Mumbai: A team of researchers from the Indian Institute of Technology Bombay and the Tata Institute of Fundamental Research in Mumbai discovered that lipid droplets fuse with or attach to the ER inside the cells of the liver after an animal consumes food, as well as during bacterial infection.
The molecules that mediate this contact are identified in this study, which was published in the Proceedings of the National Academy of Sciences. These findings could aid future research aimed at lowering lipid levels in the blood, a topic of interest because high lipid levels can lead to obesity, diabetes, and cardiac problems.
A typical human cell is filled with cytoplasm and contains a nucleus as well as several other organelles. Lipid droplets—vesicles or sacs made of lipid molecules, similar to oil droplets—are suspended within the cytoplasm. The endoplasmic reticulum (ER) is an interconnected web of tubular network that surrounds the cell's nucleus.
How is the lipid released into the blood from the liver?
After one consumes food, glucose levels in the blood rise, thus boosting insulin production. Insulin activates a protein called Kinesin to bind to lipid droplets. Kinesin acts as a railway engine and chugs the lipid droplets to the vicinity of the ER on molecular tracks made of protein filaments. The lipid droplet then delivers its load of lipids to the ER and can, in turn, also receive a cargo of antibacterial proteins from the ER.
When binding between cell organelles fails, it can result in diseases like Alzheimer's and Parkinson's. The researchers hope that their study into the binding mechanism between lipid droplets and ER will aid in the understanding of such diseases.
It is also possible to disrupt the binding of lipid droplets. The researchers are currently working to prevent Kinesin from binding to lipid droplets within the liver. The constraint is that it must be done without interfering with Kinesin binding to other organelles (non-lipid droplets).