EGF-induced MAPK signaling inhibits hemidesmosome formation through phosphorylation of the integrin {beta}4.
Migration of keratinocytes requires a regulated and dynamic turnover of hemidesmosomes (HDs). We and others have previously identified three serine residues on the integrin β4 cytoplasmic domain that play a critical role in the regulation of HD disassembly. In this study we show that only two of these residues (Ser-1356 and Ser-1364) are phosphorylated in keratinocytes after stimulation with either PMA or EGF. Furthermore, in direct contrast to previous studies performed in vitro, we found that the PMA- and EGF-stimulated phosphorylation of β4 is not mediated by PKC, but by ERK1/2 and its downstream effector kinase p90RSK1/2. EGF-stimulated phosphorylation of β4 increased keratinocyte migration, and reduced the number of stable HDs. Furthermore, mutation of the two serines in β4 to phospho-mimicking aspartic acid decreased its interaction with the cytoskeletal linker protein plectin, as well as the strength of α6β4-mediated adhesion to laminin-332. During mitotic cell rounding, when the overall cell-substrate area is decreased and the number of HDs is reduced, β4 was only phosphorylated on Ser-1356 by a distinct, yet unidentified, kinase. Collectively, these data demonstrate an important role of β4 phosphorylation on residues Ser-1356 and Ser-1364 in the formation and/or stability of HDs.
Frijns
Evelyne
E
Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
Sachs
Norman
N
Kreft
Maaike
M
Wilhelmsen
Kevin
K
Sonnenberg
Arnoud
A
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002453:Cell Cycle; D002460:Cell Line; D002522:Chlorocebus aethiops; D015536:Down-Regulation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D022002:Hemidesmosomes / Q000201:enzymology / Q000378:metabolism*; D039663:Integrin beta4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation
D039663:Integrin beta4; D004815:Epidermal Growth Factor