The results from this study showed that the thresholds of brainstem auditory-evoked potentials peak following 10 successive days of intramuscular injection of Roman chickens with kanamycin, starting 3 days after birth...The results from this study showed that the thresholds of brainstem auditory-evoked potentials peak following 10 successive days of intramuscular injection of Roman chickens with kanamycin, starting 3 days after birth. Fluorescence immunohistochemistry analysis revealed few ganglion cells positively labeled for Ephrin A2 in the cochlea of experimental chickens from 2 days before until 7 days after the last kanamycin injection. The number of Ephrin A2-positive ganglion cell bodies was increased at 15 days after the last injection and was similar to that in normal chickens at 30 days following the cessation of kanamycin treatment. These experimental findings indicate that Ephrin A2 protein expression in the acoustic ganglia is synchronized with the connection damage and regeneration of cochlear hair cells after kanamycin exposure. Ephrin A2 may play an important role in the regeneration and plasticity of cochlear hair cells in the chick cochlea following kanamycin ototoxicity.展开更多
Müller cells(MC) are considered dormant retinal progenitor cells in mammals.Previous studies demonstrated ephrin-As act as negative regulators of neural progenitor cells in the retina and brain.It remains unclear...Müller cells(MC) are considered dormant retinal progenitor cells in mammals.Previous studies demonstrated ephrin-As act as negative regulators of neural progenitor cells in the retina and brain.It remains unclear whether the lack of ephrin-A2/A3 is sufficient to promote the neurogenic potential of MC.Here we investigated whether the MC is the primary retinal cell type expressing ephrin-A2/A3 and their role on the neurogenic potential of Müller cells.In this study, we showed that ephrin-A2/A3 and their receptor EphA4 were expressed in retina and especially enriched in MC.The level of ephrin As/EphA4 expression increased as the retina matured that is correlated with the reduced proliferative and progenitor cell potential of MC.Next, we investigated the proliferation in primary MC cultures isolated from wild-type and A2~(–/–) A3~(–/–) mice by 5-ethynyl-2′-deoxyuridine(EdU) incorporation.We detected a significant increase of EdU~+ cells in MC derived from A2~(–/–) A3~(–/–) mice.Next, we investigated the role of ephrin-A2/A3 in mice undergoing photoreceptor degeneration such as Rhodopsin knockout(Rho~(–/–)) mice.To further evaluate the role of ephrin-A2/A3 in MC proliferation in vivo, EdU was injected intraperitoneally to adult wild-type, A2~(–/–) A3~(–/–), Rho~(–/–) and Rho~(–/–) A2~(–/–) A3~(–/–) mice and the numbers of EdU~+ cells distributed among different layers of the retina.Ephrin As/EphA4 expression was upregulated in the retina of Rho~(–/–) mice compared to the wild-type mice.In addition, cultured MC derived from ephrin-A2~(–/–) A3~(–/–) mice also expressed higher levels of progenitor cell markers and exhibited higher proliferation potential than those from wild-type mice.Interestingly, we detected a significant increase of EdU~+ cells in the retinas of adult ephrin-A2~(–/–) A3~(–/–) mice mainly in the inner nuclear layer;and these EdU~+ cells were co-localized with MC marker, cellular retinaldehyde-binding protein, suggesting some proliferating cells are from MC.In Rhodopsin knockout mice(Rho~(–/–) A2~(–/–) A3~(–/–) mice), a significantly greater amount of EdU~+ cells were located in the ciliary body, retina and RPE than that of Rho~(–/–) mice.Comparing between 6 and 12 weeks old Rho~(–/–) A2~(–/–) A3~(–/–) mice, we recorded more EdU~+ cells in the outer nuclear layer in the 12-week-old mice undergoing severe retinal degeneration.Taken together, Ephrin-A2/A3 are negative regulators of the proliferative and neurogenic potentials of MC.Absence of ephrin-A2/A3 promotes the migration of proliferating cells into the outer nuclear layer and may lead to retinal cell regeneration.All experimental procedures were approved by the Animal Care and Use Committee at Schepens Eye Research Institute, USA(approval No.S-353-0715) on October 24, 2012.展开更多
目的观察神经元-小胶质细胞间EphA4/ephrin信号通路在脑缺血后的炎性损伤中的作用及机制。方法建立神经元-小胶质细胞混合培养体系和糖氧剥夺再复氧(oxygen-glucose deprivation and reperfusion, OGD/R)模型,使用预聚集化的EphA4-Fc激...目的观察神经元-小胶质细胞间EphA4/ephrin信号通路在脑缺血后的炎性损伤中的作用及机制。方法建立神经元-小胶质细胞混合培养体系和糖氧剥夺再复氧(oxygen-glucose deprivation and reperfusion, OGD/R)模型,使用预聚集化的EphA4-Fc激动小胶质细胞ephrin配体,检测OGD/R后的细胞凋亡、小胶质细胞增殖和亚型极化以及小胶质细胞功能改变。结果 EphA4受体高表达于原代神经元,与对照组相比,预聚集化EphA4-Fc干预加重OGD/R导致的细胞凋亡,促进小胶质细胞增殖以及向M1型(促炎型)极化(炎症表型)。结论神经元-小胶质细胞间EphA4/ephrin信号通路通过调控小胶质细胞亚型极化参与脑缺血后的炎性损伤的过程。展开更多
基金supported by the Natural Science Foundation of Shanghai,No.08ZR1414900 and 11ZR1423600
文摘The results from this study showed that the thresholds of brainstem auditory-evoked potentials peak following 10 successive days of intramuscular injection of Roman chickens with kanamycin, starting 3 days after birth. Fluorescence immunohistochemistry analysis revealed few ganglion cells positively labeled for Ephrin A2 in the cochlea of experimental chickens from 2 days before until 7 days after the last kanamycin injection. The number of Ephrin A2-positive ganglion cell bodies was increased at 15 days after the last injection and was similar to that in normal chickens at 30 days following the cessation of kanamycin treatment. These experimental findings indicate that Ephrin A2 protein expression in the acoustic ganglia is synchronized with the connection damage and regeneration of cochlear hair cells after kanamycin exposure. Ephrin A2 may play an important role in the regeneration and plasticity of cochlear hair cells in the chick cochlea following kanamycin ototoxicity.
基金supported by the grants from Lion's Foundation Grant and Bright Focus Foundation(to KSC)the National Natural Science Foundation of China, No.81600727(to RLZ)。
文摘Müller cells(MC) are considered dormant retinal progenitor cells in mammals.Previous studies demonstrated ephrin-As act as negative regulators of neural progenitor cells in the retina and brain.It remains unclear whether the lack of ephrin-A2/A3 is sufficient to promote the neurogenic potential of MC.Here we investigated whether the MC is the primary retinal cell type expressing ephrin-A2/A3 and their role on the neurogenic potential of Müller cells.In this study, we showed that ephrin-A2/A3 and their receptor EphA4 were expressed in retina and especially enriched in MC.The level of ephrin As/EphA4 expression increased as the retina matured that is correlated with the reduced proliferative and progenitor cell potential of MC.Next, we investigated the proliferation in primary MC cultures isolated from wild-type and A2~(–/–) A3~(–/–) mice by 5-ethynyl-2′-deoxyuridine(EdU) incorporation.We detected a significant increase of EdU~+ cells in MC derived from A2~(–/–) A3~(–/–) mice.Next, we investigated the role of ephrin-A2/A3 in mice undergoing photoreceptor degeneration such as Rhodopsin knockout(Rho~(–/–)) mice.To further evaluate the role of ephrin-A2/A3 in MC proliferation in vivo, EdU was injected intraperitoneally to adult wild-type, A2~(–/–) A3~(–/–), Rho~(–/–) and Rho~(–/–) A2~(–/–) A3~(–/–) mice and the numbers of EdU~+ cells distributed among different layers of the retina.Ephrin As/EphA4 expression was upregulated in the retina of Rho~(–/–) mice compared to the wild-type mice.In addition, cultured MC derived from ephrin-A2~(–/–) A3~(–/–) mice also expressed higher levels of progenitor cell markers and exhibited higher proliferation potential than those from wild-type mice.Interestingly, we detected a significant increase of EdU~+ cells in the retinas of adult ephrin-A2~(–/–) A3~(–/–) mice mainly in the inner nuclear layer;and these EdU~+ cells were co-localized with MC marker, cellular retinaldehyde-binding protein, suggesting some proliferating cells are from MC.In Rhodopsin knockout mice(Rho~(–/–) A2~(–/–) A3~(–/–) mice), a significantly greater amount of EdU~+ cells were located in the ciliary body, retina and RPE than that of Rho~(–/–) mice.Comparing between 6 and 12 weeks old Rho~(–/–) A2~(–/–) A3~(–/–) mice, we recorded more EdU~+ cells in the outer nuclear layer in the 12-week-old mice undergoing severe retinal degeneration.Taken together, Ephrin-A2/A3 are negative regulators of the proliferative and neurogenic potentials of MC.Absence of ephrin-A2/A3 promotes the migration of proliferating cells into the outer nuclear layer and may lead to retinal cell regeneration.All experimental procedures were approved by the Animal Care and Use Committee at Schepens Eye Research Institute, USA(approval No.S-353-0715) on October 24, 2012.
