• Changes in mitochondrial PLIN3 and PLIN5 protein content in rat skeletal muscle following acute contraction and endurance training

      Ramos, Sofhia; Applied Health Sciences Program (Brock University, 2014-11-03)
      Surrounding lipid droplets in skeletal muscle are the perilipin (PLIN2-5) family of proteins, regulating lipid droplet metabolism. During exercise lipid droplets provide fatty acids to the mitochondria for oxidation while increasing their proximity to each other. Whether PLIN3 and PLIN5 associate with mitochondria following contraction has not been examined. To determine whether contraction altered mitochondrial PLIN3 and PLIN5 content, sedentary and endurance trained rats underwent acute contraction. The main outcomes are; 1) mitochondrial PLIN3 content is unaltered while mitochondrial PLIN5 content is increased following an acute contraction 2) mitochondrial PLIN3 content is higher in endurance trained rats when compared to sedentary and mitochondrial PLIN5 content is similar in both conditions 3) only PLIN5 mitochondrial content is increased similarly in both groups following acute contraction. This work highlights the dynamics of these two PLIN proteins, which may have roles not only on the lipid droplet but also on the mitochondria.
    • Intra-mitochondrial location of the skeletal muscle perilipin 3 and 5 proteins at rest and following electrically stimulated contraction

      Hunter, Mackenzie; Applied Health Sciences Program
      PLIN3 and PLIN5 have been shown to localize to skeletal muscle mitochondria. Hypotheses state that these PLINs could facilitate lipid droplet-mitochondrial interactions, however, this would presumably require that they would localize to the outer mitochondrial membrane (OMM). The purpose of this study was to sub-fractionate skeletal muscle mitochondria at rest and following contraction to determine the precise intra-mitochondrial localization of PLIN3 and PLIN5. At rest, PLIN5 was primarily found in the OMM/intermembrane space (IMS) fraction, however, following contraction there was a redistribution of PLIN5 protein content towards the mitoplasts. PLIN3 protein content localized to the OMM/IMS at rest and was unchanged with stimulation. Co-immunoprecipitation found PLIN5 associated with both ACSL1 and CPT I at rest and following contraction while PLIN3 only associated with ACSL1. CPT I and II also associate, allowing for a link between the two membranes that may help explain the shift of PLIN5 to the mitoplast following contraction.