OPA1 processing controls mitochondrial fusion and is regulated by mRNA splicing, membrane potential, and Yme1L.

Abstract

OPA1, a dynamin-related guanosine triphosphatase mutated in dominant optic atrophy, is required for the fusion of mitochondria. Proteolytic cleavage by the mitochondrial processing peptidase generates long isoforms from eight messenger RNA (mRNA) splice forms, whereas further cleavages at protease sites S1 and S2 generate short forms. Using OPA1-null cells, we developed a cellular system to study how individual OPA1 splice forms function in mitochondrial fusion. Only mRNA splice forms that generate a long isoform in addition to one or more short isoforms support substantial mitochondrial fusion activity. On their own, long and short OPA1 isoforms have little activity, but, when coexpressed, they functionally complement each other. Loss of mitochondrial membrane potential destabilizes the long isoforms and enhances the cleavage of OPA1 at S1 but not S2. Cleavage at S2 is regulated by the i-AAA protease Yme1L. Our results suggest that mammalian cells have multiple pathways to control mitochondrial fusion through regulation of the spectrum of OPA1 isoforms.

• Authors: Zhiyin Song, Hsiuchen Chen, Maja Fiket, Christiane Alexander, David C Chan
• Journal: The Journal of cell biology (J Cell Biol) Vol. 178 Issue 5 Pg. 749-55 (Aug 27 2007) ISSN: 0021-9525 [Print] United States
• PMID: 17709429 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Protein Isoforms
• RNA, Messenger
• Metalloendopeptidases
• GTP Phosphohydrolases
• OPA1 protein, human

Topics

• Animals
• Cells, Cultured
• Fibroblasts (cytology, metabolism)
• GTP Phosphohydrolases (genetics, metabolism)
• Humans
• Membrane Fusion (physiology)
• Membrane Potentials (physiology)
• Metalloendopeptidases (genetics, metabolism)
• Mice
• Mitochondria (metabolism)
• Protein Isoforms (genetics, metabolism)
• RNA Splicing
• RNA, Messenger (genetics, metabolism)