Communication between the calcium and cAMP pathways regulate the expression of the TSH receptor: TRPC2 in the center of action

Iodine status and associated dietary factors among preschool children in Shanghai

Children aged 3-6 years undergo a critical stage of growth and development and are irreversibly affected by their iodine status. In order to reveal iodine status in preschool children, we detected iodine concentrations in urine samples from 1382 children aged 3-6 years based on a cross-sectional study. The median urinary iodine concentration (UIC) of children was 193.36 μg/L and was 336.96 μg/g·Cr corrected for creatinine. The study developed a link between dietary habits and iodine status, revealing that regular calcium supplement (OR: 1.79, (95% CI: 1.03, 3.12)) increased deficiency risk, while moderate seafood consumption (OR: 0.60, (95% CI: 0.38, 0.95)) decreased it. Additionally, modest intake of shellfish (OR: 0.58, (95% CI: 0.33, 1.00)), vegetables (OR: 0.61, (95% CI: 0.38, 0.97)), and eggs (OR: 0.53, (95% CI: 0.30, 0.95)) was found to protect against excess iodine. The findings underline the importance of balanced diets and various nutrients' roles in preschoolers' iodine status.

Stromal interaction molecule 1 (STIM1) knock down attenuates invasion and proliferation and enhances the expression of thyroid-specific proteins in human follicular thyroid cancer cells

Stromal interaction molecule 1 (STIM1) and the ORAI1 calcium channel mediate store-operated calcium entry (SOCE) and regulate a multitude of cellular functions. The identity and function of these proteins in thyroid cancer remain elusive. We show that STIM1 and ORAI1 expression is elevated in thyroid cancer cell lines, compared to primary thyroid cells. Knock-down of STIM1 or ORAI1 attenuated SOCE, reduced invasion, and the expression of promigratory sphingosine 1-phosphate and vascular endothelial growth factor-2 receptors in thyroid cancer ML-1 cells. Cell proliferation was attenuated in these knock-down cells due to increased G1 phase of the cell cycle and enhanced expression of cyclin-dependent kinase inhibitory proteins p21 and p27. STIM1 protein was upregulated in thyroid cancer tissue, compared to normal tissue. Downregulation of STIM1 restored expression of thyroid stimulating hormone receptor, thyroid specific proteins and increased iodine uptake. STIM1 knockdown ML-1 cells were more susceptible to chemotherapeutic drugs, and significantly reduced tumor growth in Zebrafish. Furthermore, STIM1-siRNA-loaded mesoporous polydopamine nanoparticles attenuated invasion and proliferation of ML-1 cells. Taken together, our data suggest that STIM1 is a potential diagnostic and therapeutic target for treatment of thyroid cancer.

Calcium Signaling in the Thyroid: Friend and Foe

Simple Summary

All cells in our body are activated by several different signals. The calcium ion is one of the most versatile signaling molecules, and regulates a multitude of different events in the cells. These range from activation of muscle contraction, to the regulation of cell movement, just to name a few. In normal thyroid cells, calcium signaling is of importance for the normal physiology of the cells. In thyroid pathologies, e.g., thyroid cancer, calcium is important for the regulation of proliferation and invasion, and may also activate gene transcription programs important for cancer cell survival. In this Commentary, we summarize what is known regarding calcium in the normal thyroid, and highlight the importance of calcium signaling in thyroid pathologies.

Abstract

Calcium signaling participates in a vast number of cellular processes, ranging from the regulation of muscle contraction, cell proliferation, and mitochondrial function, to the regulation of the membrane potential in cells. The actions of calcium signaling are, thus, of great physiological significance for the normal functioning of our cells. However, many of the processes that are regulated by calcium, including cell movement and proliferation, are important in the progression of cancer. In the normal thyroid, calcium signaling plays an important role, and evidence is also being gathered showing that calcium signaling participates in the progression of thyroid cancer. This review will summarize what we know in regard to calcium signaling in the normal thyroid as, well as in thyroid cancer.

Size-Dependent Effects of Suspended Graphene Oxide Nanoparticles on the Cellular Fate of Mouse Neural Stem Cells

PURPOSE

In this study, we aim to explore the effects of graphene oxide (GO), a derivative of graphene, nanoparticles of four different sizes on the cellular fate of mouse neural stem cells (mNSCs).

METHODS

GO NPs were characterized with transmission electron microscopy (TEM), scanning electron micrography (SEM), atomic force microscopy (AFM) and Raman Spectra analysis. The cytotoxic effects of the GO NPs of different sizes on the mNSCs were determined using CCK-8 assay, Annexin V-APC/ 7-AAD staining and EdU staining assays. We investigated the biological and the mechanisms of GO NPs on cells using immunofluorescence analysis and quantitative real-time PCR (qPCR).

RESULTS

The average hydrodynamic sizes of the GO NPs were 417 nm, 663 nm, 1047 nm, and 4651 nm, with a thickness of approximately 22.5 nm, 17.7 nm, 22.4 nm, and 13.4 nm, respectively. GO NPs of all sizes showed low cytotoxicity at a concentration of 20 μg/mL on the mNSCs. Immunostaining demonstrated that treatment with GO NPs, especially the 663 nm ones, enhanced the self-renewal ability of mNSCs in the absence of EGF and bFGF. Under differentiation medium conditions that are free of mitogenic factors, all the GO NPs, particularly the 4651 nm ones, increased the expression level of Tuj1 and GFAP. With regards to the migration ability, we found that 417 nm GO-NP-treated mNSCs migrated over a longer distance than the control group obviously. In addition, higher expression of Rap1, Vinculin and Paxillin was observed in the GO NP-treated groups compared to the control group. mRNA-Sequence analysis and Western blotting results suggested that the 4651 nm GO NPs triggered positive neuronal differentiation through phosphorylation of ERK1/2 by the downregulating of TRPC2.

CONCLUSION

GO NPs play an important role in the applications of inducing self-renewal and differentiation of mNSC, and are promising in the future for further studies.

3-Iodothyronamine, a Novel Endogenous Modulator of Transient Receptor Potential Melastatin 8?

The decarboxylated and deiodinated thyroid hormone (TH) derivative, 3-iodothyronamine (3-T₁AM), is suggested to be involved in energy metabolism and thermoregulation. G protein-coupled receptors (GPCRs) are known as the main targets for 3-T₁AM; however, transient receptor potential channels (TRPs) were also recently identified as new targets of 3-T₁AM. This article reviews the current knowledge of a putative novel role of 3-T₁AM in the modulation of TRPs. Specifically, the TRP melastatin 8 (TRPM8) was identified as a target of 3-T₁AM in different cell types including neoplastic cells, whereby 3-T₁AM significantly increased cytosolic Ca²⁺ through TRPM8 activation. Similarly, the β-adrenergic receptor is involved in 3-T₁AM-induced Ca²⁺ influx. Therefore, it has been suggested that 3-T₁AM-induced Ca²⁺ mobilization might be due to β-adrenergic receptor/TRPM8 channel interaction, which adds to the complexity of GPCR regulation by TRPs. It has been revealed that TRPM8 activation leads to a decline in TRPV1 activity, which may be of therapeutic benefit in clinical circumstances such as treatment of TRPV1-mediated inflammatory hyperalgesia, colitis, and dry eye syndrome. This review also summarizes the inverse association between changes in TRPM8 and TRPV1 activity after 3-T₁AM stimulation. This finding prompted further detailed investigations of the interplay between 3-T₁AM and the GPCR/TRPM8 axis and indicated the probability of additional GPCR/TRP constellations that are modulated by this TH derivative.

Transient Receptor Potential Canonical 1 (TRPC1) Channels as Regulators of Sphingolipid and VEGF Receptor Expression: IMPLICATIONS FOR THYROID CANCER CELL MIGRATION AND PROLIFERATION

The identity of calcium channels in the thyroid is unclear. In human follicular thyroid ML-1 cancer cells, sphingolipid sphingosine 1-phosphate (S1P), through S1P receptors 1 and 3 (S1P1/S1P3), and VEGF receptor 2 (VEGFR2) stimulates migration. We show that human thyroid cells express several forms of transient receptor potential canonical (TRPC) channels, including TRPC1. In TRPC1 knockdown (TRPC1-KD) ML-1 cells, the basal and S1P-evoked invasion and migration was attenuated. Furthermore, the expression of S1P3 and VEGFR2 was significantly down-regulated. Transfecting wild-type ML-1 cells with a nonconducting TRPC1 mutant decreased S1P3 and VEGFR2 expression. In TRPC1-KD cells, receptor-operated calcium entry was decreased. To investigate whether the decreased receptor expression was due to attenuated calcium entry, cells were incubated with the calcium chelator BAPTA-AM (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid). In these cells, and in cells where calmodulin and calmodulin-dependent kinase were blocked pharmacologically, S1P3 and VEGFR2 expression was decreased. In TRPC1-KD cells, both hypoxia-inducible factor 1α expression and the secretion and activity of MMP2 and MMP9 were attenuated, and proliferation was decreased in TRPC1-KD cells. This was due to a prolonged G1 phase of the cell cycle, a significant increase in the expression of the cyclin-dependent kinase inhibitors p21 and p27, and a decrease in the expression of cyclin D2, cyclin D3, and CDK6. Transfecting TRPC1 to TRPC1-KD cells rescued receptor expression, migration, and proliferation. Thus, the expression of S1P3 and VEGFR2 is mediated by a calcium-dependent mechanism. TRPC1 has a crucial role in this process. This regulation is important for the invasion, migration, and proliferation of thyroid cancer cells.

TRPC1-mediated Ca²⁺ entry is essential for the regulation of hypoxia and nutrient depletion-dependent autophagy

Autophagy is a cellular catabolic process needed for the degradation and recycling of protein aggregates and damaged organelles. Although Ca²⁺ is suggested to have an important role in cell survival, the ion channel(s) involved in autophagy have not been identified. Here we demonstrate that increase in intracellular Ca²⁺ via transient receptor potential canonical channel-1 (TRPC1) regulates autophagy, thereby preventing cell death in two morphologically distinct cells lines. The addition of DMOG or DFO, a cell permeable hypoxia-mimetic agents, or serum starvation, induces autophagy in both epithelial and neuronal cells. The induction of autophagy increases Ca²⁺ entry via the TRPC1 channel, which was inhibited by the addition of 2APB and SKF96365. Importantly, TRPC1-mediated Ca²⁺ entry resulted in increased expression of autophagic markers that prevented cell death. Furthermore, hypoxia-mediated autophagy also increased TRPC1, but not STIM1 or Orai1, expression. Silencing of TRPC1 or inhibition of autophagy by 3-methyladenine, but not TRPC3, attenuated hypoxia-induced increase in intracellular Ca²⁺ influx, decreased autophagy, and increased cell death. Furthermore, the primary salivary gland cells isolated from mice exposed to hypoxic conditions also showed increased expression of TRPC1 as well as increase in Ca²⁺ entry along with increased expression of autophagic markers. Altogether, we provide evidence for the involvement of Ca²⁺ influx via TRPC1 in regulating autophagy to protect against cell death.

Canonical transient receptor potential channel 2 (TRPC2): old name-new games. Importance in regulating of rat thyroid cell physiology

In addition to the TSH-cyclic AMP signalling pathway, calcium signalling is of crucial importance in thyroid cells. Although the importance of calcium signalling has been thoroughly investigated for several decades, the nature of the calcium channels involved in signalling is unknown. In a recent series of investigations using the well-studied rat thyroid FRTL-5 cell line, we showed that these cells exclusively express the transient receptor potential canonical 2 (TRPC2) channel. Our results suggested that the TRPC2 channel is of significant importance in regulating thyroid cell function. These investigations were the first to show that thyroid cells express a member of the TRPC family of ion channels. In this review, we will describe the importance of the TRPC2 channel in regulating TSH receptor expression, thyroglobulin maturation, intracellular calcium and iodide homeostasis and that the channel also regulates thyroid cell proliferation.

Hydrogen sulfide maintains mesenchymal stem cell function and bone homeostasis via regulation of Ca(2+) channel sulfhydration

Gaseous signaling molecules such as hydrogen sulfide (H2S) are produced endogenously and mediate effects through diverse mechanisms. H2S is one such gasotransmitters that regulates multiple signaling pathways in mammalian cells, and abnormal H2S metabolism has been linked to defects in bone homeostasis. Here, we demonstrate that bone marrow mesenchymal stem cells (BMMSCs) produce H2S in order to regulate their self-renewal and osteogenic differentiation, and H2S deficiency results in defects in BMMSC differentiation. H2S deficiency causes aberrant intracellular Ca(2+) influx because of reduced sulfhydration of cysteine residues on multiple Ca(2+) TRP channels. This decreased Ca(2+) flux downregulates PKC/Erk-mediated Wnt/β-catenin signaling which controls osteogenic differentiation of BMMSCs. Consistently, H2S-deficient mice display an osteoporotic phenotype that can be rescued by small molecules that release H2S. These results demonstrate that H2S regulates BMMSCs and that restoring H2S levels via nontoxic donors may provide treatments for diseases such as osteoporosis that can arise from H2S deficiencies.

TRPs in olfaction

The mammalian olfactory system has become an excellent model system to understand the function of transient receptor potential (TRP) channels within their native cellular and circuit environment. The discovery that the canonical TRP channel TRPC2 is highly expressed in sensory neurons of the vomeronasal organ (VNO) has led to major advances in our understanding of the cellular and molecular processes underlying signal transduction of pheromones and other molecular cues that play an essential role in the control of instinctive decisions and innate social behaviors. TRPC2 knockout mice provide a striking example that the loss of function of a single gene can cause severe alterations in a variety of social interactions including the display of aggression, social dominance, and sexual behaviors. There is mounting evidence that TRPC2 is not the only TRP channel expressed in cells of the olfactory system but that other TRP channel subtypes such as TRPC1, TRPC4, TRPC6, TRPM4, and TRPM5 could also play important functional roles in mammalian olfaction. Here, I review such findings and discuss future areas for investigation.

Local thyroid renin-angiotensin system in experimental breast cancer

An association between breast cancer and thyroid dysfunction exists although the underlying mechanisms remain to be elucidated. Numerous studies have characterized the role of thyroid hormones in controlling the synthesis and secretion of renin-angiotensin system (RAS) components, but little information is available on the putative role of the local RAS on thyroid function.

AIMS

Here we analyze several soluble and membrane-bound RAS-regulating aminopeptidase activities in thyroid gland from rats with mammary tumors and the relationship with the circulating levels of thyroid stimulating hormone (TSH) and free thyroxin (fT4).

MAIN METHODS

We analyze soluble and membrane-bound RAS-regulating aminopeptidase activities fluorometrically using their corresponding aminoacyl-β-naphthylamide as the substrate.

KEY FINDINGS

We have found in rats with mammary tumors a concomitant change of thyroid RAS-regulating enzymes and thyroid hormone production.

SIGNIFICANCE

We suggest that existence of alterations in the regulatory mechanisms mediated by the angiotensins of the local tissue RAS as a consequence of the carcinogenic process which could act alone or in combination with alterations at a higher level of regulation such as the hypothalamus-pituitary axis.

Orai3 constitutes a native store-operated calcium entry that regulates non small cell lung adenocarcinoma cell proliferation

Orai channels have been associated with cell proliferation, survival and metastasis in several cancers. The present study investigates the expression and the role of Orai3 in cell proliferation in non-small cell lung cancer (NSCLC). We show that Orai3 is over-expressed in cancer tissues as compared to the non-tumoral ones. Furthermore, Orai3 staining is stronger in high grade tumors. Pharmacological inhibition or knockdown of Orai3 significantly reduced store operated calcium entry (SOCE), inhibited cell proliferation and arrested cells of two NSCLC cell lines in G0/G1 phase. These effects were concomitant with a down-regulation of cyclin D1, cyclin E, CDK4 and CDK2 expression. Moreover, Orai3 silencing decreased Akt phosphorylation levels. In conclusion, Orai3 constitutes a native SOCE pathway in NSCLC that controls cell proliferation and cell cycle progression likely via Akt pathway.

Significance of the transient receptor potential canonical 2 (TRPC2) channel in the regulation of rat thyroid FRTL-5 cell proliferation, migration, adhesion and invasion

Mammalian transient receptor potential (TRP) channels are involved in many physiologically important processes. Here, we have studied the significance of the TRPC2 channel in the regulation of rat thyroid FRTL-5 cell proliferation, migration, adhesion and invasion, using stable TRPC2 (shTRPC2) knock-down cells. In the shTRPC2 cells, proliferation was decreased due to a prolonged G1/S cell cycle phase. The tumor suppressor p53 and the cyclin-dependant kinase inhibitors p27 and p21 were upregulated. Cell invasion, adhesion and migration were also attenuated in shTRPC2 cells, probably due to decreased activity of both Rac and calpain, and a decreased secretion and activity of matrix metalloproteinase 2. The attenuated proliferation, migration, invasion and ATP-evoked calcium entry was mimicked by overexpressing a non-conducting, truncated TRPC2 (TRPC2-DN) in wild type cells, and was reversed by overexpression of TRPC2-GFP in shTRPC2 cells. In conclusion, TRPC2 is an important regulator of rat thyroid cell function.

Functional coupling of TRPC2 cation channels and the calcium-activated anion channels in rat thyroid cells: implications for iodide homeostasis

The initial step in a synthesis of thyroid hormones is the uptake of iodide from the circulation. Iodide (I(-)) is transported into thyroid cells via a Na(+)/I(-) symporter (NIS), which is electrogenic and thus sensitive to alterations in membrane potential (V(m)). I(-) is then released to the lumen of thyroid follicles where the hormones are synthesised and stored. The mechanisms of I(-) release to follicle lumen are poorly characterised. Our whole-cell voltage clamp recordings revealed the presence of a Ca(2+) activated Cl(-) current (CaCC) in Fisher rat thyroid cell line 5 (FRTL-5). Transcripts of anoctamin 1 (ANO1) and anoctamin 10 (ANO10), putative molecular constituents of CaCC, were detected. The anion channels underlying CaCC are highly permeable to I(-). Both niflumic acid (NFA) and 2-aminoethyl diphenylborinate (2-APB), antagonists of CaCC and transient receptor potential channels, respectively, inhibited CaCC. Canonical transient receptor potential channel 2 (TRPC2) is the only TRPC member present in FRTL-5 cells. The activation rate of CaCC was markedly slower in shTRPC2 knock-down cells, indicating that Ca(2+) entry via TRPC2 contributes to CaCC activation. The uptake of iodide was enhanced and the resting V(m) was more depolarised in TRPC2 knock-down cells. We suggest that the interplay between TRPC2 and ANO1 may have dual effects on iodide transport, modulating I(-) release via ANO channels and I(-) uptake via the V(m) sensitive NIS.

Canonical transient receptor potential channel 2 (TRPC2) as a major regulator of calcium homeostasis in rat thyroid FRTL-5 cells: importance of protein kinase C δ (PKCδ) and stromal interaction molecule 2 (STIM2)

Mammalian non-selective transient receptor potential cation channels (TRPCs) are important in the regulation of cellular calcium homeostasis. In thyroid cells, including rat thyroid FRTL-5 cells, calcium regulates a multitude of processes. RT-PCR screening of FRTL-5 cells revealed the presence of TRPC2 channels only. Knockdown of TRPC2 using shRNA (shTRPC2) resulted in decreased ATP-evoked calcium peak amplitude and inward current. In calcium-free buffer, there was no difference in the ATP-evoked calcium peak amplitude between control cells and shTRPC2 cells. Store-operated calcium entry was indistinguishable between the two cell lines. Basal calcium entry was enhanced in shTRPC2 cells, whereas the level of PKCβ1 and PKCδ, the activity of sarco/endoplasmic reticulum Ca(2+)-ATPase, and the calcium content in the endoplasmic reticulum were decreased. Stromal interaction molecule (STIM) 2, but not STIM1, was arranged in puncta in resting shTRPC2 cells but not in control cells. Phosphorylation site Orai1 S27A/S30A mutant and non-functional Orai1 R91W attenuated basal calcium entry in shTRPC2 cells. Knockdown of PKCδ with siRNA increased STIM2 punctum formation and enhanced basal calcium entry but decreased sarco/endoplasmic reticulum Ca(2+)-ATPase activity in wild-type cells. Transfection of a truncated, non-conducting mutant of TRPC2 evoked similar results. Thus, TRPC2 functions as a major regulator of calcium homeostasis in rat thyroid cells.