• BMB Reports
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• 제30권5호
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• pp.362-369
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• 1997

Multiple phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit in RNA polymerase II (RNAP II) is thought to play an important role in the transcription cycle. The preinitiation complex in a partially purified complete transcription system suggested that RNA polymerase IIA containing unphosphorylated CTD is involved in complex assembly, whereas RNA polymerase IIO containing Ser and Thr phosphorylated CTD is not involved in preinitiation complex assembly. Recently a minimal transcription system was developed which requires chemically defined minimal components for its transcription: TBP, TFIIB, TFIIF, RNAP II and a supercoiled adenovirus-2 major late promoter (Ad-2 MLP). It would be using interesting to determine the consequence of CTD phosphorylation on preinitiation complex formation using the minimal transcription system. Contrary to the results from the partially purified complete transcription system, both RNA polymerase IIA and IIO are equally recruited in the preinitiation complex formation. The discrepancy may result from the two different assays used to determine complex formation, the use of chemically undefined complete and defined minimal transcription systems. This implicates that some factors in the complete transcription system are involved in the distinction between RNAP IIA and IIO in complex assembly. In addition multiple tyrosine phosphorylation of the CTD of RNAP II was prepared with c-Abl kinase and its recruiting ability in the preinitiation complex was examined. Compare with Ser and Thr phosphorylated RNAP IIO, Tyr phosphorylated RNAP IlOy forms a stable preinitiation complex in both the minimal and complete transcription systems. Based on these results, it seems that tyrosine phosphorylation of the CTD is important in the transcription cycle on the special subset of class-II promoter or has a different role in the transcription process.

• Reproductive and Developmental Biology
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• 제36권4호
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• pp.237-241
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• 2012

Embryonic genome activation (EGA) is the first major transition that occurs after fertilization, and entails a dramatic reprogramming of gene expression that is essential for continued development. Although it has been suggested that EGA in porcine embryos starts at the four-cell stage, recent evidence indicates that EGA may commence even earlier; however, the molecular details of EGA remain incompletely understood. The RNA polymerase II of eukaryotes transcribes mRNAs and most small nuclear RNAs. The largest subunit of RNA polymerase II can become phosphorylated in the C-terminal domain. The unphosphorylated form of the RNA polymerase II largest subunit C-terminal domain (IIa) plays a role in initiation of transcription, and the phosphorylated form (IIo) is required for transcriptional elongation and mRNA splicing. In the present study, we explored the nuclear translocation, nuclear localization, and phosphorylation dynamics of the RNA polymerase II C-terminal domain in immature pig oocytes, mature oocytes, two-, four-, and eight-cell embryos, and the morula and blastocyst. To this end, we used antibodies specific for the IIa and IIo forms of RNA polymerase II to stain the proteins. Unphosphorylated RNA polymerase II stained strongly in the nuclei of germinal vesicle oocytes, whereas the phosphorylated form of the enzyme was confined to the chromatin of prophase I oocytes. After fertilization, both unphosphorylated and phosphorylated RNA polymerase II began to accumulate in the nuclei of early stage one-cell embryos, and this pattern was maintained through to the blastocyst stage. The results suggest that both porcine oocytes and early embryos are transcriptionally competent, and that transcription of embryonic genes during the first three cell cycles parallels expression of phosphorylated RNA polymerase II.

• Asian-Australasian Journal of Animal Sciences
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• 제30권11호
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• pp.1620-1632
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• 2017

Objective: This study evaluated the effects of a traditional Chinese medicine formula (TCMF) on muscle fiber characteristics in finishing pigs and the effects of the formula's extract (distilled water, ethyl acetate and petroleum ether extraction) on porcine cell proliferation and isoforms of myosin heavy chain (MyHC) gene expression in myocytes. Methods: In a completely randomized design, ninety pigs were assigned to three diets with five replications per treatment and six pigs per pen. The diets included the basal diet (control group), TCMF1 (basal diet+2.5 g/kg TCMF) and TCMF2 (basal diet+5 g/kg TCMF). The psoas major muscle was obtained from pigs at the end of the experiment. Muscle fiber characteristics in the psoas major muscle were analyzed using myosin ATPase staining. Cell proliferation was measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye and cytometry. Isoforms of MyHC gene expression were detected by real-time quantitative polymerase chain reaction. Results: The final body weight and carcass weight of finishing pigs were increased by TCMF1 (p<0.05), while the psoas major muscle cross-sectional area was increased by TCMF (p<0.05). The cross-sectional area and diameter of psoas major muscle fiber Ι, IIA, and IIB were increased by TCMF2 (p<0.05). The cross-sectional area and fiber diameter of psoas major muscle fiber IIA and IIB were increased by diet supplementation with TCMF1 (p<0.05). Psoas major muscle fiber IIA and IIB fiber density from the pigs fed the TCMF1 diet and the type IIB fiber density from the pigs fed the TCMF2 diet were lower compared to pigs fed the control diet (p<0.05). Pigs fed TCMF2 had a higher composition of type Ι fiber and a lower percentage of type IIB fiber in the psoas major muscle (p<0.05). The expression levels of MyHC Ι, MyHC IIa, and MyHC IIx mRNA increased and the amount of MyHC IIb mRNA decreased in the psoas major muscle from TCMF2, whereas MyHC Ι and MyHC IIx mRNA increased in the psoas major muscle from TCMF1 (p<0.05). Peroxisome proliferator-activated receptor ${\gamma}$ $coactivator-1{\alpha}$ and CaN mRNA expression in the psoas major muscle were up-regulated by TCMF (p<0.05). Porcine skeletal muscle satellite cell proliferation was promoted by $4{\mu}g/mL$ and $20{\mu}g/mL$ TCMF water extraction (p<0.05). Both $1{\mu}g/mL$ and $5{\mu}g/mL$ of TCMF water extraction increased MyHC IIa, MyHC IIb, and MyHC IIx mRNA expression in porcine myocytes (p<0.05), while MyHC Ι mRNA expression in porcine myocytes was decreased by $5{\mu}g/mL$ TCMF water extraction (p<0.05). Porcine myocyte MyHC Ι and MyHC IIx mRNA expression were increased, and MyHC IIa and MyHC IIb mRNA expression were down-regulated by $5{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). MyHC Ι and MyHC IIa mRNA expression in porcine myocytes were increased, and the MyHC IIb mRNA expression was decreased by $1{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). Four isoforms of MyHC mRNA expression in porcine myocytes were reduced by $5{\mu}g/mL$ TCMF petroleum ether extraction (p<0.05). MyHC IIa mRNA expression in porcine myocytes increased and MyHC IIb mRNA expression decreased by $1{\mu}g/mL$ in a TCMF petroleum ether extraction (p<0.05). Conclusion: These results indicated that TCMF amplified the psoas major muscle cross-sectional area through changing muscle fiber characteristics in finishing pigs. This effect was confirmed as TCMF extraction promoted porcine cell proliferation and affected isoforms of MyHC gene expression in myocytes.

• Asian-Australasian Journal of Animal Sciences
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• 제29권4호
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• pp.457-463
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• 2016

The goal of this work was to investigate the correlations between MyHC mRNA transcription and their corresponding protein expressions in porcine longissimus muscle (LM) during postnatal growth of pigs. Five DLY ($Duroc{\times}Landrace{\times}Yorkshire$) crossbred pigs were selected, slaughtered and sampled at postnatal 7, 30, 60, 120, and 180 days, respectively. Each muscle was subjected to quantity MyHCs protein contents through an indirect enzyme-linked immunosorbent assay (ELISA), to quantity myosin heavy-chains (MyHCs) mRNA abundances using real-time polymerase chain reaction. We calculated the proportion (%) of each MyHC to total of four MyHC for two levels, respectively. Moreover, the activities of several key energy metabolism enzymes were determined in LM. The result showed that mRNA transcription and protein expression of MyHC I, IIa, IIx and IIb in LM all presented some obvious changes with postnatal aging of pigs, especially at the early stage after birth, and their mRNA transcriptions were easy to be influenced than their protein expressions. The relative proportion of each MyHC mRNA was significantly positively related to that of its corresponding protein (p<0.01), and MyHC I mRNA proportion was positively correlated with creatine kinase (CK), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) activities (p<0.05). These data suggested that MyHC mRNA transcription can be used to reflect MyHC expression, metabolism property and adaptive plasticity of porcine skeletal muscles, and MyHC mRNA composition could be a molecular index reflecting muscle fiber type characteristics.