Stanniocalcin 2 is a negative modulator of store-operated calcium entry

Stanniocalcin 2 governs cancer cell adaptation to nutrient insufficiency through alleviation of oxidative stress

Solid tumours often endure nutrient insufficiency during progression. How tumour cells adapt to temporal and spatial nutrient insufficiency remains unclear. We previously identified STC2 as one of the most upregulated genes in cells exposed to nutrient insufficiency by transcriptome screening, indicating the potential of STC2 in cellular adaptation to nutrient insufficiency. However, the molecular mechanisms underlying STC2 induction by nutrient insufficiency and subsequent adaptation remain elusive. Here, we report that STC2 protein is dramatically increased and secreted into the culture media by Gln-/Glc- deprivation. STC2 promoter contains cis-elements that are activated by ATF4 and p65/RelA, two transcription factors activated by a variety of cellular stress. Biologically, STC2 induction and secretion promote cell survival but attenuate cell proliferation during nutrient insufficiency, thus switching the priority of cancer cells from proliferation to survival. Loss of STC2 impairs tumour growth by inducing both apoptosis and necrosis in mouse xenografts. Mechanistically, under nutrient insufficient conditions, cells have increased levels of reactive oxygen species (ROS), and lack of STC2 further elevates ROS levels that lead to increased apoptosis. RNA-Seq analyses reveal STC2 induction suppresses the expression of monoamine oxidase B (MAOB), a mitochondrial membrane enzyme that produces ROS. Moreover, a negative correlation between STC2 and MAOB levels is also identified in human tumour samples. Importantly, the administration of recombinant STC2 to the culture media effectively suppresses MAOB expression as well as apoptosis, suggesting STC2 functions in an autocrine/paracrine manner. Taken together, our findings indicate that nutrient insufficiency induces STC2 expression, which in turn governs the adaptation of cancer cells to nutrient insufficiency through the maintenance of redox homoeostasis, highlighting the potential of STC2 as a therapeutic target for cancer treatment.

Orai1/STIMs modulators in pulmonary vascular diseases

Calcium (Ca2+) is a secondary messenger that regulates various cellular processes. However, Ca2+ mishandling could lead to pathological conditions. Orai1 is a Ca2+channel contributing to the store-operated calcium entry (SOCE) and plays a critical role in Ca2+ homeostasis in several cell types. Dysregulation of Orai1 contributed to severe combined immune deficiency syndrome, some cancers, pulmonary arterial hypertension (PAH), and other cardiorespiratory diseases. During its activation process, Orai1 is mainly regulated by stromal interacting molecule (STIM) proteins, especially STIM1; however, many other regulatory partners have also been recently described. Increasing knowledge about these regulatory partners provides a better view of the downstream signalling pathways of SOCE and offers an excellent opportunity to decipher Orai1 dysregulation in these diseases. These proteins participate in other cellular functions, making them attractive therapeutic targets. This review mainly focuses on Orai1 regulatory partners in the physiological and pathological conditions of the pulmonary circulation and inflammation.

Stanniocalcin 2 governs cancer cell adaptation to nutrient insufficiency through alleviation of oxidative stress

Solid tumours often endure nutrient insufficiency during progression. How tumour cells adapt to temporal and spatial nutrient insufficiency remains unclear. We previously identified STC2 as one of the most upregulated genes in cells exposed to nutrient insufficiency by transcriptome screening, indicating the potential of STC2 in cellular adaptation to nutrient insufficiency. However, the molecular mechanisms underlying STC2 induction by nutrient insufficiency and subsequent adaptation remain elusive. Here, we report that STC2 protein is dramatically increased and secreted into the culture media by Gln-/Glc-deprivation. STC2 promoter contains cis-elements that are activated by ATF4 and p65/RelA, two transcription factors activated by a variety of cellular stress. Biologically, STC2 induction and secretion promote cell survival but attenuate cell proliferation during nutrient insufficiency, thus switching the priority of cancer cells from proliferation to survival. Loss of STC2 impairs tumour growth by inducing both apoptosis and necrosis in mouse xenografts. Mechanistically, under nutrient insufficient conditions, cells have increased levels of reactive oxygen species (ROS), and lack of STC2 further elevates ROS levels that lead to increased apoptosis. RNA-Seq analyses reveal STC2 induction suppresses the expression of monoamine oxidase B (MAOB), a mitochondrial membrane enzyme that produces ROS. Moreover, a negative correlation between STC2 and MAOB levels is also identified in human tumour samples. Importantly, the administration of recombinant STC2 to the culture media effectively suppresses MAOB expression as well as apoptosis, suggesting STC2 functions in an autocrine/paracrine manner. Taken together, our findings indicate that nutrient insufficiency induces STC2 expression, which in turn governs the adaptation of cancer cells to nutrient insufficiency through the maintenance of redox homeostasis, highlighting the potential of STC2 as a therapeutic target for cancer treatment.

FicD Sensitizes Cellular Response to Glucose Fluctuations in Mouse Embryonic Fibroblasts

During homeostasis, the endoplasmic reticulum (ER) maintains productive transmembrane and secretory protein folding that is vital for proper cellular function. The ER-resident HSP70 chaperone, BiP, plays a pivotal role in sensing ER stress to activate the unfolded protein response (UPR). BiP function is regulated by the bifunctional enzyme FicD that mediates AMPylation and deAMPylation of BiP in response to changes in ER stress. AMPylated BiP acts as a molecular rheostat to regulate UPR signaling, yet little is known about the molecular consequences of FicD loss. In this study, we investigate the role of FicD in mouse embryonic fibroblast (MEF) response to pharmacologically and metabolically induced ER stress. We find differential BiP AMPylation signatures when comparing robust chemical ER stress inducers to physiological glucose starvation stress and recovery. Wildtype MEFs respond to pharmacological ER stress by downregulating BiP AMPylation. Conversely, BiP AMPylation in wildtype MEFs increases upon metabolic stress induced by glucose starvation. Deletion of FicD results in widespread gene expression changes under baseline growth conditions. In addition, FicD null MEFs exhibit dampened UPR signaling, altered cell stress recovery response, and unconstrained protein secretion. Taken together, our findings indicate that FicD is important for tampering UPR signaling, stress recovery, and the maintenance of secretory protein homeostasis.

Significance Statement

The chaperone BiP plays a key quality control role in the endoplasmic reticulum, the cellular location for the production, folding, and transport of secreted proteins. The enzyme FicD regulates BiP's activity through AMPylation and deAMPylation. Our study unveils the importance of FicD in regulating BiP and the unfolded protein response (UPR) during stress. We identify distinct BiP AMPylation signatures for different stressors, highlighting FicD's nuanced control. Deletion of FicD causes widespread gene expression changes, disrupts UPR signaling, alters stress recovery, and perturbs protein secretion in cells. These observations underscore the pivotal contribution of FicD for preserving secretory protein homeostasis. Our findings deepen the understanding of FicD's role in maintaining cellular resilience and open avenues for therapeutic strategies targeting UPR-associated diseases.

STC2 is a potential biomarker of hepatocellular carcinoma with its expression being upregulated in Nrf1α-deficient cells, but downregulated in Nrf2-deficient cells

Nrf1 (encoded by Nfe2l1) and Nrf2 (encoded by Nfe2l2), as two key members of the CNC-bZIP transcription factor, exhibit significant functional differences in their pathophysiology. Our previous findings demonstrated that loss of Nrf1α (i.e., a full-length isoform of Nrf1) promotes HepG2-derived tumor growth in xenograft mice, but malgrowth of the xenograft tumor is significantly suppressed by knockout of Nrf2. To gain insights into the mechanism underlying such marked distinctions in their pathologic phenotypes, we mined transcriptome data from liver cancer in the TCGA database to establish a prognostic model and calculate predicted risk scores for each cell line. The results revealed that knockout of Nrf1α markedly increased the risk score in HepG2 cells, whereas the risk score was reduced by knockout of Nrf2. Notably, stanniocalcin 2 (STC2), a biomarker associated with liver cancer, that is upexpressed in hepatocellular carcinoma (HCC) tissues with a reduction in the overall survival ratio of those patients. We observed increased expression levels of STC2 in Nrf1α-/- cells but decreased expression in Nrf2-/- cells. These findings suggested that STC2 may play a role in mediating the distinction between Nrf1α-/- and Nrf2-/-. Such potential function of STC2 was further corroborated through a series of experiments combined with transcriptomic sequencing. The results revealed that STC2 functions as a dominant tumor-promoter, because the STC2-leading increases in clonogenicity of hepatoma cells and malgrowth of relevant xenograft tumor were almost completely abolished in STC2-/- cells. Together, these demonstrate that STC2 could be paved as a potential therapeutic target, albeit as a diagnostic marker, for HCC.

Role of ERK1/2 Signaling in Cinnabarinic Acid-Driven Stanniocalcin 2-Mediated Protection against Alcohol-Induced Apoptosis

We have previously shown that a bona fide aryl hydrocarbon receptor (AhR) agonist, cinnabarinic acid (CA), protects against alcohol-induced hepatocyte apoptosis via activation of a novel AhR target gene, stanniocalcin 2 (Stc2). Stc2 translates to a secreted disulfide-linked hormone, STC2, known to function in cell development, calcium and phosphate regulation, angiogenesis, and antiapoptosis-albeit the comprehensive mechanism by which the CA-AhR-STC2 axis confers antiapoptosis is yet to be characterized. In this study, using RNA interference library screening, downstream antiapoptotic molecular signaling components involved in CA-induced STC2-mediated protection against ethanol-induced apoptosis were investigated. RNA interference library screening of kinases and phosphatases in Hepa1 cells and subsequent pathway analysis identified mitogen-activated protein kinase (MAPK) signaling as a critical molecular pathway involved in CA-mediated protection. Specifically, phosphorylation of ERK1/2 was induced in response to CA treatment without alterations in p38 and JNK signaling pathways. Silencing Stc2 in Hepa1 cells and in vivo experiments performed in Stc2-/- (Stc2 knockout) mice, which failed to confer CA-mediated protection against ethanol-induced apoptosis, showed abrogation of ERK1/2 activation, underlining the significance of ERK1/2 signaling in CA-STC2-mediated protection. In conclusion, activation of ERK1/2 signaling in CA-driven AhR-dependent Stc2-mediated protection represents a novel mechanism of protection against acute alcohol-induced apoptosis. SIGNIFICANCE STATEMENT: Previous studies have shown the role of stanniocalcin 2 (Stc2) in cinnabarinic acid (CA)-mediated protection against alcohol-induced apoptosis. Here, using RNA interference library screening and subsequent in vivo studies, the functional significance of ERK1/2 activation in CA-induced Stc2-mediated protection against acute ethanol-induced apoptosis was identified. This study is thus significant as it illustrates a comprehensive downstream mechanism by which CA-induced Stc2 protects against alcoholic liver disease.

The Cytoplasmic Region of SARAF Reduces Triple-Negative Breast Cancer Metastasis through the Regulation of Store-Operated Calcium Entry

Triple-negative breast cancer has a poor prognosis and is non-responsive to first-line therapies; hence, new therapeutic strategies are needed. Enhanced store-operated Ca2+ entry (SOCE) has been widely described as a contributing factor to tumorigenic behavior in several tumor types, particularly in breast cancer cells. SOCE-associated regulatory factor (SARAF) acts as an inhibitor of the SOCE response and, therefore, can be a potential antitumor factor. Herein, we generated a C-terminal SARAF fragment to evaluate the effect of overexpression of this peptide on the malignancy of triple-negative breast cancer cell lines. Using both in vitro and in vivo approaches, we showed that overexpression of the C-terminal SARAF fragment reduced proliferation, cell migration, and the invasion of murine and human breast cancer cells by decreasing the SOCE response. Our data suggest that regulating the activity of the SOCE response via SARAF activity might constitute the basis for further alternative therapeutic strategies for triple-negative breast cancer.

Stanniocalcin 2 drives malignant transformation of human glioblastoma cells by targeting SNAI2 and Matrix Metalloproteinases

Glioblastoma multiforme (GBM) is the most malignant brain tumor and is refractory to conventional therapies. Although previous studies have proposed that the interaction between gene mutations and the external environment leads to the occurrence of GBM, the pathogenesis of GBM is still unclear and much remains to be studied. Herein, we show an association between human glycoprotein stanniocalcin-2 (STC2) and aggressive GBM progression, and demonstrate the underlying mechanism. Elevated STC2 expression and secretion greatly increase GBM cell growth and invasive phenotypes. Mechanistically, both, conditioned media (CM) containing STC2 and recombinant STC2, can induce the transformation of GBM cells into more malignant phenotypes by upregulating the expression of the epithelial-mesenchymal transition transcription factor, snail family transcription repressor 2 (SNAI2) as well as matrix metalloproteinases (MMPs). Moreover, we further demonstrate that the oncogenic function of STC2 in GBM is mediated through the MAPK signaling pathway. Collectively, these results identify the mechanism of STC2 targeting SNAI2 and MMPs through the MAPK pathway in GBM, and provide insights into a potential therapeutic strategy for GBM.

Stanniocalcin2, but Not Stanniocalcin1, Responds to Hypoxia in a HIF1-Dependent Manner in the Retina

The quest for neuroprotective factors that can prevent or slow down the progression of retinal degeneration is still ongoing. Acute hypoxic stress has been shown to provide transient protection against subsequent damage in the retina. Stanniocalcins – STC1 and STC2 – are secreted glycoproteins that are hypoxia-regulated and were shown to be cytoprotective in various in vitro studies. Hence, we investigated the expression of stanniocalcins in the normal, degenerating and hypoxic retina. We show that the expression of Stc1 and Stc2 in the retina was detectable as early as postnatal day 10 and persisted during aging. Retinal expression of Stc2, but not Stc1, was induced in mice in an in vivo model of acute hypoxia and a genetic model of chronic hypoxia. Furthermore, we show that HIF1, not HIF2, is responsible for regulating Stc2 in cells with the molecular response to hypoxia activated due to the absence of von Hippel Lindau protein. Surprisingly, Stc2 was not normally expressed in photoreceptors but in the inner retina, as shown by laser capture microdissection and immunofluorescence data. The expression of both Stc1 and Stc2 remained unchanged in the degenerative retina with an almost complete loss of photoreceptors, confirming their expression in the inner retina. However, the absence of either Stc1 or Stc2 had no effect on retinal architecture, as was evident from retinal morphology of the respective knockout mice. Taken together our data provides evidence for the differential regulation of STC1 and STC2 in the retina and the prospect of investigating STC2 as a retinal neuroprotective factor.

Stanniocalcin 2 (STC2): a universal tumour biomarker and a potential therapeutical target

Stanniocalcin 2 (STC2) is a glycoprotein which is expressed in a broad spectrum of tumour cells and tumour tissues derived from human breast, colorectum, stomach, esophagus, prostate, kidney, liver, bone, ovary, lung and so forth. The expression of STC2 is regulated at both transcriptional and post-transcriptional levels; particularly, STC2 is significantly stimulated under various stress conditions like ER stress, hypoxia and nutrient deprivation. Biologically, STC2 facilitates cells dealing with stress conditions and prevents apoptosis. Importantly, STC2 also promotes the development of acquired resistance to chemo- and radio- therapies. In addition, multiple groups have reported that STC2 overexpression promotes cell proliferation, migration and immune response. Therefore, the overexpression of STC2 is positively correlated with tumour growth, invasion, metastasis and patients' prognosis, highlighting its potential as a biomarker and a therapeutic target. This review focuses on discussing the regulation, biological functions and clinical importance of STC2 in human cancers. Future perspectives in this field will also be discussed.

Cinnabarinic Acid-Induced Stanniocalcin 2 Confers Cytoprotection against Alcohol-Induced Liver Injury

We recently identified upregulation of a novel aryl hydrocarbon receptor (AhR) target gene, stanniocalcin 2 (STC2), by an endogenous AhR agonist, cinnabarinic acid (CA). STC2 is a disulfide-linked homodimeric secreted glycoprotein that plays a role in various physiologic processes, including cell metabolism, inflammation, endoplasmic reticulum (ER) and oxidative stress, calcium regulation, cell proliferation, and apoptosis. Our previous studies have confirmed that CA-induced AhR-dependent STC2 expression was able to confer cytoprotection both in vitro and in vivo in response to injury induced by variety of ER/oxidative insults. Here, we used mouse models of chronic and acute ethanol feeding and demonstrated that upregulation of STC2 by CA was critical for cytoprotection. In STC2 knockout mice (STC2-/-), CA failed to protect against both acute as well as chronic-plus-binge ethanol-induced liver injury, whereas re-expression of STC2 in the liver using in vivo gene delivery restored cytoprotection against injury based on measures of apoptosis and serum levels of liver enzymes, underlining STC2's indispensable function in cell survival. In conclusion, the identification of STC2 as an AhR target gene receptive to CA-mediated endogenous AhR signaling and STC2's role in providing cytoprotection against liver injury represents a key finding with potentially significant therapeutic implications. SIGNIFICANCE STATEMENT: We recently identified stanniocalcin 2 (STC2) as a novel aryl hydrocarbon receptor (AhR) target gene regulated by endogenous AhR agonist and tryptophan metabolite, cinnabarinic acid (CA). Here, we showed that CA-induced STC2 expression conferred cytoprotection against apoptosis, steatosis, and liver injury in chronic as well as acute models of ethanol feeding. Therefore, this study will prove instrumental in developing CA as a promising lead compound for future drug development against hepatic diseases.

CRACking the Molecular Regulatory Mechanism of SOCE during Platelet Activation in Thrombo-Occlusive Diseases

Thrombo-occlusive diseases such as myocardial infarction, ischemic stroke and deep vein thrombosis with subsequent pulmonary embolism still represent a major health burden worldwide. Besides the cells of the vasculature or other hematopoietic cells, platelets are primarily responsible for the development and progression of an occluding thrombus. The activation and function of platelets crucially depend on free cytosolic calcium (Ca2+) as second messenger, which modulates platelet secretion, aggregation and thrombus formation. Ca2+ is elevated upon platelet activation by release of Ca2+ from intracellular stores thus triggering of the subsequent store-operated Ca2+ entry (SOCE), which is facilitated by Ca2+ release-activated channels (CRACs). In general, CRACs are assembled by the pore-forming unit Orai in the plasma membrane and the Ca2+-sensing stromal interaction molecule (STIM) in the endoplasmic reticulum after the depletion of internal Ca2+ stores. In the last few years, there is a growing body of the literature demonstrating the importance of STIM and Orai-mediated mechanism in thrombo-occlusive disorders. Thus, this review provides an overview of the recent understanding of STIM and Orai signaling in platelet function and its implication in the development and progression of ischemic thrombo-occlusive disorders. Moreover, potential pharmacological implications of STIM and Orai signaling in platelets are anticipated and discussed in the end.

Immunohistochemical Expression of Stanniocalcin 2 in Colorectal Cancer: A Retrospective Egyptian Study

BACKGROUND & OBJECTIVE

Colorectal cancer is the third most common cause of cancer death worldwide. Stanniocalcin 2 (STC2) is a glycoprotein hormone over-expressed in many human cancers where it regulates tumor progression and invasion. Evaluating its expression in colorectal cancer and its relation with different clinicopathological parameters can provide valuable information about its role in colorectal cancer progression and behavior.

METHODS

This retrospective study was conducted on tissue samples of colorectal cancer. The STC2 immunohistochemical expression was detected and evaluated in 60 cases of colorectal cancer tissue samples of formalin-fixed and paraffin-embedded blocks. Then statistical analysis was performed to assess the relationship between its expression level and several clinicopathological parameters in the studied cases.

RESULTS

Statistically significant associations were found between the high level of STC2 immunohistochemical expression and histological tumor grade (P<0.001), tumor depth of invasion (T stage) (P=0.004), lymph node metastasis (N stage) (P=0.001), tumor Dukes' stage (P<0.001), the presence of lymphovascular invasion (P<0.001), and perineural invasion (P<0.001).

CONCLUSION

STC2 over-expression in colorectal cancer may be associated with more aggressive tumor behavior including increased tumor invasion, higher histological grade, higher rate of nodal metastasis and increased incidence of lymphovascular and perineural invasions. These data suggest a potential role for STC2 as a predictive biomarker for tumor behavior in colorectal cancer patients.

Plasma Membrane and Organellar Targets of STIM1 for Intracellular Calcium Handling in Health and Neurodegenerative Diseases

Located at the level of the endoplasmic reticulum (ER) membrane, stromal interacting molecule 1 (STIM1) undergoes a complex conformational rearrangement after depletion of ER luminal Ca²⁺. Then, STIM1 translocates into discrete ER-plasma membrane (PM) junctions where it directly interacts with and activates plasma membrane Orai1 channels to refill ER with Ca²⁺. Furthermore, Ca²⁺ entry due to Orai1/STIM1 interaction may induce canonical transient receptor potential channel 1 (TRPC1) translocation to the plasma membrane, where it is activated by STIM1. All these events give rise to store-operated calcium entry (SOCE). Besides the main pathway underlying SOCE, which mainly involves Orai1 and TRPC1 activation, STIM1 modulates many other plasma membrane proteins in order to potentiate the influxof Ca²⁺. Furthermore, it is now clear that STIM1 may inhibit Ca²⁺ currents mediated by L-type Ca²⁺ channels. Interestingly, STIM1 also interacts with some intracellular channels and transporters, including nuclear and lysosomal ionic proteins, thus orchestrating organellar Ca²⁺ homeostasis. STIM1 and its partners/effectors are significantly modulated in diverse acute and chronic neurodegenerative conditions. This highlights the importance of further disclosing their cellular functions as they might represent promising molecular targets for neuroprotection.

Epithelial expression and role of secreted STC1 on asthma airway hyperresponsiveness through calcium channel modulation

BACKGROUND

Asthma is characterized by airway hyperresponsiveness (AHR), inflammation, and airway remodeling. Airway hyperresponsiveness results from enhanced airway smooth muscle (ASM) contraction potentially under the control of an epithelium-derived relaxing factor (EpDRF). However, relatively rare is known about EpDRF. We aimed to elucidate the role of epithelium-derived stanniocalcin-1 (STC1) on AHR and ASM contraction.

METHODS

Stanniocalcin-1 levels in the serum of asthmatic patients and healthy volunteers and in bronchoalveolar lavage fluid (BALF) from ovalbumin (OVA)-challenged mice were measured by ELISA. The effects of exogenous STC1 on AHR and on inflammation were examined in mice. IL-13 modulation of STC1 mRNA and protein levels was studied in human bronchial epithelial cell lines (16HBE). The function of STC1 on Ca²⁺ influx and ASM contraction was examined ex vivo.

RESULTS

Serum STC1 was decreased in asthma (n = 93) compared with healthy volunteers (1071 ± 30.4 vs 1414 ± 75.1 pg/ml, p < 0.0001, n = 23) and correlated with asthma control (p = 0.0270), lung function (FEV1, p = 0.0130), and serum IL-13 levels (p = 0.0009). Treatment of ten asthmatic subjects with inhaled corticosteroids/long-acting beta2-agonists (ICS/LABA) for 1 year enhanced STC1 expression which correlated with improved asthma control (p = 0.022). STC1 was mainly expressed in bronchial epithelium and intranasal administration of recombinant human STC1 (rhSTC1) reduced AHR and inflammation in mice. IL-13 suppressed STC1 release from 16HBE, whereas rhSTC1 blocked store-operated Ca²⁺ entry (SOCE) by suppressing stromal interaction molecule 1 (STIM1) and further inhibited ASM cell contractility by suppressing Ca²⁺ -dependent myosin light chain (MLC) phosphorylation.

CONCLUSION

Our data indicate that STC1 deficiency in asthmatic airways promotes STIM1 hyperactivity, enhanced ASM contraction, and AHR. STC1 may be a candidate EpDRF.

Transcriptome Analysis Reveals the Role of Cellular Calcium Disorder in Varicella Zoster Virus-Induced Post-Herpetic Neuralgia

As a typical neuropathic pain, post-herpetic neuralgia (PHN) is a common complication of herpes zoster (HZ), which seriously affects the normal life and work of patients. The unclear pathogenesis and lack of effective drugs make the clinical efficacy of PHN unsatisfactory. Here, we obtained the transcriptome profile of neuroblastoma cells (SH-SY5Y) and DRG in rats infected with varicella zoster virus (VZV) by transcriptome sequencing (RNA-Seq) combined with publicly available gene array data sets. Next, the data processing of the transcriptome map was analyzed using bioinformatics methods, including the screening of differentially expressed genes (DEGs), Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Finally, real-time fluorescent quantitative PCR (qRT-PCR) was used to detect the expression of calcium-related genes, and calcium fluorescent probes and calcium colorimetry were used to evaluate the distribution and content of calcium ions in cells after VZV infection. Transcriptome data analysis (GO and KEGG enrichment analysis) showed that calcium disorder played an important role in SH-SY5Y cells infected by VZV and dorsal root ganglion (DRG) of the PHN rat model. The results of qRT-PCR showed that the expression levels of calcium-related genes BHLHA15, CACNA1F, CACNG1, CHRNA9, and STC2 were significantly upregulated, while the expression levels of CHRNA10, HRC, and TNNT3 were significantly downregulated in SH-SY5Y cells infected with VZV. Our calcium fluorescent probe and calcium colorimetric test results showed that VZV could change the distribution of calcium ions in infected cells and significantly increase the intracellular calcium content. In conclusion, our results revealed that the persistence of calcium disorder caused by VZV in nerve cells might be a crucial cause of herpetic neuralgia, and a potential target for clinical diagnosis and treatment of PHN.

Effects of stanniocalcin hormones on rat hepatic glucose homeostasis under fed and fasted conditions

To test the hypothesis of conservation of stanniocalcin 1 and 2 (STC-1; STC-2) metabolic functions in vertebrates, we performed an in vitro study to determine if these hormones are implicated in regulation of the gluconeogenesis pathway, glycogen synthesis, and ¹⁴C-glucose conversion to ¹⁴CO₂ in livers from fed and fasting rats (Rattus norvegicus). Stc1 and Stc2 gene expressions increased in the liver after fasting. STC-1 participated in the regulation of the hepatic gluconeogenesis pathway in rats when the precursor was ¹⁴C-lactate. STC-2 demonstrated variational signaling on rat hepatic gluconeogenesis activity and Pck1 gene expression, decreasing levels in the fed state when the substrate was ¹⁴C-alanine and increasing levels during fasting when the substrate was ¹⁴C-lactate. At the concentrations used in this study, STC-1 and STC-2 did not affect glycogen concentration and synthesis from ¹⁴C-glucose or ¹⁴C-glucose conversion to ¹⁴CO₂ in the livers from fed or fasting rats. These findings highlight the role of stanniocalcins in the hepatic gluconeogenesis pathway in mammals and confirm the conservation of STC-1 and STC-2 metabolic functions in the vertebrates.

PI4KIIIβ is a therapeutic target in chromosome 1q-amplified lung adenocarcinoma

Heightened secretion of protumorigenic effector proteins is a feature of malignant cells. Yet, the molecular underpinnings and therapeutic implications of this feature remain unclear. Here, we identify a chromosome 1q region that is frequently amplified in diverse cancer types and encodes multiple regulators of secretory vesicle biogenesis and trafficking, including the Golgi-dedicated enzyme phosphatidylinositol (PI)-4-kinase IIIβ (PI4KIIIβ). Molecular, biochemical, and cell biological studies show that PI4KIIIβ-derived PI-4-phosphate (PI4P) synthesis enhances secretion and accelerates lung adenocarcinoma progression by activating Golgi phosphoprotein 3 (GOLPH3)-dependent vesicular release from the Golgi. PI4KIIIβ-dependent secreted factors maintain 1q-amplified cancer cell survival and influence prometastatic processes in the tumor microenvironment. Disruption of this functional circuitry in 1q-amplified cancer cells with selective PI4KIIIβ antagonists induces apoptosis and suppresses tumor growth and metastasis. These results support a model in which chromosome 1q amplifications create a dependency on PI4KIIIβ-dependent secretion for cancer cell survival and tumor progression.

In Vivo Gene Delivery of STC2 Promotes Axon Regeneration in Sciatic Nerves

Neurons are vulnerable to injury, and failure to activate self-protective systems after injury leads to neuronal death. However, sensory neurons in dorsal root ganglions (DRGs) mostly survive and regenerate their axons. To understand the mechanisms of the neuronal injury response, we analyzed the injury-responsive transcriptome and found that Stc2 is immediately upregulated after axotomy. Stc2 is required for axon regeneration in vivo and in vitro, indicating that Stc2 is a neuronal factor regulating axonal injury response. The application of the secreted stanniocalcin 2 to injured DRG neurons promotes regeneration. Stc2 thus represents a potential secretory protein with a feedback function regulating regeneration. Finally, the in vivo gene delivery of STC2 increases regenerative growth after injury in peripheral nerves in mice. These results suggest that Stc2 is an injury-responsive gene required for axon regeneration and a potential target for developing therapeutic applications.

More Than Just Simple Interaction between STIM and Orai Proteins: CRAC Channel Function Enabled by a Network of Interactions with Regulatory Proteins

The calcium-release-activated calcium (CRAC) channel, activated by the release of Ca2+ from the endoplasmic reticulum (ER), is critical for Ca2+ homeostasis and active signal transduction in a plethora of cell types. Spurred by the long-sought decryption of the molecular nature of the CRAC channel, considerable scientific effort has been devoted to gaining insights into functional and structural mechanisms underlying this signalling cascade. Key players in CRAC channel function are the Stromal interaction molecule 1 (STIM1) and Orai1. STIM1 proteins span through the membrane of the ER, are competent in sensing luminal Ca2+ concentration, and in turn, are responsible for relaying the signal of Ca2+ store-depletion to pore-forming Orai1 proteins in the plasma membrane. A direct interaction of STIM1 and Orai1 allows for the re-entry of Ca2+ from the extracellular space. Although much is already known about the structure, function, and interaction of STIM1 and Orai1, there is growing evidence that CRAC under physiological conditions is dependent on additional proteins to function properly. Several auxiliary proteins have been shown to regulate CRAC channel activity by means of direct interactions with STIM1 and/or Orai1, promoting or hindering Ca2+ influx in a mechanistically diverse manner. Various proteins have also been identified to exert a modulatory role on the CRAC signalling cascade although inherently lacking an affinity for both STIM1 and Orai1. Apart from ubiquitously expressed representatives, a subset of such regulatory mechanisms seems to allow for a cell-type-specific control of CRAC channel function, considering the rather restricted expression patterns of the specific proteins. Given the high functional and clinical relevance of both generic and cell-type-specific interacting networks, the following review shall provide a comprehensive summary of regulators of the multilayered CRAC channel signalling cascade. It also includes proteins expressed in a narrow spectrum of cells and tissues that are often disregarded in other reviews of similar topics.

Small RNA sequencing reveals a novel tsRNA-06018 playing an important role during adipogenic differentiation of hMSCs

Transfer RNA-derived small RNAs (tsRNAs), a novel type of non-coding RNA derivative, are able to regulate a wide range of biological processes. What role these tsRNAs play in the regulation of human bone marrow mesenchymal stem cell (hMSCs) adipogenic differentiation remains uncertain. We induced the adipogenic differentiation of human bone marrow mesenchymal cells (hMSCs) and then performed small RNA transcriptomic sequencing, leading us to identify tsRNA-06018 as a target of interest based upon resultant the tsRNA expression profiles. When tsRNA-06018 was knocked down, this led to the inhibition of adipogenesis and a decrease in adipogenic marker expression. When STC2 was overexpressed, this impaired the adipogenic differentiation of these cells. We further used luciferase reporter assays to confirm that tsRNA-06018 directly binds the 3'-untranslated region (3'-UTR) of STC2. In addition, we determined that both knocking down tsRNA-06018 and overexpressing STC2 increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation within cells. We also assessed that the adipogenic differentiation of hMSCs in which tsRNA-06018 was knocked down was further enhanced upon the addition of the ERK1/2 inhibitor U0126 as compared tsRNA-06018 knockdown alone. Taken together, using small RNA sequencing we profiled tsRNAs in hMSCs during the process of adipogenesis, leading us to identify tsRNA-06018 as a novel regulator of this differentiation process. This tsRNA was able to regulate adipogenic differentiation by targeting STC2 via the ERK1/2 signalling pathway.

The Transcription Factor p63 Is a Direct Effector of IL-4- and IL-13-Mediated Repression of Keratinocyte Differentiation

Atopic Dermatitis is an inflammatory skin disease associated with broad defects in skin barrier function caused by increased levels of type-2 cytokines (IL-4 and IL-13) that repress keratinocyte (KC) differentiation. Although crucial in mediating allergic disease, the mechanisms for gene repression induced by type-2 cytokines remain unclear. In this study, we determined that gene repression requires the master regulator of the epidermal differentiation program, p63. We found that type-2 cytokine-mediated inhibition of the expression of genes involved in early KC differentiation, including keratin 1, keratin 10, and DSC-1, is reversed by p63 blockade. Type-2 cytokines, through p63, also regulate additional genes involved in KC differentiation, including CHAC-1, STC2, and CALML5. The regulation of the expression of these genes is ablated by p63 small interfering RNA as well. In addition, we found that IL-4 and IL-13 and Staphylococcus aureus lipoteichoic acid work in combination through p63 to further suppress the early KC differentiation program. Finally, we found that IL-4 and IL-13 also inhibit the activity of Notch, a transcription factor required to induce early KC differentiation. In conclusion, type-2 cytokine-mediated gene repression and blockade of KC differentiation are multifactorial, involving pathways that converge on transcription factors critical for epidermal development, p63 and Notch.

Modulation of Cerebral Store-operated Calcium Entry-regulatory Factor (SARAF) and Peripheral Orai1 Following Focal Cerebral Ischemia and Preconditioning in Mice

Store-operated Ca²⁺ entry (SOCE) contributes to Ca²⁺ refilling of endoplasmic reticulum (ER), but also provides Ca²⁺ influx involved in physiological and pathological signalling functions. Upon depletion of Ca²⁺ store, the sensor protein stromal interaction molecule (STIM) activates Orai1, forming an ion-conducting pore highly selective for Ca²⁺. SOCE-associated regulatory factor (SARAF) associates with STIM1 to facilitate a slow form of Ca²⁺-dependent inactivation of SOCE or interacts with Orai1 to stimulate SOCE in STIM1-independent manner. We have investigated whether cerebral ischemic damage and neuroprotection conferred by ischemic preconditioning (PC) in mouse are associated with changes in the expression of the molecular components of SOCE. Ischemic PC induced by 15-min occlusion of the middle cerebral artery (MCAo) resulted in significant amelioration of histological and functional outcomes produced, 72 h later, by a more severe ischemia (1 h MCAo). Neither ischemia, nor PC affected the expression of Orai1 in the frontoparietal cortex. However, the number of Orai1-immunopositive cells, mostly corresponding to Ly-6G+ neutrophils, was significantly elevated in the blood after the ischemic insult, regardless of previous PC. The expression of Stim1 and SARAF, mainly localised in NeuN-immunopositive neurons, was reduced in the ischemic cortex. Interestingly, neuroprotection by ischemic PC prevented the reduction of SARAF expression in the lesioned cortex and this could be interpreted as a compensatory mechanism to restore ER Ca²⁺ refilling in neurons in the absence of STIM1. Thus, preventing SARAF downregulation may represent a pivotal mechanism implicated in neuroprotection provided by ischemic PC and should be exploited as an original target for novel stroke therapies.

Deimination Protein Profiles in Alligator mississippiensis Reveal Plasma and Extracellular Vesicle-Specific Signatures Relating to Immunity, Metabolic Function, and Gene Regulation

Alligators are crocodilians and among few species that endured the Cretaceous-Paleogene extinction event. With long life spans, low metabolic rates, unusual immunological characteristics, including strong antibacterial and antiviral ability, and cancer resistance, crocodilians may hold information for molecular pathways underlying such physiological traits. Peptidylarginine deiminases (PADs) are a group of calcium-activated enzymes that cause posttranslational protein deimination/citrullination in a range of target proteins contributing to protein moonlighting functions in health and disease. PADs are phylogenetically conserved and are also a key regulator of extracellular vesicle (EV) release, a critical part of cellular communication. As little is known about PAD-mediated mechanisms in reptile immunology, this study was aimed at profiling EVs and protein deimination in Alligator mississippiensis. Alligator plasma EVs were found to be polydispersed in a 50-400-nm size range. Key immune, metabolic, and gene regulatory proteins were identified to be posttranslationally deiminated in plasma and plasma EVs, with some overlapping hits, while some were unique to either plasma or plasma EVs. In whole plasma, 112 target proteins were identified to be deiminated, while 77 proteins were found as deiminated protein hits in plasma EVs, whereof 31 were specific for EVs only, including proteins specific for gene regulatory functions (e.g., histones). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed KEGG pathways specific to deiminated proteins in whole plasma related to adipocytokine signaling, while KEGG pathways of deiminated proteins specific to EVs included ribosome, biosynthesis of amino acids, and glycolysis/gluconeogenesis pathways as well as core histones. This highlights roles for EV-mediated export of deiminated protein cargo with roles in metabolism and gene regulation, also related to cancer. The identification of posttranslational deimination and EV-mediated communication in alligator plasma revealed here contributes to current understanding of protein moonlighting functions and EV-mediated communication in these ancient reptiles, providing novel insight into their unusual immune systems and physiological traits. In addition, our findings may shed light on pathways underlying cancer resistance, antibacterial and antiviral resistance, with translatable value to human pathologies.

New Insights Into Physiological and Pathophysiological Functions of Stanniocalcin 2

Stanniocalcin, a glycosylated peptide hormone, first discovered in a bony fish has originally been shown to play critical role in calcium and phosphate homeostasis. Two paralogs of stanniocalcin (STC1 and STC2) identified in mammals are widely expressed in variety of tissues. This review provides historical perspective on the discovery of fish and mammalian stanniocalcin, describes molecular regulation of STC2 gene, catalogs distribution as well as expression of STC2 in tissues, and provides key structural information known till date regarding mammalian STC2. Additionally, this mini review summarizes pivotal functions of STC2 in calcium and phosphate regulation, cytoprotection, cell development, and angiogenesis. Finally, STC2's role as a novel marker for human cancers has also been outlined. Reviewing these studies will provide an opportunity to understand STC2's structure, biological functions as well as key molecular pathways involving STC2, which will help us design innovative therapeutic interventions using this novel hormone.

Stanniocalcin-1 and -2 effects on glucose and lipid metabolism in white adipose tissue from fed and fasted rats

Stanniocalcin-1 and -2 belong to a family of molecules that exhibit both paracrine and autocrine effects in mammalian cells. Human stanniocalcin-1 (hSTC-1) is expressed in a wide range of tissues, including white adipose tissue. In fed rats, hSTC-1 increases carbon flux from glucose to lipids in retroperitoneal white adipose tissue. Human stanniocalcin-2 (hSTC-2) is expressed in almost all tissues and regulates various biological processes. The aim of this work was to study the action of hSTC-1 and hSTC-2 in the lipid and glucose metabolism of epididymal white adipose tissue (eWAT) in rats in different nutritional states. This study shows for the first time an opposite effect of hSTC-1 and hSTC-2 on glyceride-glycerol generation from glucose in eWAT of fed rats. hSTC-1 stimulated the storage of triacylglycerol in eWAT in the postprandial period, increasing glucose uptake and glyceride-glycerol generation from 14C-glucose. hSTC-2 decreased triacylglycerol synthesis, reducing glyceride-glycerol generation from 14C-glucose, direct phosphorylation of glycerol, and fatty acid synthesis from 14C-glucose in eWAT of fed rats. However, both hormones increased glucose uptake in fed and fasting states. These findings provide evidence for a direct role of hSTC-1 and hSTC-2 in the regulation of lipid and glucose metabolism in eWAT of rats.

ER stress activation in the intestinal mucosa but not in mesenteric adipose tissue is associated with inflammation in Crohn's disease patients

Chronic/abnormal activation of endoplasmic reticulum (ER) stress is linked to the exacerbation of the inflammatory process and has been recently linked to Crohn’s disease (CD) pathophysiology. We investigated the intestinal mucosa and the mesenteric adipose tissue (MAT) collected from CD patients with active disease (CD group) and from non-IBD patients (CTR group) to study ER stress activation and to address tissue-specific modulation in CD. The intestinal mucosa of CD patients showed an upregulation in the expression of ER stress related genes, including ATF3, DNAJC3, STC2, DDIT3, CALR, HSPA5 and HSP90B1. Results showed that EIF2AK3 gene was upregulated, along with increased protein expression of p-eIF2α and p-eIF2α/eIF2α ratio. Additionally, ERN1 gene expression was upregulated, along with an increased spliced/activated form sXBP1 protein. Despite the upregulation of ATF6 gene expression in the intestinal mucosa of CD patients, no differences were found in ATF6 protein expression. Lastly, the analysis of MAT revealed unchanged levels of ER stress markers along with no differences in the activation of UPR. However, chaperone gene expression was modulated in the MAT of CD patients. To conclude, our results address tissue-specific differences in UPR activation in CD and point the ER stress as an important pro-inflammatory mechanism in CD, specifically in the intestinal mucosa.

Stanniocalcin 2 (STC2) expression promotes post-radiation survival, migration and invasion of nasopharyngeal carcinoma cells

Background: Stanniocalcin 2 (STC2) expression is upregulated under multiple stress conditions including hypoxia, nutrient starvation and radiation. Overexpression of STC2 correlates with tumor progression and poor prognosis.

Purpose: We previously demonstrated that overexpression of STC2 in nasopharyngeal carcinomas (NPC) positively correlates with radiation resistance and tumor metastasis, two major clinical obstacles to the improvement of NPC management. However, it remains elusive whether STC2 expression is a critical contributing factor for post-radiation survival and metastasis of NPC cells.

Materials and methods: Using the radiation resistant CNE2 cell line as a model, we examined the importance of STC2 expression for post-radiation survival, migration and invasion. Here, we report the establishment of STC2 knockout lines (CNE2-STC2-KO) using the CRISPR/Cas9-based genome editing technique.

Results: Compared with the parental line, STC2-KO cells showed similar proliferation and morphology in normal culture conditions, and loss of STC2 did not compromise the cell tumorigenicity in nude mice model. However, STC2-KO lines demonstrated increased sensitivity to X-radiation under either normoxic or hypoxic conditions. Particularly, upon X-radiation, parental CNE2 cells only slightly whereas STC2-KO cells remarkably decreased the migration and invasion ability. Cell cycle analysis revealed that loss of STC2 accumulated cells in G₁ and G₂/M phases but decreased S-population.

Conclusion: These data indicate that the expression of STC2, which can be stimulated by metabolic or therapeutic stresses, is one important factor to promote survival and metastasis of post-radiation NPC cells. Therefore, targeting STC2 or relative downstream pathways may provide novel strategies to overcome radiation resistance and metastasis of NPC.

Porcine Fetal-Derived Fibroblasts Alter Gene Expression and Mitochondria to Compensate for Hypoxic Stress During Culture

The Warburg effect is characterized by decreased mitochondrial oxidative phosphorylation and increased glycolytic flux in adequate oxygen. The preimplantation embryo has been described to have characteristics of the Warburg effect, including similar changes in gene expression and mitochondria, which are more rudimentary in appearance. We hypothesized hypoxia would facilitate anaerobic glycolysis in fibroblasts thereby promoting gene expression and media metabolite production reflecting the Warburg effect hallmarks in early embryos. Additionally, we speculated that hypoxia would induce a rudimentary small mitochondrial phenotype observed in several cell types evidenced to demonstrate the Warburg effect. While many have examined the role hypoxia plays in pathological conditions, few studies have investigated changes in primary cells which could be used in somatic cell nuclear transfer. We found that cells grown in 1.25% O₂ had normal cell viability and more, but smaller mitochondria. Several hypoxia-inducible genes were identified, including seven genes for glycolytic enzymes. In conditioned media from hypoxic cells, the quantities of gluconolactone, cytosine, and uric acid were decreased indicating higher consumption than control cells. These results indicate that fibroblasts alter gene expression and mitochondria to compensate for hypoxic stress and maintain viability. Furthermore, the metabolic changes observed, making them more similar to preimplantation embryos, could be facilitating nuclear reprogramming making these cells more amendable to future use in somatic cell nuclear transfer.

Effects of stanniocalcin hormones on rat brown adipose tissue metabolism under fed and fasted conditions

In this study we determined the effect of fed and fasting (48 h) states on the expression of stanniocalcin-1 (Stc1) and stanniocalcin-2 (Stc2) in rat brown adipose tissue (BAT), as well as the in vitro effects of human stanniocalcin 1 and 2 (hSTC-1 and hSTC-2) hormones on lipid and glucose metabolism. In addition, lactate, glycogen levels and hexokinase (HK) activity were determined. In fasting Stc2 expression increased markedly. The targets of action of hSTC-1 and hSTC-2 were glucose uptake and oxidation as well as glycogen storage, controlling the energetic metabolism in BAT. The reduction in glycogen concentration induced by hSTC-2 in fed state might have deleterious consequences in BAT, such as decreased thermogenic activity, FA esterification and other adipocyte functions. On the other hand, the increase of glucose uptake caused by hSTC-1 of fed rats could play a role as a plasma glucose-clearing hormone in the postprandial period.

Pharmacogenomics study of thiazide diuretics and QT interval in multi-ethnic populations: the cohorts for heart and aging research in genomic epidemiology

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.

Stanniocalcin 2 Regulates Non-capacitative Ca2+ Entry and Aggregation in Mouse Platelets

Stanniocalcin 2 (STC2) is a fish protein that controls body Ca²⁺ and phosphate metabolism. STC2 has also been described in mammals, and as platelet function highly depends on both extracellular and intracellular Ca²⁺, we have explored its expression and function in these cells. STC2^−/− mice exhibit shorter tail bleeding time than WT mice. Platelets from STC2-deficient mice showed enhanced aggregation, as well as enhanced Ca²⁺ mobilization in response to the physiological agonist thrombin (Thr) and the diacylglycerol analog, OAG, a selective activator of the non-capacitative Ca²⁺ entry channels. Interestingly, platelets from STC2^−/− mice exhibit attenuated interaction between STIM1 and Orai1 in response to Thr, thus suggesting that STC2 is required for Thr-evoked STIM1-Orai1 interaction and the subsequent store-operated Ca²⁺ entry (SOCE). We have further assessed possible changes in the expression of the most relevant channels involved in non-capacitative Ca²⁺ entry in platelets. Then, protein expression of Orai3, TRPC3 and TRPC6 were evaluated by Western blotting, and the results revealed that while the expression of Orai3 was enhanced in the STC2-deficient mice, others like TRPC3 and TRPC6 remains almost unaltered. Summarizing, our results provide for the first time evidence for a role of STC2 in platelet physiology through the regulation of agonist-induced Ca²⁺ entry, which might be mediated by the regulation of Orai3 channel expression.

Involvement of stanniocalcins in the deregulation of glycaemia in obese mice and type 2 diabetic patients

Stanniocalcins are expressed in the pancreas tissue, and it was suggested a direct correlation between circulating insulin and STC2 concentrations in human. Here, we show a significant correlation between STC1 and both glycaemia and glycosylated haemoglobin among DM2 patients, while DM2 patients who present the greatest glycosylated haemoglobin values exhibited the lowest STC2 expression. However, treatment of patients with antiglycaemic drugs does not significantly modify the expression of both STCs. On the other hand, STC2^‐/‐ mice that exhibited neonatal and adult overweight further presented deregulated glycaemia when they were feed with a hypercaloric diet (breeding pellet, BP). This alteration is more evident at the early stages of the animal life. Deregulated glycaemia in these mice was confirmed using glucose oral test. In addition, STC2^‐/‐ mice present enhanced pancreas size; thus, the histological analysis reveals that WT mice respond to BP diet by increasing the size of the pancreatic islets through inducing cell division, and STC2^‐/‐ mice lack this compensatory mechanism. Contrary, BP fed STC2^‐/‐ mice show enhanced number of islets but of similar size than those fed with regular pellet. Histopathological analysis demonstrates tissue structure disruption and erythrocytes infiltrations in STC2^‐/‐ mice, possibly due to the stress evoked by the BP diet. Finally, enhanced glucagon immunostaining was observed in the islet of STC2^‐/‐ mice, and the glucagon ELISA assay confirmed the increase in the circulating glucagon. Summarizing, we present evidence of the role of STCs, mainly STC2, as a possible early marker during development of diabetes mellitus.

Stanniocalcin2 acts as an anorectic factor through activation of STAT3 pathway

The regulation of food intake and body weight has been hotly investigated. In the present study, we show that stanniocalcin2 (STC2), a cytokine ubiquitously expressed and especially upregulated in many types of human cancers, has a regulatory role in food intake and weight loss. Systemic treatment of C57BL/6 mice with recombinant STC2 protein resulted in decreased food intake and body weight, whereas energy expenditure was not affected. Similarly, STC2 treatment also induced anorexia in hyperphagic leptin-deficient mice, leading to a significant reduction in body weight and improvement of blood glucose levels. Furthermore, intracerebroventricular administration of STC2 to mice led to an acute decrease in food intake, which was mediated, at least in part, by activation of STAT3 pathway. Taken together, our results revealed the importance of STC2 in the regulation of feeding behavior as well as body weight.

Identification of Ran-binding protein M as a stanniocalcin 2 interacting protein and implications for androgen receptor activity

Stanniocalcin (STC), a glycoprotein hormone originally discovered in fish, has been implicated in calcium and phosphate homeostasis. While fishes and mammals possess two STC homologs (STC1 and STC2), the physiological roles of STC2 are largely unknown compared with those of STC1. In this study, we identified Ran-binding protein M (RanBPM) as a novel binding partner of STC2 using yeast two-hybrid screening. The interaction between STC2 and RanBPM was confirmed in mammalian cells by immunoprecipitation. STC2 enhanced the RanBPM-mediated transactivation of liganded androgen receptor (AR), but not thyroid receptor β, glucocorticoid receptor, or estrogen receptor β. We also found that AR interacted with RanBPM in both the absence and presence of testosterone (T). Furthermore, we discovered that STC2 recruits RanBPM/AR complex in T-dependent manner. Taken together, our findings suggest that STC2 is a novel RanBPM-interacting protein that promotes AR transactivation.

Characterization of stanniocalcin 1 binding and signaling in gill cells of Japanese eels

Stanniocalcin 1 (STC1) is a hypocalcemic hormone that is known to play an important role in calcium metabolism in teleost fish. An increase in blood Ca(2) (+) levels stimulates its synthesis and release. The biological action of STC1 inhibits gill Ca(2) (+) transport (GCAT), but we as yet have no clear understanding of how STC1 inhibits GCAT. In the present study, we characterized the binding, signaling, and action of STC1 on gill cells. Treatment of gill cell cultures with the extracts of corpuscles of Stannius or recombinant STC1 proteins (STC1-V5) led to an increase in cytosolic cAMP levels. Using in situ ligand-binding assays, we demonstrated that STC1-V5 binds to both lamellar and inter-lamellar regions of gill sections. The binding sites were significantly increased in gill sections obtained from fish adapted to high-Ca(2) (+) (2 mM) freshwater (FW) as compared with those from fish adapted to low-Ca(2) (+) (0.2 mM) FW. Receptor-binding assays illustrated specific binding of STC1-alkaline phosphatase to plasma membrane (Kd of 0.36 nM), mitochondria (Kd of 0.41 nM), and nuclear (Kd of 0.71 nM) preparations from gill cells. STC1 binding capacity was significantly greater in the plasma membrane preparations of gills obtained from fish adapted to high-Ca(2) (+) FW. Using isolated pavement cells and mitochondria-rich cells in cAMP assays, we obtained results indicating that both cell types responded to STC1. To illustrate the biological action of STC1, we conducted Ca(2) (+) imaging experiments to demonstrate the effects of STC1 on thapsigargin-induced elevation of cytosolic Ca(2) (+). Our results indicated that STC1 exerted its inhibitory action via a cAMP pathway to lower intracellular Ca(2) (+) levels. Intriguingly, we were able to block the action of STC1 using an inhibitor, NS-398, of cyclooxygenase-2 (COX-2), which is known to stimulate the activity of sarcoplasmic and endoplasmic reticulum Ca(2) (+)-ATPase (SERCA). A follow-up experiment in which gill cells were incubated with STC1 revealed a downregulation of the epithelial Ca(2) (+) channel (ecacl) but an upregulation of cox-2 expression. The ECaCl is a gatekeeper for Ca(2) (+) entry, whereas COX-2 mediates an activation of SERCA. Taking these results together, the present study is, to our knowledge, the first to provide evidence of STC1 binding and signaling as well as the first to decipher the mechanism of the effect of STC1 on fish gills.

Transcriptomic responses of corpuscle of Stannius gland of Japanese eels (Anguilla japonica) to changes in water salinity

Physiological studies of a unique endocrine gland in fish, named corpuscles of Stannius (CS), described a Ca2(+)-regulatory function for this gland mediated by stanniocalcin-1, a hypocalcemic polypeptide hormone. However, to date, the endocrine functions of the glands have not been completely elucidated.We hypothesized that other unidentified active principles in the glands are involved in the regulation of plasma ion (Na(+), Ca2(+)) and/or blood pressure. In this study, transcriptome sequencing of CS glands was performed using Japanese eels (Anguilla japonica) adapted to freshwater (FW) or seawater (SW) to reveal the presence and differential expression of genes encoding proteins related to the ion-osmoregulatory and pressor functions. We acquired a total of 14.1 Mb and 12.1 Mb quality-trimmed reads from the CS glands collected from FW and SW adapted eels, respectively. The de novo assembly resulted in 9254 annotated genes. Among them, 475 genes were differentially expressed with 357 up- and 118 down-regulated in the SW group. Gene ontology analysis further demonstrated the presence of natriuresis and pressor related genes. In summary, ours is the first study using high-throughput sequencing to identify gene targets that could explain the physiological importance of the CS glands.

Stanniocalicin 2 suppresses breast cancer cell migration and invasion via the PKC/claudin-1-mediated signaling

Stanniocalcin (STC), a glycoprotein hormone, is expressed in a wide variety of tissues to regulate Ca²⁺ and PO4^- homeostasis. STC2, a member of STC family, has been reported to be associated with tumor development. In this study, we investigated whether the expression of STC2 is associated with migration and invasion of breast cancer cells. We found that breast cancer cell line 231 HM transfected with STC2 shRNA displayed high motility, fibroblast morphology, and enhanced cell migration and invasion. Introduction of STC2 in 231 cells reduced cell migration and invasion. In response to irradiation, silencing of STC2 in 231 HM cells reduced apoptosis, whereas overexpression of STC2 in 231 cells promoted apoptosis, compared with in control cells. Mechanistic study showed that STC2 negatively regulated PKC to control the expression of Claudin-1, which subsequently induced the expressions of EMT-related factors including ZEB1, ZO-1, Slug, Twist, and MMP9. Suppression of PKC activity by using a PKC inhibitor (Go 6983) restored the normal motility of STC2-silenced cells. Furthermore, in vivo animal assay showed that STC2 inhibited tumorigenesis and metastasis of breast cancer cells. Collectively, these results indicate that STC2 may inhibit EMT at least partially through the PKC/Claudin-1-mediated signaling in human breast cancer cells. Thus, STC2 may be exploited as a biomarker for metastasis and targeted therapy in human breast cancer.

Aryl hydrocarbon receptor-dependent stanniocalcin 2 induction by cinnabarinic acid provides cytoprotection against endoplasmic reticulum and oxidative stress

The aryl hydrocarbon receptor (AhR) is a cytosolic ligand-activated transcription factor historically known for its role in xenobiotic metabolism. Although AhR activity has previously been shown to play a cytoprotective role against intrinsic apoptotic stimuli, the underlying mechanism by which AhR confers cytoprotection against apoptosis is largely unknown. Here, we demonstrate that activation of AhR by the tryptophan catabolite cinnabarinic acid (CA) directly upregulates expression of stanniocalcin 2 (Stc2) to elicit cytoprotection against apoptosis induced by endoplasmic reticulum stress and oxidative stress. Chromatin immunoprecipitation studies demonstrated that CA treatment induces direct AhR binding to a region of the Stc2 promoter containing multiple xenobiotic response elements. Using isolated primary hepatocytes from AhR wild-type (AhR floxed) and liver-specific AhR conditional knockout mice, we showed that pretreatment with CA conferred cytoprotection against hydrogen peroxide (H(2)O(2))-, thapsigargin-, and ethanol-induced apoptosis in an AhR-dependent manner. Furthermore, suppressing Stc2 expression using RNA interference confirmed that the cytoprotective properties of CA against H(2)O(2), thapsigargin, and ethanol injury were absolutely dependent on Stc2. Immunochemistry revealed the presence of Stc2 in the endoplasmic reticulum and on the cell surface, consistent with Stc2 secretion and autocrine and/or paracrine signaling. Finally, in vivo data using a mouse model of acute alcohol hepatotoxicity demonstrated that CA provided cytoprotection against ethanol-induced apoptosis, hepatic microvesicular steatosis, and liver injury. Collectively, our data uncovered a novel mechanism for AhR-mediated cytoprotection in the liver that is dependent on CA-induced Stc2 activity.

Transgenerational effects of binge drinking in a primate model: implications for human health

OBJECTIVE

To determine if binge ethanol consumption before ovulation affects oocyte quality, gene expression, and subsequent embryo development.

DESIGN

Binge levels of ethanol were given twice weekly for 6 months, followed by a standard in vitro fertilization cycle and subsequent natural mating.

SETTING

National primate research center.

ANIMAL(S)

Adult female rhesus monkeys.

INTERVENTION(S)

Binge levels of ethanol, given twice weekly for 6 months before a standard in vitro fertilization cycle with or without embryo culture. With in vivo development, ethanol treatment continued until pregnancy was identified.

MAIN OUTCOME MEASURE(S)

Oocyte and cumulus/granulosa cell gene expression, embryo development to blastocyst, and pregnancy rate.

RESULT(S)

Embryo development in vitro was reduced; changes were found in oocyte and cumulus cell gene expression; and spontaneous abortion during very early gestation increased.

CONCLUSION(S)

This study provides evidence that binge drinking can affect the developmental potential of oocytes even after alcohol consumption has ceased.

Activation of gill Ca2+-sensing receptor as a protective pathway to reduce Ca2+-induced cytotoxicity

The expression of the Ca(2) (+)-sensing receptor (Casr) in the endocrine gland known as the corpuscle of Stannius (CS) regulates the secretion of the hypocalcemic hormone stanniocalcin-1 (STC1) to inhibit gill Ca(2) (+) uptake. Although numerous studies have reported the branchial expression of Casr and Stc1, the functions of these proteins in gills have not been elucidated yet. On the basis of recent findings regarding the autocrine/paracrine functions of STC1 in mammalian models, we proposed the hypothesis that branchial CaSR has an in situ 'sensing' function to regulate STC1 that maintains local Ca(2) (+) homeostasis. In this study, we investigated Casr-mediated signaling and its regulation of Stc1 and cyclooxygenase-2 (Cox2) expression/function using a primary gill-cell culture model. The biochemical responses of gill cells isolated from Japanese eels to an increasing concentration of extracellular Ca(2) (+) (0.1-1 mM) were tested. This stimulation led to a transient increase in phosphatidylcholine-phospholipase C (PC-PLC) activity, followed by activation of ERK and inositol 1,4,5-trisphosphate-Ca(2) (+)/calmodulin-dependent protein kinase 2 (CaMK2) signaling pathways. Cotreatment with the calcimimetic R467 caused synergistic effects on Ca(2) (+)-stimulated PC-PLC activity, ERK signaling, and CaMK2 signaling. The activation of the CaSR-PLC-ERK pathway was associated with increased expression levels of Stc1 and Cox2 as confirmed by the inhibition of Erk using a chemical inhibitor, PD98059. Functionally, Ca(2) (+)/R-467 pretreatment was found to protect cells from thapsigargin-induced cell death. Inhibition of COX2 activity using NS398 abolished this protection, while transduction of STC1 lentiviral particles in the gill cells increased the protective effects. Collectively, our data revealed the expression of functional CaSR in gill tissues. The identification of the CaSR-STC1/COX2-mediated protective pathway in gill cells sheds light on a possible cellular protective mechanism against an increase in intracellular Ca(2) (+) levels associated with transepithelial Ca(2) (+) transport.

Expression of stanniocalcin-1 and stanniocalcin-2 in laryngeal squamous cell carcinoma and correlations with clinical and pathological parameters

Background

Stanniocalcin-1 (STC1) and stanniocalcin-2 (STC2) are secreted glycoprotein hormones involved in various types of human malignancies. The roles of STC1 and STC2 in laryngeal squamous cell carcinoma (LSCC) remain unknown. We investigated correlations between STC1 and STC2 expression and clinicopathological or prognostic factors in LSCC.

Methods

Pre-surgical peripheral blood samples were collected between 2012 and 2013 from 62 patients with LSCC. Quantitative RT-PCR analysis was performed to examine mRNA levels of STC1 and STC2. Immunohistochemistry was performed to retrospectively analyze 90 paraffin-embedded LSCC tissue samples, which were obtained from patients who received surgery between 2006 and 2009. These patients did not have histories of treatment or malignancies. Univariate analysis of patient survival was performed by the Kaplan–Meier method. Multivariate analyses were performed with the Cox proportional hazards model.

Results

The relative mRNA levels of STC1 and STC2 in peripheral blood were significantly greater in LSCC patients than those of healthy volunteers (both P<0.05). STC2 protein expression in tumor tissues was associated with invasion into the thyroid cartilage, T-Stage, lymphatic metastasis, clinical stage, and pathological differentiation (all P<0.05). In addition, STC2 protein expression was an independent prognostic factor for overall survival in patients with LSCC (P = 0.025). In contrast, STC1 expression only correlated with clinical stage (P = 0.026) and was not an independent or significant prognostic factor.

Conclusions

Circulating STC1 and STC2 mRNA are potentially useful blood markers for LSCC. Our results strongly suggest that the STC2 protein, but not STC1, may be a valuable biomarker for LSCC malignancies and a prognostic marker for poor outcome following surgery. Future studies should examine STC2 as a novel molecular target for the treatment of LSCC.

Stromal interaction molecule 1 is essential for normal cardiac homeostasis through modulation of ER and mitochondrial function

The endoplasmic reticulum (ER) Ca(2+) sensor stromal interaction molecule 1 (STIM1) has been implicated as a key mediator of store-dependent and store-independent Ca(2+) entry pathways and maintenance of ER structure. STIM1 is present in embryonic, neonatal, and adult cardiomyocytes and has been strongly implicated in hypertrophic signaling; however, the physiological role of STIM1 in the adult heart remains unknown. We, therefore, developed a novel cardiomyocyte-restricted STIM1 knockout ((cr)STIM1-KO) mouse. In cardiomyocytes isolated from (cr)STIM1-KO mice, STIM1 expression was reduced by ∼92% with no change in the expression of related store-operated Ca(2+) entry proteins, STIM2, and Orai1. Immunoblot analyses revealed that (cr)STIM1-KO hearts exhibited increased ER stress from 12 wk, as indicated by increased levels of the transcription factor C/EBP homologous protein (CHOP), one of the terminal markers of ER stress. Transmission electron microscopy revealed ER dilatation, mitochondrial disorganization, and increased numbers of smaller mitochondria in (cr)STIM1-KO hearts, which was associated with increased mitochondrial fission. Using serial echocardiography and histological analyses, we observed a progressive decline in cardiac function in (cr)STIM1-KO mice, starting at 20 wk of age, which was associated with marked left ventricular dilatation by 36 wk. In addition, we observed the presence of an inflammatory infiltrate and evidence of cardiac fibrosis from 20 wk in (cr)STIM1-KO mice, which progressively worsened by 36 wk. These data demonstrate for the first time that STIM1 plays an essential role in normal cardiac function in the adult heart, which may be important for the regulation of ER and mitochondrial function.

Molecular regulation of the pore component of CRAC channels, Orai1

Store-operated Ca(2+) entry (SOCE) is a fundamental mechanism ubiquitously employed by cells to elevate intracellular Ca(2+) concentrations ([Ca(2+)]i). Increased intracellular Ca(2+) ions act as a second messenger that can stimulate a variety of downstream signaling pathways affecting proliferation, secretion, differentiation, and death of cells. In immune cells, immune receptor stimulation induces endoplasmic reticulum Ca(2+) store depletion that subsequently activates Ca(2+)-release-activated-Ca(2+) (CRAC) channels, a prototype of store-operated Ca(2+) (SOC) channels. Identification of Orai1 as the pore subunit of CRAC channels has provided the much-needed molecular tool to dissect the mechanism of activation and regulation of these channels. In this review, we discuss the recent advances in understanding the regulatory mechanisms and posttranslational modifications that regulate diverse aspects of CRAC channel function.

STIM1/Orai1-mediated SOCE: current perspectives and potential roles in cardiac function and pathology

Store-operated Ca²⁺ entry (SOCE) is critical for Ca²⁺ signaling in nonexcitable cells; however, its role in the regulation of cardiomyocyte Ca²⁺ homeostasis has only recently been investigated. The increased understanding of the role of stromal interaction molecule 1 (STIM1) in regulating SOCE combined with recent studies demonstrating the presence of STIM1 in cardiomyocytes provides support that this pathway co-exists in the heart with the more widely recognized Ca²⁺ handling pathways associated with excitation-contraction coupling. There is now substantial evidence that STIM1-mediated SOCE plays a key role in mediating cardiomyocyte hypertrophy, both in vitro and in vivo, and there is growing support for the contribution of SOCE to Ca²⁺ overload associated with ischemia/reperfusion injury. Here, we provide an overview of our current understanding of the molecular regulation of SOCE and discuss the evidence supporting the role of STIM1/Orai1-mediated SOCE in regulating cardiomyocyte function.

Ca2+ influx through store-operated Ca2+ channels reduces Alzheimer disease β-amyloid peptide secretion

Alzheimer disease (AD), the leading cause of dementia, is characterized by the accumulation of β-amyloid peptides (Aβ) in senile plaques in the brains of affected patients. Many cellular mechanisms are thought to play important roles in the development and progression of AD. Several lines of evidence point to the dysregulation of Ca(2+) homeostasis as underlying aspects of AD pathogenesis. Moreover, direct roles in the regulation of Ca(2+) homeostasis have been demonstrated for proteins encoded by familial AD-linked genes such as PSEN1, PSEN2, and APP, as well as Aβ peptides. Whereas these studies support the hypothesis that disruption of Ca(2+) homeostasis contributes to AD, it is difficult to disentangle the effects of familial AD-linked genes on Aβ production from their effects on Ca(2+) homeostasis. Here, we developed a system in which cellular Ca(2+) homeostasis could be directly manipulated to study the effects on amyloid precursor protein metabolism and Aβ production. We overexpressed stromal interaction molecule 1 (STIM1) and Orai1, the components of the store-operated Ca(2+) entry pathway, to generate cells with constitutive and store depletion-induced Ca(2+) entry. We found striking effects of Ca(2+) entry induced by overexpression of the constitutively active STIM1(D76A) mutant on amyloid precursor protein metabolism. Specifically, constitutive activation of Ca(2+) entry by expression of STIM1(D76A) significantly reduced Aβ secretion. Our results suggest that disruptions in Ca(2+) homeostasis may influence AD pathogenesis directly through the modulation of Aβ production.

Regulation of CRAC channels by protein interactions and post-translational modification

Store-operated Ca(2+) entry (SOCE) is a widespread mechanism to elevate the intracellular Ca(2+) concentrations and stimulate downstream signaling pathways affecting proliferation, secretion, differentiation and death in different cell types. In immune cells, immune receptor stimulation induces intracellular Ca(2+) store depletion that subsequently activates Ca(2+)-release-activated-Ca(2+) (CRAC) channels, a prototype of store-operated Ca(2+) (SOC) channels. CRAC channel opening leads to activation of diverse downstream signaling pathways affecting proliferation, differentiation, cytokine production and cell death. Recent identification of STIM1 as the endoplasmic reticulum Ca(2+) sensor and Orai1 as the pore subunit of CRAC channels has provided the much-needed molecular tools to dissect the mechanism of activation and regulation of CRAC channels. In this review, we discuss the recent advances in understanding the associating partners and posttranslational modifications of Orai1 and STIM1 proteins that regulate diverse aspects of CRAC channel function.