Amysterious version of the protein calcineurin turns out to be a healer that helps refurbish damaged muscle, as Lara-Pezzi et al. report. The molecule promotes cell division and drives away immune cells that can obstruct repair.
Sparked by rising calcium levels, calcineurin flips on transcription factors that control everything from immune responses to heart development to muscle cell differentiation. The two halves of the protein, CnA and CnB, come in several forms. Scientists discovered a new version of CnA, known as CnAβ1, nearly 20 years ago, but they knew little about its function.
Now, the researchers show that, with CnAβ1, undifferentiated muscle cells divide more quickly and are less likely to specialize. Calcineurin usually exerts its influence by activating the NFAT transcription factors. CnAβ1, however, activated a different signaling pathway and blocked the transcription factor FoxO.
CnAβ1 also sped regrowth of damaged muscle, the team...
