title: The membrane scaffold CD82 regulates cell adhesion by altering α4 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 α4 integrin subunits. Our data demonstrate that CD82 overexpression increases the molecular density of α4 within membrane clusters, thereby increasing cellular adhesion. Furthermore, we find that the tight packing of α4 into membrane clusters depend on CD82 palmitoylation and the presence of α4 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.
authors.affiliation: Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Termini
authors.affiliation: Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131.
authors.forename: Maura L
authors.initials: ML
authors.lastname: Cotter
authors.affiliation: Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131.
authors.forename: Kristopher D
authors.initials: KD
authors.lastname: Marjon
authors.affiliation: Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131.
authors.forename: Tione
authors.initials: T
authors.lastname: Buranda
authors.affiliation: Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Lidke
authors.affiliation: Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 jgillette@salud.unm.edu.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Gillette
mesh_terms: D002448:Cell Adhesion / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D021982:Cell-Matrix Junctions / Q000378:metabolism; D022082:Cellular Structures / Q000378:metabolism; D004705:Endocytosis; D005353:Fibronectins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D039441:Integrin alpha4 / Q000096:biosynthesis / Q000378:metabolism*; D039041:Integrin alpha4beta1 / Q000096:biosynthesis / Q000378:metabolism*; D051861:Kangai-1 Protein / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D054878:Lipoylation; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000502:physiology
chemical_list: C497688:CD82 protein, human; D005353:Fibronectins; D039041:Integrin alpha4beta1; D051861:Kangai-1 Protein; D034741:RNA, Small Interfering; D039441:Integrin alpha4