The genetics of Sleek: a possible regulatory mutation of the tabby-crinkled-downless syndrome

Molecular basis and genetics of hypohidrotic ectodermal dysplasias

Ectodermal dysplasia (ED) is a heterogeneous group of hereditary diseases of the skin and its appendages, which are characterized by impaired development and/or homeostasis of two or more ectoderm derivatives, including: hair, teeth, nails, sweat glands and their modifications (mammary glands, for instance). The overall prevalence of ectodermal dysplasia remains precisely unknown not only in Russia, but also in the world, nor is known the contribution of individual genes to its structure. This complicates the DNA diagnosis establishment of this disease due to the lack of an accurate diagnostic algorithm and a universal cost-effective method of analysis. To date, the most highly-researched genes involved in the development of anhydrous or hypohidrotic forms of ED are EDA, EDAR, EDARADD and WNT10A. The ectodysplasin A (EDA) gene is the cause of the most common X-linked form of ED, a gene from the Wnt family (WNT10A) is responsible for the autosomal recessive form of the disease, and two other genes (EDAR and EDARADD) can cause both autosomal recessive and autosomal dominant forms. This review provides the characteristics of the genes involved in ED, their mutation spectra, the level of their expression in human tissues, as well as the interrelation of the aforementioned genes. The domain structures of the corresponding proteins are considered, as well as the molecular genetic pathways in which they are involved. Animal models for studying this disorder are also taken into consideration. Due to the cross-species genes conservation, their mutations cause the disruption of the development of ectoderm derivatives not only in humans, but also in mice, cows, dogs, and even fish. It can be exploited for a better understanding of the etiopathogenesis of ectodermal dysplasias. Moreover, this article brings up the possibility of recurrent mutations in the EDA and WNT10A genes. The review also presents data on promising approaches for intrauterine ED treatment.

Transcriptomic regulation of seasonal coat color change in hares

Color molts from summer brown to winter white coats have evolved in several species to maintain camouflage year-round in environments with seasonal snow. Despite the eco-evolutionary relevance of this key phenological adaptation, its molecular regulation has only recently begun to be addressed. Here, we analyze skin transcription changes during the autumn molt of the mountain hare (Lepus timidus) and integrate the results with an established model of gene regulation across the spring molt of the closely related snowshoe hare (L. americanus). We quantified differences in gene expression among three stages of molt progression-"brown" (early molt), "intermediate," and "white" (late molt). We found 632 differentially expressed genes, with a major pulse of expression early in the molt, followed by a milder one in late molt. The functional makeup of differentially expressed genes anchored the sampled molt stages to the developmental timeline of the hair growth cycle, associating anagen to early molt and the transition to catagen to late molt. The progression of color change was characterized by differential expression of genes involved in pigmentation, circadian, and behavioral regulation. We found significant overlap between differentially expressed genes across the seasonal molts of mountain and snowshoe hares, particularly at molt onset, suggesting conservatism of gene regulation across species and seasons. However, some discrepancies suggest seasonal differences in melanocyte differentiation and the integration of nutritional cues. Our established regulatory model of seasonal coat color molt provides an important mechanistic context to study the functional architecture and evolution of this crucial seasonal adaptation.

Mouse mutations as animal models and biomedical tools for dermatological research

In this overview, we describe the advantages, disadvantages, and specific skin and hair abnormalities in spontaneous mouse mutations, as well as sources of information about models generally applicable to skin diseases. These inbred mouse mutations are used directly to evaluate the genetic bases of mammalian skin diseases and indirectly to study the effects of grafting human tissues onto congenitally immunodeficient mice. Such inbred immuno-deficient mice are productively used to study neoplasia and autoimmune diseases; to produce gene products in transfected human cells and to reconstitute the mouse immune system with human cells. The advantages of using inbred mouse mutants dramatically changed when the ability to produce transgenic mice with induced mutations that increase, nullify, or alter the expression of specific genes was created. Combining the best features of spontaneous and induced mouse mutations provides powerful tools to analyze the developmental biology and the diseases of mammalian skin and hair.

An in vivo method for the detection of somatic mutations at the cellular level in mice

This new method for detection of somatic mutations is based on the fact that recessive mutations at the dilute (d) and leaden (ln) loci change the shape of pigment-cells in the hair follicles from their normal highly dendritic appearance (nucleofugal) to a rounded-up almost non-dendritic form (nucleopetal). Gene action is autonomous and individual mutant melanocytes can be recognised in whole mounts of dorsal skin made after the post-natal onset of melanogenesis. Foetal heterozygotes for d and ln were treated with X-rays (0-200 rad) or procarbazine (0-300 mg/kg body mass by maternal i.p. injection) 17 days after detection of a vaginal plug; whole mounts of dorsal skin (fixed 3 days after birth) were microscopically scanned for mutant melanocytes in the hair follicles.About half a million follicular melanocytes were present in the 2 mounts made per mouse. Mutant cells were mainly in the form of small intrafollicular clones; the few mount containing large interfollicular clones were excluded from the analysis. For both treatments, dose-response relationships showed good fits to both a quadratic and a power-law curve. Equations for the latter were: For X-rays, y = 3.2 x 10(-5) + 3.12 x 10(-9) D2.07; for procarbazine, y = 3.6 x 10(-5) + 0.4 x 10(-10) D2.60. However, neither of these differed significantly from a square-law relationship. The estimated mutation rate at the 100 rad X-ray level of 4.7 x 10(-7)/rad/locus was in good agreement with that obtained by Russell and Major's (1957) pioneer studies of somatic mutation in mice, by looking for mutant patches in the coat ("spot test"). Possible ways in which the present method might be improved and extended are discussed.