Unveiling the Role of Oxidative Stress in Cochlear Hair Cell Death: Prospective Phytochemical Therapeutics against Sensorineural Hearing Loss.

Hearing loss represents a multifaceted and pervasive challenge that deeply impacts various aspects of an individual's life, spanning psychological, emotional, social, and economic realms. Understanding the molecular underpinnings that orchestrate hearing loss remains paramount in the quest for effective therapeutic strategies. This review aims to expound upon the physiological, biochemical, and molecular aspects of hearing loss, with a specific focus on its correlation with diabetes. Within this context, phytochemicals have surfaced as prospective contenders in the pursuit of potential adjuvant therapies. These compounds exhibit noteworthy antioxidant and anti-inflammatory properties, which hold the potential to counteract the detrimental effects induced by oxidative stress and inflammation-prominent contributors to hearing impairment. Furthermore, this review offers an up-to-date exploration of the diverse molecular pathways modulated by these compounds. However, the dynamic landscape of their efficacy warrants recognition as an ongoing investigative topic, inherently contingent upon specific experimental models. Ultimately, to ascertain the genuine potential of phytochemicals as agents in hearing loss treatment, a comprehensive grasp of the molecular mechanisms at play, coupled with rigorous clinical investigations, stands as an imperative quest.

Ginsenoside Rc from Panax Ginseng Ameliorates Palmitate-Induced UB/OC-2 Cochlear Cell Injury.

By 2050, at least 700 million people will require hearing therapy while 2.5 billion are projected to suffer from hearing loss. Sensorineural hearing loss (SNHL) arises from the inability of the inner ear to convert fluid waves into neural electric signals because of injury to cochlear hair cells that has resulted in their death. In addition, systemic chronic inflammation implicated in other pathologies may exacerbate cell death leading to SNHL. Phytochemicals have emerged as a possible solution because of the growing evidence of their anti-inflammatory, antioxidant, and anti-apoptotic properties. Ginseng and its bioactive molecules, ginsenosides, exhibit effects that suppress pro-inflammatory signaling and protect against apoptosis. In the current study, we investigated the effects of ginsenoside Rc (G-Rc) on UB/OC-2 primary murine sensory hair cell survival in response to palmitate-induced injury. G-Rc promoted UB/OC-2 cell survival and cell cycle progression. Additionally, G-Rc enhanced the differentiation of UB/OC-2 cells into functional sensory hair cells and alleviated palmitate-induced inflammation, endoplasmic reticulum stress, and apoptosis. The current study offers novel insights into the effects of G-Rc as a potential adjuvant for SNHL and warrants further studies elucidating the molecular mechanisms.

Podocyte specific deletion of PKM2 ameliorates LPS-induced podocyte injury through beta-catenin.

BACKGROUND: Acute kidney injury (AKI) is associated with a severe decline in kidney function caused by abnormalities within the podocytes' glomerular matrix. Recently, AKI has been linked to alterations in glycolysis and the activity of glycolytic enzymes, including pyruvate kinase M2 (PKM2). However, the contribution of this enzyme to AKI remains largely unexplored. METHODS: Cre-loxP technology was used to examine the effects of PKM2 specific deletion in podocytes on the activation status of key signaling pathways involved in the pathophysiology of AKI by lipopolysaccharides (LPS). In addition, we used lentiviral shRNA to generate murine podocytes deficient in PKM2 and investigated the molecular mechanisms mediating PKM2 actions in vitro. RESULTS: Specific PKM2 deletion in podocytes ameliorated LPS-induced protein excretion and alleviated LPS-induced alterations in blood urea nitrogen and serum albumin levels. In addition, PKM2 deletion in podocytes alleviated LPS-induced structural and morphological alterations to the tubules and to the brush borders. At the molecular level, PKM2 deficiency in podocytes suppressed LPS-induced inflammation and apoptosis. In vitro, PKM2 knockdown in murine podocytes diminished LPS-induced apoptosis. These effects were concomitant with a reduction in LPS-induced activation of ß-catenin and the loss of Wilms' Tumor 1 (WT1) and nephrin. Notably, the overexpression of a constitutively active mutant of ß-catenin abolished the protective effect of PKM2 knockdown. Conversely, PKM2 knockdown cells reconstituted with the phosphotyrosine binding-deficient PKM2 mutant (K433E) recapitulated the effect of PKM2 depletion on LPS-induced apoptosis, ß-catenin activation, and reduction in WT1 expression. CONCLUSIONS: Taken together, our data demonstrates that PKM2 plays a key role in podocyte injury and suggests that targetting PKM2 in podocytes could serve as a promising therapeutic strategy for AKI. TRIAL REGISTRATION: Not applicable. Video abstract.

Role of zinc transporter ZIP12 in susceptibility-weighted brain magnetic resonance imaging (MRI) phenotypes and mitochondrial function.

Brain zinc dysregulation is linked to many neurological disorders. However, the mechanisms regulating brain zinc homeostasis are poorly understood. We performed secondary analyses of brain MRI GWAS and exome sequencing data from adults in the UK Biobank. Coding ZIP12 polymorphisms in zinc transporter ZIP12 (SLC39A12) were associated with altered brain susceptibility weighted MRI (swMRI). Conditional and joint association analyses revealed independent GWAS signals in linkage disequilibrium with 2 missense ZIP12 polymorphisms, rs10764176 and rs72778328, with reduced zinc transport activity. ZIP12 rare coding variants predicted to be deleterious were associated with similar impacts on brain swMRI. In Neuro-2a cells, ZIP12 deficiency by short hairpin RNA (shRNA) depletion or CRISPR/Cas9 genome editing resulted in impaired mitochondrial function, increased superoxide presence, and detectable protein carbonylation. Inhibition of Complexes I and IV of the electron transport chain reduced neurite outgrowth in ZIP12 deficient cells. Transcriptional coactivator PGC-1α, mitochondrial superoxide dismutase (SOD2), and chemical antioxidants α-tocopherol, MitoTEMPO, and MitoQ restored neurite extension impaired by ZIP12 deficiency. Mutant forms of α-synuclein and tau linked to familial Parkinson's disease and frontotemporal dementia, respectively, reduced neurite outgrowth in cells deficient in ZIP12. Zinc and ZIP12 may confer resilience against neurological diseases or premature aging of the brain.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs.

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Differential Effects of 17,18-EEQ and 19,20-EDP Combined with Soluble Epoxide Hydrolase Inhibitor t-TUCB on Diet-Induced Obesity in Mice.

17,18-Epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP) are bioactive epoxides produced from n-3 polyunsaturated fatty acid eicosapentaenoic acid and docosahexaenoic acid, respectively. However, these epoxides are quickly metabolized into less active diols by soluble epoxide hydrolase (sEH). We have previously demonstrated that an sEH inhibitor, t-TUCB, decreased serum triglycerides (TG) and increased lipid metabolic protein expression in the brown adipose tissue (BAT) of diet-induced obese mice. This study investigates the preventive effects of t-TUCB (T) alone or combined with 19,20-EDP (T + EDP) or 17,18-EEQ (T + EEQ) on BAT activation in the development of diet-induced obesity and metabolic disorders via osmotic minipump delivery in mice. Both T + EDP and T + EEQ groups showed significant improvement in fasting glucose, serum triglycerides, and higher core body temperature, whereas heat production was only significantly increased in the T + EEQ group. Moreover, both the T + EDP and T + EEQ groups showed less lipid accumulation in the BAT. Although UCP1 expression was not changed, PGC1α expression was increased in all three treated groups. In contrast, the expression of CPT1A and CPT1B, which are responsible for the rate-limiting step for fatty acid oxidation, was only increased in the T + EDP and T + EEQ groups. Interestingly, as a fatty acid transporter, CD36 expression was only increased in the T + EEQ group. Furthermore, both the T + EDP and T + EEQ groups showed decreased inflammatory NFκB signaling in the BAT. Our results suggest that 17,18-EEQ or 19,20-EDP combined with t-TUCB may prevent high-fat diet-induced metabolic disorders, in part through increased thermogenesis, upregulating lipid metabolic protein expression, and decreasing inflammation in the BAT.

Zyflamend induces apoptosis in pancreatic cancer cells via modulation of the JNK pathway.

BACKGROUND: Current pharmacological therapies and treatments targeting pancreatic neuroendocrine tumors (PNETs) have proven ineffective, far too often. Therefore, there is an urgent need for alternative therapeutic approaches. Zyflamend, a combination of anti-inflammatory herbal extracts, that has proven to be effective in various in vitro and in vivo cancer platforms, shows promise. However, its effects on pancreatic cancer, in particular, remain largely unexplored. METHODS: In the current study, we investigated the effects of Zyflamend on the survival of beta-TC-6 pancreatic insulinoma cells (ß-TC6) and conducted a detailed analysis of the underlying molecular mechanisms. RESULTS: Herein, we demonstrate that Zyflamend treatment decreased cell proliferation in a dose-dependent manner, concomitant with increased apoptotic cell death and cell cycle arrest at the G2/M phase. At the molecular level, treatment with Zyflamend led to the induction of ER stress, autophagy, and the activation of c-Jun N-terminal kinase (JNK) pathway. Notably, pharmacological inhibition of JNK abrogated the pro-apoptotic effects of Zyflamend. Furthermore, Zyflamend exacerbated the effects of streptozotocin and adriamycin-induced ER stress, autophagy, and apoptosis. CONCLUSION: The current study identifies Zyflamend as a potential novel adjuvant in the treatment of pancreatic cancer via modulation of the JNK pathway. Video abstract.

Soluble Epoxide Hydrolase Inhibition by t-TUCB Promotes Brown Adipogenesis and Reduces Serum Triglycerides in Diet-Induced Obesity.

Brown adipose tissue (BAT) is an important target for obesity treatment and prevention. Soluble epoxide hydrolase (sEH) converts bioactive epoxy fatty acids (EpFAs) into less active diols. sEH inhibitors (sEHI) are beneficial in many chronic diseases by stabilizing EpFAs. However, roles of sEH and sEHI in brown adipogenesis and BAT activity in treating diet-induced obesity (DIO) have not been reported. sEH expression was studied in in vitro models of brown adipogenesis and the fat tissues of DIO mice. The effects of the sEHI, trans-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy-benzoic acid (t-TUCB), were studied in vitro and in the obese mice via mini osmotic pump delivery. sEH expression was increased in brown adipogenesis and the BAT of the DIO mice. t-TUCB promoted brown adipogenesis in vitro. Although t-TCUB did not change body weight, fat pad weight, or glucose and insulin tolerance in the obese mice, it decreased serum triglycerides and increased protein expression of genes important for lipid metabolism in the BAT. Our results suggest that sEH may play a critical role in brown adipogenesis, and sEHI may be beneficial in improving BAT protein expression involved in lipid metabolism. Further studies using the sEHI combined with EpFA generating diets for obesity treatment and prevention are warranted.

Idebenone is a cytoprotective insulin sensitizer whose mechanism is Shc inhibition.

When insulin binds insulin receptor, IRS1 signaling is stimulated to trigger the maximal insulin response. p52Shc protein competes directly with IRS1, thus damping and diverting maximal insulin response. Genetic reduction of p52Shc minimizes competition with IRS1, and improves insulin signaling and glucose control in mice, and improves pathophysiological consequences of hyperglycemia. Given the multiple benefits of Shc reduction in vivo, we investigated whether any of 1680 drugs used in humans may function as Shc inhibitors, and thus potentially serve as novel anti-diabetics. Of the 1680, 30 insulin sensitizers were identified by screening in vitro, and of these 30 we demonstrated that 7 bound Shc protein. Of the 7 drugs, idebenone dose-dependently bound Shc protein in the 50-100 nM range, and induced insulin sensitivity and cytoprotection in this same 100 nM range that clinically dosed idebenone reaches in human plasma. By contrast we observe mitochondrial effects of idebenone in the 5,000 nM range that are not reached in human dosing. Multiple assays of target engagement demonstrate that idebenone physically interacts with Shc protein. Idebenone sensitizes mice to insulin in two different mouse models of prediabetes. Genetic depletion of idebenone's target eliminates idebenone's ability to insulin-sensitize in vivo. Thus, idebenone is the first-in-class member of a novel category of insulin-sensitizing and cytoprotective agents, the Shc inhibitors. Idebenone is an approved drug and could be considered for other indications such as type 2 diabetes and fatty liver disease, in which insulin resistance occurs.

Endoplasmic reticulum stress in the peripheral nervous system is a significant driver of neuropathic pain.

Despite intensive effort and resulting gains in understanding the mechanisms underlying neuropathic pain, limited success in therapeutic approaches have been attained. A recently identified, nonchannel, nonneurotransmitter therapeutic target for pain is the enzyme soluble epoxide hydrolase (sEH). The sEH degrades natural analgesic lipid mediators, epoxy fatty acids (EpFAs), therefore its inhibition stabilizes these bioactive mediators. Here we demonstrate the effects of EpFAs on diabetes induced neuropathic pain and define a previously unknown mechanism of pain, regulated by endoplasmic reticulum (ER) stress. The activation of ER stress is first quantified in the peripheral nervous system of type I diabetic rats. We demonstrate that both pain and markers of ER stress are reversed by a chemical chaperone. Next, we identify the EpFAs as upstream modulators of ER stress pathways. Chemical inducers of ER stress invariably lead to pain behavior that is reversed by a chemical chaperone and an inhibitor of sEH. The rapid occurrence of pain behavior with inducers, equally rapid reversal by blockers and natural incidence of ER stress in diabetic peripheral nervous system (PNS) argue for a major role of the ER stress pathways in regulating the excitability of the nociceptive system. Understanding the role of ER stress in generation and maintenance of pain opens routes to exploit this system for therapeutic purposes.

Concurrent regulation of LKB1 and CaMKK2 in the activation of AMPK in castrate-resistant prostate cancer by a well-defined polyherbal mixture with anticancer properties.

BACKGROUND: Zyflamend, a blend of herbal extracts, effectively inhibits tumor growth using preclinical models of castrate-resistant prostate cancer mediated in part by 5'-adenosine monophosphate-activated protein kinase (AMPK), a master energy sensor of the cell. Clinically, treatment with Zyflamend and/or metformin (activators of AMPK) had benefits in castrate-resistant prostate cancer patients who no longer responded to treatment. Two predominant upstream kinases are known to activate AMPK: liver kinase B1 (LKB1), a tumor suppressor, and calcium-calmodulin kinase kinase-2 (CaMKK2), a tumor promotor over-expressed in many cancers. The objective was to interrogate how Zyflamend activates AMPK by determining the roles of LKB1 and CaMKK2. METHODS: AMPK activation was determined in CWR22Rv1 cells treated with a variety of inhibitors of LKB1 and CaMKK2 in the presence and absence of Zyflamend, and in LKB1-null HeLa cells that constitutively express CaMKK2, following transfection with wild type LKB1 or catalytically-dead mutants. Upstream regulation by Zyflamend of LKB1 and CaMKK2 was investigated targeting protein kinase C-zeta (PKCζ) and death-associated protein kinase (DAPK), respectively. RESULTS: Zyflamend's activation of AMPK appears to be LKB1 dependent, while simultaneously inhibiting CaMKK2 activity. Zyflamend failed to rescue the activation of AMPK in the presence of pharmacological and molecular inhibitors of LKB1, an effect not observed in the presence of inhibitors of CaMKK2. Using LKB1-null and catalytically-dead LKB1-transfected HeLa cells that constitutively express CaMKK2, ionomycin (activator of CaMKK2) increased phosphorylation of AMPK, but Zyflamend only had an effect in cells transfected with wild type LKB1. Zyflamend appears to inhibit CaMKK2 by DAPK-mediated phosphorylation of CaMKK2 at Ser511, an effect prevented by a DAPK inhibitor. Alternatively, Zyflamend mediates LKB1 activation via increased phosphorylation of PKCζ, where it induced translocation of PKCζ and LKB1 to their respective active compartments in HeLa cells following treatment. Altering the catalytic activity of LKB1 did not alter this translocation. DISCUSSION: Zyflamend's activation of AMPK is mediated by LKB1, possibly via PKCζ, but independent of CaMKK2 by a mechanism that appears to involve DAPK. CONCLUSIONS: Therefore, this is the first evidence that natural products simultaneously and antithetically regulate upstream kinases, known to be involved in cancer, via the activation of AMPK.

TGR5 contributes to glucoregulatory improvements after vertical sleeve gastrectomy in mice.

OBJECTIVE: Vertical sleeve gastrectomy (VSG) produces high rates of type 2 diabetes remission; however, the mechanisms responsible remain incompletely defined. VSG increases circulating bile acid concentrations and bile acid signalling through TGR5 improves glucose homeostasis. Therefore, we investigated the role of TGR5 signalling in mediating the glucoregulatory benefits of VSG. DESIGN: VSG or sham surgery was performed in high-fat-fed male Tgr5+/+ (wild type) and Tgr5-/- (knockout) littermates. Sham-operated mice were fed ad libitum or food restricted to match their body weight to VSG-operated mice. Body weight, food intake, energy expenditure, insulin signalling and circulating bile acid profiles were measured and oral glucose tolerance testing, islet immunohistochemistry and gut microbial profiling were performed. RESULTS: VSG decreased food intake and body weight, increased energy expenditure and circulating bile acid concentrations, improved fasting glycaemia, glucose tolerance and glucose-stimulated insulin secretion, enhanced nutrient-stimulated glucagon-like peptide 1 secretion and produced favourable shifts in gut microbial populations in both genotypes. However, the body weight-independent improvements in fasting glycaemia, glucose tolerance, hepatic insulin signalling, hepatic inflammation and islet morphology after VSG were attenuated in Tgr5-/- relative to Tgr5+/+ mice. Furthermore, VSG produced metabolically favourable alterations in circulating bile acid profiles that were blunted in Tgr5-/- relative to Tgr5+/+ mice. TGR5-dependent regulation of hepatic Cyp8b1 expression may have contributed to TGR5-mediated shifts in the circulating bile acid pool after VSG. CONCLUSIONS: These results suggest that TGR5 contributes to the glucoregulatory benefits of VSG surgery by promoting metabolically favourable shifts in the circulating bile acid pool.

p46Shc Inhibits Thiolase and Lipid Oxidation in Mitochondria.

Although the p46Shc isoform has been known to be mitochondrially localized for 11 years, its function in mitochondria has been a mystery. We confirmed p46Shc to be mitochondrially localized and showed that the major mitochondrial partner of p46Shc is the lipid oxidation enzyme 3-ketoacylCoA thiolase ACAA2, to which p46Shc binds directly and with a strong affinity. Increasing p46Shc expression inhibits, and decreasing p46Shc stimulates enzymatic activity of thiolase in vitro Thus, we suggest p46Shc to be a negative mitochondrial thiolase activity regulator, and reduction of p46Shc expression activates thiolase. This is the first demonstration of a protein that directly binds and controls thiolase activity. Thiolase was thought previously only to be regulated by metabolite balance and steady-state flux control. Thiolase is the last enzyme of the mitochondrial fatty acid beta-oxidation spiral, and thus is important for energy metabolism. Mice with reduction of p46Shc are lean, resist obesity, have higher lipid oxidation capacity, and increased thiolase activity. The thiolase-p46Shc connection shown here in vitro and in organello may be an important underlying mechanism explaining the metabolic phenotype of Shc-depleted mice in vivo.

Characterization of the Pro-Inflammatory Cytokine IL-1ß on Butyrate Oxidation in Colorectal Cancer Cells.

Cancer, in part, is driven, by alterations in cellular metabolism that promote cell survival and cell proliferation. Identifying factors that influence this shift in cellular metabolism in cancer cells is important. Interleukin-1ß (IL-1ß) is a pro-inflammatory cytokine that has been reported to be elevated in colorectal cancer patients. While much is known toward the effect of dietary nutrients on regulating inflammation and the inflammatory response, which includes cytokines such as IL-1ß, far less is understood how cytokines impact nutrient fate to alter cancer cell metabolism. Butyrate, a nutrient derived from the fermentation of dietary fiber in the colon, is the preferential exogenous energetic substrate used by non-cancerous colonocytes, but is used less efficiently by colorectal cancer cells. To test whether IL-1ß alters colonocyte energy metabolism, we measured butyrate oxidation in HCT116 colorectal cancer cells with and without IL-1ß. We hypothesize that IL-1ß will push cancerous colonocytes away from the utilization and oxidation of butyrate. In this study, we demonstrate that pretreatment of colorectal cancer cells with IL-1ß diminished butyrate oxidation and NADH levels. This effect was blocked with the interleukin receptor antagonist A (IL-1RA). Moreover, IL-1ß suppressed basal mitochondrial respiration and lowered the mitochondrial spare capacity. By using inhibitors to block downstream targets of the interleukin-1 receptor pathway, we show that p38 is required for the IL-1ß-mediated decrease in butyrate oxidation. These data provide insight into the metabolic effects induced by IL-1ß in colorectal cancer, and identify relevant targets that may be exploited to block the effects of this cytokine. J. Cell. Biochem. 118: 1614-1621, 2017. © 2016 Wiley Periodicals, Inc.

Soluble Epoxide Hydrolase Pharmacological Inhibition Decreases Alveolar Bone Loss by Modulating Host Inflammatory Response, RANK-Related Signaling, Endoplasmic Reticulum Stress, and Apoptosis.

Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid derived from the cytochrome P450 enzymes, are mainly metabolized by soluble epoxide hydrolase (sEH) to their corresponding diols. EETs but not their diols, have anti-inflammatory properties, and inhibition of sEH might provide protective effects against inflammatory bone loss. Thus, in the present study, we tested the selective sEH inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), in a mouse model of periodontitis induced by infection with Aggregatibacter actinomycetemcomitans Oral treatment of wild-type mice with TPPU and sEH knockout (KO) animals showed reduced bone loss induced by A. actinomycetemcomitans This was associated with decreased expression of key osteoclastogenic molecules, receptor activator of nuclear factor-κB/RANK ligand/osteoprotegerin, and the chemokine monocyte chemotactic protein 1 in the gingival tissue without affecting bacterial counts. In addition, downstream kinases p38 and c-Jun N-terminal kinase known to be activated in response to inflammatory signals were abrogated after TPPU treatment or in sEH KO mice. Moreover, endoplasmic reticulum stress was elevated in periodontal disease but was abrogated after TPPU treatment and in sEH knockout mice. Together, these results demonstrated that sEH pharmacological inhibition may be of therapeutic value in periodontitis.

Pancreatic Protein Tyrosine Phosphatase 1B Deficiency Exacerbates Acute Pancreatitis in Mice.

Acute pancreatitis (AP) is a common and devastating gastrointestinal disorder that causes significant morbidity. The disease starts as local inflammation in the pancreas that may progress to systemic inflammation and complications. Protein tyrosine phosphatase 1B (PTP1B) is implicated in inflammatory signaling, but its significance in AP remains unclear. To investigate whether PTP1B may have a role in AP, we used pancreas PTP1B knockout (panc-PTP1B KO) mice and determined the effects of pancreatic PTP1B deficiency on cerulein- and arginine-induced acute pancreatitis. We report that PTP1B protein expression was increased in the early phase of AP in mice and rats. In addition, histological analyses of pancreas samples revealed enhanced features of AP in cerulein-treated panc-PTP1B KO mice compared with controls. Moreover, cerulein- and arginine-induced serum amylase and lipase were significantly higher in panc-PTP1B KO mice compared with controls. Similarly, pancreatic mRNA and serum concentrations of the inflammatory cytokines IL-1B, IL-6, and tumor necrosis factor-α were increased in panc-PTP1B KO mice compared with controls. Furthermore, panc-PTP1B KO mice exhibited enhanced cerulein- and arginine-induced NF-κB inflammatory response accompanied with increased mitogen-activated protein kinases activation and elevated endoplasmic reticulum stress. Notably, these effects were recapitulated in acinar cells treated with a pharmacological inhibitor of PTP1B. These findings reveal a novel role for pancreatic PTP1B in cerulein- and arginine-induced acute pancreatitis.

Soluble epoxide hydrolase in podocytes is a significant contributor to renal function under hyperglycemia.

BACKGROUND: Diabetic nephropathy (DN) is the leading cause of renal failure, and podocyte dysfunction contributes to the pathogenesis of DN. Soluble epoxide hydrolase (sEH, encoded by Ephx2) is a conserved cytosolic enzyme whose inhibition has beneficial effects on renal function. The aim of this study is to investigate the contribution of sEH in podocytes to hyperglycemia-induced renal injury. MATERIALS AND METHODS: Mice with podocyte-specific sEH disruption (pod-sEHKO) were generated, and alterations in kidney function were determined under normoglycemia, and high-fat diet (HFD)- and streptozotocin (STZ)-induced hyperglycemia. RESULTS: sEH protein expression increased in murine kidneys under HFD- and STZ-induced hyperglycemia. sEH deficiency in podocytes preserved renal function and glucose control and mitigated hyperglycemia-induced renal injury. Also, podocyte sEH deficiency was associated with attenuated hyperglycemia-induced renal endoplasmic reticulum (ER) stress, inflammation and fibrosis, and enhanced autophagy. Moreover, these effects were recapitulated in immortalized murine podocytes treated with a selective sEH pharmacological inhibitor. Furthermore, pharmacological-induced elevation of ER stress or attenuation of autophagy in immortalized podocytes mitigated the protective effects of sEH inhibition. CONCLUSIONS: These findings establish sEH in podocytes as a significant contributor to renal function under hyperglycemia. GENERAL SIGNIFICANCE: These data suggest that sEH is a potential therapeutic target for podocytopathies.

Modulation of mitochondrial dysfunction and endoplasmic reticulum stress are key mechanisms for the wide-ranging actions of epoxy fatty acids and soluble epoxide hydrolase inhibitors.

The arachidonic acid cascade is arguably the most widely known biologic regulatory pathway. Decades after the seminal discoveries involving its cyclooxygenase and lipoxygenase branches, studies of this cascade remain an active area of research. The third and less widely known branch, the cytochrome P450 pathway leads to highly active oxygenated lipid mediators, epoxy fatty acids (EpFAs) and hydroxyeicosatetraenoic acids (HETEs), which are of similar potency to prostanoids and leukotrienes. Unlike the COX and LOX branches, no pharmaceuticals currently are marketed targeting the P450 branch. However, data support therapeutic benefits from modulating these regulatory lipid mediators. This is being approached by stabilizing or mimicking the EpFAs or even by altering the diet. These approaches lead to predominantly beneficial effects on a wide range of apparently unrelated states resulting in an enigma of how this small group of natural chemical mediators can have such diverse effects. EpFAs are degraded by soluble epoxide hydrolase (sEH) and stabilized by inhibiting this enzyme. In this review, we focus on interconnected aspects of reported mechanisms of action of EpFAs and inhibitors of soluble epoxide hydrolase (sEHI). The sEHI and EpFAs are commonly reported to maintain homeostasis under pathological conditions while remaining neutral under normal physiological conditions. Here we provide a conceptual framework for the unique and broad range of biological activities ascribed to epoxy fatty acids. We argue that their mechanism of action pivots on their ability to prevent mitochondrial dysfunction, to reduce subsequent ROS formation and to block resulting cellular signaling cascades, primarily the endoplasmic reticulum stress. By stabilizing the mitochondrial - ROS - ER stress axis, the range of activity of EpFAs and sEHI display an overlap with the disease conditions including diabetes, fibrosis, chronic pain, cardiovascular and neurodegenerative diseases, for which the above outlined mechanisms play key roles.