Nickel-catalyzed regio- and enantio-selective Markovnikov hydromonofluoroalkylation of 1,3-dienes.

A highly enantio- and regio-selective Markovnikov hydromonofluoro(methyl)alkylation of 1,3-dienes was developed using redox-neutral nickel catalysis. It provided a facile strategy to construct diverse monofluoromethyl- or monofluoroalkyl-containing chiral allylic molecules. Notably, this represents the first catalytic asymmetric Markovnikov hydrofluoroalkylation of olefins. The practicability of this methodology is further highlighted by its broad substrate scope, mild base-free conditions, excellent enantio- and regio-selectivity, and diversified product elaborations to access useful fluorinated building blocks.

Curcumin and NCLX inhibitors share anti-tumoral mechanisms in microsatellite-instability-driven colorectal cancer.

BACKGROUND AND AIMS: Recent evidences highlight a role of the mitochondria calcium homeostasis in the development of colorectal cancer (CRC). To overcome treatment resistance, we aimed to evaluate the role of the mitochondrial sodium-calcium-lithium exchanger (NCLX) and its targeting in CRC. We also identified curcumin as a new inhibitor of NCLX. METHODS: We examined whether curcumin and pharmacological compounds induced the inhibition of NCLX-mediated mitochondrial calcium (mtCa2+) extrusion, the role of redox metabolism in this process. We evaluated their anti-tumorigenic activity in vitro and in a xenograft mouse model. We analyzed NCLX expression and associations with survival in The Cancer Genome Atlas (TCGA) dataset and in tissue microarrays from 381 patients with microsatellite instability (MSI)-driven CRC. RESULTS: In vitro, curcumin exerted strong anti-tumoral activity through its action on NCLX with mtCa2+ and reactive oxygen species overload associated with a mitochondrial membrane depolarization, leading to reduced ATP production and apoptosis. NCLX inhibition with pharmacological and molecular approaches reproduced the effects of curcumin. NCLX inhibitors decreased CRC tumor growth in vivo. Both transcriptomic analysis of TCGA dataset and immunohistochemical analysis of tissue microarrays demonstrated that higher NCLX expression was associated with MSI status, and for the first time, NCLX expression was significantly associated with recurrence-free survival. CONCLUSIONS: Our findings highlight a novel anti-tumoral mechanism of curcumin through its action on NCLX and mitochondria calcium overload that could benefit for therapeutic schedule of patients with MSI CRC.

MicroRNA-221 promotes tumor progression by targeting HHIP in human glioblastoma.

BACKGROUND: MicroRNAs are found to be aberrantly expressed in multiple cancers, including glioblastoma (GBM), and microRNA-221 (miR-221) has been verified as an oncogene in various human cancers. Nevertheless, the role of miR-221 in GBM is unclear. This study aimed to investigate the miR-221 expression level in GBM and to evaluate its function and underlying mechanisms. METHODS: Western blotting and qPCR were used to determine the expression of human hedgehog-interacting protein (HHIP) and miR-221 levels. MiR-221-inhibited cell models were constructed, and siRNA was used for HHIP silencing. Cell proliferation was analyzed by MTT and colony formation assays and a subcutaneous xenograft model. Cell migration and invasion was analyzed by wound healing and Transwell invasion assays. A dual luciferase reporter assay system was used to clarify the relationship between miR-221 and HHIP. RESULTS: The results of this study revealed that miR-221 expression was upregulated in GBM tissues and A172, U251, as well as T98G cells, as detected by real-time PCR analysis. MTT, Transwell, and colony formation assays revealed that miR-221 knockdown could suppress GBM cells from proliferating, migrating, and invading in vitro. Moreover, animal experiments showed that tumor growth in vivo was inhibited when miR-221 expression decreased. Furthermore, HHIP was predicted and verified to be a target of miR-221 by bioinformatics analysis, and luciferase and western blot assays. In addition, HHIP silencing rescued the suppressive effect of a miR-221 inhibitor on the proliferation, migration, and invasion of GBM cells. CONCLUSIONS: Our results indicated that miR-221 is upregulated in GBM and enhances tumor progression by targeting HHIP, which suggests this may be a potential therapeutic target for GBM.

Dichotomous role of the human mitochondrial Na+/Ca2+/Li+ exchanger NCLX in colorectal cancer growth and metastasis.

Despite the established role of mitochondria in cancer, the mechanisms by which mitochondrial Ca2+ (mtCa2+) regulates tumorigenesis remain incompletely understood. The crucial role of mtCa2+ in tumorigenesis is highlighted by altered expression of proteins mediating mtCa2+ uptake and extrusion in cancer. Here, we demonstrate decreased expression of the mitochondrial Na+/Ca2+/Li+ exchanger NCLX (SLC8B1) in human colorectal tumors and its association with advanced-stage disease in patients. Downregulation of NCLX causes mtCa2+ overload, mitochondrial depolarization, decreased expression of cell-cycle genes and reduced tumor size in xenograft and spontaneous colorectal cancer mouse models. Concomitantly, NCLX downregulation drives metastatic spread, chemoresistance, and expression of epithelial-to-mesenchymal, hypoxia, and stem cell pathways. Mechanistically, mtCa2+ overload leads to increased mitochondrial reactive oxygen species, which activate HIF1α signaling supporting metastasis of NCLX-null tumor cells. Thus, loss of NCLX is a novel driver of metastasis, indicating that regulation of mtCa2+ is a novel therapeutic approach in metastatic colorectal cancer.

Colorectal cancer is the second largest cause of cancer deaths worldwide. Even in cases where the cancer is diagnosed and treated early, cells can sometimes survive treatment and spread to other organs. Once the cancer has spread, the survival rate is less than 15%. Mitochondria are compartments in the cell that produce energy, and they play an important role in supporting the rapid growth of cancer cells. The levels of calcium ions in mitochondria control how they produce energy, a process that is altered in cancer cells. To better understand how calcium ions influence colorectal cancer growth, Pathak, Gueguinou et al. studied a protein called NCLX, which controls calcium levels by pumping them out of the mitochondria. Two mouse strains that were used to study what happens if NCLX is missing. The first strain was genetically modified to disable the gene for NCLX and then exposed to carcinogens. The second strain was injected with colorectal cancer cells from a human tumor that were lacking NCLX. In both strains, the tumors that formed were smaller than in mice with NCLX. However, the human cancer cells in the second model were more likely to spread to other organs. This is likely because the build-up of calcium ions in the mitochondria of mice lacking NCLX led to an increase in the production of hypoxia-inducible factor-1a, a protein that is a common driver of cancer spread. Pathak, Gueguinou et al. demonstrated how NCLX can affect colorectal cancer progression. It suggests that it may have opposing effects during early and late-stage colorectal cancer, encouraging tumor growth but also decreasing the spread to other organs. Further research could help refine treatments at different stages of the disease.

Redox and mTOR-dependent regulation of plasma lamellar calcium influx controls the senescence-associated secretory phenotype.

IMPACT STATEMENT: Through its ability to evoke responses from cells in a paracrine fashion, the senescence-associated secretory phenotype (SASP) has been linked to numerous age-associated disease pathologies including tumor invasion, cardiovascular dysfunction, neuroinflammation, osteoarthritis, and renal disease. Strategies which limit the amplitude and duration of SASP serve to delay age-related degenerative decline. Here we demonstrate that the SASP regulation is linked to shifts in intracellular Ca2+ homeostasis and strategies which rescue redox-dependent calcium entry including enzymatic H2O2 scavenging, TRP modulation, or mTOR inhibition block SASP and TRPC6 gene expression. As Ca2+ is indispensable for secretion from both secretory and non-secretory cells, it is exciting to speculate that the expression of plasma lamellar TRP channels critical for the maintenance of intracellular Ca2+ homeostasis may be coordinately regulated with the SASP.

L-type Ca2+ channel blockers promote vascular remodeling through activation of STIM proteins.

Voltage-gated L-type Ca2+ channel (Cav1.2) blockers (LCCBs) are major drugs for treating hypertension, the preeminent risk factor for heart failure. Vascular smooth muscle cell (VSMC) remodeling is a pathological hallmark of chronic hypertension. VSMC remodeling is characterized by molecular rewiring of the cellular Ca2+ signaling machinery, including down-regulation of Cav1.2 channels and up-regulation of the endoplasmic reticulum (ER) stromal-interacting molecule (STIM) Ca2+ sensor proteins and the plasma membrane ORAI Ca2+ channels. STIM/ORAI proteins mediate store-operated Ca2+ entry (SOCE) and drive fibro-proliferative gene programs during cardiovascular remodeling. SOCE is activated by agonists that induce depletion of ER Ca2+, causing STIM to activate ORAI. Here, we show that the three major classes of LCCBs activate STIM/ORAI-mediated Ca2+ entry in VSMCs. LCCBs act on the STIM N terminus to cause STIM relocalization to junctions and subsequent ORAI activation in a Cav1.2-independent and store depletion-independent manner. LCCB-induced promotion of VSMC remodeling requires STIM1, which is up-regulated in VSMCs from hypertensive rats. Epidemiology showed that LCCBs are more associated with heart failure than other antihypertensive drugs in patients. Our findings unravel a mechanism of LCCBs action on Ca2+ signaling and demonstrate that LCCBs promote vascular remodeling through STIM-mediated activation of ORAI. Our data indicate caution against the use of LCCBs in elderly patients or patients with advanced hypertension and/or onset of cardiovascular remodeling, where levels of STIM and ORAI are elevated.

Deficiency of platelet adhesion molecule CD226 causes megakaryocyte development and platelet hyperactivity.

This study used constitutive CD226 gene knockout (KO) mice as a model to investigate the functions and mechanisms of CD226 in megakaryocyte (MK) maturation and platelet activation. Although CD226 deficiency did not cause MK polyploidization or platelet granule abnormalities, increased MK counts were detected in the femora bone marrow (BM) and spleen of CD226 KO mice. Particularly, CD226 KO mice have a more extensive membrane system in MKs and platelets than wild-type (WT) mice. We also demonstrated that CD226 KO mice displayed increased platelet counts, shortened bleeding time, and enhanced platelet aggregation. CD226 KO platelets had an increased mature platelet ratio compared to the control platelets. In addition, the observed reduction in bleeding time may be due to decreased nitric oxide (NO) production in the platelets. Platelet-specific CD226-deficient mice showed similar increased MK counts, shortened bleeding time, enhanced platelet aggregation, and decreased NO production in platelets. Furthermore, we performed middle cerebral artery occlusion-reperfusion surgery on WT and CD226 KO mice to explore the potential effect of CD226 on acute ischemia-reperfusion injury; the results revealed that CD226 deficiency led to significantly increased infarct area. Thus, CD226 is a promising candidate for the treatment of thrombotic disorders.

A new selective pharmacological enhancer of the Orai1 Ca2+ channel reveals roles for Orai1 in smooth and skeletal muscle functions.

Store operated calcium (Ca2+) entry is an important homeostatic mechanism in cells, whereby the release of Ca2+ from intracellular endoplasmic reticulum stores triggers the activation of a Ca2+ influx pathway. Mediated by Orai1, this Ca2+ influx has specific and essential roles in biological processes as diverse as lactation to immunity. Although pharmacological inhibitors of this Ca2+ influx mechanism have helped to define the role of store operated Ca2+ entry in many cellular events, the lack of isoform specific modulators and activators of Orai1 has limited our full understanding of these processes. Here we report the identification and synthesis of an Orai1 activity enhancer that concurrently potentiated Orai1 Ca2+ -dependent inactivation (CDI). This unique enhancer of Orai1 had only a modest effect on Orai3 with weak inhibitory effects at high concentrations in intact MCF-7 breast cancer cells. The Orai1 enhancer heightened vascular smooth muscle cell migration induced by platelet-derived growth factor and the unique store operated Ca2+ entry pathway present in skeletal muscle cells. These studies show that IA65 is an exemplar for the translation and development of Orai isoform selective agents. The ability of IA65 to activate CDI demonstrates that agents can be developed that can enhance Orai1-mediated Ca2+ influx but avoid the cytotoxicity associated with sustained Orai1 activation. IA65 and/or future analogues with similar Orai1 and CDI activating properties could be fine tuners of physiological processes important in specific disease states, such as cellular migration and immune cell function.

CD226 deficiency on regulatory T cells aggravates renal fibrosis via up-regulation of Th2 cytokines through miR-340.

In this study, we observed that deletion of CD226 on regulatory T cells (Tregs) precedes renal fibrosis in a mouse unilateral ureteral obstruction (UUO) model. First, we generated Treg-specific CD226 gene knockout mice (CD226fl/fl Foxp3YFP-Cre ). Next, CD226fl/fl Foxp3YFP-Cre mice and Foxp3YFP-Cre control mice were subjected to UUO surgery. Pathologic analysis and Sirius red and Masson's trichrome staining showed that the kidneys of CD226fl/fl Foxp3YFP-Cre mice following UUO showed much more severe interstitial fibrosis than Foxp3YFP-Cre control mice at days 10 and 20. Additionally, CD226fl/fl Foxp3YFP-Cre mice showed increased fibronectin expression, as demonstrated by immunohistochemistry (IHC) staining. Although Treg cell-restricted CD226 deficiency showed increased Foxp3+ expression, expression of the cell surface functional molecule CD103 was significantly reduced, indicating impaired homeostasis in the Tregs of CD226fl/fl Foxp3YFP-Cre mice. To better understand CD226 function, RNA sequencing (RNA-Seq) analysis was conducted in Tregs isolated from CD226fl/fl Foxp3YFP-Cre and Foxp3YFP-Cre mice. RNA-Seq data showed that the helper T cell (Th) 2-related cytokines IL-4 and IL-10 were significantly up-regulated in CD226 deficient Tregs. In addition, mRNA analysis of kidney samples from the mice following UUO by qPCR also showed increased IL-4 and IL-10 expression in CD226fl/fl Foxp3YFP-Cre mice, as well as elevated TGF-ß1 levels, indicating that CD226 deficiency in Tregs resulted in the acquisition of the ability to produce Th2 cytokines. Finally, we found that microRNA-340 (miR-340), which was down-regulated in Tregs isolated from CD226fl/fl Foxp3YFP-Cre mice, directly regulated IL-4 gene expression in vitro. These data suggest that the promotion of CD226 signaling on Tregs is a therapeutic target for renal disease.

Lipidic synthetic alkaloids as SK3 channel modulators. Synthesis and biological evaluation of 2-substituted tetrahydropyridine derivatives with potential anti-metastatic activity.

Small Conductance Calcium (Ca2+)-activated potassium (K+) channels (SKCa) are now proved to be involved in many cancer cell behaviors such as proliferation or migration. The SK3 channel isoform was particularly described in breast cancer where it can be associated with the Orai1 Ca2+ channel to form a complex that regulates the Ca2+ homeostasis during tumor development and acts as a potent mediator of bone metastases development in vivo. Until now, very few specific blockers of Orai1 and/or SK3 have been developed as potential anti-metastatic compounds. In this study, we illustrated the synthesis of new families of lipophilic pyridine and tetrahydropyridine derivatives designed as potential modulators of SK3 channel. The toxicity of the newly synthesized compounds and their migration effects were evaluated on the breast cancer cell line MDA-MB-435s. Two molecules (7a and 10c) demonstrated a significant decrease in the SK3 channel-dependent migration as well as the SK3/Orai1-related Ca2+ entry. Current measurements showed that these compounds are more likely SK3-selective. Taken all together these results suggest that such molecules could be considered as promising anti-metastatic drugs in breast cancer.

A calcium/cAMP signaling loop at the ORAI1 mouth drives channel inactivation to shape NFAT induction.

ORAI1 constitutes the store-operated Ca2+ release-activated Ca2+ (CRAC) channel crucial for life. Whereas ORAI1 activation by Ca2+-sensing STIM proteins is known, still obscure is how ORAI1 is turned off through Ca2+-dependent inactivation (CDI), protecting against Ca2+ toxicity. Here we identify a spatially-restricted Ca2+/cAMP signaling crosstalk critical for mediating CDI. Binding of Ca2+-activated adenylyl cyclase 8 (AC8) to the N-terminus of ORAI1 positions AC8 near the mouth of ORAI1 for sensing Ca2+. Ca2+ permeating ORAI1 activates AC8 to generate cAMP and activate PKA. PKA, positioned by AKAP79 near ORAI1, phosphorylates serine-34 in ORAI1 pore extension to induce CDI whereas recruitment of the phosphatase calcineurin antagonizes the effect of PKA. Notably, CDI shapes ORAI1 cytosolic Ca2+ signature to determine the isoform and degree of NFAT activation. Thus, we uncover a mechanism of ORAI1 inactivation, and reveal a hitherto unappreciated role for inactivation in shaping cellular Ca2+ signals and NFAT activation.

Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity.

Store-operated Ca2+ entry (SOCE) is a ubiquitous pathway for Ca2+ influx across the plasma membrane (PM). SOCE is mediated by the endoplasmic reticulum (ER)-associated Ca2+-sensing proteins stromal interaction molecule 1 (STIM1) and STIM2, which transition into an active conformation in response to ER Ca2+ store depletion, thereby interacting with and gating PM-associated ORAI1 channels. Although structurally homologous, STIM1 and STIM2 generate distinct Ca2+ signatures in response to varying strengths of agonist stimulation. The physiological functions of these Ca2+ signatures, particularly under native conditions, remain unclear. To investigate the structural properties distinguishing STIM1 and STIM2 activation of ORAI1 channels under native conditions, here we used CRISPR/Cas9 to generate STIM1-/-, STIM2-/-, and STIM1/2-/- knockouts in HEK293 and colorectal HCT116 cells. We show that depending on cell type, STIM2 can significantly sustain SOCE in response to maximal store depletion. Utilizing the SOCE modifier 2-aminoethoxydiphenyl borate (2-APB), we demonstrate that 2-APB-activated store-independent Ca2+ entry is mediated exclusively by endogenous STIM2. Using variants that either stabilize or disrupt intramolecular interactions of STIM C termini, we show that the increased flexibility of the STIM2 C terminus contributes to its selective store-independent activation by 2-APB. However, STIM1 variants with enhanced flexibility in the C terminus failed to support its store-independent activation. STIM1/STIM2 chimeric constructs indicated that coordination between N-terminal sensitivity and C-terminal flexibility is required for specific store-independent STIM2 activation. Our results clarify the structural determinants underlying activation of specific STIM isoforms, insights that are potentially useful for isoform-selective drug targeting.

CD226 is involved in megakaryocyte activation and early-stage differentiation.

This study was conducted to investigate the effect of CD226 on the differentiation, activation, and polyploidization of megakaryocytes (MKs) and explore the potential mechanism. Dami (megakaryocyte line) cell maturation was induced by phorbol 12-myristate 13-acetate. CD226 was silenced by infection with a CD226-specific shRNA lentiviral vector. The mRNA level of CD226 was detected by qRT-PCR. The expressions of Dami cells surface CD226, MK specific markers CD41 and CD62P, and DNA ploidy in Dami cells and CD226 knockdown (KD) cells were evaluated by flow cytometry. The effect of CD226 on the expression of megakaryocyte-associated transcription factors was measured by western blot and confocal analysis. Transfection with CD226 shRNA lentivirus dramatically decreased the level of CD226 and expression of CD62 P in Dami cells. Silencing of CD226 caused morphological changes and differentiation retardation in low-ploidy MK. Furthermore, CD226 knockout (KO) mice exhibited increased 2N-4N low-ploidy MK and decreased ≥8N polyploidy. Interestingly, silencing of CD226 in megakaryocytic cells down-regulated the expression of early stage transcription factors includes GATA-binding factor 1 (GATA-1) and friend leukemia integration 1 (FLI-1), but not late-stage nuclear factor, erythroid 2 (NF-E2). CD226 is involved in MKs activation and polyploidy cell cycle control.

Induction of store-operated calcium entry (SOCE) suppresses glioblastoma growth by inhibiting the Hippo pathway transcriptional coactivators YAP/TAZ.

Glioblastomas (GBM) are the most aggressive brain cancers without effective therapeutics. The Hippo pathway transcriptional coactivators YAP/TAZ were implicated as drivers in GBM progression and could be therapeutic targets. Here we found in an unbiased screen of 1650 compounds that amlodipine is able to inhibit survival of GBM cells by suppressing YAP/TAZ activities. Instead of its known function as an L-type calcium channel blocker, we found that amlodipine is able to activate Ca2+ entry by enhancing store-operated Ca2+ entry (SOCE). Amlodipine as well as approaches that cause store depletion and activate SOCE trigger phosphorylation and activation of Lats1/2, which in turn phosphorylate YAP/TAZ and prevent their accumulation in the cell nucleus. Furthermore, we identified that protein kinase C (PKC) beta II is a major mediator of Ca2+-induced Lats1/2 activation. Ca2+ induces accumulation of PKC beta II in an actin cytoskeletal compartment. Such translocation depends on inverted formin-2 (INF2). Depletion of INF2 disrupts both PKC beta II translocation and Lats1/2 activation. Functionally, we found that elevation of cytosolic Ca2+ or PKC beta II expression inhibits YAP/TAZ-mediated gene transcription. In vivo PKC beta II expression inhibits GBM tumor growth and prolongs mouse survival through inhibition of YAP/TAZ in an orthotopic mouse xenograft model. Our studies indicate that Ca2+ is a crucial intracellular cue that regulates the Hippo pathway and that triggering SOCE could be a strategy to target YAP/TAZ in GBM.

Delayed cognitive deficits can be alleviated by calcium antagonist nimodipine by downregulation of apoptosis following whole brain radiotherapy.

Radiation therapy is important for the comprehensive treatment of intracranial tumors. However, the molecular mechanisms underlying the pathogenesis of delayed cognitive dysfunction are not well-defined and effective treatments or prevention measures remain insufficient. In the present study, 60 adult male Wistar rats were randomly divided into three groups, which included a control, whole brain radiotherapy (WBRT) (single dose of 30 Gy of WBRT) and nimodipine (single dose of 30 Gy of WBRT followed by nimodipine injection intraperitoneally) groups. The rats were sacrificed 7 days or 3 months following irradiation. At 3 months, the Morris water maze test was used to assess spatial learning and memory function in rats. The results demonstrated that the WBRT group demonstrated a significantly impaired cognitive performance, decreased numbers of hippocampal Cornu Ammonis (CA)1 neurons and upregulated expression of caspase-3 in the dentate gyrus compared with those in the control and nimodipine groups. Reverse transcription-quantitative polymerase chain reaction analysis demonstrated that the WBRT group exhibited increased ratio of B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax)/Bcl-2 compared with that in control and nimodipine groups on day 7 following irradiation. However, the WBRT group exhibited decreased levels of brain-derived neurotrophic factor (BDNF) compared with that in control and nimodipine groups at 3 months following brain irradiation. The levels of growth-associated protein 43 and amyloid precursor protein between the nimodipine group and WBRT group were not statistically significant. The present study demonstrated that neuron apoptosis may lead to delayed cognitive deficits in the hippocampus, in response to radiotherapy. The cognitive impairment may be alleviated in response to a calcium antagonist nimodipine. The molecular mechanisms involved in nimodipine-mediated protection against cognitive decline may involve the regulation of Bax/Bcl-2 and BDNF in the hippocampus.

Oncogenic KRAS suppresses store-operated Ca2+ entry and ICRAC through ERK pathway-dependent remodelling of STIM expression in colorectal cancer cell lines.

The KRAS GTPase plays a fundamental role in transducing signals from plasma membrane growth factor receptors to downstream signalling pathways controlling cell proliferation, survival and migration. Activating KRAS mutations are found in 20% of all cancers and in up to 40% of colorectal cancers, where they contribute to dysregulation of cell processes underlying oncogenic transformation. Multiple KRAS-regulated cell functions are also influenced by changes in intracellular Ca2+ levels that are concurrently modified by receptor signalling pathways. Suppression of intracellular Ca2+ release mechanisms can confer a survival advantage in cancer cells, and changes in Ca2+ entry across the plasma membrane modulate cell migration and proliferation. However, inconsistent remodelling of Ca2+ influx and its signalling role has been reported in studies of transformed cells. To isolate the interaction between altered Ca2+ handling and mutated KRAS in colorectal cancer, we have previously employed isogenic cell line pairs, differing by the presence of an oncogenic KRAS allele (encoding KRASG13D), and have shown that reduced Ca2+ release from the ER and mitochondrial Ca2+ uptake contributes to the survival advantage conferred by oncogenic KRAS. Here we show in the same cell lines, that Store-Operated Ca2+ Entry (SOCE) and its underlying current, ICRAC are under the influence of KRASG13D. Specifically, deletion of the oncogenic KRAS allele resulted in enhanced STIM1 expression and greater Ca2+ influx. Consistent with the role of KRAS in the activation of the ERK pathway, MEK inhibition in cells with KRASG13D resulted in increased STIM1 expression. Further, ectopic expression of STIM1 in HCT 116 cells (which express KRASG13D) rescued SOCE, demonstrating a fundamental role of STIM1 in suppression of Ca2+ entry downstream of KRASG13D. These results add to the understanding of how ERK controls cancer cell physiology and highlight STIM1 as an important biomarker in cancerogenesis.

Cell-derived micro-environment helps dental pulp stem cells promote dental pulp regeneration.

OBJECTIVES: The function of the dental pulp is closely connected to the extracellular matrix (ECM) structure, and ECM has received significant attention due to its biological functions for regulating cells. As such, the interaction between the ECM niche and cells is worth exploring for potential clinical uses. MATERIALS AND METHODS: In this study, dental pulp stem cell (DPSC)-derived ECM (DPM) was prepared through cell culture and decellularization to function as the cell niche, and changes in DPSC behaviour and histological analysis of dental pulp tissue regeneration were evaluated following the DPM culture. DPM promoted the replication of DPSCs and exhibited retention of their mineralization. Then, the DPM-based culture strategy under odontogenic culture medium was further investigated, and the mineralization-related markers showed that DPSCs were regulated towards odontogenic differentiation. Dental pulp-like tissue with well-arranged ECM was harvested after a 2-month subcutaneous implantation in nude mice with DPM application. Additionally, DPSCs cultured on the plastic culture surface showed the up-regulation of mineralization makers in vitro, but there was a disorder in matrix formation and mineralization when the cells were cultured in vivo. RESULTS AND CONCLUSIONS: DPM-based cultivation could serve as a cell niche and modulate DPSC behaviour, and this method also provided an alternative to harvest tissue-specific ECM and provided a strategy for ECM-cell interaction.

Golgi-Associated Protein Kinase C-ε Is Delivered to Phagocytic Cups: Role of Phosphatidylinositol 4-Phosphate.

Protein kinase C-ε (PKC-ε) at phagocytic cups mediates the membrane fusion necessary for efficient IgG-mediated phagocytosis. The C1B and pseudosubstrate (εPS) domains are necessary and sufficient for this concentration. C1B binds diacylglycerol; the docking partner for εPS is unknown. Liposome assays revealed that the εPS binds phosphatidylinositol 4-phosphate (PI4P) and PI(3,5)P2 Wortmannin, but not LY294002, inhibits PKC-ε concentration at cups and significantly reduces the rate of phagocytosis. As Wortmannin inhibits PI4 kinase, we hypothesized that PI4P mediates the PKC-ε concentration at cups and the rate of phagocytosis. PKC-ε colocalizes with the trans-Golgi network (TGN) PI4P reporter, P4M, suggesting it is tethered at the TGN. Real-time imaging of GFP-PKC-ε-expressing macrophages revealed a loss of Golgi-associated PKC-ε during phagocytosis, consistent with a Golgi-to-phagosome translocation. Treatment with PIK93, a PI4 kinase inhibitor, reduces PKC-ε at both the TGN and the cup, decreases phagocytosis, and prevents the increase in capacitance that accompanies membrane fusion. Finally, expression of the Golgi-directed PI4P phosphatase, hSac1-K2A, recapitulates the PIK93 phenotype, confirming that Golgi-associated PI4P is critical for efficient phagocytosis. Together these data are consistent with a model in which PKC-ε is tethered to the TGN via an εPS-PI4P interaction. The TGN-associated pool of PKC-ε concentrates at the phagocytic cup where it mediates the membrane fusion necessary for phagocytosis. The novelty of these data lies in the demonstration that εPS binds PI4P and PI(3,5)P2 and that PI4P is necessary for PKC-ε localization at the TGN, its translocation to the phagocytic cup, and the membrane fusion required for efficient Fc [γ] receptor-mediated phagocytosis.