6533b856fe1ef96bd12b32df

RESEARCH PRODUCT

Alix protein is substrate of Ozz-E3 ligase and modulates actin remodeling in skeletal muscle

Simon MoshiachDaniele P. RomancinoAlessandra D'azzoYvan CamposValentina Di FeliceDuran UstekGaetano PaternitiAntonella BongiovanniNaja VerganiXiaohui Qiu

subject

Ubiquitin-Protein LigasesMuscle Fibers Skeletalmacromolecular substancesBiochemistryCell LineMiceCell MovementTwo-Hybrid System TechniquesmedicineCell AdhesionAnimalsProtein Interaction Domains and MotifsPseudopodiaMuscle SkeletalMolecular BiologyActinMice KnockoutbiologyMyogenesisSettore BIO/16 - Anatomia UmanaCalcium-Binding ProteinsUbiquitinationActin remodelingSkeletal muscleUbiquitin-Protein Ligase ComplexesCell BiologyActin cytoskeletonUbiquitin ligaseCell biologyRepressor ProteinsActin CytoskeletonProtein Transportmedicine.anatomical_structureUbiquitin ligase complexbiology.proteinCell Migration Myogenesis Skeletal Muscle Ubiquitin Ligase Ubiquitination Alix F-actin Ozz-E3 Ubiquitin Ligase Skeletal Muscle CellsCortactinCortactinProtein Binding

description

Alix/AIP1 is a multifunctional adaptor protein that participates in basic cellular processes, including membrane trafficking and actin cytoskeleton assembly, by binding selectively to a variety of partner proteins. However, the mechanisms regulating Alix turnover, subcellular distribution, and function in muscle cells are unknown. We now report that Alix is expressed in skeletal muscle throughout myogenic differentiation. In myotubes, a specific pool of Alix colocalizes with Ozz, the substrate-binding component of the muscle-specific ubiquitin ligase complex Ozz-E3. We found that interaction of the two endogenous proteins in the differentiated muscle fibers changes Alix conformation and promotes its ubiquitination. This in turn regulates the levels of the protein in specific subcompartments, in particular the one containing the actin polymerization factor cortactin. In Ozz(-/-) myotubes, the levels of filamentous (F)-actin is perturbed, and Alix accumulates in large puncta positive for cortactin. In line with this observation, we show that the knockdown of Alix expression in C2C12 muscle cells affects the amount and distribution of F-actin, which consequently leads to changes in cell morphology, impaired formation of sarcolemmal protrusions, and defective cell motility. These findings suggest that the Ozz-E3 ligase regulates Alix at sites where the actin cytoskeleton undergoes remodeling.

yearjournalcountryeditionlanguage
2012-02-16
http://hdl.handle.net/10447/75972