[Production of connective tissue growth factor by angiotensin II in human embryonic lung fibroblast via RhoA-ROCK pathway].

Objective: To explore the production of connective tissue growth factor (CTGF) by Angiotensin II (AngII) in human embryonic lung fibroblast via the RhoA-ROCK pathway.

Methods: Human embryonic lung fibroblast (HFL-1) was divided into 4 groups: (1) control group: no stimulation; (2) AngII group: stimulation of AngII (10(-7) mol/L) ; (3) Irbesartan plus AngII group: stimulation by AngII (10(-7) mol/L) with AT-1 receptor antagonist irbesartan (10(-6) mol/L) pre-treatment; (4) Irbesartan plus AngII group: stimulation by AngII (10(-7) mol/L) with ROCK inhibitor Y27632 (10(-6) mol/L) pre-treatment. Then the products of protein and RNA were collected. Western blot and QuantiGene were used to detect the activation of RhoA-Rock pathway and CTGF.

Results: Exploring the affect of irbesartan on AngII through the Western blot analysis of CTGF and RhoA protein expression: the CTGF level was up-regulated by AngII (0.89 ± 0.05 vs control 0.48 ± 0.10, P < 0.01). Such an effect was markedly blocked by a pretreatment of irbesartan (0.72 ± 0.05, P < 0.05). After the use of AngII, the expression of RhoA protein was significantly enhanced (3.40 ± 0.46 vs control 1.77 ± 0.37, P < 0.01) and blunted by a pretreatment of irbesartan (2.27 ± 0.45, P < 0.05). The Western blot analysis of CTGF protein expression showed that AngII caused a robust increase in CTGF (0.62 ± 0.15 vs control 0.16 ± 0.05, P < 0.01). Such an effect was markedly blocked by a pretreatment of Y27632 (0.17 ± 0.04, P < 0.01). The result was similar at the gene level. AngII significantly increased the expression of CTGF mRNA (1.16 ± 0.06 vs control 1.00 ± 0.01, P < 0.01). And it was markedly blocked by a pretreatment of irbesartan (0.99 ± 0.07, P < 0.01) or Y27632 (1.04 ± 0.08, P < 0.05). AngII significantly increased the expression of RhoA mRNA (1.21 ± 0.07 vs control 1.00 ± 0.06, P < 0.01). And it was markedly blocked by a pretreatment of irbesartan (1.00 ± 0.12, P < 0.05) but not Y27632 (1.10 ± 0.05, P > 0.05).

Conclusion: Ang II activates HFL-1 to produce CTGF through the AT-1 receptor. And the RhoA-Rock pathway is involved.