RhBG and RhCG, the Putative Ammonia Transporters, Are Expressed in the Same Cells in the Distal Nephron

Eladari, Dominique; Cheval, Lydie; Lopez, Claude; Goossens, D.; Colin, Yves; Cartron, Jean‐Pierre; Paillard, Michel; Chambrey, Régine

doi:10.1097/01.asn.0000050413.43662.55

Cited by 137 publications

(142 citation statements)

References 22 publications

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“…The amino acid sequences of these three Rh genes share high homology to known Rh sequences in the GenBank. Since all three Rh proteins contain potential N-glycosylation sites, they are probably expressed as glycoproteins, similar to their mammalian counterparts (Quentin et al, 2003). K. marmoratus RhBG shares higher sequence homology to three-spined stickleback (Gasterosteus aculeatus) (data not shown), which C. Y. C. Hung and others and RhCG2 in control (0·mmol·l -1 ammonia) and ammonia-exposed (2·mmol·l -1 ammonia) K. marmaratus.…”

Section: Discussionmentioning

confidence: 87%

“…In the mammalian kidney, polarized localization of the Rh proteins is observed in epithelial cells of specific regions, including the renal collecting segment and the collecting duct, with RhBG expression in the basolateral membrane and RhCG in the apical membrane (Quentin et al, 2003;Verlander et al, 2003). Such polarized localization is also present in the pufferfish.…”

Section: Discussionmentioning

confidence: 99%

“…FGMFVTLVFASVGGSLGGLLLRLPFLDSPPDSQCFEDQVYWEVPGEQETET-QRPLRGGESDTRA--- THE JOURNAL OF EXPERIMENTAL BIOLOGY been shown to be glycoproteins (Quentin et al, 2003) and therefore, potential N-glycosylation sites on killifish Rh protein sequences were predicted via NetNGlyc 1.0 Server at http://www.cbs.dtu.dk/services/NetNGlyc.…”

Section: Kryptolebias Marmoratus Lslaitlgmallgglivgfilklpmfgappdticfementioning

confidence: 99%

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Rhesus glycoprotein gene expression in the mangrove killifishKryptolebias marmoratusexposed to elevated environmental ammonia levels and air

Hung

Tsui

Wilson³

et al. 2007

Journal of Experimental Biology

116

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SUMMARY The mechanism(s) of ammonia excretion in the presence of elevated external ammonia are not well understood in fish. Recent studies in other organisms have revealed a new class of ammonia transporters, Rhesus glycoprotein genes(Rh genes), which may also play a role in ammonia excretion in fish. The first objective of this study was to clone and characterize Rhgenes in a fish species with a relatively high tolerance to environmental ammonia, the mangrove killifish Kryptolebias marmoratus (formerly Rivulus marmoratus). We obtained full-length cDNAs of three Rh genes in K. marmoratus: RhBG (1736 bp), RhCG1 (1920 bp) and RhCG2 (2021 bp), which are highly homologous with other known Rh gene sequences. Hydropathy analysis revealed that all three Rh genes encode membrane proteins with 10–12 predicted transmembrane domains. RhBG, RhCG1 and RhCG2 are highly expressed in gill tissue, with RhBG also present in skin of K. marmoratus. Exposure to elevated environmental ammonia (2 mmol l–1 NH4HCO3) for 5 days resulted in a modest (+37%) increase in whole-body ammonia levels, whereas gill RhCG2 and skin RhCG1 mRNA levels were upregulated by 5.8- and 7.7-fold, respectively. RhBG mRNA levels were also increased in various tissues, with 3- to 7-fold increases in the liver and skeletal muscle. In a separate group of killifish exposed to air for 24 h, RhCG1 and RhCG2 mRNA levels were elevated by 4- to 6-fold in the skin. Thus, the multifold induction of Rh mRNA levels in excretory tissues (gills and skin) and internal tissues in response to conditions that perturb normal ammonia excretion suggests that RhBG, RhCG1 and RhCG2 may be involved in facilitating ammonia transport in this species. Furthermore, the findings support earlier studies demonstrating that the skin is an important site of ammonia excretion in K. marmoratus.

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Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Kryptolebias Marmoratus Lslaitlgmallgglivgfilklpmfgappdticfementioning

confidence: 99%

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Rhesus glycoprotein gene expression in the mangrove killifishKryptolebias marmoratusexposed to elevated environmental ammonia levels and air

Hung

Tsui

Wilson³

et al. 2007

Journal of Experimental Biology

116

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“…NH 4 ϩ could pass freely across lipid bilayers through concentration gradients or could be transported by specific carriers (29). The distribution of NH 4 ϩ into the urine augments the effects of the increase in ammoniagenesis on acid-base balance in as much as only ammonia excreted in the urine corresponds to a bicarbonate gain.…”

Section: Discussionmentioning

confidence: 99%

Kidney Protein Dynamics and Ammoniagenesis in Humans with Chronic Metabolic Acidosis

Garibotto

Asioli²,

Robaudo³

et al. 2004

Journal of the American Society of Nephrology

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Abstract. To evaluate the effects of chronic metabolic acidosis on protein dynamics and amino acid oxidation in the human kidney, a combination of organ isotopic ( 14 C-leucine) and mass-balance techniques in 11 subjects with normal renal function undergoing venous catheterizations was used. Five of 11 studies were performed in the presence of metabolic acidosis. In subjects with normal acid-base balance, kidney protein degradation was 35% to 130% higher than protein synthesis, so net protein leucine balance was markedly negative. In acidemic subjects, kidney protein degradation was no different from protein synthesis and was significantly lower (P Ͻ 0.05) than in controls. Kidney leucine oxidation was similar in both groups. Urinary ammonia excretion and total ammonia production were 186% and 110% higher, respectively, and more of the ammonia that was produced was shifted into urine (82% versus 65% in acidemic subjects versus controls). In all studies, protein degradation and net protein balance across the kidney were inversely related to urinary ammonia excretion and to the partition of ammonia into urine, but not to total ammonia production, arterial pH, , urinary flow, the uptake of glutamine by the kidney, or the ammonia released into the renal veins. The data show that response of the human kidney to metabolic acidosis includes both changes in amino acid uptake and suppression of protein degradation. The latter effect, which is likely induced by the increase in ammonia excretion and partition into the urine, is potentially responsible for kidney hypertrophy.Both in vitro and in vivo studies in animals have shown that metabolic acidosis causes several biochemical and morphologic changes in tubule cells, which are ultimately associated with kidney hypertrophy (1,2). Protein synthesis and degradation, the determinants of protein metabolism, are key factors in the hypertrophy process. However, information regarding the signals and mechanisms by which metabolic acidosis might cause kidney hypertrophy is still incomplete, and whether these effects take place in the human kidney is unknown. A further complicating element is that the effects of acidosis on protein turnover rates vary in different tissue types, with catabolic events occurring in peripheral tissues and splanchnic organs (3,4).Chronic acidosis causes several metabolic alterations in the renal proximal tubule, including increased H ϩ secretion (1,5), ammonia synthesis (6), and citrate reabsorption (6,7). These changes in tubule function are associated with changes in the activities of a number of proteins, including the apical membrane Na ϩ /H ϩ antiporter (7), glutaminase and glutamate dehydrogenase (8), and phosphoenolpyruvate carboxykinase (9), which may affect intracellular substrate availability for protein turnover, amino acid metabolism and/or transport, and gluconeogenesis. It has been shown that in tubule epithelial cells, the associated increase in ammonia production, rather than the acidosis per se, is responsible for favoring tubular hyper...

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“…Rabbit polyclonal antiserum against the cytoplasmic N terminus of AE1 was a gift from Dr. Carsten Wagner (University of Zürich, Zürich, Switzerland). Rabbit and A-08 mouse polyclonal antibodies raised against, respectively, the cytoplasmic C terminus and extracellular loops of human RhBG have been described previously (1,2,18). Mouse anti-human ankyrin-G and anti-ZO-1 (Alexa Fluor 488-conjugated) monoclonal antibodies were purchased from Invitrogen and Molecular Probes (SaintAubin, France), respectively.…”

Section: Methodsmentioning

confidence: 99%

Evidence of a Structural and Functional Ammonium Transporter RhBG·Anion Exchanger 1·Ankyrin-G Complex in Kidney Epithelial Cells

Genetet

Ripoche

Kim

et al. 2015

Journal of Biological Chemistry

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Background: Up to now, there was no evidence for an interaction of the kidney anion exchanger 1 (kAE1) with ankyrin. Results: kAE1 actually associates with epithelial ankyrin-G and renal ammonium transporter RhBG, which also binds ankyrin-G. Conclusion: RhBG, kAE1 and ankyrin-G form a structural/functional complex in kidney epithelial cell lines. Significance: This complex could participate in the regulation of acid-base homeostasis.

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RhBG and RhCG, the Putative Ammonia Transporters, Are Expressed in the Same Cells in the Distal Nephron

Cited by 137 publications

References 22 publications

Rhesus glycoprotein gene expression in the mangrove killifishKryptolebias marmoratusexposed to elevated environmental ammonia levels and air

Rhesus glycoprotein gene expression in the mangrove killifishKryptolebias marmoratusexposed to elevated environmental ammonia levels and air

Kidney Protein Dynamics and Ammoniagenesis in Humans with Chronic Metabolic Acidosis

Evidence of a Structural and Functional Ammonium Transporter RhBG·Anion Exchanger 1·Ankyrin-G Complex in Kidney Epithelial Cells

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