Protein kinase C (PKC) participates in acetaminophen hepatotoxicity through c-jun-N-terminal kinase (JNK)-dependent and -independent signaling pathways.

Unlabelled: This study examines the role of protein kinase C (PKC) and AMP-activated kinase (AMPK) in acetaminophen (APAP) hepatotoxicity. Treatment of primary mouse hepatocytes with broad-spectrum PKC inhibitors (Ro-31-8245, Go6983), protected against APAP cytotoxicity despite sustained c-jun-N-terminal kinase (JNK) activation. Broad-spectrum PKC inhibitor treatment enhanced p-AMPK levels and AMPK regulated survival-energy pathways including autophagy.

Hepatic vascular endothelial growth factor regulates recruitment of rat liver sinusoidal endothelial cell progenitor cells.

Background & Aims: After liver injury, bone marrow-derived liver sinusoidal endothelial cell progenitor cells (BM SPCs) repopulate the sinusoid as liver sinusoidal endothelial cells (LSECs). After partial hepatectomy, BM SPCs provide hepatocyte growth factor, promote hepatocyte proliferation, and are necessary for normal liver regeneration. We examined how hepatic vascular endothelial growth factor (VEGF) regulates recruitment of BM SPCs and their effects on liver injury.

Unique O-methoxyethyl ribose-DNA chimeric oligonucleotide induces an atypical melanoma differentiation-associated gene 5-dependent induction of type I interferon response.

Antisense oligonucleotides (ASO) containing 2'-O-methoxyethyl ribose (2'-MOE) modifications have been shown to possess both excellent pharmacokinetic properties and robust pharmacological activity in several animal models of human disease. 2'-MOE ASOs are generally well tolerated, displaying minimal to mild proinflammatory effect at doses far exceeding therapeutic doses. Although the vast majority of 2'-MOE ASOs are safe and well tolerated, a small subset of ASOs inducing acute inflammation in mice has been identified.

Role of differentiation of liver sinusoidal endothelial cells in progression and regression of hepatic fibrosis in rats.

Background & Aims: Capillarization, characterized by loss of differentiation of liver sinusoidal endothelial cells (LSECs), precedes the onset of hepatic fibrosis. We investigated whether restoration of LSEC differentiation would normalize crosstalk with activated hepatic stellate cells (HSC) and thereby promote quiescence of HSC and regression of fibrosis.

Methods: Rat LSECs were cultured with inhibitors and/or agonists and examined by scanning electron microscopy for fenestrae in sieve plates.

Silencing glycogen synthase kinase-3beta inhibits acetaminophen hepatotoxicity and attenuates JNK activation and loss of glutamate cysteine ligase and myeloid cell leukemia sequence 1.

Previously we demonstrated that c-Jun N-terminal kinase (JNK) plays a central role in acetaminophen (APAP)-induced liver injury. In the current work, we examined other possible signaling pathways that may also contribute to APAP hepatotoxicity. APAP treatment to mice caused glycogen synthase kinase-3beta (GSK-3beta) activation and translocation to mitochondria during the initial phase of APAP-induced liver injury ( approximately 1 h).

Differential effects of JNK1 and JNK2 inhibition on murine steatohepatitis and insulin resistance.

Unlabelled: Activation of c-Jun N-terminal kinase (JNK) has been implicated as a mechanism in the development of steatohepatitis. This finding, together with the reported role of JNK signaling in the development of obesity and insulin resistance, two components of the metabolic syndrome and predisposing factors for fatty liver disease, suggests that JNK may be a central mediator of the metabolic syndrome and an important therapeutic target in steatohepatitis. To define the isoform-specific functions of JNK in steatohepatitis associated with obesity and insulin resistance, the effects of JNK1 or JNK2 ablation were determined in developing and established steatohepatitis induced by a high-fat diet (HFD).

Regulation of H(2)O(2)-induced necrosis by PKC and AMP-activated kinase signaling in primary cultured hepatocytes.

Recent studies have suggested that, in certain cases, necrosis, like apoptosis, may be programmed, involving the activation and inhibition of many signaling pathways. In this study, we examined whether necrosis induced by H(2)O(2) is regulated by signaling pathways in primary hepatocytes. A detailed time course revealed that H(2)O(2) treated to hepatocytes is consumed within minutes, but hepatocytes undergo necrosis several hours later.

Role of JNK translocation to mitochondria leading to inhibition of mitochondria bioenergetics in acetaminophen-induced liver injury.

Previously, we demonstrated JNK plays a central role in acetaminophen (APAP)-induced liver injury (Gunawan, B. K., Liu, Z.

Anti-inflammatory activity of inhaled IL-4 receptor-alpha antisense oligonucleotide in mice.

The Th2 cytokines IL-4 and IL-13 mediate allergic pulmonary inflammation and airways hyperreactivity (AHR) in asthma models through signaling dependent upon the IL-4 receptor-alpha chain (IL-4Ralpha). IL-13 has been further implicated in the overproduction of mucus by the airway epithelium and in lung remodeling that commonly accompanies chronic inflammation. IL-4Ralpha-deficient mice are resistant to allergen-induced asthma, highlighting the therapeutic promise of selective molecular inhibitors of IL-4Ralpha.

c-Jun N-terminal kinase plays a major role in murine acetaminophen hepatotoxicity.

Background & Aims: In searching for effects of acetaminophen (APAP) on hepatocytes downstream of its metabolism that may participate in hepatotoxicity, we examined the role of stress kinases.

Methods: Mouse hepatocytes and C57BL/6 mice were administered a toxic dose of APAP with or without SP600125, a chemical c-jun N-terminal kinase (JNK) inhibitor. JNK activity as reflected in phospho-c-jun levels, serum alanine transaminase (ALT), and liver histology were assessed.

Ezrin/radixin/moesin proteins are phosphorylated by TNF-alpha and modulate permeability increases in human pulmonary microvascular endothelial cells.

Endothelial cells (ECs) respond to TNF-alpha by altering their F-actin cytoskeleton and junctional permeability through mechanisms that include protein kinase C (PKC) and p38 MAPK. Ezrin, radixin, and moesin (ERM) regulate many cell processes that often require a conformational change of these proteins as a result of phosphorylation on a conserved threonine residue near the C terminus. This study tested the hypothesis that ERM proteins are phosphorylated on this critical threonine residue through TNF-alpha-induced activation of PKC and p38 and modulate permeability increases in pulmonary microvascular ECs.

MKK3 and -6-dependent activation of p38alpha MAP kinase is required for cytoskeletal changes in pulmonary microvascular endothelial cells induced by ICAM-1 ligation.

Previous studies demonstrated that neutrophil adherence induces ICAM-1-dependent cytoskeletal changes in TNF-alpha-treated pulmonary microvascular endothelial cells that are prevented by a pharmacological inhibitor of p38 MAP kinase. This study determined whether neutrophil adherence induces activation of p38 MAP kinase in endothelial cells, the subcellular localization of phosphorylated p38, which MAP kinase kinases lead to p38 activation, which p38 isoform is activated, and what the downstream targets may be. Confocal microscopy showed that neutrophil adhesion for 2 or 6 min induced an increase in phosphorylated p38 in endothelial cells that was punctate and concentrated in the central region of the endothelial cells.

Reduction in glucagon receptor expression by an antisense oligonucleotide ameliorates diabetic syndrome in db/db mice.

Excess glucagon levels contribute to the hyperglycemia associated with type 2 diabetes. Reducing glucagon receptor expression may thus ameliorate the consequences of hyperglucagonemia and improve blood glucose control in diabetic patients. This study describes the antidiabetic effects of a specific glucagon receptor antisense oligonucleotide (GR-ASO) in db/db mice.

Inhibition of cell proliferation and cell cycle progression by specific inhibition of basal JNK activity: evidence that mitotic Bcl-2 phosphorylation is JNK-independent.

The c-Jun NH(2)-terminal kinase (JNK) subgroup of mitogen-activated protein kinases has been implicated largely in stress responses, but an increasing body of evidence has suggested that JNK also plays a role in cell proliferation and survival. We examined the effect of JNK inhibition, using either SP600125 or specific antisense oligonucleotides, on cell proliferation and cell cycle progression. SP600125 was selective for JNK in vitro and in vivo versus other kinases tested including ERK, p38, cyclin-dependent protein kinase 1 (CDK1), and CDK2.

Activation of SRC tyrosine kinases in response to ICAM-1 ligation in pulmonary microvascular endothelial cells.

Previous studies demonstrated that ICAM-1 ligation on human pulmonary microvascular endothelial cells (ECs) sequentially induces activation of xanthine oxidase and p38 MAPK. Inhibition of these signaling events reduces neutrophil migration to the EC borders. This study examined the role of SRC tyrosine kinases in ICAM-1-initiated signaling within these ECs.

Shear-induced cyclooxygenase-2 via a JNK2/c-Jun-dependent pathway regulates prostaglandin receptor expression in chondrocytic cells.

Using cDNA microarrays coupled with bioinformatics tools, we elucidated a signaling cascade regulating cyclooxygenase-2 (COX-2), a pivotal pro-inflammatory enzyme expressed in rheumatic and osteoarthritic, but not normal, cartilage. Exposure of T/C-28a2 chondrocytic cells to fluid shear results in co-regulation of c-Jun N-terminal kinase2 (JNK2), c-Jun, and COX-2 as well as concomitant downstream expression of prostaglandin receptors EP2 and EP3a1. JNK2 transcript inhibition abrogated shear-induced COX-2, EP2, and EP3a1 mRNA up-regulation as well as c-Jun phosphorylation.

Targets of c-Jun NH(2)-terminal kinase 2-mediated tumor growth regulation revealed by serial analysis of gene expression.

Although the c-Jun NH(2)-terminal kinase (JNK) pathway has been implicated in mediating cell growth and transformation, its downstream effectors remain to be identified. Using JNK2 antisense oligonucleotides (JNK2AS), we uncovered previously a role for JNK2 in regulating cell cycle progression and survival of human PC3 prostate carcinoma cells. Here, to identify genes involved in implementing JNK2-mediated effects, we have analyzed global gene expression changes in JNK2-deprived PC3 cells using Serial Analysis of Gene Expression.

Specific inhibition of PTEN expression reverses hyperglycemia in diabetic mice.

Signaling through the phosphatidylinositol 3'-kinase (PI3K) pathway is crucial for metabolic responses to insulin, and defects in PI3K signaling have been demonstrated in type 2 diabetes. PTEN (MMAC1) is a lipid/protein phosphatase that can negatively regulate the PI3K pathway by dephosphorylating phosphatidylinositol (3,4,5)-triphosphate, but it is unclear whether PTEN is physiologically relevant to insulin signaling in vivo. We employed an antisense oligonucleotide (ASO) strategy in an effort to specifically inhibit the expression of PTEN.