Physiological roles of the Ca2+/CaM-dependent protein kinase cascade in health and disease

Sex-specific sequels of early life stress on serine/threonine kinase activity in visceral adipose tissue from obese mice

Adverse childhood experiences (ACEs) are an established independent risk factor for chronic disease including obesity and hypertension; however, only women exposed to multiple ACEs show a positive relationship with BMI. Our lab has reported that maternal separation and early weaning (MSEW), a mouse model of early life stress, induces sex-specific mechanisms underlying greater blood pressure response to a chronic high fat diet (HF). Specifically, female MSEW mice fed a HF display exacerbated perigonadal white adipose tissue (pgWAT) expansion and a metabolic syndrome-like phenotype compared to control counterparts, whereas hypertension is caused by sympathoactivation in male MSEW mice. Thus, this study aimed to determine whether there is a sex-specific serine/threonine kinase (STKA) activity in pgWAT adipose tissue associated with early life stress. Frozen pgWAT was collected from MSEW and control, male and female mice fed a HF to assess STKA activity using the Pamstation12 instrument. Overall, MSEW induces significant reduction of 7 phosphokinases (|Z| >=1.5) in females (QIK, MLK, PKCH, MST, STE7, PEK, FRAY) and 5 in males (AKT, SGK, P38, MARK, CDK), while 15 were downregulated in both sexes (DMPK, PKA, PKG, RSK, PLK, DYRK, NMO, CAMK1, JNK, PAKA, RAD53, ERK, PAKB, PKD, PIM, AMPK). This data provides new insights into the sex-specific dysregulation of the molecular network controlling cellular phosphorylation signals in visceral adipose tissue and identifies possible target phosphokinases implicated in adipocyte hypertrophy as a result of exposure to early life stress. Identifying functional metabolic signatures is critical to elucidate the underlying molecular mechanisms behind the sex-specific obesity risk associated with early life stress.

Vitamin C Modes of Action in Calcium-Involved Signaling in the Brain

Vitamin C (ascorbic acid) is well known for its potent antioxidant properties, as it can neutralize ROS and free radicals, thereby protecting cellular elements from oxidative stress. It predominantly exists as an ascorbate anion and after oxidation to dehydroascorbic acid and further breakdown, is removed from the cells. In nervous tissue, a progressive decrease in vitamin C level or its prolonged deficiency have been associated with an increased risk of disturbances in neurotransmission, leading to dysregulation in brain function. Therefore, understanding the regulatory function of vitamin C in antioxidant defence and identification of its molecular targets deserves more attention. One of the key signalling ions is calcium and a transient rise in its concentration is crucial for all neuronal processes. Extracellular Ca²⁺ influx (through specific ion channels) or Ca²⁺ release from intracellular stores (endoplasmic reticulum, mitochondria) are precisely controlled. Ca²⁺ regulates the functioning of the CNS, including growth, development, myelin formation, synthesis of catecholamines, modulation of neurotransmission and antioxidant protection. A growing body of evidence indicates a unique role for vitamin C in these processes. In this short review, we focus on vitamin C in the regulation of calcium-involved pathways under physiological and stress conditions in the brain.

Functional regionalization of the differentiating cerebellar Purkinje cell population occurs in an activity-dependent manner

Introduction

The cerebellum is organized into functional regions each dedicated to process different motor or sensory inputs for controlling different locomotor behaviors. This functional regionalization is prominent in the evolutionary conserved single-cell layered Purkinje cell (PC) population. Fragmented gene expression domains suggest a genetic organization of PC layer regionalization during cerebellum development. However, the establishment of such functionally specific domains during PC differentiation remained elusive.

Methods and results

We show the progressive emergence of functional regionalization of PCs from broad responses to spatially restricted regions in zebrafish by means of in vivo Ca2+-imaging during stereotypic locomotive behavior. Moreover, we reveal that formation of new dendritic spines during cerebellar development using in vivo imaging parallels the time course of functional domain development. Pharmacological as well as cell-type specific optogenetic inhibition of PC neuronal activity results in reduced PC dendritic spine density and an altered stagnant pattern of functional domain formation in the PC layer.

Discussion

Hence, our study suggests that functional regionalization of the PC layer is driven by physiological activity of maturing PCs themselves.

Calcium Signalling in Heart and Vessels: Role of Calmodulin and Downstream Calmodulin-Dependent Protein Kinases

Cardiovascular disease is the major cause of death worldwide. The success of medication and other preventive measures introduced in the last century have not yet halted the epidemic of cardiovascular disease. Although the molecular mechanisms of the pathophysiology of the heart and vessels have been extensively studied, the burden of ischemic cardiovascular conditions has risen to become a top cause of morbidity and mortality. Calcium has important functions in the cardiovascular system. Calcium is involved in the mechanism of excitation-contraction coupling that regulates numerous events, ranging from the production of action potentials to the contraction of cardiomyocytes and vascular smooth muscle cells. Both in the heart and vessels, the rise of intracellular calcium is sensed by calmodulin, a protein that regulates and activates downstream kinases involved in regulating calcium signalling. Among them is the calcium calmodulin kinase family, which is involved in the regulation of cardiac functions. In this review, we present the current literature regarding the role of calcium/calmodulin pathways in the heart and vessels with the aim to summarize our mechanistic understanding of this process and to open novel avenues for research.

Calmodulin Binding Activates Chromobacterium CopC Effector to ADP-Riboxanate Host Apoptotic Caspases

Blocking host cell death is an important virulence strategy employed by many bacterial pathogens. We recently reported that Shigella flexneri inhibits host pyroptosis by delivering a type III secretion system (T3SS) effector OspC3 that catalyzes a novel arginine ADP-riboxanation modification on caspase-4/11. Here, we investigated the OspC3 homologue CopC from Chromobacterium violaceum, an opportunistic but sometimes deadly bacterial pathogen. CopC bears the same arginine ADP-riboxanase activity as OspC3, but with a different substrate specificity. Through proteomic analysis, we first identified host calmodulin (CaM) as a binding partner of CopC. The analyses additionally revealed that CopC preferably modifies apoptotic caspases including caspase-7, -8 and -9. This results in suppression of both extrinsic and intrinsic apoptosis programs in C. violaceum-infected cells. Biochemical reconstitution showed that CopC requires binding to CaM, specifically in the calcium-free state, to achieve efficient ADP-riboxanation of the caspases. We determined crystal structure of the CaM-CopC-CASP7 ternary complex, which illustrates the caspase recognition mechanism and a unique CaM-binding mode in CopC. Structure-directed mutagenesis validated the functional significance of CaM binding for stimulating CopC modification of its caspase substrates. CopC adopts an ADP-ribosyltransferase-like fold with a unique His-Phe-Glu catalytic triad, featuring two acidic residues critical for site-specific arginine ADP-riboxanation. Our study expands and deepens our understanding of the OspC family of ADP-riboxanase effectors.

An Integrated Analysis Reveals Geniposide Extracted From Gardenia jasminoides J.Ellis Regulates Calcium Signaling Pathway Essential for Influenza A Virus Replication

Geniposide, an iridoid glycoside purified from the fruit of Gardenia jasminoides J.Ellis, has been reported to possess pleiotropic activity against different diseases. In particular, geniposide possesses a variety of biological activities and exerts good therapeutic effects in the treatment of several strains of the influenza virus. However, the molecular mechanism for the therapeutic effect has not been well defined. This study aimed to investigate the mechanism of geniposide on influenza A virus (IAV). The potential targets and signaling pathways of geniposide in the IAV infection were predicted using network pharmacology analysis. According to the result of network pharmacology analysis, we validated the calcium signaling pathway induced by IAV and investigated the effect of geniposide extracted from Gardenia jasminoides J.Ellis on this pathway. The primary Gene Ontology (GO) biological processes and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways KEGG enrichment analysis indicated that geniposide has a multi-target and multi-pathway inhibitory effect against influenza, and one of the mechanisms involves calcium signaling pathway. In the current study, geniposide treatment greatly decreased the levels of RNA polymerase in HEK-293T cells infected with IAV. Knocking down CAMKII in IAV-infected HEK-293T cells enhanced virus RNA (vRNA) production. Geniposide treatment increased CAMKII expression after IAV infection. Meanwhile, the CREB and c-Fos expressions were inhibited by geniposide after IAV infection. The experimental validation data showed that the geniposide was able to alleviate extracellular Ca²⁺ influx, dramatically decreased neuraminidase activity, and suppressed IAV replication in vitro via regulating the calcium signaling pathway. These anti-IAV effects might be related to the disrupted interplay between IAV RNA polymerase and CAMKII and the regulation of the downstream calcium signaling pathway essential for IAV replication. Taken together, the findings reveal a new facet of the mechanism by which geniposide fights IAV in a way that depends on CAMKII replication.

MicroRNA-378 regulates adipogenic differentiation in bovine intramuscular preadipocytes by targeting CaMKK2

Intramuscular fat, as one of the most important palatability attribute of beef carcase, is the primary determinant of beef quality. The research of adipogenesis mechanism would provide new insight into intramuscular fatty deposition. Here, the role of microRNA-378 was investigated during bovine adipogenic differentiation. It was revealed that miR-378 expression exists variably in bovine major tissue and organs by RT-qPCR. It was predicted that miR-378 targets CaMKK2, as an AMPKα kinase, by DIANA Tools. For better research, primary preadipocytes with stable transfection for up-/down-regulated expression of miR-378 were constructed by lentiviral vectors with GFP gene. The analyses of qPCR showed that PPARγ and adiponectin mRNA levels increased, but C/EBPβ, pref-1 and CaMKK2 mRNA levels decreased during adipogenic differentiation. When miR-378 was overexpressed, preadipocytes proliferation became slower, there are more cellular lipid droplets, and PPARγ and C/EBPβ mRNA levels were higher, but pref-1, adiponectin and CaMKK2 were lower than control groups. Luciferase assay and western blot analysis validated that miR-378 binds the nucleotide sites of the 3′- untranslated region of CaMKK2, which inhibits the mRNA and protein expression of CaMKK2. These findings suggest that miR-378 promotes adipogenic differentiation in bovine intramuscular preadipocytes by targeting CaMKK2 via AMPK signalling pathway.

Osteocyte calcium signaling - A potential translator of mechanical load to mechanobiology

Osteocytes are embedded dendritic bone cells; by virtue of their position in bone tissue, ability to coordinate bone building osteoblasts and resorbing osteoclasts, and sensitivity to tissue level mechanical loading, they serve as the resident bone mechanosensor. The mechanisms osteocytes use to change mechanical loading into biological signals that drive tissue level changes has been well studied over the last 30 years, however the ways loading parameters are encoded at the cellular level are still not fully understood. Calcium signaling is a first messenger signal exhibited by osteocytes in response to mechanical forces. A body of work interrogating the mechanisms of osteocyte calcium signaling exists and is presently expanding, presenting the opportunity to better understand the relationship between calcium signaling characteristics and tuned osteocyte responses to tissue level strain features (e.g. magnitude, duration, frequency). This review covers the history of osteocyte load induced calcium signaling and highlights potential cellular mechanisms used by osteocytes to turn details about loading parameters into biological events.

CaMKIIγ regulates the viability and self-renewal of acute myeloid leukaemia stem-like cells by the Alox5/NF-κB pathway

Acute myeloid leukaemia (AML) is a frequently fatal malignant disease of haematopoietic stem and progenitor cells. The molecular and phenotypic characteristics of AML are highly heterogeneous. Our previous study concluded that CaMKIIγ was the trigger of chronic myeloid leukaemia progression from the chronic phase to blast crisis, but how CaMKIIγ influences AML stem-like cells remains elusive. In this study, we found that CaMKIIγ was overexpressed in AML patients and AML cell lines, as measured by qRT-PCR and Western blot assays. Moreover, CaMKIIγ decreased when the disease was in remission. Using an shRNA lentivirus expression system, we established CaMKIIγ stable-knockdown AML cell lines and found that knockdown of CaMKIIγ inhibited the viability and self-renewal of AML stem-like cell lines. Additionally, the ratio of CD₃₄ ⁺ AML cell lines decreased, and CaMKIIγ knockdown induced the downregulation of Alox5 levels. We further detected downstream molecules of the Alox5/NF-κB pathway and found that c-myc and p-IκBα decreased while total IκBα remained normal. In conclusion, our study describes a new role for CaMKIIγ as a stem-like cell marker that is highly regulated by the Alox5/NF-κB pathway in AML stem-like cells. CaMKIIγ can participate in the viability and self-renewal of AML stem-like cells by regulating the Alox5/NF-κB pathway.

Stabilization of Protein-Protein Interactions between CaMKK2 and 14-3-3 by Fusicoccins

Ca²⁺/calmodulin-dependent protein kinase kinase 2 (CaMKK2) regulates several key physiological and pathophysiological processes, and its dysregulation has been implicated in obesity, diabetes, and cancer. CaMKK2 is inhibited through phosphorylation in a process involving binding to the scaffolding 14-3-3 protein, which maintains CaMKK2 in the phosphorylation-mediated inhibited state. The previously reported structure of the N-terminal CaMKK2 14-3-3-binding motif bound to 14-3-3 suggested that the interaction between 14-3-3 and CaMKK2 could be stabilized by small-molecule compounds. Thus, we investigated the stabilization of interactions between CaMKK2 and 14-3-3γ by Fusicoccin A and other fusicoccanes-diterpene glycosides that bind at the interface between the 14-3-3 ligand binding groove and the 14-3-3 binding motif of the client protein. Our data reveal that two of five tested fusicoccanes considerably increase the binding of phosphopeptide representing the 14-3-3 binding motif of CaMKK2 to 14-3-3γ. Crystal structures of two ternary complexes suggest that the steric contacts between the C-terminal part of the CaMKK2 14-3-3 binding motif and the adjacent fusicoccane molecule are responsible for differences in stabilization potency between the study compounds. Moreover, our data also show that fusicoccanes enhance the binding affinity of phosphorylated full-length CaMKK2 to 14-3-3γ, which in turn slows down CaMKK2 dephosphorylation, thus keeping this protein in its phosphorylation-mediated inhibited state. Therefore, targeting the fusicoccin binding cavity of 14-3-3 by small-molecule compounds may offer an alternative strategy to suppress CaMKK2 activity by stabilizing its phosphorylation-mediated inhibited state.

Physiological and Transcriptomic Analyses Elucidate That Exogenous Calcium Can Relieve Injuries to Potato Plants (Solanum tuberosum L.) under Weak Light

Light is one of the most important abiotic factors for most plants, which affects almost all growth and development stages. In this study, physiological indicators suggest that the application of exogenous Ca²⁺ improves photosynthesis and changes phytohormone levels. Under weak light, photosynthetic parameters of the net photosynthetic rate (P_N), stomatal conductance (Gs), and transpiration rate (Tr) decreased; the antioxidation systems peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) reduced; the degrees of malondialdehyde (MDA), H₂O₂, and superoxide anion (O₂⁻) free radical damage increased; while exogenous Ca²⁺ treatment was significantly improved. RNA-seq analysis indicated that a total of 13,640 differently expressed genes (DEGs) were identified and 97 key DEGs related to hormone, photosynthesis, and calcium regulation were differently transcribed. Gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses, plant hormone signal transduction, photosynthesis, carbon metabolism, and phenylpropanoid biosynthesis were significantly enriched. Additionally, quantitative real-time PCR (qRT-PCR) analysis confirmed some of the key gene functions in response to Ca²⁺. Overall, these results provide novel insights into the complexity of Ca²⁺ to relieve injuries under weak light, and they are helpful for potato cultivation under weak light stress.

A Multiomics Study To Unravel the Effects of Developmental Exposure to Endosulfan in Rats: Molecular Explanation for Sex-Dependent Effects

Exposure to low levels of environmental contaminants, including pesticides, induces neurodevelopmental toxicity. Environmental and food contaminants can reach the brain of the fetus, affecting brain development and leading to neurological dysfunction. The pesticide endosulfan is a persistent pollutant, and significant levels still remain detectable in the environment although its use is banned in some countries. In rats, endosulfan exposure during brain development alters motor activity, coordination, learning, and memory, even several months after uptake, and does so in a sex-dependent way. However, the molecular mechanisms driving these effects have not been studied in detail. In this work, we performed a multiomics study in cerebellum from rats exposed to endosulfan during embryonic development. Pregnant rats were orally exposed to a low dose (0.5 mg/kg) of endosulfan, daily, from gestational day 7 to postnatal day 21. The progeny was evaluated for cognitive and motor functions at adulthood. Expression of messenger RNA and microRNA genes, as well as protein and metabolite levels, were measured on cerebellar samples from males and females. An integrative analysis was conducted to identify altered processes under endosulfan effect. Effects between males and females were compared. Pathways significantly altered by endosulfan exposure included the phosphatidylinositol signaling system, calcium signaling, the cGMP-PKG pathway, the inflammatory and immune system, protein processing in the endoplasmic reticulum, and GABA and taurine metabolism. Sex-dependent effects of endosulfan in the omics results that matched sex differences in cognitive and motor tests were found. These results shed light on the molecular basis of impaired neurodevelopment and contribute to the identification of new biomarkers of neurotoxicity.

Immunohistochemical Expression of Calmodulin in Cutaneous Lichen Planus: A Case-Control Study

Background:

Calmodulin (CaM) is a multifunctional intermediate messenger protein that plays important role in cell motility, proliferation, and apoptosis. Therefore, it is thought to be involved in various ways in the apoptotic processes which are implicated in the pathogenesis of lichen planus.

Objective:

The aim of this study was to evaluate the immunohistochemical expression of CaM in lichen planus lesions in comparison to normal control skin to throw light on its possible role in disease pathogenesis.

Patients and Methods:

This case–control study was conducted on 50 patients with lichen planus, in addition to 20 age- and sex-matched healthy individuals. Skin biopsy specimens were taken from lesional skin of lichen planus patients as well as normal skin of controls. All were examined for immunohistochemical expression of CaM antibody.

Results:

There was statistically significant increase of the immunohistochemical expression of CaM in lesional skin of lichen planus patients compared with normal skin of controls (Chi-square test, P < 0.001). No significant correlation could be detected between CaM expression in lesional skin and the studied clinical parameters of lichen planus patients.

Limitations:

Tha main limitation of this study is its small sample size.

Conclusion:

CaM is upregulated in cutaneous lichen planus lesions suggesting a possible role in disease pathogenesis. Targeting CaM is expected to be a novel strategy for treatment of lichen planus.

CaMKK2 in myeloid cells is a key regulator of the immune-suppressive microenvironment in breast cancer

Tumor-associated myeloid cells regulate tumor growth and metastasis, and their accumulation is a negative prognostic factor for breast cancer. Here we find calcium/calmodulin-dependent kinase kinase (CaMKK2) to be highly expressed within intratumoral myeloid cells in mouse models of breast cancer, and demonstrate that its inhibition within myeloid cells suppresses tumor growth by increasing intratumoral accumulation of effector CD8+ T cells and immune-stimulatory myeloid subsets. Tumor-associated macrophages (TAMs) isolated from Camkk2-/- mice expressed higher levels of chemokines involved in the recruitment of effector T cells compared to WT. Similarly, in vitro generated Camkk2-/- macrophages recruit more T cells, and have a reduced capability to suppress T cell proliferation, compared to WT. Treatment with CaMKK2 inhibitors blocks tumor growth in a CD8+ T cell-dependent manner, and facilitates a favorable reprogramming of the immune cell microenvironment. These data, credential CaMKK2 as a myeloid-selective checkpoint, the inhibition of which may have utility in the immunotherapy of breast cancer.

Calcium channels and cancer stem cells

Cancer stem cells (CSC's) have emerged as a key area of investigation due to associations with cancer development and treatment resistance, related to their ability to remain quiescent, self-renew and terminally differentiate. Targeting CSC's in addition to the tumour bulk could ensure complete removal of the cancer, lessening the risk of relapse and improving patient survival. Understanding the mechanisms supporting the functions of CSC's is essential to highlight targets for the development of therapeutic strategies. Changes in intracellular calcium through calcium channel activity is fundamental for integral cellular processes such as proliferation, migration, differentiation and survival in a range of cell types, under both normal and pathological conditions. Here in we highlight how calcium channels represent a key mechanism involved in CSC function. It is clear that expression and or function of a number of channels involved in calcium entry and intracellular store release are altered in CSC's. Correlating with aberrant proliferation, self-renewal and differentiation, which in turn promoted cancer progression and treatment resistance. Research outlined has demonstrated that targeting altered calcium channels in CSC populations can reduce their stem properties and induce terminal differentiation, sensitising them to existing cancer treatments. Overall this highlights calcium channels as emerging novel targets for CSC therapies.

Neuroprotective effect of Apelin 13 on ischemic stroke by activating AMPK/GSK-3β/Nrf2 signaling

Background

Previous studies had showed that Apelin 13 could protect against apoptosis induced by ischemic/reperfusion (I/R). However, the mechanisms whereby Apelin 13 protected brain I/R remained to be elucidated. The present study was designed to determine whether Apelin 13 provided protection through AMPK/GSK-3β/Nrf2 pathway.

Methods

In vivo, the I/R model was induced and Apelin 13 was given intracerebroventricularly 15 min before reperfusion. The neurobehavioral scores, infarction volumes, and some cytokines in the brain were measured. For in vitro study, PC12 cells were used. To clarify the mechanisms, proteases inhibitors or siRNA were used. Protein levels were investigated by western blotting.

Results

The results showed that Apelin 13 treatment significantly reduced infarct size, improved neurological outcomes, decreased brain edema, and inhibited cell apoptosis, oxidative stress, and neuroinflammation after I/R. Apelin 13 significantly increased the expression of Nrf2 and the phosphorylation levels of AMPK and GSK-3β. Furthermore, in cultured PC12 cells, the same protective effects were also observed. Silencing Nrf2 gene with its siRNA abolished the Apelin 13’s prevention of I/R-induced PC12 cell injury, oxidative stress, and inflammation. Inhibition of AMPK by its siRNA decreased the level of Apelin 13-induced Nrf2 expression and diminished the protective effects of Apelin 13. The interplay relationship between GSK-3β and Nrf2 was also verified with relative overexpression. Using selective inhibitors, we further identified the upstream of AMPK/GSK-3β/Nrf2 is AR/Gα/PLC/IP3/CaMKK.

Conclusions

In conclusion, the previous results showed that Apelin 13 protected against I/R-induced ROS-mediated inflammation and oxidative stress through activating the AMPK/GSK-3β pathway by AR/Gα/PLC/IP3/CaMKK signaling, and further upregulated the expression of Nrf2-regulated antioxidant enzymes.

Mechanisms of cardiac ethanol toxicity and novel treatment options

Ethanol can acutely and chronically alter cardiomyocyte and whole-organ function in the heart. Importantly, ethanol acutely and chronically predisposes to arrhythmias, while chronic abuse can induce heart failure. However, the molecular mechanisms of ethanol toxicity in the heart are incompletely understood. In this review, we summarize the current mechanistic knowledge on cardiac ethanol toxicity, with a focus on druggable pathways. Ethanol effects on excitation-contraction coupling, oxidative stress, apoptosis, and cardiac metabolism, as well as effects of ethanol metabolites will be discussed. Important recent findings have been gained by investigation of acute ethanol effects. These include a renewed focus on reactive oxygen species (ROS) and induction of SR Ca²⁺ leak by CaMKII-mediated pathways downstream of ROS. Furthermore, a clinical outlook into potential novel treatment options is provided.

Inhibition of CaMKK2 Enhances Fracture Healing by Stimulating Indian Hedgehog Signaling and Accelerating Endochondral Ossification

Approximately 10% of all bone fractures do not heal, resulting in patient morbidity and healthcare costs. However, no pharmacological treatments are currently available to promote efficient bone healing. Inhibition of Ca2+ /calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) reverses age-associated loss of trabecular and cortical bone volume and strength in mice. In the current study, we investigated the role of CaMKK2 in bone fracture healing and show that its pharmacological inhibition using STO-609 accelerates early cellular and molecular events associated with endochondral ossification, resulting in a more rapid and efficient healing of the fracture. Within 7 days postfracture, treatment with STO-609 resulted in enhanced Indian hedgehog signaling, paired-related homeobox (PRX1)-positive mesenchymal stem cell (MSC) recruitment, and chondrocyte differentiation and hypertrophy, along with elevated expression of osterix, vascular endothelial growth factor, and type 1 collagen at the fracture callus. Early deposition of primary bone by osteoblasts resulted in STO-609-treated mice possessing significantly higher callus bone volume by 14 days following fracture. Subsequent rapid maturation of the bone matrix bestowed fractured bones in STO-609-treated animals with significantly higher torsional strength and stiffness by 28 days postinjury, indicating accelerated healing of the fracture. Previous studies indicate that fixed and closed femoral fractures in the mice take 35 days to fully heal without treatment. Therefore, our data suggest that STO-609 potentiates a 20% acceleration of the bone healing process. Moreover, inhibiting CaMKK2 also imparted higher mechanical strength and stiffness at the contralateral cortical bone within 4 weeks of treatment. Taken together, the data presented here underscore the therapeutic potential of targeting CaMKK2 to promote efficacious and rapid healing of bone fractures and as a mechanism to strengthen normal bones. © 2018 American Society for Bone and Mineral Research.

The effect of HMGB1 on the clinicopathological and prognostic features of non-small cell lung cancer

Several studies have assessed the diagnostic and prognostic values of high mobility group protein box 1 (HMGB1) expression in non-small cell lung cancer (NSCLC), but these results remain controversial. The purpose of this study was to perform a meta-analysis of the gene microarray analyses of datasets from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) to evaluate the association of HMGB1 expression with the clinicopathological and prognostic features of patients with NSCLC. Furthermore, we investigated the underlying molecular mechanisms by bioinformatics analysis. Twenty relevant articles involving 2651 patients were included in this meta-analysis; the HMGB1 expression in NSCLC tissues was significantly higher than that in the healthy non-cancer control tissues. We also found an indication by microarray analysis and meta-analysis that HMGB1 expression was associated with the cancer TNM Staging System. In terms of prognostic features, a survival analysis from KM-Plotter tool revealed that the high HMGB1 expression group exhibited poorer survival in lung adenocarcinoma (ADC) and overall NSCLC patients. The survival and disease-free analyses from TCGA datasets also showed that HMGB1 mainly affected the development of patients with ADC. Therefore, we focused on how HMGB1 affected the prognosis and development of ADC using bioinformatics analyses and detected that the mitogen-activated protein kinases (MAPK), apoptosis and cell cycle signaling pathways were the key pathways that varied during HMGB1 up-regulation in ADC. Moreover, various genes such as PLCG2, the phosphatidylinositol-4, 5-bisphosphate 3-kinase superfamily (PI3Ks), protein kinase C (PKC) and DGKZ were selected as hub genes in the gene regulatory network. Our results indicated that HMGB1 is a potential biomarker to predict progression and survival of NSCLC, especially of ADC types.

Functional Analyses of RUNX3 and CaMKIINα in Ovarian Cancer Cell Lines Reveal Tumor-Suppressive Functions for CaMKIINα and Dichotomous Roles for RUNX3 Transcript Variants

(1) Background: Epithelial ovarian cancer (EOC) is the most lethal cancer of the female reproductive system. In an earlier study, we identified multiple genes as hypermethylated in tumors of patients with poor prognosis. The most promising combination of markers to predict a patient’s outcome was CaMKIINα and RUNX3. Aim of this study was to functionally validate the importance of both genes. (2) Methods: IC₅₀ measurements, cell cycle distribution-, proliferation, and migration experiments were conducted after transgene overexpression in two EOC cell lines. (3) Results: We showed that CaMKIINα has tumor suppressive functions in vitro and reduces proliferation, migration, and colony formation. However, it had no effect on the reversion of the resistance to cisplatin. RUNX3 exhibited dualistic functions related to cisplatin sensitivity and migration capacity, depending on the respective transcript variant (TV). A2780 cells expressing RUNX3 TV2—the promoter of which harbors a CpG (5′-C-phosphate-G-3′) island and is potentially inactivated by hypermethylation—exhibited increased cisplatin sensitivity and reduced migration properties. However, RUNX3 TV1, not affected by CpG island methylation could be characterized as mediating resistance and enhancing migration in A2780. The higher resistance of RUNX3 TV1 transfected cells correlates with a reduction of cell proliferation. Moreover, RUNX3 TV1 expressing cells exhibit a reduced cell cycle arrest at the gap-2 or mitosis phase (G2/M) under cisplatin treatment comparable to resistant A2780 subcultures. (4) Conclusion: It appears that CaMKIINα and RUNX3 TV2 can reduce the malignant potential of EOC cells.

Androgen Receptor-CaMKK2 Axis in Prostate Cancer and Bone Microenvironment

The skeletal system is of paramount importance in advanced stage prostate cancer (PCa) as it is the preferred site of metastasis. Complex mechanisms are employed sequentially by PCa cells to home to and colonize the bone. Bone-resident PCa cells then recruit osteoblasts (OBs), osteoclasts (OCs), and macrophages within the niche into entities that promote cancer cell growth and survival. Since PCa is heavily reliant on androgens for growth and survival, androgen-deprivation therapy (ADT) is the standard of care for advanced disease. Although it significantly improves survival rates, ADT detrimentally affects bone health and significantly increases the risk of fractures. Moreover, whereas the majority patients with advanced PCa respond favorably to androgen deprivation, most experience a relapse of the disease to a hormone-refractory form within 1-2 years of ADT. The tumor adapts to surviving under low testosterone conditions by selecting for mutations in the androgen receptor (AR) that constitutively activate it. Thus, AR signaling remains active in PCa cells and aids in its survival under low levels of circulating androgens and additionally allows the cancer cells to manipulate the bone microenvironment to fuel its growth. Hence, AR and its downstream effectors are attractive targets for therapeutic interventions against PCa. Ca²⁺/calmodulin-dependent protein kinase kinase 2 (CaMKK2), was recently identified as a key downstream target of AR in coordinating PCa cell growth, survival, and migration. Additionally, this multifunctional serine/threonine protein kinase is a critical mediator of bone remodeling and macrophage function, thus emerging as an attractive therapeutic target downstream of AR in controlling metastatic PCa and preventing ADT-induced bone loss. Here, we discuss the role played by AR-CaMKK2 signaling axis in PCa survival, metabolism, cell growth, and migration as well as the cell-intrinsic roles of CaMKK2 in OBs, OCs, and macrophages within the bone microenvironment.

Calcineurin/P-ERK/Egr-1 Pathway is Involved in Fear Memory Impairment after Isoflurane Exposure in Mice

Isoflurane exposure adversely influences subsequent fear memory formation in mice. Calcineurin (CaN), a phosphatase, prevents the establishment of emotional memory by dephosphorylating substrates and inhibiting the expression of learning and memory related genes. We investigated whether isoflurane impairment of fear memory formation was associated with altered CaN activity and downstream phosphorylated-extracellular signal-regulated kinases (p-ERK) and early growth response gene-1 (Egr-1) expression in hippocampus and amygdala. We also tested whether memory performance can be rescued by the CaN inhibitor FK506. Adult C57BL/6 mice were injected FK506 or vehicle after being exposed to 1.3% isoflurane or air for 1 h. After a 1 h- recovery, mice underwent classical fear conditioning (FC) training. Fear memory were tested 30 min, 48 h and 7 days after training. The activity of CaN, and expression of p-ERK and Egr-1 in hippocampus and amygdala were analyzed. Isoflurane exposure reduced mice freezing time in contextual and tone FC tests 30 min and 48 h after training. Hippocampus and amygdala from isoflurane-exposed mice had enhanced CaN activity, reduced p-ERK/ERK and Egr-1 expression. All these changes in isoflurane-exposed mice were attenuated by FK506 treatment. These results indicate calcineurin/p-ERK/Egr-1 Pathway is involved in fear memory impairment after isoflurane exposure in mice.

Stabilization of the c-Myc Protein by CAMKIIγ Promotes T Cell Lymphoma

Although high c-Myc protein expression is observed alongside MYC amplification in some cancers, in most cases protein overexpression occurs in the absence of gene amplification, e.g., T cell lymphoma (TCL). Here, Ca²⁺/calmodulin-dependent protein kinase II γ (CAMKIIγ) was shown to stabilize the c-Myc protein by directly phosphorylating it at serine 62 (S62). Furthermore, CAMKIIγ was shown to be essential for tumor maintenance. Inhibition of CAMKIIγ with a specific inhibitor destabilized c-Myc and reduced tumor burden. Importantly, high CAMKIIγ levels in patient TCL specimens correlate with increased c-Myc and pS62-c-Myc levels. Together, the CAMKIIγ:c-Myc axis critically influences the development and maintenance of TCL and represents a potential therapeutic target for TCL.

Inhibition of the nuclear export of p65 and IQCG in leukemogenesis by NUP98-IQCG

NUP98 fuses with approximately 34 different partner genes via translocation in hematological malignancies. Transgenic or retrovirus-mediated bone marrow transplanted mouse models reveal the leukemogenesis of some NUP98-related fusion genes. We previously reported the fusion protein NUP98-IQ motif containing G (IQCG) in a myeloid/T lymphoid bi-phenoleukemia patient with t(3;11) and confirmed its leukemogenic ability. Herein, we demonstrated the association of NUP98-IQCG with CRM1, and found that NUP98-IQCG expression inhibits the CRM1-mediated nuclear export of p65 and enhances the transcriptional activity of nuclear factor-κB. Moreover, IQCG could be entrapped in the nucleus by NUP98-IQCG, and the fusion protein interacts with calmodulin via the IQ motif in a calcium-independent manner. Therefore, the inhibition of nuclear exports of p65 and IQCG might contribute to the leukemogenesis of NUP98-IQCG.

CaMKK2 Suppresses Muscle Regeneration through the Inhibition of Myoblast Proliferation and Differentiation

Skeletal muscle has a major role in locomotion and muscle disorders are associated with poor regenerative efficiency. Therefore, a deeper understanding of muscle regeneration is needed to provide a new insight for new therapies. CaMKK2 plays a role in the calcium/calmodulin-dependent kinase cascade; however, its role in skeletal muscle remains unknown. Here, we found that CaMKK2 expression levels were altered under physiological and pathological conditions including postnatal myogensis, freeze or cardiotoxin-induced muscle regeneration, and Duchenne muscular dystrophy. Overexpression of CaMKK2 suppressed C2C12 myoblast proliferation and differentiation, while inhibition of CaMKK2 had opposite effect. We also found that CaMKK2 is able to activate AMPK in C2C12 myocytes. Inhibition of AMPK could attenuate the effect of CaMKK2 overexpression, while AMPK agonist could abrogate the effect of CaMKK2 knockdown on C2C12 cell differentiation and proliferation. These results suggest that CaMKK2 functions as an AMPK kinase in muscle cells and AMPK mediates the effect of CaMKK2 on myoblast proliferation and differentiation. Our data also indicate that CaMKK2 might inhibit myoblast proliferation through AMPK-mediated cell cycle arrest by inducing cdc2-Tyr15 phosphorylation and repress differentiation through affecting PGC1α transcription. Lastly, we show that overexpressing CaMKK2 in the muscle of mice via electroporation impaired the muscle regeneration during freeze-induced injury, indicating that CaMKK2 could serve as a potential target to treat patients with muscle injury or myopathies. Together, our study reveals a new role for CaMKK2 as a negative regulator of myoblast differentiation and proliferation and sheds new light on the molecular regulation of muscle regeneration.

Dysregulation of Protein Kinase Gene Expression in NK Cells from Chronic Fatigue Syndrome/Myalgic Encephalomyelitis Patients

BACKGROUND

The etiology and pathomechanism of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) are unknown. However, natural killer (NK) cell dysfunction, in particular reduced NK cytotoxic activity, is a consistent finding in CFS/ME patients. Previous research has reported significant changes in intracellular mitogen-activated protein kinase pathways from isolated NK cells. The purpose of this present investigation was to examine whether protein kinase genes have a role in abnormal NK cell intracellular signaling in CFS/ME.

METHOD

Messenger RNA (mRNA) expression of 528 protein kinase genes in isolated NK cells was analyzed (nCounter GX Human Kinase Kit v2 (XT); NanoString Technologies) from moderate (n = 11; age, 54.9 ± 10.3 years) and severe (n = 12; age, 47.5 ± 8.0 years) CFS/ME patients (classified by the 2011 International Consensus Criteria) and nonfatigued controls (n = 11; age, 50.0 ± 12.3 years).

RESULTS

The expression of 92 protein kinase genes was significantly different in the severe CFS/ME group compared with nonfatigued controls. Among these, 37 genes were significantly upregulated and 55 genes were significantly downregulated in severe CFS/ME patients compared with nonfatigued controls.

CONCLUSIONS

In severe CFS/ME patients, dysfunction in protein kinase genes may contribute to impairments in NK cell intracellular signaling and effector function. Similar changes in protein kinase genes may be present in other cells, potentially contributing to the pathomechanism of this illness.

Aberrant expression and functions of protocadherins in human malignant tumors

Protocadherins (PCDHs) are a group of transmembrane proteins belonging to the cadherin superfamily and are subdivided into "clustered" and "non-clustered" groups. PCDHs vary in both structure and interaction partners and thus regulate multiple biological responses in complex and versatile patterns. Previous researches showed that PCDHs regulated the development of brain and were involved in some neuronal diseases. Recently, studies have revealed aberrant expression of PCDHs in various human malignant tumors. The down-regulation or absence of PCDHs in malignant cells has been associated with cancer progression. Further researches suggest that PCDHs may play major functions as tumor suppressor by inhibiting the proliferation and metastasis of cancer cells. In this review, we focus on the altered expression of PCDHs and their roles in the development of cancer progression. We also discuss the potential mechanisms, by which PCDHs are aberrantly expressed, and its implications in regulating cancers.

Developing and applying the adverse outcome pathway concept for understanding and predicting neurotoxicity

The Adverse Outcome Pathway (AOP) concept has recently been proposed to support a paradigm shift in regulatory toxicology testing and risk assessment. This concept is similar to the Mode of Action (MOA), in that it describes a sequence of measurable key events triggered by a molecular initiating event in which a stressor interacts with a biological target. The resulting cascade of key events includes molecular, cellular, structural and functional changes in biological systems, resulting in a measurable adverse outcome. Thereby, an AOP ideally provides information relevant to chemical structure-activity relationships as a basis for predicting effects of structurally similar compounds. AOPs could potentially also form the basis for qualitative and quantitative predictive modeling of the human adverse outcome resulting from molecular initiating or other key events for which higher-throughput testing methods are available or can be developed. A variety of cellular and molecular processes are known to be critical for normal function of the central (CNS) and peripheral nervous systems (PNS). Because of the biological and functional complexity of the CNS and PNS, it has been challenging to establish causative links and quantitative relationships between key events that comprise the pathways leading from chemical exposure to an adverse outcome in the nervous system. Following introduction of the principles of MOA and AOPs, examples of potential or putative adverse outcome pathways specific for developmental or adult neurotoxicity are summarized and aspects of their assessment considered. Their possible application in developing mechanistically informed Integrated Approaches to Testing and Assessment (IATA) is also discussed.

Overexpression of TRPV3 Correlates with Tumor Progression in Non-Small Cell Lung Cancer

(1) BACKGROUND: Transient receptor potential vanilloid 3 (TRPV3) is a member of the TRP channels family of Ca(2+)-permeant channels. The proteins of some TRP channels are highly expressed in cancer cells. This study aimed to assess the clinical significance and biological functions of TRPV3 in non-small cell lung cancer (NSCLC); (2) METHODS: Immunohistochemistry was used to detect the expression of TRPV3 in NSCLC tissues and adjacent noncancerous lung tissues. Western blot was used to detect the protein expressions of TRPV3, CaMKII, p-CaMKII, CyclinA, CyclinD, CyclinE1, CDK2, CDK4, and P27. Small interfering RNA was used to deplete TRPV3 expression. A laser scanning confocal microscope was used to measure intracellular calcium concentration ([Ca(2+)]i). Flow cytometry was used to analyze cell cycle; (3) RESULTS: TRPV3 was overexpressed in 65 of 96 (67.7%) human lung cancer cases and correlated with differentiation (p = 0.001) and TNM stage (p = 0.004). Importantly, TRPV3 expression was associated with short overall survival. In addition, blocking or knockdown of TRPV3 could inhibit lung cancer cell proliferation. Moreover, TRPV3 inhibition could decrease [Ca(2+)]i of lung cancer cells and arrest cell cycle at the G1/S boundary. Further results revealed that TRPV3 inhibition decreased expressions of p-CaMKII, CyclinA, CyclinD1, CyclinE, and increased P27 level; (4) CONCLUSIONS: Our findings demonstrate that TRPV3 was overexpressed in NSCLC and correlated with lung cancer progression. TRPV3 activation could promote proliferation of lung cancer cells. TRPV3 might serve as a potential companion drug target in NSCLC.

Stromal Expression of miR-143/145 Promotes Neoangiogenesis in Lung Cancer Development

The two unrelated miRNAs miR-143 and miR-145, coexpressed from the miR-143/145 cluster, have been proposed to act as tumor suppressors in human cancer, and therapeutic benefits of delivering miR-143 and miR-145 to tumors have been reported. In contrast, we found that tumor-specific deletion of miR-143/145 in an autochthonous mouse model of lung adenocarcinoma did not affect tumor development. This was consistent with the lack of endogenous miR-143/145 expression in normal and transformed lung epithelium. Surprisingly, miR-143/145 in the tumor microenvironment dramatically promoted tumor growth by stimulating the proliferation of endothelial cells. Loss of miR-143/145 in vivo led to derepression of the miR-145 target CAMK1D, an inhibitory kinase, which when overexpressed prevents mitotic entry of endothelial cells. As a consequence, tumors in miR-143/145-deficient animals exhibited diminished neoangiogenesis, increased apoptosis, and their expansion was limited by the tumor's ability to co-opt the alveolar vasculature. These findings demonstrate that stromal miR-143/145 promotes tumorigenesis and caution against the use of these miRNAs as agents in cancer therapeutics.

SIGNIFICANCE

This study shows that miR-143/145 expressed from the tumor microenvironment stimulates neoangiogenesis and supports tumor expansion in the lung, demonstrating a surprising role for the putative tumor suppressor miRNA cluster in promoting tumorigenesis. We propose inhibition of miR-143/145 as a therapeutic avenue to modulate tumor neoangiogenesis.

Thrombin/Matrix Metalloproteinase-9-Dependent SK-N-SH Cell Migration is Mediated Through a PLC/PKC/MAPKs/NF-κB Cascade

Thrombin has been known to activate inflammatory genes including matrix metalloproteinases (MMPs). The elevated expression of MMP-9 has been observed in patients with neuroinflammatory diseases and may contribute to the pathology of brain diseases. However, the mechanisms underlying thrombin-induced MMP-9 expression in SK-N-SH cells remain unknown. The effects of thrombin on MMP-9 expression were examined in SK-N-SH cells by gelatin zymography, Western blot, real-time PCR, promoter activity assay, and cell migration assay. The detailed mechanisms were analyzed by using pharmacological inhibitors and small intefering RNA (siRNA) transfection. Here, we demonstrated that thrombin induced the expression of proform MMP-9 and migration of SK-N-SH cells, which were attenuated by pretreatment with the inhibitor of thrombin (PPACK), Gq (GPA2A), PC-PLC (D609), PI-PLC (ET-18-OCH₃), nonselective protien kinase C (PKC, GF109203X), PKCα/βII (Gö6983), PKCδ (Rottlerin), p38 mitogen-activated protein kinases (MAPK) (SB202190), JNK1/2 (SP600125), or NF-κB (Bay11-7082 or Helenalin) and transfection with siRNA of Gq, PKCα, PKCβ, PKCδ, p38, JNK1/2, IKKα, IKKβ, or p65. Moreover, thrombin-stimulated PKCα/βII, PKCδ, p38 MAPK, JNK1/2, or p65 phosphorylation was abrogated by their respective inhibitor of PPACK, GPA2A, D609, ET-18-OCH₃, Gö6983, Rottlerin, SB202190, SP600125, Bay11-7082, or Helenalin. Pretreatment with these inhibitors or transfection with MMP-9 siRNA also blocked thrombin-induced SK-N-SH cell migration. Our results show that thrombin stimulates a Gq/PLC/PKCs/p38 MAPK and JNK1/2 cascade, which in turn triggers NF-κB activation and ultimately induces MMP-9 expression and cell migration in SK-N-SH cells.

A genetic variant in CAMKK2 gene is possibly associated with increased risk of bipolar disorder

A recent large-scale study have reported that rs1063843, a single nucleotide polymorphism located in the CAMKK2 gene is highly associated with schizophrenia in European and Han Chinese populations. Increasing evidences show that schizophrenia and bipolar disorder have some common genetic variance. Here, we evaluated the association of this variant with schizophrenia and bipolar disorder in Iranian population. Genomic DNA was extracted from peripheral blood of 500 schizophrenic patients, 500 bipolar patients and 500 normal controls and all were genotyped for the rs1063843 using a PCR-RFLP method. The allele frequency of rs1063843 was significantly different in both schizophrenia and bipolar patients comparing to control group. For the first time, we showed that rs1063843 is highly associated with bipolar disorder, although more replication studies are needed to confirm our findings. Our results also support the findings of previous studies suggesting a significant association between rs1063843 and schizophrenia.

Evolutionary and functional perspectives on signaling from neuronal surface to nucleus

Reliance on Ca(2+) signaling has been well-preserved through the course of evolution. While the complexity of Ca(2+) signaling pathways has increased, activation of transcription factors including CREB by Ca(2+)/CaM-dependent kinases (CaMKs) has remained critical for long-term plasticity. In C. elegans, the CaMK family is made up of only three members, and CREB phosphorylation is mediated by CMK-1, the homologue of CaMKI. CMK-1 nuclear translocation directly regulates adaptation of thermotaxis behavior in response to changes in the environment. In mammals, the CaMK family has been expanded from three to ten members, enabling specialization of individual elements of a signal transduction pathway and increased reliance on the CaMKII subfamily. This increased complexity enables private line communication between Ca(2+) sources at the cell surface and specific cellular targets. Using both new and previously published data, we review the mechanism of a γCaMKII-CaM nuclear translocation. This intricate pathway depends on a specific role for multiple Ca(2+)/CaM-dependent kinases and phosphatases: α/βCaMKII phosphorylates γCaMKII to trap CaM; CaN dephosphorylates γCaMKII to dispatch it to the nucleus; and PP2A induces CaM release from γCaMKII so that CaMKK and CaMKIV can trigger CREB phosphorylation. Thus, while certain basic elements have been conserved from C. elegans, evolutionary modifications offer opportunities for targeted communication, regulation of key nodes and checkpoints, and greater specificity and flexibility in signaling.

Is the Pharmacological Mode of Action of Chromium(III) as a Second Messenger?

Although recent studies have shown that chromium (as the trivalent ion) is not an essential trace element, it has been demonstrated to generate beneficial effects at pharmacologically relevant doses on insulin sensitivity and cholesterol levels of rodent models of insulin insensitivity, including models of type 2 diabetes. The mode of action of Cr(III) at a molecular level is still an area of active debate; however, the movement of Cr(III) in the body, particularly in response to changes in insulin concentration, suggests that Cr(III) could act as a second messenger, amplifying insulin signaling. The evidence for the pharmacological mechanism of Cr(III)'s ability to increase insulin sensitivity by acting as a second messenger is reviewed, and proposals for testing this hypothesis are described.

Functional genomics identifies novel genes essential for clear cell renal cell carcinoma tumor cell proliferation and migration

Currently there is a lack of targeted therapies that lead to long-term attenuation or regression of disease in patients with advanced clear cell renal cell carcinoma (ccRCC). Our group has implemented a high-throughput genetic analysis coupled with a high-throughput proliferative screen in order to investigate the genetic contributions of a large cohort of overexpressed genes at the functional level in an effort to better understand factors involved in tumor initiation and progression.

Patient gene array analysis identified transcripts that are consistently elevated in patient ccRCC as compared to matched normal renal tissues. This was followed by a high-throughput lentivirus screen, independently targeting 195 overexpressed transcripts identified in the gene array in four ccRCC cell lines. This revealed 31 ‘hits’ that contribute to ccRCC cell proliferation.

Many of the hits identified are not only presented in the context of ccRCC for the first time, but several have not been previously linked to cancer. We further characterize the function of a group of hits in tumor cell invasion. Taken together these findings reveal pathways that may be critical in ccRCC tumorigenicity, and identifies novel candidate factors that could serve as targets for therapeutic intervention or diagnostic/prognostic biomarkers for patients with advanced ccRCC.

Inhibition of CaMKK2 reverses age-associated decline in bone mass

Decline in bone formation is a major contributing factor to the loss of bone mass associated with aging. We previously showed that the genetic ablation of the tissue-restricted and multifunctional Ca(2+)/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) stimulates trabecular bone mass accrual, mainly by promoting anabolic pathways and inhibiting catabolic pathways of bone remodeling. In this study, we investigated whether inhibition of this kinase using its selective cell-permeable inhibitor STO-609 will stimulate bone formation in 32 week old male WT mice and reverse age-associated of decline in bone volume and strength. Tri-weekly intraperitoneal injections of saline or STO-609 (10 μM) were performed for six weeks followed by metabolic labeling with calcein and alizarin red. New bone formation was assessed by dynamic histomorphometry whereas micro-computed tomography was employed to measure trabecular bone volume, microarchitecture and femoral mid-shaft geometry. Cortical and trabecular bone biomechanical properties were assessed using three-point bending and punch compression methods respectively. Our results reveal that as they progress from 12 to 32 weeks of age, WT mice sustain a significant decline in trabecular bone volume, microarchitecture and strength as well as cortical bone strength. However, treatment of the 32 week old WT mice with STO-609 stimulated apposition of new bone and completely reversed the age-associated decrease in bone volume, quality, as well as trabecular and cortical bone strength. We also observed that regardless of age, male Camkk2(-/-) mice possessed significantly elevated trabecular bone volume, microarchitecture and compressive strength as well as cortical bone strength compared to age-matched WT mice, implying that the chronic loss of this kinase attenuates age-associated decline in bone mass. Further, whereas STO-609 treatment and/or the absence of CaMKK2 significantly enhanced the femoral mid-shaft geometry, the mid-shaft cortical wall thickness and material bending stress remained similar among the cohorts, implying that regardless of treatment, the material properties of the bone remain similar. Thus, our cumulative results provide evidence for the pharmacological inhibition of CaMKK2 as a bone anabolic strategy in combating age-associated osteoporosis.

The central nervous system transcriptome of the weakly electric brown ghost knifefish (Apteronotus leptorhynchus): de novo assembly, annotation, and proteomics validation

Background

The brown ghost knifefish (Apteronotus leptorhynchus) is a weakly electric teleost fish of particular interest as a versatile model system for a variety of research areas in neuroscience and biology. The comprehensive information available on the neurophysiology and neuroanatomy of this organism has enabled significant advances in such areas as the study of the neural basis of behavior, the development of adult-born neurons in the central nervous system and their involvement in the regeneration of nervous tissue, as well as brain aging and senescence. Despite substantial scientific interest in this species, no genomic resources are currently available.

Results

Here, we report the de novo assembly and annotation of the A. leptorhynchus transcriptome. After evaluating several trimming and transcript reconstruction strategies, de novo assembly using Trinity uncovered 42,459 unique contigs containing at least a partial protein-coding sequence based on alignment to a reference set of known Actinopterygii sequences. As many as 11,847 of these contigs contained full or near-full length protein sequences, providing broad coverage of the proteome. A variety of non-coding RNA sequences were also identified and annotated, including conserved long intergenic non-coding RNA and other long non-coding RNA observed previously to be expressed in adult zebrafish (Danio rerio) brain, as well as a variety of miRNA, snRNA, and snoRNA. Shotgun proteomics confirmed translation of open reading frames from over 2,000 transcripts, including alternative splice variants. Assignment of tandem mass spectra was greatly improved by use of the assembly compared to databases of sequences from closely related organisms. The assembly and raw reads have been deposited at DDBJ/EMBL/GenBank under the accession number GBKR00000000. Tandem mass spectrometry data is available via ProteomeXchange with identifier PXD001285.

Conclusions

Presented here is the first release of an annotated de novo transcriptome assembly from Apteronotus leptorhynchus, providing a broad overview of RNA expressed in central nervous system tissue. The assembly, which includes substantial coverage of a wide variety of both protein coding and non-coding transcripts, will allow the development of better tools to understand the mechanisms underlying unique characteristics of the knifefish model system, such as their tremendous regenerative capacity and negligible brain senescence.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1354-2) contains supplementary material, which is available to authorized users.

Serum containing Tongqiaohuoxue decoction suppresses glutamate-induced PC12 cell injury

Glutamate application is an established method of inducing PC12 cell injury. PC12 cells were cultured with serum containing Tongqiaohuoxue decoction consisting of moschus, Carthamus tinctorius, Rhizoma chuanxiong, Semen pruni persicae, and Radix Paeoniae Rubra. After 24 hours of co-cultivation, glutamate (12.5 mM) was added to the culture medium. We found that serum containing Tongqiaohuoxue decoction prevented the increase in reactive oxygen species, and the decreases in superoxide dismutase and Na⁺-K⁺-ATPase activity, induced by glutamate. It also reduced the concentration of malondialdehyde, enhanced the mitochondrial transmembrane potential, inhibited the elevation of cellular calcium, and decreased phosphorylation of calmodulin-dependent protein kinase II. Thus, serum containing Tongqiaohuoxue decoction had protective effects on cell proliferation and membrane permeability in glutamate-injured PC12 cells.

Dengue and calcium

Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium has been also implicated in the immuopathogenesis of dengue; however, the precise clinical implications of these interactions are yet not clearly defined. Derangements of calcium homeostasis are likely to be associated with myocardial dysfunction and cardiac arrhythmias observed in dengue as suggested by in vitro studies. Calcium also plays a role in platelet aggregation. Studies evaluating the therapeutic use of calcium in dengue have been underpowered and poorly designed to make any firm recommendations. Further studies are needed to explore the role and usefulness of maintenance of calcium homeostasis in modulating cardiac dysfunction, immunopathogenesis, and platelet abnormalities related to dengue.

CaMKII is essential for the cellular clock and coupling between morning and evening behavioral rhythms

Daily behavioral rhythms in mammals are governed by the central circadian clock located in the suprachiasmatic nucleus (SCN), and calcium is thought to play a role in the oscillation of the SCN. Kon et al. now find that Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) activity promotes dimerization of CLOCK and BMAL1 and is essential for the cellular oscillation and synchronization among oscillators in the SCN. Kinase-dead CaMKIIα weakened the behavioral rhythmicity and elicited decoupling between the morning and evening activity rhythms.

Daily behavioral rhythms in mammals are governed by the central circadian clock, located in the suprachiasmatic nucleus (SCN). The behavioral rhythms persist even in constant darkness, with a stable activity time due to coupling between two oscillators that determine the morning and evening activities. Accumulating evidence supports a prerequisite role for Ca²⁺ in the robust oscillation of the SCN, yet the underlying molecular mechanism remains elusive. Here, we show that Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) activity is essential for not only the cellular oscillation but also synchronization among oscillators in the SCN. A kinase-dead mutation in mouse CaMKIIα weakened the behavioral rhythmicity and elicited decoupling between the morning and evening activity rhythms, sometimes causing arrhythmicity. In the mutant SCN, the right and left nuclei showed uncoupled oscillations. Cellular and biochemical analyses revealed that Ca²⁺–calmodulin–CaMKII signaling contributes to activation of E-box-dependent gene expression through promoting dimerization of circadian locomotor output cycles kaput (CLOCK) and brain and muscle Arnt-like protein 1 (BMAL1). These results demonstrate a dual role of CaMKII as a component of cell-autonomous clockwork and as a synchronizer integrating circadian behavioral activities.

The many faces of calmodulin in cell proliferation, programmed cell death, autophagy, and cancer

Calmodulin (CaM) is a ubiquitous Ca(2+) receptor protein mediating a large number of signaling processes in all eukaryotic cells. CaM plays a central role in regulating a myriad of cellular functions via interaction with multiple target proteins. This review focuses on the action of CaM and CaM-dependent signaling systems in the control of vertebrate cell proliferation, programmed cell death and autophagy. The significance of CaM and interconnected CaM-regulated systems for the physiology of cancer cells including tumor stem cells, and processes required for tumor progression such as growth, tumor-associated angiogenesis and metastasis are highlighted. Furthermore, the potential targeting of CaM-dependent signaling processes for therapeutic use is discussed.

Regulation of connexin- and pannexin-based channels by post-translational modifications

Connexin (Cx) and pannexin (Panx) proteins form large conductance channels, which function as regulators of communication between neighbouring cells via gap junctions and/or hemichannels. Intercellular communication is essential to coordinate cellular responses in tissues and organs, thereby fulfilling an essential role in the spreading of signalling, survival and death processes. The functional properties of gap junctions and hemichannels are modulated by different physiological and pathophysiological stimuli. At the molecular level, Cxs and Panxs function as multi-protein channel complexes, regulating their channel localisation and activity. In addition to this, gap junctional channels and hemichannels are modulated by different post-translational modifications (PTMs), including phosphorylation, glycosylation, proteolysis, N-acetylation, S-nitrosylation, ubiquitination, lipidation, hydroxylation, methylation and deamidation. These PTMs influence almost all aspects of communicating junctional channels in normal cell biology and pathophysiology. In this review, we will provide a systematic overview of PTMs of communicating junction proteins and discuss their effects on Cx and Panx-channel activity and localisation.

Inhibition of Ca²⁺/calmodulin-dependent protein kinase kinase 2 stimulates osteoblast formation and inhibits osteoclast differentiation

Bone remodeling, a physiological process characterized by bone formation by osteoblasts (OBs) and resorption of preexisting bone matrix by osteoclasts (OCs), is vital for the maintenance of healthy bone tissue in adult humans. Imbalances in this vital process result in pathological conditions including osteoporosis. Owing to its initial asymptomatic nature, osteoporosis is often detected only after the patient has sustained significant bone loss or a fracture. Hence, anabolic therapeutics that stimulate bone accrual is in high clinical demand. Here we identify Ca²⁺/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) as a potential target for such therapeutics because its inhibition enhances OB differentiation and bone growth and suppresses OC differentiation. Mice null for CaMKK2 possess higher trabecular bone mass in their long bones, along with significantly more OBs and fewer multinuclear OCs. In vitro, although Camkk2⁻/⁻ mesenchymal stem cells (MSCs) yield significantly higher numbers of OBs, bone marrow cells from Camkk2⁻/⁻ mice produce fewer multinuclear OCs. Acute inhibition of CaMKK2 by its selective, cell-permeable pharmacological inhibitor STO-609 also results in increased OB and diminished OC formation. Further, we find phospho-protein kinase A (PKA) and Ser¹³³ phosphorylated form of cyclic adenosine monophosphate (cAMP) response element binding protein (pCREB) to be markedly elevated in OB progenitors deficient in CaMKK2. On the other hand, genetic ablation of CaMKK2 or its pharmacological inhibition in OC progenitors results in reduced pCREB as well as significantly reduced levels of its transcriptional target, nuclear factor of activated T cells, cytoplasmic (NFATc1). Moreover, in vivo administration of STO-609 results in increased OBs and diminished OCs, conferring significant protection from ovariectomy (OVX)-induced osteoporosis in adult mice. Overall, our findings reveal a novel function for CaMKK2 in bone remodeling and highlight the potential for its therapeutic inhibition as a valuable bone anabolic strategy that also inhibits OC differentiation in the treatment of osteoporosis.

Further delineation of genotype-phenotype correlation in homozygous 2p21 deletion syndromes: first description of patients without cystinuria

Homozygous contiguous gene deletion syndromes are rare. On 2p21, however, several overlapping homozygous gene deletion syndromes have been described, all presenting with cystinuria but otherwise distinct phenotypes. Hypotonia-cystinuria syndrome (HCS, OMIM606407) is characterized by infantile hypotonia, poor feeding, and growth hormone deficiency. Affected individuals carry homozygous deletions including the cystinuria gene SLC3A1 and the adjacent PREPL gene. Larger homozygous deletions in this region encompassing the PPM1B, SLC3A1, PREPL, and C2orf34 (CAMKMT) genes result in a more severe phenotype, the 2p21 deletion syndrome. A phenotype intermediate to HCS and the 2p21 deletion syndrome is termed atypical HCS and is caused by deletion of SLC3A1, PREPL, and C2orf34 (CAMKMT). Using high resolution SNP array molecular karyotyping we identified two siblings with a homozygous deletion of 83 kb partially encompassing the genes PREPL and C2orf34 (CAMKMT), but not the SLC3A1 gene. The affected siblings display a recognizable phenotype which is similar to atypical HCS with regard to growth failure and neuro-muscular features, but is characterized by lack of cystinuria. The patients also exhibit features which have not been reported to date such as cleft palate and genital abnormalities. In conclusion, we report the first patients with a homozygous 2p21 deletion syndrome without cystinuria and further delineate the complex genotype-phenotype correlations of homozygous microdeletion syndromes of this region.

Involvement of CaMKIV in neurogenic effect with chronic fluoxetine treatment

Calcium-calmodulin dependent protein kinase IV (CaMKIV) is a protein kinase that has been suggested to participate in fluoxetine (FLX)-induced phosphorylation of cyclic AMP-response element binding protein (CREB). CREB is a key transcription factor in adult neurogenesis. The present study aimed at evaluating whether CaMKIV is involved in adult hippocampal neurogenesis with FLX treatment. Effects of chronic FLX on hippocampal cell proliferation, survival and phenotypes were assessed using bromodeoxyuridine (BrdU) immunohistochemistry or BrdU/neuronal nuclei (NeuN)/S100β immunofluorescence staining in wild-type (WT) and CaMKIV knockout (KO) mice. Expression and phosphorylation of CaMKIV and CREB were assessed using RT-PCR and Western blotting. The behavioural action with FLX was assessed in the novelty suppressed feeding test (NSF), which is considered neurogenesis-dependent. CaMKIV KO mice have reduced cell proliferation, but not survival in the dentate gyrus of hippocampus with chronic treatment of FLX when compared to wild littermates. Phenotype analysis showed that most newborn cells matured into neurons. Phosphorylation of CaMKIV was up-regulated in WT mice and phosphorylation of CREB was impaired in CaMKIV KO mice after FLX treatment. The behavioural effects of FLX in NSF were similar in both types. These data suggest that CaMKIV is involved in some aspects of FLX-promoting hippocampal neurogenesis.

Insulin-like growth factor binding proteins increase intracellular calcium levels in two different cell lines

Background

Insulin-like growth factor binding proteins (IGFBPs) are six related secreted proteins that share IGF-dependent and -independent functions. If the former functions begin to be well described, the latter are somewhat more difficult to investigate and to characterize. At the cellular level, IGFBPs were shown to modulate numerous processes including cell growth, differentiation and apoptosis. However, the molecular mechanisms implicated remain largely unknown. We previously demonstrated that IGFBP-3, but not IGFBP-1 or IGFBP-5, increase intracellular calcium concentration in MCF-7 cells (Ricort J-M et al. (2002) FEBS lett 527: 293–297).

Methodology/Principal Findings

We perform a global analysis in which we studied, by two different approaches, the binding of each IGFBP isoform (i.e., IGFBP-1 to -6) to the surface of two different cellular models, MCF-7 breast adenocarcinoma cells and C2 myoblast proliferative cells, as well as the IGFBP-induced increase of intracellular calcium concentration. Using both confocal fluorescence microscopy and flow cytometry analysis, we showed that all IGFBPs bind to MCF-7 cell surface. By contrast, only four IGFBPs can bind to C2 cell surface since neither IGFBP-2 nor IGFBP-4 were detected. Among the six IGFBPs tested, only IGFBP-1 did not increased intracellular calcium concentration whatever the cellular model studied. By contrast, IGFBP-2, -3, -4 and -6, in MCF-7 cells, and IGFBP-3, -5 and -6, in C2 proliferative cells, induce a rapid and transient increase in intracellular free calcium concentration. Moreover, IGFBP-2 and -3 (in MCF-7 cells) and IGFBP-5 (in C2 cells) increase intracellular free calcium concentration by a pertussis toxin sensitive signaling pathway.

Conclusions

Our results demonstrate that IGFBPs are able to bind to cell surface and increase intracellular calcium concentration. By characterizing the IGFBPs-induced cell responses and intracellular couplings, we highlight the cellular specificity and complexity of the IGF-independent actions of these IGF binding proteins.

Differential load-regulated global gene expression in mouse trabecular osteocytes

Osteocytes are considered the skeletal mechanosensors. However, because osteocytes, particularly trabecular, are barely accessible to in vivo molecular analyses, very little is known on the signals transmitted by these cells to the extra-trabecular milieu. To investigate so called "osteocytic genes" involved in extracellular signaling, we have used a recently developed model whereby a single caudal mouse vertebra (C5) is subjected to controlled compression loading and further devised a method for the isolation of high quality RNA from trabecular osteocytes. RNA samples from loaded and sham-loaded individual vertebrae where then subjected to gene array analysis following the administration of a single or repetitive loading doses (thrice weekly for 4 weeks). Focusing on extracellular genes potentially involved in mediating osteocyte-derived signals to the trabecular surface, we identified sets of genes differentially regulated by either single or multiple loading bouts as well as genes affected by both loading protocols. A comparison with published studies on load-regulated genes in cortical osteocytes revealed that the majority of these genes are specifically activated/silenced in the trabecular bone. Many of these genes could be clustered according to processes directly relevant to the life cycle and activity of osteoblasts and osteoclasts and their progenitors. The present findings are consistent with an osteocytic role in the control of trabecular bone remodeling and mass and provide a comprehensive database of load-regulated genes in trabecular osteocytes that is potentially useful in further mouse genetic studies and identification of drug targets to combat osteoporosis.

Group I metabotropic glutamate receptor-mediated gene transcription and implications for synaptic plasticity and diseases

Stimulation of group I metabotropic glutamate receptors (mGluRs) initiates a wide variety of signaling pathways. Group I mGluR activation can regulate gene expression at both translational and transcriptional levels, and induces translation or transcription-dependent synaptic plastic changes in neurons. The group I mGluR-mediated translation-dependent neural plasticity has been well reviewed. In this review, we will highlight group I mGluR-induced gene transcription and its role in synaptic plasticity. The signaling pathways (PKA, CaMKs, and MAPKs) which have been shown to link group I mGluRs to gene transcription, the relevant transcription factors (CREB and NF-κB), and target proteins (FMRP and ARC) will be documented. The significance and future direction for characterizing group I mGluR-mediated gene transcription in fragile X syndrome, schizophrenia, drug addiction, and other neurological disorders will also be discussed.