Induction of the hair growth phase in postnatal mice by localized transient expression of Sonic hedgehog
Noboru Sato, … , Philip L. Leopold, Ronald G. Crystal
Noboru Sato, … , Philip L. Leopold, Ronald G. Crystal
Published October 1, 1999
Citation Information: J Clin Invest. 1999;104(7):855-864. https://doi.org/10.1172/JCI7691.
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Article

Induction of the hair growth phase in postnatal mice by localized transient expression of Sonic hedgehog

Abstract

Hair follicles form in prenatal skin and mature in the postnatal period, establishing a growth cycle in 3 phases: telogen (resting), anagen (growth), and catagen (regression). Based on the knowledge that Sonic hedgehog (Shh) expression is necessary for the embryonic development of hair follicles, and that anagen in the postnatal cycling follicle has morphologic similarities to the epithelial invagination process in embryonic skin, we hypothesized that localized, but transient, enhanced expression of the Shh gene in postnatal skin would accelerate initiation of anagen in the hair follicle cycle, with concomitant accelerated hair growth. To assess this concept, an E1– adenovirus vector, AdShh, was used to transfer the murine Shh cDNA to skin of postnatal day 19 C57BL/6 mice. The treated skin showed increased mRNA expression of Shh, Patched (the Shh receptor), and Gli1 (a transcription factor in the Shh pathway). In mice receiving AdShh, but not in controls, acceleration into anagen was evident, since hair follicle size and melanogenesis increased and the hair-specific keratin ghHb-1 and the melanin synthesis–related tyrosinase mRNAs accumulated. Finally, C57BL/6 mice showed marked acceleration of the onset of new hair growth in the region of AdShh administration to skin 2 weeks after treatment, but not in control vector–treated or untreated areas. After 6 months, AdShh-treated skin showed normal hair and normal skin morphology. Together, these observations are consistent with the concept that upregulation of Shh activity in postnatal skin functions as a biologic switch that induces resting hair follicles to enter anagen with consequent hair growth.

Authors

Noboru Sato, Philip L. Leopold, Ronald G. Crystal

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Figure 1

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Functional expression of Shh by administration of AdShh in vitro and in ...
Functional expression of Shh by administration of AdShh in vitro and in vivo in postnatal day 19 C57BL/6 mice. (a) Shh mRNA after in vitro infection of A549 epithelial cells with AdShh. A549 cells (106) were infected (20 moi) with the AdNull control vector or AdShh. After 2 days, RNA was analyzed by Northern blot with a 32P-labeled Shh cDNA probe. Uninfected cells (naive) and AdNull-infected cells were negative, whereas AdShh-infected cells contained a transcript of approximately 3.0 kb corresponding to the vector-encoded Shh transgene. Equal RNA loading was confirmed by analysis of GAPDH mRNA. (b) Shh protein expressed in vitro. Protein from A549 cells infected with AdNull or AdShh as described in a was analyzed by immunoblot for Shh protein. AdShh-infected, but not naive or AdNull-infected, A549 cells showed a 19-kDa immunoreactive band with anti-Shh. Equal protein loading was confirmed by Coomassie blue staining of an identically loaded gel (not shown). (c) Time course demonstrating expression of Shh, Ptc, and Gli1 mRNA in vivo. Dorsal skin was collected from naive C57BL/6 mice or C57BL/6 mice at postnatal days 19, 22, 24, 26, and 33 after intradermal injection on day 19 with AdNull or AdShh (108 PFU for either vector). Skin was analyzed for Shh, Ptc, or Gli1 mRNA by Northern analysis on experimental days 0, 3, 5, 7, and 14. Expression of the 3.0-kb mRNA vector-encoded transcript (upper arrow) and the 2.6-kb endogenous Shh transcript (lower arrows) was detected in AdShh-injected mice, but the vector-derived transcript temporally preceded the endogenous transcript. Marked upregulation of Ptc and Gli1 gene expression was detected in AdShh-injected mice on experimental days 3 and 5, when low levels of expression of these genes were seen in naive and AdNull-treated mice. Equal RNA loading was confirmed by analysis of GAPDH mRNA.