Bioactive motifs of agouti signal protein

RNA-Seq Reveals the Roles of Long Non-Coding RNAs (lncRNAs) in Cashmere Fiber Production Performance of Cashmere Goats in China

Long non-coding RNAs (lncRNAs) are a kind of non-coding RNA being >200 nucleotides in length, and they are found to participate in hair follicle growth and development and wool fiber traits regulation. However, there are limited studies reporting the role of lncRNAs in cashmere fiber production in cashmere goats. In this study, Liaoning cashmere (LC) goats (n = 6) and Ziwuling black (ZB) goats (n = 6) with remarkable divergences in cashmere yield, cashmere fiber diameter, and cashmere color were selected for the construction of expression profiles of lncRNAs in skin tissue using RNA sequencing (RNA-seq). According to our previous report about the expression profiles of mRNAs originated from the same skin tissue as those used in the study, the cis and trans target genes of differentially expressed lncRNAs between the two caprine breeds were screened, resulting in a lncRNA-mRNA network. A total of 129 lncRNAs were differentially expressed in caprine skin tissue samples between LC goats and ZB goats. The presence of 2 cis target genes and 48 trans target genes for the differentially expressed lncRNAs resulted in 2 lncRNA-cis target gene pairs and 93 lncRNA-trans target gene pairs. The target genes concentrated on signaling pathways that were related to fiber follicle development, cashmere fiber diameter, and cashmere fiber color, including PPAR signaling pathway, metabolic pathways, fatty acid metabolism, fatty acid biosynthesis, tyrosine metabolism, and melanogenesis. A lncRNA-mRNA network revealed 22 lncRNA-trans target gene pairs for seven differentially expressed lncRNAs selected, of which 13 trans target genes contributed to regulation of cashmere fiber diameter, while nine trans target genes were responsible for cashmere fiber color. This study brings a clear explanation about the influences of lncRNAs over cashmere fiber traits in cashmere goats.

Transcriptome analysis provides insight into the role of the melanin pathway in two differently pigmented strains of the turtle Pelodiscus sinensis

Pelodiscus sinensis is the most common turtle species raised in East and Southeast Asia. The Japanese strain and the Qingxi black strain are important aquatic breeds of P. sinensis in China with unique characteristics in terms of production performance and appearance, including skin color. In this study, melanin content measure and histological analysis on skin samples of these two strains were carried out to compare their color characteristics. The results showed that Qingxi black turtles clearly have a greater ability to deposit melanin than the Japanese strain especially in the abdomen. Then, de novo transcriptome assembly and differential expression profiling analyses on the ventral skin from the two strains were performed to identify the genes responsible for the differences in skin color using the Illumina RNA-Seq system with three biological replicates. A total of 19,331 annotated unigenes were found by aligning to the reference genome of P. sinensis using TopHat v2.0.12. Differential expression analysis revealed that 670 genes were expressed differently, including 185 upregulated genes and 485 downregulated genes in Qingxi black strain using the DESeq R package (|log2FoldChange| ≥ 1, padj < 0.05). Sixteen differentially expressed genes (DEGs), which were randomly selected, were confirmed by quantitative real-time PCR (qRT-PCR). GO and KEGG analyses revealed four DEGs (agouti signaling protein, frizzled family receptor 1, phospholipase C, and protein kinase C) were related to melanogenesis pathway. Gene expression levels of the four DEGs as well as three genes from the tyrosinase gene family were measured by qRT-PCR. The results indicated that agouti signaling protein, tyrosinase-related protein, and dopachrome tautomerase could be the main genes responsible for the difference in abdominal skin color between the two turtle strains. This study provided valuable information for further analysis of the melanogenesis mechanisms in different varieties of P. sinensis.

Molecular and phenotypic analysis of 25 recessive, homozygous-viable alleles at the mouse agouti locus

Agouti is a paracrine-acting, transient antagonist of melanocortin 1 receptors that specifies the subapical band of yellow on otherwise black hairs of the wild-type coat. To better understand both agouti structure/function and the germline damage caused by chemicals and radiation, an allelic series of 25 recessive, homozygous-viable agouti mutations generated in specific-locus tests were characterized. Visual inspection of fur, augmented by quantifiable chemical analysis of hair melanins, suggested four phenotypic categories (mild, moderate, umbrous-like, severe) for the 18 hypomorphs and a single category for the 7 amorphs (null). Molecular analysis indicated protein-coding alterations in 8 hypomorphs and 6 amorphs, with mild-moderate phenotypes correlating with signal peptide or basic domain mutations, and more devastating phenotypes resulting from C-terminal lesions. Ten hypomorphs and one null demonstrated wild-type coding potential, suggesting that they contain mutations elsewhere in the > or = 125-kb agouti locus that either reduce the level or alter the temporal/spatial distribution of agouti transcripts. Beyond the notable contributions to the field of mouse germ cell mutagenesis, analysis of this allelic series illustrates that complete abrogation of agouti function in vivo occurs most often through protein-coding lesions, whereas partial loss of function occurs slightly more frequently at the level of gene expression control.

Influence of alpha-melanocyte-stimulating hormone and ultraviolet radiation on the transfer of melanosomes to keratinocytes

The epidermal melanin unit in human skin is composed of melanocytes and keratinocytes. Melanocytes, located in the basal layer of the epidermis, manufacture melanin-loaded organelles called melanosomes. Through their dendritic processes, melanocytes distribute melanosomes to neighboring keratinocytes, where their presence confers to the skin its characteristic color and photoprotective properties. In this study, we used murine melanocytes and keratinocytes alone and in coculture to characterize the processes involved in melanosome transfer. Ultraviolet (UV) radiation induced an accumulation of melanosomes in melanocytes, whereas treatment with a-melanocyte-stimulating hormone (MSH) induced exocytosis of melanosomes accompanied by ruffling of the melanocyte membrane. We found that keratinocytes phagocytose melanosomes and latex beads equally well and that this phagocytic process was increased by exposure of keratinocytes to UV radiation or to MSH. Coculture of melanocytes and keratinocytes resulted in an increase in MSH released to the medium. Gene array analysis of MSH-treated melanocytes showed up-regulation of many genes associated with exocytosis. In our studies, we never observed cytophagocytosis of melanosome-filled processes. This result, together with the other findings, suggests that a combination of signals that increase melanosome production and release by melanocytes and that stimulate phagocytosis by keratinocytes are the most relevant mechanisms involved in skin tanning.