Piceatannol selectively inhibited the JNK3 enzyme and augmented apoptosis through inhibition of Bcl-2/Cyt-c/caspase-dependent pathways in the oxygen-glucose deprived SHSY-5Y cell lines: In silico and in vitro study.

JNK3, a neuronal kinase activated by stress, plays a role in stress-induced apoptosis, leading to neuronal cell death following cerebral ischemia. This study investigates the neuroprotective effects of piceatannol (PCT) in SHSY-5Y neuroblastoma cells after hypoxic injury and its interaction with JNK3. We analyzed the crystal coordinates, interaction energies, and amino acid interactions to determine PCT's selectivity for JNK3. The electrostatic potential was computed using density functional theory, while molecular dynamics assessed the stability and structural consistency of the JNK3-PCT complex. We used SP600125 (SP6), a JNK3 inhibitor, as a reference compound. Additionally, we performed cell-free JNK 1, 2, and 3 kinase assays to evaluate the isoform selectivity of PCT. Cytotoxicity and cell viability were determined by an MTT test. To assess apoptosis, we used acridine orange/ethidium bromide dual fluorescent labeling and ANNEXIN A5-FITC flow cytometry. Western blot was used to evaluate the attenuation of JNK3 and apoptotic proteins. In silico studies revealed a stronger binding affinity between PCT and JNK3 compared to JNK1 and JNK2, which was further supported by the in vitro kinase assay. PCT-treated cells exhibited a decrease in Cyt-c and caspase-3 expression and an increase in Bcl-2 level, compared to hypoxic control (p < .001). PCT also demonstrated superior efficacy over SP6 in inhibiting JNK3 phosphorylation (p < .001). Furthermore, PCT significantly increased the expression of neuronal genes, including NgN1, neuroD2, and survivin (p < .001). In conclusion, PCT is a potential JNK3 inhibitor, since it inhibited phosphorylation and the Bcl-2/Cyt-C/caspase-3-dependent apoptotic pathway after ischemic/hypoxic insult.

Genetic deletion of c-Jun amino-terminal kinase 3 (JNK3) modestly increases disease severity in a mouse model of multiple sclerosis.

The c-Jun amino terminal kinases (JNKs) regulate transcription, and studies suggest they contribute to neuropathology in the EAE model of MS. To examine the role of the JNK3 isoform, we compared EAE in JNK3 null mice to wild type (WT) littermates. Although disease severity was similar in female mice, in male JNK3 null mice the day of onset and time to reach 100% incidence occurred sooner, and disease severity was increased. While glial activation in spinal cord was similar, white matter lesions were increased in JNK3 null mice. These results suggest JNK3 normally limits EAE disease in a sex-dependent manner.

Time series RNA-seq analysis identifies MAPK10 as a critical gene in diabetes mellitus-induced atrial fibrillation in mice.

Atrial fibrillation (AF) is a major complication of type 2 diabetes mellitus (T2DM) and plays critical roles in the pathogenesis of atrial remodeling. However, the differentially expressed genes in atria during the development of AF induced by hyperglycemia have rarely been reported. Here, we showed time-dependent increased AF incidence and duration, atrial enlargement, inflammation, fibrosis, conduction time and action potential duration in db/db mice, a model of T2DM. RNA sequencing analysis showed that 2256 genes were differentially expressed in the atria at 12, 14 and 16 weeks. Gene Ontology analysis showed that these genes participate primarily in cell adhesion, cellular response to interferon-beta, immune system process, positive regulation of cell migration, ion transport and cellular response to interferon-gamma. Analysis of significant pathways revealed the IL-17 signaling pathway, TNF signaling pathway, MAPK signaling pathway, chemokine signaling pathway, and cAMP receptor signaling. Additionally, these differentially expressed genes were classified into 50 profiles by hierarchical clustering analysis. Twelve of these profiles were significant and comprised 1115 genes. Gene coexpression network analysis identified that mitogen-activated protein kinase 10 (MAPK10) was localized in the core of the gene network and was the most highly expressed gene at different time points. Knockdown of MAPK10 markedly attenuated DM-induced AF incidence, atrial inflammation, fibrosis, electrical disorder and apoptosis in db/db mice. In summary, the present findings revealed that many genes are involved in DM-induced AF and that MAPK10 plays a central role in this disease, indicating that strategies targeting MAPK10 may represent a potential therapeutic approach to treat DM-induced AF.

The expression profile of miR-222b-5p/MAPK10 in spleens of SPF chickens infected with REV-SNV at 28-42 dpi.

Reticuloendotheliosis virus (REV) is an avian oncogenic retrovirus that causes atrophy of immune organs, such as the spleen, thymus, and bursa of Fabricius, leading to severe immunosuppression. However, there is limited information describing the genes or microRNAs (miRNAs) that play a role in replicating REV-spleen necrosis virus (SNV). Our previous miRNA and RNA sequencing data showed that the expression of gga-miR-222b-5p was significantly upregulated in REV-SNV-infected chicken spleens of 7, 14, and 21 dpi compared to non-infected chicken spleens, but mitogen-activated protein kinase 10 (MAPK10), which is related to innate immunity, had the opposite expression pattern. To understand chicken cellular miRNA function in the virus-host interactions during REV infection, we used quantitative reverse transcription PCR (qRT-PCR) to determine whether the expression of gga-miR-222b-5p and MAPK10 in the spleen of specific-pathogen-free chickens at 28, 35, and 42 dpi was consistent with the first 3 time points, and dual-luciferase reporter assay was used to determine the targeting relationship between gga-miR-222b-5p and MAPK10. Results show that MAPK10 was downregulated at all 3 time points; however, significant difference (p⟨0.01) was noted only at 35 dpi. Moreover, the expression of gga-miR-222b-5p was upregulated; however, significant difference (p⟨0.01) was observed only at 28 and 35 dpi. A dual-luciferase reporter assay showed that MAPK10 is a direct target of gga-miR-222b-5p. This study suggests that gga-miR-222b-5p may target MAPK10 to promote the REV-SNV-induced tumorigenesis via the RLRs signaling pathway.

Genetic variants in MAPK10 modify renal cell carcinoma susceptibility and clinical outcomes.

AIMS: The mitogen-activated protein kinase (MAPK) cascades integrate various upstream signals to regulate many cellular functions, including proliferation, differentiation, and survival. Dysregulation of these pathways has been implicated in the occurrence and progression of a variety of cancers. MAIN METHODS: This study aimed to assess the association of 192 single nucleotide polymorphisms in 22 MAPK cascade genes with renal cell carcinoma (RCC) risk and survival in 312 patients and 318 controls. KEY FINDINGS: After multiple testing correction and multivariate analysis, the minor T allele of MAPK10 rs12648265 remained associated with a lower risk of RCC (adjusted odds ratio 0.64, 95% confidence interval 0.50-0.82, P = 0.000426) and metastasis (adjusted hazard ratio 0.50, 95% confidence interval 0.30-0.82, P = 0.006). Presence of the rs12648265 T allele demonstrated a trend towards being associated with increased MAPK10 expression, and meta-analysis of four RCC datasets indicated that high MAPK10 expression is associated with a favourable prognosis. Furthermore, activation of MAPK10 by the potent agonist anisomycin inhibited RCC cell growth in vitro, suggesting an involvement of MAPK10 in RCC progression. SIGNIFICANCE: In conclusion, MAPK10 may be a meaningful biomarker and a potential therapeutic target in RCC.

The Map3k12 (Dlk)/JNK3 signaling pathway is required for pancreatic beta-cell proliferation during postnatal development.

Unveiling the key pathways underlying postnatal beta-cell proliferation can be instrumental to decipher the mechanisms of beta-cell mass plasticity to increased physiological demand of insulin during weight gain and pregnancy. Using transcriptome and global Serine Threonine Kinase activity (STK) analyses of islets from newborn (10 days old) and adult rats, we found that highly proliferative neonatal rat islet cells display a substantially elevated activity of the mitogen activated protein 3 kinase 12, also called dual leucine zipper-bearing kinase (Dlk). As a key upstream component of the c-Jun amino terminal kinase (Jnk) pathway, Dlk overexpression was associated with increased Jnk3 activity and was mainly localized in the beta-cell cytoplasm. We provide the evidence that Dlk associates with and activates Jnk3, and that this cascade stimulates the expression of Ccnd1 and Ccnd2, two essential cyclins controlling postnatal beta-cell replication. Silencing of Dlk or of Jnk3 in neonatal islet cells dramatically hampered primary beta-cell replication and the expression of the two cyclins. Moreover, the expression of Dlk, Jnk3, Ccnd1 and Ccnd2 was induced in high replicative islet beta cells from ob/ob mice during weight gain, and from pregnant female rats. In human islets from non-diabetic obese individuals, DLK expression was also cytoplasmic and the rise of the mRNA level was associated with an increase of JNK3, CCND1 and CCND2 mRNA levels, when compared to islets from lean and obese patients with diabetes. In conclusion, we find that activation of Jnk3 signalling by Dlk could be a key mechanism for adapting islet beta-cell mass during postnatal development and weight gain.

Accelerating bone healing in vivo by harnessing the age-altered activation of c-Jun N-terminal kinase 3.

We have recently demonstrated that c-Jun N-terminal kinase 3 (JNK3) is a key modulator of the enhanced osteogenic potential of stem cells derived from children when compared to those derived from adults. In this study, we formulated a JNK3-activator nanoparticle (JNK3*) that recapitulates the immense osteogenic potential of juvenile cells in adult stem cells by facilitating JNK3 activation. Moreover, we aimed to functionalize a collagen-based scaffold by incorporating the JNK3* in order to develop an advanced platform capable of accelerating bone healing by recruitment of host stem cells. Our data, in vitro and in vivo, demonstrated that the immense osteogenic potential of juvenile cells could be recapitulated in adult stem cells by facilitating JNK3 activation. Moreover, our results revealed that the JNK3* functionalized 3D scaffold induced the fastest bone healing and greatest blood vessel infiltration when implanted in critical-size rat calvarial defects in vivo. JNK3*scaffold fastest bone healing in vivo was associated with its capacity to recruit host stem cells to the site of injury and promote angiogenic-osteogenic coupling (e.g. Vegfa, Tie1, Runx2, Alp and Igf2 upregulation). In summary, this study has demonstrated the potential of harnessing knowledge of age-altered stem cell mechanobiology in order to develop a materials-based functionalization approach for the repair of large tissue defects.

JNK3 as Therapeutic Target and Biomarker in Neurodegenerative and Neurodevelopmental Brain Diseases.

The c-Jun N-terminal kinase 3 (JNK3) is the JNK isoform mainly expressed in the brain. It is the most responsive to many stress stimuli in the central nervous system from ischemia to Aß oligomers toxicity. JNK3 activity is spatial and temporal organized by its scaffold protein, in particular JIP-1 and ß-arrestin-2, which play a crucial role in regulating different cellular functions in different cellular districts. Extensive evidence has highlighted the possibility of exploiting these adaptors to interfere with JNK3 signaling in order to block its action. JNK plays a key role in the first neurodegenerative event, the perturbation of physiological synapse structure and function, known as synaptic dysfunction. Importantly, this is a common mechanism in many different brain pathologies. Synaptic dysfunction and spine loss have been reported to be pharmacologically reversible, opening new therapeutic directions in brain diseases. Being JNK3-detectable at the peripheral level, it could be used as a disease biomarker with the ultimate aim of allowing an early diagnosis of neurodegenerative and neurodevelopment diseases in a still prodromal phase.

Biological Properties of JNK3 and Its Function in Neurons, Astrocytes, Pancreatic ß-Cells and Cardiovascular Cells.

JNK is a protein kinase, which induces transactivation of c-jun. The three isoforms of JNK, JNK1, JNK2, and JNK3, are encoded by three distinct genes. JNK1 and JNK2 are expressed ubiquitously throughout the body. By contrast, the expression of JNK3 is limited and observed mainly in the brain, heart, and testes. Concerning the biological properties of JNKs, the contribution of upstream regulators and scaffold proteins plays an important role in the activation of JNKs. Since JNK signaling has been described as a form of stress-response signaling, the contribution of JNK3 to pathophysiological events, such as stress response or cell death including apoptosis, has been well studied. However, JNK3 also regulates the physiological functions of neurons and non-neuronal cells, such as development, regeneration, and differentiation/reprogramming. In this review, we shed light on the physiological functions of JNK3. In addition, we summarize recent advances in the knowledge regarding interactions between JNK3 and cellular reprogramming.

Circ_0000515 drives the progression of hepatocellular carcinoma by regulating MAPK10.

OBJECTIVE: To explore the expression pattern and clinical significance of circ_0000515 in hepatocellular carcinoma (HCC), as well as the molecular mechanism. PATIENTS AND METHODS: Fifty HCC patients were recruited, and their cancer tissues and adjacent normal ones were collected for detecting the differential expression of circ_0000515. The relationship between circ_0000515 and clinical parameters in HCC patients was analyzed. Circ_0000515 knockdown model was generated by lentivirus transfection in Hep3B and MHCC88H cells that were highly expressed with circ_0000515. Regulatory effects of circ_0000515 on phenotypes of Hep3B and MHCC88H cells were examined by Cell Counting Kit-8 (CCK-8) and transwell assay. Target gene of circ_0000515 was verified by Dual-Luciferase reporter assay, and its involvement in HCC progression was detected by rescue experiments. In vivo xenograft model was generated in nude mice aiming to elucidate the role of circ_0000515 in regulating HCC growth. RESULTS: Circ_0000515 was highly expressed in HCC tissues and cell lines. High level of circ_0000515 predicted advanced stage, high incidence of lymphatic metastasis, and low disease-free survival and overall survival in HCC. Knockdown of circ_0000515 attenuated proliferative and migratory abilities in Hep3B and MHCC88H cells. MAPK10, as the target gene binding circ_0000515, was negatively regulated by circ_0000515. Rescue experiments and in vivo xenograft model both indicated that circ_0000515 aggravated the malignant progression of HCC by targeting MAPK10. CONCLUSIONS: Circ_0000515 is upregulated in HCC tissues and cell lines. It can be used for predicting tumor staging, lymphatic metastasis, and prognosis in HCC. Circ_0000515 aggravates the malignant progression of HCC by downregulating MAPK10.

MicroRNA-4516-mediated regulation of MAPK10 relies on 3' UTR cis-acting variants and contributes to the altered risk of Hirschsprung disease.

BACKGROUND: Hirschsprung disease (HSCR) is a life-threatening congenital disorder in which the enteric nervous system is completely missing from the distal gut. Recent studies have shown that miR-4516 markedly inhibits cell migration, and as one of its potential targets, MAPK10 functions as a modifier for developing HSCR. We thus aimed to evaluate the role of miR-4516 and MAPK10 in HSCR and how they contribute to the pathogenesis of HSCR. METHODS: We examined 13 genetic variants using the MassArray system in a case-control study (n=1015). We further investigated miR-4516-mediated regulation of MAPK10 in HSCR cases and human neural cells, the effects of cis-acting elements in MAPK10 on miR-4516-mediated modulation and cell migration process. RESULTS: Three positive 3' UTR variants in MAPK10 were associated with altered HSCR susceptibility. We also showed that miR-4516 directly regulates MAPK10 expression, and this regulatory mechanism is significantly affected by the 3' UTR cis-acting elements of MAPK10. In addition, knock-down of MAPK10 rescued the effect of miR-4516 on the migration of human neural cells. CONCLUSION: Our findings indicate a key role of miR-4516 and its direct target MAPK10 in HSCR risk, and highlight the general importance of cis- and posttranscriptional modulation for HSCR pathogenesis.

LmjMAPK10 offers protection against Leishmania donovani infection.

AIMS: This study aimed at evaluating the DNA vaccination efficacy of Leishmania major-derived MAPK10 against Leishmania donovani infection. METHODS AND RESULTS: MAPK10 is one of the 15 mitogen-activated protein kinases (MAPKs) of Leishmania major. Herein, we expressed the gene through a mammalian vector and tested whether priming with this gene would offer protection against L donovani infection. We report that LmjMAPK10 DNA vaccination using a mammalian expression vector significantly reduces the parasite burden. The protection is accompanied by host-protective T-cell functions, TH 1-type cytokines and elevated leishmanial antigen-specific IgG2a isotype response. T-cell response to the L donovani/challenge infection is associated with increase in IL-12 and IFN-γ, but reduced IL-10 and IL-4 production. CONCLUSIONS: LmjMAPK10 is cross-protective against L donovani infection.

Neural JNK3 regulates blood flow recovery after hindlimb ischemia in mice via an Egr1/Creb1 axis.

Diseases related to impaired blood flow such as peripheral artery disease (PAD) impact nearly 10 million people in the United States alone, yet patients with clinical manifestations of PAD (e.g., claudication and limb ischemia) have limited treatment options. In ischemic tissues, stress kinases such as c-Jun N-terminal kinases (JNKs), are activated. Here, we show that inhibition of the JNK3 (Mapk10) in the neural compartment strikingly potentiates blood flow recovery from mouse hindlimb ischemia. JNK3 deficiency leads to upregulation of growth factors such as Vegfa, Pdgfb, Pgf, Hbegf and Tgfb3 in ischemic muscle by activation of the transcription factors Egr1/Creb1. JNK3 acts through Forkhead box O3 (Foxo3a) to suppress the activity of Egr1/Creb1 transcription regulators in vitro. In JNK3-deficient cells, Foxo3a is suppressed which leads to Egr1/Creb1 activation and upregulation of downstream growth factors. Collectively, these data suggest that the JNK3-Foxo3a-Egr1/Creb1 axis coordinates the vascular remodeling response in peripheral ischemia.

Structural Mechanism of the Arrestin-3/JNK3 Interaction.

Arrestins, in addition to desensitizing GPCR-induced G protein activation, also mediate G protein-independent signaling by interacting with various signaling proteins. Among these, arrestins regulate MAPK signal transduction by scaffolding mitogen-activated protein kinase (MAPK) signaling components such as MAPKKK, MAPKK, and MAPK. In this study, we investigated the binding mode and interfaces between arrestin-3 and JNK3 using hydrogen/deuterium exchange mass spectrometry, 19F-NMR, and tryptophan-induced Atto 655 fluorescence-quenching techniques. Results suggested that the ß1 strand of arrestin-3 is the major and potentially only interaction site with JNK3. The results also suggested that C-lobe regions near the activation loop of JNK3 form the potential binding interface, which is variable depending on the ATP binding status. Because the ß1 strand of arrestin-3 is buried by the C-terminal strand in its basal state, C-terminal truncation (i.e., pre-activation) of arrestin-3 facilitates the arrestin-3/JNK3 interaction.

Bioinformatics analysis to reveal the key genes related to obstructive sleep apnea.

PURPOSE: Obstructive sleep apnea (OSA) is induced by obstruction of the upper airway, which can raise multiple health risks. This study is designed to reveal the key genes involved in OSA. METHODS: GSE38792 was extracted from Gene Expression Omnibus database, including ten visceral adipose tissues from OSA patients and eight visceral adipose tissues from normal controls. Differential expression analysis was conducted using limma package, and then the functions of the differentially expressed genes (DEGs) were analyzed using DAVID database, followed by protein-protein interaction (PPI) network, and integrated regulatory network analysis was performed using Cytoscape software. RESULTS: A total of 368 DEGs (176 upregulated and 192 downregulated) were identified in OSA samples. Epstein-Barr virus infection (involving IL10RB, MAPK9, and MAPK10) and olfactory transduction were the main pathways separately enriched for the upregulated genes and the downregulated genes. After the PPI network was built, the top ten network nodes (such as TXN) were selected according to node degrees. Two significant PPI network modules were identified. Moreover, the integrated regulatory network was constructed. CONCLUSION: IL10RB, MAPK9, MAPK10, and TXN might function in the pathogenesis of OSA.

APP upregulation contributes to retinal ganglion cell degeneration via JNK3.

Axonal injury is a common feature of central nervous system insults. Upregulation of amyloid precursor protein (APP) is observed following central nervous system neurotrauma and is regarded as a marker of central nervous system axonal injury. However, the underlying mechanism by which APP mediates neuronal death remains to be elucidated. Here, we used mouse optic nerve axotomy (ONA) to model central nervous system axonal injury replicating aspects of retinal ganglion cell (RGC) death in optic neuropathies. APP and APP intracellular domain (AICD) were upregulated in retina after ONA and APP knockout reduced Tuj1+ RGC loss. Pathway analysis of microarray data combined with chromatin immunoprecipitation and a luciferase reporter assay demonstrated that AICD interacts with the JNK3 gene locus and regulates JNK3 expression. Moreover, JNK3 was found to be upregulated after ONA and to contribute to Tuj1+ RGC death. APP knockout reduced the ONA-induced enhanced expression of JNK3 and phosphorylated JNK (pJNK). Gamma-secretase inhibitors prevented production of AICD, reduced JNK3 and pJNK expression similarly, and protected Tuj1+ RGCs from ONA-induced cell death. Together these data indicate that ONA induces APP expression and that gamma-secretase cleavage of APP releases AICD, which upregulates JNK3 leading to RGC death. This pathway may be a novel target for neuronal protection in optic neuropathies and other forms of neurotrauma.

KLF9 and JNK3 Interact to Suppress Axon Regeneration in the Adult CNS.

Neurons in the adult mammalian CNS decrease in intrinsic axon growth capacity during development in concert with changes in Krüppel-like transcription factors (KLFs). KLFs regulate axon growth in CNS neurons including retinal ganglion cells (RGCs). Here, we found that knock-down of KLF9, an axon growth suppressor that is normally upregulated 250-fold in RGC development, promotes long-distance optic nerve regeneration in adult rats of both sexes. We identified a novel binding partner, MAPK10/JNK3 kinase, and found that JNK3 (c-Jun N-terminal kinase 3) is critical for KLF9's axon-growth-suppressive activity. Interfering with a JNK3-binding domain or mutating two newly discovered serine phosphorylation acceptor sites, Ser106 and Ser110, effectively abolished KLF9's neurite growth suppression in vitro and promoted axon regeneration in vivo These findings demonstrate a novel, physiologic role for the interaction of KLF9 and JNK3 in regenerative failure in the optic nerve and suggest new therapeutic strategies to promote axon regeneration in the adult CNS.SIGNIFICANCE STATEMENT Injured CNS nerves fail to regenerate spontaneously. Promoting intrinsic axon growth capacity has been a major challenge in the field. Here, we demonstrate that knocking down Krüppel-like transcription factor 9 (KLF9) via shRNA promotes long-distance axon regeneration after optic nerve injury and uncover a novel and important KLF9-JNK3 interaction that contributes to axon growth suppression in vitro and regenerative failure in vivo These studies suggest potential therapeutic approaches to promote axon regeneration in injury and other degenerative diseases in the adult CNS.

Dysregulated miR-27a-3p promotes nasopharyngeal carcinoma cell proliferation and migration by targeting Mapk10.

miRNA-27a-3p is an important regulator of carcinogenesis and other pathological processes. However, its role in laryngeal carcinoma is still unknown. In our previous research, we found that miR-27a-3p expression was upregulated in nasopharyngeal carcinoma (NPC) using a microarray chip. In the present study, we identified miR-27a-3p as an endogenous promoter of metastatic invasion. The expression levels of miR-27a-3p were correlated with human metastatic progression outcomes and Kaplan-Meier survival. In silico database analyses revealed that Mapk10 is a potential target of miR-27a-3p, and luciferase reporter assay results revealed that miR-27a-3p directly inhibits the Mapk10 3' untranslated region (3'UTR). Real-time PCR and western blotting results ascertained that Mapk10 expression was regulated by miR­27a-3p. In addition, miR­27a-3p gain-of-function promoted cell proliferation, migration and invasion in 5-8 F NPC cells. These effects partially depended on Mapk10, and loss of miR­27a-3p function had the opposite effects.

Identification of the mechanisms by which age alters the mechanosensitivity of mesenchymal stromal cells on substrates of differing stiffness: Implications for osteogenesis and angiogenesis.

In order to identify the mechanisms by which skeletal maturity alters the mechanosensitivity of mesenchymal stromal cells (MSCs) and, the implications for osteogenesis and angiogenesis during bone formation, we compared the response of MSCs derived from children and skeletally-mature healthy adults cultured on soft and stiff collagen-coated polyacrylamide substrates. MSCs from children were more mechanosensitive, showing enhanced angiogenesis and osteogenesis on stiff substrates as indicated by increased endothelial tubule formation, PGF production, nuclear-translocation of YAP, ALP activity and mineralisation. To examine these mechanisms in more detail, a customised PCR array identified an age-dependent, stiffness-induced upregulation of NOX1, VEGFR1, VEGFR2, WIF1 and, of particular interest, JNK3 in cells from children compared to adults. When JNK3 activity was inhibited, a reduction in stiffness-induced driven osteogenesis was observed - suggesting that JNK3 might serve as a novel target for recapitulating the enhanced regenerative potential of children in adults suffering from bone degeneration. STATEMENT OF SIGNIFICANCE: We investigated the age-associated changes in the capacity of MSCs for bone regeneration involving the mechanosensitive signalling pathways, which reduce the ability of adult cells to respond to biophysical cues in comparison to cells from children, who are still undergoing bone development. Our results offer new insights into the mechanobiology of MSCs and sheds new light on age-altered mechanosensitivity and, on why children have such an immense capacity to regenerate their skeletal system. We have identified the mechanisms by which skeletal maturity alters the mechanosensitivity of mesenchymal stromal cells and an age-dependent, stiffness-induced upregulation of a number of prominent genes including, most notably, JNK3 in children cells, thus suggesting its potential to promote enhanced bone repair.

Cadmium impairs the survival and proliferation of cultured adult subventricular neural stem cells through activation of the JNK and p38 MAP kinases.

Cadmium (Cd) is a heavy metal with a long biological half-life in humans and is recognized as a toxic pollutant. Cd is also a potential neurotoxicant and its exposure is associated with olfactory impairment in humans. However, the molecular and cellular mechanisms of Cd neurotoxicity are not well defined. Adult neurogenesis is a process that generates functional neurons from adult neural stem/progenitor cells (aNPCs). It occurs in specific regions of the adult brain including the subventricular zone (SVZ) along the lateral ventricles in mammals, a process that is critical for olfaction. Various external stimuli can modulate adult neurogenesis and the effect of neurotoxicants on adult neurogenesis is just beginning to be elucidated. Since Cd exposure can impair olfaction in humans, the goal of this study is to investigate the effects of Cd on SVZ adult neurogenesis and underlying mechanisms using primary cultured SVZ-aNPCs. In this study, we report that low-level Cd exposure decreases cell number, induces apoptosis, and inhibits cell proliferation in SVZ-aNPCs. Furthermore, Cd exposure significantly increases phosphorylation of c-Jun NH2-terminal kinase (JNK), and p38 MAP kinase in these cells, indicative of JNK and p38 activation. Pharmacological inhibition of JNK or p38 MAPK kinases attenuated Cd-induced cell loss and apoptosis. Cd treatment did not cause cell loss or apoptosis in SVZ-aNPCs prepared from transgenic mice null for the neural-specific JNK3 isoform. These data suggest a critical role for p38 and JNK3 MAP kinases in Cd neurotoxicity. These results are, to our knowledge, the first demonstration that Cd impairs SVZ adult neurogenesis in vitro, which may contribute to its neurotoxicity in olfaction.