Oral Presentation 25th Annual Lorne Proteomics Symposium 2020

Caveolae formation alters intracellular organelle composition and function (#10)

Harley Robinson 1 2 , Jeffrey Molendijk 1 , Mriga Dutt 1 , Alok Shah 1 , Ahmed Mohamed 1 , Leonard Foster 3 , Michelle Hill 1 4
  1. QIMRBerghofer, Herston, QLD, Australia
  2. Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
  3. Michael Smith Laboratories, University of British Colombia, Vancouver, BC, Canada
  4. UQ Diamantina Institute , Brisbane, QLD, Australia

Abnormal expression of caveolae proteins, Caveolin-1 (CAV1) and Cavin-1 (CAVIN1), are linked with tumour progression, lipodystrophy, neurodegeneration and cardiac diseases. While these proteins are co-expressed and co-localized to the plasma membrane in healthy conditions, their dysregulation has been found to alter individual organelle content in some of the aforementioned conditions. Here, we assess the roles of CAV1 and CAVIN1 in regulating organelle content using the PC3 cell line which recapitulates the CAV1+ CAVIN1- expression in advanced prostate cancer. We previously reported ectopic expression of CAVIN1 in PC3 cells reduces oncogenicity, alters exosomal content and cholesterol distributions. As CAVIN1 remains at the plasma membrane in PC3-CAVIN1 cells, we hypothesized organelle remodelling as a mechanism for CAVIN1 in regulating PC3 cell aggressiveness. Using our integrated Protein and Lipid Organelle Profiling (iPLOP) method, we assessed the organelle membrane composition of the aggressive PC3 (non-caveolar) and tumour suppressed PC3-CAVIN1 (caveolae forming) cells. From the proteomics data, sucrose gradient profiles of 5 organelles (mitochondria, endoplasmic reticulum, lysosome, multivesicular bodies and endosomes) were defined based on 5-10 marker proteins. The lipidome of organelles were then mapped by matching lipidomics profiles. This analysis revealed striking changes in the composition of the mitochondria and endoplasmic reticulum. Specifically, we identified enrichment in long unsaturated lipid species in the mitochondrial membranes in the aggressive PC3 cells, corresponding to localization of various proteins relating to energy production, apoptosis and autophagy. Furthermore, iPLOP analysis reveal potential organelle remodelling mechanisms through lipid and protein translocation between organelles. Future work will validate these discovery data using orthogonal methods.