Phosphoinositide 3-kinase is required for high glucose-induced hypertrophy and p21WAF1 expression in LLC-PK1 cells.
Transforming growth factor-beta (TGF-beta), Smads, and the cyclin-dependent kinase (cdk) inhibitor p21(WAF1) are important in the pathogenesis of diabetic tubular hypertrophy. Phosphoinositide 3 kinase (PI3K)/Akt kinase activity is increased in diabetic glomerular hypertrophy. Thus, we studied the role of PI3K in high glucose (30 mM)-induced p21(WAF1), Smad2/3, and cell cycle-dependent hypertrophy in LLC-PK1 cells. We found that high glucose time-dependently (1-48 h) increased PI3K/Akt kinase activity. LY294002 (a PI3K inhibitor) attenuated high glucose-induced cell cycle-dependent (G(0)/G(1) phase) hypertrophy at 72 h while attenuating high glucose-induced p21(WAF1) gene transcription and protein expression at 36-48 h. LY294002 also attenuated high glucose-induced binding of p21(WAF1) to the cyclin E/cdk2 complex, whereas attenuating high glucose-induced TGF-beta bioactivity, Smad2/3 phosphorylation, and Smad2/3 DNA-binding activity at 36-48 h. We concluded that PI3K is required for high glucose-induced cell cycle-dependent hypertrophy, p21(WAF1) transcription and expression, p21(WAF1) binding to the cyclin E/cdk2 complex, TGF-beta bioactivity, and Smad2/3 activity in LLC-PK1 cells.
Chuang
T-D
TD
Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Guh
J-Y
JY
Chiou
S-J
SJ
Chen
H-C
HC
Huang
J-S
JS
Yang
Y-L
YL
Chuang
L-Y
LY
D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D019927:Cyclin E / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology*; D007668:Kidney / Q000502:physiology; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D013552:Swine; D016212:Transforming Growth Factor beta / Q000187:drug effects / Q000502:physiology
D002867:Chromones; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005947:Glucose; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D016212:Transforming Growth Factor beta; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one