Formin 1 regulates microtubule and F-actin organization to support spermatid transport during spermatogenesis in the rat testis
Formin 1 confers actin nucleation by generating long stretches of actin microfilaments to support cell movement, cell shape, and intracellular protein trafficking. Formin 1 is likely involved in microtubule (MT) dynamics due to the presence of a MTB (microtubule binding) domain near its N-terminus. Herein, formin 1 was shown to structurally interact with α-tubulin, the building block of MT, and also EB1 (end binding protein 1, a MT plus(+)-end binding protein that stabilizes MT) in the testis. Knockdown of formin 1 in Sertoli cells with an established tight junction (TJ)-barrier was found to induce down-regulation of detyrosinated MT (a stabilized form of MT), and disorganization of MTs in which MTs were retracted from the cell cortical zone, mediated through a loss of MT polymerization and down-regulation of Ark1/2 signaling kinase. An efficient knockdown of formin 1 in the testis reduced the number of track-like structures conferred by MTs and F-actin considerably, causing defects in spermatid and phagosome transport across the seminiferous epithelium. In summary, formin1 maintains MT and F-actin track-like structures to support spermatid and phagosome transport across the seminiferous epithelium during spermatogenesis.
Li, Nan, Dolores D. Mruk, Elizabeth I. Tang, Will M. Lee, Chris K.C. Wong, and C. Yan Cheng. 2016. "Formin 1 regulates microtubule and F-actin organization to support spermatid transport during spermatogenesis in the rat testis," Endocrinology 157(7): 2894–2908.