Nutritional, hormonal, and depot-dependent regulation of the expression of the small GTPase Rab18 in rodent adipose tissue.

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

• Level A · Stronger Clinical Evidence
• Level B · Emerging clinical evidence with positive signals
• Level C · Early human research exploring benefits
• Level D · Scientific groundwork from lab and animal studies
• Emerging · Emerging topic under active research

Abstract (original English)

There is increasing evidence that proteins associated with lipid droplets (LDs) play a key role in the coordination of lipid storage and mobilization in adipocytes. The small GTPase, RAB18, has been recently identified as a novel component of the protein coat of LDs and proposed to play a role in both β-adrenergic stimulation of lipolysis and insulin-induced lipogenesis in 3T3-L1 adipocytes. In order to better understand the role of Rab18 in the regulation of lipid metabolism in adipocytes, we evaluated the effects of age, fat location, metabolic status, and hormonal milieu on Rab18 expression in rodent white adipose tissue (WAT). Rab18 mRNA was undetectable at postnatal day 15 (P15), but reached adult levels by P45, in both male and female rats. In adult rats, Rab18 immunolocalized around LDs, as well as within the cytoplasm of mature adipocytes. A weak Rab18 signal was also detected in the stromal-vascular fraction of WAT. In mice, fasting significantly increased, though with a distinct time-course pattern, Rab18 mRNA and protein levels in visceral and subcutaneous WAT. The expression of Rab18 was also increased in visceral and subcutaneous WAT of obese mice (diet-induced, ob/ob, and New Zealand obese mice) compared with lean controls. Rab18 expression in rats was unaltered by castration, adrenalectomy, or GH deficiency but was increased by hypophysectomy, as well as hypothyr

Evidence level

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

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