A keratinocyte hypermotility/growth-arrest response involving laminin 5 and p16INK4A activated in wound healing and senescence.
Keratinocytes become migratory to heal wounds, during early neoplastic invasion, and when undergoing telomere-unrelated senescence in culture. All three settings are associated with expression of the cell cycle inhibitor p16INK4A (p16) and of the basement membrane protein laminin 5 (LN5). We have investigated cause-and-effect relationships among laminin 5, p16, hypermotility, and growth arrest. Plating primary human keratinocytes on the gamma2 precursor form of laminin 5 (LN5') immediately induced directional hypermotility at approximately 125 microm/hour, followed by p16 expression and growth arrest. Cells deficient in p16 and either p14ARF or p53 became hypermotile in response to LN5' but did not arrest growth. Plating on LN5' triggered smad nuclear translocation, and all LN5' effects were blocked by a transforming growth factor (TGF) beta receptor I (TGFbetaRI) kinase inhibitor. In contrast, plating cells on collagen I triggered a TGFbetaRI kinase-independent hypermotility unaccompanied by smad translocation or growth arrest. Plating on control surfaces with TGFbeta induced hypermotility after a 1-day lag time and growth arrest by a p16-independent mechanism. Keratinocytes serially cultured with TGFbetaRI kinase inhibitor exhibited an extended lifespan, and immortalization was facilitated following transduction to express the catalytic subunit of telomerase (TERT). These results reveal fundamental features of a keratinocyte hyper-motility/growth-arrest response that is activated in wound healing, tumor suppression, and during serial culture.
Natarajan
Easwar
E
Department of Dermatology, Brigham and Women's Hospital and Harvard Skin Disease Research Center, Harvard Institutes of Medicine, Room 664, 77 Ave. Louis Pasteur, Boston, MA 02115, USA.
Omobono
John D
JD
Guo
Zongyou
Z
Hopkinson
Susan
S
Lazar
Alexander J F
AJ
Brenn
Thomas
T
Jones
Jonathan C
JC
Rheinwald
James G
JG
D015815:Cell Adhesion Molecules / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D002465:Cell Movement; D049109:Cell Proliferation; D016922:Cellular Senescence; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D005260:Female; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D008297:Male; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D014945:Wound Healing; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018125:Receptors, Transforming Growth Factor beta; D025803:Tumor Suppressor Protein p14ARF; D000097794:Kalinin