A molecular casting net triggers hormone release

4 Mar 2015

New insights into the biological process that controls the release of hormones and neurotransmitters has been uncovered by a study at QBI.

Researchers at UQ’s Queensland Brain Institute and Institute for Molecular Bioscience found the release of hormones from the secreting cells is precisely regulated by a molecular “casting net”.

Study leader Professor Frederic Meunier from QBI said the team found that there is a network of a cytoskeletal protein called actin and myosin acting as a “casting net” that captures vesicles, pulling them towards their docking site to release all of their contents at the same time.

“Our bodies rely on the release of hormones and neurotransmitters, which are stored in vesicles, and in this research we unravelled the molecular mechanism underpinning the approach of the vesicles toward their secretion sites,” Professor Meunier said.

“It’s a very efficient process where all of the vesicles are caught and brought together in a synchronised manner, so in a healthy system the hormonal’s message is controlled and strong.

“Previously it was thought that vesicles were released one by one, but instead this molecular casting net brings them all together when they’re stimulated.”

QBI’s Dr Andreas Papadopulos, first author of the study, said when this crucial system malfunctions it can result in the release of either too few or too many hormones such as dopamine and adrenaline.

“While the underlying research is fundamental to our understanding of how hormones are secreted, deficiency in this casting net can lead to over-release associated with pheochromocytoma, a neuroendocrine tumour,” Dr Papadopulos said.

“Understanding this mechanism is critical for keeping the communication between different parts of your body working.

“This new understanding now allows us to begin looking at ways to treat the root cause of conditions that result from this process going wrong.”

The study was performed with bovine adrenal cells, using state-of-the-art microscopy allowing visual monitoring of hormone-containing vesicles in real time.

“Bovine cells are very similar to ours, but we share the same fundamental physiology, so the processes work the same way,” Dr Papadopulos said.

UQ collaborated with Flinders University on the paper.

The study was supported by the National Health and Medical Research Council, Australian Research Council, and the Kids Cancer Project of the Oncology Children’s Foundation and findings appear in Nature Communications.