NLK negatively regulate TGFβsignaling pathway via Smad4 / 重庆医学

ABSTRACT

Objective To study the effect of NLK on TGFβsignaling pathway and explore the molecular mechanism .Methods Protein stability assay was used to determine the influence of NLK on the degradation of Smad 4 .In vivo ubiquitination assay was applied to detect the effect of NLK on the ubiquitination of Smad4 .Luciferase reporter gene assay was used to detect the effect of NLK on CAGA‐luc and 3TP‐luc ,the responsive reporter of TGFβ signaling pathway .Real time PCR was applied to examine the effect of NLK on the expression of p21 and PAI‐1 ,the target genes of TGFβsignaling pathway .Results In HEK293T cell ,over ex‐pression of NLK promotes the degradation and ubiquitination of Smad4 .In HEK293T cells ,Ectopic expression of NLK inhibits the activity of CAGA luc and 3TP luc stimulated by TGFβ.In HepG2 cells ,over expression of NLK inhibits the expression of p21 and PAI 1 ,the target genes of TGFβsignaling pathway .Conclusion NLK promotes the ubiquitination and degradation of Smad4 ,conse‐quently inhibits TGFβsignaling pathway .