Effect of thymosin beta15 on the branching of developing neurons.

The thymosin betas (Tbetas) are polypeptide regulators of actin dynamics that are critical for the growth and branching of neurites in developing neurons. We found that mRNAs for Tbeta4, Tbeta10, and Tbeta15 were highly expressed in the developing rat brain during neuritogenesis, supporting a role for the Tbetas in this process. Overexpression of the Tbetas increased the number of neurite branches per neuron in cultured hippocampal and cerebral cortex neurons, and Tbeta15 had the greatest effect. Actin binding activity appears to be essential for the branch-promoting activity of Tbetas because two mutants of Tbeta15 lacking monomeric actin binding activity failed to stimulate branch formation. We also found that transfection of siRNA against Tbeta15 reduced branching. Taken together, these data suggest that the three Tbetas, and especially Tbeta15, stimulate neurite branching during brain development.

胸腺素β15对发育中神经元分支的影响。

胸腺素β(tβ)是肌动蛋白动力学的多肽调节剂，对发育神经元中神经突的生长和分支至关重要。我们发现tβ4、tβ10和tβ15的mRNAs在神经突形成过程中在发育中的大鼠脑中高度表达，支持了tβ在这一过程中的作用。Tbetas的过表达增加了培养的海马和大脑皮层神经元中每个神经元的神经突分支的数量，并且Tbeta15具有最大的效果。肌动蛋白结合活性似乎对Tbeta的分支促进活性至关重要，因为缺乏单体肌动蛋白结合活性的Tbeta15的两个突变体不能刺激分支形成。我们还发现针对Tbeta15的siRNA转染减少了分支。综上所述，这些数据表明三种Tbeta，尤其是Tbeta15，在脑发育期间刺激神经突分支。