Study On The Biological Function Of Prothymosin A And DNA Microarray Analysis

Human prothymosin a (ProT a ) is a highly acidic protein which is distributed widely and is high conserved among mammals. Its molecular weight is 13 kDa. The ProT a gene is located at chromosome 2 and it has a gene family of six members. It is a fact that ProT a has many immunomodulatory functions which may be of great benefit to clinical therapy. A ProTa gene of Caucasian has been cloned and its expression product is undertaking clinical trails to tumor patients.In consideration of polymorphism of human gene, a ProTa cDNA of 300bp encoding 100 amino acids was cloned from healthy Chinese peripheral blood monocyte cell s(PBMC) which was accepted by GenBank(Accession:AF 170-294). It was a new subtype of human ProT u and has 86.4% homology with GenBank data. The fusion protein of 37 kDa was expressed in prokaryotic system and its biological function was invested.Compared with control, E-rosste formation rate of human PBMC can be enhanced by fusion ProTa . The rate of concentration of 107mo1/L is 52.7%.A markedly effect of ProTa on cell proliferation was observed. In vitro, it can stimulate proliferation of thymocyes in BALB/c mice with or without ConA(5^gIm1) at the concentration of 107mo1/L(p<0.01). Samely, it enhances splenocytes proliferation alone at 107mo1/L(p<0.0 1), and When incubated with ConA , the lowest effective concentration is 10.10 mol/L(p<0.0l).The result is dependented on the concentrations of ProT a^In our study, ProT a can promote secretion of IL-2 and synthesis of TNF- a IFNa and IFN-γ.When used with or without ConA, ProTa significantly increaesd the secretion of IL-2 at 10^-7 and I 08mo1/L, and IFN- Y at I 07mo1/L in thymus and splenic lymphocytes. On the other hand, it promote the synthesis of TNF-α and IFN-α at 10^-7 mol/L when incubated with LPS(l0μg/ml)in splenic and peritoneal macrophages,respectively.In order to find out the effect of ProT a on mRNA level in splenic lymphocytes of mice, we use a MGEC-40S DNA microarray. It was found that the expression of seven genes have been up-regulated, such as lymphocyte antigen 6 complex(GenBank]D D86232); Mouse chromosome 6 BAC-284H12(AC002397); G0106B08-3 Mus musculus(AW5 36575); Mus musculus protein tyrosine phosphatase(U24700); Mus musculus ribosomal protein L6 (NM 011290); Large multi functional protease 7(X64449); Proliferation-associated gene A(D2 1252), and so on.Our study showed that this new gene has a immunomodulatory activities which is potentially benefit to many diseases and is the base of our further research in the future. We believe that it will be a new drug to apply in clinical therapy.