Header

UZH-Logo

Maintenance Infos

Annexin A2 binding to endosomes and functions in endosomal transport are regulated by tyrosine 23 phosphorylation


Morel, Etienne; Gruenberg, Jean (2009). Annexin A2 binding to endosomes and functions in endosomal transport are regulated by tyrosine 23 phosphorylation. Journal of Biological Chemistry, 284(3):1604-1611.

Abstract

The phospholipid-binding annexin A2 (AnxA2) is known to play a role in the regulation of membrane and actin dynamics, in particular in the endocytic pathway. The protein is present on early endosomes, where it regulates membrane traffic, including the biogenesis of multivesicular transport intermediates destined for late endosomes. AnxA2 membrane association depends on the protein N terminus and membrane cholesterol but does not involve the AnxA2 ligand p11/S100A10. However, the precise mechanisms that control AnxA2 membrane association and function are not clear. In the present study, we have investigated the role of AnxA2 N-terminal phosphorylation in controlling association to endosomal membranes and functions. We found that endosomal AnxA2 was partially tyrosine-phosphorylated and that mutation of Tyr-23 to Ala (AnxA2Y23A), but not of Ser-25 to Ala, impaired AnxA2 endosome association. We then found that the AnxA2Y23A mutant was unable to bind endosomes in vivo, whereas a phospho-mimicking AnxA2 mutant (Y23D) showed efficient endosome binding capacity. Similarly, we found that AnxA2Y23D interacted more efficiently with liposomes in vitro when compared with AnxA2Y23A. To investigate the role of Tyr-23 in vivo, AnxA2 was knocked down with small interfering RNAs, and then cells were recomplemented with RNA interference-resistant forms of the protein. Using this strategy, we could show that AnxA2Y23D, but not AnxA2Y23A, could restore early-to-late endosome transport after AnxA2 depletion. We conclude that phosphorylation of Tyr-23 is essential for proper endosomal association and function of AnxA2, perhaps because it stabilizes membrane-associated protein via a conformational change.

Abstract

The phospholipid-binding annexin A2 (AnxA2) is known to play a role in the regulation of membrane and actin dynamics, in particular in the endocytic pathway. The protein is present on early endosomes, where it regulates membrane traffic, including the biogenesis of multivesicular transport intermediates destined for late endosomes. AnxA2 membrane association depends on the protein N terminus and membrane cholesterol but does not involve the AnxA2 ligand p11/S100A10. However, the precise mechanisms that control AnxA2 membrane association and function are not clear. In the present study, we have investigated the role of AnxA2 N-terminal phosphorylation in controlling association to endosomal membranes and functions. We found that endosomal AnxA2 was partially tyrosine-phosphorylated and that mutation of Tyr-23 to Ala (AnxA2Y23A), but not of Ser-25 to Ala, impaired AnxA2 endosome association. We then found that the AnxA2Y23A mutant was unable to bind endosomes in vivo, whereas a phospho-mimicking AnxA2 mutant (Y23D) showed efficient endosome binding capacity. Similarly, we found that AnxA2Y23D interacted more efficiently with liposomes in vitro when compared with AnxA2Y23A. To investigate the role of Tyr-23 in vivo, AnxA2 was knocked down with small interfering RNAs, and then cells were recomplemented with RNA interference-resistant forms of the protein. Using this strategy, we could show that AnxA2Y23D, but not AnxA2Y23A, could restore early-to-late endosome transport after AnxA2 depletion. We conclude that phosphorylation of Tyr-23 is essential for proper endosomal association and function of AnxA2, perhaps because it stabilizes membrane-associated protein via a conformational change.

Statistics

Citations

57 citations in Web of Science®
59 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

59 downloads since deposited on 07 Dec 2012
16 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:Special Collections > SystemsX.ch
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:2009
Deposited On:07 Dec 2012 08:35
Last Modified:26 Aug 2016 07:32
Publisher:American Society for Biochemistry and Molecular Biology
Series Name:Journal of Biological Chemistry
ISSN:0021-9258
Additional Information:This research was originally published in: Morel, Etienne; Gruenberg, Jean (2009). Annexin A2 binding to endosomes and functions in endosomal transport are regulated by tyrosine 23 phosphorylation. The Journal of biological chemistry, 284(3):1604-1611. © the American Society for Biochemistry and Molecular Biology.
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1074/jbc.M806499200
PubMed ID:18990701

Download