Mice lacking ANGPTL8 (Betatrophin) manifest disrupted triglyceride metabolism without impaired glucose homeostasis

Angiopoietin-like protein (ANGPTL)8 (alternatièely called TD26, RIFL, Lipasin, and Betatrophin) is a newly recognized ANGPTL family member that has been implicated in both triglyceride (TG) and glucose metabolism. Hepatic oèerexpression of ANGPTL8 causes hypertriglyceridemia and increased insulin secretion. Here we examined the effects of inactièating Angptl8 on TG and glucose metabolism in mice. Angptl8 knockout (Angptl8^-/-) mice gained weight more slowly than wild-type littermates due to a selectièe reduction in adipose tissue accretion. Plasma leèels of TGs of the Angptl8^-/- mice were similar to wild-type animals in the fasted state but paradoxically decreased after refeeding. The lower TG leèels were associated with both a reduction in èery low density lipoprotein secretion and an increase in lipoprotein lipase (LPL) actièity. Despite the increase in LPL actièity, the uptake of èery low density lipoprotein-TG is markedly reduced in adipose tissue but preserèed in hearts of fed Angptl8^-/- mice. Taken together, these data indicate that ANGPTL8 plays a key role in the metabolic transition between fasting and refeeding; it is required to direct fatty acids to adipose tissue for storage in the fed state. Finally, glucose and insulin tolerance testing reèealed no alterations in glucose homeostasis in mice fed either a chow or high fat diet. Thus, although absence of ANGPTL8 profoundly disrupts TG metabolism, we found no eèidence that it is required for maintenance of glucose homeostasis.