Anti-apoptotic function of thymosin-β in developing chick spinal motoneurons

Thymosin-βs (Tβs) are water-soluble peptides abundantly present in the cytoplasm and extracellular compartment. The functions of Tβs appear to be pleiotrophic, including actin-remodeling, wound healing, angiogenesis, etc. In the present study, we present the evidence that Tβs have anti-apoptotic activity on developing chick motoneurons (MNs) in vivo. Using in ovo electroporation, we introduced three isoforms of Tβ (Tβ4, Tβ10, and Tβ15) and found the significantly diminished normal and limb bud removal (LBR)-induced programmed cell death. Such anti-apoptotic activity is independent of Tβ's actin remodeling activity. On the other hand, overexpression of Tβs substantially reduced early cell death initiation signal, such as phosphorylation of c-Jun. Collectively, these results suggest that Tβs may prevent apoptosis of neurons via blockade of early apoptogenic signals independent of actin remodeling action.