Effects Of Lipid Droplets In Regulating The Morphology And Functions Of Other Organelles In Yeast Saccharomyces Cerevisiae

Organelles contact and collaborate to accomplish the material transfer and signal communication.Lipid droplets(LDs)are the main neutral lipid storage organelles,but their functions are far more than that.LDs can interact with various organelles including the endoplasmic reticulum,mitochondria,peroxisomes,lysosomes/vacuoles,and nucleus,to jointly achieve functions such as lipid metabolism,membrane transport,and signal transduction.In this study,we constructed neutral lipid synthesis defect strains(dga1Δlro1Δ,are1Δare2Δ)and lipid droplets deletion strain(dga1Δlro1Δare1Δare2Δ)to explore how they affect the morphology,quantity,and function of intracellular organelles.We found that the lack of the certain types of neutral lipids or lipid droplets could change the morphology of vacuoles,mitochondria,nucleus,and also affected the quantity of peroxisomes.Further functional analysis showed that the lack of neutral lipids or lipid droplets significantly affected the degradation of vacuolar membrane protein Vph1,generation of autophagosome,mitochondria aerobic breathing,and clearance of intracellular ROS.To further analyze the direct reason for these phenotypes.We constructed triglyceride hydrolysis deficient strain(tgl3Δtgl4Δtgl5Δ)and sterol ester hydrolysis deficient strain(tgl1Δyeh1Δyeh2Δ).To verify neutral lipid itself,neutral lipid hydrolysis products and the lipid droplet surface protein which is the key factor resulting in the defects of vacuole and mitochondria,we further constructed a mutant library of lipid droplet surface protein as well as labeling of vacuole and mitochondria with the fluorescent protein.Results showed that only several lipid droplet’s surface proteins affect the morphology of vacuole and mitochondria,while most of them don’t.The study of interaction mechanism and function between LDs and intracellular organelles will not only broaden our knowledge of lipid droplet biology,but also help us further understand the pathogenesis of metabolic diseases.