice (n=6). Urinary nitrite/nitrate excretion (UNOx) was increased in high‐salt diet‐treated RMIC ETAR−/− mice (RMIC ETAR−/− 2645 ± 242 nmol/day vs control 1970 ± 251 nmol/day, n=12, p<0.05). We conclude that RMIC‐specific knockout of ETAR prevents high‐salt diet‐induced hypertension and that this is associated with increases in urinary fluid and electrolyte excretion and UNOx. Our data suggest a novel regulatory pathway involving RMIC ETAR in BP and water/electrolyte homeostasis.Support or Funding InformationNHLBI P01 HL136267This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Regulation of ENaC Expression by Paraoxonase 3
Authors: Shi Shujie , Mutchler Stephanie M. , Marciszyn Allison L. , Kleyman Thomas R. 
Published: June 2021

The epithelial sodium channel (ENaC) mediates the rate‐limiting step of Na+ uptake across the apical membrane of specific epithelia. ENaC‐dependent Na+ absorption in the kidney has important roles in regulating extracellular fluid volume, extracellular [K+] and blood pressure. ENaC functional expression is tightly regulated by multiple intracellular and exogenous factors, including molecular chaperones that are implicated in key steps during ENaC biogenesis. We previously showed that ENaC activity was reduced by paraoxonase 2 (PON2) in Xenopus oocytes. PON2–mediated inhibition is associated with reduced surface expression of ENaC, suggesting a role of PON2 in regulating ENaC turnover and/or trafficking. In supporting this notion, PONs are the mammalian orthologues of MEC‐6, a C. elegans ER‐resident chaperone. MEC‐6 is required for the proper assembly and surface expression of the touch‐sensing MEC‐4/MEC‐10 channel in worm touch‐receptor neurons. If the chaperone function is conserved between MEC‐6 and mammalian PONs, we predict other members of this family will also regulate the functional expression of related ion channels. Indeed, we found that PON3 is expressed in principal cells of the distal nephron, where ENaC resides. The expression of PON3 inhibits ENaC activity in Xenopus oocytes. The protease chymotrypsin activates ENaC by releasing the embedded inhibitory tracts, thus increasing channel open probability (Po). We found that chymotrypsin‐mediated ENaC activation was not altered by PON3, suggesting that PON3 does not inhibit ENaC activity by reducing channel Po. In addition, ENaC expression in Fisher rat thyroid cells was reduced by PON3. Future studies will investigate the mechanism by which PON3 regulates ENaC functional expression as well as the potential roles of PON3 in regulating ENaC activity, blood pressure and extracellular [K+] in the Pon3 KO mice. Understanding mechanisms by which PON3 regulates ENaC expression will provide novel insights into both normal and altered ENaC functional states, such as hypertension.Support or Funding InformationDK103834, DK038470, DK079307This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Functional Implications of Sexual Dimorphism of Transporter Patterns along the Rat Nephron
Authors: Hu Rui , McDonough Alicia A , Layton Anita 
Published: June 2021

The goal of this study is to investigate the functional implications of the sexual dimorphism in transporter patterns along the rodent nephron as reported by Veiras et al. (J Am Soc Nephrol 2018). To do so, we developed sex‐specific computational models of water and solute transport from Bowman space to the papillary tip of a superficial nephron of the kidneys of the male and female rats. The models account for the sex differences in expression levels of the apical and basolateral transporters, in single‐nephron glomerular filtration rate, and in tubular dimensions. Model simulations predict that ~70 and 40% of the filtered volume is reabsorbed by the proximal tubule of the male and female rat kidneys, respectively. The lower fractional volume reabsorption in the female rat can be attributed to their smaller transport area and lower aquaporin‐1 expression level. The latter also results in a larger contribution of the paracellular pathway to water transport. Similar fractions of the filtered Na+ are reabsorbed by the male and female proximal tubule models, respectively. The lower fractional Na+ reabsorption in female is due primarily to their smaller transport area, lower Na+/H+‐exchanger (NHE3) activity, and lower claudin‐2 abundance. This results in significantly larger delivery of water and Na+ to the downstream nephron segments in female. Unlike in the proximal tubule, the distal nephron of the female rat exhibits higher expression levels in key Na+ transporters, including Na+‐K+‐Cl− cotransporter, Na+‐Cl− cotransporter, and epithelial Na+ channel. Not only do the higher expression levels of these transporters account for the enhanced water and Na+ transport along the female distal nephron, relative to male, but they may also contribute to the female rat's ability to excrete a saline load more rapidly than male.Support or Funding InformationThis research was supported by the Canada 150 Research Chair program and by the National Institutes of Health: National Institute of Diabetes and Digestive and Kidney Diseases, grant R01DK106102.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cerebral Blood Flow Autoregulation in Hypertensive Models of Pregnancy
Authors: Maeda Kenji J , Younes Subhi T. , Garrett Michael R , Ryan Michael J , Sasser Jennifer M 
Published: June 2021

Cerebral blood flow (CBF) autoregulation is a robust protective mechanism that maintains constant blood flow during changes in perfusion pressure. Although it is well known that major cardiovascular adaptations occur during normal pregnancies, the cerebral vascular adaptations that occur during pregnancy, especially in the setting of hypertensive pregnancies, are poorly understood. Hypertension is typically associated with normal autoregulatory function in the cerebral circulation, although the upper and lower limits of the autoregulatory curve are shifted to higher blood pressures. Previous studies in pregnant Sprague Dawley (SD) rats show that the cerebral autoregulatory curve is shifted to higher pressures compared to nonpregnant rats. The impact of preexisting hypertension on cerebral blood flow autoregulation has not been examined. The current study was performed to test the hypothesis that CBF autoregulation is impaired during pregnancy in the presence of underlying hypertension.Dahl salt‐sensitive (Dahl S) and spontaneously hypertensive (SHR) rats, 19–22 weeks of age, were used because they spontaneously develop hypertension without additional challenges. Female rats were mated with same strain males, and gestational day 1 (G1) of pregnancy was defined by the detection of sperm histologically from a vaginal swab. CBF was assessed on G18–20 in rats anesthetized with Inactin. Briefly, catheters were placed in the femoral artery and vein to monitor blood pressure and continuously and administer phenylephrine, respectively.Laser Doppler flow probes were positioned above two closed cranial windows 3–4 mm lateral and 2mm distal to Bregma to assess relative changes in CBF in response to increases in blood pressure.Linear regression analysis of CBF autoregulatory curves shows significant differences between pregnant and virgin rats across strains (★★, p<0.0001) and between strains in the pregnant rats (★★, p<0.0001, Figure). No significant differences in slopes were observed between strains in the virgin rats.Contrary to our hypothesis, these data show that CBF autoregulation was enhanced during pregnancy in two different models of spontaneous hypertension. Previous studies from our laboratory showed increased vascular and blood brain barrier permeability in pregnant Dahl S rats when compared to virgin littermates. Therefore, these data suggest an uncoupling of cerebral vascular permeability from CBF autoregulation in this model of superimposed preeclampsia.Future studies will investigate the role of pregnancy specific circulating factors that contribute to these changes and their implications on cerebrovascular function.Support or Funding InformationKJM was supported by 5T32HL105324‐09. Work was supported by 1R01HL137673 to MRG, HL136684to MJR, and R01HL134711 to JMS.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Male Mice Heterozygous LSD1 Knockout Gene Prevented the Effect of High Sodium Intake on Renal Fibrosis and AT1 Conformational Status
Authors: Nascimento Mariana Moura , Katayama Isis Akemi , Pojoga Luminita H , Heimann Joel Claudio 
Published: June 2021

AimTo evaluate the effects of dietary salt overload or restriction on renal structure and AT1 conformational status in wild type and LSD1 (lysine specific demethylase 1) deficient mice.MethodsLSD1 deficient (Het) and wild type (WT) mice were maintained on high (HS), low (LS) or normal (NS) sodium intake, for 12 months. Renal fibrosis, glomerular volume, glomerular diameter and AT1 and AT2 receptor conformational status (activated or not activated by agonist ligation) were evaluated at the end of the study.Results: (n=6–17/group)

LS‐WT
LS‐HET
NS‐WT
NS‐HET
HS‐WT
HS‐HET

Renal Fibrosis (%)
1.08±0.03*
1.13±0.04
1.14±0.03*
1.20±0.03
1.23±0.02
1.22±0.02

Glomerular Volume (×106 μm3)
0.25±0.01
0.27±0.01
0.25±0.01
0.23±0.01
0.27±0.01
0.27±0.01

Glomerular Diameter (μm)
82.4±1.78
84.3±2.92
84.0±1.63
81.0±1.31
84.1±1.58
84.7±2.98

Conformational Status AT1R (FI)
16.9±0.81
19.8±1.43
18.8±0.83
21.2±2.10
19.8±0.84&
21.4±0.67

Conformational Status AT2R (FI)
7.08±0.33
7.27±0.38
6.71±0.28
7.12±0.50
7.69±0.32
6.97±0.38

Data are reported as mean±SEM.
p<0.05 vs. HS‐WT and
p<0.05 vs. LS‐WT

ConclusionsInterestingly, high salt intake stimulated renal fibrosis only in WT mice. The same phenomenon was observed in AT1 conformational status. In addition, the dietary salt content did not influence the glomerular volume and diameter in both WT and Het models suggesting that: renal fibrosis development and AT1 conformational status in response to dietary salt overload occur through different mechanisms in WT and Het animals stimulating further studies to elucidate this phenomenon.Support or Funding InformationSupported by FAPESP, CAPES and American Heart AssociationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Deficiency in Pappa2 expression reduces nephron endowment and associates with hypertension and chronic kidney disease in rats
Authors: Kumar Vikash , Yang Chun , Kurth Terry , Geurts Aron , Cowley Allen W 
Published: June 2021

IntroductionRecently, a congenic Dahl salt‐sensitive (SS) 26‐P rat strain containing Pappa2 allele of salt‐insensitive Brown Norway (BN) rat strain was identified which found to exhibit significant protection from salt‐induced hypertension and kidney injury. Pappa2 (pregnancy associated plasma protein A2) was found to be differentially expressed in the kidney and altered by dietary salt intake. Pappa2 is a metalloproteinase which releases IGF by cleaving IGFBP5 and has been found to play an important role in the development of bone size and angiogenesis. It has not been previously been implicated to play a role in kidney development nor contribute to cardiovascular function and hypertension. The present study determined whether Pappa2 contributes to kidney development, particularly nephron number and the relationship of these findings with hypertension and chronic kidney disease in rats.MethodsThe localization of Pappa2 in embryonic E20.5 and postnatal P0 kidneys of SS and 26‐P was determined by immunohistochemistry. CRISPR/Cas9 was used to knockout the Pappa2 gene in 26‐P strain. Acid‐maceration method was used to determine glomeruli per kidney at P50 of Pappa2‐WT and Pappa2‐KO rats. Pappa2‐WT and Pappa2‐KO rats (male; 9 wk age) were implanted with arterial catheters and radiotransmitters to record mean arterial pressure (MAP; 24/d). Urine was collected to assess micro‐albumin excretion rate, as an index of renal injury.ResultsImmunohistochemistry studies found that Pappa2 was localized in the ureteric bud at E20.5 kidneys of 26‐P embryos suggesting that Pappa2 could be important for ureteric branching and nephron endowment. CRISPR‐Cas9 mutation of Pappa2 in the 26‐P rat resulted in a severe deficit in the number of mature nephrons in rats at day 50 (26833 ± 892 glomeruli/kidney in Pappa2‐KO vs 36508 ± 1276 glomeruli/kidney in Pappa2‐WT). MAP of 10 weeks Pappa2‐KO rats which were maintained on a 0.4% NaCl diet since weaning averaged 121 ± 2.3 mmHg compared with Pappa2‐WT rat which averaged 113 ± 1.3 mmHg (P<0.05). Albumin excretion rates (UalbV) averaged 151 ± 42 and 51 ± 26 mg/day in 6 month old Pappa2‐KO and Pappa2‐WT rats fed a 0.4% NaCl diet respectively, and progressively increased to 270 ± 85 and 97 ± 28 mg/day at 9 months of age.ConclusionPappa2 determines nephron number which is closely associated with hypertension and kidney injury in rats.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
An Upstream Short Open Reading Frame in the Angiotensin Type 1 Receptor Regulates the β‐Arrestin Signaling Pathway
Authors: Kadam Parnika S , Ji Hong , Pai Amrita V , Speth Robert , Mueller Susette , Sandberg Kathryn 
Published: June 2021

The angiotensin type 1 receptor (AT1R) plays a critical role in blood pressure control and thus furthering our understanding of its regulation has physiological and clinical significance. We previously showed a short open reading frame (sORF) in exon (E)2 of the 5' leader sequence of the AT1aR mRNA inhibits AT1R mRNA translation and receptor internalization. In this study, we investigated the role of this sORF in AT1R signaling. The sORF start codon in E2 was disrupted by site‐directed mutagenesis [E1,2(−108T),3‐AT1aR] (MT), which along with the wild type unmutated sORF [E1,2,3‐AT1aR] (WT) were cloned into an expression plasmid [EGFPN2]. Human embryonic kidney‐293 cells were then transfected with WT or MT plasmids. No significant differences were found in the time course of Ang II‐induced ERK1/2 activation between 0–80 min at angiotensin doses of 10 nm (n=3) and 100 nM (n=3); however, the peak response to 10 nM Ang II at 5 min was 1.9‐fold higher in cells transfected with MT compared to WT plasmids (p<0.05; n=4). Furthermore, peak ERK1/2 activation was 1.3‐fold higher in cells transfected with MT compared to WT plasmids after stimulation with Sar1,Ile4,Ile8‐Ang II, a biased AT1R agonist which selectively activates the β‐arrestin‐dependent pathway [pERK1/2/total ERK1/2 normalized to AT1R Bmax: WT, 1.8E‐05 ± 9.5E‐07 vs. MT, 2.3E‐05 ± 3.4E‐06, p<0.05; n=3]. A time course of Sar1,Ile4,Ile8‐Ang II‐induced ERK1/2 activation from 0–80 minutes at 30 μM also showed greater ERK1/2 activation in cells transfected with the MT compared to WT plasmids [p<0.05; n=4]. Since β‐arrestins are implicated to play a role in apoptotic signaling, we are also studying the effect of this sORF on Ang II‐induced cell proliferation and both early and late apoptosis by flow cytometry. This study supports our previous findings that a seven amino acid peptide (PEP7) encoded by this sORF is a selective inhibitor of AT1R‐mediated ERK1/2 activation. These findings not only have implications for the regulation of AT1Rs in physiological and pathological conditions but also for the superfamily of G protein coupled receptors, many of which possess sORFs of unknown function in their 5’ leader sequence.Support or Funding InformationNIH/NHLBI R01‐HL121456 to KS NIH TL1 Award TL1TR001431This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.