Signals that initiate, augment, and provide directionality for human keratinocyte motility.
Human keratinocytes (HK) migration plays a critical role in the re-epithelialization of acute skin wounds. Although extracellular matrices (ECM) and growth factors (GF) are the two major pro-motility signals, their functional relationship remains unclear. We investigated how ECM and GF regulate HK motility under defined conditions: (1) in the absence of GF and ECM and (2) with or without GF with cells apposed to a known pro-motility ECM. Our results show that HK migrate on selected ECM even in the total absence of GF. This suggests that certain ECM alone are able to "initiate" HK migration. Unlike ECM, however, GF alone cannot initiate HK migration. HK cannot properly migrate when plated in the presence of GF, regardless of the concentration, without an ECM substratum. The role of GF, instead, is to augment ECM-initiated motility and provide directionality. To gain insights into the mechanism of action by ECM and GF, we compared, side-by-side, the roles of three major mitogen-activated protein kinase cascades, extracellular-signal-regulated kinase (ERK)1/2, p38, and c-Jun N-terminal kinase (JNK). Our data show that ERK1/2 is involved in mediating collagen's initiation signal and GF's augmentation signal. p38 is specific for GF's augmentation signal. JNK is uninvolved in HK motility. Constitutively activated p38 and ERK1/2 alone could not initiate HK migration. Co-expression of both constitutively activated p38 and ERK1/2, however, could partially mimic the pro-motility effects of collagen and GF. This study reveals for the first time the specific functions of ECM and GF in cell motility.
Li
Wei
W
The Department of Medicine, Division of Dermatology and the Norris Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California, USA. wli@usc.edu
Henry
Ginard
G
Fan
Jianhua
J
Bandyopadhyay
Balaji
B
Pang
Katie
K
Garner
Warren
W
Chen
Mei
M
Woodley
David T
DT
D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D022001:Focal Adhesions / Q000502:physiology; D006133:Growth Substances / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D014945:Wound Healing / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases
D006133:Growth Substances; D003094:Collagen; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases