SPECC1L: a cytoskeletal protein that regulates embryonic tissue dynamics.

Many structural birth defects occur due to failure of tissue movement and fusion events during embryogenesis. Examples of such birth defects include failure of closure of the neural tube, palate, and ventral body wall. Actomyosin forces play a pivotal role in these closure processes, making proteins that regulate actomyosin dynamics a priority when studying the etiology of structural birth defects. SPECC1L (sperm antigen with calponin homology and coiled-coil domains 1 like) cytoskeletal protein associates with microtubules, filamentous actin, non-muscle myosin II (NMII), as well as membrane-associated components of adherens junctions. Patients with SPECC1L mutations show a range of structural birth defects affecting craniofacial development (hypertelorism, cleft palate), ventral body wall (omphalocele), and internal organs (diaphragmatic hernia, bicornuate uterus). Characterization of mouse models indicates that these syndromic mutations utilize a gain-of-function mechanism to affect intra- and supra-cellular actin organization. Interestingly, SPECC1L deficiency appears to affect the efficiency of tissue dynamics, making it an important cytoskeletal regulator to study tissue movement and fusion events during embryonic development. Here we summarize the SPECC1L-related syndrome mutations, phenotypes of Specc1l mouse models, and cellular functions of SPECC1L that highlight how it may regulate embryonic tissue dynamics.