OBJECTIVE: To investigate the mechanism by which doublecortin promotes the recovery of cytoskeleton in arginine vasopressin (AVP) neurons in rats with electrical lesions of the pituitary stalk (PEL). METHODS: Thirty-two SD rats were randomized into PEL group with electrical lesions of the pituitary stalk through the floor of the skull base (=25) and sham operation group (=7), and the daily water consumption (DWC), daily urine volume (DUV) and urine specific gravity (USG) of the rats were recorded. Four rats on day 1 and 7 rats on each of days 3, 7 and 14 after PEL as well as the sham-operated rats were sacrificed for detection of the expressions of β-Tubulin (Tuj1), doublecortin and caspase- 3 in the AVP neurons of the supraoptic nucleus using immunofluorescence assay and Western blotting. RESULTS: After PEL, the rats exhibited a typical triphasic pattern of diabetes insipidus, with the postoperative days 1-2 as the phase one, days 3-5 as the phase two, and days 6-14 as the phase three. Immunofluorescent results indicated the repair of the AVP neurons evidenced by significantly increased doublecortin expressions in the AVP neurons following PEL; similarly, the expression of Tuj1 also increased progressively after PEL, reaching the peak level on day 7 after PEL. The apoptotic rates of the AVP neurons exhibited a reverse pattern of variation, peaking on postoperative day 3 followed by progressive reduction till day 14. Western blotting showed that the expressions of c-Jun and p-c-Jun were up-regulated significantly on day 3 ( < 0.05) and 7 ( < 0.01) after PEL, while an upregulated p-JNK expression was detected only on day 3 ( < 0.05), as was consistent with the time-courses of neuronal recovery and apoptosis after PEL. CONCLUSIONS JNK/c-Jun pathway is activated after PEL to induce apoptosis of AVP neurons in the acute phase and to promote the repair of neuronal cytoskeleton by up-regulation of doublecortin and Tuj1 expressions.
Animals ; Apoptosis ; Arginine Vasopressin ; pharmacology ; Cytoskeleton ; metabolism ; MAP Kinase Signaling System ; Neurons ; cytology ; Pituitary Gland ; cytology ; injuries ; Proto-Oncogene Proteins c-jun ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Regeneration ; Tubulin ; metabolism

PURPOSE: Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms. MATERIALS AND METHODS: Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin. RESULTS: Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation. CONCLUSION: Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation.
Animals ; Aorta ; Arginase* ; Arginine ; Blotting, Western ; Bromodeoxyuridine ; Cell Proliferation* ; Chromatography, High Pressure Liquid ; Chromatography, Liquid ; Lipoproteins ; Luminescence ; Membranes ; Muscle, Smooth, Vascular* ; NADP* ; NADPH Oxidase* ; Phosphorylation ; Phosphotransferases ; Protein Kinase C ; Rats ; Reactive Oxygen Species ; Superoxides

BACKGROUND: Arginine vasopressin (AVP) is widely used as a vasopressor agent. Some recent studies have suggested that AVP may exert an immunomodulatory effect. However, the mechanism about the anti-inflammatory effect of AVP is not well known. We investigated the effect of AVP on the ihibitor of kappa B (IkappaBalpha)/nuclear factor-kappa B (NF-kappaB) pathway in RAW 264.7 cells. METHODS: Cultured RAW 264.7 cells were pretreated with AVP and stimulated with lipopolysaccharide (LPS). To evaluate the effect of AVP on inflammatory cytokines, the concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by an enzyme-linked immunosorbent assay technique. The expression of IkappaBalpha and nuclear translocation of NF-kappaB p65 were measured by Western blotting, and IkappaB kinase (IKK) activity was analyzed by an in vitro immune complex kinase assay. To confirm the AVP effect on IkappaBalpha/NF-kappaB cascade and via V2 receptor, we added tolvaptan (V2 receptor antagonist) after AVP pretreatment. RESULTS: The increase of IL-6 and TNF-alpha in LPS-stimulated RAW 264.7 cells was suppressed by a treatment with AVP. Pretreatment of AVP inhibited increasing of IKK activity and IkappaBalpha degradation induced by LPS in RAW 264.7 cells. Furthermore, LPS induced and NF-kappaB transcription was inhibited by AVP pretreatment. The observed changes in IKK activity, IkappaBalpha degradation and NF-kappaB transcription by AVP was abolished by tolvaptan treatment. CONCLUSIONS: Our results suggest that AVP showed anti-inflammatory effect on LPS-induced IkappaBalpha/NF-kappaB cascade in mouse macrophages via V2 receptors.
Animals ; Antigen-Antibody Complex ; Arginine Vasopressin ; Blotting, Western ; Cytokines ; Enzyme-Linked Immunosorbent Assay ; I-kappa B Kinase ; Interleukin-6 ; Macrophages ; Mice ; NF-kappa B ; Phosphotransferases ; Receptors, Vasopressin ; Tumor Necrosis Factor-alpha

Hypernatremia is a rare cause of rhabdomyolysis. Here, we report a case of hypernatremia-induced rhabdomyolysis in a patient with meningioma involving the pituitary gland. A 61-year-old male was admitted for decreased mentality and poor oral intake. He had undergone an operation for meningioma 10 years prior. At admission, he appeared lethargic and severely dehydrated with an initial sodium level of 178 mEq/L. Hypernatremia remained persistent despite massive hydration and the serum creatine phosphokinase level was 18,047 U/L after 3 days. Bone scintigraphy also showed findings consistent with rhabdomyolysis. Brain magnetic resonance imaging revealed extensive masses involving the pituitary gland and an intranasal biopsy confirmed meningioma. Polyuria, and low anti-diuretic hormone levels supported the diagnosis of central diabetes insipidus-induced hypernatremia. Desmopressin was administered intranasally and the patient's serum sodium and muscle enzyme levels were normalized.
Biopsy ; Brain ; Creatine Kinase ; Deamino Arginine Vasopressin ; Diabetes Insipidus ; Diagnosis ; Humans ; Hypernatremia ; Magnetic Resonance Imaging ; Male ; Meningioma* ; Middle Aged ; Pituitary Gland* ; Polyuria ; Radionuclide Imaging ; Rhabdomyolysis* ; Sodium

Crab meat is a valuable source of proteins and functional lipids and it is widely consumed worldwide. However, the prevalence of crab allergy has increased over the past few years. In order to understand crab allergy better, it is necessary to identify crab allergens. The aim of the present study was to compare the IgEbinding proteins of raw and cooked extracts of mud crab (Scylla serrata). Raw and cooked extracts of the mud crab were prepared. Protein profiles and IgE reactivity patterns were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting using sera from 21 skin prick test (SPT) positive patients. In SDS-PAGE, 20 protein bands (12 to 250 kDa) were observed in the raw extract while the cooked extract demonstrated fewer bands. Protein bands between 40 to 250 kDa were sensitive to heat denaturation and no longer observed in the cooked extract. In immunoblotting experiments, raw and cooked extracts demonstrated 11 and 4 IgE-binding proteins, respectively, with molecular weights of between 23 and 250 kDa. A heat-resistant 36 kDa protein, corresponding to crab tropomyosin was identified as the major allergen of both extracts. In addition, a 41 kDa heat-sensitive protein believed to be arginine kinase was shown to be a major allergen of the raw extract. Other minor allergens were also observed at various molecular weights.
Arginine Kinase

BACKGROUND: Arginine vasopressin (AVP) is widely used as a vasopressor agent. Some recent studies have suggested that AVP may exert an immunomodulatory effect. However, the mechanism about the anti-inflammatory effect of AVP is not well known. We investigated the effect of AVP on the ihibitor of kappa B (IkappaBalpha)/nuclear factor-kappa B (NF-kappaB) pathway in RAW 264.7 cells. METHODS: Cultured RAW 264.7 cells were pretreated with AVP and stimulated with lipopolysaccharide (LPS). To evaluate the effect of AVP on inflammatory cytokines, the concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by an enzyme-linked immunosorbent assay technique. The expression of IkappaBalpha and nuclear translocation of NF-kappaB p65 were measured by Western blotting, and IkappaB kinase (IKK) activity was analyzed by an in vitro immune complex kinase assay. To confirm the AVP effect on IkappaBalpha/NF-kappaB cascade and via V2 receptor, we added tolvaptan (V2 receptor antagonist) after AVP pretreatment. RESULTS: The increase of IL-6 and TNF-alpha in LPS-stimulated RAW 264.7 cells was suppressed by a treatment with AVP. Pretreatment of AVP inhibited increasing of IKK activity and IkappaBalpha degradation induced by LPS in RAW 264.7 cells. Furthermore, LPS induced and NF-kappaB transcription was inhibited by AVP pretreatment. The observed changes in IKK activity, IkappaBalpha degradation and NF-kappaB transcription by AVP was abolished by tolvaptan treatment. CONCLUSIONS: Our results suggest that AVP showed anti-inflammatory effect on LPS-induced IkappaBalpha/NF-kappaB cascade in mouse macrophages via V2 receptors.
Animals ; Antigen-Antibody Complex ; Arginine Vasopressin ; Blotting, Western ; Cytokines ; Enzyme-Linked Immunosorbent Assay ; I-kappa B Kinase ; Interleukin-6 ; Macrophages ; Mice ; NF-kappa B ; Phosphotransferases ; Receptors, Vasopressin ; Tumor Necrosis Factor-alpha

Protein arginine methylation is important for a variety of cellular processes including transcriptional regulation, mRNA splicing, DNA repair, nuclear/cytoplasmic shuttling and various signal transduction pathways. However, the role of arginine methylation in protein biosynthesis and the extracellular signals that control arginine methylation are not fully understood. Basic fibroblast growth factor (bFGF) has been identified as a potent stimulator of myofibroblast dedifferentiation into fibroblasts. We demonstrated that symmetric arginine dimethylation of eukaryotic elongation factor 2 (eEF2) is induced by bFGF without the change in the expression level of eEF2 in mouse embryo fibroblast NIH3T3 cells. The eEF2 methylation is preceded by ras-raf-mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK1/2)-p21(Cip/WAF1) activation, and suppressed by the mitogen-activated protein kinase (MAPK) inhibitor PD98059 and p21(Cip/WAF1) short interfering RNA (siRNA). We determined that protein arginine methyltransferase 7 (PRMT7) is responsible for the methylation, and that PRMT5 acts as a coordinator. Collectively, we demonstrated that eEF2, a key factor involved in protein translational elongation is symmetrically arginine-methylated in a reversible manner, being regulated by bFGF through MAPK signaling pathway.
Animals ; Arginine ; Cell Dedifferentiation ; Cyclin-Dependent Kinase Inhibitor p21/genetics/metabolism ; Elongation Factor 2 Kinase/*metabolism ; Fibroblast Growth Factor 2/*metabolism ; Fibroblasts/*metabolism/pathology ; Flavonoids/pharmacology ; MAP Kinase Signaling System/drug effects/genetics ; Methylation ; Mice ; Mitogen-Activated Protein Kinases/antagonists & inhibitors ; Myofibroblasts/pathology ; NIH 3T3 Cells ; Protein Methyltransferases/*metabolism ; Protein-Arginine N-Methyltransferases/*metabolism ; RNA, Small Interfering/genetics

Protein arginine methylation is important for a variety of cellular processes including transcriptional regulation, mRNA splicing, DNA repair, nuclear/cytoplasmic shuttling and various signal transduction pathways. However, the role of arginine methylation in protein biosynthesis and the extracellular signals that control arginine methylation are not fully understood. Basic fibroblast growth factor (bFGF) has been identified as a potent stimulator of myofibroblast dedifferentiation into fibroblasts. We demonstrated that symmetric arginine dimethylation of eukaryotic elongation factor 2 (eEF2) is induced by bFGF without the change in the expression level of eEF2 in mouse embryo fibroblast NIH3T3 cells. The eEF2 methylation is preceded by ras-raf-mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK1/2)-p21(Cip/WAF1) activation, and suppressed by the mitogen-activated protein kinase (MAPK) inhibitor PD98059 and p21(Cip/WAF1) short interfering RNA (siRNA). We determined that protein arginine methyltransferase 7 (PRMT7) is responsible for the methylation, and that PRMT5 acts as a coordinator. Collectively, we demonstrated that eEF2, a key factor involved in protein translational elongation is symmetrically arginine-methylated in a reversible manner, being regulated by bFGF through MAPK signaling pathway.
Animals ; Arginine ; Cell Dedifferentiation ; Cyclin-Dependent Kinase Inhibitor p21/genetics/metabolism ; Elongation Factor 2 Kinase/*metabolism ; Fibroblast Growth Factor 2/*metabolism ; Fibroblasts/*metabolism/pathology ; Flavonoids/pharmacology ; MAP Kinase Signaling System/drug effects/genetics ; Methylation ; Mice ; Mitogen-Activated Protein Kinases/antagonists & inhibitors ; Myofibroblasts/pathology ; NIH 3T3 Cells ; Protein Methyltransferases/*metabolism ; Protein-Arginine N-Methyltransferases/*metabolism ; RNA, Small Interfering/genetics

OBJECTIVETo determine the role of asymmetric dimethylarginine (ADMA) in acute lung injury induced by cerebral ischemia/reperfusion (I/R) injury in rats.

METHODSAdult male SD rats were randomly divided into 4 groups, namely the sham-operated group (S), cerebral I/R model group, ADMA+I/R group, and dimethylarginine dimethylaminohydrolase (DDAH)+I/R group. In the latter 3 groups, acute lung injury was induced by left middle cerebral artery occlusion for 120 min. After a 24-h reperfusion, the rats were sacrificed and the activities of nitric oxide synthase (NOS) and contents of nitric oxide (NO) were measured using reductase and colorimetric assay. The mRNA and protein expressions of protein kinase C (PKC) and myosin light chain kinase (MLCK) in the lung tissues were detected with RT-PCR and Western blotting, respectively. The contents of ADMA in the bronchoalveolar lavage fluid (BALF) and blood flowing into and out of the lungs were measured by ELISA.

RESULTSCerebral I/R injury caused significantly elevated ADMA levels in the BALF and blood flowing into the lungs, and obviously lowered the NO concentration and NOS activity in the lung tissues (P<0.05). Following cerebral I/R injury, MLCK and PKC mRNA and protein expressions were significantly upregualted in the lung tissues (P<0.05). Exogenous DDAH obviously decreased the levels of ADMA in the BALF and blood flowing into the lungs, increased NO concentration and NOS activity, and down-regulated MLCK and PKC mRNA and protein expressions in lung tissues of rats with cerebral I/R injury (P<0.05).

CONCLUSIONADMA contributes to the development of acute lung injury following cerebral I/R injury in rats by upregulating MLCK and PKC expression. ADMA may serve as a novel therapeutic biomarker and a potential therapeutic target for acute lung injury induced by cerebral I/R injury.

Acute Lung Injury ; etiology ; physiopathology ; Animals ; Arginine ; analogs & derivatives ; metabolism ; pharmacology ; Brain Ischemia ; complications ; Male ; Myosin-Light-Chain Kinase ; genetics ; metabolism ; Nitric Oxide Synthase ; antagonists & inhibitors ; Protein Kinase C ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; complications ; physiopathology ; Up-Regulation ; drug effects

Akt (protein kinase B (PKB)) is a serine/threonine kinase that acts in the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. The PI3K/Akt signaling pathway, triggered by growth factors and hormones including vasopressin, is an important pathway that is widely involved in cellular mechanisms regulating transcription, translation, cell growth and death, cell proliferation, migration, and cell cycles. In particular, Akt and Akt substrate protein of 160 kDa (AS160) are likely to participate in the trafficking of aquaporin-2 (AQP2) in the kidney collecting duct. In this study, we demonstrated that 1) small interfering RNA (siRNA)-mediated gene silencing of Akt1 significantly decreased Akt1 and phospho-AS160 protein expression; and 2) confocal laser scanning microscopy of AQP2 in mouse cortical collecting duct cells (M-1 cells) revealed AS160 knockdown by siRNA increased AQP2 expression in the plasma membrane compared with controls, despite the absence of dDAVP stimulation. Thus, the results suggest that PI3K/Akt pathways could play a role in AQP2 trafficking via the AS160 protein.
Animals ; Aquaporin 2 ; Cell Cycle ; Cell Death ; Cell Membrane ; Deamino Arginine Vasopressin ; Gene Silencing ; Intercellular Signaling Peptides and Proteins ; Kidney Tubules, Collecting ; Membranes ; Mice ; Microscopy, Confocal ; Phosphatidylinositol 3-Kinase ; Phosphotransferases ; Protein Transport ; Proto-Oncogene Proteins c-akt ; rab GTP-Binding Proteins ; RNA, Small Interfering ; Vasopressins ; Water