A team led by pharmacology professors has discovered a new treatment target of obesity-related diseases, by establishing that Golgi reassembly-stacking protein 55 (GRASP55) of Golgi complex participates in intracellular fat absorption.

Professors Kim Ji-yoon of the Department of Pharmacology at the Catholic University of Korea College of Medicine, Professor Lee Min-goo of the Yonsei University College of Medicine, co-headed the research and presented a new therapeutic target for diseases related to obesity.

Professors Lee Min-goo (left) of the Yonsei University College of Medicine, and Kim Ji-yoon of the Catholic University of Korea College of Medicine

The Golgi complex is an organelle composed of a stack of small flat sacs formed by membranes inside the cell's cytoplasm.

The research team said the component plays a vital role in processing proteins for secretion or wrapping up them for storing. Despite the critical role it plays in intracellular transportation of proteins, researchers have made little efforts to investigate the molecular mechanism of lipid transportation via target Golgi complex.

The joint research team used the gene manipulation technology to breed the mice without the GRASP55 gene and observed its phenotype. GRASP55-lacking mice had problems in intestinal lipid absorption processes, which led the mice to lose their body fat. Also, the mice have shown resistance to weight gain after a high-fat diet.

The research team has confirmed the GRASP55 as the cause of the phenotype through its molecular biology experiment.

According to the study, GRASP55 was involved in the transport of adipose triacylglycerol lipase and monoacylglycerol lipase, which supply fat sources to chylomicron by degrading the lipid droplet in the intestinal cell, to Golgi complex, the team said.

Besides, another experiment that used the model with GRASP55-removed common fruit fly has shown the same result of the study conducted on mice.

As a result of this study, the role and importance of the Golgi complex in regulating intracellular lipids was confirmed, which has provided new treatment targets for obesity-related diseases, it said.

A diagram of lipid absorption mechanism of Golgi complex without the Golgi reassembly-stacking protein 55 (GRASP55)

The significance of the study conducted by the two universities weighs significance on discovering the mechanism of lipid absorption by the Golgi complex, which is the first related finding in the world, it said.

"With the new findings of the Golgi complex's lipid absorption mechanism, which has so far been left unnoticed, we were able to reconfirm how various factors influence the lipid absorption process in human bodies," Professor Kim said. "Our research team will conduct follow-up studies on the Golgi complex to learn about various other functions."

The study was published in Nature Communications on March 17 with the support of the National Research Foundation of Korea.

shim531@docdocdoc.co.kr

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