RGD Reference Report - The hairless phenotype of the Hirosaki hairless rat is due to the deletion of an 80-kb genomic DNA containing five basic keratin genes. - Rat Genome Database

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The hairless phenotype of the Hirosaki hairless rat is due to the deletion of an 80-kb genomic DNA containing five basic keratin genes.

Authors: Nanashima, N  Akita, M  Yamada, T  Shimizu, T  Nakano, H  Fan, Y  Tsuchida, S 
Citation: Nanashima N, etal., J Biol Chem. 2008 Jun 13;283(24):16868-75. Epub 2008 Apr 16.
RGD ID: 2316553
Pubmed: PMID:18420582   (View Abstract at PubMed)
DOI: DOI:10.1074/jbc.M802539200   (Journal Full-text)

Most models of hereditary hypotrichosis are due to alterations in growth factors and transcription factors, and the examples of causative mutations in hair keratin genes are limited. The Hirosaki hairless rat (HHR) is a mutant strain spontaneously derived from Sprague-Dawley rats (SDRs). In this study, the locus of the responsible gene was examined by linkage analysis and mapped on chromosome 7q36. Because many basic keratin genes are clustered on 7q36, their expression was examined. Reverse transcription-PCR and genomic PCR indicated that the Kb21 (Krt81), -23 (Krt83), and -26 (Krt86) genes encoding basic hair keratins were not expressed and were deleted. Furthermore, 80-kb genomic DNA ranging from exon 9 of Kb25 (Krt85) to exon 9 of Krt2-25 was deleted. The breakpoints of these genes were within a 95-bp portion shared by the two genes, suggesting that deletion due to non-allelic homologous recombination occurred. Proteins identified as Kb21, Kb23, and Krt2-25 in SDR hairs by mass spectrometry were not detected in HHR. Instead, the product of a fusion gene became dominant in HHR. Because fusion occurred between the exons of the two genes with the same sequences, the product was identical to the wild-type Kb25 protein. By using immunohistochemistry, Kb21 was not detected in HHR hair follicles. Kb25 was expressed in the cortex in HHRs, whereas it was in the medulla in SDRs. This study clearly illustrates the importance of hair keratin genes in hair growth.



Phenotype Annotations    Click to see Annotation Detail View

Mammalian Phenotype

Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Krt83Ratabnormal hair growth  IAGP DNA:deletionRGD 
Krt87Ratabnormal hair growth  IAGP DNA:deletionRGD 
HHR/HatRathairless  IAGP  RGD 
Objects Annotated

Genes (Rattus norvegicus)
Krt83  (keratin 83)
Krt87  (keratin 87)

Strains
HHR/Hat  (Hirosaki hairless rat)


Additional Information