8.A.70 The Endomembrane Morphogenesis TMEM170A (TMEM170A) Family

The TMEM170A protein plays a role in endoplasmic reticulum (ER) and nuclear envelope (NE) morphogenesis (Christodoulou et al. 2016). TMEM170A localizes in ER and NE membranes. Silencing or overexpressing TMEM170A alters ER shape and morphology. Ultrastructural analysis revealed that down-regulation of TMEM170A specifically induced tubular ER formation, while overexpression of TMEM170A induced ER sheet formation. Additionally, down-regulation of TMEM170A altered nuclear shape and size, decreased the density of nuclear pore complexes (NPCs) in the NE and caused either a reduction in inner nuclear membrane (INM) proteins or their relocalization to the ER. TMEM170A interacts with RTN4, a member of the reticulon family; simultaneous co-silencing of TMEM170A and RTN4 rescued ER, NPC and NE-related phenotypes, implying that these two proteins have antagonistic effects on ER membrane organization, NE and NPC formation.