Targeted deletion of the integrin beta4 signaling domain suppresses laminin-5-dependent nuclear entry of mitogen-activated protein kinases and NF-kappaB, causing defects in epidermal growth and migration.
The alpha6beta4 integrin-a laminin-5 receptor-mediates assembly of hemidesmosomes and recruitment of Shc and phosphoinositide 3-kinase through the unique cytoplasmic extension of beta4. Mice carrying a targeted deletion of the signaling domain of beta4 develop normally and do not display signs of skin fragility. The epidermis of these mice contains well-structured hemidesmosomes and adheres stably to the basement membrane. However, it is hypoplastic due to reduced proliferation of basal keratinocytes and undergoes wound repair at a reduced rate. Keratinocytes from beta4 mutant mice undergo extensive spreading but fail to proliferate and migrate in response to epidermal growth factor (EGF) on laminin-5. EGF causes significant phosphorylation of extracellular signal-regulated kinase (ERK) and Jun N-terminal protein kinase (JNK) and phosphorylation and degradation of IkappaB in beta4 mutant cells adhering to laminin-5. Unexpectedly, however, ERK, JNK, and NF-kappaB remain in the cytoplasm in beta4 mutant cells on laminin-5, whereas they enter effectively into the nucleus in the same cells on fibronectin or in wild-type cells on both matrix proteins. Inhibitor studies indicate that alpha6beta4 promotes keratinocyte proliferation and migration through its effect on NF-kappaB and P-JNK. These findings provide evidence that beta4 signaling promotes epidermal growth and wound healing through a previously unrecognized effect on nuclear translocation of NF-kappaB and mitogen-activated protein kinases.
Cell Biology Program, Memorial Sloan-Kettering Cancer Center, Box 216, 1275 York Avenue, New York, New York 10021, USA.
Sotiris N
SN
Nikolopoulos
Pamela
P
Blaikie
Toshiaki
T
Yoshioka
Wenjun
W
Guo
Claudia
C
Puri
Carlo
C
Tacchetti
Filippo G
FG
Giancotti
D021581:Active Transport, Cell Nucleus; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000037:antagonists & inhibitors / Q000502:physiology*; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism*; D000078404:Epidermal Cells; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004817:Epidermis / Q000254:growth & development*; D017353:Gene Deletion; D018390:Gene Targeting; D039161:Integrin alpha6beta4 / Q000235:genetics / Q000502:physiology*; D039663:Integrin beta4 / Q000235:genetics; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D016328:NF-kappa B / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D014945:Wound Healing / Q000235:genetics / Q000502:physiology; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D004815:Epidermal Growth Factor; D039161:Integrin alpha6beta4; D039663:Integrin beta4; D048031:JNK Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D000097794:Kalinin