Brick1 is an essential regulator of actin cytoskeleton required for embryonic development and cell transformation.
Brick1 (Brk1) is the less-studied component of the Wave/Scar pathway involved in the branched nucleation of actin fibers. The clinical relevance of Brk1 is emphasized by correlative data showing that Von Hippel-Lindau (VHL) patients that also lose the BRK1 gene are protected against the development of tumors. This contrasts with recent evidence suggesting that the Wave complex may function as an invasion suppressor in epithelial cancers. Here, we show that the downregulation of Brk1 results in abnormal actin stress fiber formation and vinculin distribution and loss of Arp2/3 and Wave proteins at the cellular protrusions. Brk1 is required for cell proliferation and cell transformation by oncogenes. In addition, Brk1 downregulation results in defective directional migration and invasive growth in renal cell carcinoma cells as well as in other tumor cell types. Finally, genetic ablation of Brk1 results in dramatic defects in embryo compaction and development, suggesting an essential role for this protein in actin dynamics. Thus, genetic loss or inhibition of BRK1 is likely to be protective against tumor development due to proliferation and motility defects in affected cells.
Escobar
Beatriz
B
Cell Division and Cancer Group, Confocal Microscopy and Cytometry Unit, Spanish Nacional Cancer Research Center (CNIO), Madrid, Spain.
de Cárcer
Guillermo
G
Fernández-Miranda
Gonzalo
G
Cascón
Alberto
A
Bravo-Cordero
José J
JJ
Montoya
María C
MC
Robledo
Mercedes
M
Cañamero
Marta
M
Malumbres
Marcos
M
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism*; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000196:embryology / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000556:secondary; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D016513:Mice, SCID; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000199:Actins; C519848:BRK1 protein, human; C555657:Brick1 protein, mouse; D003598:Cytoskeletal Proteins