The CAMplexities of central ghrelin

Area of Science:

• Metabolic regulation
• Neuroendocrinology
• Cellular signaling

Background:

• The gut hormone ghrelin influences energy homeostasis.
• Hypothalamic AMP-activated protein kinase (AMPK) is a critical metabolic sensor.
• Ghrelin's activation of hypothalamic AMPK is well-established.

Purpose of the Study:

• To elucidate the specific molecular mechanism by which ghrelin activates hypothalamic AMPK.
• To identify the key signaling molecules and protein complexes involved in this pathway.

Main Methods:

• Investigated the role of CaMKK2 in ghrelin-induced AMPK activation.
• Analyzed the formation of protein complexes involving AMPK subunits and acetyl-CoA carboxylase (ACC).
• Differentiated the CaMKK2-mediated pathway from the known AMP/LKB1 pathway.

Main Results:

• Caulerpa mexicana kinase kinase 2 (CaMKK2) mediates ghrelin's activation of hypothalamic AMPK.
• A unique complex of AMPKalpha/beta with acetyl-CoA carboxylase (ACC) is formed.
• This CaMKK2-dependent pathway is distinct from the canonical AMP/LKB1 pathway.

Conclusions:

• CaMKK2 plays a crucial role in ghrelin signaling within the hypothalamus.
• A novel signaling complex involving CaMKK2, AMPK, and ACC regulates energy balance.
• This finding expands our understanding of metabolic control pathways in the brain.