Fibronectin controls cap-dependent translation through beta1 integrin and eukaryotic initiation factors 4 and 2 coordinated pathways.
Fibronectin (FN) is a major matrix protein involved in multiple processes. Little is known about how adhesion to FN affects the translational machinery. We show that in fibroblasts adhesion to FN triggers translation through the coordinated regulation of eukaryotic initiation factors (eIFs) 4F and 2 and is impaired by blocking beta1 integrin engagement. FN-stimulated translation has unique properties: (i) it is highly sensitive to the inhibition of phosphatidylinositol 3-kinase (PI3K), but not to the inhibition of mammalian target of rapamycin, downstream of PI3K; (ii) there is no synergy between serum-stimulated translation and FN-dependent translation; (iii) FN-dependent translation, unlike growth factor-stimulated translation, does not lead to increased translocation of 5' terminal oligopyrimidine tract mRNAs to polysomes; and (iv) cells devoid of attachment to matrix show an impairment of initiation of translation accompanied by phosphorylation of eIF2alpha, which cannot be reverted by active PI3K. These findings indicate that integrins may recruit the translational machinery in a unique way and that FN-dependent translation cannot be blocked by mammalian target of rapamycin inhibition.
Gorrini
Chiara
C
Molecular Histology Unit, San Raffaele Institute, 20132 Milan, Italy.
Loreni
Fabrizio
F
Gandin
Valentina
V
Sala
Leonardo A
LA
Sonenberg
Nahum
N
Marchisio
Pier Carlo
PC
Biffo
Stefano
S
D000818:Animals; D015152:Blotting, Northern; D002448:Cell Adhesion; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000737:chemistry; D006801:Humans; D015151:Immunoblotting; D019012:Integrin beta1 / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D010448:Peptide Initiation Factors / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011132:Polyribosomes / Q000737:chemistry; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D021381:Protein Transport; D011506:Proteins / Q000737:chemistry; D011743:Pyrimidines / Q000737:chemistry; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases; D014162:Transfection
D004791:Enzyme Inhibitors; D015852:Eukaryotic Initiation Factor-2; D005353:Fibronectins; D006160:Guanosine Triphosphate; D019012:Integrin beta1; D016023:Integrins; D010448:Peptide Initiation Factors; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D011506:Proteins; D011743:Pyrimidines; D012313:RNA; D012333:RNA, Messenger; D058570:TOR Serine-Threonine Kinases; C075833:eIF-4; C546842:MTOR protein, human; C546843:mTOR protein, mouse