Chromosomal localization of acidic and basic keratin genes of the domestic dog

Our laboratories are interested in characterizing genes involved in the myriad of heritable diseases affecting the domestic dog, Canis lupus familiaris, and in development of detailed genetic and physical maps of the canine genome. Included in these efforts is examination of conservation of the genetic organization, structure, and function of gene families involved in diseases of the canine skin, skeleton, and eye. To that end, study of the highly conserved keratin gene family was undertaken. Keratins belong to the superfamily of intermediate filaments and are the major structural proteins of the epidermis, hair, and nail. The keratins are highly conserved throughout vertebrate evolution both at the DNA and amino acid sequence levels. Mutations in genes encoding epithelial keratins are known to cause various diseases in humans, and similar histopathological presentations have been reported in the dog. The keratins are divided into two groups, type I (acidic) and type II (basic). In the human, the genes encoding the acidic and basic keratins are clustered on Chrs 17 and 12, respectively. The same genetic arrangement is seen in the mouse with the acidic and basic keratin gene clusters found on Chrs 11 and 15, respectively. Reported here are the chromosomal localization of acidic and basic canine keratin genes as well as supportive sequence data. Fluorescence in situ hybridization (FISH) experiments with clones isolated from a canine genomic library suggest that the acidic keratin gene cluster resides on CFA9 and the basic keratin gene cluster is located on CFA27.