Rhamm-/- fibroblasts are defective in CD44-mediated ERK1,2 motogenic signaling, leading to defective skin wound repair.
Rhamm (receptor for hyaluronan-mediated motility) is an hyaluronan binding protein with limited expression in normal tissues and high expression in advanced cancers. To understand its physiological functions and identify the molecular mechanisms underlying these functions, we created mice with a genetic deletion of Rhamm. We show that Rhamm(-/-) fibroblasts fail to resurface scratch wounds >3 mm or invade hyaluronan-supplemented collagen gels in culture. We identify a requirement for Rhamm in the localization of CD44 to the cell surface, formation of CD44-ERK1,2 (extracellular-regulated kinase 1,2) complexes, and activation/subcellular targeting of ERK1,2 to the cell nucleus. We also show that cell surface Rhamm, restricted to the extracellular compartment by linking recombinant protein to beads, and expression of mutant active mitogen-activated kinase kinase 1 (Mek1) are sufficient to rescue aberrant signaling through CD44-ERK1,2 complexes in Rh(-/-) fibroblasts. ERK1,2 activation and fibroblast migration/differentiation is also defective during repair of Rh(-/-) excisional skin wounds and results in aberrant granulation tissue in vivo. These results identify Rhamm as an essential regulator of CD44-ERK1,2 fibroblast motogenic signaling required for wound repair.
Tolg
Cornelia
C
London Regional Cancer Program, London, Ontario N6A 4L6, Canada.
Hamilton
Sara R
SR
Nakrieko
Kerry-Ann
KA
Kooshesh
Fatemeh
F
Walton
Paul
P
McCarthy
James B
JB
Bissell
Mina J
MJ
Turley
Eva A
EA
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006720:Homozygote; D018960:Hyaluronan Receptors / Q000235:genetics / Q000502:physiology*; D006820:Hyaluronic Acid / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D015398:Signal Transduction; D012867:Skin / Q000293:injuries* / Q000378:metabolism; D014945:Wound Healing
D016326:Extracellular Matrix Proteins; D018960:Hyaluronan Receptors; C098946:hyaluronan-mediated motility receptor; D006820:Hyaluronic Acid; D003094:Collagen; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3