N-Glycosylation of integrin α5 acts as a switch for EGFR-mediated complex formation of integrin α5β1 to α6β4

N-Glycosylation of integrin alpha 5 beta 1 is involved in multiple cell behaviors. We previously reported that the N-glycosylations of the calf domain on integrin alpha 5 (S3-5,10-14) are essential for its inhibitory effect on EGFR signaling in regulating cell proliferation. However, the importance of the individual N-glycosylation and the underlying mechanisms of inhibition remain unclear. Here, we characterize the S3-5,10-14 mutants in detail and found that the N-glycosylation of site-11 (Asn712) is key for cell growth. The restoration of site-11, unlike the other individual sites, significantly suppressed cell growth and EGFR signaling in a manner that was similar to that of wild-type (WT). Mechanistically, this N-glycosylation inhibited the response abilities upon EGF stimulation and EGFR dimerization. Interestingly, we found this N-glycosylation controlled the EGFR complex formation with integrin alpha 5 beta 1 or alpha 6 beta 4; i.e., the loss of site-11 switched EGFR-alpha 5 beta 1 to EGFR-alpha 6 beta 4, which is well known to promote cellular signaling for cell growth. Moreover, the site-11 N-glycan exhibited a more branching structure compared with other sites, which may be required for EGFR-alpha 5 beta 1 formation. Taken together, these data clearly demonstrate that the site-11 N-glycosylation on a5 is most important for its inhibitory effect on EGFR signaling, which may provide a novel regulatory mechanism for crosstalks between integrins and EGFR.