The β-Thymosin Enigma

摘要

Actin dynamics in nonmuscle cells is controlled by the availability of actin nucleating sites and actin monomers. Thymosin β-4 (Tβ-4) has been implicated in modulating the availability of actin monomers in a large variety of cells. It together with actin nucleating, severing, and uncapping proteins, harnesses the intrinsic dynamic properties of actin to regulate the actin polymerization response in cells. Over-expression or addition of exogenous Tβ-4 or its homolog, Tβ-10, alters the actin cytoskeleton, and has multiple effects on cellular functions related to motility. Some of these effects are consistent with β-thymosins functioning exclusively as monomer-binding proteins, while others are not. Therefore, the complex pleiotropic effects of β-thymosin in cells may be due to direct and indirect effects on the actin cytoskeleton, as well as modulation of signaling pathways that will impact the cytoskeleton and a variety of cell functions.