Estudio proteómico de factores moleculares que coordinan la reprogramación génica estacional del pez Cyprinus carpio
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2010
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es
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Universidad Andrés Bello
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Licencia CC
Resumen
RESUMEN: El pez Cyprinus carpio es un ectotermo euritermal que habita los ríos de la zona central y
sur de Chile. En este escenario, se ve enfrentado a las variaciones físicas del medio
ambiente propias de un clima con las estaciones claramente diferenciadas. El fenómeno de
plasticidad fenotípica concomitante a las variaciones estacionales se conoce como
aclimatización, el cual se ve reflejado a nivel fisiológico, celular y molecular. En la carpa,
el cambio más notable se observa en el reordenamiento ultraestructural que sufre el
nucléolo, el cual durante la estación veraniega presenta sus componentes integrados (con
una alta actividad transcripcional), mientras que en invierno sus componentes se observan
segregados (representativo de una baja tasa transcripcional). Nuestra hipótesis de trabajo
sostiene que la homeostasis que caracteriza la adaptación estacional de la carpa, implica
cambios en el repertorio de proteínas nucleares y en él se representan los factores
moleculares centrales para la coordinación de la reprogramación génica estacional de C.
carpio. Este estudio, permitió demostrar los cambios que sufre el proteoma nuclear de la
carpa concomitante a la adaptación estacional, observándose que aproximadamente un 10%
de las proteínas presentes en ambas estaciones son reguladas. Adicionalmente, hemos
identificado cinco proteínas, dos no mostraron variación estacional y tres se sobre
expresaron durante el invierno. Las identidades de estas proteínas nos sugieren la
participación de diversos mecanismos regulatorios de la expresión génica en el proceso de
aclimatización. La subunidad Rpb7 es necesaria para el inicio de transcripción y Spt4
participa de la elongación de la transcripción, Pur b se ha descrito como represor de ciertos
genes en células musculares, mientras que CENP-A y Actina1 muestran funciones
asociadas la estructura de la cromatina. Paralelamente, hemos evidenciado que la histona
variante H2A.Z presenta una regulación estacional durante el proceso adaptativo. En
particular, esta variante de histona se encuentra enriquecida en los genes ribosomales de la
carpa (principalmente en verano), y su relación a través de ensayo de reChIp con
marcadores epigenéticos de activación (AcK12H4) y represión (DimetK27H3), nos sugiere
su participación en la modulación de la actividad transcripcional de los genes ribosomales
durante el fenómeno de aclimatización. Las funciones descritas para estas proteínas, nos
sugieren que la regulación de la expresión génica se llevaría a cabo a través de factores
XII
transcripcionales específicos y de la modulación de la estructura de la cromatina. Esto nos
indica la concertación de diversos procesos nucleares, los cuales sustentarían la
reprogramación génica cíclica como una de las respuestas compensatorias centrales frente a
los cambios medioambientales al que debe hacer frente el pez C. carpio.
ABSTRACT: The ectotherm eurithermal fish Cyprinus carpio lives in the rivers of the central and south areas of Chile. It faces clearly differentiated seasons and it is subjected to selective pressure impose by environmental fluctuations. The carp adaptative response to this phenomenon is a complex mechanism that involves physiological, cellular and molecular adjustments. The phenotypic plasticity of the carp concomitant to seasonal variations is known as acclimatization. This process involves profound nucleolar adjustments and remarkable changes in RNA synthesis, which affects ribosomal biosynthesis. The hypothesis proposes that the homeostasis which characterizes the seasonal adaptation of the C. carpio in winter and summer, involves changes in the repertory of nuclear proteins and those changes include the central molecular factors for coordinating the seasonal gene reprogramming in C. carpio. This study has demonstrated the changes experienced by the nuclear proteome concomitant upon seasonal acclimatization. It has been observed that 10% of the proteins present in both seasons are regulated. In addition, this work identified five proteins; two without seasonal changes y three were overexpressed during the winter. The identities of these proteins suggest the involvement of various mechanisms of gene expression in the process of acclimatization. Rpb7 is required for the initiation of transcription; Purb has been described as a repressor of certain genes in muscle cells, while CENP-A and Actina1-A shows the functions associated to the chromatin’s structure. Parallel to this, it was shown that H2A.Z presents a seasonal regulation during the adaptative process. This histone variant was demonstrated to be associated with ribosomal genes, mainly in summer. Also, its relationship, tested by reChIp, with activation (AcK12H4) and repression (DimetK27H3) epigenetic markers suggests its involvement in the modulation of ribosomal genes transcription during seasonal acclimatization. The functions of these proteins suggest that gene expression regulation would be carrying out through specific transcriptional factors and changes in chromatin structure. This indicate the diverse nuclear processes coordination, which support the cyclical gene reprogramming as a compensatory response to changes in the physical environment that affects fish C. carpio.
ABSTRACT: The ectotherm eurithermal fish Cyprinus carpio lives in the rivers of the central and south areas of Chile. It faces clearly differentiated seasons and it is subjected to selective pressure impose by environmental fluctuations. The carp adaptative response to this phenomenon is a complex mechanism that involves physiological, cellular and molecular adjustments. The phenotypic plasticity of the carp concomitant to seasonal variations is known as acclimatization. This process involves profound nucleolar adjustments and remarkable changes in RNA synthesis, which affects ribosomal biosynthesis. The hypothesis proposes that the homeostasis which characterizes the seasonal adaptation of the C. carpio in winter and summer, involves changes in the repertory of nuclear proteins and those changes include the central molecular factors for coordinating the seasonal gene reprogramming in C. carpio. This study has demonstrated the changes experienced by the nuclear proteome concomitant upon seasonal acclimatization. It has been observed that 10% of the proteins present in both seasons are regulated. In addition, this work identified five proteins; two without seasonal changes y three were overexpressed during the winter. The identities of these proteins suggest the involvement of various mechanisms of gene expression in the process of acclimatization. Rpb7 is required for the initiation of transcription; Purb has been described as a repressor of certain genes in muscle cells, while CENP-A and Actina1-A shows the functions associated to the chromatin’s structure. Parallel to this, it was shown that H2A.Z presents a seasonal regulation during the adaptative process. This histone variant was demonstrated to be associated with ribosomal genes, mainly in summer. Also, its relationship, tested by reChIp, with activation (AcK12H4) and repression (DimetK27H3) epigenetic markers suggests its involvement in the modulation of ribosomal genes transcription during seasonal acclimatization. The functions of these proteins suggest that gene expression regulation would be carrying out through specific transcriptional factors and changes in chromatin structure. This indicate the diverse nuclear processes coordination, which support the cyclical gene reprogramming as a compensatory response to changes in the physical environment that affects fish C. carpio.
Notas
Tesis (Doctor en Biociencias Moleculares)
Palabras clave
Pez Carpa -- Genética.