Subcellular localization, expression patterns, SNPs and association analyses of the porcine HUMMLC2B gene

Abstract

Myosin regulatory light chain (MLC) regulates myofilament activation via phosphorylation by Ca(2+) dependant myosin light chain kinase. In order to further understand the functions of the porcine fast myosin regulatory light chain gene (HUMMLC2B) in muscle, the subcellular localization, the temporal and spatial distributions of its gene product were analyzed, and the association between the presence of specific polymorphisms and commercial meat traits in pig was also examined. HUMMLC2B was demonstrated to localize both in the cytoplasm and the nucleus by confocal fluorescence microscopy. Real-time PCR further revealed HUMMLC2B expression variation in a waveform manner in the skeletal muscle of both Chinese Tongcheng and Western Landrace pig breeds at days 33, 65 and 90 post coitum (pc). After birth, the expression levels of HUMMLC2B were also found to decrease gradually with age. Our spatial expression analysis showed that HUMMLC2B was highly expressed in the semitendinosus, gastrocnemius, biceps femoris and longissimus dorsi muscles. In contrast, only low levels of expression of this gene were evident in fat, and no expression was detectable in brain, heart, kidney, lung, liver, lymph node, spleen, stomach, or in either large or small intestine. A total of 23 potential polymorphisms, comprising 3 exonic and 20 intronic, were detectable in the porcine HUMMLC2B gene and the G1094A, T1513C, G1876A and T2005G polymorphisms were further analyzed. The significant associations between the T1513C, G1876A and T2005G polymorphisms with marbling score, dressing percent and meat color, respectively, were identified (P < 0.05). Associations with the percentage of leaf fat could also be demonstrated by analysis of haplotypes harboring these three polymorphisms. Our current results thus shed further light on the roles and functions of the HUMMLC2B gene in muscle.

BOARD-INVITED REVIEW: The biology and regulation of preadipocytes and adipocytes in meat animals1,2

“…For example, distal-less homeobox 5 (Cheng et al, 2008), fatty acid binding protein 4 and 5 (Estelle et al, 2006), GH 1 and its releasing hormone (Franco et al, 2005), 11 β hydroxysteroid dehydrogenase isoform 1 (Otieno et al, 2005), IGF-1 (Estany et al, 2007), leptin receptor (Ovilo et al, 2005), malic enzyme 1 (Vidal et al, 2006), mitogen-activated protein kinase (MAPK) 8 (Otieno et al, 2005), PPARγ, coactivator-1α (Stachowiak et al, 2007), and pituitary specific transcription factor 1 (Franco et al, 2005) significantly influence backfat thickness in the carcass. Carbonic anhydrase 3 (Wang et al, 2006b) and fatty acid binding protein 3 (Arnyasi et al, 2006) were found to be associated with intramuscular fat content, whereas liver X receptor α (Yu et al, 2006), myosin light chain 2 fast skeletal (Wang et al, 2006a), and resistin (Otieno et al, 2005) significantly affect marbling in pork. Three genes, capping protein (actin filament) muscle Z-line, β , IGFBP2 , and myosin light chain 2 fast skeletal (Wang et al, 2006b), have a significant impact on leaf fat weight.…”

Molecular characterization, expression profile and polymorphisms of the porcine TNNC2 gene

“…Therefore, the detected polymorphisms could be useful markers for quantitative trait loci (QTL) mapping. In pigs, several genes have been screened for SNPs, and a comparable or even higher frequency of variation has been revealed (Chen et al 2004; Wang et al 2006, Mei et al 2007). Furthermore, many studies have provided abundant information on mapping of meat quality genes in the pig.…”

Isolation, expression patterns and SNP frequencies of the porcine PHKG2 gene

“…Analysis of real-time PCR showed that PHKG2 gene was expressed in all the detected tissues. The real-time PCR technique is an accurate and sensitive method, and many studies used it to determine the relative quantification of mRNA or DNA (Wang et al, 2006). The gamma subunit of PhK had two tissue-specific isoforms, muscle and liver, encoded by PHKG1 gene and PHKG2 gene, respectively (Hancock and Rice, 2006).…”