Discovery of Lipid Hormone Ushers in the Age of Lipidomics

The discovery of a lipid hormone that prevents the accumulation of fat in the liver and enhances the body's ability to control glucose levels confirms the importance of lipidomics as a research discipline alongside the well-established fields of genomics and proteomics.

Investigators at the Harvard University School of Public Health (Cambridge, MA, USA) focused on the lipid metabolism in the adipose tissue of a line of mice that had been genetically engineered to lack the lipid chaperones aP2 and mal1. They reported in the September 19, 2008, online issue of the journal Cell that a localized increase in lipid synthesis rendered the adipose tissue of these mice resistant to the deleterious effects of dietary lipid exposure. Systemic lipid profiling led to identification of C16:1n7-palmitoleate as an adipose tissue-derived lipid hormone that strongly stimulated muscle insulin action and suppressed accumulation of fats in the animals' livers. The data revealed a lipid-mediated endocrine network and demonstrated that adipose tissue used lipokines such as C16:1n7-palmitoleate to communicate with distant organs and regulate systemic metabolic homeostasis.

Senior author Dr. Gokhan Hotamisligil, professor of genetics at the Harvard University School of Public Health, said, "This hormone, a member of a new group called lipokines, is the first example of a class made out of fatty acids. All evidence is pointing that it is coming from fat cells.”

The lipokine hormone may be directly linked to the side effects of obesity in humans. As body fat increases, less palmitoleate is produced, so in obese people, the beneficial functions of this hormone in controlling blood sugar levels and preventing fat accumulating in the liver are diminished. "When you need it the most, you produce the least,” said Dr. Hotamisligil.

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