Calcium-Activated Chloride Channels in Newly Differentiating Mouse Lens Fiber Cells and Their Role in Volume Regulation

Tong, Jun-Jie; Acharya, Pooja; Ebihara, Lisa

doi:10.1167/iovs.19-26626

Cited by 5 publications

(8 citation statements)

References 39 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In conclusion, this study describes the effect of two potent modulators of the TRPV4 channels on the CaCCs, specifically on cloned TMEM16B and further experiments are required to understand the T out current enhancement in oocytes. Our findings suggest careful interpretations of pharmacological studies performed on tissues where TRPV4 and TMEM16B channels co-express [ 55 ] and helps to achieve precise conclusions in preclinical studies about TRPV4. Finally, our observations indicate that the GSKa/b structures may be used as templates to design new potent and selective drugs for TMEM16B.…”

Section: Discussionmentioning

confidence: 93%

“…Physical and functional coupling between CaCCs with TRPVs have been already demonstrated in heterologous expression and in tissues [ 43 , 44 , 52 ]. Studies to elucidate the possible pharmacological interaction of both channel families are essential to generate accurate conclusions, especially in tissues where both channels are expressed like in DRG, choroid plexus epithelial cells and retinal epithelium [ 26 , 44 , 45 , [53] , [54] , [55] ].…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Positive modulation of the TMEM16B mediated currents by TRPV4 antagonist

Hernández¹,

Alaniz-Palacios²,

Contreras-Vite³

et al. 2021

Biochemistry and Biophysics Reports

View full text Add to dashboard Cite

Calcium-activated chloride channels (CaCCs) play important roles in many physiological processes and their malfunction is implicated in diverse pathologies such as cancer, asthma, and hypertension. TMEM16A and TMEM16B proteins are the structural components of the CaCCs. Recent studies in cell cultures and animal models have demonstrated that pharmacological inhibition of CaCCs could be helpful in the treatment of some diseases, however, there are few specific modulators of these channels. CaCCs and Transient Receptor Potential Vanilloid-4 (TRPV4) channels are co-expressed in some tissues where they functionally interact. TRPV4 is activated by different stimuli and forms a calcium permeable channel that is activated by GSK1016790A and antagonized by GSK2193874. Here we report that GSK2193874 enhances the chloride currents mediated by TMEM16B expressed in HEK cells at nanomolar concentrations and that GSK1016790A enhances native CaCCs of Xenopus oocytes. Thus, these compounds may be used as a tool for the study of CaCCs, TRPV4 and their interactions.

show abstract

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Positive modulation of the TMEM16B mediated currents by TRPV4 antagonist

Hernández¹,

Alaniz-Palacios²,

Contreras-Vite³

et al. 2021

Biochemistry and Biophysics Reports

View full text Add to dashboard Cite

show abstract

“…In shorter fiber cells from the zone of chloride efflux, this chloride current was generally quiescent but could be activated by hypotonic challenge and/or addition of the KCC blocker, DIOA. More recently, we have shown that calcium-activated-chloride channels (CaCCs) composed of TMEM16A and TMEM16B were expressed in newly differentiating lens epithelial and fiber cells in wild-type and double knockout (KO) that lack both Cx50 and Cx46 using a combination of reverse transcript PCR (RT-PCR), immunohistochemistry and whole cell patch clamp techniques (Tong et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…One of the main advantages of using this preparation to perform electrophysiological experiments is that the isolation of fiber cells from lens of these KO mice can be performed using milder dissociation conditions than those used in past attempts to dissociate fiber cells, possibly due to alterations in cell adhesion properties (Wang et al, 2016;Hu et al, 2017). Another advantage is that the double KO fiber cells lack large, calcium-sensitive connexin hemichannel currents and can tolerate exposure to calcium-containing solutions without requiring the addition of non-specific cation channel blockers such as 1 mM Gadolinium to prevent fiber cell vesiculation and death (Ebihara et al, 2011;Tong et al, 2019). Our results demonstrate that CaCCs in dissociated lens can be rapidly and reversibly modulated by mechanical stress, consistent with their participation in regulation of volume in this organ.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Stress Modulates Calcium-Activated-Chloride Currents in Differentiating Lens Cells

2022

Self Cite

View full text Add to dashboard Cite

During accommodation, the lens changes focus by altering its shape following contraction and relaxation of the ciliary muscle. At the cellular level, these changes in shape may be accompanied by fluid flow in and out of individual lens cells. We tested the hypothesis that some of this flow might be directly modulated by pressure-activated channels. In particular, we used the whole cell patch clamp technique to test whether calcium-activated-chloride channels (CaCCs) expressed in differentiating lens cells are activated by mechanical stimulation. Our results show that mechanical stress, produced by focally perfusing the lens cell at a constant rate, caused a significant increase in a chloride current that could be fully reversed by stopping perfusion. The time course of activation and recovery from activation of the flow-induced current occurred rapidly over a time frame similar to that of accommodation. The flow-induced current could be inhibited by the TMEM16A specific CaCC blocker, Ani9, suggesting that the affected current was predominantly due to TMEM16A chloride channels. The mechanism of action of mechanical stress did not appear to involve calcium influx through other mechanosensitive ion channels since removal of calcium from the bath solution failed to block the flow-induced chloride current. In conclusion, our results suggest that CaCCs in the lens can be rapidly and reversibly modulated by mechanical stress, consistent with their participation in regulation of volume in this organ.

show abstract

“…They express large amounts of crystallins in the cytosol, they lose Na/K ATPase activity in the membranes, 8 and the abundance of potassium channels diminishes while expression of sodium and chloride leak channels increases. [9][10][11] These fibers are coupled by gap junctions made from Cx50 and Cx46. 12 Their coupling conductance is concentrated in the equatorial region.…”

mentioning

confidence: 99%

Signaling Between TRPV1/TRPV4 and Intracellular Hydrostatic Pressure in the Mouse Lens

Delamere

Shahidullah

Mathias

et al. 2020

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

Purpose The lens uses feedback to maintain zero pressure in its surface cells. Positive pressures are detected by transient receptor potential vanilloid (TRPV4), which initiates a cascade that reduces surface cell osmolarity. The first step is opening of gap junction hemichannels. One purpose of the current study was to identify the connexin(s) in the hemichannels. Negative pressures are detected by TRPV1, which initiates a cascade that increases surface osmolarity. The increase in osmolarity was initially reported to be through inhibition of Na/K ATPase activity, but a recent study reported it was through stimulation of Na/K/2Cl (NKCC) cotransport. A second purpose of this study was to reconcile these two reports. Methods Intracellular hydrostatic pressures were measured using a microelectrode/manometer system. Lenses from TRPV1 or Cx50 null mice were studied. Specific inhibitors of Cx50 gap junction channels, NKCC, and Akt were used. Results Either knockout of Cx50 or blockade of Cx50 channels completely eliminated the response to positive surface pressures. Knockout of Cx50 also caused a positive drift in surface pressure. The short-term (∼20-minute) response to negative surface pressures was eliminated by blockade of NKCC, but a long-term (∼4-hour) response restored pressure to zero. Both short- and long-term responses were eliminated by knockout of TRPV1 or inhibition of Akt. Conclusions Hemichannels made from Cx50 are required for the response to positive surface pressures. Negative surface pressures first activate NKCC, but a backup system is inhibition of Na/K ATPase activity. Both responses are initiated by TRPV1 and go through PI3K/Akt before branching.

show abstract

Calcium-Activated Chloride Channels in Newly Differentiating Mouse Lens Fiber Cells and Their Role in Volume Regulation

Cited by 5 publications

References 39 publications

Positive modulation of the TMEM16B mediated currents by TRPV4 antagonist

Positive modulation of the TMEM16B mediated currents by TRPV4 antagonist

Mechanical Stress Modulates Calcium-Activated-Chloride Currents in Differentiating Lens Cells

Signaling Between TRPV1/TRPV4 and Intracellular Hydrostatic Pressure in the Mouse Lens

Contact Info

Product

Resources

About