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1.
Proc Natl Acad Sci U S A ; 116(27): 13651-13660, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31209021

RESUMO

Adult hippocampal neurogenesis involves the lifelong generation of neurons. The process depends on the homeostasis of the production of neurons and maintenance of the adult neural stem cell (NSC) pool. Here, we report that α2-chimaerin, a Rho GTPase-activating protein, is essential for NSC homeostasis in adult hippocampal neurogenesis. Conditional deletion of α2-chimaerin in adult NSCs resulted in the premature differentiation of NSCs into intermediate progenitor cells (IPCs), which ultimately depleted the NSC pool and impaired neuron generation. Single-cell RNA sequencing and pseudotime analyses revealed that α2-chimaerin-conditional knockout (α2-CKO) mice lacked a unique NSC subpopulation, termed Klotho-expressing NSCs, during the transition of NSCs to IPCs. Furthermore, α2-CKO led to defects in hippocampal synaptic plasticity and anxiety/depression-like behaviors in mice. Our findings collectively demonstrate that α2-chimaerin plays an essential role in adult hippocampal NSC homeostasis to maintain proper brain function.


Assuntos
Proteínas Quimerinas/fisiologia , Ativadores de GTP Fosfo-Hidrolase/metabolismo , Células-Tronco Neurais/metabolismo , Neurogênese/fisiologia , Animais , Diferenciação Celular , Técnicas de Silenciamento de Genes , Hipocampo/fisiologia , Homeostase , Camundongos , Camundongos Knockout , Células-Tronco Neurais/fisiologia , Células-Tronco/fisiologia
2.
Biochem J ; 403(1): 1-12, 2007 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-17346241

RESUMO

Chimaerins are the only known RhoGAPs (Rho GTPase-activating proteins) that bind phorbol ester tumour promoters and the lipid second messenger DAG (diacylglycerol), and show specific GAP activity towards the small GTPase Rac. This review summarizes our knowledge of the structure, biochemical and biological properties of chimaerins. Recent findings have established that chimaerins are regulated by tyrosine kinase and GPCRs (G-protein-coupled receptors) via PLC (phospholipase C) activation and DAG generation to promote Rac inactivation. The finding that chimaerins, along with some other proteins, are receptors for DAG changed the prevalent view that PKC (protein kinase C) isoenzymes are the only cellular molecules regulated by DAG. In addition, vigorous recent studies have begun to decipher the critical roles of chimaerins in the central nervous system, development and tumour progression.


Assuntos
Proteínas Quimerinas/fisiologia , Diglicerídeos/fisiologia , Proteínas rac de Ligação ao GTP/fisiologia , Animais , Divisão Celular , Neoplasias Mamárias Experimentais/patologia , Neoplasias Mamárias Experimentais/fisiopatologia , Morfogênese , Neurônios/fisiologia , Transdução de Sinais
3.
Proc Natl Acad Sci U S A ; 103(14): 5373-8, 2006 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-16569702

RESUMO

In this paper, we report an in vivo model for the chimerins, a family of Rac GTPase-activating proteins (Rac-GAPs) that are uniquely regulated by the lipid second messenger diacylglycerol and have been implicated in the control of actin dynamics, migration, and proliferation. We cloned the zebrafish homologue of mammalian alpha2-chimerin (chn1) and determined that it possesses Rac-GAP activity and a C1 domain with phorbol ester/diacylglycerol-binding capability. chn1 morpholino knockdown embryos exhibit severe abnormalities, including the development of round somites, lack of yolk extension, and a kinked posterior notochord. These zebrafish morphants show Rac hyperactivation and progress faster through epiboly, leading to tailbud-stage embryos that have a narrow axis and an enlarged tailbud with expanded bmp4 and shh expression. Phenotypic rescue was achieved by mRNA microinjection of chn1 or an active chimerin Rac-GAP domain into the yolk syncytial layer but not by a chn1 mutant deficient in Rac-GAP activity, suggesting that the lack of chn1 Rac-GAP activity in the yolk syncytial layer was causative of the misbalance in morphogenetic movements. Our results reveal a crucial role for chn1 in early development and implicate Rac as a key regulator of morphogenetic movements during zebrafish epiboly.


Assuntos
Divisão Celular , Proteínas Quimerinas/química , Proteínas Quimerinas/fisiologia , Animais , Sequência de Bases , Células COS , Proteínas Quimerinas/genética , Chlorocebus aethiops , Clonagem Molecular , Primers do DNA , Hibridização In Situ , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Peixe-Zebra/embriologia
4.
Cancer Res ; 61(24): 8629-37, 2001 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-11751375

RESUMO

Vascular endothelial growth factor (VEGF) is a dimeric angiogenic factor that is overexpressed by many tumors and stimulates tumor angiogenesis. VEGF initiates signaling by dimerizing the receptors VEGFR-1 and VEGFR-2. The Fas receptor stimulates apoptosis, and artificial dimerization of the Fas cytoplasmic domain has been shown to induce apoptosis. We constructed a chimeric receptor (VEGFR2Fas) combining the extracellular and transmembrane domains of VEGFR-2 with the cytoplasmic domain of Fas receptor. When VEGFR2Fas was stably expressed in endothelial cells in vitro, treatment with VEGF rapidly induced cell death with features characteristic of Fas-mediated apoptosis. These findings demonstrate that VEGFR2Fas functions as a VEGF-triggered death receptor and raise the possibility that introduction of VEGFR2Fas into tumor endothelium or tumor cells in vivo may convert tumor-derived VEGF from an angiogenic factor into an antiangiogenesis agent.


Assuntos
Apoptose/fisiologia , Fatores de Crescimento Endotelial/farmacologia , Endotélio Vascular/citologia , Linfocinas/farmacologia , Receptores Proteína Tirosina Quinases/fisiologia , Receptores de Fatores de Crescimento/fisiologia , Receptor fas/fisiologia , Animais , Aorta/citologia , Apoptose/efeitos dos fármacos , Linhagem Celular , Proteínas Quimerinas/genética , Proteínas Quimerinas/metabolismo , Proteínas Quimerinas/fisiologia , DNA Complementar/genética , Dimerização , Fatores de Crescimento Endotelial/metabolismo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Humanos , Linfocinas/metabolismo , Estrutura Terciária de Proteína , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Receptores de Fatores de Crescimento/genética , Receptores de Fatores de Crescimento/metabolismo , Receptores de Fatores de Crescimento do Endotélio Vascular , Suínos , Transfecção , Fator A de Crescimento do Endotélio Vascular , Fatores de Crescimento do Endotélio Vascular , Receptor fas/genética , Receptor fas/metabolismo
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