[Effects of adenovirus-mediated shRNA down-regulates PTEN expression on fibril-binding proteins vinculin, filamin A and cortactin in activated hepatic stellate cells]

Abstract

Objective: To investigate the effect of adenovirus-mediated shRNA down-regulating phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression on vinculin, filamin A, and cortactin in activated hepatic stellate cells (HSCs). Methods: Activated rats hepatic stellate cell line (HSC-T6) was cultured in vitro. Recombinant adenovirus Ad-shRNA/PTEN carrying PTEN targeted RNA interference sequence [short hairpin RNA (shRNA)] and empty control virus Ad-GFP were transfected into HSCs. The PTEN mRNA and protein expression of HSCs in each group were detected by real-time fluorescence quantitative PCR and Western blot. The expressional change of vinculin, filamin A and cortactin in HSCs of each group were detected by confocal laser scanning immunofluorescence microscope. Image-pro plus 6.0 software was used for image analysis and processing. The integrated optical density (IOD) of the fluorescence protein expression was measured. The experiment was divided into three groups: control group (DMEM instead of adenovirus solution in the adenovirus transfection step), Ad-GFP group (transfected with empty virus Ad-GFP only expressing green fluorescent protein), and Ad-shRNA/PTEN group (recombinant adenovirus Ad-shRNA/PTEN carrying shRNA targeting PTEN and expressing green fluorescent protein). One-way analysis of variance was used for comparison of mean value among the three groups, and LSD-test was used for comparison between the groups. Results: shRNA targeted PTEN was successfully transfected and the expression of PTEN mRNA and protein in HSC (P < 0.05) was significantly down-regulated. HSCs vinculin was mainly expressed in the cytoplasm. HSCs vinculin fluorescence IOD in the Ad-shRNA/PTEN group (19 758.83 ± 1 520.60) was higher than control (7 737.16 ± 279.93) and Ad-GFP group (7 725.50 ± 373.03) (P < 0.05), but there was no statistically significant difference between control group and Ad-GFP group (P > 0.05). There was no statistically significant difference in the fluorescence IOD of Filamin A among the three groups (P > 0.05), but the subcellular distribution of Filamin A among the three groups were changed. Filamin A in the Ad-shrNA /PTEN HSC group was mainly distributed in the cytoplasm. Filamin A HSC was mainly located in the nucleus.The filamin A HSC in the control group and Ad-GFP group was mainly located in the nucleus. The nucleocytoplasmic ratio of Filamin A in the AD-shrNA /PTEN group (0.60 ± 0.15) was significantly lower than control group (1.20 ± 0.15) and Ad-GFP group (1.08 ± 0.23), P < 0.05. but there was no statistically significant difference in filamin A nucleocytoplasmic ratio of HSC between the control group and the Ad-GFP group (P > 0.05). Cortactin HSCs in the three groups was mainly distributed in the cytoplasm. The cortactin fluorescence IOD of HSCs in the Ad-shRNA/PTEN group was significantly higher than control group (22 959.94 ± 1 710.42) and the Ad-GFP group (22 547.11 ± 1 588.72 ) (P < 0.05), while there was no statistically significant difference in the IOD of cortactin fluorescence in HSCs between the control group and the Ad-GFP group (P > 0.05). Conclusion: The down-regulation of PTEN expression raises the expression of microfilament-binding protein vinculin and cortactin, and changes the subcellular distribution of another microfilament binding protein filamin A, that is, translocation from nucleus to the cytoplasm in activated HSC in vitro.

Keywords: Cortactin; Filamin A; Microfilament-binding protein; Stellate cell; Vinculin.