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Effect of type 1 diabetes on protein kinase C (PKC) in rat renal medullary thick ascending limb
Author(s) -
YANG JING,
Pollock Jennifer S.,
Carmines Pamela K.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.971.4
Subject(s) - protein kinase c , medicine , endocrinology , calphostin c , calphostin , downregulation and upregulation , chemistry , western blot , superoxide , gene isoform , biology , kinase , biochemistry , enzyme , gene
Type 1 diabetes (T1D) accelerates superoxide production by the medullary thick ascending limb (mTAL), and this phenomenon is markedly attenuated by PKC inhibition ( FASEB J 21:578.6, 2007). We hypothesized that T1D increases PKC activity and the expression of one or more PKC isoforms in the mTAL. mTAL suspensions were prepared from rats with streptozotocin‐induced T1D (20‐25 days after onset; blood glucose = 383 ± 13 mg/dl) and from normal or Sham (vehicle‐treated) rats. Total PKC activity, measured with a commercially‐available kit, was higher in mTALs from T1D rats than those from normal rats (1.38 ± 0.06 vs 0.73 ± 0.05 O.D./μg protein; P < 0.05). Calphostin C (1 μM) significantly reduced PKC activity to similar values (~0.2 O.D./μg protein) in mTALs from both groups. Western blot analysis revealed elevated PKC‐α protein levels (normalized to β‐actin) in mTALs from rats with T1D (170 ± 19% of Sham; P < 0.05). PKC‐β protein levels were also modestly elevated in mTALs from T1D rats (129 ± 9% of Sham; P < 0.05). In contrast, PKC‐δ levels did not differ between groups (values from T1D rats averaged 105 ± 17% of Sham). These data confirm that T1D increases PKC activity in the mTAL, in association with upregulation of PKC‐α and PKC‐β (but not PKC‐δ). We speculate that the changes in PKC‐α and PKC‐β expression may contribute to increased PKC activity and, in turn, to accelerated superoxide production by the mTAL during T1D.