Functional and Structural Insights into ASB2α, a Novel Regulator of Integrin-dependent Adhesion of Hematopoietic Cells

By providing contacts between hematopoietic cells and the bone marrow microenvironment, integrins are implicated in cell adhesion and thereby in control of cell fate of normal and leukemia cells. The ASB2 gene, initially identified as a retinoic acid responsive gene and a target of the promyelocytic...

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Published in:The Journal of biological chemistry 2011-09, Vol.286 (35), p.30571-30581
Main Authors: Lamsoul, Isabelle, Burande, Clara F., Razinia, Ziba, Houles, Thibault C., Menoret, Delphine, Baldassarre, Massimiliano, Erard, Monique, Moog-Lutz, Christel, Calderwood, David A., Lutz, Pierre G.
Format: Article
Language:English
Subjects:
ASB
E3 Ubiquitin Ligase
Filamin
Hematopoiesis
Leukemia
Life Sciences
Proteasome
Protein Degradation
Protein Synthesis and Degradation
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Summary:By providing contacts between hematopoietic cells and the bone marrow microenvironment, integrins are implicated in cell adhesion and thereby in control of cell fate of normal and leukemia cells. The ASB2 gene, initially identified as a retinoic acid responsive gene and a target of the promyelocytic leukemia retinoic acid receptor α oncoprotein in acute promyelocytic leukemia cells, encodes two isoforms, a hematopoietic-type (ASB2α) and a muscle-type (ASB2β) that are involved in hematopoietic and myogenic differentiation, respectively. ASB2α is the specificity subunit of an E3 ubiquitin ligase complex that targets filamins to proteasomal degradation. To examine the relationship of the ASB2α structure to E3 ubiquitin ligase function, functional assays and molecular modeling were performed. We show that ASB2α, through filamin A degradation, enhances adhesion of hematopoietic cells to fibronectin, the main ligand of β1 integrins. Furthermore, we demonstrate that a short N-terminal region specific to ASB2α, together with ankyrin repeats 1 to 10, is necessary for association of ASB2α with filamin A. Importantly, the ASB2α N-terminal region comprises a 9-residue segment with predicted structural homology to the filamin-binding motifs of migfilin and β integrins. Together, these data provide new insights into the molecular mechanisms of ASB2α binding to filamin.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M111.220921