FARL-11 (STRIP1/2) is Required for Sarcomere and Sarcoplasmic Reticulum Organization inC. elegans

Abstract

AbstractProtein phosphatase 2A (PP2A) functions in a variety of cellular contexts. PP2A can assemble into four different complexes based on the inclusion of different regulatory or targeting subunits. The B’’’ regulatory subunit “striatin” forms the STRIPAK complex consisting of striatin, a catalytic subunit (PP2AC), striatin interacting protein 1 (STRIP1), and MOB family member 4 (MOB4). In yeast andC. elegans,STRIP1 is required for formation of the endoplasmic reticulum (ER). Since the sarcoplasmic reticulum (SR) is the highly organized muscle-specific version of ER, we sought to determine the function of the STRIPAK complex in muscle usingC. elegans. CASH-1 (striatin) and FARL-11 (STRIP1/2) form a complexin vivo, and each protein is localized to SR. Missense mutations and single amino acid losses infarl-11andcash-1each result in similar sarcomere disorganization. A missense mutation infarl-11shows no detectable FARL-11 protein by immunoblot, disruption of SR organization around M-lines, and altered levels of the SR Ca+2release channel UNC-68.SummaryProtein phosphatase 2A forms a STRIPAK complex when it includes the targeting B’’’ subunit “striatin” and STRIP1. STRIP1 is required for formation of ER. We show that in muscle STRIP1 is required for organization of SR and sarcomeres.