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1.
J Cell Sci ; 131(8)2018 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-29588396

RESUMEN

Abscission is the final step of cytokinesis whereby the intercellular bridge (ICB) linking the two daughter cells is cut. The ICB contains a structure called the midbody, required for the recruitment and organization of the abscission machinery. Final midbody severing is mediated by formation of secondary midbody ingression sites, where the ESCRT III component CHMP4B is recruited to mediate membrane fusion. It is presently unknown how cytoskeletal elements cooperate with CHMP4B to mediate abscission. Here, we show that F-actin is associated with midbody secondary sites and is necessary for abscission. F-actin localization at secondary sites depends on the activity of RhoA and on the abscission regulator citron kinase (CITK). CITK depletion accelerates loss of F-actin proteins at the midbody and subsequent cytokinesis defects are reversed by restoring actin polymerization. Conversely, midbody hyperstabilization produced by overexpression of CITK and ANLN is reversed by actin depolymerization. CITK is required for localization of F-actin and ANLN at the abscission sites, as well as for CHMP4B recruitment. These results indicate that control of actin dynamics downstream of CITK prepares the abscission site for the final cut.


Asunto(s)
Actinas/metabolismo , Citocinesis/fisiología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Humanos
2.
Cell Mol Life Sci ; 75(21): 3963-3976, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30116853

RESUMEN

Maintenance of genome stability is a crucial cellular function for normal mammalian development and physiology. However, despite the general relevance of this process, genome stability alteration due to genetic or non-genetic conditions has a particularly profound impact on the developing cerebral cortex. In this review, we will analyze the main pathways involved in maintenance of genome stability, the consequences of their alterations with regard to central nervous system development, as well as the possible molecular and cellular basis of this specificity.


Asunto(s)
Daño del ADN/genética , Reparación del ADN/genética , Anemia de Fanconi/genética , Inestabilidad Genómica/genética , Anemia de Fanconi/patología , Humanos , Neurogénesis/genética
3.
EMBO Rep ; 17(10): 1396-1409, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27562601

RESUMEN

Correct orientation of cell division is considered an important factor for the achievement of normal brain size, as mutations in genes that affect this process are among the leading causes of microcephaly. Abnormal spindle orientation is associated with reduction of the neuronal progenitor symmetric divisions, premature cell cycle exit, and reduced neurogenesis. This mechanism has been involved in microcephaly resulting from mutation of ASPM, the most frequently affected gene in autosomal recessive human primary microcephaly (MCPH), but it is presently unknown how ASPM regulates spindle orientation. In this report, we show that ASPM may control spindle positioning by interacting with citron kinase (CITK), a protein whose loss is also responsible for severe microcephaly in mammals. We show that the absence of CITK leads to abnormal spindle orientation in mammals and insects. In mouse cortical development, this phenotype correlates with increased production of basal progenitors. ASPM is required to recruit CITK at the spindle, and CITK overexpression rescues ASPM phenotype. ASPM and CITK affect the organization of astral microtubules (MT), and low doses of MT-stabilizing drug revert the spindle orientation phenotype produced by their knockdown. Finally, CITK regulates both astral-MT nucleation and stability. Our results provide a functional link between two established microcephaly proteins.


Asunto(s)
Proteínas de Unión a Calmodulina/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Microtúbulos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Huso Acromático/metabolismo , Animales , Encéfalo/metabolismo , Proteínas de Unión a Calmodulina/genética , Línea Celular , Drosophila , Complejo Dinactina/metabolismo , Femenino , Regulación de la Expresión Génica , Silenciador del Gen , Células HeLa , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Ratones , Ratones Noqueados , Mitosis/genética , Proteínas del Tejido Nervioso/genética , Unión Proteica , Proteínas Serina-Treonina Quinasas/genética , Estabilidad Proteica , Transporte de Proteínas , Interferencia de ARN
5.
J Med Genet ; 50(8): 543-51, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23749989

RESUMEN

BACKGROUND AND AIM: We identified a balanced de novo translocation involving chromosomes Xq25 and 8q24 in an eight year-old girl with a non-progressive form of congenital ataxia, cognitive impairment and cerebellar hypoplasia. METHODS AND RESULTS: Breakpoint definition showed that the promoter of the Protein Tyrosine Kinase 2 (PTK2, also known as Focal Adhesion Kinase, FAK) gene on chromosome 8q24.3 is translocated 2 kb upstream of the THO complex subunit 2 (THOC2) gene on chromosome Xq25. PTK2 is a well-known non-receptor tyrosine kinase whereas THOC2 encodes a component of the evolutionarily conserved multiprotein THO complex, involved in mRNA export from nucleus. The translocation generated a sterile fusion transcript under the control of the PTK2 promoter, affecting expression of both PTK2 and THOC2 genes. PTK2 is involved in cell adhesion and, in neurons, plays a role in axonal guidance, and neurite growth and attraction. However, PTK2 haploinsufficiency alone is unlikely to be associated with human disease. Therefore, we studied the role of THOC2 in the CNS using three models: 1) THOC2 ortholog knockout in C.elegans which produced functional defects in specific sensory neurons; 2) Thoc2 knockdown in primary rat hippocampal neurons which increased neurite extension; 3) Thoc2 knockdown in neuronal stem cells (LC1) which increased their in vitro growth rate without modifying apoptosis levels. CONCLUSION: We suggest that THOC2 can play specific roles in neuronal cells and, possibly in combination with PTK2 reduction, may affect normal neural network formation, leading to cognitive impairment and cerebellar congenital hypoplasia.


Asunto(s)
Cerebelo/anomalías , Cromosomas Humanos Par 8/genética , Quinasa 1 de Adhesión Focal/genética , Malformaciones del Sistema Nervioso/genética , Trastornos Psicomotores/genética , Proteínas de Unión al ARN/genética , Translocación Genética , Animales , Caenorhabditis elegans/genética , Línea Celular Transformada , Niño , Discapacidades del Desarrollo/complicaciones , Discapacidades del Desarrollo/genética , Femenino , Fusión Génica , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Malformaciones del Sistema Nervioso/complicaciones , Trastornos Psicomotores/complicaciones , Ratas
6.
Small GTPases ; 11(2): 122-130, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-29185861

RESUMEN

The Citron protein was originally identified for its capability to specifically bind the active form of RhoA small GTPase, leading to the simplistic hypothesis that it may work as a RhoA downstream effector in actin remodeling. More than two decades later, a much more complex picture has emerged. In particular, it has become clear that in animals, and especially in mammals, the functions of the Citron gene (CIT) are intimately linked to many aspects of central nervous system (CNS) development and function, although the gene is broadly expressed. More specifically, CIT encodes two main isoforms, Citron-kinase (CIT-K) and Citron-N (CIT-N), characterized by complementary expression pattern and different functions. Moreover, in many of their activities, CIT proteins act more as upstream regulators than as downstream effectors of RhoA. Finally it has been found that, besides working through actin, CIT proteins have many crucial functional interactions with the microtubule cytoskeleton and may directly affect genome stability. In this review, we will summarize these advances and illustrate their actual or potential relevance for CNS diseases, including microcephaly and psychiatric disorders.


Asunto(s)
Péptidos y Proteínas de Señalización Intracelular/metabolismo , Sistema Nervioso/crecimiento & desarrollo , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Regulación Enzimológica de la Expresión Génica , Variación Genética , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Sistema Nervioso/citología , Neuronas/citología , Fenotipo , Proteínas Serina-Treonina Quinasas/genética
7.
Cancer Res ; 78(16): 4599-4612, 2018 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-29921697

RESUMEN

Medulloblastoma is the most common malignant brain tumor in children. Current treatment for medulloblastoma consists of surgery followed by irradiation of the whole neuraxis and high-dose multiagent chemotherapy, a partially effective strategy associated with highly invalidating side effects. Therefore, identification and validation of novel target molecules capable of contrasting medulloblastoma growth without disturbing brain development is needed. Citron kinase protein (CITK), encoded by primary microcephaly gene MCPH17, is required for normal proliferation and survival of neural progenitors. Constitutive loss of CITK leads to cytokinesis failure, chromosome instability, and apoptosis in the developing brain, but has limited effects on other tissues. On this basis, we hypothesized that CITK could be an effective target for medulloblastoma treatment. In medulloblastoma cell lines DAOY and ONS-76, CITK knockdown increased both cytokinesis failure and DNA damage, impairing proliferation and inducing cell senescence and apoptosis via TP53 or TP73. Similar effects were obtained in the NeuroD-SmoA1 transgenic mouse model, in which CITK deletion increased apoptotic cells and senescence markers such as P21CIP1, P27KIP1, and P16INK4A Most importantly, CITK deletion decreased tumor growth and increased overall survival in these mice, with no apparent side effects. These results suggest that CITK can be a useful molecular target for medulloblastoma treatment.Significance:In vitro and in vivo proof of concept identifies citron kinase protein as a suitable target for medulloblastoma treatment.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/16/4599/F1.large.jpg Cancer Res; 78(16); 4599-612. ©2018 AACR.


Asunto(s)
Biomarcadores de Tumor/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Meduloblastoma/genética , Proteínas de Neoplasias/genética , Proteínas Serina-Treonina Quinasas/genética , Animales , Apoptosis/genética , Línea Celular Tumoral , Proliferación Celular/genética , Senescencia Celular/genética , Inestabilidad Cromosómica/genética , Citocinesis/genética , Daño del ADN/genética , Humanos , Meduloblastoma/patología , Ratones
8.
Cell Death Dis ; 9(12): 1155, 2018 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-30459303

RESUMEN

The authors wish to point out that the name of the first author is appearing incorrectly on Pubmed: it should be El Ghouzzi V (and not Ghouzzi VE). In addition, the words "and p53" appear at the end of the title in the original publication ( https://www.nature.com/articles/cddis2016266 ) and in the previous erratum version ( https://www.nature.com/articles/cddis2016446 ). This is not correct.

9.
Cell Death Dis ; 7(10): e2440, 2016 10 27.
Artículo en Inglés | MEDLINE | ID: mdl-27787521

RESUMEN

Epidemiological evidence from the current outbreak of Zika virus (ZIKV) and recent studies in animal models indicate a strong causal link between ZIKV and microcephaly. ZIKV infection induces cell-cycle arrest and apoptosis in proliferating neural progenitors. However, the mechanisms leading to these phenotypes are still largely obscure. In this report, we explored the possible similarities between transcriptional responses induced by ZIKV in human neural progenitors and those elicited by three different genetic mutations leading to severe forms of microcephaly in mice. We found that the strongest similarity between all these conditions is the activation of common P53 downstream genes. In agreement with these observations, we report that ZIKV infection increases total P53 levels and nuclear accumulation, as well as P53 Ser15 phosphorylation, correlated with genotoxic stress and apoptosis induction. Interestingly, increased P53 activation and apoptosis are induced not only in cells expressing high levels of viral antigens but also in cells showing low or undetectable levels of the same proteins. These results indicate that P53 activation is an early and specific event in ZIKV-infected cells, which could result from cell-autonomous and/or non-cell-autonomous mechanisms. Moreover, we highlight a small group of P53 effector proteins that could act as critical mediators, not only in ZIKV-induced microcephaly but also in many genetic microcephaly syndromes.


Asunto(s)
Daño del ADN/genética , Microcefalia/genética , Mutación/genética , Células-Madre Neurales/metabolismo , Células-Madre Neurales/virología , Proteína p53 Supresora de Tumor/metabolismo , Virus Zika/fisiología , Animales , Apoptosis/genética , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Humanos , Ratones , Proteína p53 Supresora de Tumor/genética , Regulación hacia Arriba/genética , Infección por el Virus Zika/genética , Infección por el Virus Zika/patología , Infección por el Virus Zika/virología
11.
PLoS One ; 6(7): e22370, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21829458

RESUMEN

Alzheimer disease (AD) is a neurodegenerative disorder characterized by progressive decline of cognitive function that represents one of the most dramatic medical challenges for the aging population. Aß peptides, generated by processing of the Amyloid Precursor Protein (APP), are thought to play a central role in the pathogenesis of AD. However, the network of physical and functional interactions that may affect their production and deposition is still poorly understood. The use of a bioinformatic approach based on human/mouse conserved coexpression allowed us to identify a group of genes that display an expression profile strongly correlated with APP. Among the most prominent candidates, we investigated whether the collagen chaperone HSP47 could be functionally correlated with APP. We found that HSP47 accumulates in amyloid deposits of two different mouse models and of some AD patients, is capable to physically interact with APP and can be relocalized by APP overexpression. Notably, we found that it is possible to reduce the levels of secreted Aß peptides by reducing the expression of HSP47 or by interfering with its activity via chemical inhibitors. Our data unveil HSP47 as a new functional interactor of APP and imply it as a potential target for preventing the formation and/or growth amyloid plaques.


Asunto(s)
Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Modelos Animales de Enfermedad , Proteínas del Choque Térmico HSP47/metabolismo , Placa Amiloide , Péptidos beta-Amiloides/genética , Precursor de Proteína beta-Amiloide/genética , Animales , Biomarcadores/metabolismo , Western Blotting , Encéfalo/metabolismo , Proliferación Celular , Células Cultivadas , Colágeno/metabolismo , Reactivos de Enlaces Cruzados/farmacología , Embrión de Mamíferos/citología , Embrión de Mamíferos/efectos de los fármacos , Embrión de Mamíferos/metabolismo , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente , Perfilación de la Expresión Génica , Proteínas del Choque Térmico HSP47/antagonistas & inhibidores , Proteínas del Choque Térmico HSP47/genética , Células HeLa , Hipocampo/citología , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Humanos , Técnicas para Inmunoenzimas , Inmunoprecipitación , Masculino , Ratones , Chaperonas Moleculares , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
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