OBJECTIVE Astrocytic gap junctions formed by connexin 43(Cx43) are crucial for intercellular communication between spinal cord astrocytes. Various neurological disorders include chronic pain are associated with dysfun...OBJECTIVE Astrocytic gap junctions formed by connexin 43(Cx43) are crucial for intercellular communication between spinal cord astrocytes. Various neurological disorders include chronic pain are associated with dysfunctional Cx43-gap junctions. A previous study showed that treatment of spinal astrocytes in culture with pro-inflammatory cytokines tumor necrosis factor-α(TNF-α) and interferon-γ(IFN-γ) decreased both Cx43 expression and gap junction intercellular communication(GJIC)via a c-jun terminal kinase-dependent pathway. However,the exact mechanism that Cx43 does this in the context of spinal astrocytic dysfunction is unclear. The current study investigated the downstream signaling of Cx43-gap junction in rat primary cultured spinal astrocytes stimulated with cytokines.METHODS Wefocused on the glutamate transporters,examined the alteration of GLT-1 and glutamate-aspartate transporter(GLAST)expression and function in rat primary cultured spinal astrocytes stimulated with cytokines by real-time PCR and Western blotting. The function of GLT-1 was analyzed using the carbon 14. To elucidate the effect of Cx43 on glutamate transporters in spinal astrocytes,changes in glutamate transporters expression and function were quantified after Cx43 siRNA treatment.RESULTS The transcriptional and translational levels of Cx43 were reduced after 12 hr co-treatment with TNF-α(10 ng·mL^(-1)) or IFN-γ(5 ng·mL^(-1)). Furthermore,transcriptional and translational levels of GLT-1 and GLAST were also significantly reduced 24 and 48 h co-treatment with TNF-α or IFN-γ.Moreover,functional GLT-1 and GLAST uptake were inhibited by the mixture of TNF-α and IFN-γ. In addition,Both the decrease of GLT-1 expression and the reduction in functional GLT-1 uptake induced by the Cx43 si RNA,but both the expression and functional GLAST were no changes. CONCLUSION These results indicate that a Cx43 downregulation is induced under inflammatory condition that disrupts spinal astrocytic GLT-1 expression and function,leading to astrocytic dysfunction and the maintenance of the neuroinflammatory state.展开更多
Objective We performed experiments using Neuregulin-1β （NRG-1β） treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions （GJs） during heart failu...Objective We performed experiments using Neuregulin-1β （NRG-1β） treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions （GJs） during heart failure （HF）. Methods Rat models of I-IF were established by aortocaval fistula. Forty-eight rats were divided randomly into the HF （HF, n = 16）, NRG-1β trealanent （NRG, n = 16）, and sham operation （S, n = 16） group. The rats in the NRG group were administered NRG-1β （10 μg/kg per day） for 7 days via the tail vein, whereas the other groups were injected with the same doses of saline, Twelve weeks after operation, Connexin 43 （Cx43） expression in single myocytes obtained from the left ventricle was determined by immunocytochemistry. Total protein was extracted from frozen left ventricular tissues for immunoblotting assay, and the ultrastmcture of myocytes was observed by transmission electron microscopy. Results Compared with the HF group, the cardiac fimction of rats in the NRG group was markedly improved, irregular distribution and deceased Cx43 expression were relieved. The ultrastmcture of myocytes was seriously damaged in HF rats, and NRG-1β reduced these pathological damages. Conclusions Short-term NRG-1β treatment can rescue pump failure in experimental models of volume overload-induced HF, which is related to the recovery of GJs structure and the improvement of Cx43 expression.展开更多
Adipose tissue is a promising target for treating obesity and metabolic diseases.However,pharmacological agents usually fail to effectively engage adipocytes due to their extraordinarily large size and insufficient va...Adipose tissue is a promising target for treating obesity and metabolic diseases.However,pharmacological agents usually fail to effectively engage adipocytes due to their extraordinarily large size and insufficient vascularization,especially in obese subjects.We have previously shown that during cold exposure,connexin43(Cx43)gap junctions are induced and activated to connect neighboring adipocytes to share limited sympathetic neuronal input amongst multiple cells.We reason the same mechanism may be leveraged to improve the efficacy of various pharmacological agents that target adipose tissue.Using an adipose tissue-specific Cx43 overexpression mouse model,we demonstrate effectiveness in connecting adipocytes to augment metabolic efficacy of theβ_(3)-adrenergic receptor agonist Mirabegron and FGF21.Additionally,combing those molecules with the Cx43 gap junction channel activator danegaptide shows a similar enhanced efficacy.In light of these findings,we propose a model in which connecting adipocytes via Cx43 gap junction channels primes adipose tissue to pharmacological agents designed to engage it.Thus,Cx43 gap junction activators hold great potential for combination with additional agents targeting adipose tissue.展开更多
文摘OBJECTIVE Astrocytic gap junctions formed by connexin 43(Cx43) are crucial for intercellular communication between spinal cord astrocytes. Various neurological disorders include chronic pain are associated with dysfunctional Cx43-gap junctions. A previous study showed that treatment of spinal astrocytes in culture with pro-inflammatory cytokines tumor necrosis factor-α(TNF-α) and interferon-γ(IFN-γ) decreased both Cx43 expression and gap junction intercellular communication(GJIC)via a c-jun terminal kinase-dependent pathway. However,the exact mechanism that Cx43 does this in the context of spinal astrocytic dysfunction is unclear. The current study investigated the downstream signaling of Cx43-gap junction in rat primary cultured spinal astrocytes stimulated with cytokines.METHODS Wefocused on the glutamate transporters,examined the alteration of GLT-1 and glutamate-aspartate transporter(GLAST)expression and function in rat primary cultured spinal astrocytes stimulated with cytokines by real-time PCR and Western blotting. The function of GLT-1 was analyzed using the carbon 14. To elucidate the effect of Cx43 on glutamate transporters in spinal astrocytes,changes in glutamate transporters expression and function were quantified after Cx43 siRNA treatment.RESULTS The transcriptional and translational levels of Cx43 were reduced after 12 hr co-treatment with TNF-α(10 ng·mL^(-1)) or IFN-γ(5 ng·mL^(-1)). Furthermore,transcriptional and translational levels of GLT-1 and GLAST were also significantly reduced 24 and 48 h co-treatment with TNF-α or IFN-γ.Moreover,functional GLT-1 and GLAST uptake were inhibited by the mixture of TNF-α and IFN-γ. In addition,Both the decrease of GLT-1 expression and the reduction in functional GLT-1 uptake induced by the Cx43 si RNA,but both the expression and functional GLAST were no changes. CONCLUSION These results indicate that a Cx43 downregulation is induced under inflammatory condition that disrupts spinal astrocytic GLT-1 expression and function,leading to astrocytic dysfunction and the maintenance of the neuroinflammatory state.
基金This research was supported by the Key Program，the National Natural Science Foundation of China
文摘Objective We performed experiments using Neuregulin-1β （NRG-1β） treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions （GJs） during heart failure （HF）. Methods Rat models of I-IF were established by aortocaval fistula. Forty-eight rats were divided randomly into the HF （HF, n = 16）, NRG-1β trealanent （NRG, n = 16）, and sham operation （S, n = 16） group. The rats in the NRG group were administered NRG-1β （10 μg/kg per day） for 7 days via the tail vein, whereas the other groups were injected with the same doses of saline, Twelve weeks after operation, Connexin 43 （Cx43） expression in single myocytes obtained from the left ventricle was determined by immunocytochemistry. Total protein was extracted from frozen left ventricular tissues for immunoblotting assay, and the ultrastmcture of myocytes was observed by transmission electron microscopy. Results Compared with the HF group, the cardiac fimction of rats in the NRG group was markedly improved, irregular distribution and deceased Cx43 expression were relieved. The ultrastmcture of myocytes was seriously damaged in HF rats, and NRG-1β reduced these pathological damages. Conclusions Short-term NRG-1β treatment can rescue pump failure in experimental models of volume overload-induced HF, which is related to the recovery of GJs structure and the improvement of Cx43 expression.
基金supported in part by a research grant from Novo Nordsik(USA,to Philipp E.Scherer)by NIH Grants(USA)R01-DK55758,R01-DK099110,R01-DK127274,R01DK131537 and P01-AG051459 to Philipp E.Scherer,NIH Grant R00-DK114498+4 种基金NIH Grant K99-AG068239 to Shangang ZhaoNIH Grant K01-DK125447 to Yu A.AnNIH grants R01 DK119169 and P01 DK119130-5830 to Kevin W.WilliamsUSDA ARS(cooperative agreement 309251000-062)to Yi ZhuAHA Career Development Award 855170(USA)to Qingzhang Zhu。
文摘Adipose tissue is a promising target for treating obesity and metabolic diseases.However,pharmacological agents usually fail to effectively engage adipocytes due to their extraordinarily large size and insufficient vascularization,especially in obese subjects.We have previously shown that during cold exposure,connexin43(Cx43)gap junctions are induced and activated to connect neighboring adipocytes to share limited sympathetic neuronal input amongst multiple cells.We reason the same mechanism may be leveraged to improve the efficacy of various pharmacological agents that target adipose tissue.Using an adipose tissue-specific Cx43 overexpression mouse model,we demonstrate effectiveness in connecting adipocytes to augment metabolic efficacy of theβ_(3)-adrenergic receptor agonist Mirabegron and FGF21.Additionally,combing those molecules with the Cx43 gap junction channel activator danegaptide shows a similar enhanced efficacy.In light of these findings,we propose a model in which connecting adipocytes via Cx43 gap junction channels primes adipose tissue to pharmacological agents designed to engage it.Thus,Cx43 gap junction activators hold great potential for combination with additional agents targeting adipose tissue.
