1
|
Paredes JM, Idilli AI, Mariotti L, Losi G, Arslanbaeva LR, Sato SS, Artoni P, Szczurkowska J, Cancedda L, Ratto GM, Carmignoto G, Arosio D. Synchronous Bioimaging of Intracellular pH and Chloride Based on LSS Fluorescent Protein. ACS Chem Biol 2016; 11:1652-60. [PMID: 27031242 DOI: 10.1021/acschembio.6b00103] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Ion homeostasis regulates critical physiological processes in the living cell. Intracellular chloride concentration not only contributes in setting the membrane potential of quiescent cells but it also plays a role in modulating the dynamic voltage changes during network activity. Dynamic chloride imaging demands new tools, allowing faster acquisition rates and correct accounting of concomitant pH changes. Joining a long-Stokes-shift red-fluorescent protein to a GFP variant with high sensitivity to pH and chloride, we obtained LSSmClopHensor, a genetically encoded fluorescent biosensor optimized for the simultaneous chloride and pH imaging and requiring only two excitation wavelengths (458 and 488 nm). LSSmClopHensor allowed us to monitor the dynamic changes of intracellular pH and chloride concentration during seizure like discharges in neocortical brain slices. Only cells with tightly controlled resting potential revealed a narrow distribution of chloride concentration peaking at about 5 and 8 mM, in neocortical neurons and SK-N-SH cells, respectively. We thus showed that LSSmClopHensor represents a new versatile tool for studying the dynamics of chloride and proton concentration in living systems.
Collapse
Affiliation(s)
- Jose M. Paredes
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- Bruno Kessler Foundation, Via
Sommarive 18, 38123 Trento, Italy
| | - Aurora I. Idilli
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
| | - Letizia Mariotti
- Neuroscience Institute, CNR, Viale
G. Colombo 3, 35121 Padova, Italy
| | - Gabriele Losi
- Neuroscience Institute, CNR, Viale
G. Colombo 3, 35121 Padova, Italy
| | - Lyaysan R. Arslanbaeva
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- CIBIO, University of Trento, Via delle Regole 101, 38123 Trento, Italy
| | | | | | | | | | - Gian Michele Ratto
- Nanoscience Institute, CNR, Pisa, Italy
- Scuola Normale Superiore, Pisa, Italy
| | | | - Daniele Arosio
- Institute of Biophysics, CNR, Via
alla Cascata 56/C, 38123 Trento, Italy
- CIBIO, University of Trento, Via delle Regole 101, 38123 Trento, Italy
| |
Collapse
|
2
|
Ruppersburg CC, Hartzell HC. The Ca2+-activated Cl- channel ANO1/TMEM16A regulates primary ciliogenesis. Mol Biol Cell 2014; 25:1793-807. [PMID: 24694595 PMCID: PMC4038505 DOI: 10.1091/mbc.e13-10-0599] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca2+-activated Cl− channel ANO1/TMEM16A is located in the primary cilium, and blocking it pharmacologically or knocking it down with shRNA interferes with ciliogenesis. Before ciliogenesis, the channel is organized into a torus-shaped structure (the “nimbus”) enriched in proteins required for ciliogenesis. Many cells possess a single, nonmotile, primary cilium highly enriched in receptors and sensory transduction machinery that plays crucial roles in cellular morphogenesis. Although sensory transduction requires ion channels, relatively little is known about ion channels in the primary cilium (with the exception of TRPP2). Here we show that the Ca2+-activated Cl− channel anoctamin-1 (ANO1/TMEM16A) is located in the primary cilium and that blocking its channel function pharmacologically or knocking it down with short hairpin RNA interferes with ciliogenesis. Before ciliogenesis, the channel becomes organized into a torus-shaped structure (“the nimbus”) enriched in proteins required for ciliogenesis, including the small GTPases Cdc42 and Arl13b and the exocyst complex component Sec6. The nimbus excludes F-actin and coincides with a ring of acetylated microtubules. The nimbus appears to form before, or independent of, apical docking of the mother centriole. Our data support a model in which the nimbus provides a scaffold for staging of ciliary components for assembly very early in ciliogenesis and chloride transport by ANO1/TMEM16A is required for the genesis or maintenance of primary cilia.
Collapse
Affiliation(s)
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| |
Collapse
|