Multifaceted mitochondria: moving mitochondrial science beyond function and dysfunction

Mitochondria have cell-type specific phenotypes, perform dozens of interconnected functions and undergo dynamic and often reversible physiological recalibrations. Given their multifunctional and malleable nature, the frequently used terms ‘mitochondrial function’ and ‘mitochondrial dysfunction’ are misleading misnomers that fail to capture the complexity of mitochondrial biology. To increase the conceptual and experimental specificity in mitochondrial science, we propose a terminology system that distinguishes between (1) cell-dependent properties, (2) molecular features, (3) activities, (4) functions and (5) behaviours. A hierarchical terminology system that accurately captures the multifaceted nature of mitochondria will achieve three important outcomes. It will convey a more holistic picture of mitochondria as we teach the next generations of mitochondrial biologists, maximize progress in the rapidly expanding field of mitochondrial science, and also facilitate synergy with other disciplines. Improving specificity in the language around mitochondrial science is a step towards refining our understanding of the mechanisms by which this unique family of organelles contributes to cellular and organismal health. The authors of this Perspective argue that the commonly used terms ‘mitochondrial function’ and ‘mitochondrial dysfunction’ do not do justice to the diverse mitochondrial features, activities, functions and behaviours within cells, and thus call for the field to adopt more specific terminology in the context of mitochondrial biology.