Open AccessIdentification of Human Oral Keratinocyte Stem/Progenitor Cells by Neurotrophin Receptor p75 and the Role of Neurotrophin/p75 Signaling
Author(s) -
Nakamura Takahiro,
Endo Kenichi,
Kinoshita Shigeru
Publication year - 2007
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1634/stemcells.2006-0494
Subject(s) - biology , microbiology and biotechnology , keratinocyte , progenitor cell , stem cell , low affinity nerve growth factor receptor , neurotrophin , nerve growth factor , immunology , receptor , cell culture , biochemistry , genetics
This study was undertaken to determine whether human oral keratinocyte stem cells characteristically express higher levels of the low‐affinity neurotrophin receptor p75 and to elucidate the function of p75 in oral keratinocytes. Examination of their expression patterns and cell‐cycling status in vivo showed that p75 was exclusively expressed in the basal cell layer of both the tips of the papillae and the deep rete ridges. These immunostaining patterns suggest a cluster organization; most p75(+) cells did not actively cycle in vivo. Cell sorting showed that cells in the p75(+) subset were smaller and possessed higher in vitro proliferative capacity and clonal growth potential than the p75(−) subset. Clonal analysis revealed that holoclone‐type (stem cell compartment), meroclone‐type (intermediate compartment), and paraclone‐type (transient amplifying cell compartment) cells, previously identified in skin and the ocular surface, were present in human oral mucosal epithelium. Holoclone‐type cells showed stronger p75 expression at both the mRNA and protein level than did meroclone‐ and paraclone‐type cells. Among the several neurotrophins, nerve growth factor (NGF) and neurotrophin‐3 stimulated p75(+) oral keratinocyte cell proliferation, and only NGF protected them from apoptosis. Our in vivo and in vitro findings indicate that p75 is a potential marker of oral keratinocyte stem/progenitor cells and that some neurotrophin/p75 signaling affects cell growth and survival.