Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2)

V. Sorribas, N. Halaihel, K. Puttaparthi, T. Rogers, R. E. Cronin, A. I. Alcalde, J. Aramayona, M. Sarasa, H. Wang, P. Wilson, H. Zajicek, M. Levi

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Background. Renal toxicity is a major side-effect of aminoglycoside antibiotics and is characterized by an early impairment in proximal tubular function. In a previous study, we have shown that gentamicin administration to the rat causes an early impairment in sodium gradient-dependent phosphate (Na/Pi) cotransport activity. The purpose of our current study was to determine the molecular mechanisms of the impairment in Na/pi cotransport activity, specifically the role of the proximal tubular type II Na/Pi cotransporter. Methods. Rats were treated for one, two, and three days with two daily injections of 30 mg/kg body weight gentamicin or the vehicle. Results. Gentamicin caused a progressive decrease in superficial cortical apical brush-border membrane (SC-BBM) Na/Pi cotransporter activity (856 ± 93 in control vs. 545 ± 87 pmol/mg BBM protein in 3-day gentamicin, P < 0.01). Western blot analysis showed a parallel and progressive decrease in SC-BBM Na/Pi cotransporter protein abundance, a 50% decrease after one day of treatment, a 63% decrease after two days of treatment, and an 83% decrease after three days treatment with gentamicin. In contrast, gentamicin treatment had no effect on Na/Pi cotransport activity or Na/Pi cotransporter protein abundance in BBM isolated from the juxtamedullary cortex (JMC-BBM). Immunofluorescence microscopy showed a major decrease in the expression of Na/Pi cotransporter protein in the apical membrane of the proximal convoluted tubule, with progressive intracellular accumulation of Na/Pi protein. Colocalization studies showed that in gentamicin-treated rats, Na/Pi protein was colocalized in the early endosomes and especially in the lysosomes. Northern blot analysis of cortical RNA interestingly showed no reduction in Na/Pi cotransporter mRNA abundance even after three days of gentamicin treatment. Conclusion. We conclude that gentamicin inhibits Na/Pi cotransport activity by causing a decrease in the expression of the type II Na/Pi cotransport protein at the level of the proximal tubular apical BBM and that inhibition of Na/Pi cotransport activity is most likely mediated by post-transcriptional mechanisms.

Original languageEnglish (US)
Pages (from-to)1024-1036
Number of pages13
JournalKidney International
Volume59
Issue number3
DOIs
StatePublished - 2001

Fingerprint

Endocytosis
Gentamicins
Proteins
Microvilli
Membranes
Therapeutics
Endosomes
Aminoglycosides
Lysosomes
Fluorescence Microscopy
Northern Blotting
Western Blotting
Sodium
Phosphates
Body Weight
RNA
Anti-Bacterial Agents
Kidney
Messenger RNA
Injections

Keywords

  • Axial hetergeneity
  • Early endosomes
  • Lysosomes
  • Nephrotoxicity
  • Phosphatidylinositol
  • Renal toxicity
  • Type II Na/pi cotransport activity

ASJC Scopus subject areas

  • Nephrology

Cite this

Sorribas, V., Halaihel, N., Puttaparthi, K., Rogers, T., Cronin, R. E., Alcalde, A. I., ... Levi, M. (2001). Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2). Kidney International, 59(3), 1024-1036. https://doi.org/10.1046/j.1523-1755.2001.0590031024.x

Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2). / Sorribas, V.; Halaihel, N.; Puttaparthi, K.; Rogers, T.; Cronin, R. E.; Alcalde, A. I.; Aramayona, J.; Sarasa, M.; Wang, H.; Wilson, P.; Zajicek, H.; Levi, M.

In: Kidney International, Vol. 59, No. 3, 2001, p. 1024-1036.

Research output: Contribution to journalArticle

Sorribas, V, Halaihel, N, Puttaparthi, K, Rogers, T, Cronin, RE, Alcalde, AI, Aramayona, J, Sarasa, M, Wang, H, Wilson, P, Zajicek, H & Levi, M 2001, 'Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2)', Kidney International, vol. 59, no. 3, pp. 1024-1036. https://doi.org/10.1046/j.1523-1755.2001.0590031024.x
Sorribas V, Halaihel N, Puttaparthi K, Rogers T, Cronin RE, Alcalde AI et al. Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2). Kidney International. 2001;59(3):1024-1036. https://doi.org/10.1046/j.1523-1755.2001.0590031024.x
Sorribas, V. ; Halaihel, N. ; Puttaparthi, K. ; Rogers, T. ; Cronin, R. E. ; Alcalde, A. I. ; Aramayona, J. ; Sarasa, M. ; Wang, H. ; Wilson, P. ; Zajicek, H. ; Levi, M. / Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2). In: Kidney International. 2001 ; Vol. 59, No. 3. pp. 1024-1036.
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AU - Halaihel, N.

AU - Puttaparthi, K.

AU - Rogers, T.

AU - Cronin, R. E.

AU - Alcalde, A. I.

AU - Aramayona, J.

AU - Sarasa, M.

AU - Wang, H.

AU - Wilson, P.

AU - Zajicek, H.

AU - Levi, M.

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N2 - Background. Renal toxicity is a major side-effect of aminoglycoside antibiotics and is characterized by an early impairment in proximal tubular function. In a previous study, we have shown that gentamicin administration to the rat causes an early impairment in sodium gradient-dependent phosphate (Na/Pi) cotransport activity. The purpose of our current study was to determine the molecular mechanisms of the impairment in Na/pi cotransport activity, specifically the role of the proximal tubular type II Na/Pi cotransporter. Methods. Rats were treated for one, two, and three days with two daily injections of 30 mg/kg body weight gentamicin or the vehicle. Results. Gentamicin caused a progressive decrease in superficial cortical apical brush-border membrane (SC-BBM) Na/Pi cotransporter activity (856 ± 93 in control vs. 545 ± 87 pmol/mg BBM protein in 3-day gentamicin, P < 0.01). Western blot analysis showed a parallel and progressive decrease in SC-BBM Na/Pi cotransporter protein abundance, a 50% decrease after one day of treatment, a 63% decrease after two days of treatment, and an 83% decrease after three days treatment with gentamicin. In contrast, gentamicin treatment had no effect on Na/Pi cotransport activity or Na/Pi cotransporter protein abundance in BBM isolated from the juxtamedullary cortex (JMC-BBM). Immunofluorescence microscopy showed a major decrease in the expression of Na/Pi cotransporter protein in the apical membrane of the proximal convoluted tubule, with progressive intracellular accumulation of Na/Pi protein. Colocalization studies showed that in gentamicin-treated rats, Na/Pi protein was colocalized in the early endosomes and especially in the lysosomes. Northern blot analysis of cortical RNA interestingly showed no reduction in Na/Pi cotransporter mRNA abundance even after three days of gentamicin treatment. Conclusion. We conclude that gentamicin inhibits Na/Pi cotransport activity by causing a decrease in the expression of the type II Na/Pi cotransport protein at the level of the proximal tubular apical BBM and that inhibition of Na/Pi cotransport activity is most likely mediated by post-transcriptional mechanisms.

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