Objective    To construct plasmids carrying siRNA targeting insulin induced gene 1 (insig-1)

and to observe the effect of insig-1 absence on cholesterol metabolism in mouse macrophagocyte RAW264.7 treated with inflammatory factor.     Methods    Three siRNA expression plasmids (si-1

si-2 and si-3) targeting insig-1 mRNA and one non-homologous negative control plasmid (si-nc) were constructed based on the nucleotide sequence of insig-1

and were identified by enzyme digestion and sequencing. After RAW264.7 cells were transformed with the plasmids

the insig-1 expression was determined by RT-PCR

Western blotting and immunohistochemical assay

and the plasmid with the best inhibitory effect on insig-1 expression was screened out. The cholesterol content of inflammation-induced RAW264.7 cells was measured with enzymatic method and Oil Red O staining.     Results    The siRNA expression plasmids were constructed. The expression of insig-1 mRNA and protein decreased significantly in RAW264.7 cells transformed with si-1

si-2 or si-3 as compared with that in untransformed cells (P0.05)

and the interfering effect of si-2 on insig-1 expression was the best. After insig-1 gene was silenced

inflammation-induced RAW264.7 cells showed significantly increased cholesterol and Oil Red O particles.     Conclusion    Plasmids carrying siRNA targeting insig-1 gene are constructed

and insig-1 absence may enhance the cholesterol uptake of inflammation-induced cells.