RESUMO
The Alpha subunit of the stimulatory guanine nucleotide-binding protein (GNAS) is a complex imprinted gene. The major product of the GNAS gene is the α-subunit of the guanine nucleotide-binding protein (Gas), which plays a key role in multiple signal transduction pathways. Gas is required for the production of the receptor-stimulated intracellular cyclic adenosine monophosphate (cAMP). It has been demonstrated that an increase in the concentration of the intracellular second messenger cAMP promotes apoptosis in different tumor entities. Mutations of GNAS have also been identified in many tumors. This study aimed to investigate the expression pattern and the apoptosis effect in fibroblast cells for porcine GNAS. The results show that GNAS mRNA was detected in a wide range of tissues, especially in the longissimus dorsi muscle and thyroid gland. The developmental pattern of GNAS mRNA in the thyroid gland of Jinhua pigs was then examined; however, there was no significant difference (P > 0.05) among any of the stages. GNAS gene expression was relatively stable in the thyroid gland during the entire growth and development process. The developmental pattern of GNAS mRNA in the longissimus dorsi muscle was significantly different among the various developmental stages (P < 0.01). GNAS mRNA was strongly expressed at 60 days, 90 days, and 150 days after birth, whereas the expression level was very low during the embryo stages. Target RNA interference of GNAS in porcine fibroblast cells leads to lower mRNA expression of Bcl-2, Fas, and Caspase-3, which are recognized as apoptosis related markers.
Assuntos
Fibroblastos/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/genética , Regulação da Expressão Gênica no Desenvolvimento , Músculo Esquelético/metabolismo , RNA Mensageiro/genética , Glândula Tireoide/metabolismo , Fatores Etários , Animais , Apoptose/genética , Caspase 3/genética , Caspase 3/metabolismo , Clonagem Molecular , Embrião de Mamíferos , Fibroblastos/citologia , Subunidades alfa Gs de Proteínas de Ligação ao GTP/antagonistas & inibidores , Subunidades alfa Gs de Proteínas de Ligação ao GTP/classificação , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Músculo Esquelético/crescimento & desenvolvimento , Especificidade de Órgãos , Filogenia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Homologia de Sequência de Aminoácidos , Suínos , Glândula Tireoide/crescimento & desenvolvimento , Receptor fas/genética , Receptor fas/metabolismoRESUMO
Thyroid hormone receptors (TR) are members of the nuclear receptor superfamily. There are at least two TR isoforms, TRα and TRß. The TRα isoform plays a critical role in mediating the action of thyroid hormone in adipose tissue. We mapped the porcine TRα gene to chromosome 12 p11-p13, by using the ImpRH panel. We examined tissue-localization of TRα and determined expression patterns of TRα in porcine adipose tissue with quantitative real-time PCR. TRα was expressed in all tissues, including heart, liver, spleen, stomach, pancreas, brain, small intestine, skeletal muscle, and subcutaneous adipose tissue. In the adipose tissue, the expression of TRα decreased postnatally. Compared to Yorkshire pigs, Jinhua pigs had significantly lower expression levels of TRα gene in the subcutaneous fat tissue. The expression levels of ß2-AR, HSL and ATGL were also significantly lower in Jinhua pigs than in Yorkshire pigs. However, no significant differences in PPARγ and SREBP-1C expression levels were found between Jinhua and Yorkshire pigs. Incubation of porcine adipose tissue explants with high doses of isoproterenol (100 and 1000 nM) significantly increased the expression levels of TRα. We conclude that there is considerable evidence that TRα plays an important role in fat deposition in porcine adipose tissue.