Dynamic membrane-cytoskeletal interactions: specific association of integrin and talin arises in vivo after phorbol ester treatment of peripheral blood lymphocytes.

Abstract

Members of the family of transmembrane integral membrane proteins called integrins have been implicated in forming attachments to actin microfflaments of the cytoskeleton. These attachments are thought to involve one or more intervening peripheral membrane proteins linked to integrin. To detect such possible linkages in vivo, the integrin molecules on the surfaces of intact chicken peripheral blood lymphocytes were collected into caps by cross-lnkin with specific antibodies, and the capped cells were examined by double immunofluorescence to determine whether particular cytoskeletal proteins were co-collected with the integrin. With resting lymphocytes, the capping of integrin did not result in any detectable redistribution of either talin, vinculin, or a-actinin inside the cells. However, if the capping was carried out upon the addition of phorbol 12-myristate 13-acetate (PMA) to the cells, then talin, but not vinculin or a-actinin, was found associated with the integrin caps. PMA is known to activate protein kinase C. These results suggest that after, but not before, PMA stimulation of intact cells, talin becomes linked either directly or indirectly with integrin, reflecting the formation of a membrane-cytoskeletal association that is metabolically regulated.Connections between the plasma membrane and the cytoskeleton play important roles in many cellular phenomena, including cell-cell interactions, cell motility, and signal transmission across membranes. The basis for understanding the molecular nature of membrane-cytoskeletal connections was provided by the recognition of the existence and properties of two distinct classes of membrane proteins, integral and peripheral (1). It was proposed that specific peripheral proteins in the cytoplasm bind to the exposed hydrophilic domains of particular membrane integral proteins in the formation of each type of membrane-cytoskeletal attachment (1-3). However, except for erythrocytes, the detailed molecular composition and structure of membrane-cytoskeletal connections in eukaryotic cells are not known.The associations of membranes with the actin microfilaments of the cytoskeleton have received much study, and in recent years a considerable number of peripheral and integral proteins have been proposed to participate in the associations (for review, see ref. 4). In particular, a family of integral membrane proteins called integrins (for reviews, see refs. 5 and 6) have been implicated as providing cytoplasmic membrane sites for the linkage of membranes to microfilaments. Immunofluorescence microscopic experiments have shown a close correspondence in the cell-surface distributions of integrin with actin microfilaments lying under the membrane (7-9). In addition, the cytoskeletal proteins talin (10, 11), vinculin (12), and a-actinin (13) have been localized by immunocytochemical methods at various sites of attachment of actin microfilaments to membranes, and each has therefore been considered a potential linker molecule between the membrane and the microfilaments (...

Dual role of the actin cytoskeleton in regulating cell adhesion mediated by the integrin lymphocyte function-associated molecule-1.

“…In addition, adhesion of these cells can be increased by PMA or the activating mAb KIM185, demonstrating that besides clustering of LFA-1 (avidity), affinity changes in the LFA-1 molecule (active conformation) are still required for strong binding to ICAM-1. These findings, along with data that integrins can associate with cytoskeletal components (a-actinin and talin), in particular through the 13-chain (Burn et al, 1988;Pavalko and LaRoche, 1993), led us to hypothesize that certain cytoskeletal proteins are essential to maintain LFA-1 in a high-avidity state on these cells. The observation that cytochalasin D, which inhibits actin polymerization, blocks the adhesion (in the absence of an activator of LFA-1) of the L cell, BLM transfectants, and IL-2/PHA-activated PBLs supports this hypothesis and demonstrates that this phenomenon is not leukocyte restricted.…”

“…Thus, when LFA-1 is expressed on either hematopoietic or nonhematopoietic cells, adhesion to ICAM-1 can be induced by alteration in avidity (clustering) or affinity (induced by PMA or KIM185), whereas both avidity and affinity alteration cooperate to induce maximal adhesion. The importance of the association of cytoskeletal components (a-actinin and talin) with the ,32-chain has been reported previously (Burn et al, 1988;Pavalko and LaRoche, 1993). However, it is not known whether association with the cytoskeleton is important in modulating the affinity, the distribution of LFA-1, or both.…”

“…Previous experiments have demonstrated that integrins can associate with cytoskeletal components (aactinin, talin) upon activation (Burn et al, 1988;Pavalko and LaRoche, 1993). Inhibitors such as cytochalasin B and D have been used to inhibit 132-and [31-mediated adhesion to their ligands (Rothlein and Springer, 1986;Haverstick et al, 1992;Pyszniak et al, 1994).…”

Identification of an Arg-Gly-Asp (RGD) cell adhesion site in human immunodeficiency virus type 1 transactivation protein, tat.

“…The alpha and beta int¢grin subunits both contain a small cytoplasmic domain which can interact with the cytoskeleton matrix (10,11,37). Integrin-mediated binding to vitronectin and other matrix proteins is typically associated with integrin aggregation and cytoskeletal reorganization of microfilaments and microfilament-associated proteins, such as talin and vinculin (10,11). l-,s myoblasts bound to vitronectin were spread and displayed numerous projections typical of integrin-mediated binding to matrix proteins.…”

TAGLN2 regulates T cell activation by stabilizing the actin cytoskeleton at the immunological synapse

“…Previous experiments have demonstrated that the actin cytoskeleton can regulate integrin-mediated T cell adhesion (Burn et al, 1988). Inhibitors such as cytochalasin B and D (Cyt D) have been used to inhibit 2-and 1-mediated adhesion to their ligands (Rothlein and Springer, 1986).…”