Using Yeast Two-hybrid System To Screen Molecules Interacting With MPem Protein

Pem,a homeobox gene,is expressed in a time and stage specific manner during murine ontogeny.Pem transcripts are abundant in 7- and 8-day mouse embryos,but decrease precipitously thereafter. On Day 9 they become abundant in placenta and yolk sac,persisting there until parturition.Although Pem transcripts are not detectable in most of adult tissues,they are present in reproductive system such as testis,epididymis and ovary. This indicates a important role for Pern during embryogenesis and reproductive development.In order to investigate the function of Pem, we used yeast two-hybrid system to screen a 7-days mouse embryo library. Sequening of the positive clones show that there are 3 significative molecules interacting with mPem: Psap, Brpfl and CDC37.Brpfl ( bromodomain and PHD finger containing 1) includes one bromodomain,two PHD finger and one PWWP motif. We suggest : In the specific stage of embryogenesis and reproductive development, mPem gene is expressed and fold into specific structure. Brpfl 's first PHD finger interacts with mPem, its second PHD finger and bromodomain may both contact the nucleosome. With the structure changing, nucleosome recruits transcription factors binding to the promoter region, which actives the gene transcription and results cell differentiation and other accidents happen.Psap(Prosaposin) and mPem have the similarity in their expression patterns.The mPem-Psap interaction is likely to have a role in male reproductive development and cell differentiation.The identification of the interaction between mPem and CDC37 , a chaperone protein, means the proper structure is important for mPem .With the help of CDC37,mPem folds into proper structure and exerts its function.