The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechani...The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechanisms responsible for initiating spontaneous ATP release have not been determined.Our previous study revealed that telomerase reverse transcriptase(TERT)is expressed in the basilar membrane during the first postnatal week.Its role in cochlear development remains unclear.In this study,we investigated the expression and role of TERT in postnatal cochlea supporting cells.Our results revealed that in postnatal cochlear Kölliker’s organ supporting cells,TERT shifts from the nucleus into the cytoplasm over time.We found that the TERT translocation tendency in postnatal cochlear supporting cells in vitro coincided with that observed in vivo.Further analysis showed that TERT in the cytoplasm was mainly located in mitochondria in the absence of oxidative stress or apoptosis,suggesting that TERT in mitochondria plays roles other than antioxidant or anti-apoptotic functions.We observed increased ATP synthesis,release and activation of purine signaling systems in supporting cells during the first 10 postnatal days.The phenomenon that TERT translocation coincided with changes in ATP synthesis,release and activation of the purine signaling system in postnatal cochlear supporting cells suggested that TERT may be involved in regulating ATP release and activation of the purine signaling system.Our study provides a new research direction for exploring the spontaneous electrical activity of the cochlea during the early postnatal period.展开更多
目的观察离体活膀胱肌条铺片中卡哈尔间质细胞(interstitial cells of cajal,ICCs)自发性钙瞬变,并检测胞外钙及胞内钙库钙对ICCs细胞自发性钙瞬变的影响,探讨ICCs细胞自发性钙瞬变产生的机制。方法制作离体膀胱肌条铺片,生理液灌流保...目的观察离体活膀胱肌条铺片中卡哈尔间质细胞(interstitial cells of cajal,ICCs)自发性钙瞬变,并检测胞外钙及胞内钙库钙对ICCs细胞自发性钙瞬变的影响,探讨ICCs细胞自发性钙瞬变产生的机制。方法制作离体膀胱肌条铺片,生理液灌流保持肌条铺片活性。待肌条自发性收缩活动出现后,Fluo-4负载肌条铺片,激光共聚焦显微镜观察其中ICCs细胞自发性钙瞬变,随后观察尼莫地平(Nimodipine)、2-氨基乙基二苯硼酸盐(2-aminoethoxydip henylborate,2-APB)、雷诺丁(Ryanodine)、毒胡萝卜素(Thapsigargin)及无钙、高钙生理液对ICCs细胞自发性钙瞬变的影响,探讨ICCs细胞自发性钙瞬变产生的机制。结果可见离体活膀胱肌条铺片中平滑肌细胞和ICCs细胞均产生节律性自发性钙瞬变,平滑肌细胞钙瞬变频率较快,而ICCs细胞钙瞬变频率相对较慢。尼莫地平能完全抑制平滑肌细胞的自发性钙瞬变,但对ICCs细胞的自发性钙瞬变无显著影响。2-APB、雷诺丁、毒胡萝卜素及无钙生理液均可完全抑制ICCs细胞的自发性钙瞬变,高钙生理液可显著增加ICCs细胞自发性钙瞬变的频率。结论细胞外钙离子通过非L型钙离子通道入胞及细胞内钙库放钙均参与ICCs细胞自发性钙瞬变的产生。展开更多
Calcium ions are important in many vital neuron processes, including spontaneous neurotransmitter release. Extracellular calcium has long been known to be related to spontaneous neurotransmitter release, but the detai...Calcium ions are important in many vital neuron processes, including spontaneous neurotransmitter release. Extracellular calcium has long been known to be related to spontaneous neurotransmitter release, but the detailed mechanism for the effect of intracellular Ca^2+ on synaptic release has not yet been understood. In this research, 1,2-bis-(o-aminophenoxy)-ethane-N, N, N′, N′-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM) was used to combine with cytosolic free Ca^2+ in a calcium free medium of cultured Xenopus neuromuscular junctions (NMJ), The spontaneous synaptic current (SSC) frequency was obviously reduced. Then, drugs were applied to interrupt and activate the Ca2+ release channels in the endoplasmic reticulum (ER) membrane, but the SSC frequency was not affected. The results show that spontaneous neurotransmitter release depends on intracellular rather than ER calcium in cultured Xenopus NMJ without extracellular calcium.展开更多
Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryoni...Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryonic stem cells),multipotent(hematopoietic stem cells,multipotent adult progenitor stem cells,and mesenchymal stem cells[MSCs]),and unipotent(progenitor cells that differentiate into a single lineage)cells.Though bone marrow is the primary source of multipotent stem cells in adults,other tissues such as adipose tissues,placenta,amniotic fluid,umbilical cord blood,periodontal ligament,and dental pulp also harbor stem cells that can be used for regenerative therapy.In addition,induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells,and thus could be another source for regenerative medicine.Several diseases including neurodegenerative diseases,cardiovascular diseases,autoimmune diseases,virus infection(also coronavirus disease 2019)have limited success with conventional medicine,and stem cell transplantation is assumed to be the best therapy to treat these disorders.Importantly,MSCs,are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair.Moreover,MSCs have the potential to migrate towards the damaged area,which is regulated by various factors and signaling processes.Recent studies have shown that extracellular calcium(Ca^(2+))promotes the proliferation of MSCs,and thus can assist in transplantation therapy.Ca^(2+)signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors,Ca^(2+)channels/pumps/exchangers,Ca^(2+)buffers,and Ca^(2+)sensors,which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity,which will be discussed in this review.展开更多
Spontaneous secretions occur in both neurons and non-neuronal cells, and calcium is important for these secretion processes. However, the detailed roles of calcium on the secretions have not yet been identified. In th...Spontaneous secretions occur in both neurons and non-neuronal cells, and calcium is important for these secretion processes. However, the detailed roles of calcium on the secretions have not yet been identified. In the present study, cultured Xenopus myocytes loaded with exogenous acetylcholine (ACh) into the cytoplasm in the absence of extracellular Ca^2+ undergo spontaneous quantal ACh secretion as detected by the appearance of pulsatile miniature endplate currents. Analysis of the frequencies, amplitudes, and time courses of these currents suggests that similar cellular mechanisms are involved in the secretions of ACh in normal medium and Ca^2+-free solution. Various doses of ryanodine were used to regulate the intra- cellular Ca^2+ to different levels. The spontaneous ACh secretion from myocytes in Ca^2+-free medium was decreased by reducing intracellular Ca^2+ levels and enhanced by increasing cytosolic Ca^2+ levels. These observations demonstrate that the spontaneous secretion from isolated myocytes and the effect of ryanodine on ACh-loaded cells are both independent of extracellular Ca^2+ while Ca^2+ in the sarcoplasmic reticulum plays a crucial role in the secretions.展开更多
基金supported by the National Natural Science Foundation of China,Nos.81870732(to DZ),82171161(to DZ),81900933(to YS),and 82000978(to ZL).
文摘The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechanisms responsible for initiating spontaneous ATP release have not been determined.Our previous study revealed that telomerase reverse transcriptase(TERT)is expressed in the basilar membrane during the first postnatal week.Its role in cochlear development remains unclear.In this study,we investigated the expression and role of TERT in postnatal cochlea supporting cells.Our results revealed that in postnatal cochlear Kölliker’s organ supporting cells,TERT shifts from the nucleus into the cytoplasm over time.We found that the TERT translocation tendency in postnatal cochlear supporting cells in vitro coincided with that observed in vivo.Further analysis showed that TERT in the cytoplasm was mainly located in mitochondria in the absence of oxidative stress or apoptosis,suggesting that TERT in mitochondria plays roles other than antioxidant or anti-apoptotic functions.We observed increased ATP synthesis,release and activation of purine signaling systems in supporting cells during the first 10 postnatal days.The phenomenon that TERT translocation coincided with changes in ATP synthesis,release and activation of the purine signaling system in postnatal cochlear supporting cells suggested that TERT may be involved in regulating ATP release and activation of the purine signaling system.Our study provides a new research direction for exploring the spontaneous electrical activity of the cochlea during the early postnatal period.
文摘目的观察离体活膀胱肌条铺片中卡哈尔间质细胞(interstitial cells of cajal,ICCs)自发性钙瞬变,并检测胞外钙及胞内钙库钙对ICCs细胞自发性钙瞬变的影响,探讨ICCs细胞自发性钙瞬变产生的机制。方法制作离体膀胱肌条铺片,生理液灌流保持肌条铺片活性。待肌条自发性收缩活动出现后,Fluo-4负载肌条铺片,激光共聚焦显微镜观察其中ICCs细胞自发性钙瞬变,随后观察尼莫地平(Nimodipine)、2-氨基乙基二苯硼酸盐(2-aminoethoxydip henylborate,2-APB)、雷诺丁(Ryanodine)、毒胡萝卜素(Thapsigargin)及无钙、高钙生理液对ICCs细胞自发性钙瞬变的影响,探讨ICCs细胞自发性钙瞬变产生的机制。结果可见离体活膀胱肌条铺片中平滑肌细胞和ICCs细胞均产生节律性自发性钙瞬变,平滑肌细胞钙瞬变频率较快,而ICCs细胞钙瞬变频率相对较慢。尼莫地平能完全抑制平滑肌细胞的自发性钙瞬变,但对ICCs细胞的自发性钙瞬变无显著影响。2-APB、雷诺丁、毒胡萝卜素及无钙生理液均可完全抑制ICCs细胞的自发性钙瞬变,高钙生理液可显著增加ICCs细胞自发性钙瞬变的频率。结论细胞外钙离子通过非L型钙离子通道入胞及细胞内钙库放钙均参与ICCs细胞自发性钙瞬变的产生。
基金Supported by the Natural Science Foundation of Beijing (No. 5052015)
文摘Calcium ions are important in many vital neuron processes, including spontaneous neurotransmitter release. Extracellular calcium has long been known to be related to spontaneous neurotransmitter release, but the detailed mechanism for the effect of intracellular Ca^2+ on synaptic release has not yet been understood. In this research, 1,2-bis-(o-aminophenoxy)-ethane-N, N, N′, N′-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM) was used to combine with cytosolic free Ca^2+ in a calcium free medium of cultured Xenopus neuromuscular junctions (NMJ), The spontaneous synaptic current (SSC) frequency was obviously reduced. Then, drugs were applied to interrupt and activate the Ca2+ release channels in the endoplasmic reticulum (ER) membrane, but the SSC frequency was not affected. The results show that spontaneous neurotransmitter release depends on intracellular rather than ER calcium in cultured Xenopus NMJ without extracellular calcium.
基金National Institute of Dental&Craniofacial Research,No.1R21DE028265-01A1.
文摘Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryonic stem cells),multipotent(hematopoietic stem cells,multipotent adult progenitor stem cells,and mesenchymal stem cells[MSCs]),and unipotent(progenitor cells that differentiate into a single lineage)cells.Though bone marrow is the primary source of multipotent stem cells in adults,other tissues such as adipose tissues,placenta,amniotic fluid,umbilical cord blood,periodontal ligament,and dental pulp also harbor stem cells that can be used for regenerative therapy.In addition,induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells,and thus could be another source for regenerative medicine.Several diseases including neurodegenerative diseases,cardiovascular diseases,autoimmune diseases,virus infection(also coronavirus disease 2019)have limited success with conventional medicine,and stem cell transplantation is assumed to be the best therapy to treat these disorders.Importantly,MSCs,are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair.Moreover,MSCs have the potential to migrate towards the damaged area,which is regulated by various factors and signaling processes.Recent studies have shown that extracellular calcium(Ca^(2+))promotes the proliferation of MSCs,and thus can assist in transplantation therapy.Ca^(2+)signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors,Ca^(2+)channels/pumps/exchangers,Ca^(2+)buffers,and Ca^(2+)sensors,which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity,which will be discussed in this review.
基金Supported by the National Natural Science Foundation of China (No. 30370468)
文摘Spontaneous secretions occur in both neurons and non-neuronal cells, and calcium is important for these secretion processes. However, the detailed roles of calcium on the secretions have not yet been identified. In the present study, cultured Xenopus myocytes loaded with exogenous acetylcholine (ACh) into the cytoplasm in the absence of extracellular Ca^2+ undergo spontaneous quantal ACh secretion as detected by the appearance of pulsatile miniature endplate currents. Analysis of the frequencies, amplitudes, and time courses of these currents suggests that similar cellular mechanisms are involved in the secretions of ACh in normal medium and Ca^2+-free solution. Various doses of ryanodine were used to regulate the intra- cellular Ca^2+ to different levels. The spontaneous ACh secretion from myocytes in Ca^2+-free medium was decreased by reducing intracellular Ca^2+ levels and enhanced by increasing cytosolic Ca^2+ levels. These observations demonstrate that the spontaneous secretion from isolated myocytes and the effect of ryanodine on ACh-loaded cells are both independent of extracellular Ca^2+ while Ca^2+ in the sarcoplasmic reticulum plays a crucial role in the secretions.