PXD031450-2

PXD031450 is an original dataset announced via ProteomeXchange.

Title	Distinct functions of dimeric and monomeric Alix in regulating F-actin assembly and loading of exosomal cargo
Description	Alix is a ubiquitously expressed scaffold protein that participates in numerous cellular processes, relating to the remodeling/repair of membranes and the actin cytoskeleton. Alix exists in monomeric and dimeric/multimeric configurations, but how dimer formation occurs and what role the dimer has in Alix-mediated processes are questions still largely elusive. Here, we reveal a mechanism for Alix homodimerization mediated by disulfide bonds under physiological conditions and demonstrate that Alix dimer is enriched in exosome and F-actin cytoskeleton subcellular fractions. Proteomic analysis of exosomes derived from Alix−/− primary cells underlined Alix indispensable role in loading syntenin into exosomes, thereby regulating the cellular levels of this protein. Using a set of Alix deletion mutants, we could define the function of the Bro1 domain, which is solely required for Alix’ exosomal localization, and that of the V domain, which is needed for recruiting syntenin into exosomes. We reveal an essential role for Cys814 within the disordered proline rich domain (PRD) for Alix dimerization. By mutating this residue, Alix remains exclusively monomeric and, in this configuration, is more effective in loading syntenin into exosomes. In contrast, loss of dimerization affects Alix ability to associate with F-actin, thereby compromising Alix-mediated cytoskeleton remodeling. We propose that by 3 shifting the ratio between its dimeric and monomeric forms, Alix selectively executes two of its main functions, exosomal cargo loading or cytoskeleton remodeling.
HostingRepository	PRIDE
AnnounceDate	2023-11-14
AnnouncementXML	Submission_2023-11-14_07:31:34.478.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Jeroen Demmers
SpeciesList	scientific name: Mus musculus (Mouse); NCBI TaxID: 10090;
ModificationList	No PTMs are included in the dataset
Instrument	Orbitrap Fusion

Revision	Datetime	Status	ChangeLog Entry
0	2022-02-04 15:42:02	ID requested
1	2022-10-14 11:20:36	announced
⏵ 2	2023-11-14 07:31:35	announced	2023-11-14: Updated project metadata.

Qiu X, Campos Y, van de Vlekkert D, Gomero E, Tanwar AC, Kalathur R, Weesner JA, Bongiovanni A, Demmers J, d'Azzo A, Distinct functions of dimeric and monomeric scaffold protein Alix in regulating F-actin assembly and loading of exosomal cargo. J Biol Chem, 298(10):102425(2022) [pubmed]

submitter keyword: exosome, cytoskeleton, disulfide, syntenin,Alix, dimerization, actin, homeostasis

Jeroen Demmers
contact affiliation	Proteomics Center, Erasmus University Medical Center, Rotterdam - NL
contact email	j.demmers@erasmusmc.nl
lab head
Jeroen Demmers
contact affiliation	Proteomics Center, Erasmus University Medical Center, Rotterdam, The Netherlands
contact email	j.demmers@erasmusmc.nl
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD031450
     1. Label: PRIDE project
     2. Name: Distinct functions of dimeric and monomeric Alix in regulating F-actin assembly and loading of exosomal cargo