A novel mutation in Hr causes abnormal hair follicle morphogenesis in hairpoor mouse, an animal model for Marie Unna Hereditary Hypotrichosis.
Hairpoor mice (Hr(Hp)) were derived through N-ethyl-N-nitrosourea (ENU) mutagenesis. These mice display sparse and short hair in the Hr(Hp)/+ heterozygous state and complete baldness in the Hr(Hp)/Hr(Hp) homozygous state. This phenotype was irreversible and was inherited in an autosomal semidominant manner. Hair follicles (HFs) of Hr(Hp)/+ mice underwent normal cycling and appeared normal, although smaller than those of the wild-type mice. In contrast, HFs of Hr(Hp)/Hr(Hp) mice became cyst-like structures by postnatal day (P) 21. The number and length of vibrissae decreased in a dose-dependent manner as the number of mutant alleles increased. A positional candidate gene approach was used to identify the gene responsible for the hairpoor phenotype. Genetic linkage analysis determined that the hairpoor locus is 2 cm from D14Mit34 on chromosome 14. Sequence analysis of the exons of the candidate gene hairless revealed a T-to-A transversion mutation at nucleotide position 403 (exon 2), presumably resulting in abolishment of an upstream open reading frame (uORF). In addition, we also found that the near-naked mouse (Hr(N)), a spontaneously arising mutant, harbors a A402G transition in its genome. Both mutations were in the uATG codon of the second uORF in the 5' UTR and corresponded to the mutations identified in Marie Unna Hereditary Hypotrichosis (MUHH) patients. In the present study we describe the phenotype, histological morphology, and molecular etiology of an animal model of MUHH, the hairpoor mouse.
Baek
In Cheol
IC
Research Institute of Molecular Genetics, Catholic Research Institutes of Medical Science, Department of Biomedical Sciences, The Catholic University of Korea, Seoul, Korea.
Kim
Jeong Ki
JK
Cho
Kyu-Hyuk
KH
Cha
Dal-Sun
DS
Cho
Jae-Woo
JW
Park
Jong Keun
JK
Song
Chang-Woo
CW
Yoon
Sungjoo Kim
SK
D000818:Animals; D001483:Base Sequence; D004195:Disease Models, Animal; D018859:Hair Follicle / Q000002:abnormalities / Q000254:growth & development*; D006801:Humans; D007039:Hypotrichosis / Q000151:congenital* / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008812:Mice, Hairless; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009154:Mutation; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D014157:Transcription Factors; C088661:hr protein, mouse