BACKGROUND： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules relate...BACKGROUND： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules related to Rho GTPases. OBJECTIVE： To investigate messenger ribonucleic acid mRNA expression of signaling molecules associated with Rho GTPases, including Rho-A, Rac-1, collapsin response mediator protein 1 （CRMP-1）, and tubulin 133 （Tub/33） during rat hippocampus development. DESIGN, TIME AND SETTING- A non-randomized, controlled, animal experiment, based on different developmental stages of the rat hippocampus, was performed at the Guangdong Key Laboratory of Tissue Construction and Detection, Institute of Clinical Anatomy, Southern Medical University between December 2005 and July 2007. MATERIALS： Trizol reagent was purchased from Invitrogen, USA. RNA PCR kit （AMV） Ver 3.0 and 150 bp DNA Ladder Marker were purchased from TaKaRa, Japan. Unless otherwise specified, all other reagents were purchased from Sigma-Aldrich, USA. METHODS： Twenty-five Sprague Dawley rats were assigned to five groups （n = 5） according to developmental stages： embryonic （embryonic 15 days）, neonatal （postnatal 5 days）, juvenile （postnatal 1 month）, adult （postnatal 3 months）, and senile （postnatal 18 months）. MAIN OUTCOME MEASURES： Detection of mRNA expression of Rho-A, Rac-1, CRMP-1, and Tub β3 during various hippocampal developmental stages by reverse-transcription polymerase chain reaction. RESULTS： Hippocampal mRNA expression of Rho-A, as well as Rac-1, reached peak levels at embryonic, juvenile, and senile stages, and was relatively less during neonatal and adult stages. mRNA expression of Rac-1 was greater than Rho-A during each hippocampal developmental stage. CRMP-1 mRNA expression levels were as follows： embryonic 〉 neonatal 〉 juvenile 〉 adult 〈 senile, while Tubβ3 mRNA expression was embryonic 〉 neonatal 〉 juvenile 〉 adult = senile. CONCLUSION： Rho-A and Rac-1 shared similar expression profiles, which demonstrated similar variations during the entire rat hippocampus developmental process. However, Rac-1 mRNA expression remained greater than Rho-A. Both CRMP-1 and Tubβ3 mRNA expression profiles gradually declined during hippocampal development from embryonic to adult stages. Tubβ3 mRNA expression arrested during the adult stage, and CRMP-1 mRNA expression increased during the senile stage.展开更多
Aim:Extinction of aversive memories associated with drug withdrawal has been proposed as a therapeutic strategy for the treatment of drug addiction.However,the mechanisms underlying extinction of such memory are poorl...Aim:Extinction of aversive memories associated with drug withdrawal has been proposed as a therapeutic strategy for the treatment of drug addiction.However,the mechanisms underlying extinction of such memory are poorly understood.This study was,therefore,undertaken to investigate the role of Rho GTPase Rac1-mediated GABAAR endocytosis in the vmPFC in extinction of aversive memories associated with drug withdrawal.Methods:conditioned place aversion(CPA)was used as a model for measurement of the aversive memories of opiate withdrawal.Extinction experiments were performed as described in our previous study(Wang et al.,2012).Results:we found that extinction of CPA required activation of Rac1 in the vmPFC in a brain-derived neurotrophic factor(BDNF)-dependent manner,which triggers actin polymerization via Pak1-cofilin signaling pathway,leading to synaptic localization of activity-regulated cytoskeleton-associated protein(Arc)in the vmPFC.The synaptic Arc further determines GABAA receptor(GABAAR)endocytosis that is necessary and sufficient for vmPFC long-term potentiation and CPA extinction.Thus,extinction of an aversive memory associated with drug withdrawal is intriguingly controlled by Rac1-dependent GABAAR endocytosis in the vmPFC,thereby suggesting therapeutic targets to promote extinction of the unwanted memory.Conclusion:BDNF dependent Rac1 GTPase activation in the vmPFC contributes to aversive memory extinction by Arc-mediated GABAA receptor endocytosis.展开更多
Enterovirus A71(EV-A71)is one of the main causative agents of hand,foot and mouth disease(HFMD)and it also causes severe neurologic complications in infected children.The interactions between some viruses and the host...Enterovirus A71(EV-A71)is one of the main causative agents of hand,foot and mouth disease(HFMD)and it also causes severe neurologic complications in infected children.The interactions between some viruses and the host mitochondria are crucial for virus replication and pathogenicity.In this study,it was observed that EV-A71 infection resulted in a perinuclear redistribution of the mitochondria.The mitochondria rearrangement was found to require the microtubule network,the dynein complex and a low cytosolic calcium concentration.Subsequently,the EV-A71 non-structural protein 2BC was identified as the viral protein capable of inducing mitochondria clustering.The protein was found localized on mitochondria and interacted with the mitochondrial Rho GTPase 1(RHOT1)that is a key protein required for attachment between the mitochondria and the motor proteins,which are responsible for the control of mitochondria movement.Additionally,suppressing mitochondria clustering by treating cells with nocodazole,EHNA,thapsigargin or A23187 consistently inhibited EV?A71 replication,indicating that mitochondria recruitment played a crucial role in the EV-A71 life cycle.This study identified a novel function of the EV-A71 2BC protein and provided a potential model for the regulation of mitochondrial motility in EV-A71 infection.展开更多
Cytokinesis is the last step of the M （mitosis） phase, yet it is crucial for the faithful division of one cell into two. Cytokinesis failure is often associated with cancer. Cytoldnesis can be morphologically divide...Cytokinesis is the last step of the M （mitosis） phase, yet it is crucial for the faithful division of one cell into two. Cytokinesis failure is often associated with cancer. Cytoldnesis can be morphologically divided into four steps： cleavage furrow initiation, cleavage furrow ingression, midbody formation and abscission. Molecular studies have revealed that RhoA as well as its regulators and effectors are im- portant players to ensure a successful cytokinesis. At the same time, Polo-like kinase 1 （Plkl） is an important kinase that can target many substrates and carry out different functions during mitosis, including cytokinesis. Recent studies are beginning to unveil a closer tie be- tween Plkl and RhoA networks. More specifically, Plkl phosphorylates the centralspindlin complex Cyk4 and MKLPI/CHO1, thus re- cruiting RhoA guanine nucleotide-exchange factor （GEF） Ect2 through its phosphopeptide-binding BRCT domains. Ect2 itself can be phosphorylated by Plkl in vitro. Plkl can also phosphorylate another GEF MyoGEF to regulate RhoA activity. Once activated, RhoA-GTP will activate downstream effectors, including ROCK1 and ROCK2. ROCK2 is among the proteins that associate with Plkl Polo-binding domain （PBD） in a large proteomic screen, and Plkl can phosphorylate ROCK2 in vitro. We review current understandings of the interplay between Plkl, RhoA proteins and other proteins （e.g., NudC, MKLP2, PRC 1, CEP55） involved in cytokinesis, with particular emphasis of its clinical implications in cancer.展开更多
The member of Rho family of small GTPases Cdc42 plays important and conserved roles in cell polarity and motility. The Cdc42ep family proteins have been identified to bind to Cdc42, yet how they interact with Cdc42 to...The member of Rho family of small GTPases Cdc42 plays important and conserved roles in cell polarity and motility. The Cdc42ep family proteins have been identified to bind to Cdc42, yet how they interact with Cdc42 to regulate cell migration remains to be elucidated. In this study, we focus on Cdc42epl, which is expressed predominantly in the highly migratory neural crest ceils in frog embryos. Through morpholino-mediated knockdown, we show that Cdc42epl is required for the migration of cranial neural crest cells. Loss of Cdc42epl leads to rounder cell shapes and the formation of membrane blebs, consistent with the observed disruption in actin organization and focal adhesion alignment. As a result, Cdc42ep1 is critical for neural crest cells to apply traction forces at the correct place to migrate efficiently. We further show that Cdc42ep1 is localized to two areas in neural crest celts： in membrane protrusions together with Cdc42 and in perinuciear patches where Cdc42 is absent. Cdc42 directly interacts with Cdc42epl （through the CRIB domain） and changes in Cdc42 level shift the distribution of Cdc42epl between these two subcellular locations, controlling the formation of membrane protrusions and directionality of migration as a consequence. These results suggest that Cdc42ep1 elaborates Cdc42 activity in neural crest cells to promote their efficient migration.展开更多
基金Supported by:the National Basic Research Program of China(973 Program),No. 2007CB512705the Natural Science Foundation of Guangdong Province,No. 8451063201000193
文摘BACKGROUND： Rho GTPase family members have been shown to participate in neurite growth by regulating the neuronal cytoskeleton. However, there are very few reports of developmental roles of signaling molecules related to Rho GTPases. OBJECTIVE： To investigate messenger ribonucleic acid mRNA expression of signaling molecules associated with Rho GTPases, including Rho-A, Rac-1, collapsin response mediator protein 1 （CRMP-1）, and tubulin 133 （Tub/33） during rat hippocampus development. DESIGN, TIME AND SETTING- A non-randomized, controlled, animal experiment, based on different developmental stages of the rat hippocampus, was performed at the Guangdong Key Laboratory of Tissue Construction and Detection, Institute of Clinical Anatomy, Southern Medical University between December 2005 and July 2007. MATERIALS： Trizol reagent was purchased from Invitrogen, USA. RNA PCR kit （AMV） Ver 3.0 and 150 bp DNA Ladder Marker were purchased from TaKaRa, Japan. Unless otherwise specified, all other reagents were purchased from Sigma-Aldrich, USA. METHODS： Twenty-five Sprague Dawley rats were assigned to five groups （n = 5） according to developmental stages： embryonic （embryonic 15 days）, neonatal （postnatal 5 days）, juvenile （postnatal 1 month）, adult （postnatal 3 months）, and senile （postnatal 18 months）. MAIN OUTCOME MEASURES： Detection of mRNA expression of Rho-A, Rac-1, CRMP-1, and Tub β3 during various hippocampal developmental stages by reverse-transcription polymerase chain reaction. RESULTS： Hippocampal mRNA expression of Rho-A, as well as Rac-1, reached peak levels at embryonic, juvenile, and senile stages, and was relatively less during neonatal and adult stages. mRNA expression of Rac-1 was greater than Rho-A during each hippocampal developmental stage. CRMP-1 mRNA expression levels were as follows： embryonic 〉 neonatal 〉 juvenile 〉 adult 〈 senile, while Tubβ3 mRNA expression was embryonic 〉 neonatal 〉 juvenile 〉 adult = senile. CONCLUSION： Rho-A and Rac-1 shared similar expression profiles, which demonstrated similar variations during the entire rat hippocampus developmental process. However, Rac-1 mRNA expression remained greater than Rho-A. Both CRMP-1 and Tubβ3 mRNA expression profiles gradually declined during hippocampal development from embryonic to adult stages. Tubβ3 mRNA expression arrested during the adult stage, and CRMP-1 mRNA expression increased during the senile stage.
文摘Aim:Extinction of aversive memories associated with drug withdrawal has been proposed as a therapeutic strategy for the treatment of drug addiction.However,the mechanisms underlying extinction of such memory are poorly understood.This study was,therefore,undertaken to investigate the role of Rho GTPase Rac1-mediated GABAAR endocytosis in the vmPFC in extinction of aversive memories associated with drug withdrawal.Methods:conditioned place aversion(CPA)was used as a model for measurement of the aversive memories of opiate withdrawal.Extinction experiments were performed as described in our previous study(Wang et al.,2012).Results:we found that extinction of CPA required activation of Rac1 in the vmPFC in a brain-derived neurotrophic factor(BDNF)-dependent manner,which triggers actin polymerization via Pak1-cofilin signaling pathway,leading to synaptic localization of activity-regulated cytoskeleton-associated protein(Arc)in the vmPFC.The synaptic Arc further determines GABAA receptor(GABAAR)endocytosis that is necessary and sufficient for vmPFC long-term potentiation and CPA extinction.Thus,extinction of an aversive memory associated with drug withdrawal is intriguingly controlled by Rac1-dependent GABAAR endocytosis in the vmPFC,thereby suggesting therapeutic targets to promote extinction of the unwanted memory.Conclusion:BDNF dependent Rac1 GTPase activation in the vmPFC contributes to aversive memory extinction by Arc-mediated GABAA receptor endocytosis.
基金supported by grants from the National Natural Science Foundation of China (NSFC) (Grants Nos. 81621091, 31370201)
文摘Enterovirus A71(EV-A71)is one of the main causative agents of hand,foot and mouth disease(HFMD)and it also causes severe neurologic complications in infected children.The interactions between some viruses and the host mitochondria are crucial for virus replication and pathogenicity.In this study,it was observed that EV-A71 infection resulted in a perinuclear redistribution of the mitochondria.The mitochondria rearrangement was found to require the microtubule network,the dynein complex and a low cytosolic calcium concentration.Subsequently,the EV-A71 non-structural protein 2BC was identified as the viral protein capable of inducing mitochondria clustering.The protein was found localized on mitochondria and interacted with the mitochondrial Rho GTPase 1(RHOT1)that is a key protein required for attachment between the mitochondria and the motor proteins,which are responsible for the control of mitochondria movement.Additionally,suppressing mitochondria clustering by treating cells with nocodazole,EHNA,thapsigargin or A23187 consistently inhibited EV?A71 replication,indicating that mitochondria recruitment played a crucial role in the EV-A71 life cycle.This study identified a novel function of the EV-A71 2BC protein and provided a potential model for the regulation of mitochondrial motility in EV-A71 infection.
基金supported by the National Natural Science Foundation of China (NSFC) (No.30700420)Beijing Nova Program (No.2007B062)+5 种基金Scientific Research Program of Beijing Municipal Commission of Education (No.KM200810028013)Scientific Research Foundation for the Returned Overseas Chinese Scholars from Beijing Municipal Commission of Human Resources (No.085402600)from State Education Ministry (SRF for ROCS,SEM) to J.L.X.X.was supported by the startup fund from CNU,NSFC funds (No.30570371,90608014,and 30711120570)the Program for New Century Excellent Talents in University (No.NCET-06-0187)Beijing Natural Science Foundation Program and Scientific Research Key Program of Beijing Municipal Commission of Education (No.KZ200810028014)Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (PHR(IHLB))
文摘Cytokinesis is the last step of the M （mitosis） phase, yet it is crucial for the faithful division of one cell into two. Cytokinesis failure is often associated with cancer. Cytoldnesis can be morphologically divided into four steps： cleavage furrow initiation, cleavage furrow ingression, midbody formation and abscission. Molecular studies have revealed that RhoA as well as its regulators and effectors are im- portant players to ensure a successful cytokinesis. At the same time, Polo-like kinase 1 （Plkl） is an important kinase that can target many substrates and carry out different functions during mitosis, including cytokinesis. Recent studies are beginning to unveil a closer tie be- tween Plkl and RhoA networks. More specifically, Plkl phosphorylates the centralspindlin complex Cyk4 and MKLPI/CHO1, thus re- cruiting RhoA guanine nucleotide-exchange factor （GEF） Ect2 through its phosphopeptide-binding BRCT domains. Ect2 itself can be phosphorylated by Plkl in vitro. Plkl can also phosphorylate another GEF MyoGEF to regulate RhoA activity. Once activated, RhoA-GTP will activate downstream effectors, including ROCK1 and ROCK2. ROCK2 is among the proteins that associate with Plkl Polo-binding domain （PBD） in a large proteomic screen, and Plkl can phosphorylate ROCK2 in vitro. We review current understandings of the interplay between Plkl, RhoA proteins and other proteins （e.g., NudC, MKLP2, PRC 1, CEP55） involved in cytokinesis, with particular emphasis of its clinical implications in cancer.
基金This work is supported by the National Institutes of Health （ROODE022796 to S.N.） and National Science Foundation （DMR- 0955811 to J.E.C. and PHY-0848797 to J.E.C. and D.T.K.）.
文摘The member of Rho family of small GTPases Cdc42 plays important and conserved roles in cell polarity and motility. The Cdc42ep family proteins have been identified to bind to Cdc42, yet how they interact with Cdc42 to regulate cell migration remains to be elucidated. In this study, we focus on Cdc42epl, which is expressed predominantly in the highly migratory neural crest ceils in frog embryos. Through morpholino-mediated knockdown, we show that Cdc42epl is required for the migration of cranial neural crest cells. Loss of Cdc42epl leads to rounder cell shapes and the formation of membrane blebs, consistent with the observed disruption in actin organization and focal adhesion alignment. As a result, Cdc42ep1 is critical for neural crest cells to apply traction forces at the correct place to migrate efficiently. We further show that Cdc42ep1 is localized to two areas in neural crest celts： in membrane protrusions together with Cdc42 and in perinuciear patches where Cdc42 is absent. Cdc42 directly interacts with Cdc42epl （through the CRIB domain） and changes in Cdc42 level shift the distribution of Cdc42epl between these two subcellular locations, controlling the formation of membrane protrusions and directionality of migration as a consequence. These results suggest that Cdc42ep1 elaborates Cdc42 activity in neural crest cells to promote their efficient migration.
