Angiomotin-like 1 (AMOTL1), by regulating cell-cell junctions, cell polarity, and cell migration, plays a critical role in organogenesis and development. Recently, multiple studies have identified two hotspot mutations in AMOTL1, Arg157 (R157) and Pro160 (P160), in more than ten distinct families presenting with a spectrum of congenital defects, including facial dysmorphisms and cardiac abnormalities. However, the underlying pathogenic mechanism remains elusive. R157 and P160 are located in the highly conserved Tankyrase-binding domain (TBD) of AMOTL1. Here, we show that both the R157C and P160L mutants fail to interact with Tankyrase 1/2 (TNKS1/2) and Ring finger protein 146 (RNF146), rendering them unable to undergo PARylation (poly ADP-ribosylation), ubiquitination, and subsequent proteasomal degradation. As a result, these mutants are significantly stabilized and accumulate in the cytoplasm. Accumulated AMOTL1 mutants, in turn, disrupt cell junctions and focal adhesions, thereby inhibiting both the velocity and persistence of cell migration. Furthermore, during zebrafish embryonic development, expression of the R157C mutant leads to craniofacial malformations and defects in cardiac function and skeletal muscle. Our study confirms the role of AMOTL1mutations in tissue development and uncovers the pathogenic mechanism at both molecular and cellular levels.
Luo et al. (Tue,) studied this question.