Transcriptomic Research On The Wrinkled Skin Of Xiang Pigs

Xiang pig with wrinkled skin(ZXP)is a variety from Congjiang Xiang pig covered by progeria skin.The skin is the first defense barrier of the body and the important part of the natural immune system,which provide functions of protection,sensation,thermoregulation,absorption,metabolism,secretion and excretion.As the pig is matured and old enough,the skin appears natural aging phenomenon,including skin wrinkle,roughness,loss of elasticity and pigmentation.However,the phenotype of wrinkled skin in ZXP started from the suckling period,which might be resulted from the genetic variation.In order to reveal the molecular mechanism of wrinkled skin in Xiang pig,transcriptome sequencing was carried out on the wrinkled skin of ZXP taking the normal Xiang Pigs(XP)as control.The results were as following.The characteristics of ZXP presents rhomboid or “three vertical lines”-like wrinkles on the forehead,combined with lots of vertical wrinkles on the whole body and limbs.The wrinkled skin of ZXP looked like the striped skin of zebra.Based on the observation by eye and microscope,the ZXP epidermis was thickened,hardened and rough,the elasticity of skin was much poor,the distribution of skin coat was uneven,and the subcutaneous fat layer was much thinner.The structure of dermal collagen fiber were much disorder.A total of more than 60 G reads were obtained from the sequencing data of skin from ZXP and XP.According to the statistical analysis by Subread_featurecount software,14801 genes were identified,including 69 genes specifically expressed in XP and 420 genes expressed only in the wrinkled skin of ZXP.It showed that about80% of genes expressed in Xiang Pig skin were located at the medium level.Total of692 differentially expressed genes were identified from ZXP with 278 genes were up-regulated and 414 genes down-regulated.And 3716 deferentially splicing events were detected from 2635 genes based on alternative splicing analysis,in which 2336 splicing variants were significantly increased and 1380 were obviously decreased.Ofthose,four genes were randomly selected and verified by qPCR method,and the results were consistent with the trend of transcriptome analysis.The results of GO and KEGG analysis indicated that the deferentially expressed genes involved in many GO terms related with skin development,such as calcium ion binding(GO: 0005509),DNA-binding transcription factor activity,RNA polymerase II-specific(GO:0000981),hair follicle development(GO:0001942),skin development(GO: 0043588),keratin filament(GO: 0045095),collagen-containing extracellular matrix(GO: 0062023),together with four KEGG pathways including ECM-receptor interaction(ssc04512),focal adhesion(ssc04510),estrogen signaling pathway(ssc04915)and wnt signaling pathway(ssc04310).Thus,9 candidate genes were selected out,including 4 down-regulated genes,VANGL2,KRT27,KRT25 and LEF1,and 5 up-regulated genes,THBS1,PLCB4,THBS4,WNT2,and COL6A5.Furthermore,two genes LEF1 and COL6A5,were identified to harbour exon skipping events.To sum up,the present paper analyzed the gene expression and variation in the wrinkled skin of Xiang pig by compared transcriptomics technology.The gene expression profiles and gene differential expression patterns of the wrinkle skin from Xiang pig were constructed,and 9 deferentially expressed genes were chosen as candidates related with skin wrinkle formation.It is of great significant to indicate the molecular mechanism of wrinkle formation in pig and the progeria skin in patient.