Immune synapses: mitochondrial morphology matters.

Proper positioning of mitochondria is critical for cellular function. Mitochondria localization close to synapses regulates signalling at neuronal and immune synapses (ISs). Vice versa, synapses influence activity, motility and the fusion/fission balance of close-by mitochondria. In this issue of The EMBO Journal, Baixauli et al (2011) identify a role for the mitochondrial fission factor dynamin-related protein 1 (DRP1) at the IS. DRP1 not only controls mitochondrial fission but also mitochondrial positioning to the IS, thereby modulating IS formation and downstream signalling. Main functions of mitochondria are energy supply, Ca buffering, supply of metabolites and the sequestration of apoptotic factors (Hollenbeck and Saxton, 2005; Chan, 2006). It is not surprising that mitochondria thereby regulate a majority of cellular processes. In a simple model,