| Autor: |
De Maio A; Department of Surgery, Division of Trauma, Critical Care, Burns and Acute Care Surgery, School of Medicine, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA, 92093-0739, USA. ademaio@ucsd.edu.; Department of Neurosciences, Division of Trauma, Critical Care, Burns and Acute, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA. ademaio@ucsd.edu., Cauvi DM; Department of Surgery, Division of Trauma, Critical Care, Burns and Acute Care Surgery, School of Medicine, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA, 92093-0739, USA., Capone R; Department of Surgery, Division of Trauma, Critical Care, Burns and Acute Care Surgery, School of Medicine, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA, 92093-0739, USA., Bello I; Department of Surgery, Division of Trauma, Critical Care, Burns and Acute Care Surgery, School of Medicine, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA, 92093-0739, USA., Egberts WV; Department of Biomolecular Chemistry, Institute for Molecules and Materials and Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands., Arispe N; Department of Anatomy, Physiology and Genetics, School of Medicine, Uniformed Services University, Bethesda, MD, 20814, USA., Boelens W; Department of Anatomy, Physiology and Genetics, School of Medicine, Uniformed Services University, Bethesda, MD, 20814, USA. |
| Abstrakt: |
Increasing evidence shows that heat shock proteins (hsp) escape the cytosol gaining access to the extracellular environment, acting as signaling agents. Since the majority of these proteins lack the information necessary for their export via the classical secretory pathway, attention has been focused on alternative releasing mechanisms. Crossing the plasma membrane is a major obstacle to the secretion of a cytosolic protein into the extracellular milieu. Several mechanisms have been proposed, including direct interaction with the plasma membrane or their release within extracellular vesicles (ECV). HSPB1 (Hsp27), which belongs to the small hsp family, was detected within the membrane of ECV released from stressed HepG2 cells. To further investigate this finding, we studied the interaction of HSPB1 with lipid membranes using liposomes. We found that HSPB1 interacted with liposomes made of palmitoyl oleoyl phosphatidylserine (POPS), palmitoyl oleoyl phosphatidylcholine (POPC), and palmitoyl oleoyl phosphatidylglycerol (POPG), with different characteristics. Another member of the small hsp family, HSPB5 (αB-crystallin), has also been detected within ECV released from HeLa cells transfected with this gene. This protein was found to interact with liposomes as well, but differently than HSPB1. To address the regions interacting with the membrane, proteoliposomes were digested with proteinase K and the protected domains within the liposomes were identified by mass spectroscopy. We observed that large parts of HSPB1 and HSPB5 were embedded within the liposomes, particularly the alpha-crystallin domain. These observations suggest that the interaction with lipid membranes may be part of the mechanisms of export of these proteins. |
Full text from SpringerLink