Protein kinase C-dependent NAD(P)H oxidase activation induced by type 1 diabetes in renal medullary thick ascending limb

Jing Yang, Pascale H. Lane, Jennifer S. Pollock, Pamela K. Carmines

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Type 1 diabetes provokes a protein kinase C (PKC)-dependent accumulation of superoxide anion in the renal medullary thick ascending limb (mTAL). We hypothesized that this phenomenon involves PKC-dependent NAD(P)H oxidase activation. The validity of this hypothesis was explored using mTAL suspensions prepared from rats with streptozotocin-induced diabetes and from sham (vehicle-treated) rats. Superoxide production was 5-fold higher in mTAL suspensions from diabetic rats compared with suspensions from sham rats. The NAD(P)H oxidase inhibitor apocynin caused an 80% decrease in superoxide production by mTAL from diabetic rats (P<0.05 vs untreated) without altering superoxide production by sham mTAL. NAD(P)H oxidase activity was <2-fold higher in mTAL from diabetic rats than in sham mTAL (P>0.05). Pretreatment with calphostin C (broad-spectrum PKC inhibitor) or rottlerin (PKCδ inhibitor) reduced NAD(P)H oxidase activity by ≈80% in both groups; however, PKCα/β or PKCβ inhibition did not alter NAD(P)H oxidase activity in either group. Protein levels of Nox2, Nox4, and p47phox were significantly higher in diabetic mTAL than in mTAL from sham rats. In summary, elevated superoxide production by mTAL from diabetic rats was normalized by NAD(P)H oxidase inhibition. PKC-dependent, PKCδ-dependent, and total NAD(P)H oxidase activity was greater in mTAL from diabetic rats compared with sham. Protein levels of Nox2, Nox4, and p47phox were increased in mTAL from diabetic rats. We conclude that increased superoxide production by the mTAL during diabetes involves a PKCδ-dependent increase in NAD(P)H oxidase activity in concert with increased protein levels of catalytic and regulatory subunits of the enzyme.

Original languageEnglish (US)
Pages (from-to)468-473
Number of pages6
JournalHypertension
Volume55
Issue number2
DOIs
StatePublished - Feb 2010

Keywords

  • NAD(P)H oxidase
  • Protein kinase C
  • Thick ascending limb
  • Type 1 diabetes

ASJC Scopus subject areas

  • Internal Medicine

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