Isolation, characterization, and expression analysis of FGF5 isoforms in cashmere goat

Polymorphisms and mRNA Expression Levels of IGF-1, FGF5, and KAP 1.4 in Tibetan Cashmere Goats

The Tibetan cashmere goat is a precious breed in China and its cashmere is widely used in clothing and textiles. The genes IGF-1, FGF5, and KAP 1.4 have been shown to be crucial regulators of cashmere growth. In this study, we examined mRNA expression levels of these three genes and detected IGF-1, FGF5, and KAP 1.4 SNP loci in the Tibetan cashmere goat. After amplification and sequence alignment of the genes IGF-1, FGF5, and KAP 1.4 among 206 Tibetan cashmere goats, two new SNP loci were detected in gene KAP 1.4, while no SNP loci were found in amplified fragments of genes IGF-1 and FGF5. The expression levels of gene IGF-1 in Baingoin and Nyima counties were significantly higher than in other counties (p < 0.05). Moreover, the expression level of gene FGF5 in Gêrzê was significantly higher than in Rutog. The expression levels of mRNA in KAP 1.4 showed significant variation among seven counties. There were no significant differences in mRNA expression levels of IGF-1, FGF5, and KAP 1.4 in Tibetan cashmere goats when analysed by sex. The gene IGF-1 was slightly up-regulated in one to five-year-old cashmere goats, except in those that were 4 years old. The mRNA expression levels of FGF5 in one and two-year-old cashmere goats was lower compared with those in three to five-year-old cashmere goats. KAP 1.4 was up-regulated across one to five-year-old cashmere goats. In this study, SNP detection and mRNA expression analysis of IGF-1, FGF5, and KAP 1.4 genes was able to add data to genetic evolutionary analysis. Further studies should be carried out in SNPs to detect other fragments in genes IGF-1 and FGF5, as well as signal pathways and gene functions in protein levels of genes IGF-1, FGF5, and KAP 1.4 in the Tibetan cashmere goat.

FGF5 missense mutation is associated with dromedary hair length variation

Several FGF5 mutations are associated with hair length variation in many domestic animals, including New World camelids. The dromedary was investigated in the present study with breeds exhibiting marked variations in hair length. This study aimed to: (1) identify the molecular variation(s) in the three exons of FGF5 of a diverse group of breeds (Mejaheem, Shaele, Sofor, Waddah and Omani; n = 28); (2) examine the association of the identified variants with hair length; (3) validate the association via genotyping the polymorphism in a large population of diverse camels (n = 113); and (4) test the segregation of the identified variant with hair length in a pedigree. A non-synonymous mutation (c.779 C > T) was identified that changes the amino acid from proline to leucine and was found to be associated with different hair length in dromedaries. The variants at c.779 displayed a co-dominance mode of inheritance and three hair length phenotypes: short (C/C), intermediate (C/T) and long (T/T). Across the examined dromedary breeds, both alleles were present, which is probably due to the breeders' preference for an intermediate hair length. When compared with other camelids, the identified variant was found exclusively in dromedaries with the ancestral allele at c.779 being 'C'. This study constitutes the first thorough exploration of the FGF5 gene in dromedaries.

Evidence of post-transcriptional readthrough regulation in FGF5 gene of alpaca

Two different phenotypes are described in alpaca, identified as suri and huacaya, which differ in the type of fleece. The huacaya fleece is characterized by compact, soft and highly crimped fibers, while the suri fleece is longer, straight, less-crimped and lustrous. In our study, the Fibroblast growth factor 5 (FGF5) was investigated as a possible candidate gene for hair length in alpaca (Vicugna pacos). As previously identified in other mammals, our results show that the alpaca FGF5 gene gives rise to a short (FGF5S) and a long (FGF5) isoform. Interestingly, in the long isoform, we observed a point mutation (i.e., a transition C>T at position 499 downstream of the ATG codon) that is able to generate a premature termination codon (PTC). The highly conserved nucleotide and amino acid sequence after PTC suggested a readthrough event (RT) that was confirmed by western blot analysis. The analysis of cDNA sequence revealed motifs and structures of mRNA undergoing RT. In fact, the event is positively influenced by particular signals harbored by the transcript. To the best of our knowledge, this is the first case of a readthrough event on PTC reported for the FGF5 gene and the first case of this translational mechanism in alpaca.

Identification of novel isoforms of dairy goat EEF1D and their mRNA expression characterization

Eukaryotic translation elongation factor 1 delta (EEF1D) gene encodes guanine nucleotide exchange protein eEF1Bδ, which participates in the eukaryotic protein synthesis, and plays important roles in regulating cell cycling and milk production. This study firstly focused on detecting the isoforms of dairy goat EEF1D gene and their mRNA expression characterization. Herein, two novel isoforms, EEF1Da and EEF1Dc, were identified in dairy goat. The entire coding sequences of EEF1Da and EEF1Dc isoforms were 843bp and 267bp in length, respectively. Goat EEF1Da had complete conserved domains of elongation factor 1 (EF1) family, and the evolution of goat EEF1Da isoform was agreed with the evolution of species. Expression pattern analysis of different isoforms revealed relatively ubiquitous expression of EEF1D and EEF1Da. While EEF1Dc only expressed in heart, lung, kidney, adipose and muscle. Combining with the analysis results of cloning, qRT-PCR and bioinformatics, EEF1Da is the major alternative splicing form of EEF1D gene. Interestingly, qRT-PCR result showed that the highest expression of EEF1D was in adipose, which is the major component of mammary. This result was consistent with the early research that EEF1D expressed highly in the mammary, which indicated that EEF1D played a potential key role in regulating adipose development and milk production. All these findings would provide a foundation for the further research of EEF1D gene and development of dairy goat industry.

Fibroblast growth factor 5-short (FGF5s) inhibits the activity of FGF5 in primary and secondary hair follicle dermal papilla cells of cashmere goats

To determine the relationship between fibroblast growth factor 5 (FGF5) and FGF5-short (FGF5s) in dermal papilla cells of cashmere goat primary and secondary hair follicles. We isolated dermal papilla cells from primary hair follicle (PHF) and secondary hair follicle (SHF) of cashmere goat, and found that the FGF5 receptor, fibroblast growth factor receptor 1 (FGFR1), was expressed in these two types of dermal papilla cells. Moreover, adenovirus-mediated overexpression of FGF5 could upregulate the mRNA expression of insulin-like growth factor-1 (IGF-1), versican and noggin that were important for follicle growth maintenance, whereas downregulate the expression of anagen chalone bone morphogenetic protein 4 (BMP4) in dermal papilla cells. However, these alterations were partly reversed by FGF5s overexpression. In conclusion, our results demonstrated that FGF5s acted as an inhibitor of FGF5 in the regulation of anagen-catagen transition of cashmere goat dermal papilla cells.