Hair cycle control by leptin as a new anagen inducer.
Our purpose is to clarify the physiological role of leptin in hair cycle as leptin reportedly causes activation of Stat3, which is indispensable for hair cycling. While hair follicles in dorsal skin of 5-week-old C57/BL6 mice had progressed to late anagen phase, those in dorsal skin of 5-week-old leptin receptor deficient db/db mice remained in the first telogen and later entered the anagen at postnatal day 40, indicating that deficiency in leptin receptor signalling delayed the second hair cycle progression. Next, we shaved dorsal hairs on wild-type mice at postnatal 7 weeks and injected skin with mouse leptin or a mock. After 20 days, although mock injection showed no effect, hair growth occurred around leptin injection area. Human leptin fragment (aa22-56) had similar effects. Although the hair cycle of ob/ob mice was similar to that of wild-type mice, injection of mouse leptin on ob/ob mice at postnatal 7 weeks induced anagen transition. Immunohistochemically, leptin is expressed in hair follicles from catagen to early anagen in wild-type mice, suggesting that leptin is an anagen inducer in vivo. Phosphorylation of Erk, Jak2 and Stat3 in human keratinocytes was stimulated by leptin and leptin fragment. In addition, RT-PCR and ELISA showed that the production of leptin by human dermal papilla cells increased under hypoxic condition, suggesting that hypoxia in catagen/telogen phase promotes leptin production, preparing for entry into the next anagen. In conclusion, leptin, a well-known adipokine, acts as an anagen inducer and represents a new player in hair biology.
Department of Regenerative Dermatology, Osaka University School of Medicine, Osaka, Japan.
Yasuyuki
Y
Sumikawa
Shigeki
S
Inui
Takeshi
T
Nakajima
Satoshi
S
Itami
D000818:Animals; D002478:Cells, Cultured; D006197:Hair / Q000254:growth & development*; D018859:Hair Follicle / Q000187:drug effects / Q000502:physiology; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D020738:Leptin / Q000008:administration & dosage / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008820:Mice, Obese; D010446:Peptide Fragments / Q000008:administration & dosage; D054411:Receptors, Leptin / Q000172:deficiency / Q000235:genetics; D011994:Recombinant Proteins / Q000008:administration & dosage; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction
D020738:Leptin; D010446:Peptide Fragments; D054411:Receptors, Leptin; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; C515447:leptin receptor, mouse
Erk; Jak2; Stat3; hair cycle; leptin