Modulation of α-actinin levels affects cell motility and confers tumorigenicity on 3T3 cells

Abstract

alpha-Actinin is an abundant actin crosslinking protein, also localized at adherens type junctions. In adhesion plaques, alpha-actinin can link the actin filaments to integrin via vinculin and talin, or directly by binding to the cytoplasmic domain of beta 1-integrin. The expression of alpha-actinin is rapidly elevated in growth-activated quiescent cells, and is reduced in SV40-transformed 3T3 cells and various differentiating cell types (reviewed by Gluck, U., Kwiatkowski, D. J. and Ben-Ze'ev, A. Proc. Nat. Acad. Sci. USA 90, 383–387, 1993). To study the effect of changes in alpha-actinin levels on cell behavior, alpha-actinin expression was elevated in 3T3 cells by transfection with a full-length human nonmuscle alpha-actinin cDNA. To suppress alpha-actinin levels, 3T3 cells were transfected with an antisense alpha-actinin cDNA construct. Cells overexpressing alpha-actinin by 40–60% displayed a significant reduction in cell motility, as demonstrated by their slower locomotion into an artificial wound, and by forming shorter phagokinetic tracks on colloidal gold-coated substrata. 3T3 cells in which the expression of alpha-actinin was reduced to 25–60% of control levels, after antisense alpha-actinin transfection, had an increased cell motility. Moreover, such alpha-actinin-deficient 3T3 cells formed tumors upon injection into nude mice. The results demonstrate that modulations in alpha-actinin expression can affect, in a major way, the motile and tumorigenic properties of cells, and support the view that decreased alpha-actinin expression could be a common regulatory pathway to malignant transformation of 3T3 cells.

Interaction of Zonula Occludens-1 (ZO-1) with α-Actinin-4: Application of Functional Proteomics for Identification of PDZ Domain-Associated Proteins

“…Assembly and disassembly of R-actinin-4 and associated proteins at adherens junctions was shown to play an important role in either stabilizing cell adhesion and suppressing cell motility or promoting loss of adherens junctions leading to increased rates of metastasis. [45][46][47] Further, up-regulation R-actinin-4 was correlated with increased cell motility, invasive growth, and lymph-node metastasis in colorectal cancer 48 and was a prognostic predictor in nonsmall cell lung cancers. 49 Greatly elevated levels of cytoplasmic R-actinin-4 was found in invasive phenotypes of breast cancer with high metastatic potential and poor survival rates.…”

“…In some cells, they also interact with the intercellular domains of ICAM-1, L-selectin, and β2 integrins. − Given its multifunctional roles in relation to transmembrane proteins and cytoskeletal networks, α-actinin-4 has received considerable attention as a target for regulation by signaling pathways, particularly in the areas of metastasis and cancer. Assembly and disassembly of α-actinin-4 and associated proteins at adherens junctions was shown to play an important role in either stabilizing cell adhesion and suppressing cell motility or promoting loss of adherens junctions leading to increased rates of metastasis. − Further, up-regulation α-actinin-4 was correlated with increased cell motility, invasive growth, and lymph-node metastasis in colorectal cancer and was a prognostic predictor in nonsmall cell lung cancers…”

Porous Substrates Promote Endothelial Migration at the Expense of Fibronectin Fibrillogenesis

“…One of the better-understood cell–substrate interactions is the anchoring of cells via focal adhesions (FAs), which enables the cells to sense their microenvironment during migration and tissue barrier formation and remodeling. , FA formation initiates as the integrins on the cell surface bind to extracellular matrix (ECM) ligands . As integrins cluster at the cell–ECM contact, the closely spaced cytoplasmic portions of the integrins serve as a recruiting platform to host the docking and interaction of proteins that either provide linkage to the actin cytoskeleton or signal the cells to proliferate, survive, or migrate. − Because FAs enable the force coupling between the cell and the ECM, the coordinated assembly and disassembly of FAs can sometimes influence cell motility and directionality …”

Domain analysis of supervillin, an F-actin bundling plasma membrane protein with functional nuclear localization signals

“…The disruption of focal adhesion plaque structure by supervillin may correlate with the observation that the intracellular localizations of supervillin and alpha-actinin appear to be mutually exclusive. The actin bundling and membrane association activities of alpha-actinin-1 are important for stress fiber integrity, for the formation and extent of focal adhesion plaques, and for the adhesion of cells to each other and to the substrate (Glück and Ben-Ze'ev, 1994;Glück et al, 1993;Knudsen et al, 1995;Pavalko and Burridge, 1991;Schultheiss et al, 1992). While two or more actin bundling proteins apparently cooperate to form actin filament bundles in intestinal brush border microvilli (reviewed by Bretscher, 1991;Fath and Burgess, 1995;Heintzelman and Mooseker, 1992;Louvard et al, 1992), Drosophila neurosensory bristles (Tilney et al, 1995;Wulfkuhle et al, 1998), stereocilia (reviewed by Tilney et al, 1992), and Drosophila nurse cell ring canals (reviewed by Robinson and Cooley, 1997), non-synergistic pairs of actin bundling proteins also are known.…”