Antioxidants attenuate high glucose-induced hypertrophic growth in renal tubular epithelial cells.
Hyperglycemia-induced oxidative stress is a key mediator of renal tubular hypertrophy in diabetic nephropathy (DN). The molecular mechanisms of antioxidants responsible for inhibition of renal tubular hypertrophy in DN are incompletely characterized. We now aim at verifying the effects of N-acetylcysteine (NAC) and taurine on cellular hypertrophy in renal tubular epithelial cells under high ambient glucose. We found that NAC and taurine treatments significantly attenuated high glucose (HG)-inhibited cellular growth and HG-induced hypertrophy. HG-induced Raf-1, p42/p44 mitogen-activated protein kinase (MAPK), Janus kinase 2 (JAK2), and signal transducer and activator of transcription 1 (STAT1) and STAT3 (but not STAT5) activation was markedly blocked by NAC and taurine. Moreover, NAC and taurine increased cyclin D1/cdk4 activation and suppressed p21(Waf1/Cip1) and p27(Kip1) expression in HG-treated cells. It seems that apoptosis was not observed in these treatments. There were no changes in bcl-2 and poly(ADP-ribose) polymerase expression, and mitochondrial cytochrome c release. However, NAC or taurine markedly inhibited the stimulation by HG of fibronectin and type IV collagen protein levels. It is concluded that both NAC and taurine significantly attenuated HG-induced activation of the Raf-1/MAPK and the JAK2-STAT1/STAT3 signaling pathways and hypertrophic growth in renal tubular epithelial cells.
Huang
Jau-Shyang
JS
Department of Biological Science and Technology, Chung Hwa University of Medical Technology, Tainan, Taiwan, ROC. jaushyang12@hotmail.com
Chuang
Lea-Yea
LY
Guh
Jinn-Yuh
JY
Huang
Yann-Jia
YJ
Hsu
Min-Shyang
MS
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000009:adverse effects*; D006943:Hyperglycemia / Q000150:complications; D006984:Hypertrophy / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D053612:Janus Kinases / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D050791:STAT Transcription Factors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D013654:Taurine / Q000494:pharmacology
D000975:Antioxidants; D050791:STAT Transcription Factors; D013654:Taurine; D053612:Janus Kinases; D019908:Proto-Oncogene Proteins c-raf; D020929:Mitogen-Activated Protein Kinase Kinases; D005947:Glucose; D000111:Acetylcysteine