Angora Mouse Mutation: Altered Hair Cycle, Follicular Dystrophy, Phenotypic Maintenance of Skin Grafts, and Changes in Keratin Expression

Abstract

Angora is an autosomal recessive mouse mutation caused by a deletion of approximately 2 kilobases in the fibroblast growth factor 5 (Fgf5) gene. Phenotypically, homozygous angora (Fgf5go/Fgf5go) mice have excessively long truncal hair and can be differentiated from heterozygous (+/Fgf5go) and wild-type (+/+) littermates by 21 days of age. Abnormal hair length is due to a prolongation of the anagen phase of the hair cycle of approximately 3 days. In addition, widely scattered hair follicles produce structurally defective hair shafts that twist within the follicle, presumably causing secondary hyperplasia of the outer root sheath and epidermis adjacent to the follicle. These follicular abnormalities were accentuated by immunohistochemical detection of mouse specific keratin 6, a nonspecific marker of epidermal hyperplasia. These abnormalities could be identified from birth throughout life in angora mice genotyped by polymerase chain reaction techniques. Moreover, the long truncal hair phenotype was maintained in skin grafted onto C.B-17/Sz-scid/scid mice that had normal pelage hairs and hair cycles, suggesting that circulating or diffusible humoral factors regulating the mouse hair cycle are not involved in this mutation. The angora mutation provides another useful mouse model for studying the hair cycle and its modulation.

A p38 inhibitor allows to dissociate differentiation and apoptotic processes triggered upon LIF withdrawal in mouse embryonic stem cells

“…The fgf-4 gene, which encodes a factor involved in different processes, like the propagation of cells from the ICM and trophoblasts of the embryo and limb patterning, 9,63,64 was reinduced in differentiated cells and behaved as an LIF-responsive gene. Also, the kinetics of expression of fgf-5 (a specific marker of primitive ectoderm and of some of its derivative), [65][66][67] and of brach (a mesoderm marker) mimicked the in vivo situation in early mouse embryos: the decrease of fgf-5 expression precedes the establishment of mesoderm that correlates with an increased expression of the brach gene. [68][69][70] The downregulation of the expression of various markers within the first 24 h of LIF withdrawal, which was not affected by the presence of the p38 inhibitor (PD169316), indicates that cells are committed to differentiate as soon as LIF was withdrawn, even in the presence of the inhibitor.…”

Development and evolution of the amniote integument: Current landscape and future horizon

“…The length of the integumentary appendage can also be modulated by varying the length of the growth phase. In Angora mice, for example, the long hairs are the result of an anagen phase that is a couple of days longer than normal (Sundberg et al, 1997). Similar changes may occur in the pelage of some hares that have longer hairs in winter, but shorter ones in summer.…”

Identification de mutations à l’origine de différents phénotypes chez les ânes

“…De nombreux articles mettent en évidence l'association entre le phénotype angora et des mutations du gène FGF5 (fibroblast growth factor 5) comme chez la souris où est montrée une délétion de 2 kb (Hébert et al 1994;Sundberg et al 1997;Mizuno et al 2011;), chez le chien où une mutation faux-sens est identifiée chez les animaux à poils longs (Housley & Venta, 2006;Dierks et al 2013) et chez le chat où quatre mutations dans FGF5 sont associées au phénotype poils longs Kehler et al 2007). …”

“…Les 10 % restants des baudets à poils longs pourraient être expliqués par l'association de cette délétion c.433_434delAT avec une autre mutation récessive : c.245G >A, comme cela est le cas dans notre échantillon. (Hébert et al 1994 ;Sundberg et al 1997 ;Housley & Venta, 2006 ;Kehler et al 2007 ;Mizuno et al 2011Dierks et al 2013).…”