Expression and distribution of acyl-CoA thioesterases in the white adipose tissue of rats

Abstract

Acyl-CoA thioesterases (Acots) are enzymes that catalyze the hydrolysis of fatty acyl-CoAs to free fatty acids and coenzyme A, and have the potential to regulate the intracellular levels of these molecules. In this study, we show that a cytosolic isoform, Acot1, is expressed and distributed in immature adipocytes located in the perivascular region of the white adipose tissue (WAT) of rats. Immunoblot analyses detected Acot1 in all of the WATs examined, while immunohistochemistry revealed positively stained layered structures surrounding the adventitia of blood vessels in the subcutaneous WAT. When the subcutaneous WAT was digested with collagenase and centrifuged, Acot1 was recovered in the stromal vascular fraction (SVF), and not in the large mature adipocytes. In the SVF, undigested cells attached to short tubular fragments of blood vessels showed positive immunostaining, as well as a proportion of the dispersed cells. These fibroblast-like cells contained fine particulate lipid droplets, stained by oil-red O dye, in their cytoplasm, or expressed fatty acid-binding protein 4, an adipocyte marker. After induction of adipocyte differentiation following a 15-day preculture without insulin, the dedifferentiated cells showed increased Acot1 expression with a diffuse distribution throughout the cytosol. These findings suggest that Acot1 expression is transiently upregulated at an early stage of adipocyte maturation, possibly to maintain cytosolic acyl-CoAs below a certain level until the cells acquire their full capability for fat storage.

Transcriptome Analysis of Testis from HFD-Induced Obese Rats (Rattus norvigicus) Indicated Predisposition for Male Infertility

“…Seven DEGs were categorized under the pathway of lipid metabolic processes. Acyl-CoA thioesterases (Acots) are a group of enzymes that catalyze the hydrolysis of fatty acyl-CoA thioesters to the corresponding free fatty acids and coenzyme A [56]. In the present study, Acyl-CoA thioesterase 4(ACOT4) and Acyl-coA oxidase-like (ACOXL) expression were downregulated in the testis of obese rats with an O/C value of −10.75 and −4.72, respectively.…”

The Histochem Cell Biol conspectus: the year 2013 in review

“…In brown fat adipocytes, Acot1 has been proposed to regulate the levels of cytosolic acyl-CoAs during cell maturation. Ohtomo et al (2013) investigated whether similar regulation may occur in other cell types that utilize fatty acids, specifically white fat adipocytes. Thus, they examined the expression and distribution of Acot1 in white adipose tissue from rats, and following cellular differentiation in culture.…”

Identification of Acyl-CoA Thioesterase in Mouse Mesenteric Lymph Nodes

“…[8][9][10][11] However, ACOT7 has enzyme activity two orders of magnitude higher than ACOT1 and ACOT2, and its expression is prominent in neurons of the central and peripheral nervous systems. [12][13][14] Thus, ACOT7 may have a role in cellular events other than energy metabolism, as the overexpression of ACOT7 in a macrophage cell line modified the production of prostaglandins.15) Recently, we examined the expression of ACOTs in fat tissues of rats 16,17) and unexpectedly found a significant level of acyl-CoA thioesterase activity in the mesenteric lymph nodes (MLNs) that contaminated visceral fat preparations. Here, we report that ACOT7 is expressed in mouse MLNs and is responsible for the majority of acyl-CoA thioesterase activity present in this immune tissue.…”