Prothymosin α, a protein implicated in the proliferation and survival of lymphocytes

Abstract

Prothymosin α (ProTα) is a 109-11 amino acid protein widely distributed in mammalian tissues and particularly abundant in lymphoid cells. Genomic and proteomic studies led to consider ProTα as a multifunctional protein implicated in nuclear and cytoplasmic functions. The nuclear function of ProTα is related to chromatin activity through its interaction with core histones and proteins involved in chromatin remodelling, whereas, processes related to the phosphorylation, the proteolytic processing to generate Thymosin α1, and the role as anti-apoptotic factor of ProTα, are linked to its cytoplasmic location. Affinity chromatography and co-immunoprecipitation experiments have demonstrated novel interactions of ProTα with acidic proteins such as SET, ANP32A, and ANP32B in the cytoplasm of proliferating lymphocytes. The stabilization of these interactions by chemical cross-linking with formaldehyde shows that they are formed through associations in six acidic complexes which correspond to selective interactions of SET and ANP32 proteins with ProTα. These ProTα-complexes also include cytoplasmic proteins implicated in membrane remodelling and in mitochondrial activity. In conclusion, these novel protein interactions of ProTα observed in proliferation activity and apoptosis studies, suggest that they might be related to mechanisms involved in the proliferation activity and the apoptotic control of lymphocytes.