Role of MAPKs in development and differentiation: lessons from knockout mice

Surface Pre-Reacted Glass-Ionomer Eluate Suppresses Osteoclastogenesis through Downregulation of the MAPK Signaling Pathway

Surface pre-reacted glass-ionomer (S-PRG) is a new bioactive filler utilized for the restoration of decayed teeth by its ability to release six bioactive ions that prevent the adhesion of dental plaque to the tooth surface. Since ionic liquids are reported to facilitate transepithelial penetration, we reasoned that S-PRG applied to root caries could impact the osteoclasts (OCs) in the proximal alveolar bone. Therefore, this study aimed to investigate the effect of S-PRG eluate solution on RANKL-induced OC-genesis and mineral dissolution in vitro. Using RAW264.7 cells as OC precursor cells (OPCs), TRAP staining and pit formation assays were conducted to monitor OC-genesis and mineral dissolution, respectively, while OC-genesis-associated gene expression was measured using quantitative real-time PCR (qPCR). Expression of NFATc1, a master regulator of OC differentiation, and the phosphorylation of MAPK signaling molecules were measured using Western blotting. S-PRG eluate dilutions at 1/200 and 1/400 showed no cytotoxicity to RAW264.7 cells but did significantly suppress both OC-genesis and mineral dissolution. The same concentrations of S-PRG eluate downregulated the RANKL-mediated induction of OCSTAMP and CATK mRNAs, as well as the expression of NFATc1 protein and the phosphorylation of ERK, JNK, and p38. These results demonstrate that S-PRG eluate can downregulate RANKL-induced OC-genesis and mineral dissolution, suggesting that its application to root caries might prevent alveolar bone resorption.

High-throughput sequencing reveals hub genes for human early embryonic development arrest in vitro fertilization: a pilot study

Many clinical studies have shown that embryos of in vitro fertilization (IVF) are often prone to developmental arrest, which leads to recurrent failure of IVF treatment. Early embryonic arrest has always been an urgent clinical problem in assisted reproduction centers. However, the molecular mechanisms underlying early embryonic development arrest remain largely unknown. The objective of this study is to investigate potential candidate hub genes and key signaling pathways involved in early stages of embryonic development. RNA-seq analysis was performed on normal and arrest embryos to study the changes of gene expression during early embryonic development. A total of 520 genes exhibiting differential expression were identified, with 174 genes being upregulated and 346 genes being downregulated. Upregulated genes show enrichment in biosynthesis, cellular proliferation and differentiation, and epigenetic regulation. While downregulated genes exhibit enrichment in transcriptional activity, epigenetic regulation, cell cycle progression, cellular proliferation and ubiquitination. The STRING (search tool for the retravel of interacting genes/proteins) database was utilized to analyze protein-protein interactions among these genes, aiming to enhance comprehension of the potential role of these differentially expressed genes (DEGs). A total of 22 hub genes (highly connected genes) were identified among the DEGs using Cytoscape software. Of these, ERBB2 and VEGFA were upregulated, while the remaining 20 genes (CCNB1, CCNA2, DICER1, NOTCH1, UBE2B, UBE2N, PRMT5, UBE2D1, MAPK3, SOX9, UBE2C, UB2D2, EGF, ACTB, UBA52, SHH, KRAS, UBE2E1, ADAM17 and BRCA2) were downregulated. These hub genes are associated with crucial biological processes such as ubiquitination, cellular senescence, cell proliferation and differentiation, and cell cycle. Among these hub genes, CCNA2 and CCNB1 may be involved in controlling cell cycle, which are critical process in early embryonic development.

A patent review of MAPK inhibitors (2018 - present)

INTRODUCTION

The mitogen-activated protein kinase (MAPK) family consist of p38 MAP kinases, c-Jun N-terminal kinases (JNKs) and extracellular signal-regulated kinases (ERKs). They are involved in a multitude of diseases, including inflammatory, autoimmune, neurodegenerative, and metabolic diseases as well as cancer. In recent years, further developments in the field of MAPK-inhibitors have been reported, including an isoform or downstream target selective inhibition of MAPKs as well as target protein degradation approaches.

AREAS COVERED

This review summarizes newly patented MAPK-inhibitors that were claimed between 2018 and early 2023. Presented are the patents as well as their corresponding publications, the storyline of development, and clinical trials involving these compounds. This article elaborates a total of 27 patents, which were identified using established search engines.

EXPERT OPINION

Although industrial research on MAPK-inhibitors has been ongoing for more than 20 years, novel clinical trials of MAPK-inhibitors as potential drug candidates are still being conducted in the period under review. Recently reported inhibitors show an excellent selectivity profile and are even achieving selectivity between closely related isoforms. This progression offers the possibility to eliminate unwanted side effects and may finally lead to the approval of the first MAPK-inhibitor.

Stress signaler p38 mitogen-activated kinase activation: a cause for concern?

Oxidative stress (OS) induced activation of p38 mitogen-activated kinase (MAPK) and cell fate from p38 signaling was tested using the human fetal membrane's amnion epithelial cells (AEC). We created p38 KO AEC using the CRISPR/Cas9 approach and tested cell fate in response to OS on an AEC-free fetal membrane extracellular matrix (ECM). Screening using image CyTOF indicated OS causing epithelial-mesenchymal transition (EMT). Further testing revealed p38 deficiency prevented AEC senescence, EMT, cell migration, and inflammation. To functionally validate in vitro findings, fetal membrane-specific conditional KO (cKO) mice were developed by injecting Cre-recombinase encoded exosomes intra-amniotically into p38αloxP/loxP mice. Amnion membranes from p38 cKO mice had reduced senescence, EMT, and increased anti-inflammatory IL-10 compared with WT animals. Our study suggested that overwhelming activation of p38 in response to OS inducing risk exposures can have an adverse impact on cells, cause cell invasion, inflammation, and ECM degradation detrimental to tissue homeostasis.

ERK5 Signalling and Resistance to ERK1/2 Pathway Therapeutics: The Path Less Travelled?

The RAS-regulated RAF-MEK1/2-ERK1/2 signalling pathway is frequently de-regulated in human cancer. Melanoma in particular exhibits a high incidence of activating BRAFV600E/K and NRASQ61L/K mutations and such cells are addicted to the activity of these mutant oncoproteins. As a result three different BRAF inhibitors (BRAFi) have now been approved for BRAFV600E/K- mutant melanoma and have transformed the treatment of this disease. Despite this, clinical responses are typically transient as tumour cells develop resistance. These resistance mechanisms frequently involve reinstatement of ERK1/2 signalling and BRAFi are now deployed in combination with one of three approved MEK1/2 inhibitors (MEKi) to provide more durable, but still transient, clinical responses. Furthermore, inhibitors to ERK1/2 (ERK1/2i) have also been developed to counteract ERK1/2 signalling. However, recent studies have suggested that BRAFi/MEKi and ERK1/2i resistance can arise through activation of a parallel signalling pathway leading to activation of ERK5, an unusual protein kinase that contains both a kinase domain and a transcriptional transactivation domain. Here we review the evidence supporting ERK5 as a mediator of BRAFi/MEKi and ERK1/2i resistance. We also review the challenges in targeting ERK5 signalling with small molecules, including paradoxical activation of the transcriptional transactivation domain, and discuss new therapeutic modalities that could be employed to target ERK5.

Structural optimization of 4-(imidazol-5-yl)pyridine derivatives affords broad-spectrum anticancer agents with selective B-RAFV600E/p38α kinase inhibitory activity: Synthesis, in vitro assays and in silico study

In the current article, we introduce design of a new series of 4-(imidazol-5-yl)pyridines with improved anticancer activity and selective B-RAF^V600E/p38α kinase inhibitory activity. Based on a previous work, a group of structural modifications were applied affording the new potential antiproliferative agents. Towards extensive biological assessment of the target compounds, an in vitro anticancer assay was conducted over NCI 60-cancer cell lines panel representing blood, lung, colon, CNS, skin, ovary, renal, prostate, and breast cancers. Compounds 7c, 7d, 8b, 9b, 9c, 10c, 10d, and 11b exhibited the highest potency among the tested compounds and demonstrated sub-micromolar or one-digit micromolar GI₅₀ values against the majority of the employed cell lines. Compound 10c emerged as the most potent agent with nano-molar activity over most of the cells and incredible activity against melanoma (MDA-MB-435) cell line (GI₅₀ 70 nM). It is much more potent than sorafenib, the clinically used anticancer drug, against almost all the NCI-60 cell lines. Further cell-based mechanistic assays showed that compound 10c induced cell cycle arrest and promoted apoptosis in K562, MCF-7 and HT29 cancer cell lines. In addition, compound 10c induced autophagy in the three cancer cell lines. Kinase profiling of 10c showed its inhibitory effects and selectivity towards B-RAF^V600E and p38α kinases with IC₅₀ values of 1.84 and 0.726 µM, respectively. Docking of compound 10c disclosed its high affinity in the kinases pockets. Compound 10c represent a promising anticancer agent, that could be optimized in order to improve its kinase activity aiming at developing potential anticancer agents. The conformational stability of compound 10c in the active site of B-RAF^V600E and p38α kinases was studied by applying molecular dynamic simulation of the compound in the two kinases for 600 ns in comparison to the native ligands.

Dual Mkk4 and Mkk7 Gene Deletion in Adult Mouse Causes an Impairment of Hippocampal Immature Granule Cells

(1) Background: The c-Jun-NH2-terminal protein kinase (JNK) is a mitogen-activated protein kinase involved in regulating physiological processes in the central nervous system. However, the dual genetic deletion of Mkk4 and Mkk7 (upstream activators of JNK) in adult mice is not reported. The aim of this study was to induce the genetic deletion of Mkk4/Mkk7 in adult mice and analyze their effect in hippocampal neurogenesis. (2) Methods: To achieve this goal, Actin-Cre^ERT2 (Cre^+/-), Mkk4^flox/flox, Mkk7^flox/flox mice were created. The administration of tamoxifen in these 2-month-old mice induced the gene deletion (Actin-Cre^ERT2 (Cre^+/-), Mkk4^∆/∆, Mkk7^∆/∆ genotype), which was verified by PCR, Western blot, and immunohistochemistry techniques. (3) Results: The levels of MKK4/MKK7 at 7 and 14 days after tamoxifen administration were not eliminated totally in CNS, unlike what happens in the liver and heart. These data could be correlated with the high levels of these proteins in CNS. In the hippocampus, the deletion of Mkk4/Mkk7 induced a misalignment position of immature hippocampal neurons together with alterations in their dendritic architecture pattern and maturation process jointly to the diminution of JNK phosphorylation. (4) Conclusion: All these data supported that the MKK4/MKK7-JNK pathway has a role in adult neurogenic activity.

When Good Kinases Go Rogue: GSK3, p38 MAPK and CDKs as Therapeutic Targets for Alzheimer's and Huntington's Disease

Alzheimer's disease (AD) is a mostly sporadic brain disorder characterized by cognitive decline resulting from selective neurodegeneration in the hippocampus and cerebral cortex whereas Huntington's disease (HD) is a monogenic inherited disorder characterized by motor abnormalities and psychiatric disturbances resulting from selective neurodegeneration in the striatum. Although there have been numerous clinical trials for these diseases, they have been unsuccessful. Research conducted over the past three decades by a large number of laboratories has demonstrated that abnormal actions of common kinases play a key role in the pathogenesis of both AD and HD as well as several other neurodegenerative diseases. Prominent among these kinases are glycogen synthase kinase (GSK3), p38 mitogen-activated protein kinase (MAPK) and some of the cyclin-dependent kinases (CDKs). After a brief summary of the molecular and cell biology of AD and HD this review covers what is known about the role of these three groups of kinases in the brain and in the pathogenesis of the two neurodegenerative disorders. The potential of targeting GSK3, p38 MAPK and CDKS as effective therapeutics is also discussed as is a brief discussion on the utilization of recently developed drugs that simultaneously target two or all three of these groups of kinases. Multi-kinase inhibitors either by themselves or in combination with strategies currently being used such as immunotherapy or secretase inhibitors for AD and knockdown for HD could represent a more effective therapeutic approach for these fatal neurodegenerative diseases.

Design, synthesis, biological evaluation, and docking studies of novel (imidazol-5-yl)pyrimidine-based derivatives as dual BRAFV600E/p38α inhibitors

The synergistic effect of dual inhibition of serine/threonine protein kinases that are involved in the same signalling pathway of the diseases can exert superior biological benefits for treatment of these diseases. In the present work, a new series of (imidazol-5-yl)pyrimidine was designed and synthesized as dual inhibitors of BRAF^V600E and p38α kinases which are considered as key regulators in mitogen-activated protein kinase (MAPK) signalling pathway. The target compounds were evaluated for dual kinase inhibitory activity. The tested compounds exhibited nanomolar scale IC₅₀ values against BRAF^V600E and low to sub-micromolar IC₅₀ range against p38α. Compound 20h was identified as the most potent dual BRAF^V600E/p38α inhibitor with IC₅₀ values of 2.49 and 85 nM, respectively. Further deep investigation revealed that compound 20h possesses inhibitory activity of TNF-α production in lipopolysaccharide-induced RAW 264.7 macrophages with IC₅₀ value of 96.3 nM. Additionally, the target compounds efficiently frustrated the proliferation of LOX-IMVI melanoma cell line. Compound 20h showed a satisfactory antiproliferative activity with IC₅₀ value of 13 μM, while, compound 18f exhibited the highest cytotoxicity potency with IC₅₀ value of 0.9 μM. Compound 18f is 11.11-fold more selective toward LOX-IMVI melanoma cells than IOSE-80PC normal cells. The newly reported compounds represent therapeutically promising candidates for further development of BRAF^V600E/p38α inhibitors in an attempt to overcome the acquired resistance of BRAF mutant melanoma.

Lidocaine attenuates CFA-induced inflammatory pain in rats by regulating the MAPK/ERK/NF-κB signaling pathway

Lidocaine is a commonly used local anesthetic that also confers analgesic effects, resistance to hyperalgesia and anti-inflammatory properties. The present study aimed to explore the effects of lidocaine on complete Freund's adjuvant (CFA)-induced inflammatory pain. In the present study, rats were subcutaneously injected with CFA to investigate the molecular mechanisms associated with lidocaine in an inflammation-induced pain model. Firstly, CFA was subcutaneously injected into the paws of Sprague-Dawley rats, following which lidocaine or saline and the ERK agonist recombinant human epidermal growth factor (rh-EGF) were injected via the tail vein. Rat behavior was then assessed at 0 and 4 h, 1, 4, 7 and 14 days after CFA treatment. Proinflammatory cytokine levels in the serum were measured using ELISA. Western blotting was performed to detect the protein levels of phosphorylated (p)-ERK1/2, ERK1/2 and NF-κB subunits p-p65 and p65. Reverse transcription-quantitative PCR was used to measure the mRNA expression of ERK1/2 and p65 in rat spinal cord tissues. The results showed that injection of CFA significantly reduced the mechanical withdrawal threshold, thermal withdrawal latency and the frequency of responses to cold stimulation in rats, whilst promoting tumor necrosis factor-α, interleukin (IL)-1β, IL-6 levels in addition to ERK1/2, p65 protein phosphorylation. These effects were alleviated by lidocaine treatment. Furthermore, treatment with rh-EGF reversed the protective effects of lidocaine on inflammatory pain caused by CFA. In conclusion, lidocaine inhibits the inflammatory response and pain through the MAPK/ERK/NF-κB pathway in a rat model of pain induced by CFA.

Glutamatergic Fate of Neural Progenitor Cells of Rats with Inherited Audiogenic Epilepsy

Epilepsy is associated with aberrant neurogenesis in the hippocampus and may underlie the development of hereditary epilepsy. In the present study, we analyzed the differentiation fate of neural progenitor cells (NPC), which were isolated from the hippocampus of embryos of Krushinsky-Molodkina (KM) rats genetically prone to audiogenic epilepsy. NPCs from embryos of Wistar rats were used as the control. We found principal differences between Wistar and KM NPC in unstimulated controls: Wistar NPC culture contained both gamma-aminobutyric acid (GABA) and glutamatergic neurons; KM NPC culture was mainly represented by glutamatergic cells. The stimulation of glutamatergic differentiation of Wistar NPC resulted in a significant increase in glutamatergic cell number that was accompanied by the activation of protein kinase A. The stimulation of KM NPC led to a decrease in immature glutamatergic cell number and was associated with the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and protein kinase B/ glycogen synthase kinase 3 beta (Akt/GSK3β), which indicates the activation of glutamatergic cell maturation. These results suggest genetically programmed abnormalities in KM rats that determine the glutamatergic fate of NPC and contribute to the development of audiogenic epilepsy.

Alternative splicing of jnk1a in zebrafish determines first heart field ventricular cardiomyocyte numbers through modulation of hand2 expression

The planar cell polarity pathway is required for heart development and whilst the functions of most pathway members are known, the roles of the jnk genes in cardiac morphogenesis remain unknown as mouse mutants exhibit functional redundancy, with early embryonic lethality of compound mutants. In this study zebrafish were used to overcome early embryonic lethality in mouse models and establish the requirement for Jnk in heart development. Whole mount in-situ hybridisation and RT-PCR demonstrated that evolutionarily conserved alternative spliced jnk1a and jnk1b transcripts were expressed in the early developing heart. Maternal zygotic null mutant zebrafish lines for jnk1a and jnk1b, generated using CRISPR-Cas9, revealed a requirement for jnk1a in formation of the proximal, first heart field (FHF)-derived portion of the cardiac ventricular chamber. Rescue of the jnk1a mutant cardiac phenotype was only possible by injection of the jnk1a EX7 Lg alternatively spliced transcript. Analysis of mutants indicated that there was a reduction in the size of the hand2 expression field in jnk1a mutants which led to a specific reduction in FHF ventricular cardiomyocytes within the anterior lateral plate mesoderm. Moreover, the jnk1a mutant ventricular defect could be rescued by injection of hand2 mRNA. This study reveals a novel and critical requirement for Jnk1 in heart development and highlights the importance of alternative splicing in vertebrate cardiac morphogenesis. Genetic pathways functioning through jnk1 may be important in human heart malformations with left ventricular hypoplasia.

Surface modification of titanium manufactured through selective laser melting inhibited osteoclast differentiation through mitogen-activated protein kinase signaling pathway

Selective laser melting used in manufacturing custom-made titanium implants becomes more popular. In view of the important role played by osteoclasts in peri-implant bone resorption and osseointegration, we modified selective laser melting-manufactured titanium surfaces using sandblasting/alkali-heating and sandblasting/acid-etching, and investigated their effect on osteoclast differentiation as well as their underlying mechanisms. The properties of the surfaces, including elements, roughness, wettability and topography, were analyzed. We evaluated the proliferation and morphology of primary mouse bone marrow-derived monocytes, as well as induced osteoclasts derived from bone marrow-derived monocytes, on samples. Then, osteoclast differentiation was determined by the tartrate-resistant acid phosphatase activity assay, calcitonin receptors immunofluorescence staining and the expression of osteoclast-related genes. The results showed that sandblasting/alkali-heating established nanonet structure with the lowest water contact angle, and both sandblasting/alkali-heating and sandblasting/acid-etching significantly decreased surface roughness and heterogeneity compared with selective laser melting. Surface modifications of selective laser melting-produced titanium altered bone marrow-derived monocyte morphology and suppressed bone marrow-derived monocyte proliferation and osteoclastogenesis in vitro (sandblasting/alkali-heating>sandblasting/acid-etching>selective laser melting). These surface modifications reduced the activation of extracellular signal-regulated kinase and c-Jun N-terminal kinases compared to native-selective laser melting. Sandblasting/alkali-heating additionally blocked tumor necrosis factor receptor-associated factor 6 recruitment. The results suggested that sandblasting/alkali-heating and sandblasting/acid-etching modifications on selective laser melting titanium could inhibit osteoclast differentiation through suppressing extracellular signal-regulated kinase and c-Jun N-terminal kinase phosphorylation in mitogen-activated protein kinase signaling pathway and provide a promising technique which might reduce peri-implant bone resorption for optimizing native-selective laser melting implants.

Thiamine Deficiency Modulates p38MAPK and Heme Oxygenase-1 in Mouse Brain: Association with Early Tissue and Behavioral Changes

Thiamine deficiency (TD) produces severe neurodegenerative lesions. Studies have suggested that primary neurodegenerative events are associated with both oxidative stress and inflammation. Very little is known about the downstream effects on intracellular signaling pathways involved in neuronal death. The primary aim of this work was to evaluate the modulation of p38^MAPK and the expression of heme oxygenase 1 (HO-1) in the central nervous system (CNS). Behavioral, metabolic, and morphological parameters were assessed. Mice were separated into six groups: control (Cont), TD with pyrithiamine (Ptd), TD with pyrithiamine and Trolox (Ptd + Tr), TD with pyrithiamine and dimethyl sulfoxide (Ptd + Dmso), Trolox (Tr) and DMSO (Dmso) control groups and treated for 9 days. Control groups received standard feed (AIN-93M), while TD groups received thiamine deficient feed (AIN-93DT). All the groups were subjected to behavioral tests, and CNS samples were collected for cell viability, histopathology and western blot analyses. The Ptd group showed a reduction in weight gain and feed intake, as well as a reduction in locomotor, grooming, and motor coordination activities. Also, Ptd group showed a robust increase in p38^MAPK phosphorylation and mild HO-1 expression in the cerebral cortex and thalamus. The Ptd group showed a decreased cell viability, hemorrhage, spongiosis, and astrocytic swelling in the thalamus. Groups treated with Trolox and DMSO displayed diminished p38^MAPK phosphorylation in both the structures, as well as attenuated thalamic lesions and behavioral activities. These data suggest that p38^MAPK and HO-1 are involved in the TD-induced neurodegeneration in vivo, possibly modulated by oxidative stress and neuroinflammation.

New Insights into the Process of Placentation and the Role of Oxidative Uterine Microenvironment

For a successful pregnancy to occur, a predecidualized receptive endometrium must be invaded by placental differentiated cells (extravillous trophoblast cells (EVTs)) and, at the same time, continue decidualization. EVT invasion is aimed at anchoring the placenta to the maternal uterus and ensuring local blood supply increase necessary to provide normal placental and foetal development. The first is achieved by migrating through the maternal endometrium and deeper into the myometrium, while the second by transforming uterine spiral arteries into large vessels. This process is a tightly regulated battle comprising interests of both the mother and the foetus. Invading EVTs are required to perform a scope of functions: move, adhere, proliferate, differentiate, interact, and digest the extracellular matrix (ECM); tolerate hypoxia; transform the maternal spiral arteries; and die by apoptosis. All these functions are modulated by their surrounding microenvironment: oxygen, soluble factors (e.g., cytokines, growth factors, and hormones), ECM proteins, and reactive oxygen species. A deeper comprehension of oxidative uterine microenvironment contribution to trophoblast function will be addressed in this review.

The role of Wnt7B in the mediation of dentinogenesis via the ERK1/2 pathway

OBJECTIVES

This study investigates the role of Wnt7b in mouse dentin formation.

DESIGN

C57BL/6 mouse tooth germs at different developmental stages were collected to measure the expression of Wnt7b by immunohistochemical staining. The morphology of mandibles of Dmp1-cre;ROSA26-Wnt7b transgenic mice and ROSA26-Wnt7b littermates was analyzed by Micro-CT and HE staining. The ultramicrostructure of dentin was scanned with an electron microscope. Primary mouse dental papillae cells (MDPCs) and odontoblastic cell line (A11) were cultured and infected with adenovirus to overexpress Wnt7b. Cell proliferation and cell apoptosis were evaluated using CCK-8 and flow cytometry. Osteogenic differentiation of MDPCs and A11 was assessed by Alizarin red staining, and qPCR detection of osteogenic gene expression. The activation of signaling pathways was measured by the use of western blot analysis. The ERK1/2 inhibitor was used to test the effect of Wnt7b regulated cell differentiation.

RESULTS

Wnt7b was expressed principally in the mouse odontoblast layer after the early bell stage. In transgenic mice, Wnt7b was over-expressed in tooth mesenchyme, with a thinner predentin layer and thicker intertubular dentin. Both the micro-hardness value and the Ca/Pi ratio of dentin of transgenic mice were higher. Wnt7b promoted proliferation and mineralization of MDPCs and A11. The protein level of p-ERK1/2 was found to be higher in A11 infected with Ad-Wnt7b. The ERK signaling pathway inhibitor partly rescued the Wnt7b-induced differentiation of A11.

CONCLUSIONS

Wnt7b enhances dentinogenesis by increasing the proliferation and differentiation of dental mesenchymal cells partly through ERK1/2 pathway.

Downregulation of CDKL1 suppresses neuroblastoma cell proliferation, migration and invasion

BACKGROUND

Cyclin-dependent kinase-like 1 (CDKL1) is a member of the cell division control protein 2-related serine-threonine protein kinase family. It is known to occur in various malignant tumors, but its role in neuroblastoma (NB) remains unclear.

METHODS

We constructed a CDKL1-silenced NB cell strain (SH-SY5Y) and used real-time PCR and western blotting to confirm the silencing. Functional analyses were performed using the MTT, colony-formation, FACS, wound-healing and transwell invasion assays.

RESULTS

The expression of CDKL1 was significantly upregulated in NB tissue as compared to the adjacent normal tissue. CDKL1 knockdown significantly suppressed cell viability and colony formation ability. It also induced cell cycle G0/G1 phase arrest and apoptosis, and suppressed the migration and invasion ability of SH-SY5Y cells. CDKL1 knockdown decreased the CDK4, cyclin D1 and vimentin expression levels, and increased the caspase-3, PARP and E-cadherin expression levels in SH-SY5Y cells.

CONCLUSIONS

Our findings suggest that CDKL1 plays an important role in NB cell proliferation, migration and invasion. It might serve as a potential target for NB therapy.

Role for ERK1/2-dependent activation of FCHSD2 in cancer cell-selective regulation of clathrin-mediated endocytosis

Clathrin-mediated endocytosis (CME) regulates the uptake of cell-surface receptors as well as their downstream signaling activities. We recently reported that signaling can reciprocally regulate CME in cancer cells and that this crosstalk can contribute to cancer progression. To further explore the nature and extent of the crosstalk between signaling and CME in cancer cell biology, we analyzed a panel of oncogenic signaling kinase inhibitors for their effects on CME across a panel of normal and cancerous cells. Inhibition of several kinases selectively affected CME in cancer cells, including inhibition of ERK1/2, which selectively inhibited CME by decreasing the rate of clathrin-coated pit (CCP) initiation. We identified an ERK1/2 substrate, the FCH/F-BAR and SH3 domain-containing protein FCHSD2, as being essential for the ERK1/2-dependent effects on CME and CCP initiation. Our data suggest that ERK1/2 phosphorylation activates FCHSD2 and regulates EGF receptor (EGFR) endocytic trafficking as well as downstream signaling activities. Loss of FCHSD2 activity in nonsmall cell lung cancer (NSCLC) cells leads to increased cell-surface expression and altered signaling downstream of EGFR, resulting in enhanced cell proliferation and migration. The expression level of FCHSD2 is positively correlated with higher NSCLC patient survival rates, suggesting that FCHSD2 can negatively affect cancer progression. These findings provide insight into the mechanisms and consequences of the reciprocal regulation of signaling and CME in cancer cells.

MAPKK Inhibitor U0126 Inhibits Plasmodiophora brassicae Development

Mitogen-activated protein kinase (MAPK) cascades play a central role in cellular growth, proliferation, and survival. MAPK cascade genes have been extensively investigated in model plants, mammals, yeast, and fungi but are not characterized in Plasmodiophora brassicae, which causes clubroot disease in cruciferous plants. Here, we identified 7 PbMAPK, 3 PbMAPKK, and 9 PbMAPKKK genes in the P. brassicae genome. Transcriptional profiling analysis demonstrated that several MAPK, MAPK kinase (MAPKK), and MAPK kinase kinase (MAPKKK) genes were preferentially expressed in three different zoosporic stages. Based on yeast two-hybrid assays, PbMAKKK7 interacted with PbMAKK3 and PbMAKK3 interacted with PbMAK1/PbMAK3. The PbMAKKK7-PbMAKK3-PbMAK1/PbMAK3 cascade may be present in P. brassicae. U0126, a potent and specific inhibitor of MAPKK, could inhibit the germination of P. brassicae resting spores. U0126 was used to treat the resting spores of P. brassicae and coinoculate rapeseed, and was proven to significantly relieve the severity of clubroot symptoms in the host plant and delay the life cycle of P. brassicae. These results suggest that MAPK signaling pathways may play important roles in P. brassicae growth, development, and pathogenicity.

Targeting incretin hormones and the ASK-1 pathway as therapeutic options in the treatment of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is currently one of the leading forms of chronic liver disease, and its rising frequency worldwide has reached epidemic proportions. NAFLD, particularly its progressive variant NASH (non-alcoholic steatohepatitis), can lead to advanced fibrosis, cirrhosis, and HCC. The pathophysiologic mechanisms that contribute to the development and progression of NAFLD and NASH are complex, and as such myriad therapies are under investigation targeting different pathophysiological mechanisms. Incretin-based therapies, including GLP-1RAs and DPP-4 inhibitors and the inhibition of ASK1 pathway have provided two such novel mechanisms in the management of this disease, and will remain focus of this review.

Suppression of Nestin reveals a critical role for p38-EGFR pathway in neural progenitor cell proliferation

The expression of intermediate filament Nestin is necessary for the neural progenitor cells (NPCs) to maintain stemness, but the underlying cellular and molecular mechanism remains unclear. In this study, we demonstrated that Nestin is required for the self-renew of NPCs through activating MAPK and EGFR pathways. Knockdown of Nestin by shRNA inhibited cell cycle progression and proliferation in mouse NPCs. Moreover, suppression of Nestin reduced expression of the epidermal growth factor receptor (EGFR) in NPCs and inhibited the mitogenic effects of EGF on these cells. Treatment of NPCs with p38-MAPK inhibitor PD169316 reversed cell cycle arrest caused by the knockdown of Nestin. Our findings indicate that Nestin promotes NPC proliferation via p38-MAPK and EGFR pathways, and reveals the necessity of these pathways in NPCs self-renewal.

Regulation and function of apoptosis signal-regulating kinase 1 in rheumatoid arthritis

Despite improved therapy, rheumatoid arthritis (RA) remains an unmet medical need. Previous efforts to validate therapeutic targets in the mitogen-activated protein kinase (MAPK) family have had minimal success. Therefore, we evaluated the potential for targeting an upstream MAPK, namely apoptosis signal-regulating kinase 1 (ASK1), as an alternative approach. ASK1 protein and gene expression were observed in RA and osteoarthritis (OA) synovium as determined by immunohistochemistry (IHC) and qPCR, respectively, particularly in the synovial intimal lining. For RA, but not OA synovium, ASK1 correlated with IL-1β and TNF gene expression. ASK1 was also expressed by cultured fibroblast-like synoviocytes (FLS), with significantly higher levels in RA compared with OA cells. IL-1β and TNF stimulation significantly increased ASK1 expression in a time-and concentration-dependent manner in cultured FLS. ASK1 promoter activity was significantly increased by IL-1β and TNF and was dependent on an upstream RelA binding motif. A selective small molecule ASK1 inhibitor reduced RA FLS invasion, migration and proliferation in vitro and decreased arthritis severity in the rat collagen-induced arthritis (CIA) model. In summary, our findings demonstrate that ASK1 modulates signaling pathways relevant to RA in vitro and in vivo. It is induced by inflammatory cytokines through the activation of NF-κB, which could provide some site- and event specificity. Thus, inhibitors of the upstream MAPK ASK1 could be a novel approach to treating inflammatory arthritis.

Placenta-specific gene manipulation using lentiviral vector and its application

The placenta is an essential organ for embryo development in the uterus of eutherian mammals. Large contributions in unveiling molecular mechanisms and physiological functions underlying placental formation were made by analyzing mutant and transgenic animals. However, it had been difficult to elucidate whether the placental defects observed in such animals originate from the placenta itself or from the fetus, as both placental and fetal genomes are modified. Therefore strategies to modify the placental genome without affecting the "fetal genome" had been needed. Through the ingenious use of lentiviral (LV) vectors, placenta-specific modification is now possible. Lentivirus is a genus of retroviruses that use reverse-transcriptase to convert its single-strand RNA genome to double-strand DNA and integrate into the host genome. Previous studies showed that when LV vectors were used to transduce embryos at the 2-cell stage, the viral genome is systemically introduced into host genome. Interestingly, by delaying the timing of transduction to the blastocyst stage, the transgene is expressed specifically in the placenta as a consequence of trophectoderm-specific viral transduction. This review summarizes the development of the LV vector-mediated placenta-specific gene manipulation technology and its application in placental research over the past decade. A perspective for future application of LV vectors to further placenta research, especially in combination with next generation genome editing technologies, is also presented.

Expression patterns of p38αMAPK during follicular development in the ovaries of neonatal rats

The p38αMAPK signaling pathway plays a critical role in female reproduction, but an understanding of its expression in rats remains elusive. This study was carried out to investigate the temporal and spatial expression of p38αMAPK and p-p38αMAPK. Ovarian tissue samples were collected from 2-, 4-, 8-, 12-, 16-, 20- and 30-day-old female rats. Western blotting was used to examine the relative expression of p38αMAPK and p-p38αMAPK in ovarian tissue, and subcellular localization was examined using immunohistochemistry of the rat ovaries at different ages of postpartum. The immunohistochemical results showed that p38αMAPK and p-p38αMAPK were widely expressed in the rat ovaries, mainly localized in the follicle cells and granulosa cells. The expression of p38αMAPK was relatively stable for the different stages of oocytes, whereas the expression of p-p38αMAPK gradually increased. At different stages of granulosa cells, the expression of p38αMAPK was also relatively stable, and the p-p38αMAPK expression showed an upward trend during follicular development. Western blotting revealed that the expression of p38αMAPK in the ovaries was relatively stable, where as p-p38αMAPK expression initially exhibited an increasing trend and subsequently decreased, with a maximum at day 20. The expression patterns of p38αMAPK and p-p38αMAPK in the rat ovaries indicate their possible involvement in folliculogenesis. Taken together, the stage- and cell-specific expression of p-p38αMAPK in rat ovaries indicated that p-p38αMAPK might play a vital role during rat follicular development.

TRPC6-mediated ERK1/2 phosphorylation prevents dentate granule cell degeneration via inhibiting mitochondrial elongation

Transient receptor potential canonical channel-6 (TRPC6) is one of Ca²⁺-permeable non-selective cation channels. In the rat hippocampus, TRPC6 expression is predominantly observed in dentate granule cells (DGC) rather than other hippocampal components. Interestingly, TRPC6 knockdown results in the massive DGC degeneration following status epilepticus (SE), although DGC is one of the resistant neuronal populations to various harmful stresses. However, the molecular events underlying the DGC degeneration induced by TRPC6 knockdown are still unclear. In the present study, TRPC6 knockdown resulted in mitochondrial elongation accompanied by reduction in dynamin-related proteins 1 (DRP1)-S616 phosphorylation. Furthermore, TRPC6 knockdown selectively decreased extracellular-signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Similar to TRPC6 knockdown, ERK1/2 inhibition by U0126 evoked mitochondrial elongation with diminished DRP1-S616 phosphorylation, and facilitated SE-induced DGC degeneration independent of seizure severity. These findings indicate that TRPC6 may regulate mitochondrial dynamics via ERK1/2-mediaed DRP1 activation, which would be involved in DGC invulnerability to SE. Therefore, TRPC6 will be an interesting and important therapeutic target for neurological diseases related to impaired mitochondrial dynamics.

ERK signaling pathway regulates sleep duration through activity-induced gene expression during wakefulness

Wakefulness is accompanied by experience-dependent synaptic plasticity and an increase in activity-regulated gene transcription. Wake-induced genes are certainly markers of neuronal activity and may also directly regulate the duration of and need for sleep. We stimulated murine cortical cultures with the neuromodulatory signals that are known to control wakefulness in the brain and found that norepinephrine alone or a mixture of these neuromodulators induced activity-regulated gene transcription. Pharmacological inhibition of the various signaling pathways involved in the regulation of gene expression indicated that the extracellular signal-regulated kinase (ERK) pathway is the principal one mediating the effects of waking neuromodulators on gene expression. In mice, ERK phosphorylation in the cortex increased and decreased with wakefulness and sleep. Whole-body or cortical neuron-specific deletion of Erk1 or Erk2 significantly increased the duration of wakefulness in mice, and pharmacological inhibition of ERK phosphorylation decreased sleep duration and increased the duration of wakefulness bouts. Thus, this signaling pathway, which is highly conserved from Drosophila to mammals, is a key pathway that links waking experience-induced neuronal gene expression to sleep duration and quality.

Attenuation of p38α MAPK stress response signaling delays the in vivo aging of skeletal muscle myofibers and progenitor cells

Functional competence and self-renewal of mammalian skeletal muscle myofibers and progenitor cells declines with age. Progression of the muscle aging phenotype involves the decline of juvenile protective factors i.e., proteins whose beneficial functions translate directly to the quality of life, and self-renewal of progenitor cells. These characteristics occur simultaneously with the age-associated increase of p38α stress response signaling. This suggests that the maintenance of low levels of p38α activity of juvenile tissues may delay or attenuate aging. We used the dominant negative haploinsufficient p38α mouse (DN-p38α^AF/+) to demonstrate that in vivo attenuation of p38α activity in the gastrocnemius of the aged mutant delays age-associated processes that include: a) the decline of the juvenile protective factors, BubR1, aldehyde dehydrogenase 1A (ALDH1A1), and aldehyde dehydrogenase 2 (ALDH2); b) attenuated expression of p16^Ink4a and p19^Arf tumor suppressor genes of the Cdkn2a locus; c) decreased levels of hydroxynonenal protein adducts, expression of COX2 and iNOS; d) decline of the senescent progenitor cell pool level and d) the loss of gastrocnemius muscle mass. We propose that elevated P-p38α activity promotes skeletal muscle aging and that the homeostasis of p38α impacts the maintenance of a beneficial healthspan.

Biased signaling initiated by agouti-related peptide through human melanocortin-3 and -4 receptors

The neural melanocortin receptors (MCRs), melanocortin-3 and -4 receptors (MC3R and MC4R), have been increasingly recognized as important regulators of energy homeostasis. The orexigenic agouti-related peptide (AgRP), initially identified as an endogenous antagonist for both neural MCRs, has been suggested to be a biased agonist of MC4R independent of its antagonizing effects. In the present study, we sought to determine the potential of AgRP to regulate the activation of intracellular kinases, including extracellular signal-regulated kinase 1 and 2 (ERK1/2), AKT and AMP-activated protein kinase (AMPK), through neural MCRs. We showed that AgRP acted as a biased agonist in human MC3R (hMC3R), decreasing cAMP activity of constitutively active mutant (F347A) hMC3R but stimulating ERK1/2 activation in both wide type and F347A hMC3Rs. AgRP-stimulated ERK1/2 phosphorylation through MC3R was abolished by protein kinase A (PKA) inhibitor H-89 but not Rp-cAMPS, whereas AgRP-initiated ERK1/2 activation through MC4R was inhibited by phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002. Both NDP-MSH and AgRP treatment induced significant AKT phosphorylation in GT1-7 cells but not in MC3R- or MC4R-transfected HEK293T cells. The phosphorylated AMPK levels in both GT1-7 cells and HERK293T cells transfected with neural MCRs were significantly decreased upon stimulation with NDP-MSH but not with AgRP. In summary, we provided novel data for AgRP-initiated multiple intracellular signaling pathways, demonstrating biased agonism of AgRP in both neural MCRs, leading to a better understanding of neural MCR pharmacology.

Metformin-induced energy deficiency leads to the inhibition of lipogenesis in prostate cancer cells

The deregulation of lipid metabolism is a hallmark of tumor cells, and elevated lipogenesis has been reported in prostate cancer. Metformin, a drug commonly prescribed for type II diabetes, displays antitumor properties. Here, we show that metformin inhibits lipogenesis in several prostate cancer cell lines. In LNCaP cells, this effect parallels the decrease of key lipogenic proteins: ACC (acetyl-CoA carboxylase), FASN (fatty acid synthase) and SREBP1c (sterol regulatory element binding protein-1c), whereas there is no modification in DU145 and PC3 cells. Despite the relatively high level of lipogenic proteins induced by the overexpression of a constitutively active form of SREBP1c or treatment with androgens, metformin is still able to inhibit lipogenesis. Metformin does not alter the concentration of malonyl-CoA (the fatty acid precursor), and it only slightly decreases the NADPH levels, which is a co-factor required for lipogenesis, in LNCaP. Finally, we show that the inhibitory effect of metformin on lipogenesis is primarily due to a cellular energy deficit. Metformin decreases ATP in a dose-dependent manner, and this diminution is significantly correlated with the inhibition of lipogenesis in LNCaP and DU145. Indeed, the effect of metformin is linked to changes in the ATP content rather than the regulation of protein expression. Our results describe a new mechanism of action for metformin on prostate cancer metabolism.

Genetic Analyses Reveal Functions for MAP2K3 and MAP2K6 in Mouse Testis Determination

Testis determination in mammals is initiated by expression of SRY in somatic cells of the embryonic gonad. Genetic analyses in the mouse have revealed a requirement for mitogen-activated protein kinase (MAPK) signaling in testis determination: targeted loss of the kinases MAP3K4 and p38 MAPK causes complete XY embryonic gonadal sex reversal. These kinases occupy positions at the top and bottom level, respectively, in the canonical threetier MAPK-signaling cascade: MAP3K, MAP2K, MAPK. To date, no role in sex determination has been attributed to a MAP2K, although such a function is predicted to exist. Here, we report roles for the kinases MAP2K3 and MAP2K6 in testis determination. C57BL/6J (B6) embryos lacking MAP2K3 exhibited no significant abnormalities of testis development, whilst those lacking MAP2K6 exhibited a minor delay in testis determination. Compound mutants lacking three out of four functional alleles at the two loci also exhibited delayed testis determination and transient ovotestis formation as a consequence, suggestive of partially redundant roles for these kinases in testis determination. Early lethality of double-knockout embryos precludes analysis of sexual development. To reveal their roles in testis determination more clearly, we generated Map2k mutant B6 embryos using a weaker Sry allele (Sry^AKR). Loss of Map2k3 on this highly sensitized background exacerbates ovotestis development, whilst loss of Map2k6 results in complete XY gonadal sex reversal associated with reduction of Sry expression at 11.25 days postcoitum. Our data suggest that MAP2K6 functions in mouse testis determination, via positive effects on Sry, and also indicate a minor role for MAP2K3.

Impact of the source and serial passaging of goat mesenchymal stem cells on osteogenic differentiation potential: implications for bone tissue engineering

BACKGROUND

Adult mesenchymal stem cells (MSCs) can be conveniently sampled from bone marrow, peripheral blood, muscle, adipose and connective tissue, harvested from various species, including, rodents, dogs, cats, horses, sheep, goats and human beings. The MSCs isolated from adult tissues vary in their morphological and functional properties. These variations are further complicated when cells are expanded by passaging in culture. These differences and changes in MSCs must be considered prior to their application in the clinic or in a basic research study. Goats are commonly used as animal models for bone tissue engineering to test the potential of stem cells for bone regeneration. As a result, goat MSCs isolated from bone marrow or adipose tissue should be evaluated using in vitro assays, prior to their application in a tissue engineering project.

RESULTS

In this study, we compared the stem cell properties of MSCs isolated from goat bone marrow and adipose tissue. We used quantitative and qualitative assays with a focus on osteogenesis, including, colony forming unit, rate of cell proliferation, tri-lineage differentiation and expression profiling of key signal transduction proteins to compare MSCs from low and high passages. Primary cultures generated from each source displayed the stem cell characteristics, with variations in their osteogenic potentials. Most importantly, low passaged bone marrow MSCs displayed a significantly higher and superior osteogenic potential, and hence, will be the preferred choice for bone tissue engineering in future in vivo experiments. In the bone marrow MSCs, this process is potentially mediated by the p38 MAPK pathway. On the other hand, osteogenic differentiation in the adipose tissue MSCs may involve the p44/42 MAPK pathway.

CONCLUSIONS

Based on these data, we can conclude that bone marrow and fat-derived MSCs undergo osteogenesis via two distinct signaling pathways. Even though the bone marrow MSCs are the preferred source for bone tissue engineering, the adipose tissue MSCs are an attractive alternative source and undergo osteo-differentiation differently from the bone marrow MSCs and hence, might require a cell-based enhancer/inducer to improve their osteogenic regenerative capacity.

Intracellular signaling pathway regulation of myelination and remyelination in the CNS

The restoration of myelin sheaths on demyelinated axons remains a major obstacle in the treatment of multiple sclerosis (MS). Currently approved therapies work by modulating the immune system to reduce the number and rate of lesion formation but are only partially effective since they are not able to restore lost myelin. In the healthy CNS, myelin continues to be generated throughout life and spontaneous remyelination occurs readily in response to insults. In patients with MS, however, remyelination eventually fails, at least in part as a result of a failure of oligodendrocyte precursor cell (OPC) differentiation and the subsequent production of new myelin. A better understanding of the molecular mechanisms and signaling pathways that drive the process of myelin sheath formation is therefore important in order to speed the development of novel therapeutics designed to target remyelination. Here we review data supporting critical roles for three highly conserved intracellular signaling pathways: Wnt/β-catenin, PI3K/AKT/mTOR, and ERK/MAPK in the regulation of OPC differentiation and myelination both during development and in remyelination. Potential points of crosstalk between the three pathways and important areas for future research are also discussed.

Selective Regulation of MAPK Signaling Mediates RANKL-dependent Osteoclast Differentiation

Different stimuli often activate the same intracellular signaling molecules but trigger distinct cell responses. We explored whether or not MAPK signaling induced by macrophage colony-stimulating factor (M-CSF), which is responsible for osteoclast proliferation, differs from that induced by receptor activator of NF-κB ligand (RANKL), which is essential for inducing osteoclast differentiation. The activation of MAPKs by M-CSF or RANKL differed in terms of the extent and duration of ERK, p38, and JNK phosphorylation as well as the isoform specificity of JNK phosphorylation. In particular, RANKL induced a second wave of MAPK activation coincident with the onset of osteoclast differentiation, whereas M-CSF triggered only a monophasic response. M-CSF was also able to trigger a full MAPK response on restimulation of cells earlier than was RANKL, representing that MAPK resensitization by M-CSF differs from that by RANKL. Furthermore, the adapter protein TRAF6 recruitment to the cytoplasmic tail of RANK in a submembrane compartment is specifically required for RANKL-induced activation of p38 MAPK, expression of osteoclastogenic transcription factors, and osteoclast differentiation, indicating that the switch from proliferation to differentiation in osteoclast precursors is dependent on p38 activation via the RANKL-RANK-TRAF6 axis. Our results suggest that selective control of MAPK signaling induced by M-CSF and by RANKL mediates the proliferation versus differentiation decision in osteoclast precursors.

Differential Activation of Mitogen-Activated Protein Kinases, ERK 1/2, p38(MAPK) and JNK p54/p46 During Postnatal Development of Rat Hippocampus

Mitogen-activated protein kinases (MAPKs) are a group of serine-threonine kinases, including p38(MAPK), ERK 1/2 and JNK p54/p46, activated by phosphorylation in response to extracellular stimuli. The early postnatal period is characterized by significant changes in brain structure as well as intracellular signaling. In the hippocampus MAPKs have been involved in the modulation of development and neural plasticity. However, the temporal profile of MAPK activation throughout the early postnatal development is incomplete. An understanding of this profile is important since slight changes in the activity of these enzymes, in response to environmental stress in specific developmental windows, might alter the course of development. The present study was undertaken to investigate the hippocampal differential activation of MAPK during postnatal period. MAPK activation and total content were evaluated by Western blotting of hippocampal tissue obtained from male Wistar rats at postnatal days (P) 1, 4, 7, 10, 14, 21, 30 and 60. The total content and phosphorylation of each MAPK was expressed as mean ± SEM and then calculates as a percentile compared to P1 (set at 100 %). The results showed: (1) phosphorylation peaks of p38(MAPK) at PN4 (p = 0.036) and PN10 to PN60; (2) phosphorylation of ERK1 and ERK2 were increased with age (ERK1 p = 0.0000005 and ERK2 p = 0.003); (3) phosphorylation profile of JNK p54/p46 was not changed during the period analyzed (JNKp56 p = 0.716 and JNKp46 p = 0.192). Therefore, the activity profile of ERK 1/2 and p38(MAPK) during postnatal development of rat hippocampus are differentially regulated. Our results demonstrate that ERK 1/2 and p38(MAPK) are dynamically regulated during postnatal neurodevelopment, suggesting temporal correlation of MAPK activity with critical periods when programmed cell death and synaptogenesis are occurring. This suggests an important role for these MAPKs in postnatal development of rat hippocampus.

A requirement of serotonergic p38α mitogen-activated protein kinase for peripheral immune system activation of CNS serotonin uptake and serotonin-linked behaviors

Alterations in central serotonin (5-hydroxytryptamine, 5-HT) neurotransmission and peripheral immune activation have been linked to multiple neuropsychiatric disorders, including depression, schizophrenia and autism. The antidepressant-sensitive 5-HT transporter (SERT, SLC6A4), a critical determinant of synaptic 5-HT inactivation, can be regulated by pro-inflammatory cytokine signaling. Systemic innate immune system activation via intraperitoneal lipopolysaccharide (LPS) injection rapidly elevates brain SERT activity and 5-HT clearance. Moreover, the pro-inflammatory cytokine interleukin (IL)-1β rapidly stimulates SERT activity in raphe nerve terminal preparations ex vivo, effects that are attenuated by pharmacological p38 MAPK inhibition. To establish a role of serotonergic p38α MAPK signaling in LPS/IL-1β-induced SERT regulation and attendant behavioral responses, we pursued studies in mice that afford conditional elimination of p38α MAPK in 5-HT neurons (p38α(5HT-)). We found p38α(5HT-) and control (p38α(5HT+)) littermates to be indistinguishable in viability and growth and to express equivalent levels of SERT protein and synaptosomal 5-HT transport activity. Consistent with pharmacological studies, however, IL-1β fails to increase SERT activity in midbrain synaptosomes prepared from p38α(5HT-) animals. Moreover, although LPS elevated plasma corticosterone and central/peripheral pro-inflammatory cytokines in p38α(5HT-) animals, elevations in midbrain SERT activity were absent nor were changes in depressive and anxiety-like behaviors observed. Our studies support an obligate role of p38α MAPK signaling in 5-HT neurons for the translation of immune activation to SERT regulation and 5-HT-modulated behaviors.

Vascular endothelial growth factor A: just one of multiple mechanisms for sex-specific vascular development within the testis?

Testis development from an indifferent gonad is a critical step in embryogenesis. A hallmark of testis differentiation is sex-specific vascularization that occurs as endothelial cells migrate from the adjacent mesonephros into the testis to surround Sertoli-germ cell aggregates and induce seminiferous cord formation. Many in vitro experiments have demonstrated that vascular endothelial growth factor A (VEGFA) is a critical regulator of this process. Both inhibitors to VEGFA signal transduction and excess VEGFA isoforms in testis organ cultures impaired vascular development and seminiferous cord formation. However, in vivo models using mice which selectively eliminated all VEGFA isoforms: in Sertoli and germ cells (pDmrt1-Cre;Vegfa(-/-)); Sertoli and Leydig cells (Amhr2-Cre;Vegfa(-/-)) or Sertoli cells (Amh-Cre;Vegfa(-/-) and Sry-Cre;Vegfa(-/-)) displayed testes with observably normal cords and vasculature at postnatal day 0 and onwards. Embryonic testis development may be delayed in these mice; however, the postnatal data indicate that VEGFA isoforms secreted from Sertoli, Leydig or germ cells are not required for testis morphogenesis within the mouse. A Vegfa signal transduction array was employed on postnatal testes from Sry-Cre;Vegfa(-/-) versus controls. Ptgs1 (Cox1) was the only upregulated gene (fivefold). COX1 stimulates angiogenesis and upregulates, VEGFA, Prostaglandin E2 (PGE2) and PGD2. Thus, other gene pathways may compensate for VEGFA loss, similar to multiple independent mechanisms to maintain SOX9 expression. Multiple independent mechanism that induce vascular development in the testis may contribute to and safeguard the sex-specific vasculature development responsible for inducing seminiferous cord formation, thus ensuring appropriate testis morphogenesis in the male.

p38 MAP kinases in the heart

p38 kinases are members of the mitogen-activated protein kinases (MAPK) with established contribution to a wide range of signaling pathways and different biological processes. The prototypic p38 MAPK, p38α was originally identified as an essential signaling kinase for inflammatory cytokine production Extensive studies have now revealed that p38s have critical roles in many different tissues far beyond immune regulation and inflammatory responses. In this review, we will focus on the structure and molecular biology of p38s, and their specific roles in heart, especially regarding myocyte proliferation, apoptosis, and hypertrophic responses.

Phenotypic and evolutionary implications of modulating the ERK-MAPK cascade using the dentition as a model

The question of phenotypic convergence across a signalling pathway has important implications for both developmental and evolutionary biology. The ERK-MAPK cascade is known to play a central role in dental development, but the relative roles of its components remain unknown. Here we investigate the diversity of dental phenotypes in Spry2^−/−, Spry4^−/−, and Rsk2^−/Y mice, including the incidence of extra teeth, which were lost in the mouse lineage 45 million years ago (Ma). In addition, Sprouty-specific anomalies mimic a phenotype that is absent in extant mice but present in mouse ancestors prior to 9 Ma. Although the mutant lines studied display convergent phenotypes, each gene has a specific role in tooth number determination and crown patterning. The similarities found between teeth in fossils and mutants highlight the pivotal role of the ERK-MAPK cascade during the evolution of the dentition in rodents.

The logic of communication: roles for mobile transcription factors in plants

Mobile transcription factors play many roles in plant development. Here, we compare the use of mobile transcription factors as signals with some canonical signal transduction processes in prokaryotes and eukaryotes. After an initial survey, we focus on the SHORT-ROOT pathway in Arabidopsis roots to show that, despite the simplicity of the concept of mobile transcription factor signalling, many lines of evidence reveal a surprising complexity in control mechanisms linked to this process. We argue that these controls bestow precision, robustness, and versatility on mobile transcription factor signalling.

Soy isoflavones in nutritionally relevant amounts have varied nutrigenomic effects on adipose tissue

Soy consumption has been suggested to afford protection from cardiovascular disease (CVD). Indeed, accumulated albeit controversial evidence suggests that daily consumption of ≥25 g of soy protein with its associated phytochemicals intact can improve lipid profiles in hypercholesterolemic humans. However, the belief that soy foods and supplements positively impact human health has become increasingly controversial among the general public because of the reported estrogenic activities of soy isoflavones. In this study, we investigated the nutrigenomic actions of soy isoflavones (in nutritionally-relevant amounts) with a specific focus on the adipose tissue, due to its pivotal role in cardiometabolism. Young C57BL/6 mice were maintained for eight weeks under two different diet regimes: (1) purified control diet; or (2) purified control diet supplemented with 0.45 g% soybean dry purified extract (a genistein/daidzein mix). Soy isoflavones increased plasma total cholesterol concentrations and decreased triglyceride ones. Circulating leptin levels was also increased by soy consumption. Differentially expressed genes in adipose tissue were classified according to their role(s) in cellular or metabolic pathways. Our data show that soy isoflavones, administered in nutritionally-relevant amounts, have diverse nutrigenomic effects on adipose tissue. Taking into account the moderate average exposure to such molecules, their impact on cardiovascular health needs to be further investigated to resolve the issue of whether soy consumption does indeed increase or decrease cardiovascular risk.

Chronic activation of CB2 cannabinoid receptors in the hippocampus increases excitatory synaptic transmission

KEY POINTS

The effects of cannabinoids are primarily mediated by two types of cannabinoid receptors, CB1 receptors in the nervous system and CB2 receptors in the immune system. Recent evidence indicates that CB2 receptors are also widely expressed in the brain and involved in neuropsychiatric functions, such as schizophrenia-like behaviours, anxiety, memory, vomiting and pain. The cellular mechanisms by which CB2 receptors regulate neuronal functions are unknown. We show that chronic activation of CB2 receptors in the hippocampus for 7-10 days increases excitatory synaptic transmission, whereas short-term activation of CB2 receptors has little effect on synaptic activity. This study reveals a novel role of CB2 receptors in the brain, which is clearly distinct from that of CB1 receptors, and thus, will help us to understand better the diverse effects of cannabinoids in the nervous system.

ABSTRACT

The roles of CB1 cannabinoid receptors in regulating neuronal activity have been extensively characterized. Although early studies show that CB1 receptors are present in the nervous system and CB2 cannabinoid receptors are in the immune system, recent evidence indicates that CB2 receptors are also expressed in the brain. Activation or blockade of CB2 receptors in vivo induces neuropsychiatric effects, but the cellular mechanisms of CB2 receptor function are unclear. The aim of this study is to determine how activation of CB2 receptors present in the hippocampus regulates synaptic function. Here, we show that when organotypic cultures of rodent hippocampal slices were treated with a CB2 receptor agonist (JWH133 or GP1a) for 7-10 days, quantal glutamate release became more frequent and spine density was increased via extracellular signal-regulated kinases. Chronic intraperitoneal injection of JWH133 into mice also increased excitatory synaptic transmission. These effects were blocked by a CB2 receptor antagonist (SR144528) or absent from hippocampal slices of CB2 receptor knock-out mice. This study reveals a novel cellular function of CB2 cannabinoid receptors in the hippocampus and provides insights into how cannabinoid receptor subtypes diversify the roles of cannabinoids in the brain.

Oxygen- and temperature-dependent expression of survival protein kinases in crucian carp (Carassius carassius) heart and brain

Living without oxygen is limited to very few vertebrates, one species being the fresh water fish crucian carp (Carassius carassius), which can survive months of anoxia at low temperatures. Mammalian heart and brain are particularly intolerant to oxygen deprivation, yet these organs can be conditioned to display increased resistance, possibly due to activation of several protein kinases. We hypothesized increased phosphorylation status of these kinases in hypoxic and anoxic crucian carp heart and brain. Moreover, we wanted to investigate whether the kinases showing the strongest phosphorylation during hypoxia/anoxia, ERK 1/2, p38-MAPK, JNK, PKCε, and PKCδ, also had increased expression and phosphorylation at cold temperatures, to better cope with the anoxic periods during winter. We found small differences in the phosphorylation status of ERK 1/2, p38-MAPK, JNK, PKCε, and PKCδ during 10 days of severe hypoxia in both heart and brain (0.3 mg O₂/l) and varying responses to reoxygenation. In contrast, 7 days of anoxia (<0.01 mg O₂/l) markedly increased phosphorylation of ERK 1/2, p38-MAPK, JNK in the heart, and p38-MAPK and PKCε in the brain. Similarly, varying acclimation temperature between 4, 10 and 20°C induced large changes in phosphorylation status. Total protein expression in heart and brain neither changed during different oxygen regimes nor with different acclimation temperatures, except for ERK 1/2, which slightly decreased in the heart at 4°C compared with 20°C. A phylogenetic analysis confirmed that these protein kinases are evolutionarily conserved across a wide range of vertebrate species. Our findings indicate important roles of several protein kinases during oxygen deprivation.

A comprehensive transcriptomic analysis of infant and adult mouse ovary

Ovary development is a complex process involving numerous genes. A well-developed ovary is essential for females to keep fertility and reproduce offspring. In order to gain a better insight into the molecular mechanisms related to the process of mammalian ovary development, we performed a comparative transcriptomic analysis on ovaries isolated from infant and adult mice by using next-generation sequencing technology (SOLiD). We identified 15,454 and 16,646 transcriptionally active genes at the infant and adult stage, respectively. Among these genes, we also identified 7021 differentially expressed genes. Our analysis suggests that, in general, the adult ovary has a higher level of transcriptomic activity. However, it appears that genes related to primordial follicle development, such as those encoding Figla and Nobox, are more active in the infant ovary, whereas expression of genes vital for follicle development, such as Gdf9, Bmp4 and Bmp15, is upregulated in the adult. These data suggest a dynamic shift in gene expression during ovary development and it is apparent that these changes function to facilitate follicle maturation, when additional functional gene studies are considered. Furthermore, our investigation has also revealed several important functional pathways, such as apoptosis, MAPK and steroid biosynthesis, that appear to be much more active in the adult ovary compared to those of the infant. These findings will provide a solid foundation for future studies on ovary development in mice and other mammals and help to expand our understanding of the complex molecular and cellular events that occur during postnatal ovary development.

Shock wave treatment enhances cell proliferation and improves wound healing by ATP release-coupled extracellular signal-regulated kinase (ERK) activation

Shock wave treatment accelerates impaired wound healing in diverse clinical situations. However, the mechanisms underlying the beneficial effects of shock waves have not yet been fully revealed. Because cell proliferation is a major requirement in the wound healing cascade, we used in vitro studies and an in vivo wound healing model to study whether shock wave treatment influences proliferation by altering major extracellular factors and signaling pathways involved in cell proliferation. We identified extracellular ATP, released in an energy- and pulse number-dependent manner, as a trigger of the biological effects of shock wave treatment. Shock wave treatment induced ATP release, increased Erk1/2 and p38 MAPK activation, and enhanced proliferation in three different cell types (C3H10T1/2 murine mesenchymal progenitor cells, primary human adipose tissue-derived stem cells, and a human Jurkat T cell line) in vitro. Purinergic signaling-induced Erk1/2 activation was found to be essential for this proliferative effect, which was further confirmed by in vivo studies in a rat wound healing model where shock wave treatment induced proliferation and increased wound healing in an Erk1/2-dependent fashion. In summary, this report demonstrates that shock wave treatment triggers release of cellular ATP, which subsequently activates purinergic receptors and finally enhances proliferation in vitro and in vivo via downstream Erk1/2 signaling. In conclusion, our findings shed further light on the molecular mechanisms by which shock wave treatment exerts its beneficial effects. These findings could help to improve the clinical use of shock wave treatment for wound healing.