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

Prior research has shown that protein phosphatase 2A (PP2A) can form multiple complexes depending on regulatory subunits. The STRIPAK complex includes striatin, STRIP1, and MOB4. In yeast and C. elegans, STRIP1 is linked to endoplasmic reticulum formation. The sarcoplasmic reticulum (SR) is a specialized ER in muscle cells. This gap motivated investigation into whether STRIP1 contributes to SR organization in muscle. No prior work had resolved how STRIPAK functions in sarcomere structure. The study addresses this by examining C. elegans muscle. The authors propose that STRIPAK may regulate SR and sarcomere architecture. This paper provides specific evidence for that role.

The authors aimed to determine the role of the STRIPAK complex in muscle organization. They focused on C. elegans to study sarcomere and SR structure. The specific problem involved understanding how STRIP1 and striatin function in muscle. The motivation arose from prior findings linking STRIP1 to ER formation. The study sought to clarify whether STRIPAK regulates SR and sarcomeres. Mutations in farl-11 and cash-1 were tested for effects on muscle structure. The authors propose that STRIPAK may be essential for SR and sarcomere organization. This paper provides evidence to support that hypothesis.

The researchers used C. elegans as a model organism for muscle studies. They examined the STRIPAK complex components CASH-1 and FARL-11. Localization studies showed these proteins reside in the SR. Mutations in farl-11 and cash-1 were introduced to test their function. Immunoblotting detected FARL-11 protein levels in mutants. SR structure was analyzed using microscopy and immunostaining. The SR Ca+2 release channel UNC-68 was quantified in mutants. The authors propose that these methods reveal STRIPAK's role in muscle organization.

Missense mutations in farl-11 and cash-1 caused sarcomere disorganization. FARL-11 missense mutations led to undetectable protein by immunoblot. These mutations disrupted SR organization around M-lines. UNC-68 levels were altered in farl-11 mutants. CASH-1 and FARL-11 form a complex in muscle cells. Both proteins localize to the SR in C. elegans. The authors propose that STRIPAK regulates SR and sarcomere structure. This finding supports the hypothesis that STRIPAK is required for muscle organization.

The authors propose that STRIPAK is required for SR organization in muscle. Their findings suggest that STRIP1 and striatin regulate SR and sarcomere structure. The evidence comes from mutations in farl-11 and cash-1. These mutations caused similar sarcomere disorganization. UNC-68 levels were altered in farl-11 mutants. The authors suggest that STRIPAK may regulate SR calcium channels. The study does not claim STRIPAK is essential for all muscle functions. The findings suggest a specific role in SR and sarcomere organization.