Pub Date : 2024-08-01Epub Date: 2024-06-13DOI: 10.1152/ajprenal.00037.2024
Shujie Shi, Gustavo Frindt, Sarah Christine M Whelan, Lawrence G Palmer
Ubiquitination influences the expression of the epithelial Na+ channel (ENaC). We assessed the mechanisms of selective ubiquitination of the mature, cleaved form of γENaC in both native rodent kidneys and Fisher rat thyroid (FRT) cells expressing the channel heterologously. In both models, singly cleaved and fully cleaved γENaCs were strongly ubiquitinated, implying that the second cleavage releasing an inhibitory peptide was not essential for the process. To see whether location of the protein in or near the apical membrane rather than cleavage per se influences ubiquitination, we studied mutants of γENaC in which cleavage sites are abolished. These subunits were ubiquitinated only when coexpressed with α- and βENaC, facilitating trafficking through the Golgi apparatus. To test whether reaching the apical surface is necessary we performed in situ surface biotinylation and measured ENaC ubiquitination in the apical membrane of rat kidney. Ubiquitination of cleaved γENaC was similar in whole kidney and surface fractions, implying that both apical and subapical channels could be modified. In FRT cells, inhibiting clathrin-mediated endocytosis with Dyngo-4a increased both total and ubiquitinated γENaC at the cell surface. Finally, we tested the idea that increased intracellular Na+ could stimulate ubiquitination. Administration of amiloride to block Na+ entry through the channels did not affect ubiquitination of γENaC in either FRT cells or the rat kidney. However, presumed large increases in cellular Na+ produced by monensin in FRT cells or acute Na+ repletion in rats increased ubiquitination and decreased overall ENaC expression.NEW & NOTEWORTHY We have explored the mechanisms underlying the ubiquitination of the γ subunit of epithelial Na+ channel (ENaC), a process believed to control channel internalization and degradation. We previously reported that the mature, cleaved form of the subunit is selectively ubiquitinated. Here we show that this specificity arises not from the cleavage state of the protein but from its location in the cell. We also show that under some conditions, increased intracellular Na+ can stimulate ENaC ubiquitination.
{"title":"Control of ENaC ubiquitination.","authors":"Shujie Shi, Gustavo Frindt, Sarah Christine M Whelan, Lawrence G Palmer","doi":"10.1152/ajprenal.00037.2024","DOIUrl":"10.1152/ajprenal.00037.2024","url":null,"abstract":"<p><p>Ubiquitination influences the expression of the epithelial Na<sup>+</sup> channel (ENaC). We assessed the mechanisms of selective ubiquitination of the mature, cleaved form of γENaC in both native rodent kidneys and Fisher rat thyroid (FRT) cells expressing the channel heterologously. In both models, singly cleaved and fully cleaved γENaCs were strongly ubiquitinated, implying that the second cleavage releasing an inhibitory peptide was not essential for the process. To see whether location of the protein in or near the apical membrane rather than cleavage per se influences ubiquitination, we studied mutants of γENaC in which cleavage sites are abolished. These subunits were ubiquitinated only when coexpressed with α- and βENaC, facilitating trafficking through the Golgi apparatus. To test whether reaching the apical surface is necessary we performed in situ surface biotinylation and measured ENaC ubiquitination in the apical membrane of rat kidney. Ubiquitination of cleaved γENaC was similar in whole kidney and surface fractions, implying that both apical and subapical channels could be modified. In FRT cells, inhibiting clathrin-mediated endocytosis with Dyngo-4a increased both total and ubiquitinated γENaC at the cell surface. Finally, we tested the idea that increased intracellular Na<sup>+</sup> could stimulate ubiquitination. Administration of amiloride to block Na<sup>+</sup> entry through the channels did not affect ubiquitination of γENaC in either FRT cells or the rat kidney. However, presumed large increases in cellular Na<sup>+</sup> produced by monensin in FRT cells or acute Na<sup>+</sup> repletion in rats increased ubiquitination and decreased overall ENaC expression.<b>NEW & NOTEWORTHY</b> We have explored the mechanisms underlying the ubiquitination of the γ subunit of epithelial Na<sup>+</sup> channel (ENaC), a process believed to control channel internalization and degradation. We previously reported that the mature, cleaved form of the subunit is selectively ubiquitinated. Here we show that this specificity arises not from the cleavage state of the protein but from its location in the cell. We also show that under some conditions, increased intracellular Na<sup>+</sup> can stimulate ENaC ubiquitination.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444504/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141312469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-07-11DOI: 10.1152/ajprenal.00077.2024
Dexter L Lee, Clintoria R Williams, Keisa W Mathis, Jan M Williams, Corey Reynolds, Adrienne L King
{"title":"Tips on navigating the first year of graduate school for individuals from historically excluded backgrounds.","authors":"Dexter L Lee, Clintoria R Williams, Keisa W Mathis, Jan M Williams, Corey Reynolds, Adrienne L King","doi":"10.1152/ajprenal.00077.2024","DOIUrl":"10.1152/ajprenal.00077.2024","url":null,"abstract":"","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141592393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-06DOI: 10.1152/ajprenal.00019.2024
Debra L Irsik, Jian-Kang Chen, Wendy B Bollag, Carlos M Isales
Chronic kidney disease is the loss of renal function that can occur from aging or through a myriad of other disease states. Rising serum concentrations of kynurenine, a tryptophan metabolite, have been shown to correlate with increasing severity of chronic kidney disease. This study used chronic intravenous infusion in conscious male Sprague-Dawley rats to test the hypothesis that kynurenine can induce renal damage and promote alterations in blood pressure, heart rate, and decreased renal function. We found that kynurenine infusion increased mean arterial pressure, increased the maximum and minimum range of heart rate, decreased glomerular filtration rate, and induced kidney damage in a dose-dependent manner. This study shows that kynurenine infusion can promote kidney disease in healthy, young rats, implying that the increase in kynurenine levels associated with chronic kidney disease may establish a feed-forward mechanism that exacerbates the loss of renal function.NEW & NOTEWORTHY In humans, an elevated serum concentration of kynurenine has long been associated with negative outcomes in various disease states as well as in aging. However, it has been unknown whether these increased kynurenine levels are mediating the disorders or simply associated with them. This study shows that chronically infusing kynurenine can contribute to the development of hypertension and kidney impairment. The mechanism of this action remains to be determined in future studies.
{"title":"Chronic infusion of the tryptophan metabolite kynurenine increases mean arterial pressure in male Sprague-Dawley rats.","authors":"Debra L Irsik, Jian-Kang Chen, Wendy B Bollag, Carlos M Isales","doi":"10.1152/ajprenal.00019.2024","DOIUrl":"10.1152/ajprenal.00019.2024","url":null,"abstract":"<p><p>Chronic kidney disease is the loss of renal function that can occur from aging or through a myriad of other disease states. Rising serum concentrations of kynurenine, a tryptophan metabolite, have been shown to correlate with increasing severity of chronic kidney disease. This study used chronic intravenous infusion in conscious male Sprague-Dawley rats to test the hypothesis that kynurenine can induce renal damage and promote alterations in blood pressure, heart rate, and decreased renal function. We found that kynurenine infusion increased mean arterial pressure, increased the maximum and minimum range of heart rate, decreased glomerular filtration rate, and induced kidney damage in a dose-dependent manner. This study shows that kynurenine infusion can promote kidney disease in healthy, young rats, implying that the increase in kynurenine levels associated with chronic kidney disease may establish a feed-forward mechanism that exacerbates the loss of renal function.<b>NEW & NOTEWORTHY</b> In humans, an elevated serum concentration of kynurenine has long been associated with negative outcomes in various disease states as well as in aging. However, it has been unknown whether these increased kynurenine levels are mediating the disorders or simply associated with them. This study shows that chronically infusing kynurenine can contribute to the development of hypertension and kidney impairment. The mechanism of this action remains to be determined in future studies.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141261821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-13DOI: 10.1152/ajprenal.00089.2024
Hayden W Hess, Tyler B Baker, Macie L Tarr, Roger S Zoh, Blair D Johnson, David Hostler, Zachary J Schlader
We tested the hypothesis that compliance with the National Institute for Occupational Safety and Health (NIOSH) heat stress recommendations will prevent reductions in glomerular filtration rate (GFR) across a range of wet-bulb globe temperatures (WBGTs) and work-rest ratios at a fixed work intensity. We also tested the hypothesis that noncompliance would result in a reduction in GFR compared with a work-rest matched compliant trial. Twelve healthy adults completed five trials (four NIOSH compliant and one noncompliant) that consisted of 4 h of exposure to a range of WBGTs. Subjects walked on a treadmill (heat production: approximately 430 W) and work-rest ratios (work/h: 60, 45, 30, and 15 min) were prescribed as a function of WBGT (24°C, 26.5°C, 28.5°C, 30°C, and 36°C), and subjects drank a sport drink ad libitum. Peak core temperature (TC) and percentage change in body weight (%ΔBW) were measured. Creatinine clearance measured pre- and postexposure provided a primary marker of GFR. Peak TC did not differ among NIOSH-compliant trials (P = 0.065) but differed between compliant versus noncompliant trials (P < 0.001). %ΔBW did not differ among NIOSH-compliant trials (P = 0.131) or between compliant versus noncompliant trials (P = 0.185). Creatinine clearance did not change or differ among compliant trials (P ≥ 0.079). Creatinine clearance did not change or differ between compliant versus noncompliant trials (P ≥ 0.661). Compliance with the NIOSH recommendations maintained GFR. Surprisingly, despite a greater heat strain in a noncompliant trial, GFR was maintained highlighting the potential relative importance of hydration.NEW & NOTEWORTHY We highlight that glomerular filtration rate (GFR) is maintained during simulated occupational heat stress across a range of total work, work-rest ratios, and wet-bulb globe temperatures with ad libitum consumption of an electrolyte and sugar-containing sports drink. Compared with a work-rest matched compliant trial, noncompliance resulted in augmented heat strain but did not induce a reduction in GFR likely due to an increased relative fluid intake and robust fluid conservatory responses.
{"title":"Creatinine clearance is maintained in a range of wet-bulb globe temperatures and work-rest ratios during simulated occupational heat stress.","authors":"Hayden W Hess, Tyler B Baker, Macie L Tarr, Roger S Zoh, Blair D Johnson, David Hostler, Zachary J Schlader","doi":"10.1152/ajprenal.00089.2024","DOIUrl":"10.1152/ajprenal.00089.2024","url":null,"abstract":"<p><p>We tested the hypothesis that compliance with the National Institute for Occupational Safety and Health (NIOSH) heat stress recommendations will prevent reductions in glomerular filtration rate (GFR) across a range of wet-bulb globe temperatures (WBGTs) and work-rest ratios at a fixed work intensity. We also tested the hypothesis that noncompliance would result in a reduction in GFR compared with a work-rest matched compliant trial. Twelve healthy adults completed five trials (four NIOSH compliant and one noncompliant) that consisted of 4 h of exposure to a range of WBGTs. Subjects walked on a treadmill (heat production: approximately 430 W) and work-rest ratios (work/h: 60, 45, 30, and 15 min) were prescribed as a function of WBGT (24°C, 26.5°C, 28.5°C, 30°C, and 36°C), and subjects drank a sport drink ad libitum. Peak core temperature (T<sub>C</sub>) and percentage change in body weight (%ΔBW) were measured. Creatinine clearance measured pre- and postexposure provided a primary marker of GFR. Peak T<sub>C</sub> did not differ among NIOSH-compliant trials (<i>P</i> = 0.065) but differed between compliant versus noncompliant trials (<i>P</i> < 0.001). %ΔBW did not differ among NIOSH-compliant trials (<i>P</i> = 0.131) or between compliant versus noncompliant trials (<i>P</i> = 0.185). Creatinine clearance did not change or differ among compliant trials (<i>P</i> ≥ 0.079). Creatinine clearance did not change or differ between compliant versus noncompliant trials (<i>P</i> ≥ 0.661). Compliance with the NIOSH recommendations maintained GFR. Surprisingly, despite a greater heat strain in a noncompliant trial, GFR was maintained highlighting the potential relative importance of hydration.<b>NEW & NOTEWORTHY</b> We highlight that glomerular filtration rate (GFR) is maintained during simulated occupational heat stress across a range of total work, work-rest ratios, and wet-bulb globe temperatures with ad libitum consumption of an electrolyte and sugar-containing sports drink. Compared with a work-rest matched compliant trial, noncompliance resulted in augmented heat strain but did not induce a reduction in GFR likely due to an increased relative fluid intake and robust fluid conservatory responses.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141312470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
17β-Hydroxysteroid dehydrogenase-13 (HSD17B13), a newly identified lipid droplet-associated protein, plays an important role in the development of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Emerging evidence demonstrates that NASH is an independent risk factor for chronic kidney disease, which is frequently accompanied by renal lipid accumulation. In addition, the HSD17B13 rs72613567 variant is associated with lower levels of albuminuria in patients with biopsy-proven NAFLD. At present, the role of HSD17B13 in lipid accumulation in the kidney is unclear. This study utilized bioinformatic and immunostaining approaches to examine the expression and localization of HSD17B13 along the mouse urinary tract. We found that HSD17B13 is constitutively expressed in the kidney, ureter, and urinary bladder. Our findings reveal for the first time, to our knowledge, the precise localization of HSD17B13 in the mouse urinary system, providing a basis for further studying the pathogenesis of HSD17B13 in various renal and urological diseases.NEW & NOTEWORTHY HSD17B13, a lipid droplet-associated protein, is crucial in nonalcoholic fatty liver disease (NAFLD) development. NAFLD also independently raises chronic kidney disease (CKD) risk, often with renal lipid buildup. However, HSD17B13's role in CKD-related lipid accumulation is unclear. This study makes the first effort to examine HSD17B13 expression and localization along the urinary system, providing a basis for exploring its physiological and pathophysiological roles in the kidney and urinary tract.
{"title":"Expression and localization of HSD17B13 along mouse urinary tract.","authors":"Haibo Zhang, Jiazhen Chang, Zhihong Dai, Qiuming Wang, Rongfang Qiao, Yingzhi Huang, Beibei Ma, Jiuchao Jiang, Chunhua Zhu, Wen Su, Xiaoyan Zhang, Youfei Guan","doi":"10.1152/ajprenal.00069.2024","DOIUrl":"10.1152/ajprenal.00069.2024","url":null,"abstract":"<p><p>17β-Hydroxysteroid dehydrogenase-13 (HSD17B13), a newly identified lipid droplet-associated protein, plays an important role in the development of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Emerging evidence demonstrates that NASH is an independent risk factor for chronic kidney disease, which is frequently accompanied by renal lipid accumulation. In addition, the HSD17B13 rs72613567 variant is associated with lower levels of albuminuria in patients with biopsy-proven NAFLD. At present, the role of HSD17B13 in lipid accumulation in the kidney is unclear. This study utilized bioinformatic and immunostaining approaches to examine the expression and localization of HSD17B13 along the mouse urinary tract. We found that HSD17B13 is constitutively expressed in the kidney, ureter, and urinary bladder. Our findings reveal for the first time, to our knowledge, the precise localization of HSD17B13 in the mouse urinary system, providing a basis for further studying the pathogenesis of HSD17B13 in various renal and urological diseases.<b>NEW & NOTEWORTHY</b> HSD17B13, a lipid droplet-associated protein, is crucial in nonalcoholic fatty liver disease (NAFLD) development. NAFLD also independently raises chronic kidney disease (CKD) risk, often with renal lipid buildup. However, HSD17B13's role in CKD-related lipid accumulation is unclear. This study makes the first effort to examine HSD17B13 expression and localization along the urinary system, providing a basis for exploring its physiological and pathophysiological roles in the kidney and urinary tract.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141081881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1152/ajprenal.00417.2023_COR
{"title":"Corrigendum for McKinzie et al., volume 326, 2024, p. F644-F660.","authors":"","doi":"10.1152/ajprenal.00417.2023_COR","DOIUrl":"https://doi.org/10.1152/ajprenal.00417.2023_COR","url":null,"abstract":"","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141536147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-05-23DOI: 10.1152/ajprenal.00100.2024
Sarah Christine M Whelan, Stephanie M Mutchler, Agnes Han, Catherine Priestley, Lisa M Satlin, Thomas R Kleyman, Shujie Shi
The pore-forming α-subunit of the large-conductance K+ (BK) channel is encoded by a single gene, KCNMA1. BK channel-mediated K+ secretion in the kidney is crucial for overall renal K+ homeostasis in both physiological and pathological conditions. BK channels achieve phenotypic diversity by various mechanisms, including substantial exon rearrangements at seven major alternative splicing sites. However, KCNMA1 alternative splicing in the kidney has not been characterized. The present study aims to identify the major splice variants of mouse Kcnma1 in whole kidney and distal nephron segments. We designed primers that specifically cross exons within each alternative splice site of mouse Kcnma1 and performed real-time quantitative RT-PCR (RT-qPCR) to quantify relative abundance of each splice variant. Our data suggest that Kcnma1 splice variants within mouse kidney are less diverse than in the brain. During postnatal kidney development, most Kcnma1 splice variants at site 5 and the COOH terminus increase in abundance over time. Within the kidney, the regulation of Kcnma1 alternative exon splicing within these two sites by dietary K+ loading is both site and sex specific. In microdissected distal tubules, the Kcnma1 alternative splicing profile, as well as its regulation by dietary K+, are distinctly different than in the whole kidney, suggesting segment and/or cell type specificity in Kcnma1 splicing events. Overall, our data provide evidence that Kcnma1 alternative splicing is regulated during postnatal development and may serve as an important adaptive mechanism to dietary K+ loading in mouse kidney.NEW & NOTEWORTHY We identified the major Kcnma1 splice variants that are specifically expressed in the whole mouse kidney or aldosterone-sensitive distal nephron segments. Our data suggest that Kcnma1 alternative splicing is developmentally regulated and subject to changes in dietary K+.
{"title":"<i>Kcnma1</i> alternative splicing in mouse kidney: regulation during development and by dietary K<sup>+</sup> intake.","authors":"Sarah Christine M Whelan, Stephanie M Mutchler, Agnes Han, Catherine Priestley, Lisa M Satlin, Thomas R Kleyman, Shujie Shi","doi":"10.1152/ajprenal.00100.2024","DOIUrl":"10.1152/ajprenal.00100.2024","url":null,"abstract":"<p><p>The pore-forming α-subunit of the large-conductance K<sup>+</sup> (BK) channel is encoded by a single gene, <i>KCNMA1.</i> BK channel-mediated K<sup>+</sup> secretion in the kidney is crucial for overall renal K<sup>+</sup> homeostasis in both physiological and pathological conditions. BK channels achieve phenotypic diversity by various mechanisms, including substantial exon rearrangements at seven major alternative splicing sites. However, <i>KCNMA1</i> alternative splicing in the kidney has not been characterized. The present study aims to identify the major splice variants of mouse <i>Kcnma1</i> in whole kidney and distal nephron segments. We designed primers that specifically cross exons within each alternative splice site of mouse <i>Kcnma1</i> and performed real-time quantitative RT-PCR (RT-qPCR) to quantify relative abundance of each splice variant. Our data suggest that <i>Kcnma1</i> splice variants within mouse kidney are less diverse than in the brain. During postnatal kidney development, most <i>Kcnma1</i> splice variants at site 5 and the COOH terminus increase in abundance over time. Within the kidney, the regulation of <i>Kcnma1</i> alternative exon splicing within these two sites by dietary K<sup>+</sup> loading is both site and sex specific. In microdissected distal tubules, the <i>Kcnma1</i> alternative splicing profile, as well as its regulation by dietary K<sup>+</sup>, are distinctly different than in the whole kidney, suggesting segment and/or cell type specificity in <i>Kcnma1</i> splicing events. Overall, our data provide evidence that <i>Kcnma1</i> alternative splicing is regulated during postnatal development and may serve as an important adaptive mechanism to dietary K<sup>+</sup> loading in mouse kidney.<b>NEW & NOTEWORTHY</b> We identified the major <i>Kcnma1</i> splice variants that are specifically expressed in the whole mouse kidney or aldosterone-sensitive distal nephron segments. Our data suggest that <i>Kcnma1</i> alternative splicing is developmentally regulated and subject to changes in dietary K<sup>+</sup>.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141081651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-05-09DOI: 10.1152/ajprenal.00225.2023
Xiaofeng Zuo, Brennan Winkler, Kasey Lerner, Daria V Ilatovskaya, Aleksandra S Zamaro, Yujing Dang, Yanhui Su, Peifeng Deng, Wayne Fitzgibbon, Jessica Hartman, Kwon Moo Park, Joshua H Lipschutz
The exocyst and Ift88 are necessary for primary ciliogenesis. Overexpression of Exoc5 (OE), a central exocyst component, resulted in longer cilia and enhanced injury recovery. Mitochondria are involved in acute kidney injury (AKI). To investigate cilia and mitochondria, basal respiration and mitochondrial maximal and spare respiratory capacity were measured in Exoc5 OE, Exoc5 knockdown (KD), Exoc5 ciliary targeting sequence mutant (CTS-mut), control Madin-Darby canine kidney (MDCK), Ift88 knockout (KO), and Ift88 rescue cells. In Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells, these parameters were decreased. In Exoc5 OE and Ift88 rescue cells they were increased. Reactive oxygen species were higher in Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells compared with Exoc5 OE, control, and Ift88 rescue cells. By electron microscopy, mitochondria appeared abnormal in Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells. A metabolomics screen of control, Exoc5 KD, Exoc5 CTS-mut, Exoc5 OE, Ift88 KO, and Ift88 rescue cells showed a marked increase in tryptophan levels in Exoc5 CTS-mut (113-fold) and Exoc5 KD (58-fold) compared with control cells. A 21% increase was seen in Ift88 KO compared with rescue cells. In Exoc5 OE compared with control cells, tryptophan was decreased 59%. To determine the effects of ciliary loss on AKI, we generated proximal tubule-specific Exoc5 and Ift88 KO mice. These mice had loss of primary cilia, decreased mitochondrial ATP synthase, and increased tryptophan in proximal tubules with greater injury following ischemia-reperfusion. These data indicate that cilia-deficient renal tubule cells are primed for injury with mitochondrial defects in tryptophan metabolism.NEW & NOTEWORTHY Mitochondria are centrally involved in acute kidney injury (AKI). Here, we show that cilia-deficient renal tubule cells both in vitro in cell culture and in vivo in mice are primed for injury with mitochondrial defects and aberrant tryptophan metabolism. These data suggest therapeutic strategies such as enhancing ciliogenesis or improving mitochondrial function to protect patients at risk for AKI.
外囊和 Ift88 是初级纤毛生成所必需的。过量表达外囊中心成分 Exoc5(OE)可使纤毛变长并增强损伤恢复。线粒体与急性肾损伤(AKI)有关。为了对纤毛和线粒体进行研究,测量了纤毛和线粒体的基础呼吸和线粒体最大及剩余呼吸能力:这些细胞包括:Exoc5 OE、Exoc5 敲除 (KD)、Exoc5 纤毛靶向序列突变体 (CTS-mut)、对照 MDCK、Ift88 敲除 (KO) 和 Ift88 挽救细胞。在 Exoc5 KD、Exoc5 CTS 突变和 Ift88 KO 细胞中,这些参数都有所下降。而在 Exoc5 OE 和 Ift88 挽救细胞中,这些参数则有所增加。与 Exoc5 OE、对照和 Ift88 挽救细胞相比,Exoc5 KD、Exoc5 CTS-突变和 Ift88 KO 细胞中的活性氧更高。通过 EM,Exoc5 KD、Exoc5 CTS-突变和 Ift88 KO 细胞中的线粒体出现异常。对对照、Exoc5 KD、Exoc5 CTS-突变、Exoc5 OE、Ift88 KO 和 Ift88 挽救细胞进行的代谢组学筛选显示,与对照细胞相比,Exoc5 CTS-突变(113 倍)和 Exoc5 KD(58 倍)细胞中的色氨酸水平显著增加。与拯救细胞相比,Ift88 KO 细胞中的色氨酸含量增加了 21%。Exoc5 OE 与对照细胞相比,色氨酸减少了 59%。为了确定纤毛缺失对 AKI 的影响,我们产生了近端小管特异性 Exoc5 和 Ift88 KO 小鼠。这些小鼠初级纤毛缺失,线粒体 ATP 合酶减少,近端小管色氨酸增加,缺血再灌注后损伤加重。这些数据表明,纤毛缺失的肾小管细胞会因线粒体色氨酸代谢缺陷而受到损伤。
{"title":"Cilia-deficient renal tubule cells are primed for injury with mitochondrial defects and aberrant tryptophan metabolism.","authors":"Xiaofeng Zuo, Brennan Winkler, Kasey Lerner, Daria V Ilatovskaya, Aleksandra S Zamaro, Yujing Dang, Yanhui Su, Peifeng Deng, Wayne Fitzgibbon, Jessica Hartman, Kwon Moo Park, Joshua H Lipschutz","doi":"10.1152/ajprenal.00225.2023","DOIUrl":"10.1152/ajprenal.00225.2023","url":null,"abstract":"<p><p>The exocyst and Ift88 are necessary for primary ciliogenesis. Overexpression of Exoc5 (OE), a central exocyst component, resulted in longer cilia and enhanced injury recovery. Mitochondria are involved in acute kidney injury (AKI). To investigate cilia and mitochondria, basal respiration and mitochondrial maximal and spare respiratory capacity were measured in Exoc5 OE, Exoc5 knockdown (KD), Exoc5 ciliary targeting sequence mutant (CTS-mut), control Madin-Darby canine kidney (MDCK), Ift88 knockout (KO), and Ift88 rescue cells. In Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells, these parameters were decreased. In Exoc5 OE and Ift88 rescue cells they were increased. Reactive oxygen species were higher in Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells compared with Exoc5 OE, control, and Ift88 rescue cells. By electron microscopy, mitochondria appeared abnormal in Exoc5 KD, Exoc5 CTS-mut, and Ift88 KO cells. A metabolomics screen of control, Exoc5 KD, Exoc5 CTS-mut, Exoc5 OE, Ift88 KO, and Ift88 rescue cells showed a marked increase in tryptophan levels in Exoc5 CTS-mut (113-fold) and Exoc5 KD (58-fold) compared with control cells. A 21% increase was seen in Ift88 KO compared with rescue cells. In Exoc5 OE compared with control cells, tryptophan was decreased 59%. To determine the effects of ciliary loss on AKI, we generated proximal tubule-specific Exoc5 and Ift88 KO mice. These mice had loss of primary cilia, decreased mitochondrial ATP synthase, and increased tryptophan in proximal tubules with greater injury following ischemia-reperfusion. These data indicate that cilia-deficient renal tubule cells are primed for injury with mitochondrial defects in tryptophan metabolism.<b>NEW & NOTEWORTHY</b> Mitochondria are centrally involved in acute kidney injury (AKI). Here, we show that cilia-deficient renal tubule cells both in vitro in cell culture and in vivo in mice are primed for injury with mitochondrial defects and aberrant tryptophan metabolism. These data suggest therapeutic strategies such as enhancing ciliogenesis or improving mitochondrial function to protect patients at risk for AKI.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11390130/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140891407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01Epub Date: 2024-05-23DOI: 10.1152/ajprenal.00337.2023
Jun Guo, Zhenhui Yuan, Rong Wang
Zn2+ levels are reported to be correlated with kidney function. We explored the significance of Zn2+ in sepsis-induced acute kidney injury (SI-AKI) through the regulation of sirtuin 7 (SIRT7) activity. The sepsis rat model was established by cecal ligation and perforation (CLP) and intraperitoneally injected with ZnSO4 or SIRT7 inhibitor 97491 (SIRT7i), with renal tubular injury assessed by hematoxylin and eosin staining. In vitro, human renal tubular epithelial cells (HK-2) were induced with lipopolysaccharide to obtain a renal injury cell model, followed by ZnSO4 or SIRT7i and autophagy inhibitor (3-methyladenine) treatment. Interleukin (IL)-1β, IL-18, reactive oxygen species (ROS), Parkin acetylation level, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) expression levels were determined. The renal tubule injury, inflammation condition, and pyroptosis-related and autophagy-related protein levels were assessed. The pyroptosis in kidney tissues and autophagosome formation were observed by transmission electron microscopy. Zn2+ alleviated renal injury in CLP rats and inhibited pyroptosis and its related protein levels by inhibiting SIRT7 activity in septic rat renal tissues. In vitro, Zn2+ increased HK-2 cell viability and reduced KIM-1, NGAL, IL-1β, IL-18, NLRP3 inflammasome, cleaved caspase-1, gasdermin D-N levels, and pyroptotic cell number. Zn2+ increased autophagosome number and LC3BII/LC3BI ratio and decreased TOM20, TIM23, P62, and mitochondrial ROS levels. Zn2+ increased Parkin acetylation by repressing SIRT7 activity. Inhibiting mitophagy partially averted Zn2+-inhibited NLRP3 inflammasome activation and apoptosis in HK-2 cells. Zn2+ upregulated Parkin acetylation by repressing SIRT7 activity to promote mitophagy and inhibit NLRP3 inflammasome activation and pyroptosis, thus improving SI-AKI.NEW & NOTEWORTHY Zn2+ upregulated Parkin acetylation by repressing sirtuin 7 activity to promote mitophagy and inhibit NLRP3 inflammasome activation and pyroptosis, thus improving sepsis-induced acute kidney injury.
{"title":"Zn<sup>2+</sup> improves sepsis-induced acute kidney injury by upregulating SIRT7-mediated Parkin acetylation.","authors":"Jun Guo, Zhenhui Yuan, Rong Wang","doi":"10.1152/ajprenal.00337.2023","DOIUrl":"10.1152/ajprenal.00337.2023","url":null,"abstract":"<p><p>Zn<sup>2+</sup> levels are reported to be correlated with kidney function. We explored the significance of Zn<sup>2+</sup> in sepsis-induced acute kidney injury (SI-AKI) through the regulation of sirtuin 7 (SIRT7) activity. The sepsis rat model was established by cecal ligation and perforation (CLP) and intraperitoneally injected with ZnSO<sub>4</sub> or SIRT7 inhibitor 97491 (SIRT7i), with renal tubular injury assessed by hematoxylin and eosin staining. In vitro, human renal tubular epithelial cells (HK-2) were induced with lipopolysaccharide to obtain a renal injury cell model, followed by ZnSO<sub>4</sub> or SIRT7i and autophagy inhibitor (3-methyladenine) treatment. Interleukin (IL)-1β, IL-18, reactive oxygen species (ROS), Parkin acetylation level, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) expression levels were determined. The renal tubule injury, inflammation condition, and pyroptosis-related and autophagy-related protein levels were assessed. The pyroptosis in kidney tissues and autophagosome formation were observed by transmission electron microscopy. Zn<sup>2+</sup> alleviated renal injury in CLP rats and inhibited pyroptosis and its related protein levels by inhibiting SIRT7 activity in septic rat renal tissues. In vitro, Zn<sup>2+</sup> increased HK-2 cell viability and reduced KIM-1, NGAL, IL-1β, IL-18, NLRP3 inflammasome, cleaved caspase-1, gasdermin D-N levels, and pyroptotic cell number. Zn<sup>2+</sup> increased autophagosome number and LC3BII/LC3BI ratio and decreased TOM20, TIM23, P62, and mitochondrial ROS levels. Zn<sup>2+</sup> increased Parkin acetylation by repressing SIRT7 activity. Inhibiting mitophagy partially averted Zn<sup>2+</sup>-inhibited NLRP3 inflammasome activation and apoptosis in HK-2 cells. Zn<sup>2+</sup> upregulated Parkin acetylation by repressing SIRT7 activity to promote mitophagy and inhibit NLRP3 inflammasome activation and pyroptosis, thus improving SI-AKI.<b>NEW & NOTEWORTHY</b> Zn<sup>2+</sup> upregulated Parkin acetylation by repressing sirtuin 7 activity to promote mitophagy and inhibit NLRP3 inflammasome activation and pyroptosis, thus improving sepsis-induced acute kidney injury.</p>","PeriodicalId":93867,"journal":{"name":"American journal of physiology. Renal physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141082317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}