Cellular retinoic acid-binding protein 1 （CRABP1） is a well-conserved member of cytosolic lipid-binding protein family. It is an important modulator of retinoic acid signaling. Long serial analysis of gene expression （LongSAGE） analysis suggested that CRABP1 gene was differentially expressed during prenatal skeletal muscle development in porcine. Here, we obtained the full-length coding region sequence and genomic sequence of the porcine CRABP1 gene and analyzed its genomic structures. Subsequently, we examined CRABP1 chromosome assignment using INRA-University of Minnesota 7 000 porcine radiation hybrid panel （IMpRH） and explored its tissue distribution in adult Tongcheng pigs and dynamical expression profiles in prenatal skeletal muscle （33, 65 and 90 days post coitus, dpc） from Landrace （lean-type） （described as L33, L65 and L90） and Tongcheng pigs （obese-type） （described as T33, T65 and T90）. The CRABPI gene was mapped to chromosome 7ql 1-q23 and closely linked to the microsatellite marker SWR1928. Quantitative real-time PCR showed that CRABP1 mRNA was highly expressed in lung and stomach, moderately expressed in placenta and uterus, and weakly expressed in other tissues. Moreover, CRABP1 gene was down-regulated during prenatal skeletal muscle development in both Landrace and Tongcheng pigs and it was expressed much higher in T33 than L33. Two single-nucleotide polymorphisms （SNPs） were detected by sequencing and mass spectrometry methods, allele frequency analysis indicated that g. 281 （G〉A） and g. 2992 （G〉A）were deviated from Hardy-Weinberg equilibrium in the Landrace and DLY （Duroc×（Landrace×Yorkshire）） pig breeds.
ZHAO Shuan-pingTANG Zhong-linZHOU RongQU Chang-qingZHENG Jian-weiLI Kui
Secreted frizzled-related protein 2 （SFRP2）, a member of the SFRPs family, is associated with cell growth and differentiation in myogenesis. Our previous study suggested that SFRP2 was a potential target of microRNA （miRNA）-I/206, which was considered as myomiRs. To further explore the biological function and regulation mechanisms of the SFRP2 gene in porcine skeletal muscle development, we first analyzed the sequence structure of the porcine SFRP2 gene. Subsequently, we detected its tissue distribution in adult Tongcheng pigs （a Chinese indigenous breed） and investigated its dynamic expression in developmental skeletal muscle （13 prenatal and 7 postnatal time points）in Tongcheng pigs. An interaction analysis between SFRP2 and myomiRs was also performed. The results showed that the expression pattern of the SFRP2 varied greatly across diverse tissues. It exhibited abundant expression in prenatal skeletal muscle and peaked at 55 days post coitus （E55）, and had a lower expression in postnatal skeletal muscle, indicating that the SFRP2 gene might affect porcine embryonic skeletal muscle development. Co-expression analysis revealed that the expression levels of SFRP2 correlated negatively with miRNA-1 （t=-0.570, P-value=0.009） and miRNA-206 （r=-0.546, P-value=0.013）, but positively with SFRP1 （r=0.613, P-value=0.004）. The bioinformatics analysis and dual luciferase assay verified that the SFRP2 was a putative target of miRNA-1/206 in pigs. Therefore, this study is helpful for understanding the biological function and mo- lecular regulation of the SFRP2 gene during porcine skeletal muscle development.
MA Yan-jiaoYANG Ya-lanSUN WeiZHOU RongLI KuiTANG Zhong-lin
