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The membrane scaffold CD82 regulates cell adhesion by altering ?4 integrin stability and molecular density.

ABSTRACT: Hematopoietic stem/progenitor cell (HSPC) interactions with the bone marrow microenvironment are important for maintaining HSPC self-renewal and differentiation. In recent work, we identified the tetraspanin protein, CD82, as a regulator of HPSC adhesion and homing to the bone marrow, although the mechanism by which CD82 mediated adhesion was unclear. In the present study, we determine that CD82 expression alters cell-matrix adhesion, as well as integrin surface expression. By combining the superresolution microscopy imaging technique, direct stochastic optical reconstruction microscopy, with protein clustering algorithms, we identify a critical role for CD82 in regulating the membrane organization of ?4 integrin subunits. Our data demonstrate that CD82 overexpression increases the molecular density of ?4 within membrane clusters, thereby increasing cellular adhesion. Furthermore, we find that the tight packing of ?4 into membrane clusters depend on CD82 palmitoylation and the presence of ?4 integrin ligands. In combination, these results provide unique quantifiable evidence of CD82's contribution to the spatial arrangement of integrins within the plasma membrane and suggest that regulation of integrin density by tetraspanins is a critical component of cell adhesion.

SUBMITTER: Termini CM

PROVIDER: S-EPMC4019488 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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The membrane scaffold CD82 regulates cell adhesion by altering α4 integrin stability and molecular density.

Termini Christina M CM Cotter Maura L ML Marjon Kristopher D KD Buranda Tione T Lidke Keith A KA Gillette Jennifer M JM

Molecular biology of the cell 20140312 10

Hematopoietic stem/progenitor cell (HSPC) interactions with the bone marrow microenvironment are important for maintaining HSPC self-renewal and differentiation. In recent work, we identified the tetraspanin protein, CD82, as a regulator of HPSC adhesion and homing to the bone marrow, although the mechanism by which CD82 mediated adhesion was unclear. In the present study, we determine that CD82 expression alters cell-matrix adhesion, as well as integrin surface expression. By combining the supe ...[more]

PMID: 24623721

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Project description:Adhesive and migratory behavior can be cell type, integrin, and substrate dependent. We have compared integrin and substrate differences using three integrin receptors: ?5?1, ?6?1, and ?L?2 expressed in a common cell type, CHO.B2 cells, which lack integrin ? subunits, as well as in different cell types that express one or more of these integrins. We find that CHO.B2 cells expressing either ?6?1 or ?L?2 integrins migrate and protrude faster and are more directionally persistent on laminin or ICAM-1, respectively, than CHO.B2 cells expressing ?5?1 on fibronectin. Despite rapid adhesion maturation and the presence of large adhesions in both the ?6?1- and ?L?2-expressing cells, they display robust tyrosine phosphorylation. In addition, whereas myosin II regulates adhesion maturation and turnover, protrusion rates, and polarity in cells migrating on fibronectin, surprisingly, it does not have comparable effects in cells expressing ?6?1 or ?L?2. This apparent difference in the integration of myosin II activity, adhesion, and migration arises from alterations in the ligand-integrin-actin linkage (molecular clutch). The elongated adhesions in the protrusions of the ?6?1-expressing cells on laminin or the ?L?2-expressing cells on ICAM-1 display a novel, rapid retrograde flux of integrin; this was largely absent in the large adhesions in protrusions of ?5?1-expressing cells on fibronectin. Furthermore, the force these adhesions exert on the substrate in protrusive regions is reduced compared to similar regions in ?5-expressing cells, and the adhesion strength is reduced. This suggests that intracellular forces are not efficiently transferred from actomyosin to the substratum due to altered adhesion strength, that is, avidity, affinity, or the ligand-integrin-actin interaction. Finally, we show that the migration of fast migrating leukocytes on fibronectin or ICAM-1 is also largely independent of myosin II; however, their adhesions are small and do not show retrograde fluxing suggesting other intrinsic factors determine their migration differences.

Dataset Information

The membrane scaffold CD82 regulates cell adhesion by altering ?4 integrin stability and molecular density.

Publications

The membrane scaffold CD82 regulates cell adhesion by altering α4 integrin stability and molecular density.

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