Cytosolic signaling protein Ecsit also localizes to mitochondria where it interacts with chaperone NDUFAF1 and functions in complex I assembly

Rutger O. Vogel; Rolf J.R.J. Janssen; Mariël A.M. van den Brand; Cindy E.J. Dieteren; Sjoerd Verkaart; Werner J.H. Koopman; Peter H.G.M. Willems; Wendy Pluk; Lambert P.W.J. van den Heuvel; Jan A.M. Smeitink; Leo G.J. Nijtmans

doi:10.1101/gad.408407

Cytosolic signaling protein Ecsit also localizes to mitochondria where it interacts with chaperone NDUFAF1 and functions in complex I assembly

¹ Department of Paediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Nijmegen Medical Centre, Nijmegen 6500 HB, The Netherlands;
² Department of Membrane Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen 6500 HB, The Netherlands;
³ Nijmegen Proteomics Facility, Radboud University Nijmegen Medical Centre, Nijmegen 6500 HB, The Netherlands

Abstract

Ecsit is a cytosolic adaptor protein essential for inflammatory response and embryonic development via the Toll-like and BMP (bone morphogenetic protein) signal transduction pathways, respectively. Here, we demonstrate a mitochondrial function for Ecsit (an evolutionary conserved signaling intermediate in Toll pathways) in the assembly of mitochondrial complex I (NADH:ubiquinone oxidoreductase). An N-terminal targeting signal directs Ecsit to mitochondria, where it interacts with assembly chaperone NDUFAF1 in 500- to 850-kDa complexes as demonstrated by affinity purification and vice versa RNA interference (RNAi) knockdowns. In addition, Ecsit knockdown results in severely impaired complex I assembly and disturbed mitochondrial function. These findings support a function for Ecsit in the assembly or stability of mitochondrial complex I, possibly linking assembly of oxidative phosphorylation complexes to inflammatory response and embryonic development.

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Footnotes

↵4 Corresponding author.

↵4 E-MAIL l.nijtmans{at}cukz.umcn.nl; FAX 31-24-3618900.
Supplemental material is available at http://www.genesdev.org.
Article is online at http://www.genesdev.org/cgi/doi/10.1101/gad.408407
- Received September 5, 2006.
- Accepted January 22, 2007.