An article from Andreas Brech's project group is the cover story of the July issue of the well reputed journal Traffic (impact factor 5.7). Sanne Stuffers is first author, and the article is entitled "Multivesicular Endosome Biogenesis in the Absence of ESCRTs". Stuffers and co-workers have here used electron microscopy to study the importance of endosomal sorting complex required for transport (ESCRT) proteins in growth factor receptor trafficking.
The authors used small interferring RNA (siRNA) to knock down the expression of all the four ESCRT complexes and monitored how this affected trafficking of epidermal growth factor (EGF) receptors. They found that ESCRT knockdown prevented the trafficking of EGF receptors to lysosomes and instead caused their retention in early endosomes. Surprisingly, even though the ESCRT complexes have been implicated in the biogenesis of multivesicular endosomes (MVEs), a substantial number of MVEs remained even in ESCRT-depleted cells. The authors conclude that even though the ESCRT machinery is crucial for EGF receptor downregulation in lysosomes, MVEs can be formed by alternative mechanisms that are ESCRT independent.
Multivesicular Endosome Biogenesis in the Absence of ESCRTs.
Stuffers S, Sem Wegner C, Stenmark H, Brech A.
Traffic. 2009 Apr 10. [Epub ahead of print]
Andreas Brech's project group: Unit of Cellular Electron Microscopy
Department of Biochemistry
Institute for Cancer Research