Abstract: Objective To investigate the effects of dedicator of cytokinesis 1 (Dock180) knockout on proliferation and apoptosis in rat derived H9C2 cardiomyocytes and their mechanisms. Methods A single guide RNA (sgRNA) targeting rat Dock180 gene was designed and constructed using CRISPR/Cas9 system. A plasmid contained above sgRNA was packaged into lentivirus and selected to knockout Dock180 in the cardiomyocytes. A single clone of cardiomyocyte with Dock180 knockout was established. Cardiomyocytes were divided into negative lentivirus group (Cas9, A group), Dock180 knockout group (B group), Cas9 lentivirus hypoxia group (C group), Dock180 knockout hypoxia group (D group). The expression of Dock180 mRNA was examined by RT-PCR, and relevant proteins were detected by Western blot. The cell proliferation rate of the cardiomyocytes was determined by MTT, and the apoptotic rate was measured by flow cytometry. Results Dock180 mRNA and protein were absent in B and D groups. Compared with A and C groups, p-ERK1/2 and Bcl-2 protein expression and cell proliferation rate were lower in B and D groups respectively (P<0.01), while Bax protein expression and cell apoptosis rate were higher in B and D groups respectively (P<0.05, P<0.01); Compared with A group, Dock180 mRNA and protein, p-ERK1/2 and Bcl-2 proteins and cell proliferation rate were reduced, while Bax protein and cell apoptosis rate were increased in C group(P<0.05，P<0.01). Compared with B group, p-ERK1/2 and Bcl-2 proteins and cell proliferation rate were decreased, while Bax protein and cell apoptosis rate were increased in D group(P<0.05，P<0.01). Conclusions Dock180 knockout with CRISPR/Cas9 can inhibit proliferation and promoted apoptosis via p-ERK1/2, Bcl-2 and Bax in H9C2 cardiomyocytes.

Key words: Dock180, cardiomycyte, proliferation, apoptosis