Spatial and temporal control of laminin-332 and -511 expressions during hair morphogenesis

A missense mutation in Lama3 causes androgen alopecia

Hair loss disorders such as androgenetic alopecia have caused serious disturbances to normal human life. Animal models play an important role in exploring pathogenesis of disease and evaluating new therapies. NIH hairless mice are a spontaneous hairless mouse discovered and bred in our laboratory. In this study, we resequenced the genomes of NIH normal mice and NIH hairless mice and obtained 3,575,560 high-quality, plausible SNP loci and 995,475 InDels. The Euclidean distance algorithm was used to assess the association of SNP loci with the hairless phenotype, at a threshold of 0.62. Two regions of chromosome 18 having the highest association with the phenotype contained 345 genes with a total length of 13.98 Mb. The same algorithm was used to assess the association of InDels with the hairless phenotype at a threshold of 0.54 and revealed a region of 25.45 Mb in length, containing 518 genes. The mutation candidate gene Lama3 (NM_010680.2: c.652C>T; NP_034810.1: p. Arg217Cys) was selected based on the results of functional gene analysis and mutation prediction screening. Lama3 (R217C) mutant mice were further constructed using CRISPR/Cas9 technology, and the relationship between Lama3 point mutations and the hairless phenotype were clarified by phenotypic observation. The results showed that male Lama3 point mutation mice started to lose hair on the 80th day after birth, and the hair loss area gradually expanded over time. H&E staining of skin sections showed that the point mutation mice had increased sebaceous glands in the dermis and missing hair follicle structure (i.e., typical symptoms of androgenetic alopecia). This study is a good extension of the current body of knowledge about the function of Lama3, and the constructed Lama3 (R217C) mutant mice may be a good animal model for studying androgenetic alopecia.

Re-investigating the Basement Membrane Zone of Psoriatic Epidermal Lesions: Is Laminin-511 a New Player in Psoriasis Pathogenesis?

Psoriasis is a complex chronic inflammatory skin disease characterized by epidermal thickening on the basis of increased keratinocyte proliferation and insufficient apoptosis. Laminins are important components of the basement membrane (BM) and impact on epidermal keratinocyte growth/apoptosis. Although several laminins are involved in the pathogenesis of psoriasis, it is still controversial about the expression patterns of laminin isoforms and which laminins are important in the development of psoriasis. Because laminin-511 and -332 are key BM components in human skin, and laminin-511 stimulates human hair follicle growth, we asked whether the BM zone in psoriasis shows any laminin-related abnormalities. This showed that the BM expression of laminin-511 and -332 was significantly increased within the skin lesion of psoriasis. Immunofluorescence microscopy revealed that laminin-511, -332, and collagen type IV proteins were also significantly increased in psoriasis-like skin lesions of Imiquimod-treated mice. Transmission electron microscopy showed a few gaps of lamina densa, and its thickness was significantly increased. Finally, laminin-511 treatment significantly stimulated the proliferation and inhibited apoptosis of HaCaT cells, while laminin-α5 chain gene knockdown decreased proliferation and induced apoptosis. These phenomenological observations raise the question of whether laminin-511-controlled keratinocyte growth/death may be a previously overlooked player in the pathogenesis of psoriatic epidermal lesions.

Genome-Wide Association Studies Identify Candidate Genes for Coat Color and Mohair Traits in the Iranian Markhoz Goat

The Markhoz goat provides an opportunity to study the genetics underlying coat color and mohair traits of an Angora type goat using genome-wide association studies (GWAS). This indigenous Iranian breed is valued for its quality mohair used in ceremonial garments and has the distinction of exhibiting an array of coat colors including black, brown, and white. Here, we performed 16 GWAS for different fleece (mohair) traits and coat color in 228 Markhoz goats sampled from the Markhoz Goat Research Station in Sanandaj, Kurdistan province, located in western Iran using the Illumina Caprine 50K beadchip. The Efficient Mixed Model Linear analysis was used to identify genomic regions with potential candidate genes contributing to coat color and mohair characteristics while correcting for population structure. Significant associations to coat color were found within or near the ASIP, ITCH, AHCY, and RALY genes on chromosome 13 for black and brown coat color and the KIT and PDGFRA genes on chromosome 6 for white coat color. Individual mohair traits were analyzed for genetic association along with principal components that allowed for a broader perspective of combined traits reflecting overall mohair quality and volume. A multitude of markers demonstrated significant association to mohair traits highlighting potential candidate genes of POU1F1 on chromosome 1 for mohair quality, MREG on chromosome 2 for mohair volume, DUOX1 on chromosome 10 for yearling fleece weight, and ADGRV1 on chromosome 7 for grease percentage. Variation in allele frequencies and haplotypes were identified for coat color and differentiated common markers associated with both brown and black coat color. This demonstrates the potential for genetic markers to be used in future breeding programs to improve selection for coat color and mohair traits. Putative candidate genes, both novel and previously identified in other species or breeds, require further investigation to confirm phenotypic causality and potential epistatic relationships.