AIM: To study the signal roles of protein kinase C (PKC) and protein kinase A (PKA) in the influence of interferon-gamma (IFN-gamma) on proliferation and collagen synthesis of fibroblasts derived from hypertrophic scar (HS-FB) and normal skin (NS-FB). METHODS: HS-FB and NS-FB were cultured and passaged in Dulbecco modified Eagles medium (DMEM). Activity of PKC and PKA were assayed by transferring phosphorus (32P) into substrate after treatment with IFN-gamma 1000 kU/L at 10, 30, 60, and 120 min. Cell proliferation was determined with MTT assay. The collagen synthesis was measured with [3H]proline incorporation and Type III pre-collagen was determined with radioimmunoassay. RESULTS: After exposure to IFN-gamma 1000 kU/L for 30 min, PKC activity of HS-FB and NS-FB increased from 2.57 +/- 0.14 and 2.13 +/- 0.12 nmol x min(-1) x g(-1) of control to 3.75 +/- 0.19 and 3.36 +/- 0.16 nmol x min(-1) x g(-1), respectively (P < 0.05). After exposure to IFN-gamma 1000 kU/L for 60 and 120 min, PKA activities of HS-FB increased gradually from 0.82 +/- 0.04 nmol x min(-1) x g(-1) of control to 1.03 +/- 0.05 and 1.23 +/- 0.06 nmol x min(-1) x g(-1), respectively (P<0.05). The PKA activities of NS-FB also increased from 0.52 +/- 0.03 nmol x min(-1) x g(-1) of control to 0.68 +/- 0.03 and 0.89 +/- 0.05 nmol x min(-1) x g(-1), respectively (P<0.05). The proliferation and collagen synthesis were enhanced by PKC activator (containing phosphatidylserine, diacylglycerol and Ca2+) and PKA inhibitor [H(7)250 micromol/L, 1-(5-isoquinolinylsulfonyl)-2-methyl piperazine], and inhibited by PKC inhibitor (GF109 250 micromol/L) and PKA activator (cAMP 25 micromol/L) (P<0.01). GF109 abrogated increased proliferation and collagen synthesis by IFN-gamma but it did not affect the inhibitory effects of IFN-gamma. At 120 min H7 reversed the inhibitory functions of IFN-gamma. CONCLUSION: IFN-gamma transiently increased proliferation and collagen synthesis of HS-FB and NS-FB by activation of PKC and subsequently inhibited proliferation and collagen synthesis by activation of PKA. Copyright 2004 Acta Pharmacologica Sinica
AIM: To study the signal roles of protein kinase C (PKC) and protein kinase A (PKA) in the influence of interferon-gamma (IFN-gamma) on proliferation and collagen synthesis of fibroblasts derived from hypertrophic scar (HS-FB) and normal skin (NS-FB). METHODS: HS-FB and NS-FB were cultured and passaged in Dulbecco modified Eagles medium (DMEM). Activity of PKC and PKA were assayed by transferring phosphorus (32P) into substrate after treatment with IFN-gamma 1000 kU/L at 10, 30, 60, and 120 min. Cell proliferation was determined with MTT assay. The collagen synthesis was measured with [3H]proline incorporation and Type III pre-collagen was determined with radioimmunoassay. RESULTS: After exposure to IFN-gamma 1000 kU/L for 30 min, PKC activity of HS-FB and NS-FB increased from 2.57 +/- 0.14 and 2.13 +/- 0.12 nmol x min(-1) x g(-1) of control to 3.75 +/- 0.19 and 3.36 +/- 0.16 nmol x min(-1) x g(-1), respectively (P < 0.05). After exposure to IFN-gamma 1000 kU/L for 60 and 120 min, PKA activities of HS-FB increased gradually from 0.82 +/- 0.04 nmol x min(-1) x g(-1) of control to 1.03 +/- 0.05 and 1.23 +/- 0.06 nmol x min(-1) x g(-1), respectively (P<0.05). The PKA activities of NS-FB also increased from 0.52 +/- 0.03 nmol x min(-1) x g(-1) of control to 0.68 +/- 0.03 and 0.89 +/- 0.05 nmol x min(-1) x g(-1), respectively (P<0.05). The proliferation and collagen synthesis were enhanced by PKC activator (containing phosphatidylserine, diacylglycerol and Ca2+) and PKA inhibitor [H(7)250 micromol/L, 1-(5-isoquinolinylsulfonyl)-2-methyl piperazine], and inhibited by PKC inhibitor (GF109 250 micromol/L) and PKA activator (cAMP 25 micromol/L) (P<0.01). GF109 abrogated increased proliferation and collagen synthesis by IFN-gamma but it did not affect the inhibitory effects of IFN-gamma. At 120 min H7 reversed the inhibitory functions of IFN-gamma. CONCLUSION:IFN-gamma transiently increased proliferation and collagen synthesis of HS-FB and NS-FB by activation of PKC and subsequently inhibited proliferation and collagen synthesis by activation of PKA. Copyright 2004 Acta Pharmacologica Sinica