Effects of Sp1 on IP3R1 protein expression in human mesangial cells / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the effects of specific protein 1 ( Sp1 ) on the TNF-αin-duced expression of inositol 1, 4, 5 trisphosphate receptor type 1 ( IP3R1 ) in human mesangial cells ( HMCs) and to further elucidate the molecular mechanism regarding the decreased glomerular filtration rate ( GFR ) during hepatorenal syndrome .Methods Quantitative real-time polymerase chain reaction and Western blot assay were used to analyze the effects of TNF-αon the expression of IP3R1 at mRNA level and the expression of IP3R1 and Sp1 at protein level in HMCs , respectively.HMCs were transfected with a re-combinant plasmid PGL3-IP3R1 promoter to determine the effects of TNF-αon the activity of IP3R1 promot-er.HMCs were treated with Mithramycin A , an inhibitor of Sp1 binding, and transfected with Sp1-siRNA plasmid respectively to evaluate the expression of IP 3R1 regulated by TNF-α.The role of TNFR1 and TNFR2 in the TNF-αinduced expression of Sp 1 and IP3R1 proteins were detected by Western blot .Results TNF-αincreased the expression of IP3R1 at mRNA level and the expression of IP3R1 and Sp1 at protein lev-el in HMCs.Moreover, the activity of IP3R1 promoter in HMCs was remarkably increased by TNF-αas well.TNF-αinduced expression of IP3R1 was inhibited by Mithramycin A in a concentration dependent manner.HMCs transfected with Sp1-siRNA plasmid showed a significantly decreased expression of IP 3R1 protein.Both anti-TNFR1 and anti-TNFR2 antibodies blocked the TNF-αinduced IP3R1 expression, while only anti-TNFR1 antibodies inhibited the TNF-αinduced Sp1 expression.Conclusion TNF-αmight in-crease the expression of IP3R1 through the TNFR1/Sp1 signaling pathways in HMCs .