Membrane fusion mechanisms and applications: assessment of current knowledge

Abstract

Biological membranes are of paramount importance to the life ofthe cell, since they are responsible forthe maintenance of the individuality of the cell itself and its subcellular organelles. Differences between cells and between cellular compartments are maintained by membranes. However, many aspects of living organisms and cells involve membrane fusion, a process which results in the merging of two lipid bilayers in a discrete and localized area and in the redistribution of aqueous contents and bilayer components. Membrane fusion is an ubiquitous and critical event in biological systems. It is a required step for the infectious cycle of enveloped viruses, zygote formation, endocytosis, exocytosis, intracellular traffic, and many other biological processes. This makes membrane fusion a broad area of research which encompasses many scientific disciplines including virology, biochemistry, biophysics and cell biology. In addition, membrane fusion technology is now used as a tool for drug delivery and gene therapy. In spite of its multi-disciplinarity nature, many membrane fusioneventssharecommonmechanisms.Onethereforesees a convergence of different areas of cell biology, virology and developmentalbiology.However,understandingthemolecular events involvedinmembrane fusionprocesses is notaneasy task, since only a minor fraction of the lipids of the two membranes fuse and lipids are too small to be seen by any means, thus makingthis area ofresearchhighlydependenton thedevelopmentofnewtechniquesandmodels.Nevertheless, significantprogresshasbeenachievedduringthelastfewyears by employingdifferentapproaches andvarious biologicaland modelsystems, anditis nowtimely tosurveyrecent developmentsandachievementsinthefield.Withthisobjectiveinmind,