scholarly journals CNNM proteins selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells

PLoS Biology ◽  
2021 ◽  
Vol 19 (12) ◽  
pp. e3001496
Author(s):  
Zhiyong Bai ◽  
Jianlin Feng ◽  
Gijs A. C. Franken ◽  
Namariq Al’Saadi ◽  
Na Cai ◽  
...  
Keyword(s):  
Divalent Cation ◽  
Divalent Cations ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Cellular Life ◽  
Binding Partners ◽  
Cation Uptake ◽  
Electrophysiological Recordings ◽  
293 Cells ◽  
Inactivating Mutation

Magnesium is essential for cellular life, but how it is homeostatically controlled still remains poorly understood. Here, we report that members of CNNM family, which have been controversially implicated in both cellular Mg2+ influx and efflux, selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells. Coexpression of CNNMs with the channel markedly increased uptake of divalent cations, which is prevented by an inactivating mutation to the channel’s pore. Knockout (KO) of Trpm7 in cells or application of the TRPM7 channel inhibitor NS8593 also interfered with CNNM-stimulated divalent cation uptake. Conversely, KO of CNNM3 and CNNM4 in HEK-293 cells significantly reduced TRPM7-mediated divalent cation entry, without affecting TRPM7 protein expression or its cell surface levels. Furthermore, we found that cellular overexpression of phosphatases of regenerating liver (PRLs), known CNNMs binding partners, stimulated TRPM7-dependent divalent cation entry and that CNNMs were required for this activity. Whole-cell electrophysiological recordings demonstrated that deletion of CNNM3 and CNNM4 from HEK-293 cells interfered with heterologously expressed and native TRPM7 channel function. We conclude that CNNMs employ the TRPM7 channel to mediate divalent cation influx and that CNNMs also possess separate TRPM7-independent Mg2+ efflux activities that contribute to CNNMs’ control of cellular Mg2+ homeostasis.

Extracellular Ca2+-sensing receptor is a promiscuous divalent cation sensor that responds to lead

2000 ◽  
Vol 279 (6) ◽  
pp. F1083-F1091 ◽  
Author(s):  
Mary E. Handlogten ◽  
Naoki Shiraishi ◽  
Hisataka Awata ◽  
Chunfa Huang ◽  
R. Tyler Miller
Keyword(s):  
Divalent Cations ◽  
Mitogen Activated Protein Kinase ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Mitogen Activated Protein ◽  
Measured Activation ◽  
Hill Coefficients ◽  
The Hill ◽  
Kinetics Of

The extracellular Ca2+-sensing receptor (CaR) responds to polycations, including Ca2+ and neomycin. This receptor is a physiological regulator of systemic Ca2+ metabolism and may also mediate the toxic effects of hypercalcemia. A number of divalent cations, including Pb2+, Co2+, Cd2+, and Fe2+, are toxic to the kidney, brain, and other tissues where the CaR is expressed. To determine which divalent cations can activate the CaR, we expressed the human CaR in HEK-293 cells and measured activation of phospholipase A2(PLA2) and the mitogen-activated protein kinase p42ERK in response to potential agonists for the receptor. HEK-293 cells expressing the nonfunctional mutant CaR R796W served as controls. Extracellular Ca2+, Ba2+, Cd2+, Co2+, Fe2+, Gd3+, Ni2+, Pb2+, and neomycin activated the CaR, but Hg2+and Fe3+ did not. We analyzed the kinetics of activation of p42ERK and PLA2 by the CaR in response to Ca2+, Co2+, and Pb2+. The EC50 values ranged from ∼0.1 mM for Pb2+ to ∼4.0 mM for Ca2+. The Hill coefficients were >3, indicating multiple cooperative ligand binding sites or subunits. Submaximal concentrations of Ca2+ and Pb2+ were additive for activation of the CaR. The EC50 for Ca2+ or Pb2+ was reduced four- to fivefold by the presence of the other ion. These divalent cations also activated PLA2 via the CaR in Madin-Darby canine kidney cells that stably express the CaR. We conclude that many divalent cations activate the CaR and that their effects are additive. The facts that the CaR is a promiscuous polycation sensor and that the effects of these ions are additive to activate it suggest that the CaR may contribute to the toxicity of some heavy metals such as Pb2+, Cd2+, Co2+, and Fe2+ for the kidney and other tissues where it is expressed.

scholarly journals Characteristics and requirements of basal autophagy in HEK 293 cells

Autophagy ◽  
2013 ◽  
Vol 9 (9) ◽  
pp. 1407-1417 ◽  
Author(s):  
Patience Musiwaro ◽  
Matthew Smith ◽  
Maria Manifava ◽  
Simon A. Walker ◽  
Nicholas T. Ktistakis
Keyword(s):  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells

Halothane Inhibition of Recombinant Cardiac L-type Ca2+ Channels Expressed in HEK-293 Cells

2005 ◽  
Vol 103 (6) ◽  
pp. 1156-1166 ◽  
Author(s):  
Kevin J. Gingrich ◽  
Son Tran ◽  
Igor M. Nikonorov ◽  
Thomas J. Blanck
Keyword(s):  
Charge Transfer ◽  
Calcium Channels ◽  
Dependent Manner ◽  
Current Time ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Dependent Inactivation ◽  
Voltage Dependent

Background Volatile anesthetics depress cardiac contractility, which involves inhibition of cardiac L-type calcium channels. To explore the role of voltage-dependent inactivation, the authors analyzed halothane effects on recombinant cardiac L-type calcium channels (alpha1Cbeta2a and alpha1Cbeta2aalpha2/delta1), which differ by the alpha2/delta1 subunit and consequently voltage-dependent inactivation. Methods HEK-293 cells were transiently cotransfected with complementary DNAs encoding alpha1C tagged with green fluorescent protein and beta2a, with and without alpha2/delta1. Halothane effects on macroscopic barium currents were recorded using patch clamp methodology from cells expressing alpha1Cbeta2a and alpha1Cbeta2aalpha2/delta1 as identified by fluorescence microscopy. Results Halothane inhibited peak current (I(peak)) and enhanced apparent inactivation (reported by end pulse current amplitude of 300-ms depolarizations [I300]) in a concentration-dependent manner in both channel types. alpha2/delta1 coexpression shifted relations leftward as reported by the 50% inhibitory concentration of I(peak) and I300/I(peak)for alpha1Cbeta2a (1.8 and 14.5 mm, respectively) and alpha1Cbeta2aalpha2/delta1 (0.74 and 1.36 mm, respectively). Halothane reduced transmembrane charge transfer primarily through I(peak) depression and not by enhancement of macroscopic inactivation for both channels. Conclusions The results indicate that phenotypic features arising from alpha2/delta1 coexpression play a key role in halothane inhibition of cardiac L-type calcium channels. These features included marked effects on I(peak) inhibition, which is the principal determinant of charge transfer reductions. I(peak) depression arises primarily from transitions to nonactivatable states at resting membrane potentials. The findings point to the importance of halothane interactions with states present at resting membrane potential and discount the role of inactivation apparent in current time courses in determining transmembrane charge transfer.

Micropatterned surfaces of PDMS as growth templates for HEK 293 cells

2007 ◽  
Vol 9 (4) ◽  
pp. 475-485 ◽  
Author(s):  
R. M. Johann ◽  
Ch. Baiotto ◽  
Ph. Renaud
Keyword(s):  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells

Calcium Induces Expression of Cytoplasmic Gelsolin in SH-SY5Y and HEK-293 Cells

2010 ◽  
Vol 35 (7) ◽  
pp. 1075-1082 ◽  
Author(s):  
Lina Ji ◽  
Abha Chauhan ◽  
Ved Chauhan
Keyword(s):  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Cytoplasmic Gelsolin

Characteristics of rat downregulated in adenoma (rDRA) expressed in HEK 293 cells

2007 ◽  
Vol 454 (3) ◽  
pp. 441-450 ◽  
Author(s):  
Christian Barmeyer ◽  
Jeff Huaqing Ye ◽  
Shafik Sidani ◽  
John Geibel ◽  
Henry J. Binder ◽  
...  
Keyword(s):  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells

Abstract 5316: hERG 1b as a Potential Target for Inherited and Acquired Long QT Syndrome

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Gail A Robertson ◽  
Harinath Sale ◽  
David Tester ◽  
Thomas J O’Hara ◽  
Pallavi Phartiyal ◽  
...  
Keyword(s):  
Action Potential ◽  
Long Qt Syndrome ◽  
Time Course ◽  
Drug Sensitivity ◽  
Long Qt ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Acquired Long Qt Syndrome ◽  
293 Cells ◽  
Qt Syndrome

Cardiac I Kr is a critical repolarizing current in the heart and a target for inherited and acquired long QT syndrome. Biochemical studies show that native I Kr channels are heteromers composed of both hERG 1a and 1b subunits, yet our current understanding of I Kr functional properties derives primarily from studies of homo-oligomers of the original hERG 1a isolate. The hERG 1a and 1b subunits are identical except at the amino (NH2) terminus, which in hERG 1b is much shorter and has a unique primary sequence. We compared the biophysical properties of currents produced by hERG 1a and 1a/1b channels expressed in HEK-293 cells at near-physiological temperatures. We found that heteromeric hERG 1a/1b currents are much larger than hERG 1a currents and conduct 80% more charge during an action potential. This surprising difference corresponds to a two-fold increase in the apparent rates of activation and recovery from inactivation, which reduces rectification and facilitates current rebound during repolarization. Kinetic modeling shows these gating differences account quantitatively for the differences in current amplitude between the two channel types. Depending on the action potential model used, loss of 1b predicts an increase in action potential duration of 27 ms (7%) or 41 ms (17%), respectively. Drug sensitivity was also different. Compared to homomeric 1a channels, heteromeric 1a/1b channels were inhibited by E-4031 with a slower time course and a corresponding four-fold positive shift in the IC 50 . Differences in current kinetics and drug sensitivity were modeled by “NH2 mode” gating with conformational states bound by the amino terminus in hERG 1a homomers but not 1a/1b heteromers. The importance of hERG 1b in vivo is supported by the identification of a 1b-specific A8V missense mutation in 1/269 unrelated genotype-negative LQTS patients and absent in 400 control alleles. Mutant 1bA8V expressed alone or with hERG 1a in HEK-293 cells nearly eliminated 1b protein. Thus, mutations specifically disrupting hERG 1b function are expected to reduce cardiac I Kr , prolong QT interval and enhance drug sensitivity, thus representing a potential mechanism underlying inherited or acquired LQTS.

COOH-terminal association of human smooth muscle calcium channel Cav1.2b with Src kinase protein binding domains: effect of nitrotyrosylation

2007 ◽  
Vol 293 (6) ◽  
pp. C1983-C1990 ◽  
Author(s):  
Minho Kang ◽  
Gracious R. Ross ◽  
Hamid I. Akbarali
Keyword(s):  
Smooth Muscle ◽  
Calcium Channel ◽  
Tyrosine Phosphorylation ◽  
Src Kinase ◽  
Sh2 Domain ◽  
Calcium Currents ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Binding Domains ◽  
293 Cells

The carboxyl terminus of the calcium channel plays an important role in the regulation of calcium entry, signal transduction, and gene expression. Potential protein-protein interaction sites within the COOH terminus of the L-type calcium channel include those for the SH3 and SH2 binding domains of c-Src kinase that regulates calcium currents in smooth muscle. In this study, we examined the binding sites involved in Src kinase-mediated phosphorylation of the human voltage-gated calcium channel (Cav) 1.2b (hCav1.2b) and the effect of nitrotyrosylation. Cotransfection of human embryonic kidney (HEK)-293 cells with hCav1.2b and c-Src resulted in tyrosine phosphorylation of the calcium channel, which was prevented by nitration of tyrosine residues by peroxynitrite. Whole cell calcium currents were reduced by 58 + 5% by the Src kinase inhibitor PP2 and 64 + 6% by peroxynitrite. Nitrotyrosylation prevented Src-mediated regulation of the currents. Glutathione S-transferase fusion protein of the distal COOH terminus of hCav1.2b (1809-2138) bound to SH2 domain of Src following tyrosine phosphorylation, while binding to SH3 required the presence of the proline-rich motif. Site-directed mutation of Y2134 prevented SH2 binding and resulted in reduced phosphorylation of hCav1.2b. Within the distal COOH terminus, single, double, or triple mutations of Y1837, Y1861, and Y2134 were constructed and expressed in HEK-293 cells. The inhibitory effects of PP2 and peroxynitrite on calcium currents were significantly reduced in the double mutant Y1837-2134F. These data demonstrate that the COOH terminus of hCav1.2b contains sites for the SH2 and SH3 binding of Src kinase. Nitrotyrosylation of these sites prevents Src kinase regulation and may be importantly involved in calcium influx regulation during inflammation.

scholarly journals Multidrug resistance-associated protein 9 (ABCC12) is present in mouse and boar sperm

2007 ◽  
Vol 406 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Nobuhito Ono ◽  
Ingrid Van der Heijden ◽  
George L. Scheffer ◽  
Koen Van de Wetering ◽  
Elizabeth Van Deemter ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Kidney Cells ◽  
Cell Fractionation ◽  
Hek 293 ◽  
Human Embryonic Kidney Cells ◽  
Hek 293 Cells ◽  
Drug Conjugates ◽  
293 Cells ◽  
Boar Sperm ◽  
Alternatively Spliced

The human and murine genes for MRP9 (multidrug resistance-associated protein 9; ABCC12) yield many alternatively spliced RNAs. Using a panel of monoclonal antibodies, we detected full-length Mrp9 only in testicular germ cells and mouse sperm; we obtained no evidence for the existence of the truncated 100 kDa MRP9 protein reported previously. In contrast with other MRPs, neither murine Mrp9 nor the human MRP9 produced in MRP9-transfected HEK-293 cells (human embryonic kidney cells) appears to contain N-linked carbohydrates. In mouse and boar sperm, Mrp9 localizes to the midpiece, a structure containing all sperm mitochondria. However, immunolocalization microscopy and cell fractionation studies with transfected HEK-293 cells and mouse testis show that MRP9/Mrp9 does not localize to mitochondria. In HEK-293 cells, it is predominantly localized in the endoplasmic reticulum. We have been unable to demonstrate transport by MRP9 of substrates transported by other MRPs, such as drug conjugates and other organic anions.

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