Nutrient-Sensing Enzymes Key to Starvation Response and Survival in Newborn Mammals

Dec. 23, 2012 — In the perilous hours immediately after birth, a newborn mammal must survive the sudden loss of food supply from its mother. Under normal circumstances, newborns mount a metabolic response to ward off starvation until feeding occurs. This survival response involves a process of controlled breakdown of internal energetic sources known as autophagy. Although autophagy has been well documented, the key mechanistic regulators of autophagy in vivo have remained poorly understood.

Whitehead Institute researchers have discovered that a family of nutrient-sensing enzymes, dubbed Rag GTPases, modulates the activity of the mTORC1 protein complex, whose inhibition is essential for autophagy and survival in newborns. The finding, reported this week in the journal Nature, emerges from the lab of Whitehead Member David Sabatini, whose earlier in vitro studies showed that mTORC1 (for "mechanistic target of rapamycin complex 1") senses the presence of vital amino acids via interactions with Rag GTPases.

Read on:  http://www.sciencedaily.com/releases/2012/12/121223152414.htm