BAFF activates Erk1/2 promoting cell proliferation and survival by Ca2+-CaMKII-dependent inhibition of PP2A in normal and neoplastic B-lymphoid cells

ICAM-1 mediated cell-cell adhesion exerts dual roles on human B cell differentiation and IgG production

Intercellular adhesion molecule 1 (ICAM-1) plays prominent roles in mediating cell-cell adhesion which also facilitates B cell activation and differentiation with the help from CD4+ T cells. Here, we have reported a unique phenomenon that increased ICAM-1 on purified human CD4+ T cells upon anti-CD3/CD28 stimulation enhanced CD4+ T-B cell adhesion whereas induced less B cell differentiation and IgG production. This was largely due to increased PD-1 expression on CD19hi B cells after coculturing with hyperactivated CD4+ T cells. Consequently, ICAM-1 blockade during CD4+ T cell-B cell coculture promoted IgG production with the activation of ERK1/2 and Blimp-1/IRF4 upregulation. Consistently, CD4+ T cells from moderate-to-severe SLE patients with high ICAM-1 expression mediated less IgG production after T-B coculture. Therefore, ICAM-1-mediated human CD4+ T-B cell adhesion provides dual roles on B cell differentiation and IgG production partially depending on expression levels of PD-1 on B cells, supporting cell adhesion and subsequent PD-1 induction as an alternative intrinsic checkpoint for B cell differentiation.

Intermedin (adrenomedullin 2) plays a protective role in sepsis by regulating T- and B-cell proliferation and activity

BACKGROUND

Sepsis is the major cause of death in intensive care units. We previously found that intermedin (IMD), a calcitonin family peptide, can protect against sepsis by dynamically repairing vascular endothelial junctions and can ameliorate the inflammatory response by inhibiting the infiltration of macrophages in peripheral tissues. The effects of IMD on inflammatory and immune responses indicate that IMD may play a role in immunity. However, whether IMD affects immune cell development, differentiation and response to infection remains unclear.

METHODS

IMD-knockout (Adm2-/-) mice were generated in our previous work. Wild-type and IMD-KO mice were subjected to sham or cecal ligation and puncture (CLP) surgery, and bone marrow cells were obtained for RNA sequencing (RNA-Seq) analysis. The RNA-Seq results were verified by real-time RT-PCR. The effect of IMD KO or IMD rescue on the septic mice was explored using mild and severe infection models induced by CLP surgery at different levels of severity, and the survival outcomes were analyzed using Kaplan-Meier curves and the log-rank test. The mechanism underlying the effects of IMD in T/B cell proliferation and differentiation were investigated by PCR, Western blot (WB), and cell proliferation assays and flow cytometry analysis.

RESULTS

RNA-Seq showed that IMD-KO mice exhibited a primary immunosuppression phenotype characterized by a marked decrease in the expression of T- and B-cell function-related genes. This immunosuppression made the IMD-KO mice vulnerable to pathogenic invasion, and even mild infection killed nearly half of the IMD-KO mice. Supplementation with the IMD peptide restored the expression of T/B-cell-related genes and significantly reduced the mortality rate of the IMD-KO mice. IMD is likely to directly promote T- and B-cell proliferation through ERK1/2 phosphorylation, stimulate T-cell differentiation via Ilr7/Rag1/2-controled T cell receptor (TCR) recombination, and activate B cells via Pax5, a transcription factor that activates at least 170 genes needed for B-cell functions.

CONCLUSION

Together with previous findings, our results indicate that IMD may play a protective role in sepsis via three mechanisms: protecting the vascular endothelium, reducing the inflammatory response, and activating T/B-cell proliferation and differentiation. Our study may provide the first identification of IMD as a calcitonin peptide that plays an important role in the adaptive immune response by activating T/B cells and provides translational opportunities for the design of immunotherapies for sepsis and other diseases associated with primary immunodeficiency.

Immunoglobulin a suppresses B cell receptor-mediated activation of mouse B cells with differential inhibition of signaling molecules

CONTEXT

We previously reported that monoclonal mouse immunoglobulin (Ig) A, OA-4, attenuates sensitization in mice by suppressing B cell activation.

OBJECTIVE

Here, it is demonstrated for the first time that mouse IgA inhibits mouse B cell activation in vitro under natural conditions (i.e. in the absence of chemical, physical, and genetic modifications of IgA and B cells).

MATERIALS AND METHODS

Mouse splenocytes were stimulated with anti-B cell receptor (BCR) antibody or lipopolysaccharide (LPS) in the presence or absence of OA-4. Splenic B cell proliferation and the activation of several intracellular signaling molecules were measured.

RESULTS

Anti-BCR antibody-induced proliferation was markedly inhibited by OA-4 or the commercially available mouse IgA S107, whereas LPS-induced proliferation was weakly attenuated by a high concentration of OA-4. Moreover, OA-4 markedly decreased the anti-BCR antibody-induced phosphorylation of p44/42 mitogen-activated protein kinase (ERK) and CD22 and decreased phosphorylated phospholipase (PLC) γ2 and intracellular Ca²⁺ levels moderately, whereas protein kinase B (Akt) phosphorylation was not affected by OA-4. The MAPK/ERK kinase-ERK and phosphoinositide 3-kinase-Akt pathways were found to play a role in the proliferation of splenocytes induced by anti-BCR antibody based on experiments with their inhibitors. In contrast to that in splenic B cells, ERK phosphorylation induced by anti-BCR antibody in A20 cells was not inhibited by OA-4. The modulatory effects of IgA were different among the cell types and signaling pathways.

CONCLUSION

IgA is a potential immunoregulatory drug utilizing new mechanisms that affect splenic B cells but not A20 lymphomas.

Comparative proteomic analysis provides insight into the key proteins as potential targets underlying the effect of malachite green against Ichthyophthirius multifiliis

Target identification is important for drug discovery. Unfortunately, no drug targets have been found in Ichthyophthirius multifiliis until now and further limited development of the novel drug for Ichthyophthiriasis. In this study, an iTRAQ-based quantitative proteomic analysis was used to find the target of malachite green (MG), exhibiting greater efficacy than the existing drugs, against I. multifiliis trophonts in situ. We also verified the proteomic results by RT-qPCR, TEM and cell apoptosis assay. Our results showed that major variations in protein abundance were found among many of the ribosome proteins, indicating ribosome might be a candidate target. Furthermore, GO and KEGG pathway analyses of differentially expressed proteins (DEPs) revealed that ribosome and PI3K-Akt signalling pathway were remarkably enriched. Taken together, the above DEPs were also verified by RT-qPCR and morphological observations. This study provides insights into the key proteins enriched in PI3K-Akt signal pathway and ribosome pathway as potential targets of MG killing I. multifiliis, which could be served as targets for other less toxic drugs and be tested as potential treatments for I. multifiliis.

Metformin prevents BAFF activation of Erk1/2 from B-cell proliferation and survival by impeding mTOR-PTEN/Akt signaling pathway

B-cell activating factor (BAFF) is an essential cytokine for B-cell maturation, differentiation and survival, and excess BAFF induces aggressive or neoplastic B-cell disorders and contributes to development of autoimmune diseases. Metformin, an anti-diabetic drug, has recently garnered a great attention due to its anti-proliferative and immune-modulatory features. However, little is known regarding the effect of metformin on BAFF-stimulated B cells. Here, we show that metformin attenuated human soluble BAFF (hsBAFF)-induced cell proliferation and survival by blocking the Erk1/2 pathway in normal and B-lymphoid (Raji) cells. Pretreatment with U0126, knockdown of Erk1/2, or expression of dominant negative MKK1 strengthened metformin's inhibition of hsBAFF-activated Erk1/2 and B-cell proliferation/viability, whereas expression of constitutively active MKK1 rendered high resistance to metformin. Further investigation found that overexpression of wild type PTEN or ectopic expression of dominant negative Akt potentiated metformin's suppression of hsBAFF-induced Erk1/2 activation and proliferation/viability in Raji cells, implying a PTEN/Akt-dependent mechanism involved. Furthermore, we noticed that metformin hindered hsBAFF-activated mTOR pathway in B cells. Inhibition of mTOR with rapamycin or knockdown of mTOR enhanced metformin's suppression of hsBAFF-induced phosphorylation of S6K1, PTEN, Akt, and Erk1/2, as well as B-cell proliferation/viability. These results indicate that metformin prevents BAFF activation of Erk1/2 from cell proliferation and survival by impeding mTOR-PTEN/Akt signaling pathway in normal and neoplastic B-lymphoid cells. Our findings support that metformin has a great potential for prevention of excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Rapamycin inhibits B-cell activating factor (BAFF)-stimulated cell proliferation and survival by suppressing Ca2+-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is a crucial survival factor for B cells, and excess BAFF contributes to development of autoimmune diseases. Recent studies have shown that rapamycin can prevent BAFF-induced B-cell proliferation and survival, but the underlying mechanism remains to be elucidated. Here we found that rapamycin inhibited human soluble BAFF (hsBAFF)-stimulated cell proliferation by inducing G₁-cell cycle arrest, which was through downregulating the protein levels of CDK2, CDK4, CDK6, cyclin A, cyclin D1, and cyclin E. Rapamycin reduced hsBAFF-stimulated cell survival by downregulating the levels of anti-apoptotic proteins (Mcl-1, Bcl-2, Bcl-xL and survivin) and meanwhile upregulating the levels of pro-apoptotic proteins (BAK and BAX). The cytostatic and cytotoxic effects of rapamycin linked to its attenuation of hsBAFF-elevated intracellular free Ca²⁺ ([Ca²⁺]_i). In addition, rapamycin blocked hsBAFF-stimulated B-cell proliferation and survival by preventing hsBAFF from inactivating PTEN and activating the Akt-Erk1/2 pathway. Overexpression of wild type PTEN or ectopic expression of dominant negative Akt potentiated rapamycin's suppression of hsBAFF-induced Erk1/2 activation and proliferation/viability in Raji cells. Interestingly, PP242 (mTORC1/2 inhibitor) or Akt inhibitor X, like rapamycin (mTORC1 inhibitor), reduced the basal or hsBAFF-induced [Ca²⁺]_i elevations. Chelating [Ca²⁺]_i with BAPTA/AM, preventing [Ca²⁺]_i elevation using EGTA, 2-APB or verapamil, inhibiting CaMKII with KN93, or silencing CaMKII strengthened rapamycin's inhibitory effects. The results indicate that rapamycin inhibits BAFF-stimulated B-cell proliferation and survival by blunting mTORC1/2-mediated [Ca²⁺]_i elevations and suppressing Ca²⁺-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway. Our finding underscores that rapamycin may be exploited for prevention of excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Wnt5a/CaMKII/ERK/CCL2 axis is required for tumor-associated macrophages to promote colorectal cancer progression

Tumor-associated macrophages (TAMs) are closely correlated with tumor occurrence, invasion, and metastasis. However, factors affecting the biological functions of TAMs in colorectal cancer (CRC) are incompletely understood. Here, we found that Wnt5a was mainly expressed on TAMs of tumor stroma but not on CRC cells. Subsequently, we found that Wnt5a⁺ TAMs facilitated tumor cell proliferation and migration, and recruited macrophages infiltration. Furthermore, Wnt5a knockdown impaired the pro-tumor roles of TAMs in vivo and in vitro. Mechanistically, the cancer-promoting roles of Wnt5a in TAMs depended on CaMKII-ERK pathway-mediated CCL2 secretion. Our data reveal the crucial role played by TAM-expressed Wnt5a in CRC tumorigenesis through paracrine secretion of CCL2. We first report the connection between Wnt5a/CaMKII/ERK/CCL2 axis and biological functions of TAMs in tumor microenvironment, indicating that Wnt5a may be a novel therapeutic target for CRC.

BAFF inhibits autophagy promoting cell proliferation and survival by activating Ca2+-CaMKII-dependent Akt/mTOR signaling pathway in normal and neoplastic B-lymphoid cells

B cell activating factor from the TNF family (BAFF) is implicated in not only the physiology of normal B cells, but also the pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Autophagy plays a crucial role in balancing the beneficial and detrimental effects of immunity and inflammation. However, little is known about whether and how excessive BAFF mediates autophagy contributing to B-cell proliferation and survival. Here, we show that excessive human soluble BAFF (hsBAFF) inhibited autophagy with a concomitant reduction of LC3-II in normal and B-lymphoid (Raji) cells. Knockdown of LC3 not only potentiated hsBAFF inhibition of autophagy, but also attenuated hsBAFF activation of Akt/mTOR pathway, thereby diminishing hsBAFF-induced B-cell proliferation/viability. Further, we found that hsBAFF inhibition of autophagy was Akt/mTOR-dependent. This is supported by the findings that hsBAFF increased mTORC1-mediated phosphorylation of ULK1 (Ser757); Akt inhibitor X, mTORC1 inhibitor rapamycin, mTORC1/2 inhibitor PP242, expression of dominant negative Akt, or knockdown of mTOR attenuated hsBAFF-induced phosphorylation of ULK1, decrease of LC3-II level, and increase of cell proliferation/viability. Chelating intracellular free Ca²⁺ ([Ca²⁺]_i) with BAPTA/AM or preventing [Ca²⁺]_i elevation using EGTA or 2-APB profoundly blocked hsBAFF-induced activation of Akt/mTOR, phosphorylation of ULK1 and decrease of LC3-II, as well as increase of cell proliferation/viability. Similar effects were observed in the cells where CaMKII was inhibited by KN93 or knocked down by CaMKII shRNA. Collectively, these results indicate that hsBAFF inhibits autophagy promoting cell proliferation and survival through activating Ca²⁺-CaMKII-dependent Akt/mTOR signaling pathway in normal and neoplastic B-lymphoid cells. Our findings suggest that manipulation of intracellular Ca²⁺ level or CaMKII, Akt, or mTOR activity to promote autophagy may be exploited for prevention of excessive BAFF-induced aggressive B lymphocyte disorders and autoimmune diseases.

Profiling the interactome of protein kinase C ζ by proteomics and bioinformatics

Background

Protein kinase C ζ (PKCζ), an isoform of the atypical protein kinase C, is a pivotal regulator in cancer. However, the molecular and cellular mechanisms whereby PKCζ regulates tumorigenesis and metastasis are still not fully understood. In this study, proteomics and bioinformatics analyses were performed to establish a protein-protein interaction (PPI) network associated with PKCζ, laying a stepping stone to further understand the diverse biological roles of PKCζ.

Methods

Protein complexes associated with PKCζ were purified by co-immunoprecipitation from breast cancer cell MDA-MB-231 and identified by LC-MS/MS. Two biological replicates and two technical replicates were analyzed. The observed proteins were filtered using the CRAPome database to eliminate the potential false positives. The proteomics identification results were combined with PPI database search to construct the interactome network. Gene ontology (GO) and pathway analysis were performed by PANTHER database and DAVID. Next, the interaction between PKCζ and protein phosphatase 2 catalytic subunit alpha (PPP2CA) was validated by co-immunoprecipitation, Western blotting and immunofluorescence. Furthermore, the TCGA database and the COSMIC database were used to analyze the expressions of these two proteins in clinical samples.

Results

The PKCζ centered PPI network containing 178 nodes and 1225 connections was built. Network analysis showed that the identified proteins were significantly associated with several key signaling pathways regulating cancer related cellular processes.

Conclusions

Through combining the proteomics and bioinformatics analyses, a PKCζ centered PPI network was constructed, providing a more complete picture regarding the biological roles of PKCζ in both cancer regulation and other aspects of cellular biology.

Electronic supplementary material

The online version of this article (10.1186/s12953-018-0134-8) contains supplementary material, which is available to authorized users.

Rapamycin attenuates BAFF-extended proliferation and survival via disruption of mTORC1/2 signaling in normal and neoplastic B-lymphoid cells

B cell activating factor from the TNF family (BAFF) stimulates B-cell proliferation and survival, but excessive BAFF promotes the development of aggressive B cells leading to malignant and autoimmune diseases. Recently, we have reported that rapamycin, a macrocyclic lactone, attenuates human soluble BAFF (hsBAFF)-stimulated B-cell proliferation/survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway. Here, we show that the inhibitory effect of rapamycin on hsBAFF-promoted B cell proliferation/survival is also related to blocking hsBAFF-stimulated phosphorylation of Akt, S6K1, and 4E-BP1, as well as expression of survivin in normal and B-lymphoid (Raji and Daudi) cells. It appeared that both mTORC1 and mTORC2 were involved in the inhibitory activity of rapamycin, as silencing raptor or rictor enhanced rapamycin's suppression of hsBAFF-induced survivin expression and proliferation/viability in B cells. Also, PP242, an mTORC1/2 kinase inhibitor, repressed survivin expression, and cell proliferation/viability more potently than rapamycin (mTORC1 inhibitor) in B cells in response to hsBAFF. Of interest, ectopic expression of constitutively active Akt (myr-Akt) or constitutively active S6K1 (S6K1-ca), or downregulation of 4E-BP1 conferred resistance to rapamycin's attenuation of hsBAFF-induced survivin expression and B-cell proliferation/viability, whereas overexpression of dominant negative Akt (dn-Akt) or constitutively hypophosphorylated 4E-BP1 (4EBP1-5A), or downregulation of S6K1, or co-treatment with Akt inhibitor potentiated the inhibitory effects of rapamycin. The findings indicate that rapamycin attenuates excessive hsBAFF-induced cell proliferation/survival via blocking mTORC1/2 signaling in normal and neoplastic B-lymphoid cells. Our data underscore that rapamycin may be a potential agent for preventing excessive BAFF-evoked aggressive B-cell malignancies and autoimmune diseases.

Persistent mechanical stretch-induced calcium overload and MAPK signal activation contributed to SCF reduction in colonic smooth muscle in vivo and in vitro

Gastrointestinal (GI) distention is a common pathological characteristic in most GI motility disorders (GMDs), however, their detail mechanism remains unknown. In this study, we focused on Ca²⁺ overload of smooth muscle, which is an early intracellular reaction to stretch, and its downstream MAPK signaling and also reduction of SCF in vivo and in vitro. We successfully established colonic dilation mouse model by keeping incomplete colon obstruction for 8 days. The results showed that persistent colonic dilation clearly induced Ca²⁺ overload and activated all the three MAPK family members including JNK, ERK and p38 in smooth muscle tissues. Similar results were obtained from dilated colon of patients with Hirschsprung's disease and stretched primary mouse colonic smooth muscle cells (SMCs). Furthermore, we demonstrated that persistent stretch-induced Ca²⁺ overload was originated from extracellular Ca²⁺ influx and endoplasmic reticulum (ER) Ca²⁺ release identified by treating with different Ca²⁺ channel blockers, and was responsible for the persistent activation of MAPK signaling and SCF reduction in colonic SMCs. Our results suggested that Ca²⁺ overload caused by smooth muscle stretch led to persistent activation of MAPK signaling which might contribute to the decrease of SCF and development of the GMDs.

IL-2, IL-4, IFN-γ or TNF-α enhances BAFF-stimulated cell viability and survival by activating Erk1/2 and S6K1 pathways in neoplastic B-lymphoid cells

B-cell activating factor of the TNF family (BAFF) has been documented to act as a critical factor in the development of aggressive B lymphocytes and autoimmune diseases. However, the effect of various cytokines on BAFF-elicited neoplastic B-lymphoid cells is not known. In this study, we exhibited that administration of human soluble BAFF (hsBAFF), IL-2, IL-4, IFN-γ, or TNF-α alone increased cell viability and survival in Raji cells concentration-dependently, yet a more robust viability/survival was seen in the cells co-treatment of IL-2, IL-4, IFN-γ, or TNF-α with hsBAFF, respectively. Further research revealed that both Erk1/2 and S6K1 signaling pathways were essential for IL-2, IL-4, IFN-γ, or TNF-α enhancement of the viability/survival in the hsBAFF-stimulated cells, as inhibition of Erk1/2 with U0126 or down-regulation of Erk1/2, or blockage of S6K1 with rapamycin or silencing S6K1, or silencing S6K1/Erk1/2, respectively, reduced the cell viability/survival in the cells treated with/without hsBAFF±IL-2, IL-4, IFN-γ, or TNF-α. These findings indicate that IL-2, IL-4, IFN-γ or TNF-α enhances BAFF-stimulated cell viability/survival by activating Erk1/2 and S6K1 signaling in neoplastic B-lymphoid cells. Our data suggest that modulation of IL-2, IL-4, IFN-γ and/or TNF-α levels, or inhibitors of Erk1/2 or S6K1 may be a new approach to prevent BAFF-induced aggressive B-cell malignancies.

Baicalin alleviates ischemia-induced memory impairment by inhibiting the phosphorylation of CaMKII in hippocampus

Baicalin has a significant neuroprotective effect in stroke. However, the mechanism remains unclear. This study was to reveal the mechanisms by which baicalin protected hippocampal neurons and improved learning and memory impairment after global cerebral ischemia/reperfusion in gerbil. In the present study, the Morris water maze test showed that baicalin significantly improved learning and memory impairment after global cerebral ischemia/reperfusion in gerbils. Laser scanning confocal fluorescence microscope examination showed that baicalin suppressed OGD-induced augmentation of intracellular calcium concentration. Western blotting analysis indicated that baicalin suppressed ischemia-caused elevated phosphorylation level of CaMKII in vivo, in hippocampal neurons in culture, and in SH-SY5Y cells in culture. Western blotting, TUNEL and RNA interference technology were applied to detect effects of baicalin on neuronal apoptosis. We found that baicalin, a CaMKII inhibitor and knocking down the CaMKII prevented OGD-induced apoptosis of hippocampal or SH-SY5Y cells in culture. Therefore, these results suggested that baicalin improves learning and memory impairment induced by global cerebral ischemia/reperfusion in gerbils via attenuating the phosphorylation level of CaMKII and further preventing hippocampal neuronal apoptosis.

The emerging role of CaMKII in cancer

Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional serine/threonine kinases best known for its critical role in learning and memory. Recent studies suggested that high levels of CaMKII also expressed in variety of malignant diseases. In this review, we focus on the structure and biology properties of CaMKII, including the role of CaMKII in the regulation of cancer progression and therapy response. We also describe the role of CaMKII in the diagnosis of different kinds of cancer and recent progress in the development of CaMKII inhibitors. These data establishes CaMKII as a novel target whose modulation presents new opportunities for cancer diagnosis and treatment.

Activation of LXR attenuates collagen-induced arthritis via suppressing BLyS production

B-lymphocyte stimulator (BLyS) plays a critical role in the pathogenesis and progression of rheumatoid arthritis (RA). Liver X receptor (LXR), a nuclear receptor, has an important anti-inflammatory effect. However, it is unclear whether the BLyS expression is regulated by LXR. In this study, we found that treatment with LXR agonist in collagen-induced arthritis (CIA) mice significantly attenuated arthritis progression, and markedly decreased BLyS production in serum and splenocytes as well as the production of serum IFNγ and TGFβ. Activation of LXR in B lymphocytes dramatically suppressed the basal and IFNγ/TGFβ-induced BLyS expression. Moreover, LXR agonist prominently suppressed the binding of NF-κB to BLyS promoter region, and decreased the promoter's transcriptional activity. Additionally, activation of LXR obviously repressed IFNγ-induced STAT1 activation and TGFβ-induced SMAD3 activation. These results indicated that downregulation of BLyS may be a novel mechanism by which LXR ameliorates RA, and LXR/BLyS pathway may serve as a novel target for the treatment of RA.

Rapamycin inhibits BAFF-stimulated cell proliferation and survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is involved in not only physiology of normal B cells, but also pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Rapamycin, a lipophilic macrolide antibiotic, has recently shown to be effective in the treatment of human lupus erythematosus. However, how rapamycin inhibits BAFF-stimulated B-cell proliferation and survival has not been fully elucidated. Here, we show that rapamycin inhibited human soluble BAFF (hsBAFF)-induced cell proliferation and survival in normal and B-lymphoid (Raji and Daudi) cells by activation of PP2A and inactivation of Erk1/2. Pretreatment with PD98059, down-regulation of Erk1/2, expression of dominant negative MKK1, or overexpression of wild-type PP2A potentiated rapamycin's suppression of hsBAFF-activated Erk1/2 and B-cell proliferation/viability, whereas expression of constitutively active MKK1, inhibition of PP2A by okadaic acid, or expression of dominant negative PP2A attenuated the inhibitory effects of rapamycin. Furthermore, expression of a rapamycin-resistant and kinase-active mTOR (mTOR-T), but not a rapamycin-resistant and kinase-dead mTOR-T (mTOR-TE), conferred resistance to rapamycin's effects on PP2A, Erk1/2 and B-cell proliferation/viability, implying mTOR-dependent mechanism involved. The findings indicate that rapamycin inhibits BAFF-stimulated cell proliferation/survival by targeting mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells. Our data highlight that rapamycin may be exploited for preventing excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Nociceptin/orphanin FQ-induced inhibition of delayed rectifier potassium currents by calcium/calmodulin-dependent protein kinase type II

The neuropeptide nociceptin/orphanin FQ (N/OFQ) has been shown to inhibit delayed rectifier potassium current (IK) in acutely dissociated rat parietal cortical neurons. However, the detailed mechanism of N/OFQ-induced inhibition on IK is not clear. This study is the first to explore an involvement of calcium/calmodulin (CaM)-dependent protein kinase type II (CaMKII) in mediating N/OFQ-induced responses. Utilizing pharmacological inhibitors of CaM and CaMKII, we have investigated the contribution of CaMKII in N/OFQ-induced effects using the whole-cell patch-clamp technique. In whole-cell voltage clamp, W-7 (100 μM), an antagonist of CaM, as well as KN-62, an inhibitor of CaMKII activity, attenuated the inhibitory effects of N/OFQ on IK. Activation and inactivation analysis indicated that the kinetics of IK were altered by N/OFQ, with decreased activation and promoted inactivation of IK. W-7 and KN-62 (10 μM) partly abolished the activation and inactivation curves shift of IK induced by N/OFQ. These findings show that CaMKII plays a critical role in N/OFQ-induced inhibition of IK in acutely dissociated rat parietal cortical neurons.

Effects of B-lymphocyte dysfunction on the serum copper, selenium and zinc levels of rheumatoid arthritis patients

Objective: To study the effects of B-lymphocyte dysfunction on the serum copper, selenium and zinc levels of rheumatoid arthritis (RA) patients, and to provide evidence for clinical practice.

Methods: Sixty RA patients enrolled in our hospital from August 2009 to August 2013 were selected as the observation group. Another 60 healthy subjects who received physical examinations in our hospital were selected as the control group. Their B-lymphocyte stimulator (BlyS) levels and CD19⁺CD25⁺ lymphocyte percentages were determined. The levels of trace elements were measured, and correlation analysis was performed.

Results: The BlyS levels of the observation group and the control group were (0.39±0.21) ng/ml and (0.13±0.04) ng/ml respectively, which were significantly different (P<0.05). The percentages of CD25⁺, CD19⁺ and CD19⁺CD25⁺ lymphocytes in the observation group were significantly higher than those in the control group (P<0.05). The serum copper, selenium and zinc levels of the observation group were significantly lower than those of the control group (P<0.05). Pearson's correlation analysis showed that the BlyS level was correlated with the levels of copper, selenium and zinc respectively (r=-0.541, -0.370, -0.430, P<0.05).

Conclusion: Rheumatoid Arthritis may be induced by BlyS-mediated B-lymphocyte dysplasia and dysfunction, accompanied by decreased expressions of copper, selenium and zinc.

CaMKII protects MKP-1 from proteasome degradation in endothelial cells

CaMKs are a widely distributed family of kinases with multiple and often cell specific effects on intracellular signal transduction pathway. In endothelial cells, it has been recognized a role for CamKII in several pathways such as eNOS activation and nitric oxide production. It is not clear though, whether CaMKII interfere with other endothelial cell functions such as ERK activation and cell proliferation. We explored this issue in primary cultured rat endothelial cells and we evaluated the effect on endothelial cell proliferation and DNA synthesis. CaMKII inhibition through Cantide, conducted into the cell through Antoennapedia (ANT-CN), showed positive effects on proliferation and H(3)-thimdine incorporation similar to insulin stimulation. Accordingly, both CaMKII pharmacological inhibition and silencing through shRNA produced activation of the p44/42 MAPK. These observations leaded to the hypothesis that CamKII could regulate p44/p42 by interfering with specific ERK phosphatases. Indeed, we found that CaMKII interacts and protect the dual specific phosphatase MKP-1 from proteasome mediated degradation while this complex is disrupted by CaMKII inhibitors. This study reveals that CaMKII, besides phosphorylation through the known ras-raf-mek pathway, can regulate also dephosphorylation of p44/p42 by modulation of MKP-1 level. This novel finding opens to a novel scenario in regulation of endothelial cell functions.