Influence of Ren and Du meridian electro-acupuncture on neural stem cell proliferation and extracellular signal-regulated kinase pathway in a rat model of focal cerebral ischemia injury

BACKGROUND： Studies have shown that electro-acupuncture at the Ren meridian could improve proliferation of subventricular zone neural stem cells in cerebral-ischemic rats. However, there are few reports on the influence of electro-acupuncture at the Du meridian on neural stem cell proliferation. OBJECTIVE： To observe the influence of electro-acupuncture at Ren and Du meridians on neural stem cell proliferation in the subventricular zone and altered signal transduction in cerebral ischemia rats. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Laboratory of Human Anatomy, Medical College of Sun Yat-sen University from May 2006 to February 2008. MATERIALS： Mouse anti-rat bromodeoxyuridine （BrdU） monoclonal antibody was provided by Sigma, USA; mouse anti-rat nestin monoclonal antibody and extracellular signal-regulated protein kinase （ERK） specific inhibitor PD98059 were provided by Calbiochem, Germany; acupuncture needle was provided by Suzhou Acupuncture Supplies, China. METHODS： A total of 126 rats were randomly assigned to four groups： model （n = 36）, Du meridian （n = 36）, Ren/Du meridian （n = 36）, and Ren/Du meridian ＋ PD98059 （n = 18）. Rats in the Ren/Du meridian ＋ PD98059 group were observed on days 7 （n = 6） and 14 （n = 12） after cerebral ischemia injury. Rats in the model, Du meridian, and Ren/Du meridian groups were observed on days 7, 14, and 28 after cerebral ischemia injury, with 12 rats per group at each time point. Thread occlusion was used to establish middle cerebral artery occlusion models. Electro-acupuncture was performed at Renzhong （DU 26） and Baihui （DU 20） acupoints in the Du meridian group, as well as Chengjiang （RN 24）, Guanyuan （RN 4）, Renzhong, and Baihuiacupoints in the Ren/Du meridian and Ren/Du meridian ＋ PD98059 groups 2 days after model establishment. In addition, electro-acupuncture stimulation with disperse-dense waves was performed, with 30 Hz disperse wave, 100 Hz dense wave, and 5 V intensity for 20 minutes. Rats in the Ren/Du meridian ＋ PD98059 group were treated with 0.2 pg PD98059 injection into the subventricular zone, 2 pL per rat. Rats in the model group were not treated with electro-acupuncture. MAIN OUTCOME MEASURES： BrdU/nestin immunofluorescent staining was used to detect proliferating neural stem cells in the subventricular zone of cerebral ischemia rats; Western blot was used to determine phosphorylated ERK1 and 2 （pERK1/2） expression in the subventricular zone. RESULTS： On days 14 and 28 after cerebral ischemia, there were significantly more BrdU-positive and BrdU/nestin-positive cells in the Ren/Du meridian group compared with the Du meridian group （P 〈 0.05）. PD98059 decreased the number of BrdU-positive and BrdU/nestin-positive cells induced by electro-acupuncture at the/：ten and Du meridians （P 〈 0.05）. On days 7, 14, and 28 after treatment, pERK1/2 expression was significantly greater in the Du meridian and Ren/Du meridian groups compared with the model group （P 〈 0.05）. The promoting effect of electro-acupuncture at Ren and Du meridians on ERK1/2 phosphorylation was superior to electro-acupuncture at the Du meridian alone on day 14 after model induction （P 〈 0.05）. However, PD98059 completely abolished the promoting effect of electro-acupuncture at Ren/Du meridians on pERK1/2 expression （P 〈 0.05）. CONCLUSION： Electro-acupuncture at Ren and Du meridians increased proliferation of subventricular zone neural stem cells, which was related to activation of the ERK pathway in a rat model of cerebral ischemia injury.

An experimental study of extracellular signal-regulated kinase and its interventional treatments in hepatic fibrosis

BACKGROUND: The pathogenesis of hepatic fibrosis and cirrhosis is still not fully understood. The extracellular signal-regulated kinase (ERK) pathway is involved in the regulation of cell proliferation and differentiation. The aim of this study was to investigate the effects of PD98059, a specific inhibitor of ERK, on the cell cycle, cell proliferation, secretion of type I collagen and expression of cyclin D1 mRNA, CDK4 mRNA and transforming growth factor-beta 1 (TGF-beta 1) mRNA in rat hepatic stellate cells (HSCs) stimulated by acetaldehyde. METHODS: Rat HSCs stimulated by acetaldehyde were incubated with PD98059 at different concentrations. The cell cycle was analysed by flow cytometry. Cell proliferation was assessed by the methyl thiazolyl tetrazolium colorimetric assay. The mRNA expression of cyclin D1, CDK4 and TGF-beta 1 was examined using the reverse transcriptase-polymerase chain reaction. Type I collagen in the culture medium was detected by enzyme-linked immunosorbent assay. RESULTS: 20, 50 and 100 mu mol/L PD98059 significantly inhibited the proliferation and provoked a G0/G1-phase arrest of acetaldehyde-induced HSCs in a dose-dependent manner. The secretion of type I collagen and the expression of cyclin D1, CDK4 and TGF-beta 1 mRNA in acetaldehyde-induced HSCs were markedly inhibited by 50 and 100 mu mol/L PD98059, respectively. CONCLUSIONS: The ERK pathway regulates the cell proliferation, secretion of type I collagen and the expression of TGF-beta 1 mRNA in rat HSCs stimulated by acetaldehyde, which is likely related to its regulative effect on the cell cycle.

Regulation of extracellular signal-regulated kinase 1/2 influences hippocampal neuronal survival in a rat model of diabetic cerebral ischemia

Activation of extracellular signal-regulated kinase 1/2 has been demonstrated in acute brain ischemia. We hypothesized that activated extracellular signal-regulated kinase 1/2 can protect hippocampal neurons from injury in a diabetic model after cerebral ischemia/reperfusion. In this study, transient whole-brain ischemia was induced by four-vessel occlusion in normal and diabetic rats, and extracellular signal-regulated kinase 1/2 inhibitor （U0126） was administered into diabetic rats 30 minutes before ischemia as a pretreatment. Results showed that the number of surviving neurons in the hippocampal CA1 region was reduced, extracellular signal-regulated kinase 1/2 phosphorylation and KuT0 activity were decreased, and pro-apoptotic Bax expression was upregulated after intervention using U0126. These findings demonstrate that inhibition of extracellular signal-regulated kinase 1/2 activity aggravated neuronal loss in the hippocampus in a diabetic rat after cerebral ischemia/reperfusion, further decreased DNA repairing ability and ac- celerated apoptosis in hippocampal neurons. Extracellular signal-regulated kinase 1/2 activation plays a neuroprotective role in hippocampal neurons in a diabetic rat after cerebral ischemia/ reperfusion.

Pterygium epithelium abnormal differentiation related to activation of extracellular signal-regulated kinase signaling pathway in vitro

AIMTo investigate whether the abnormal differentiation of the pterygium epithelium is related to the extracellular signal-regulated kinase (ERK) signaling pathway in vitro.METHODSThe expression levels of phosphorylated ERK (P-ERK), keratin family members including K19 and K10 and the ocular master control gene Pax-6 were measured in 16 surgically excised pterygium tissues and 12 eye bank conjunctiva. In colony-forming cell assays, the differences in clone morphology and in K10, K19, P-ERK and Pax-6 expression between the head and body were investigated. When cocultured with the ERK signaling pathway inhibitor PD98059, the changes in clone morphology, colony-forming efficiency, differentiated marker K10, K19 and Pax-6 expression and P-ERK protein expression level were examined by immunoreactivity and Western blot analysis.RESULTSThe expression of K19 and Pax-6 decreased in the pterygium, especially in the head. No staining of K10 was found in the normal conjunctiva epithelium, but it was found to be expressed in the superficial cells in the head of the pterygium. Characteristic upregulation of P-ERK was observed by immunohistochemistry. The clone from the head with more differentiated cells in the center expressed more K10, and the clone from the body expressed more K19. The P-ERK protein level increased in the pterygium epithelium compared with conjunctiva and decreased when cocultured with PD98059. The same medium with the ERK inhibitor PD98059 was more effective in promoting clonal growth than conventional medium with 3T3 murine feeder layers. It was observed that the epithelium clone co-cultured with the inhibitor had decreased K10 expression and increased K19 and Pax-6 expression.CONCLUSIONWe suggest ERK signaling pathway activation might play a role in the pterygium epithelium abnormal differentiation.

Extracellular signal-regulated kinase, substance P and neurokinin-1 are involved in the analgesic mechanism of herb-partitioned moxibustion

Herb-partitioned moxibustion can effectively mitigate visceral pain, a major symptom in inflammatory bowel disease, but the analgesic lnechanism is still unclear. Moreover, extracellular signal-regulated kinase, substance P, and neurokinin-1 are involved in formation of central hyperalgesia. Thus, we postulated that the analgesic effect of herb-partitioned moxibustion may be associated with these factors. Accordingly, in this study, we established an inflammatory bowel disease visceral pain model in rat by enema with a mixed solution of 5% trinitrobenzenesulfonic acid and 50% ethanol. Bilateral Tianshu （ST25） and Qihai （CV6） points were selected for herb-partitioned moxi- bustion. Our results showed that herb-partitioned moxibustion improved visceral pain and down-regulated extracellular signal-regulated kinase, substance P, and neurokinin-1 protein and mRNA expression in dorsal root ganglia. These results indicate that down-regulation of extracellular signal-regulated kinase, substance E and neurokinin-1 protein and mRNA may be a central mechanism for the analgesic effect of herb-partitioned moxibustion.

Effect of extracellular signal-regulated kinase and nitric oxide on compressive neuralgia formation and maintenance

BACKGROUND： Previous studies have shown that extracellular signal-regulated kinase 1/2 （ERK1/2） and nitric oxide activation play a pivotal role in central sensitization and long-term neuronal plasticity induced by noxious stimulation. However, their effects on compressive neuralgia formation and maintenance remain poorly understood.OBJECTIVE： To investigate effects of the specific inhibitor of ERK1/2 signal pathway U0126 on neuronal nitric oxide synthase （nNOS） expression in the dorsal horn of the spinal cord in a compressive neuralgia rat model.DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed at the Institute of Otolaryngology, Head and Neck Surgery, First Hospital of Jilin University from July 2008 to March 2009.MATERIALS： U0126 （Bio-Mol, USA） was used in this study.METHODS： A total of 84 rats were randomly assigned to two groups. In the first part of the experiment, 24 rats were used for behavioral testing, and they were randomly assigned to three sub-groups （n =8）： U0126, dimethyl sulfoxide （DMSO） and model control. In the second part of the experiment, 60 rats were used for immunofluorescence and Western blot analysis, and they were randomly assigned to six sub-groups （n = 10）： sham surgery, model control, U0126 post-injection at 0.5, 2, 12 and 24 hours. Neuropathic pain was produced by chronic compression to the dorsal root ganglion in rats from each sub-group. Rats in the U0126 group were administered a 5-ug U0126 intrathecal injection, and rats in the DMSO group were administered a 10-μL 5% DMSO intrathecal injection.MAIN OUTCOME MEASURES： Changes in mechanical and thermal hyperalgesia were observed using von Frey filaments and thermalqia stimular. Thermal and mechanical hyperalgesia were stimulated at different time points following intrathecal injection of U0126. nNOS activation and expression in the spinal cord dorsal horn were determined by immunofluorescence and Western blot analysis.RESULTS： Intrathecal injection of U0126 significantly attenuated chronic compression of dorsal root ganglion-induced mechanical and thermal hyperalgesia. Immunofluorescence staining results demonstrated that, compared to the sham surgery group, the number of nNOS-positive neurons was significantly increased in the injured spinal dorsal horn in the model control group （P〈0.01）. However, compared to the model control group, there were significantly decreasing numbers of nNOS-positive neurons in the U0126 post-injection groups at 0.5-hour, 2-hour, and 12-hour （P〈0.05）. Western blot analysis revealed similar results. CONCLUSION： Decreased activity in the ERK signal pathway resulted in down regulated nNOS expression in the dorsal horn of the spinal cord. These results suggested that ERK is involved in nitric oxide reaction to neuropathic pain.

Dexamethasone suppresses DU145 cell proliferation and cell cycle through inhibition of the extracellular signal-regulated kinase 1 /2 pathway and cyclin D1 expression

Aim： To determine the mechanisms of glucocorticoids in inhibiting advanced prostate cancer growth. Methods： The cell proliferation and cell cycle of prostate cancer DU145 cells following dexamethasone treatment were determined by proliferation assay and fluorescence-activated cell sorter. Western blot analysis was carried out to evaluate the effects of dexamethasone on phosphorylation of extracellular signal-regulated kinase （ERK）1/2 and expression of cyclin D1 in DU145 cells with or without glucocorticoid receptor （GR） antagonist RU486. Reverse transcription- polymerase chain reaction verified the expression of GR mRNA in DU145 cells. Results： Dexamethasone significantly inhibited DU 145 cell proliferation at the G0/G1 phase. Westem blot analysis showed a dramatic reduction of ERK1/2 activity and cyclin D1 expression in dexamethasone-treated cells. The decreased phosphorylation of ERK1/2 in dexamethasone-treated cells was attenuated by GR blockade. Additionally, the effects of dexamethasone in inhibiting cyclin D1 expression were altered by GR blockade. Conclusion： Dexamethasone suppresses DU145 cell proliferation and cell cycle, and the underlying mechanisms are through the inhibition of phosphorylation of ERK1/2 and cyclin D1 expression. The inhibition of ERK1/2 phosphorylation and cyclin D1 expression is attenuated by GR blockade, suggesting that GR regulates ERK1/2 and cyclin D1 pathways. These observations suggest that dexamethasone has a potential clinical application in prostate cancer therapy.

Neurotransmitter regulation of extracellular signal-regulated kinase expression following subarachnoid hemorrhage

BACKGROUND： Very few studies have addressed neuronal injury in cerebral vasospasm and subarachnoid hemorrhage （SAH）, and the role of neurotransmitters in the regulation of extracellular signal-regulated kinase 1/2 （ERK1/2） expression following SAH. OBJECTIVE： To analyze neurotransmitter regulation of ERK1/2 expression through the use of signal transduction, and to investigate cerebral injury mechanisms following SAH. DESIGN, TIME AND SETTING： A completely randomized grouping and controlled animal experiment was performed at the Experimental Center of Medical College of Xi＇an Jiaotong University from March to December 2008. MATERIALS： Extraceliular signal-regulated ERK1/2 polyclonal antibody and streptavidin-peroxidase method kits were purchased from Beijing Biosynthesis Biotechnology, China; DAB kit was purchased from Zhongshan Golden Bridge Biotechnology, China; TUNEL kit was purchased from Promega, USA. METHODS： A total of 114 male, Sprague Dawley rats, aged 55-63 days old, were randomly assigned to five groups： SAH （n = 30）, saline control （n = 30）, puncture control （n = 30）, normal control （n = 6）, and neurotransmitter-treated （n = 18）. The SAH model was established by twice injecting blood through the cisterna magna. The neurotransmitters-treated group was subdivided into three groups according to drugs injected into the lateral cerebral ventricle： acetylcholine chloride, norepinephrine, and saline, with six animals in each group. MAIN OUTCOME MEASURES： Rats from the SAH, saline control, and puncture control groups were respectively sacrificed at 6, 12, and 24 hours, as well as 3 and 5 days, with six rats at each time point. The normal control group rats were sacrificed at 6 hours, and the neurotransmitter group rats were sacrificed 3 days following neurotransmitter injection. Morphological cellular changes were observed by hematoxylin and eosin staining. Immunohistochemical SP method was used to detect expression of ERK1/2 in the cortex, and cortical apoptosis was detected using the TUNEL method. RESULTS： Neural tissue edema, apoptosis, and necrosis occurred in the cortex of the SAH group. ERK1/2-positive cells were first observed at 6 hours, peaked at 12 hours following SAH in the cortex, and gradually decreased thereafter. Cellular apoptosis was observed in the cortex at 6 hours and peaked at 24 hours following SAH. ERK1/2 distribution in the brain overlapped apoptotic cells to a great degree. The number of ERK1/2-positive and apoptotic cells was significantly greater in the SAH group compared with the three control groups （P 〈 0.05）. Compared to the number of ERK1/2-positive cells in the saline-treated group, acetylcholine chloride treatment resulted in decreased ERK1/2 expression and apoptosis （P 〈 0.05）. Norepinephrine resulted in increased ERK1/2 expression, but there was no significance in apoptosis compared to the saline-treated group （P 〉 0.05）. CONCLUSION： Apoptosis was observed early in the rat cortex following SAH. In addition, ERK1/2 was expressed earlier than apoptosis. Acetylcholine chloride treatment resulted in decreased numbers of apoptotic cells following SAH, possibly by down-regulating ERK1/2 expression.

Downregulation of Aquaporin 4 Expression through Extracellular Signal-regulated Kinases1/2 Activation in Cultured Astrocytes Following Scratch-injury

Objective To investigate the role of extracellular signal-regulated kinase1/2（ERK1/2） pathway in the regulation of aquaporin 4（AQP4） expression in cultured astrocytes after scratch-injury. Methods The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase（LDH） leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2（p-ERK1/2） expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 μmol/L U0126（ERK1/2 inhibitor） was incubated in the medium at 30 min before the scratch-injury in some groups. Results Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury. Conclusion These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.

OVER-EXPRESSION OF EXTRACELLULAR SIGNAL-REGULATED KINASE IN VASCULAR SMOOTH MUSCLE CELL OF HYPERTENSIVE RATS

Objective To investigate whether extracellular signal-regulated kinase (ERK1/2) was involved in changes of vascular smooth muscle cell (VSMC) under hypertension.Methods Two-kidney one clip Wistar hypertensive rats (WHR) were sacrificed and their right kidneys were harvested 4 weeks after surgery.The spontaneously hypertensive rats (SHR) were divided into 4, 8, and 16 weeks old groups (SHR4w, SHR8w, and SHR16w), respectively.The control group were sham operated age-matched Wistar rats.Immunohistochemical technique and Western blotting were applied to study ERK1/2 protein expression in VSMC of the renal vascular trees in WHR, SHR, and control rats.Results Blood pressure in two-kidney one clip WHR obviously increased at one week after surgery, and reached to 198.00±33.00 mm Hg at the end of experiment, significantly higher than that in the control rats (P<0.01).Blood pressure in SHR4w (108.00±11.25 mm Hg) was similar to that in the controls.However, it rose to 122.25±21.75 mm Hg in SHR8w, and even up to 201.75±18.00 mm Hg in SHR16w, which were significantly higher than that of both the SHR4w and the controls (P<0.01).The rate and degree of glomerular fibrosis in WHR were significantly higher than controls (P<0.05).Hyaline degeneration of the afferent arterioles was found in WHR.In contrast, either fibrosis of glomerulus or hyaline degeneration of the arterioles or protein casts was not observed in SHR4w, SHR8w, and SHR16w.Immunohistochemical staining results showed expression of ERK1 was similar to that of ERK2.The positive rates of ERK2 staining in VSMC of afferent arterioles, interlobular, interlobar, and arcuate arteries in two-kidney one clip WHR were significantly higher (7.09%±1.75%, 14.57%±4.58%, 29.44%±7.35%, and 13.63%±3.85%, respectively) than that of the controls(P<0.01).The positive rates of ERK2 staining in VSMC at afferent arterioles, interlobular, interlobar, and arcuate arteries in SHR16w were significantly higher (12.09%±1.40%, 24.17%±6.92%, 32.44%±4.05%, and 18.61%±3.35%, respectively) than that of the controls (P<0.01), too.The expression of ERK1/2 protein of kidney in WHR and SHR16w was significantly higher than that in the controls by Western blotting assay (P<0.01).Conclusion Extracellular signal transduction system are highly expressed in kidney VSMC of two-kidney one clip WHR and SHR.Phospho-ERK1/2 may play an important role in VSMC hypertrophy and hyperplasia under hypertension.

Time-dependent effects of electroacupuncture at the Ren channel on extracellular signal-regulated kinases 1/2 expression in focal cerebral ischemia rats

BACKGROUND： The onset of focal cerebral ischemia activates extracellular signal-regulated kinases 1 and 2, regulates cell cycle, promotes cell proliferation and differentiation, and affects the normal stage and function of brain cells. OBJECTIVE： To observe the effects of electroacupuncture at the Ren channel on extracellular signal-regulated kinases 1/2 expression in the lateral cerebral ventricle wall of rats with focal cerebral ischemia. The effects were analyzed at different time points after intervention. DESIGN： Randomized controlled study. SETTING： Department of Anatomy, Sun Yat-Sen University. MATERIALS： A total of 60 healthy adult male Wistar rats weighing （250±10） g were provided by the Experimental Animal Center, Medical College of Sun Yat-Sen University. The animal experiment was conducted with confirmed consent by the local ethics committee. The GB6805-Ⅱ electric acupuncture apparatus was provided by Shanghai Medical Equipment High-techno Company. METHODS： The experiment was performed at the Laboratory of Anatomy, Sun Yat-Sen University, from February to July 2007. All experimental animals were randomly divided into the following groups： normal group （n = 6）, sham operation group （n = 18）, model group （n = 18）, and electroacupuncture group （n = 18）. Middle cerebral artery occlusion （MCAO） was performed in the model group and electroacupuncture group. Zea Longa＇s grading standard was used to assess neurological impairment after reperfusion; animals whose grades were between l and 4 were included in this study. The normal control group was not exposed to MCAO. In sham operation animals, the right common carotid artery （CCA） was isolated, and the external carotid artery （ECA） was damaged, but no embolism was induced. The electroacupuncture group was given acupuncture on the second day after surgery. The acupoint locations were chosen according to Experimental Acupuncture （People＇s Publishing House; 1997; First Edition）. The Chengjiang, Qihai, and Guanyuan acupoints were labeled and connected to a G6805 electroacupuncture apparatus with sparse-dense waves （sparse waves were 30 Hz, dense waves were 100 Hz）, with a frequency of 6-15 V. The duration was 20 minutes. Two days after surgery, the model and sham operation groups were placed with their backs on the operating table, but they received no acupuncture. However, the normal group received acupuncture. The experimental animals under anesthesia were sacrificed on days 7, 14, and 28 post-surgery. Western blot analysis was used to measure expression of extracellular signal-regulated kinases 1/2 in the inferior region of the lateral cerebral ventricle wall. Expression was measured in the normal group at time points corresponding to the sham operation group. MAIN OUTCOME MEASURES： Expression of extracellular signal-regulated kinases 1/2 in the inferior region of the lateral cerebral ventricle wall at different time points after intervention. RESULTS： All 60 rats were included in the final analysis, without any loss. Seven days after MCAO, there was no significant difference in extracellular signal-regulated kinases 1/2 expression in the electroacupuncture group compared to the model group （P 〉 0.05）. However, extracellular signal-regulated kinases 1/2 expression significantly increased in the model group at 14 and 28 days after treatment （P 〈 0.05）. CONCLUSION： Electroacupuncture at the Ren channel can enhance extracellular signal-regulated kinasesl/2 expression in the inferior region of the lateral cerebral ventricle wall of rats with focal cerebral ischemia. However, this effect is not apparent until 14 days after electroacupuncture intervention.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Overexpression of mitogen-activated protein kinase phosphatase-1 in endothelial cells reduces blood-brain barrier injury in a mouse model of ischemic stroke

Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.

Gan Shen Fu Fang ameliorates liver fibrosis in vitro and in vivo by inhibiting the inflammatory response and extracellular signalregulated kinase phosphorylation

BACKGROUND Liver fibrosis is a common health problem worldwide and there is still a lack of effective medicines.The Chinese herbal medicine,Gan Shen Fu Fang(GSFF)is composed of salvianolic acid B and diammonium glycyrrhizinate.In this study,we observed the effects of GSFF on liver fibrosis in vivo and in vitro in an attempt to provide some hope for the treatment.AIM To observe the effects of GSFF on liver fibrosis in vivo and in vitro and investigate the mechanism from the perspective of the inflammatory response and extracellular signal-regulated kinase(ERK)phosphorylation.METHODS Common bile duct-ligated rats were used for in vivo experiments.Hepatic stellate cells-T6(HSC-T6)cells were used for in vitro experiments.Hematoxylin and eosin staining and Masson staining,biochemical assays,hydroxyproline(Hyp)assays,enzyme-linked immunoasorbent assay and western blotting were performed to evaluate the degree of liver fibrosis,liver function,the inflammatory response and ERK phosphorylation.The CCK8 assay,immunofluorescence and western blotting were applied to test the effect of GSFF on HSC-T6 cell activation and determine whether GSFF had an effect on ERK phosphorylation in HSC-T6 cells.RESULTS GSFF improved liver function and inhibited liver fibrosis in common bile ductligated rats after 3 wk of treatment,as demonstrated by histological changes,hydroxyproline assays and collagen I concentrations.GSFF alleviated inflammatory cell infiltration and reduced the synthesis of pro-inflammatory cytokines[tumor necrosis factor-α(TNF-α)and interlukin-1β]and NF-κB.In addition,GSFF decreased ERK phosphorylation.In vitro,GSFF inhibited the viability of HSC-T6 cells with and without transforming growth factorβ1(TGF-β1)stimulation and decreased the synthesis of collagen I.GSFF had the greatest effect at a concentration of 0.5μmol/L.GSFF inhibited the expression ofα-smooth muscle actin(α-SMA),a marker of HSC activation,in HSC-T6 cells.Consistent with the in vivo results,GSFF also inhibited the phosphorylation of ERK and downregulated the expression of NF-κB.CONCLUSION GSFF inhibited liver fibrosis progression in vivo and HSC-T6 cell activation in vitro.These effects may be related to an alleviated inflammatory response and downregulated ERK phosphorylation.

线粒体内膜蛋白17(MPV17)通过阻断ERK通路抑制铁过载小鼠脾脏CD3^(+)T细胞铁死亡

目的探索铁过载对小鼠脾脏损伤的影响及线粒体内膜蛋白17(MPV17)在铁过载小鼠脾脏CD3^(+)T细胞铁死亡中的作用。方法将小鼠随机分为正常饮食组、高铁饮食组、高铁饮食联合铁死亡抑制剂ferrostatin-1(Fer-1)处理组、高铁饮食联合MPV17腺病毒注射组,每组5只。喂食8周后,取脾脏组织并固定,通过组织切片和HE染色法观察脾脏结构,碘化丙啶(PI)染色检测脾脏CD3^(+)T细胞死亡,脂质过氧化荧光探针C11 BODIPY 581/591检测脂质氧化,实时定量PCR检测溶质载体家族7成员11(SLC7A11)及前列腺素内过氧化物合成酶2(PTGS2)mRNA水平,流式细胞术检测M1、M2巨噬细胞比例,ELISA实验检测肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)及IL-6的含量。同时增加高铁饮食联合细胞外信号调节激酶(ERK)抑制剂处理组、ERK激活剂处理组、β半乳糖苷(β-gal)酶联合ERK激活剂处理组、MPV17联合ERK激活剂处理组,Western blot法检测MPV17、谷胱甘肽过氧化物酶4(GPX4)、磷酸化的ERK(p-ERK)水平,JC-1结合流式细胞术检测线粒体膜电位。结果与正常饮食组相比,高铁饮食组小鼠脾脏红髓形状不规则,白髓结构消失,脾脏CD3^(+)T细胞死亡增多,脂质过氧化物增多,SLC7A11及PTGS2表达升高,血液中M1/M2巨噬细胞比例升高,炎症因子含量升高;经Fer-1处理或过表达MPV17,部分恢复脾脏结构,CD3^(+)T细胞数量及脂质过氧化物减少,SLC7A11及PTGS2表达被抑制,M1/M2巨噬细胞比例及炎症因子的含量降低。高铁饮食导致GPX4表达降低,p-ERK表达升高,抑制ERK部分恢复GPX4表达,激活ERK降低GPX4表达;MPV17抑制ERK部分恢复GPX4表达,MPV17部分恢复因ERK激活导致的线粒体膜电势降低。结论铁过载可诱导小鼠脾脏CD3^(+)T细胞发生铁死亡,MPV17通过阻断ERK信号抑制高铁饮食诱导的脾脏CD3^(+)T细胞铁死亡。

连翘脂素调节Ras/Raf/MEK/ERK信号通路对结直肠癌细胞恶性生物学行为的影响

目的 探究连翘脂素(PG)对结直肠癌细胞增殖、迁移、侵袭、凋亡以及上皮间质转化的影响及机制。方法 培养HCT116结直肠癌细胞,采用10~200μmol/L的连翘脂素处理细胞,检测细胞存活率,筛选最佳实验浓度。将细胞分为对照组(Control组),连翘脂素低、中、高浓度组(PG-L组、PG-M组、PG-H组),连翘脂素高浓度+转染慢病毒阴性对照组(PG-H+NC组),连翘脂素高浓度+Ras慢病毒组(PG-H+Ras组)。平板克隆形成实验检测细胞增殖;划痕实验检测细胞迁移;Transwell小室法检测细胞侵袭;流式细胞术以及Hoechst33258染色法检测细胞凋亡;Western blot法检测上皮间质转化(EMT)标志蛋白E型钙黏蛋白(E-cadherin)、波形蛋白(Vimentin)以及信号通路相关蛋白p-Raf、p-MEK、p-ERK表达;建立荷瘤小鼠模型评价连翘脂素对结直肠癌肿瘤生长的影响。结果 10~200μmol/L的连翘脂素处理HCT116结直肠癌细胞,可以显著抑制细胞存活率,经计算IC50值为(140.4±2.147)μmol/L,选择10、50、100μmol/L连翘脂素进行后续实验;与Control组比较,PG-L组、PG-M组、PG-H组HCT116细胞克隆形成率、划痕愈合率、细胞侵袭个数以及Vimentin、p-Raf、p-MEK、p-ERK表达显著降低,细胞凋亡率以及E-cadherin表达显著升高,且呈浓度依赖性(P<0.05);与PG-H+NC组比较,PG-H+Ras组HCT116细胞克隆形成率、划痕愈合率、细胞侵袭个数以及Vimentin、p-Raf、p-MEK、p-ERK表达显著升高,细胞凋亡率以及E-cadherin表达显著降低(P<0.05);连翘脂素可以显著抑制结直肠癌移植瘤的生长。结论 连翘脂素可以抑制结直肠癌细胞增殖、迁移、侵袭、凋亡以及上皮间质转化,其作用机制可能与抑制Ras/Raf/MEK/ERK信号通路激活有关。

Serine-threonine protein kinase activation may be an effective target for reducing neuronal apoptosis after spinal cord injury

The signaling mechanisms underlying ischemia-induced nerve cell apoptosis are poorly understood. We investigated the effects of apoptosis-related signal transduction pathways following ischemic spinal cord injury, including extracellular signal-regulated kinase（ERK）, serine-threonine protein kinase（Akt） and c-Jun N-terminal kinase（JNK） signaling pathways. We established a rat model of acute spinal cord injury by inserting a catheter balloon in the left subclavian artery for 25 minutes. Rat models exhibited notable hindlimb dysfunction. Apoptotic cells were abundant in the anterior horn and central canal of the spinal cord. The number of apoptotic neurons was highest 48 hours post injury. The expression of phosphorylated Akt（pAkt） and phosphorylated ERK（p-ERK） increased immediately after reperfusion, peaked at 4 hours（p-Akt） or 2 hours（p-ERK）, decreased at 12 hours, and then increased at 24 hours. Phosphorylated JNK expression reduced after reperfusion, increased at 12 hours to near normal levels, and then showed a downward trend at 24 hours. Pearson linear correlation analysis also demonstrated that the number of apoptotic cells negatively correlated with p-Akt expression. These findings suggest that activation of Akt may be a key contributing factor in the delay of neuronal apoptosis after spinal cord ischemia, particularly at the stage of reperfusion, and thus may be a target for neuronal protection and reduction of neuronal apoptosis after spinal cord injury.

利用FRET技术检测不同力学条件下T细胞中ERK活性的脉冲现象

目的探索Jurkat T细胞中胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)活性动力学以及基质刚度对ERK活性的影响。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时观测Jurkat细胞中ERK活性的变化,或细胞处于I型胶原基质胶中检测其影响。结果部分Jurkat细胞中存在ERK活性脉冲现象,频率约为3次/h,FRET振幅变化约为20%。在抗体激活T细胞抗原受体(T-cell receptor,TCR)的条件下,ERK脉冲依然存在,频率和振幅无显著变化。当细胞处于I型胶原水凝胶中,随着胶基质刚度增加,脉冲频率有所下调。结论Jurkat T细胞中存在自发的ERK活性脉冲现象,初步实验显示其频率受基质刚度影响。而该信号波动的生理意义和分子机制仍有待探索。

Response of Subcutaneous Xenografts of Endometrial Cancer in Nude Mice to Inhibitors of Phosphatidylinositol 3-Kinase/Akt and Mitogen-Activated Protein Kinase (MAPK) Pathways: An Effective Therapeutic Strategy for Endometrial Cancer

Objective: This study was designed to explore whether inhibition of the extracellular-regulated kinase (ERK) and phosphatidylinositol-3-kinase (PI3K) signaling pathways can inhibit the growth of xenografts of endometrial cancer cell lines with different estrogen receptors (ER) profiles in vivo and to provide preliminary laboratory basis for the probability of endometrial adenocarcinoma treatment with blockage of the two pathways, especially to endometrial cancer with low ER status. Methods: Human endometrial cancer Ishikawa bearing ER and HEC-1Awith low ER status cells were subcutaneously injected into BALB/c nude mice to establish endometrial cancer xenograft tumor models. The effects of PI3K/Akt inhibitor LY294002, MAPK/ERK1/2 inhibitor PD-98059 and their combinations on the growth of the xenograft tumors and apoptotic state of Ishikawa and HEC-1Acells were tested in vivo using the inhibitory rate, the terminal deoxynucleotidyl transferase-mediated nick-end labeling assay, H/E-stain. Western blot analysis was used to detect the alterations of activated ERK (P-ERK) and AKT (P-AKT) during this process. Results: LY294002, a PI3K/Akt pathway inhibitor, induced significant suppression in the growth of both Ishikawa and HEC-1Acell xenograft tumors, concomitant with increased apoptosis in xenografts as evidenced by TUNEL. A similar effect was also observed when the MAPK/ERK1/2 signaling pathway was inhibited by PD98059. Concurrent inhibition of the PI3K/Akt and MAPK/ERK1/2 pathways showed enhanced anti-tumor effects in vivo as indicated by increased apoptosis. At the same time, the levels of P-ERK and P-AKT in both xenograft tumors decreased, and their levels in combination group was the lowest. Conclusions: PD98059, LY294002 and their combinations showed remarkable inhibitory effects on xenograft tumors of endometrial carcinoma cell lines with different expression status of ER in vivo through blockage of PI3K/Akt and MAPK/ERK1/2 signaling pathways. This suggests that targeting these pathways may be an effective therapeutic strategy against endometrial carcinomas, especially for ER-negative cancers which show poor response to endocrinal therapy.

Role of the extracellular signal-regulated kinase 1/2 signaling pathway in regulating the secretion of bronchial smooth muscle cells in a rat model of chronic asthma

Background Although it is recognized that bronchial smooth muscle cells （BSMCs） play a key role. in airway remodeling during chronic asthma, it is not well understood how BSMCs exert their inflammatory functions. The extracellular signal-regulated kinase 1/2 （ERK1/2） signaling pathway is an important signaling pathway in chronic asthma but its influence on secretion by BSMCs has not been well-studied. We investigated the impact of ERK1/2 signaling pathway on secretion by BSMCs in a rat model of chronic asthma in this study. Methods To create a rat model of chronic asthma, Wistar rats underwent ovalbumim （OVA） injection and eight weeks of inhalation. BSMCs were isolated and cultured in vitro. Epidermal growth factor, PD98059 and ERK1/2 antisense oligonucleotide were used to explore the role of ERK1/2 signaling pathway. The expression of P-ERK1/2 （phospho-ERK1/2） in BSMCs was analyzed by Western blot and reverse transcriptase-polymerase chain reaction （RT-PCR）. Secretion of BSMCs was detected by enzyme-linked immunosorbent assay （ELISA）. Results Phospho-ERK1/2 expression was increased in BSMCs of chronic asthmatic rats compared with the controls. PD98059 inhibited expression of phospho-ERK1/2 protein, while treatment with an antisense oligonucleotide inhibited the expression of P-ERK1/2 mRNA and protein. BSMCs obtained from the chronic asthma group secreted significantly greater quantities of growth factors （transforming growth factor （TGF）-β1, vascular endothelial growth factor （VEGF） and connective tissue growth factor （CTGF））, cytokines （regulated upon activation, normal T cell-expressed and secreted （RANTES） and eotaxin）, and extracellular matrix （fibronectin and collagen I） compared with normal controls. Epidermal growth factor stimulated secretion in both groups, but the response of the chronic asthma group was more intense. Both PD98059 and antisense oligonucleotide suppressed secretion by BSMCs in chronic ashmatic rats. Antisense oligonucleotide reduced the level of RANTES nearly to that of normal controls, while PD98059 could not. Conclusion These results suggest that ERK1/2 signaling pathway may play an important role in the augmented secretion of BSMCs in chronic asthmatic rats. and ERK1/2 antisense oligonucleotide effectively inhibits the process.