Septin-7 is indispensable in skeletal muscle regeneration: Calcium Signaling and Excitation–Contraction in Cardiac, Skeletal and Smooth Muscle

• Published in: The Journal of general physiology Vol. 154; no. 9; p. 1
• Main Authors: Telek, Andrea, Fodor, Janos, Dobrosi, Nora, Szabo, Laszlo, Gönczi, Monika, Dienes, Beatrix, Csernoch, Laszlo
• Format: Journal Article
• Language: English
• Published: New York Rockefeller University Press 01.09.2022
• Subjects: Calcium signalling; Cardiac muscle; Cell division; Cell fusion; Cytoskeleton; Gene expression; Injection; Muscle contraction; Musculoskeletal system; Myogenin; Proteins; Recovery of function; Septin; Skeletal muscle; Smooth muscle; Tibialis anterior muscle; Western blotting
• ISSN: 0022-1295; 1540-7748
• DOI: 10.1085/jgp.2021ecc33

Septins are considered as the fourth component of the cytoskeleton, with septin-7 isoform playing a critical role in myogenic cell division and fusion. Skeletal muscle regeneration is a highly orchestrated process that requires many steps, including proper cell division to achieve functional recovery. Here, the role of septin-7 was investigated in this complex process. To this end, muscle injury was induced in wild type BL6/C57 and septin-7–conditional (mer-Cre-mer) knock-down mice by in vivo BaCl2 injection to the left m. tibialis anterior muscle (TA) of the mice (the right m. tibialis anterior muscle was nontreated control). Mice were sacrificed 4 and 14 d later to reflect the early (monitored by PAX7 level) and late (monitored by myogenin level) phases of muscle regeneration. Western blotting was used to follow the changes of septin-7, PAX7, and myogenin expression at the protein level, while changes of mRNA were detected by qPCR. Morphological differences were visualized by HE staining. Levels of septin-7 protein increased 4 and 14 d after injury in BL6/C57 mice and mRNA expression of SEPT7 showed significant elevation both 4 and 14 d after injection in Cre+ mice only, considered to be a compensatory increase of mRNA expression of SEPT7 in order to ensure the appropriate regeneration process. Furthermore, up-regulation of septin-7 protein was more pronounced on day 14 in both Cre− and Cre+ mice, which may indicate its importance in the later phase of regeneration. Level of PAX7 and myogenin were also increased 4 and 14 d after injury in BL6/C57, Cre−, and Cre+ mice, respectively. Taken together, our data suggest the importance of septin-7 in skeletal muscle regeneration.