title: Phenotypic behavior of caveolin-3 R26Q, a mutant associated with hyperCKemia, distal myopathy, and rippling muscle disease.
abstract: Four different phenotypes have been associated with CAV3 mutations: limb girdle muscular dystrophy-1C (LGMD-1C), rippling muscle disease (RMD), and distal myopathy (DM), as well as idiopathic and familial hyperCKemia (HCK). Detailed molecular characterization of two caveolin-3 mutations (P104L and DeltaTFT), associated with LGMD-1C, shows them to impart a dominant-negative effect on wild-type caveolin-3, rendering it dysfunctional through sequestration in the Golgi complex. Interestingly, substitution of glutamine for arginine at amino acid position 26 (R26Q) of caveolin-3 is associated not only with RMD but also with DM and HCK. However, the phenotypic behavior of the caveolin-3 R26Q mutation has never been evaluated in cultured cells. Thus we characterized the cellular and molecular properties of the R26Q mutant protein to better understand how this mutation can manifest as such distinct disease phenotypes. Here, we show that the caveolin-3 R26Q mutant is mostly retained at the level of the Golgi complex. The caveolin-3 R26Q mutant formed oligomers of a much larger size than wild-type caveolin-3 and was excluded from caveolae-enriched membranes. However, caveolin-3 R26Q did not behave in a dominant-negative fashion when coexpressed with wild-type caveolin-3. Thus the R26Q mutation behaves differently from other caveolin-3 mutations (P104L and DeltaTFT) that have been previously characterized. These data provide a possible explanation for the scope of the various disease phenotypes associated with the caveolin-3 R26Q mutation. We propose a haploinsufficiency model in which reduced levels of wild-type caveolin-3, although not rendered dysfunctional due to the caveolin-3 R26Q mutant protein, are insufficient for normal muscle cell function.
authors.affiliation: Department of Molecular Pharmacology, The Albert Einstein Cancer Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Federica
authors.initials: F
authors.lastname: Sotgia
authors.forename: Scott E
authors.initials: SE
authors.lastname: Woodman
authors.forename: Gloria
authors.initials: G
authors.lastname: Bonuccelli
authors.forename: Franco
authors.initials: F
authors.lastname: Capozza
authors.forename: Carlo
authors.initials: C
authors.lastname: Minetti
authors.forename: Philipp E
authors.initials: PE
authors.lastname: Scherer
authors.forename: Michael P
authors.initials: MP
authors.lastname: Lisanti
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001120:Arginine / Q000235:genetics; D019556:COS Cells; D051244:Caveolin 3; D022461:Caveolins / Q000235:genetics* / Q000378:metabolism; D002522:Chlorocebus aethiops; D003402:Creatine Kinase / Q000097:blood* / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D005973:Glutamine / Q000235:genetics; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics; D009135:Muscular Diseases / Q000235:genetics; D009136:Muscular Dystrophies / Q000235:genetics*; D009154:Mutation; D041681:NIH 3T3 Cells; D010641:Phenotype
chemical_list: C495548:Cav3 protein, mouse; D051244:Caveolin 3; D022461:Caveolins; D009124:Muscle Proteins; D005973:Glutamine; D001120:Arginine; D003402:Creatine Kinase