Mystique is a new insulin-like growth factor-I-regulated PDZ-LIM domain protein that promotes cell attachment and migration and suppresses Anchorage-independent growth.
By comparing differential gene expression in the insulin-like growth factor (IGF)-IR null cell fibroblast cell line (R- cells) with cells overexpressing the IGF-IR (R+ cells), we identified the Mystique gene expressed as alternatively spliced variants. The human homologue of Mystique is located on chromosome 8p21.2 and encodes a PDZ LIM domain protein (PDLIM2). GFP-Mystique was colocalized at cytoskeleton focal contacts with alpha-actinin and beta1-integrin. Only one isoform of endogenous human Mystique protein, Mystique 2, was detected in cell lines. Mystique 2 was more abundant in nontransformed MCF10A breast epithelial cells than in MCF-7 breast carcinoma cells and was induced by IGF-I and cell adhesion. Overexpression of Mystique 2 in MCF-7 cells suppressed colony formation in soft agarose and enhanced cell adhesion to collagen and fibronectin. Point mutation of either the PDZ or LIM domain was sufficient to reverse suppression of colony formation, but mutation of the PDZ domain alone was sufficient to abolish enhanced adhesion. Knockdown of Mystique 2 with small interfering RNA abrogated both adhesion and migration in MCF10A and MCF-7 cells. The data indicate that Mystique is an IGF-IR-regulated adapter protein located at the actin cytoskeleton that is necessary for the migratory capacity of epithelial cells.
Loughran
Gary
G
Cell Biology Laboratory, Department of Biochemistry, BioSciences Institute, National University of Ireland, Cork, Ireland.
Healy
Nollaig C
NC
Kiely
Patrick A
PA
Huigsloot
Merei
M
Kedersha
Nancy L
NL
O'Connor
Rosemary
R
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic; D003094:Collagen / Q000378:metabolism; D003260:Contact Inhibition; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism; D060588:LIM Domain Proteins; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D000199:Actins; D003598:Cytoskeletal Proteins; D005353:Fibronectins; D019012:Integrin beta1; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; C502929:PDLIM2 protein, human; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D020033:Protein Isoforms; C496062:Pxn protein, mouse; C502928:mystique protein, mouse; D019000:Phosphotyrosine; D007334:Insulin-Like Growth Factor I; D003094:Collagen