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Wu W.,Key Laboratory of Swine Genetics and Breeding | Wu W.,Key Laboratory of Agriculture Animal Genetics | Wu W.,Huazhong Agricultural University | Xu D.,Key Laboratory of Swine Genetics and Breeding | And 17 more authors.
Livestock Science | Year: 2011

Pitx2 is a bicoid-related homeobox gene, which has been demonstrated to play a critical role in muscle cell proliferation and muscle formation. However, the molecular characteristics of Pitx2c in pigs have not been investigated. In the present study, 2316 bp full-length cDNA of porcine Pitx2c, which contains a 981 bp open reading frame (ORF) encoding 326 amino acids, was isolated. Multiple sequence alignment results showed that porcine Pitx2c full-length cDNA and Pitx2c protein sequences were highly conserved, sharing 91.80% and 86.58% nucleotide identities to human and mouse Pitx2c respectively, while amino acid identities reached 99.11% and 97.03% respectively. However, the identities are relatively lower compared with other isoforms, and phylogenic analysis also indicated that Pitx2c was distinguished from other isoforms. The Pitx2a, Pitx2b and Pitx2c were formed three independent branches respectively. Furthermore, we examined the expression levels and distribution of porcine Pitx2c in different tissues using semi-quantitative RT-PCR method and the result proved that it was most highly expressed in the skeletal muscle. In addition, real-time quantitative PCR was employed to assay the expression patterns of porcine Pitx2c in muscle development. Our results showed that porcine Pitx2c was expressed higher in Yorkshire pigs than that in Meishan and the expression levels were remarkably different at 60 d and 120 d (P<. 0.05). Further analysis indicated that Pitx2c expression was up-regulated from 3 d to 120 d reaching its peak at 120 d, thereafter down-regulated from 120 d to 180 d and Pitx2c expression levels at 120 d were significantly higher than other stages except at 150 d (P<. 0.05). While the data of Pitx2c expression in different muscles revealed that its expression levels in biceps femoris were obviously higher as compared with soleus, masseter and semitendinosus (P<. 0.05). Taken together, our data provide fundamental evidence for Pitx2c as a functional candidate gene affecting pig meat quality. © 2011.


Jiao Q.,Key Laboratory of Swine Genetics and Breeding | Jiao Q.,Key Laboratory of Agriculture Animal Genetics | Jiao Q.,Huazhong Agricultural University | Lei M.,Key Laboratory of Swine Genetics and Breeding | And 14 more authors.
Molecular Biology Reports | Year: 2011

IGFI signaling pathway is sufficient to regulate myofibre hypertrophy postnatally, which is associated with muscle mass in economically livestock. In the present study, we drafted the developmental expression pattern of eight genes implicated in IGFI system across six stages of postnatal myofibre growth in Yorkshire and Tongcheng pigs. The results indicated that GRB2 may contribute to increased DNA content in postnatal myofibre hypertrophy via GRB2-Ras-Raf-MEK-ERK sub-pathway; INSR, PDK1, IRS1 and eIF4E may contribute to high growth rate via stimulating the rate of protein synthesis and inhibiting the rate of protein degradation. In addition, the results suggested 60 days maybe a very important stage in postnatal myofibre growth. Moreover, higher mRNA level of IRS1 and GLUT4 maybe associated with inferior meat quality in Yorkshire compared to Tongcheng pig. Therefore, IGFI signaling pathway regulates myofibre hypertrophy postnatally via complicated signal effectors, which may have negative impact on meat quality simultaneously. © 2011 Springer Science+Business Media B.V.


Wu W.,Key Laboratory of Swine Genetics and Breeding | Wu W.,Huazhong Agricultural University | Ren Z.,Key Laboratory of Swine Genetics and Breeding | Ren Z.,Huazhong Agricultural University | And 8 more authors.
Molecular Biology Reports | Year: 2011

Six1 belongs to the Six gene family that includes six members in mammals (from Six1 to Six6). It has been demonstrated that Six1 homeodomain transcription factor is implicated in myogenesis. However, the molecular characteristics of Six1 in pigs have not been reported. In this study, we isolated and characterized the porcine Six1 gene full-length cDNA, genomic DNA and proximal promoter sequence. Semi-quantitative RT-PCR results confirmed that porcine Six1 was highly expressed in skeletal muscle. Realtime quantitative PCR results showed that porcine Six1 was highly expressed in embryonic stage and no significant expression differences is observed between Meishan and Yorkshire pigs. Furthermore, Six1 expression was significantly different among different developmental stages in Yorkshire pigs and the expression trend was up-regulated from 3 days to 180 days, reaching its highest expression level at 180 days. In addition, the data of Six1 expression in different muscles demonstrated that Six1 was a fast-twitch muscle high expression gene. PCR-HindII-RFLP was established to detect a C/T mutation and an A/G mutation which were present in promoter and intron, respectively. Meanwhile, their associations with economic traits were assessed in Meishan × Yorkshire F2 reference family. The statistical results revealed that the two HindII polymorphisms of porcine Six1 had significant associations with several meat quality traits (P <0.05). Taken together, these studies suggest that porcine Six1 may play an important role in skeletal muscle growth and meat quality. © Springer Science+Business Media B.V. 2010.


PubMed | Key Laboratory of Swine Genetics and Breeding
Type: Journal Article | Journal: Molecular biology reports | Year: 2011

Six1 belongs to the Six gene family that includes six members in mammals (from Six1 to Six6). It has been demonstrated that Six1 homeodomain transcription factor is implicated in myogenesis. However, the molecular characteristics of Six1 in pigs have not been reported. In this study, we isolated and characterized the porcine Six1 gene full-length cDNA, genomic DNA and proximal promoter sequence. Semi-quantitative RT-PCR results confirmed that porcine Six1 was highly expressed in skeletal muscle. Real-time quantitative PCR results showed that porcine Six1 was highly expressed in embryonic stage and no significant expression differences is observed between Meishan and Yorkshire pigs. Furthermore, Six1 expression was significantly different among different developmental stages in Yorkshire pigs and the expression trend was up-regulated from 3 days to 180 days, reaching its highest expression level at 180 days. In addition, the data of Six1 expression in different muscles demonstrated that Six1 was a fast-twitch muscle high expression gene. PCR-HindII-RFLP was established to detect a C/T mutation and an A/G mutation which were present in promoter and intron, respectively. Meanwhile, their associations with economic traits were assessed in Meishan Yorkshire F2 reference family. The statistical results revealed that the two HindII polymorphisms of porcine Six1 had significant associations with several meat quality traits (P<0.05). Taken together, these studies suggest that porcine Six1 may play an important role in skeletal muscle growth and meat quality.


PubMed | Key Laboratory of Swine Genetics and Breeding
Type: Journal Article | Journal: Molecular biology reports | Year: 2011

IGFI signaling pathway is sufficient to regulate myofibre hypertrophy postnatally, which is associated with muscle mass in economically livestock. In the present study, we drafted the developmental expression pattern of eight genes implicated in IGFI system across six stages of postnatal myofibre growth in Yorkshire and Tongcheng pigs. The results indicated that GRB2 may contribute to increased DNA content in postnatal myofibre hypertrophy via GRB2-Ras-Raf-MEK-ERK sub-pathway; INSR, PDK1, IRS1 and eIF4E may contribute to high growth rate via stimulating the rate of protein synthesis and inhibiting the rate of protein degradation. In addition, the results suggested 60 days maybe a very important stage in postnatal myofibre growth. Moreover, higher mRNA level of IRS1 and GLUT4 maybe associated with inferior meat quality in Yorkshire compared to Tongcheng pig. Therefore, IGFI signaling pathway regulates myofibre hypertrophy postnatally via complicated signal effectors, which may have negative impact on meat quality simultaneously.

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