BACKGROUND AND AIM: Proliferation and activation of myofibroblastic hepatic stellate cells (HSCs) in response to growth factors is essential for the development of liver fibrosis. As one of the most potent factors, platelet-derived growth factor (PDGF) activates intracellular signals and contributes to sustained HSCs activation. Growing evidence has suggested that the Ca(2+) signal is involved in PDGF pathways. We showed previously for the first time that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is essential for human HSC proliferation. The inhibition of CaMKII by its specific inhibitor, KN-93, significantly decreased the HSC growth and increased expression of cell cycle suppressive regulators P53 and P21. METHODS: In the present study, we investigated the role of CaMKII in PDGF-induced HSC proliferation and underlying mechanisms. RESULTS: We confirmed that in human HSCs, PDGF significantly increased CaMKII mRNA levels, protein expression, and phosphorylation. The interruption of CaMKII by KN-93, specific inhibitory peptide (AIP), or specific CaMKII knockdown by its siRNA not only attenuated PDGF-induced HSC proliferation but also ERK1/2 phosphorylation. However, CaMKII had no effect on JNK phosphorylation. In addition, inhibitors of ERK1/2 (PD98059) and JNK (SP600125) did not affect CaMKII expression. Interruption of CaMKII-ERK cascade, not JNK signal, inhibited PDGF-induced HSC proliferation. CONCLUSION: We confirmed that CaMKII mediated PDGF-induced human HSC proliferation through ERK1/2 but not the JNK mechanism. Our study shed light on CaMKII as a crucial signal in PDGF-activated HSCs and a potential therapeutic point in hepatic fibrosis.
BACKGROUND AND AIM: Proliferation and activation of myofibroblastic hepatic stellate cells (HSCs) in response to growth factors is essential for the development of liver fibrosis. As one of the most potent factors, platelet-derived growth factor (PDGF) activates intracellular signals and contributes to sustained HSCs activation. Growing evidence has suggested that the Ca(2+) signal is involved in PDGF pathways. We showed previously for the first time that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is essential for humanHSC proliferation. The inhibition of CaMKII by its specific inhibitor, KN-93, significantly decreased the HSC growth and increased expression of cell cycle suppressive regulators P53 and P21. METHODS: In the present study, we investigated the role of CaMKII in PDGF-induced HSC proliferation and underlying mechanisms. RESULTS: We confirmed that in human HSCs, PDGF significantly increased CaMKII mRNA levels, protein expression, and phosphorylation. The interruption of CaMKII by KN-93, specific inhibitory peptide (AIP), or specific CaMKII knockdown by its siRNA not only attenuated PDGF-induced HSC proliferation but also ERK1/2 phosphorylation. However, CaMKII had no effect on JNK phosphorylation. In addition, inhibitors of ERK1/2 (PD98059) and JNK (SP600125) did not affect CaMKII expression. Interruption of CaMKII-ERK cascade, not JNK signal, inhibited PDGF-induced HSC proliferation. CONCLUSION: We confirmed that CaMKII mediated PDGF-induced humanHSC proliferation through ERK1/2 but not the JNK mechanism. Our study shed light on CaMKII as a crucial signal in PDGF-activated HSCs and a potential therapeutic point in hepatic fibrosis.
Authors: Ardeshir Z Hashmi; Wyel Hakim; Emma A Kruglov; Azuma Watanabe; William Watkins; Jonathan A Dranoff; Wajahat Z Mehal Journal: Am J Physiol Gastrointest Liver Physiol Date: 2006-10-19 Impact factor: 4.052
Authors: Piotr Czochra; Borut Klopcic; Erik Meyer; Johannes Herkel; Jose Francisco Garcia-Lazaro; Florian Thieringer; Peter Schirmacher; Stefan Biesterfeld; Peter R Galle; Ansgar W Lohse; Stephan Kanzler Journal: J Hepatol Date: 2006-05-30 Impact factor: 25.083
Authors: Paul J Pfleiderer; Katherine Kun Lu; Michael T Crow; Rebecca S Keller; Harold A Singer Journal: Am J Physiol Cell Physiol Date: 2004-02-04 Impact factor: 4.249
Authors: Margarita A Salas; Carlos A Valverde; Gina Sánchez; Matilde Said; Jesica S Rodriguez; Enrique L Portiansky; Marcia A Kaetzel; John R Dedman; Paulina Donoso; Evangelia G Kranias; Alicia Mattiazzi Journal: J Mol Cell Cardiol Date: 2010-01-06 Impact factor: 5.000