Structure-function analyses of human TRPV6 ancestral and derived haplotypes.

TRPV6 is a Ca selective channel that mediates calcium uptake in the gut and contributes to the development and progression of human cancers. TRPV6 is represented by the ancestral and derived haplotypes that differ by three non-synonymous polymorphisms, located in the N-terminal ankyrin repeat domain (C157R), S1-S2 extracellular loop (M378V), and C-terminus (M681T). The ancestral and derived haplotypes were proposed to serve as genomic factors causing a different outcome for cancer patients of African ancestry.

ATR-FTIR spectroscopic imaging with variable angles of incidence of crude oil deposits formed by flocculant flow.

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging is a method for spatially resolved analysis of materials that combines the capabilities of ATR-FTIR spectroscopy with the use of a focal plane array detector. This paper presents the methodological aspects of adapting the ATR accessory with variable single reflection angle to the FTIR spectroscopic imaging method. The use of a variable reflection angle allows the image to be studied at different sample depths.

TRPM2 channels are essential for regulation of cytokine production in lung interstitial macrophages.

Interstitial macrophages (IMs) are essential for organ homeostasis, inflammation, and autonomous immune response in lung tissues, which are achieved through polarization to a pro-inflammatory M1 and an M2 state for tissue repair. Their remote parenchymal localization and low counts, however, are limiting factors for their isolation and molecular characterization of their specific role during tissue inflammation. We isolated viable murine IMs in sufficient quantities by coculturing them with stromal cells and analyzed mRNA expression patterns of transient receptor potential (TRP) channels in naïve and M1 polarized IMs after application of lipopolysaccharide (LPS) and interferon γ.

The Effect of Calcium Ions on the Electrophysiological Properties of Single ANO6 Channels.

Proteins belonging to the anoctamin (ANO) family form calcium-activated chloride channels (CaCCs). The most unusual member of this family, ANO6 (TMEM16F), simultaneously exhibits the functions of calcium-dependent scramblase and the ion channel. ANO6 affects the plasma membrane dynamics and phosphatidylserine transport; it is also involved in programmed cell death.

Structural basis of selective TRPM7 inhibition by the anticancer agent CCT128930.

TRP channels are implicated in various diseases, but high structural similarity between them makes selective pharmacological modulation challenging. Here, we study the molecular mechanism underlying specific inhibition of the TRPM7 channel, which is essential for cancer cell proliferation, by the anticancer agent CCT128930 (CCT). Using cryo-EM, functional analysis, and MD simulations, we show that CCT binds to a vanilloid-like (VL) site, stabilizing TRPM7 in the closed non-conducting state.

Features of Wax Appearance Temperature Determination of Waxy Crude Oil Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy Under Ambient and High Pressure.

The wax appearance temperature (WAT), being one of the key characteristics of waxy crude oil and other waxy substances, is used for the necessary assessment of the phase stability of materials during various technological processes. However, the determination of this parameter as well as peculiarities of wax formation under high gas pressure suffers from the lack of suitable techniques for this task. To address this issue, an attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) method has been applied for the first time to measure the WAT of waxy crude oil under high gas pressure.

Calcium chelation independent effects of BAPTA on endogenous ANO6 channels in HEK293T cells.

Selective calcium chelator 1,2-Bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) is a common tool to investigate calcium signaling. However, BAPTA expresses various effects on intracellular calcium signaling, which are not related to its ability to bind Ca. In patch clamp experiments, we investigated calcium chelation independent effects of BAPTA on endogenous calcium-activated chloride channels ANO6 (TMEM16F) in HEK293T cells.

Reductive Transformation of O-, N-, S-Containing Aromatic Compounds under Hydrogen Transfer Conditions: Effect of the Process on the Ni-Based Catalyst.

The influence of the reaction medium on the surface structure and properties of a Ni-based catalyst used for the reductive transformations of O-, N-, and S-containing aromatic substrates under hydrogen transfer conditions has been studied. The catalysts were characterized by XRD, XPS, and IR spectroscopy and TEM methods before and after the reductive reaction. It has been shown that the conversion of 1-benzothiophene causes irreversible poisoning of the catalyst surface with the formation of the NiS phase, whereas the conversion of naphthalene, 1-benzofuran, and indole does not cause any phase change of the catalyst at 250 °C.

Reorganization and Suppression of Store-Operated Calcium Entry in Podocytes of Type 2 Diabetic Rats.

Type 2 diabetes mellitus (DM2) is a widespread metabolic disorder that results in podocyte damage and diabetic nephropathy. Previous studies demonstrated that TRPC6 channels play a pivotal role in podocyte function and their dysregulation is associated with development of different kidney diseases including nephropathy. Here, using single channel patch clamp technique, we demonstrated that non-selective cationic TRPC6 channels are sensitive to the Ca store depletion in human podocyte cell line Ab8/13 and in freshly isolated rat glomerular podocytes.

The STIM1/2-Regulated Calcium Homeostasis Is Impaired in Hippocampal Neurons of the 5xFAD Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common cause of age-related dementia. Neuronal calcium homeostasis impairment may contribute to AD. Here we demonstrated that voltage-gated calcium (VGC) entry and store-operated calcium (SOC) entry regulated by calcium sensors of intracellular calcium stores STIM proteins are affected in hippocampal neurons of the 5xFAD transgenic mouse model.

Crosstalk between epithelial sodium channels (ENaC) and basolateral potassium channels (K 4.1/K 5.1) in the cortical collecting duct.

Background And Purpose: Inwardly rectifying K (K ) channels located on the basolateral membrane of epithelial cells of the distal nephron play a crucial role in K handling and BP control, making these channels an attractive target for the treatment of hypertension. The purpose of the present study was to determine how the inhibition of basolateral K 4.1/K 5.

Role of STIM2 and Orai proteins in regulating TRPC1 channel activity upon calcium store depletion.

Store-operated calcium channels are the major player in calcium signaling in non-excitable cells. Store-operated calcium entry is associated with the Orai, stromal interaction molecule (STIM), and transient receptor potential canonical (TRPC) protein families. Researchers have provided conflicting data about TRPC1 channel regulation by Orai and STIM.

A Novel Modulator of STIM2-Dependent Store-Operated Ca2+ Channel Activity.

Store-operated Ca entry is one of the main pathways of calcium influx into non-excitable cells, which entails the initiation of many intracellular processes. The endoplasmic reticulum Ca sensors STIM1 and STIM2 are the key components of store-operated Ca entry in mammalian cells. Under physiological conditions, STIM proteins are responsible for store-operated Ca entry activation.

Electrophysiological Properties of Endogenous Single Ca Activated Cl Channels Induced by Local Ca Entry in HEK293.

Microdomains formed by proteins of endoplasmic reticulum and plasma membrane play a key role in store-operated Ca entry (SOCE). Ca release through inositol 1,4,5-trisphosphate receptor (IPR) and subsequent Ca store depletion activate STIM (stromal interaction molecules) proteins, sensors of intraluminal Ca, which, in turn, open the Orai channels in plasma membrane. Downstream to this process could be activated TRPC (transient receptor potential-canonical) calcium permeable channels.

Cytoskeleton Rearrangements Modulate TRPC6 Channel Activity in Podocytes.

The actin cytoskeleton of podocytes plays a central role in the functioning of the filtration barrier in the kidney. Calcium entry into podocytes via TRPC6 (Transient Receptor Potential Canonical 6) channels leads to actin cytoskeleton rearrangement, thereby affecting the filtration barrier. We hypothesized that there is feedback from the cytoskeleton that modulates the activity of TRPC6 channels.

Store-Operated Calcium Entry in Mouse Cardiomyocytes.

The fluorescent dye fura-2 AM was employed to record activation of Ca entry in response to a decrease in Ca concentration in the endoplasmic reticulum. Using whole-cell voltage clamp technique, we revealed Ca currents with an amplitude of 0.46±0.

Inactivation of p66Shc Decreases Afferent Arteriolar K Channel Activity and Decreases Renal Damage in Diabetic Dahl SS Rats.

Increased expression of adaptor protein p66Shc has been associated with progression of diabetic nephropathy. Afferent arteriolar dilation and glomerular hyperfiltration in diabetes are due to increased K channel availability and activity. Hyperglycemia was induced in Dahl salt-sensitive (SS) rats in a model of diabetes induced by streptozotocin (STZ).

Patient-Specific iPSC-Based Models of Huntington's Disease as a Tool to Study Store-Operated Calcium Entry Drug Targeting.

Neurodegenerative pathologies are among the most serious and socially significant problems of modern medicine, along with cardiovascular and oncological diseases. Several attempts have been made to prevent neuronal death using novel drugs targeted to the cell calcium signaling machinery, but the lack of adequate models for screening markedly impairs the development of relevant drugs. A potential breakthrough in this field is offered by the models of hereditary neurodegenerative pathologies based on endogenous expression of mutant proteins in neurons differentiated from patient-specific induced pluripotent stem cells (iPSCs).

Homer 1a Induces Calcium Channel Activation, but Does Not Change Their Properties in A431 Cells.

Store-operated channels activated in response to intracellular calcium store depletion represent the main pathway of calcium entry from the extracellular space in nonelectroexcitable cells. Adapter proteins organize the components of this system into integral complex. We studied the influence of adapter proteins of the Homer family on endogenous store-operated calcium Imin channels in A431 cells.

Electrophysiological Features of Single Store-Operated Calcium Channels in HEK S4 Cell Line with Stable STIM1 Protein Knockdown.

An important role in intracellular calcium signaling is played by store-operated channels activated by STIM proteins, calcium sensors of the endoplasmic reticulum. In stable STIM1 knockdown HEK S4 cells, single channels activated by depletion of intracellular calcium stores were detected by cell-attached patch-clamp technique and their electrophysiological parameters were described. Comparison of the properties of single channels in HEK293 and HEK S4 cells revealed no significant differences in their current-voltage curves, while regulation of store-operated calcium channels in these cell lines depended on the level of STIM1 expression.

Huntington's Disease: Calcium Dyshomeostasis and Pathology Models.

Huntington's disease (HD) is a severe inherited neurodegenerative disorder characterized by motor dysfunction, cognitive decline, and mental impairment. At the molecular level, HD is caused by a mutation in the first exon of the gene encoding the huntingtin protein. The mutation results in an expanded polyglutamine tract at the N-terminus of the huntingtin protein, causing the neurodegenerative pathology.

STIM1 and STIM2 proteins differently regulate endogenous store-operated channels in HEK293 cells.

The endoplasmic reticulum calcium sensors stromal interaction molecules 1 and 2 (STIM1 and STIM2) are key modulators of store-operated calcium entry. Both these sensors play a major role in physiological functions in normal tissue and in pathology, but available data on native STIM2-regulated plasma membrane channels are scarce. Only a few studies have recorded STIM2-induced CRAC (calcium release-activated calcium) currents.

TRPC1 protein forms only one type of native store-operated channels in HEK293 cells.

TRPC1 is a major component of store-operated calcium entry in many cell types. In our previous studies, three types of endogenous store-operated calcium channels have been described in HEK293 cells, but it remained unknown which of these channels are composed of TRPC1 proteins. Here, this issue has been addressed by performing single-channel analysis in HEK293 cells transfected with anti-TRPC1 siRNA (siTPRC1) or a TPRC1-encoding plasmid.

Homer regulation of native plasma membrane calcium channels in A431 cells.

Homers are adapter proteins that play a significant role in the organization of calcium signaling protein complexes. Previous functional studies linked Homer proteins to calcium influx in nonexcitable cells. These studies utilized calcium imaging or whole-cell current recordings.