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- Title
TMEM9B Regulates Endosomal ClC-3 and ClC-4 Transporters.
- Authors
Festa, Margherita; Coppola, Maria Antonietta; Angeli, Elena; Tettey-Matey, Abraham; Giusto, Alice; Mazza, Irene; Gatta, Elena; Barbieri, Raffaella; Picollo, Alessandra; Gavazzo, Paola; Pusch, Michael; Picco, Cristiana; Sbrana, Francesca
- Abstract
The nine-member CLC gene family of Cl− chloride-transporting membrane proteins is divided into plasma membrane-localized Cl− channels and endo-/lysosomal Cl−/H+ antiporters. Accessory proteins have been identified for ClC-K and ClC-2 channels and for the lysosomal ClC-7, but not the other CLCs. Here, we identified TMEM9 Domain Family Member B (TMEM9B), a single-span type I transmembrane protein of unknown function, to strongly interact with the neuronal endosomal ClC-3 and ClC-4 transporters. Co-expression of TMEM9B with ClC-3 or ClC-4 dramatically reduced transporter activity in Xenopus oocytes and transfected HEK cells. For ClC-3, TMEM9B also induced a slow component in the kinetics of the activation time course, suggesting direct interaction. Currents mediated by ClC-7 were hardly affected by TMEM9B, and ClC-1 currents were only slightly reduced, demonstrating specific interaction with ClC-3 and ClC-4. We obtained strong evidence for direct interaction by detecting significant Förster Resonance Energy Transfer (FRET), exploiting fluorescence lifetime microscopy-based (FLIM-FRET) techniques between TMEM9B and ClC-3 and ClC-4, but hardly any FRET with ClC-1 or ClC-7. The discovery of TMEM9B as a novel interaction partner of ClC-3 and ClC-4 might have important implications for the physiological role of these transporters in neuronal endosomal homeostasis and for a better understanding of the pathological mechanisms in CLCN3- and CLCN4-related pathological conditions.
- Subjects
FLUORESCENCE resonance energy transfer; MEMBRANE proteins; GENE families; ENDOSOMES; HOMEOSTASIS
- Publication
Life (2075-1729), 2024, Vol 14, Issue 8, p1034
- ISSN
2075-1729
- Publication type
Article
- DOI
10.3390/life14081034