Abstract
BackgroundMicroRNAs (miRNAs) are a large family of endogenous, non-coding RNAs, about 22 nucleotides long, which regulate gene expression through sequence-specific base pairing with target mRNAs. Extensive studies have shown that miRNA expression in the skin changes remarkably during distinct stages of the hair cycle in humans, mice, goats and sheep.ResultsIn this study, the skin tissues were harvested from the three stages of hair follicle cycling (anagen, catagen and telogen) in a fibre-producing goat breed. In total, 63,109,004 raw reads were obtained by Solexa sequencing and 61,125,752 clean reads remained for the small RNA digitalisation analysis. This resulted in the identification of 399 conserved miRNAs; among these, 326 miRNAs were expressed in all three follicular cycling stages, whereas 3, 12 and 11 miRNAs were specifically expressed in anagen, catagen, and telogen, respectively. We also identified 172 potential novel miRNAs by Mireap, 36 miRNAs were expressed in all three cycling stages, whereas 23, 29 and 44 miRNAs were specifically expressed in anagen, catagen, and telogen, respectively. The expression level of five arbitrarily selected miRNAs was analyzed by quantitative PCR, and the results indicated that the expression patterns were consistent with the Solexa sequencing results. Gene Ontology and KEGG pathway analyses indicated that five major biological pathways (Metabolic pathways, Pathways in cancer, MAPK signalling pathway, Endocytosis and Focal adhesion) accounted for 23.08% of target genes among 278 biological functions, indicating that these pathways are likely to play significant roles during hair cycling.ConclusionsDuring all hair cycle stages of cashmere goats, a large number of conserved and novel miRNAs were identified through a high-throughput sequencing approach. This study enriches the Capra hircus miRNA databases and provides a comprehensive miRNA transcriptome profile in the skin of goats during the hair follicle cycle.
Highlights
MicroRNAs are a large family of endogenous, non-coding RNAs, about 22 nucleotides long, which regulate gene expression through sequence-specific base pairing with target mRNAs
Solexa-sequencing of small RNAs In order to identify miRNAs involved in the three phrases of the hair cycle, three small RNA libraries representing the above three phrases were constructed from a mixed pool of ten adult cashmere goat skin samples
Our results demonstrate that miRNA expression is abundant in the skin of cashmere goats, as a total of 399 miRNAs were found in the three stages of the hair follicle (HF) cycle (Additional file 2: Figure S2)
Summary
MicroRNAs (miRNAs) are a large family of endogenous, non-coding RNAs, about 22 nucleotides long, which regulate gene expression through sequence-specific base pairing with target mRNAs. Extensive studies have shown that miRNA expression in the skin changes remarkably during distinct stages of the hair cycle in humans, mice, goats and sheep. MicroRNAs (miRNAs) are a large family of endogenous, non-coding RNAs, about 22-nucleotide (nt) long, which regulate gene expression through sequencespecific base pairing with target mRNAs [8]. MiRNAs are involved in the control of each stage of the hair cycle and regulate the transition between distinct hair-cycle stages by targeting different signalling pathways and transcription factors. MiR-31 is involved in the establishment of an optimal balance of gene expression in the HF, which is required for its proper growth and hair-fibre formation [15] The expression of miR-31 markedly increases during anagen and decreases during catagen and telogen. miR-31 is involved in the establishment of an optimal balance of gene expression in the HF, which is required for its proper growth and hair-fibre formation [15]
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