Abstract：Fibroblast growth factor 18 (Fgf18) is a secreted signaling molecule and involved in regulating hair growth cycle of mouse (Mus musculus) and cashmere goat (Capra hircus). Primers attached with XbaⅠ and SacⅠ restriction enzymes were designed to clone Fgf18 CDS sequence, and then the PCR product was ligated to the downstream of ultra-high sulfur keratin (UHS) promoter. For application in somatic cell nuclear transfer (SCNT), enhanced green fluorescent protein gene (EGFP) and neomycin gene (Neo) promoted by cytomegalovirus (CMV) promoter were added into the recombinant plasmid. Four restriction enzymes (SacⅠ, BglⅡ, SphⅠ and EcoT14Ⅰ) digestion results showed that the follicle-specific expression vector of Fgf18 gene was successfully constructed, named as pUHS-Fgf18. Three positive transgenic mice were obtained by using pronuclear microinjection, and the integration efficiency was 5.8%. RT-PCR and Western blot results showed that the expression levels of Fgf18 were significantly increased in the skin of transgenic mice, compared to controls (P＜0.05). In order to verify the tissue-specific expression, the expression levels of Fgf18 mRNA were also detected in transgenic mice skin, liver, kidney, heart, testis, skeletal muscle, spleen, brain, lung, stomach and small intestine tissues by using RT-PCR. The results showed that the expression levels of Fgf18 mRNA were significantly increased in transgenic mouse skin (P＜0.05) and there were no significant difference in other tissues between transgenic mouse and controls (P＞0.05). Above mentioned research indicated that pUSH-Fgf18 vector can specifically express Fgf18 in skin. Then RT-PCR was used to detect the copy number of Fgf18 in transgenic mice. The result showed that they were ranging from 8~210, and no copy was detected in controls. This study successfully established a transgenic mouse model, which can serve as a favorable tool to study the function and mechanism of Fgf18 in hair growth cycle, and will provide a theoretical basis to produce Fgf18 gene modified cashmere goats.
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