Molecular Cloning And Expression Analysis Of Genes Involved In The Hair Follicle Development And Coat Color In Jining Gray Goat

Jining Gray Goat (capra hircus) is the world-famous fur-bearing and budge used animalwith its special color and pattern. The coat of Jining gray goat has black and white hairs andthere are three coat colors according to the proportion of black and white hair. The dark-grayindividuals have more than50%black fiber, while the light-gray ones have less than30%black fiber and the gray ones have30%-50%black fiber. The main productions of Jining graygaot are kid-skin and lamb-skin. Abatageing the lamb thirty days after born can get thekid-lambs while the older lambs from the ones older than one month. To reveal the moleculargenetic mechanism of Jining gray goat skin, the real-time quantitative PCR and rapidamplification of cDNA end methods were used in this study. In order to know the structrue ofthe tyrosinase, the bioinformatics technique was used to analyze the complete cDNAsequence which was sequenced in this study. The expression of tyrosinase (TYR), Insulin-likegrowth factor1(IGF-1) and fibroblast growth factor5(FGF5) were evaluated in differentstages of development, while the expression of TYR in different colors was evaluated.Studying and analyzing the structure or regulation mechanism of genes which were closedcontact the hair follicle development or coat color can provide the hereditary data and thetheory basis to improve the characteristics of hair used.Tyrosinase is the key regulatory enzyme of melanogenesis and plays a major role inmammal coat color. For the first time, we have sequenced and characterized the tyrosinase(TYR) of Jining Gray Goat. The full-length cDNA was cloned by RT-PCR and RACEmethods. As a result, one2131bp nucleotide sequence representing the full-length cDNA ofTYR was obtained. The entire open reading frame (ORF) of the TYR is1593bp and encodesfor530amino acids, which is well conserved compared with TYR of various species withhigher degree of sequence similarity with other mammalian (74%-99%) than amphibian, avesand fishes (56%-73%). The deduced amino acids contained one signal peptide, onetransmembrane domain, five N-linked glycosylation sites and two copper binding sites. Thesestructures are relatively conservative in the evolutionary process. The result of real-timequantitative PCR showed that the expression level of TYR was highest in the dark-gray goats and lowest in the light-gray ones, while the coats of dark-gray individuals have more than50%black fiber and light-gray ones less than30%. During the whole life of Jining gray goat,TYR expression level has some changes to follow certain regularity and their coat color willchange correspondingly by investigating the expression level in ten development stages. Aftercomparing the result and the coat phenotype, we presume that it seems to have a positiverelationship between the color depth of coat and the expression level of TYR.In the process of hair follicle growth, IGF-1is playing stimulus growth anddifferentiation of tissues roles. The expression of IGF-1was age-dependent. The IGF-1wasexpressed in every stage of goats after evaluated the IGF-1expression in different stages ofdevelopment and the highest level was found in older lamb stage and the level displayeddescending after rising first. The expression reached the highest level at2-month-old then itdescended. It had some upswing in adult stage instead. This result further validates theage-dependent characteristics of IGF-1expression. Contrasting the results of sheep, it is notdifficult to find the developmental pattern of the sheep skin of IGF-1mRNA has interspecificdifference.FGF5is the unique factor that affects the length of hair by affecting the anagen of hairfollicle among the regulation factors of hair follicle. In this study, the expression trend ofFGF5in different development displayed descending after rising first. It reached the highestlevel at3-day-old then it had some upswing in adult stage. The density and diameter of hairfollicle were smaller during the stage of kid-lambs, while the expression of FGF5was highest.We presume that FGF5has inhibitory action for development of hair follicle. This result isconcord with the previously reports and this result further validates the affecting of FGF5fordevelopment of hair follicle.