Calmodulin Signaling Pathway Research Articles

Heat stress-induced NO enhanced perylenequinone biosynthesis of Shiraia sp. via calcium signaling pathway

Perylenequinones (PQs) are natural photosensitizing compounds used as photodynamic therapy, and heat stress (HS) is the main limiting factor of mycelial growth and secondary metabolism of fungi. This study aimed to unravel the impact of HS-induced Ca2+ and the calcium signaling pathway on PQ biosynthesis of Shiraia sp. Slf14(w). Meanwhile, the intricate interplay between HS-induced NO and Ca2+ and the calcium signaling pathway was investigated. The outcomes disclosed that Ca2+ and the calcium signaling pathway activated by HS could effectively enhance the production of PQs in Shiraia sp. Slf14(w). Further investigations elucidated the specific mechanism through which NO signaling molecules induced by HS act upon the Ca2+/CaM (calmodulin) signaling pathway, thus propelling PQ biosynthesis in Shiraia sp. Slf14(w). This was substantiated by decoding the downstream positioning of the CaM/CaN (calcineurin) pathway in relation to NO through comprehensive analyses encompassing transcript levels, enzyme assays, and the introduction of chemical agents. Concurrently, the engagement of Ca2+ and the calcium signaling pathway in heat shock signaling was also evidenced. The implications of our study underscore the pivotal role of HS-induced Ca2+ and the calcium signaling pathway, which not only participate in heat shock signal transduction but also play an instrumental role in promoting PQ biosynthesis. Consequently, our study not only enriches our comprehension of the mechanisms driving HS signaling transduction in fungi but also offers novel insights into the PQ synthesis paradigm within Shiraia sp. Slf14(w).Key points• The calcium signaling pathway was proposed to participate in PQ biosynthesis under HS.• HS-induced NO was revealed to act upon the calcium signaling pathway for the first time.

Using ultra-performance liquid chromatography with linear ion trap-electrostatic field orbitrap mass spectrometry, network pharmacology, and molecular docking to explore the constituent targets and action mechanisms of decoction of Angelica sinensis, Zingiberis Rhizoma Recens, and Mutton in the treatment of diarrhea-predominant irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a chronic intestinal disorder characterized by abdominal discomfort, stool characteristics, and changes in bowel habits. Among them, diarrhea-type (diarrhea-predominant irritable bowel syndrome, abbreviated as IBS-D) is the most common. Because its pathogenesis is not understood, symptomatic treatment is currently used in clinical practice, and its long-term effect is still unclear. Decoction of Angelica sinensis, Zingiberis Rhizoma Recens, and Mutton (DAZM) is a famous traditional Chinese medicine recipe created by Zhang Zhongjing, a famous doctor in the Eastern Han Dynasty 2000 years ago, and is still in use today. Our research team has previously investigated the clinical study of DAZM in the treatment of IBS-D and conducted animal experiment research, indicating that DAZM has a significant effect on improving IBS-D. Yet, there are few reports on the specific mechanism of action of DAZM in improving the treatment of IBS and related types. Most studies discuss and verify its efficacy and protection from a clinical perspective. For this reason, this research will explore the constituent targets and mechanisms of DAZM to improve the treatment of IBS-D, provide relevant scientific evidence, and also provide reference evidence for the efficacy of food therapy decoction in improving the treatment of diseases and mechanism to open up new experimental research ideas. Identification of drug ingredients and collection of targets for DAZM using ultra-performance liquid chromatography with linear ion trap-electrostatic field orbitrap mass spectrometry and the Bioinformatics Analysis Tool for Molecular Mechanisms of Traditional Chinese Medicine database, active ingredients were selected based on their oral bioavailability and drug-like properties. Obtained IBS-D targets using the GeneCards database, took the intersection of IBS-D targets and DAZM targets and obtained potential targets of DAZM for the treatment of IBS-D. Using Cytoscape software to draw a network diagram of "Food therapy decoction-ingredient-target-disease" and selected the ingredients with larger parameter values by topological analysis. Correlation analysis of the selected active and parametric ingredients with prominent symptoms of IBS-D using SymMap database, and selection of potential core ingredients. The construction of protein interaction networks from the String database and the selection of potential core targets. Gene Ontology functional and Kyoto Encyclopedia of Genes and Genomes signaling pathway enrichment analyses using the Metascape database, establishing the bioinformatic processes and signaling pathways involved. Molecular docking of core ingredients and potential core targets was performed using AutoDock Vina, and the results were visualized using Python molecule (PyMOL) and LigPlus+. Finally, based on the results of this research combined with previous literature reports, the discussion section of this paper summarizes in detail the key core ingredients, targets, and signaling pathways of DAZM in improving IBS-D. DAZM may act on eight potential core targets (threonine kinase 1, insulin, tumour necrosis factor, tumour protein p53, interleukin 6, epidermal growth factor receptor, connexin β1, and interleukin 1β) through eight core ingredients (Zingiberone, Shyobunone, Palmitic acid, Sebiferic acid, β-Bisabolene, β-Sitosterol, Stigmasterol, and Oleic acid). inhibit pro-inflammatory factors through Advanced Glycation End Products-Receptor (AGE-RAGE) signaling pathway, Cyclic Adenosine Monophosphate (cAMP) signaling pathway, MAPK signaling pathway, IL-17 signaling pathway, Calmodulin (CaM) signaling pathway, and other pathways. It can alleviate the inflammatory response, enhance the intestinal mucosal barrier and regulate intestinal motility, and play a role in the treatment and improvement of IBS-D. This research mainly found the mechanism of DAZM on IBS-D, which may involve multiple ingredients, multiple targets, and multiple pathways. DAZM with medicinal and edible functions can effectively improve the treatment of IBS-D. This kind of dietary therapy is suitable for long-term treatment and is worthy of promotion.

Commentary on: The actin bundling activity of ITPKA mainly accounts for its migration-promoting effect in lung cancer cells.

1,4,5-triphosphate 3-kinase A (ITPKA) was first described and characterized by Irvine et al. in 1986 and cloned by Takazawa et al. in 1990. It is one of the components of the Ca2+ and calmodulin signaling pathway and a substrate for cAMP-dependent kinase (PKA) and protein kinase C (PKC), and is mainly involved in the regulation of intracellular inositol polyphosphate signaling molecules. Through a series of studies, Sabine's team has found that ITPKA expression was up-regulated in a variety of cancer cells, and silencing ITPKA inhibited while overexpressing ITPKA promoted cancer cell migration in vitro and metastasis in vivo. The latest research from Sabine's team has demonstrated that in H1299 lung cancer cells, the mechanism by which ITPKA promoted migration and invasion was predominantly depending on the ability of binding to F-actin, which will induce cancer cells to form a tight flexible actin networks. Small molecule compounds targeting the IP3 kinase activity of ITPKA protein may only inhibit the migration and invasion of cancer cells caused by the enhanced ITPKA kinase activity under ATP stimulation, but not the cytoskeletal remodeling caused by the binding of ITPKA protein to F-actin and the driven migration and invasion of cancer cells. Therefore, targeted therapeutic strategy focusing on blocking the binding of ITPKA to F-actin is indispensable when designing the inhibitors targeting ITPKA protein.

Calmodulin activates the Hippo signaling pathway by promoting LATS1 kinase–mediated inhibitory phosphorylation of the transcriptional coactivator YAP

The Hippo signaling pathway regulates tissue growth and cell fate, and its dysregulation can induce tumorigenesis. When Hippo is activated by cell–cell contact, extracellular signals, or cell polarity among others, the large tumor suppressor 1 (LATS1) kinase catalyzes inhibitory phosphorylation of the transcriptional coactivator Yes-associated protein (YAP) to maintain YAP in the cytoplasm or promote its degradation. Separately, calmodulin is a Ca2+-dependent protein that modulates the activity of target proteins and regulates several signaling cascades; however, its potential role in the Hippo pathway has not been identified. Here, using diverse experimental approaches, including in vitro binding analyses, kinase assays, RT–PCR, and confocal microscopy, we reveal that calmodulin promotes Hippo signaling. We show that purified YAP and LATS1 bind directly to calmodulin and form a Ca2+-dependent ternary complex in vitro. Importantly, Ca2+/calmodulin directly stimulated the activity of LATS1 kinase. In cultured mammalian cells, we demonstrated that endogenous YAP and LATS1 coimmunoprecipitate with endogenous calmodulin. In cells with activated Hippo signaling, we show that calmodulin antagonism significantly (i) decreases YAP phosphorylation, (ii) increases expression of two Hippo target genes (connective tissue growth factor [CTGF] and cysteine-rich angiogenic inducer 61 [CYR61]) that regulate cell proliferation and tumor progression, and (iii) enhances the interaction of YAP with its major transcription factor, thereby facilitating transcription of target genes. Collectively, our data demonstrate that calmodulin activates the Hippo kinase cascade and inhibits YAP activity via a direct interaction with LATS1 and YAP, thereby uncovering previously unidentified crosstalk between the Ca2+/calmodulin and Hippo signaling pathways.

Naringenin enhances anti-proliferation effect of 1-ferrocenyl-3-(4-methylsulfonylphenyl) propen-1-one on two different cells via targeting calmodulin signaling pathway.

FMSP is a synthesized ferrocene derivative with anti-cancer characteristics on tumor cells. Naringenin is a polyphenolic flavonoid with anti-tumor ability. Cell viability and proliferation of two cancer cells and a normal cell line after treatment with these agents were determined with MTT assay. To predict the possible interaction between calmodulin (CaM) and FMSP and naringenin, docking studies were performed. By using fluorescence emission spectra, the effects of FMSP and naringenin on CaM structure and activity were studied. CaM-dependent activation of phosphodiesterase 1 (PDE1) by FMSP in relation to naringenin and their combination were compared. Effects of these compounds on PDE1 inhibition, cAMP accumulation, and cAMP-dependent protein kinase A (PKA) activation were assayed. The combination of FMSP and naringenin had more inhibitory effects on CaM structure than FMSP and naringenin alone. Results of docking analyses also confirmed efficient interaction of the two compounds with a hydrophobic pocket of calmodulin active site. Kinetic analyses of these agents' interaction with CaM showed FMSP and naringenin both competitively inhibited PDE1 activation without changing the Vmax parameter. FMSP and naringenin synergistically increased Km values at a higher level compared to FMSP or naringenin alone. The combination of these two agents also had more cytotoxic effects on cancer cells than FMSP alone. It was shown that mechanism of proliferation inhibition in both cancer cells by these compounds is based on CaM and consequent PDE inhibition followed by intracellular cAMP level elevation and increased PKA activity in a dose-dependent manner.

Neurogranin: A novel biomarker of Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD) is a progressive, incurable and fatal neurodegenerative disorder characterized by continuing cognitive decline. Early deficits of memory and other cognitive functions has closely related to synaptic loss in AD. Neurogranin (Ng) is a small protein located in postsynaptic neurons, dendrites and spines in brain structures like the hippocampus. Ng plays an crucial role in synaptic plasticity and long‐term potentiation mediated by calcium and calmodulin signalling pathway, which is essential to memory and learning functions. Considering the above mentioned facts, it seems that Ng can be novel biomarker of synaptic injury. The purposes of our investigation were the quantitive assessment of Ng levels in the CSF of AD patients and comparison with classical biomarkers of AD.MethodThe cerebrospinal fluid (CSF) levels of neurogranin and classical AD biomarkers, such as Aβ‐42, Aβ‐42/Aβ‐40, hTau and pTau181 were assessed by immunoenzyme assays. The study included 15 patients with AD and 15 non‐demented controls.ResultThe significantly higher concentration of Ng in cerebrospinal fluid of AD patients compared to non‐demented controls was observed. The CSF level of neurogranin was positively correlated with hTau and pTau181 and negatively with Aβ‐42/Aβ‐40 ratio.ConclusionThe Ng is a crucial indicator of synaptopathy in the AD.Our results suggest that Ng is a promising biomarker for AD, however, further studies on larger group patients are needed. Acknowledgement: The study was conducted with the use of equipment purchased by the Medical University of Białystok as part of the RPOWP 2007‐2013 funding, Priority I, Axis 1.1, contract No. UDA‐RPPD.01.01.00‐20001/15‐00 dated 26 and project № POWR.03.02.00‐00‐I051/16 from European Union funds, POWER 2014‐2020, grant № 04/IMSD/G/2019

The endosomal Q-SNARE, Syntaxin 7, defines a rapidly replenishing synaptic vesicle recycling pool in hippocampal neurons

Upon the arrival of repetitive stimulation at the presynaptic terminals of neurons, replenishment of readily releasable synaptic vesicles (SVs) with vesicles in the recycling pool is important for sustained neurotransmitter release. Kinetics of replenishment and the available pool size define synaptic performance. However, whether all SVs in the recycling pool are recruited for release with equal probability and speed is unknown. Here, based on comprehensive optical imaging of various presynaptic endosomal SNARE proteins in cultured hippocampal neurons, all of which are implicated in organellar membrane fusion in non-neuronal cells, we show that part of the recycling pool bearing the endosomal Q-SNARE, syntaxin 7 (Stx7), is preferentially mobilized for release during high-frequency repetitive stimulation. Recruitment of the SV pool marked with an Stx7-reporter requires actin polymerization, as well as activation of the Ca2+/calmodulin signaling pathway, reminiscent of rapidly replenishing SVs characterized previously in calyx of Held synapses. Furthermore, disruption of Stx7 function by overexpressing its N-terminal domain selectively abolished this pool. Thus, our data indicate that endosomal membrane fusion involving Stx7 forms rapidly replenishing vesicles essential for synaptic responses to high-frequency repetitive stimulation, and also highlight functional diversities of endosomal SNAREs in generating distinct exocytic vesicles in the presynaptic terminals.

The Ca2+-CaM Signaling Pathway Mediates Potassium Uptake by Regulating Reactive Oxygen Species Homeostasis in Tobacco Roots Under Low-K+ Stress.

Potassium (K+) deficiency severely threatens crop growth and productivity. Calcium (Ca2+) signaling and its sensors play a central role in the response to low-K+ stress. Calmodulin (CaM) is an important Ca2+ sensor. However, the mechanism by which Ca2+ signaling and CaM mediate the response of roots to low-K+ stress remains unclear. In this study, we found that the K+ concentration significantly decreased in both shoots and roots treated with Ca2+ channel blockers, a Ca2+ chelator, and CaM antagonists. Under low-K+ stress, reactive oxygen species (ROS) accumulated, and the activity of antioxidant enzymes, NAD kinase (NADK), and NADP phosphatase (NADPase) decreased. This indicates that antioxidant enzymes, NADK, and NADPase might be downstream target proteins in the Ca2+-CaM signaling pathway, which facilitates K+ uptake in plant roots by mediating ROS homeostasis under low-K+ stress. Moreover, the expression of NtCNGC3, NtCNGC10, K+ channel genes, and transporter genes was significantly downregulated in blocker-treated, chelator-treated, and antagonist-treated plant roots in the low K+ treatment, suggesting that the Ca2+-CaM signaling pathway may mediate K+ uptake by regulating the expression of these genes. Overall, this study shows that the Ca2+-CaM signaling pathway promotes K+ absorption by regulating ROS homeostasis and the expression of K+ uptake-related genes in plant roots under low-K+ stress.

The distinct roles of calcium in rapid control of neuronal glycolysis and the tricarboxylic acid cycle.

When neurons engage in intense periods of activity, the consequent increase in energy demand can be met by the coordinated activation of glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. However, the trigger for glycolytic activation is unknown and the role for Ca2+ in the mitochondrial responses has been debated. Using genetically encoded fluorescent biosensors and NAD(P)H autofluorescence imaging in acute hippocampal slices, here we find that Ca2+ uptake into the mitochondria is responsible for the buildup of mitochondrial NADH, probably through Ca2+ activation of dehydrogenases in the TCA cycle. In the cytosol, we do not observe a role for the Ca2+/calmodulin signaling pathway, or AMPK, in mediating the rise in glycolytic NADH in response to acute stimulation. Aerobic glycolysis in neurons is triggered mainly by the energy demand resulting from either Na+ or Ca2+ extrusion, and in mouse dentate granule cells, Ca2+ creates the majority of this demand.

Neurogranin: A Potential Biomarker of Neurological and Mental Diseases.

Neurogranin (Ng) is a small protein usually expressed in granule-like structures in pyramidal cells of the hippocampus and cortex. However, its clinical value is not fully clear so far. Currently, Ng is proved to be involved in synaptic plasticity, synaptic regeneration, and long-term potentiation mediated by the calcium- and calmodulin-signaling pathways. Due to both the synaptic integrity and function as the growing concerns in the pathogenesis of a wide variety of neurological and mental diseases, a series of researches published focused on the associations between Ng and these kinds of diseases in the past decade. Therefore, in this review, we highlight several diseases, which include, but are not limited to, Alzheimer’s disease, Parkinson disease, Creutzfeldt–Jakob disease, neuro-HIV, neurosyphilis, schizophrenia, depression, traumatic brain injury, and acute ischemic stroke, and summarize the associations between cerebrospinal fluid or blood-derived Ng with these diseases. We propose that Ng is a potential and promising biomarker to improve the diagnosis, prognosis, and severity evaluation of these diseases in the future.

Vasopressin-Independent Regulation of Aquaporin-2 by Tamoxifen in Kidney Collecting Ducts.

Arginine vasopressin (AVP) mediates water reabsorption in the kidney collecting ducts through regulation of aquaporin-2 (AQP2). Also, estrogen has been known to regulate AQP2. Consistently, we previously demonstrated that tamoxifen (TAM), a selective estrogen receptor modulator, attenuates the downregulation of AQP2 in lithium-induced nephrogenic diabetes insipidus (NDI). In this study, we investigated the AVP-independent regulation of AQP2 by TAM and the therapeutic effect of TAM on the dysregulation of AQP2 and impaired urinary concentration in a unilateral ureteral obstruction (UUO) model. Primary cultured inner medullary collecting duct (IMCD) cells from kidneys of male Sprague-Dawley rats were treated with TAM. Rats subjected to 7 days of UUO were treated with TAM by oral gavage. Changes of intracellular trafficking and expression of AQP2 were evaluated by quantitative PCR, Western blotting, and immunohistochemistry. TAM induced AQP2 protein expression and intracellular trafficking in primary cultured IMCD cells, which were independent of the vasopressin V2 receptor (V2R) and cAMP activation, the critical pathways involved in AVP-stimulated regulation of AQP2. TAM attenuated the downregulation of AQP2 in TGF-β treated IMCD cells and IMCD suspensions prepared from UUO rats. TAM administration in vivo attenuated the downregulation of AQP2, associated with an improvement of urinary concentration in UUO rats. In addition, TAM increased CaMKII expression, suggesting that calmodulin signaling pathway is likely to be involved in the TAM-mediated AQP2 regulation. In conclusion, TAM is involved in AQP2 regulation in a vasopressin-independent manner and improves urinary concentration by attenuating the downregulation of AQP2 and maintaining intracellular trafficking in UUO.

Downstream components of the calmodulin signaling pathway in the rice salt stress response revealed by transcriptome profiling and target identification

BackgroundCalmodulin (CaM) is an important calcium sensor protein that transduces Ca2+ signals in plant stress signaling pathways. A previous study has revealed that transgenic rice over-expressing the calmodulin gene OsCam1–1 (LOC_Os03g20370) is more tolerant to salt stress than wild type. To elucidate the role of OsCam1–1 in the salt stress response mechanism, downstream components of the OsCam1–1-mediated response were identified and investigated by transcriptome profiling and target identification.ResultsTranscriptome profiling of transgenic ‘Khao Dawk Mali 105’ rice over-expressing OsCam1–1 and wild type rice showed that overexpression of OsCam1–1 widely affected the expression of genes involved in several cellular processes under salt stress, including signaling, hormone-mediated regulation, transcription, lipid metabolism, carbohydrate metabolism, secondary metabolism, photosynthesis, glycolysis, tricarboxylic acid (TCA) cycle and glyoxylate cycle. Under salt stress, the photosynthesis rate in the transgenic rice was slightly lower than in wild type, while sucrose and starch contents were higher, suggesting that energy and carbon metabolism were affected by OsCam1–1 overexpression. Additionally, four known and six novel CaM-interacting proteins were identified by cDNA expression library screening with the recombinant OsCaM1. GO terms enriched in their associated proteins that matched those of the differentially expressed genes affected by OsCam1–1 overexpression revealed various downstream cellular processes that could potentially be regulated by OsCaM1 through their actions.ConclusionsThe diverse cellular processes affected by OsCam1–1 overexpression and possessed by the identified CaM1-interacting proteins corroborate the notion that CaM signal transduction pathways compose a complex network of downstream components involved in several cellular processes. These findings suggest that under salt stress, CaM activity elevates metabolic enzymes involved in central energy pathways, which promote or at least maintain the production of energy under the limitation of photosynthesis.

Calcium sequestration by fungal melanin inhibits calcium-calmodulin signalling to prevent LC3-associated phagocytosis.

LC3-associated phagocytosis (LAP) is a non-canonical autophagy pathway regulated by Rubicon, with an emerging role in immune homeostasis and antifungal host defence. Aspergillus cell wall melanin protects conidia (spores) from killing by phagocytes and promotes pathogenicity through blocking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent activation of LAP. However, the signalling regulating LAP upstream of Rubicon and the mechanism of melanin-induced inhibition of this pathway remain incompletely understood. Herein, we identify a Ca2+ signalling pathway that depends on intracellular Ca2+ sources from endoplasmic reticulum, endoplasmic reticulum-phagosome communication, Ca2+ release from phagosome lumen and calmodulin (CaM) recruitment, as a master regulator of Rubicon, the phagocyte NADPH oxidase NOX2 and other molecular components of LAP. Furthermore, we provide genetic evidence for the physiological importance of Ca2+-CaM signalling in aspergillosis. Finally, we demonstrate that Ca2+ sequestration by Aspergillus melanin inside the phagosome abrogates activation of Ca2+-CaM signalling to inhibit LAP. These findings reveal the important role of Ca2+-CaM signalling in antifungal immunity and identify an immunological function of Ca2+ binding by melanin pigments with broad physiological implications beyond fungal disease pathogenesis.

Suppression of a methionine synthase by calmodulin under environmental stress in the entomopathogenic fungus Beauveria bassiana.

Methionine synthase (MetE, EC 2.1.1.14) catalyses the final step in the methionine biosynthetic pathway. Methionine biosynthesis plays a major role in protein biogenesis and is the source of S-adenosyl methionine (SAM), the universal donor of methyl groups. In this study, we demonstrated that BbMetE acts as a typical MetE enzyme in the entomopathogenic fungus Beauveria bassiana. In addition, we found that BbMetE binds to calmodulin (CaM) in vitro and in vivo. The functional role of CaM binding to BbMetE was to negatively regulate BbMetE activity in B. bassiana. Our proton-nuclear magnetic resonance data revealed that CaM inhibitor W-7 increases methionine content in B. bassiana, suggesting that CaM negatively regulates the BbMetE activity. Environmental stress stimuli such as salt, H2 O2 and heat suppressed BbMetE activity in B. bassiana. W-7 reversed this effect, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbMetE plays an important role in methionine biosynthesis, which is mediated by environmental stress stimuli via the CaM signalling pathway.

Effect of calcium on sporulation of Taiwanofungus camphoratus in submerged fermentation

Taiwanofungus camphoratus is a valuable and rare medicinal mushroom with various bioactivities, such as liver protection and anti-cancer. T. camphoratus can produce many arthroconidia at the end of submerged fermentation, but molecular mechanism underlying this submerged conidiation remains unknown. In this study, we found that Ca²⁺ concentration in culture medium significantly affected the arthroconidium production of T. camphoratus. Then, we identified two proteins (CaM and HSP90) involved in Ca²⁺/calmodulin signaling pathway and one protein (AbaA) involved in FluG-mediated conidiation pathway by two-dimensional electrophoresis analyses. Furthermore, we proposed a Ca²⁺/calmodulin- and FluG-mediated signaling pathway by bioinformatics analysis. By real-time quantitative PCR analyses of 23 key genes in the Ca²⁺/calmodulin- and FluG-mediated conidiation pathway, we found that expression levels of 7 genes (crz1, hsp90, flbB, brlA, abaA, wetA and fadA) showed significant responses to Ca²⁺ concentration in fermentation medium. Our research is beneficial for elucidating the underlying mechanism of submerged fermentation conidiation for T. camphoratus.

Delineating the Common Biological Pathways Perturbed by ASD's Genetic Etiology: Lessons from Network-Based Studies.

In recent decades it has become clear that Autism Spectrum Disorder (ASD) possesses a diverse and heterogeneous genetic etiology. Aberrations in hundreds of genes have been associated with ASD so far, which include both rare and common variations. While one may expect that these genes converge on specific common molecular pathways, which drive the development of the core ASD characteristics, the task of elucidating these common molecular pathways has been proven to be challenging. Several studies have combined genetic analysis with bioinformatical techniques to uncover molecular mechanisms that are specifically targeted by autism-associated genetic aberrations. Recently, several analysis have suggested that particular signaling mechanisms, including the Wnt and Ca2+/Calmodulin-signaling pathways are often targeted by autism-associated mutations. In this review, we discuss several studies that determine specific molecular pathways affected by autism-associated mutations, and then discuss more in-depth into the biological roles of a few of these pathways, and how they may be involved in the development of ASD. Considering that these pathways may be targeted by specific pharmacological intervention, they may prove to be important therapeutic targets for the treatment of ASD.

ATP2B1 gene Silencing Increases Insulin Sensitivity through Facilitating Akt Activation via the Ca2+/calmodulin Signaling Pathway and Ca2+-associated eNOS Activation in Endothelial Cells.

Endothelial cell insulin resistance may be partially responsible for the higher risk of atherosclerosis and cardiovascular disease in populations with insulin resistance and type 2 diabetes mellitus (T2DM). A genome-wide association study revealed a significant association between the ATPase plasma membrane Ca2+ transporting 1 (ATP2B1) gene and T2DM in two community-based cohorts from the Korea Association Resource Project. However, little is known about the implication of the ATP2B1 gene on T2DM. In the present study, we investigated the role of the ATP2B1 gene in endothelial cell insulin sensitivity. ATP2B1 gene silencing resulted in enhanced intracellular calcium concentrations and increased insulin-induced Akt activation compared to that in the negative siRNA-transfected HUVECs (Human Umbilical Vein Endothelial Cells). The elevated insulin sensitivity mediated by ATP2B1 gene silencing was Ca2+/calmodulin-dependent, as verified by administration of the calcium chelator BAPTA-AM or the calmodulin-specific antagonist W7. Moreover, higher levels of phosphorylation of eNOS (Ser1177) were observed in ATP2B1-silenced HUVECs. In addition to BAPTA-AM and W7, L-NAME, an eNOS antagonist, abolished insulin-induced Akt phosphorylation at Ser473 in both si-Neg and si-ATP2B1-transfected endothelial cells. These results indicate that the enhanced insulin sensitivity in ATP2B1-silenced endothelial cells is alternatively dependent on an increase in intracellular Ca2+ and the subsequent activation of the Ca2+/calmodulin/eNOS/Akt signaling pathway. In summary, ATP2B1 gene silencing increased insulin sensitivity in endothelial cells by directly modulating the Ca2+/calmodulin signaling pathway and via the Ca2+/calmodulin/eNOS/Akt signaling pathway alternatively.

Calmodulin-mediated suppression of 2-ketoisovalerate reductase in Beauveria bassiana beauvericin biosynthetic pathway.

Ketoisovalerate reductase (KIVR, E.C. 1.2.7.7) mediates the specific reduction of 2-ketoisovalerate (2-Kiv) to d-hydroxyisovalerate (d-Hiv), a precursor for beauvericin biosynthesis. Beauvericin, a famous mycotoxin produced by many fungi, is a cyclooligomer depsipeptide, which has insecticidal, antimicrobial, antiviral, and cytotoxic activities. In this report, we demonstrated that Beauveria bassiana 2-ketoisovalerate reductase (BbKIVR) acts as a typical KIVR enzyme in the entomopathogenic fungus B. bassiana. In addition, we found that BbKIVR interacts with calmodulin (CaM) in vitro and in vivo. The functional role of CaM-binding to BbKIVR was to negatively regulate the BbKIVR activity in B. bassiana. Environmental stimuli such as light and salt stress suppressed BbKIVR activity in B. bassiana. Interestingly, this negative effect of BbKIVR activity by light and salt stress was recovered by CaM inhibitors, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbKIVR plays an important role in the beauvericin biosynthetic pathway mediated by environmental stimuli such as light and salt stress via the CaM signaling pathway.

Comparative proteomic analysis of the response to silver ions and yeast extract in Salvia miltiorrhiza hairy root cultures

Biotic and abiotic stresses can inhibit plant growth, resulting in losses of crop productivity. However, moderate adverse stress can promote the accumulation of valuable natural products in medicinal plants. Elucidating the underlying molecular mechanisms thus might help optimize the variety of available plant medicinal materials and improve their quality. In this study, Salvia miltiorrhiza hairy root cultures were employed as an in vitro model of the Chinese herb Danshen. A comparative proteomic analysis using 2-dimensional gel electrophoresis and MALDI-TOF-MS was performed. By comparing the gel images of groups exposed to the stress of yeast extract (YE) combined with Ag+ and controls, 64 proteins were identified that showed significant changes in protein abundance for at least one time point after treatment. According to analysis based on the KEGG and related physiological experimental verification, it was found that YE and Ag+ stress induced a burst of reactive oxygen species and activated the Ca2+/calmodulin signaling pathway. Expression of immune-suppressive proteins increased. Epidermal cells underwent programmed cell death. Energy metabolism was enhanced and carbon metabolism shifted to favor the production of secondary metabolites such as lignin, tanshinone and salvianolic acids. The tanshinone and salvianolic acids were deposited on the collapsed epidermal cells forming a physicochemical barrier. The defense proteins and these natural products together enhanced the stress resistance of the plants. Since higher levels of natural products represent good quality in medicinal materials, this study sheds new light on quality formation mechanisms of medicinal plants and will hopefully encourage further research on how the planting environment affects the efficacy of herbal medicines.

Estrogen Receptor Alpha Utilizes TRP Channel 6 in Cancer Cell Growth

The rapid signaling effects of the hormone estrogen (E2) are mediated through estrogen receptor alpha (ERα) that activates a Ca2+/calmodulin signaling pathway involving CaM KK, CaM KI, and ERK. Additionally, expression of transient receptor potential (TRP) channels, which are Ca2+ channels, may correlate with breast cancer cell growth. In this family of channels, TRPC6 has been shown to be expressed in MCF‐7 breast cancer cells and involved in ERK activation. Since both ERα and TRPC6 increase intracellular calcium levels, ERK activation, and cell growth our goal was to examine if ERα cooperates with TRPC6 to increase CaM Kinase and ERK phosphorylation as well as MCF‐7 cell growth. E2 treatment of MCF‐7 cells led to a significant rise in phosphorylation of CaM KI and its downstream target, ERK, and this effect was blocked by pretreatment with the ERa antagonist MPP. Treatment of MCF‐7 cells with E2 stimulated an increase in MCF‐7 cell growth that was blocked by pretreatment with MPP, but not by pretreatment with the ERb antagonist PHTPP. Interestingly, treatment of cells with the TRP channel inhibitor APB blocked E2 activation of ERK and cell growth. Immunoprecipitation (IP) of endogenous ERa pulled down TRPC6 as did the reciprocal IP from MCF‐7 cells. Confocal microscopy also revealed co‐localization of the proteins in MCF‐7 cells. Our data suggest E2 rapidly activates CaM KI and ERK via ERa and TRP channels and ERa may associate with TRPC6 to regulate breast cancer cell growth.Support or Funding InformationThe Paul K. and Evalyn E. C. Richter Memorial Fund.This work was supported through a Life Science grant from the M.J. Murdock Charitable Trust to J.M.S. grant #2011267.