title: The ALP-Enigma protein ALP-1 functions in actin filament organization to promote muscle structural integrity in Caenorhabditis elegans.
abstract: Mutations that affect the Z-disk-associated ALP-Enigma proteins have been linked to human muscular and cardiac diseases. Despite their clear physiological significance for human health, the mechanism of action of ALP-Enigma proteins is largely unknown. In Caenorhabditis elegans, the ALP-Enigma protein family is encoded by a single gene, alp-1; thus C. elegans provides an excellent model to study ALP-Enigma function. Here we present a molecular and genetic analysis of ALP-Enigma function in C. elegans. We show that ALP-1 and alpha-actinin colocalize at dense bodies where actin filaments are anchored and that the proper localization of ALP-1 at dense bodies is dependent on alpha-actinin. Our analysis of alp-1 mutants demonstrates that ALP-1 functions to maintain actin filament organization and participates in muscle stabilization during contraction. Reducing alpha-actinin activity enhances the actin filament phenotype of the alp-1 mutants, suggesting that ALP-1 and alpha-actinin function in the same cellular process. Like alpha-actinin, alp-1 also interacts genetically with a connectin/titin family member, ketn-1, to provide mechanical stability for supporting body wall muscle contraction. Taken together, our data demonstrate that ALP-1 and alpha-actinin function together to stabilize actin filaments and promote muscle structural integrity.
authors.affiliation: University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Hsiao-Fen
authors.initials: HF
authors.lastname: Han
authors.forename: Mary C
authors.initials: MC
authors.lastname: Beckerle
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000185:Actinin / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000918:Antibody Specificity; D001696:Biomechanical Phenomena; D017173:Caenorhabditis elegans / Q000166:cytology / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D022082:Cellular Structures / Q000378:metabolism; D064211:Connectin; D060588:LIM Domain Proteins; D008840:Microfilament Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D016596:Vinculin / Q000378:metabolism
chemical_list: C508653:ALP-1 protein, C elegans; D048868:Adaptor Proteins, Signal Transducing; D029742:Caenorhabditis elegans Proteins; D064211:Connectin; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D050505:Mutant Proteins; C577345:ketn-1 protein, C elegans; D000185:Actinin; D016596:Vinculin