The. Thap11 Preliminary Study Of The Interaction Of Proteins And Their Functions

THAP11 belongs to the newly identified THAP family which was characterized by the presence of an evolutionarily conserved motif. Many findings suggest that THAP proteins may function as sequence-specific DNA binding factors with roles in cell proliferation, apoptosis, chromatin modification and transcriptional regulation. It has been reported that THAP7 could repress transcription by two kinds of mechanisms: recruit NcoR and HDAC3 to promoter of target genes or block the acetylation of histone. In model animals, THAP proteins participate in cell proliferation through different pathways. In elegans, LIN-36 could interact with tumor suppressor LIN35/Rb and inhibit proliferation of tumor cells. So THAP11 protein may exhibit its biological effect through the interaction with other proteins apart from its direct inhibition of cell proliferation and growth.To further clarify the repressive mechanism of cell proliferation mediated by THAP11, we screen co-partners of THAP11 in adult liver cDNA library by two yeast-hybrid assay and get two proteins. We futher confirm their interaction in vivo through yeast retransformation assay, co-IP technique and colocalization method. KIAA0157 was also a newly identified gene mapping to 10q26, which could encode 311 amino acids with molecular weight around 48KD. Here, we identified KIAA0157 as a ubiquitously espressed gene and frequently down-regulated in several human tumor tissnes. This expression pattern is very similar to THAP11. KIAA0157 expression could inhibit the clony formation of SKNSH cell compared to normal cell and lead to cycle arrest at G0/G1. Furthermore, we found THAP11 could repress transcription of promoter-targeted genes and the repressive domain of THAP11 located at the N terminal 130 amino acids. In addition to a repressive domain, THAP11 may have a transactivation domain at C terminus.