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Stark RJ, Nguyen HN, Bacon MK, Rohrbough JC, Choi H, Lamb FS. Chloride Channel-3 (ClC-3) Modifies the Trafficking of Leucine-Rich Repeat-Containing 8A (LRRC8A) Anion Channels. J Membr Biol 2022; 256:125-135. [PMID: 36322172 PMCID: PMC10085862 DOI: 10.1007/s00232-022-00271-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/16/2022] [Indexed: 11/07/2022]
Abstract
Chloride channel-3 (ClC-3) Cl-/H+ antiporters and leucine-rich repeat-containing 8 (LRRC8) family anion channels have both been associated with volume-regulated anion currents (VRACs). VRACs are often altered in ClC-3 null cells but are absent in LRRC8A null cells. To explore the relationship between ClC-3, LRRC8A, and VRAC we localized tagged proteins in human epithelial kidney (HEK293) cells using multimodal microscopy. Expression of ClC-3-GFP induced large multivesicular bodies (MVBs) with ClC-3 in the delimiting membrane. LRRC8A-RFP localized to the plasma membrane and to small cytoplasmic vesicles. Co-expression demonstrated co-localization in small, highly mobile cytoplasmic vesicles that associated with the early endosomal marker Rab5A. However, most of the small LRRC8A-positive vesicles were constrained within large MVBs with abundant ClC-3 in the delimiting membrane. Dominant negative (S34A) Rab5A prevented ClC-3 overexpression from creating enlarged MVBs, while constitutively active (Q79L) Rab5A enhanced this phenotype. Thus, ClC-3 and LRRC8A are endocytosed together but independently sorted in Rab5A MVBs. Subsequently, LRRC8A-labeled vesicles were sorted to MVBs labeled by Rab27A and B exosomal compartment markers, but not to Rab11 recycling endosomes. VRAC currents were significantly larger in ClC-3 null HEK293 cells. This work demonstrates dependence of LRRC8A trafficking on ClC-3 which may explain the association between ClC-3 and VRACs.
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Affiliation(s)
- Ryan J Stark
- Department of Pediatrics, Vanderbilt University Medical Center, 2215 Garland Avenue, Light Hall-1055D, Nashville, TN, 37232-3122v, USA
| | - Hong N Nguyen
- Department of Pediatrics, Vanderbilt University Medical Center, 2215 Garland Avenue, Light Hall-1055D, Nashville, TN, 37232-3122v, USA
| | - Matthew K Bacon
- Department of Pediatrics, University of Kentucky, Lexington, KY, 40536, USA
| | - Jeffrey C Rohrbough
- Department of Pediatrics, Vanderbilt University Medical Center, 2215 Garland Avenue, Light Hall-1055D, Nashville, TN, 37232-3122v, USA
| | - Hyehun Choi
- Department of Pediatrics, Vanderbilt University Medical Center, 2215 Garland Avenue, Light Hall-1055D, Nashville, TN, 37232-3122v, USA
| | - Fred S Lamb
- Department of Pediatrics, Vanderbilt University Medical Center, 2215 Garland Avenue, Light Hall-1055D, Nashville, TN, 37232-3122v, USA.
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