Ectopic expression of c-Myc in the skin affects the hair growth cycle and causes an enlargement of the sebaceous gland.
BACKGROUND
The hair follicle continually undergoes dynamic remodelling in a cyclical manner involving tightly coordinated patterns of cell proliferation, differentiation and apoptosis. The oncoprotein c-Myc is a key regulator of these events in epidermal keratinocytes, but its importance in the hair growth cycle has not previously been determined.


OBJECTIVE
To determine the role of c-Myc in the hair growth cycle.


METHODS
We characterized the hair follicle phenotype of transgenic mice that permit expression of a switchable form of c-Myc (c-Myc-ER) in the suprabasal epithelial layers of the epidermis and hair follicle.


RESULTS
c-Myc activation increased epithelial cell proliferation in the outer root sheath and distal hair follicle, without any substantial alteration in levels of apoptosis. Moreover, chronic c-Myc activation resulted in marked desynchronization of the murine hair growth cycle, uncoupling of hair cycle-related skin thickness and enlargement of the sebaceous gland.


CONCLUSIONS
These data implicate c-Myc in the control of hair growth cycling and hair cycle-related epidermal and sebaceous gland homeostasis. We suggest that c-Myc may be activating follicular stem cells either directly or indirectly and that this has important implications for control of the 'hair cycle clock', hair growth and epidermal maintenance.
Bull
J J
JJ
Centre for Cutaneous Research, Barts and The London School of Medicine and Dentistry, Queen Mary College, London E1 2AT, UK.
Pelengaris
S
S
Hendrix
S
S
Chronnell
C M T
CM
Khan
M
M
Philpott
M P
MP
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D049109:Cell Proliferation / Q000187:drug effects; D004817:Epidermis / Q000473:pathology; D004965:Estrogen Antagonists / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D016259:Genes, myc; D006197:Hair / Q000254:growth & development*; D018859:Hair Follicle / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D012535:Scalp; D012627:Sebaceous Glands / Q000473:pathology*; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology
D015415:Biomarkers; D004965:Estrogen Antagonists; D019394:Ki-67 Antigen; D016271:Proto-Oncogene Proteins c-myc; D013629:Tamoxifen; C016601:afimoxifene