Subcutaneous Fat Shows Higher Thyroid Hormone Receptor‐α1 Gene Expression Than Omental Fat

Abstract

The aims of this work were to evaluate thyroid hormone receptor‐α (TRα), TRα1, and TRα2 mRNA gene expression and TRα1:TRα2 ratio, identified as candidate factors for explaining regional differences between human adipose tissue depots. TRα, TRα1, and TRα2 mRNA levels, and the gene expressions of arginine–serine‐rich, splicing factor 2 (SF2), heterogeneous nuclear ribonucleoprotein H1 (hnRNP H1), heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), and Spot 14 (S14) were evaluated in 76 paired adipose tissue samples obtained from a population of 38 women who varied widely in terms of obesity and body fat distribution. Gene expression for these factors was also studied in stromal‐vascular cells (SVCs) and mature adipocytes (MAs) from eight paired fat depots. TRα gene and TRα1 mRNA expression were increased 1.46‐fold (P = 0.006) and 1.80‐fold (P < 0.0001), respectively, in subcutaneous (SC) vs. visceral fat. These differences in gene expression levels were most significant in the obese group, in which the TRα1:TRα2 ratio was 2.24‐fold (P < 0.0001) higher in SC vs. visceral fat. S14 gene expression was also increased by 2.42‐fold (P < 0.0001) and correlated significantly with TRα and TRα1 gene expression and with the TRα1:TRα2 ratio. In agreement with these findings, hnRNP A1:SF2 ratio was decreased by 1.39‐fold (P = 0.001). TRα and S14 levels were 2.1‐fold (P < 0.0001) and 112.4‐fold (P < 0.0001), respectively, higher in MAs than in SVCs from both fat depots. In summary, genes for TR‐α, their upstream regulators, and downstream effectors were differentially expressed in SC vs. omental (OM) adipose tissue. Our findings suggest that TRα1 could contribute to SC adipose tissue expandability in obese subjects.

Mouse Betaine-Homocysteine S-Methyltransferase Deficiency Reduces Body Fat via Increasing Energy Expenditure and Impairing Lipid Synthesis and Enhancing Glucose Oxidation in White Adipose Tissue

“…GWAT is considered to be the "pure WAT," whereas IWAT is a "convertible WAT" that may convert to BAT (31). Compared with visceral fat, subcutaneous fat cells express more thyroid hormone receptors (32) and mitochondrial Ucp1 (33,34), have more efficient insulin signaling and Glut4 (35), and are more responsive to Ppar␥ thiazolidinedione ligand (36,37). When subcutaneous fat was transplanted into the visceral cavity of mice, it reduced body weight and fat mass and enhanced insulin and glucose sensitivities (38), suggesting an intrinsic difference between the two fat pads.…”

Mapping, expression and regulation of the TRα gene in porcine adipose tissue

“…Thyroid hormone exerts pleiotropic effects through modulation of gene expression by specific nuclear receptors (TR). TRa plays a central role in mediating the action of thyroid hormone and has been implicated as a major factor in the regulation of the development and function of adipose tissue (Liu et al, 2003;Jiang et al, 2004;Ortega et al, 2009;Mishra et al, 2010). Using the IMpRH panel, we first mapped the TRa gene to porcine chromosome 12.…”

“…Mammals have two principal TR isoforms (TRa and TRβ); each of them gives rise to multiple isoforms via alternate splicing or alternate start codon usage (Munoz and Bernal, 1997). Recently studies have shown that TRα isoform is predominantly expressed in adipocytes and plays a pivotal role in mediating the action of thyroid hormone in adipocytes (Ying et al, 2007;Pelletier et al, 2008;Ortega et al, 2009). Although TRa has been implicated as a major factor in the regulation of fat deposition, little is known about the age-related changes of TRa gene expression in porcine adipose tissue; there is also a lack of information on breed differences.…”

Efeito in vitro da triiodotironina sob o potencial osteogênico reduzido de células-tronco mesenquimais do tecido adiposo de ratas ovariectomizadas e com osteoporose

“…O efeito positivo da T3 na diferenciação osteogê-nica tem sido pesquisado nas CTM-MO de ratas jovens e saudáveis (18). Em CTM do tecido adiposo, tanto subcutâneo quanto visceral, foi comprovada a presença de receptores para os hormônios tireoidianos (19). Mas o que se sabe é que a tiroxina (T4) aumenta a síntese de IGF em culturas de CTM-TA de suínos, favorecendo a adipogênese (20).…”