Phosphorylation of RXRα mediates the effect of JNK to suppress hepatic FGF21 expression and promote metabolic syndrome.

The cJun NH-terminal kinase (JNK) signaling pathway in the liver promotes systemic changes in metabolism by regulating peroxisome proliferator-activated receptor α (PPARα)-dependent expression of the hepatokine fibroblast growth factor 21 (FGF21). Hepatocyte-specific gene ablation studies demonstrated that the gene (encoding JNK2) plays a key mechanistic role. Mutually exclusive inclusion of exons 7a and 7b yields expression of the isoforms JNK2α and JNK2β.

Neutrophil infiltration regulates clock-gene expression to organize daily hepatic metabolism.

Liver metabolism follows diurnal fluctuations through the modulation of molecular clock genes. Disruption of this molecular clock can result in metabolic disease but its potential regulation by immune cells remains unexplored. Here, we demonstrated that in steady state, neutrophils infiltrated the mouse liver following a circadian pattern and regulated hepatocyte clock-genes by neutrophil elastase (NE) secretion.

High-fat diet in a mouse insulin-resistant model induces widespread rewiring of the phosphotyrosine signaling network.

Obesity-associated type 2 diabetes and accompanying diseases have developed into a leading human health risk across industrialized and developing countries. The complex molecular underpinnings of how lipid overload and lipid metabolites lead to the deregulation of metabolic processes are incompletely understood. We assessed hepatic post-translational alterations in response to treatment of cells with saturated and unsaturated free fatty acids and the consumption of a high-fat diet by mice.

Cutting Edge: Early Attrition of Memory T Cells during Inflammation and Costimulation Blockade Is Regulated Concurrently by Proapoptotic Proteins Fas and Bim.

Apoptosis of CD8 T cells is an essential mechanism that maintains immune system homeostasis, prevents autoimmunity, and reduces immunopathology. CD8 T cell death also occurs early during the response to both inflammation and costimulation blockade (CoB). In this article, we studied the effects of a combined deficiency of Fas (extrinsic pathway) and Bim (intrinsic pathway) on early T cell attrition in response to lymphocytic choriomeningitis virus infection and during CoB during transplantation.

JIP1-Mediated JNK Activation Negatively Regulates Synaptic Plasticity and Spatial Memory.

The c-Jun N-terminal kinase (JNK) signal transduction pathway is implicated in learning and memory. Here, we examined the role of JNK activation mediated by the JNK-interacting protein 1 (JIP1) scaffold protein. We compared male wild-type mice with a mouse model harboring a point mutation in the gene that selectively blocks JIP1-mediated JNK activation.

Hepatic Dysfunction Caused by Consumption of a High-Fat Diet.

Obesity is a major human health crisis that promotes insulin resistance and, ultimately, type 2 diabetes. The molecular mechanisms that mediate this response occur across many highly complex biological regulatory levels that are incompletely understood. Here, we present a comprehensive molecular systems biology study of hepatic responses to high-fat feeding in mice.

Hyper- and hypo- nutrition studies of the hepatic transcriptome and epigenome suggest that PPARα regulates anaerobic glycolysis.

Diet plays a crucial role in shaping human health and disease. Diets promoting obesity and insulin resistance can lead to severe metabolic diseases, while calorie-restricted (CR) diets can improve health and extend lifespan. In this work, we fed mice either a chow diet (CD), a 16 week high-fat diet (HFD), or a CR diet to compare and contrast the effects of these diets on mouse liver biology.

Excitatory transmission onto AgRP neurons is regulated by cJun NH2-terminal kinase 3 in response to metabolic stress.

The cJun NH2-terminal kinase (JNK) signaling pathway is implicated in the response to metabolic stress. Indeed, it is established that the ubiquitously expressed JNK1 and JNK2 isoforms regulate energy expenditure and insulin resistance. However, the role of the neuron-specific isoform JNK3 is unclear.

Novel Observations From Next-Generation RNA Sequencing of Highly Purified Human Adult and Fetal Islet Cell Subsets.

Understanding distinct gene expression patterns of normal adult and developing fetal human pancreatic α- and β-cells is crucial for developing stem cell therapies, islet regeneration strategies, and therapies designed to increase β-cell function in patients with diabetes (type 1 or 2). Toward that end, we have developed methods to highly purify α-, β-, and δ-cells from human fetal and adult pancreata by intracellular staining for the cell-specific hormone content, sorting the subpopulations by flow cytometry, and, using next-generation RNA sequencing, we report the detailed transcriptomes of fetal and adult α- and β-cells. We observed that human islet composition was not influenced by age, sex, or BMI, and transcripts for inflammatory gene products were noted in fetal β-cells.

Regulation of Adipose Tissue Inflammation and Insulin Resistance by MAPK Phosphatase 5.

Obesity and metabolic disorders such as insulin resistance and type 2 diabetes have become a major threat to public health globally. The mechanisms that lead to insulin resistance in type 2 diabetes have not been well understood. In this study, we show that mice deficient in MAPK phosphatase 5 (MKP5) develop insulin resistance spontaneously at an early stage of life and glucose intolerance at a later age.

Analysis of in vitro insulin-resistance models and their physiological relevance to in vivo diet-induced adipose insulin resistance.

Diet-induced obesity (DIO) predisposes individuals to insulin resistance, and adipose tissue has a major role in the disease. Insulin resistance can be induced in cultured adipocytes by a variety of treatments, but what aspects of the in vivo responses are captured by these models remains unknown. We use global RNA sequencing to investigate changes induced by TNF-α, hypoxia, dexamethasone, high insulin, and a combination of TNF-α and hypoxia, comparing the results to the changes in white adipose tissue from DIO mice.

Myocardial ischaemia is associated with an elevated brain natriuretic pepide level even in the presence of left ventricular systolic dysfunction.

Aims: Plasma BNP and high-sensitivity cardiac troponin-T (hs-TnT) are elevated by both ischaemia and LV systolic dysfunction (LVSD). As a result, it is unknown whether BNP and/or hs-TnT could be useful biomarkers to identify ischaemia in the presence of LVSD.

Methods And Results: Three separate patient populations were studied.

Requirement of c-Jun NH(2)-terminal kinase for Ras-initiated tumor formation.

The c-Jun NH(2)-terminal kinase (JNK) signal transduction pathway causes increased gene expression mediated, in part, by members of the activating transcription factor protein (AP1) group. JNK is therefore implicated in the regulation of cell growth and cancer. To test the role of JNK in Ras-induced tumor formation, we examined the effect of compound ablation of the ubiquitously expressed genes Jnk1 plus Jnk2.

Role of muscle c-Jun NH2-terminal kinase 1 in obesity-induced insulin resistance.

Obesity caused by feeding of a high-fat diet (HFD) is associated with an increased activation of c-Jun NH(2)-terminal kinase 1 (JNK1). Activated JNK1 is implicated in the mechanism of obesity-induced insulin resistance and the development of metabolic syndrome and type 2 diabetes. Significantly, Jnk1(-)(/)(-) mice are protected against HFD-induced obesity and insulin resistance.

Signal transduction cross talk mediated by Jun N-terminal kinase-interacting protein and insulin receptor substrate scaffold protein complexes.

Scaffold proteins have been established as important mediators of signal transduction specificity. The insulin receptor substrate (IRS) proteins represent a critical group of scaffold proteins that are required for signal transduction by the insulin receptor, including the activation of phosphatidylinositol 3 kinase. The c-Jun NH(2)-terminal kinase (JNK)-interacting proteins (JIPs) represent a different group of scaffold molecules that are implicated in the regulation of the JNK.

Requirement of JIP scaffold proteins for NMDA-mediated signal transduction.

JIP scaffold proteins are implicated in the regulation of protein kinase signal transduction pathways. To test the physiological role of these scaffold proteins, we examined the phenotype of compound mutant mice that lack expression of JIP proteins. These mice were found to exhibit severe defects in N-methyl-D-aspartic acid (NMDA) receptor function, including decreased NMDA-evoked current amplitude, cytoplasmic Ca(++), and gene expression.

Identification of the JNK signaling pathway as a functional target of the tumor suppressor PTEN.

Although most oncogenic phenotypes of PTEN loss are attributed to AKT activation, AKT alone is not sufficient to induce all of the biological activities associated with PTEN inactivation. We searched for additional PTEN-regulated pathways through gene set enrichment analysis (GSEA) and identified genes associated with JNK activation. PTEN null cells exhibit higher JNK activity, and genetic studies demonstrate that JNK functions parallel to and independently of AKT.

A radical role for p38 MAPK in tumor initiation.

It is established that p38 MAPK can negatively regulate tumorigenesis, but the mechanism is incompletely understood. A new study in this issue of Cancer Cell shows that p38 MAP kinase plays a selective role in tumor initiation mediated by oxidative stress.

Control of cellular senescence by CPEB.

Cytoplasmic polyadenylation element-binding protein (CPEB) is a sequence-specific RNA-binding protein that promotes polyadenylation-induced translation. While a CPEB knockout (KO) mouse is sterile but overtly normal, embryo fibroblasts derived from this mouse (MEFs) do not enter senescence in culture as do wild-type MEFs, but instead are immortal. Exogenous CPEB restores senescence in the KO MEFs and also induces precocious senescence in wild-type MEFs.

Elevated levels of natriuretic peptides in patients with pulmonary thromboembolism.

Background: Pulmonary thromboembolism (PTE) occurs in a wide variety of clinical settings and presents a diagnostic challenge to clinicians, often requiring extensive imaging of the vascular bed. Management increasingly requires accurate risk stratification to rapidly identify those with massive and submassive PTE requiring different therapeutic strategies such as thrombolysis. Provision of a rapid blood test that improves diagnostic certainty and helps stratify risk could therefore bridge the gap between uncertainty and delivery of immediate early life-saving treatment.

Regulation of innate and adaptive immune responses by MAP kinase phosphatase 5.

Mitogen-activated protein (MAP) kinases are essential regulators in immune responses, and their activities are modulated by kinases and phosphatases. MAP kinase phosphatase (MKP) is a family of dual-specificity phosphatases whose function is evolutionarily conserved. A number of mammalian MKPs have been identified so far, but their specific physiological functions in negative regulation of MAP kinases have not been genetically defined.

JNK regulates autocrine expression of TGF-beta1.

The c-Jun NH2-terminal kinase (JNK) has been implicated in the function of transforming growth factor beta (TGF-beta). To test the role of JNK, we examined the effect of compound disruption of the murine genes that encode the ubiquitously expressed isoforms of JNK (Jnk1 and Jnk2). We report that JNK-deficient fibroblasts isolated from Jnk1-/- Jnk2-/- mice constitutively express TGF-beta1.

Role of JNK in tumor development.

The c-Jun NH2-terminal kinase (JNK) is implicated in oncogenic transformation. However, studies of the effect of Jnk gene disruption on Ras-induced transformation of murine fibroblasts indicate that JNK may act as a suppressor of Ras transformation and that the JNK signaling pathway contributes to the apoptotic elimination of transformed cells in vivo. The conclusion that JNK can act as a tumor suppressor is consistent with the presence of loss-of-function mutations in JNK pathway components (Jnk3 and Mkk4) in human tumors.

c-Jun NH(2)-terminal kinase is essential for the regulation of AP-1 by tumor necrosis factor.

The c-Jun NH(2)-terminal kinase (JNK) is activated by the cytokine tumor necrosis factor (TNF). This pathway is implicated in the regulation of AP-1-dependent gene expression by TNF. To examine the role of the JNK signaling pathway, we compared the effects of TNF on wild-type and Jnk1(-/-) Jnk2(-/-) murine embryo fibroblasts.