ABSTRACT
La regeneración del corazón dañado ha sido objeto de intensa investigación durante la década pasada. Las diferentes estrategias que han sido desarrrolladas (como por ejemplo la terapia celular basada en células madre (ES)), esclarecen la información acerca de las moléculas y los factores de transcripción involucrados en las cardiomiogénesis. Sin embargo, todavía no es posible programar eficientemente las ES para que se desarrollen a cardiomiocitos. Los mecanismos celulares y moleculares inherentes en el desarrollo embrionario del corazón, así como las interconexiones entre ellos, pueden aportar datos acerca de las rutas bioquímicas necesarias para la diferenciación de las ES embrionarias a células cardíacas. Nosotros proponemos que un modelo cuantitativo que puede servir para descifrar las elaboradas rutas involucradas en la cardiomiogénesis. Esta aproximación podría revelar la etiología de los defectos cardíacos y permitiría producir cardiomiocitos con propósitos clínicos en la regeneracíon y la toxicología entre otros (AU)
No disponible
Subject(s)
Humans , Heart/embryology , Cell- and Tissue-Based Therapy/methods , Myocytes, Cardiac , Calcium Signaling/physiology , Regeneration/physiology , Embryonic Stem Cells , Gene Expression , Cell Differentiation/physiologyABSTRACT
The cyanobacterial metabolite apratoxin A (1) demonstrates potent cytotoxicity against tumor cell lines by a hitherto unknown mechanism. We have used functional genomics to elucidate the molecular basis for this activity. Gene expression profiling and DNA content analysis showed that apratoxin A induces G1-phase cell cycle arrest and apoptosis. Cell-based functional assays with a genome-wide collection of expression cDNAs showed that ectopic induction of fibroblast growth factor receptor (FGFR) signaling attenuates the apoptotic activity of apratoxin A. This natural product inhibited phosphorylation and activation of STAT3, a downstream effector of FGFR signaling. It also caused defects in FGF-dependent processes during zebrafish development, with concomitant reductions in expression levels of the FGF target gene mkp3. We conclude that apratoxin A mediates its antiproliferative activity through the induction of G1 cell cycle arrest and an apoptotic cascade, which is at least partially initiated through antagonism of FGF signaling via STAT3.
Subject(s)
Cell Cycle/drug effects , Depsipeptides/pharmacology , Genomics/methods , Animals , Apoptosis/drug effects , Cell Cycle/genetics , Cell Proliferation/drug effects , Drug Resistance, Neoplasm , Endothelial Cells/drug effects , Fibroblast Growth Factors/antagonists & inhibitors , Fibroblast Growth Factors/metabolism , G1 Phase/drug effects , Gene Expression Regulation/drug effects , Humans , In Vitro Techniques , Molecular Conformation , Phosphorylation , RNA, Messenger/drug effects , RNA, Messenger/genetics , STAT3 Transcription Factor/drug effects , STAT3 Transcription Factor/metabolism , Signal Transduction/drug effects , Signal Transduction/physiology , Structure-Activity Relationship , Transcription, Genetic/drug effects , Tumor Cells, Cultured , Zebrafish/embryologyABSTRACT
During embryogenesis, cells are spatially patterned as a result of highly coordinated and stereotyped morphogenetic events. In the vertebrate embryo, information on laterality is conveyed to the node, and subsequently to the lateral plate mesoderm, by a complex cascade of epigenetic and genetic events, eventually leading to a left-right asymmetric body plan. At the same time, the paraxial mesoderm is patterned along the anterior-posterior axis in metameric units, or somites, in a bilaterally symmetric fashion. Here we characterize a cascade of laterality information in the zebrafish embryo and show that blocking the early steps of this cascade (before it reaches the lateral plate mesoderm) results in random left-right asymmetric somitogenesis. We also uncover a mechanism mediated by retinoic acid signalling that is crucial in buffering the influence of the flow of laterality information on the left-right progression of somite formation, and thus in ensuring bilaterally symmetric somitogenesis.
Subject(s)
Body Patterning/physiology , Embryo, Nonmammalian/metabolism , Signal Transduction , Somites/metabolism , Tretinoin/metabolism , Zebrafish/embryology , Zebrafish/metabolism , Animals , Cilia/physiology , Embryo, Nonmammalian/embryology , Models, Biological , Molecular Sequence Data , Somites/cytology , Zebrafish/geneticsABSTRACT
Several vertebrates display the ability to regenerate parts of their body after amputation. During this process, differentiated cells reenter the cell cycle and proliferate to generate a mass of undifferentiated cells. Repatterning mechanisms act on these cells to eventually shape a regenerated tissue or organ that replaces the amputated one. Experiments with regenerating limbs/fins in newts and zebrafish have shown that members of the Msx family of homeodomain-containing transcription factors play key roles during blastema formation and patterning. Here we show that adult zebrafish have a remarkable capacity to regenerate the heart in a process that involves up-regulation of msxB and msxC genes. We present evidence indicating that heart regeneration involves the execution of a specific genetic program, rather than redeployment of a cardiac development program. Preceding Msx activation, there is a marked increase in the expression of notch1b and deltaC, which we show are also up-regulated during fin regeneration. These data suggest a role for the Notch pathway in the activation of the regenerative response. Taken together, our results underscore the use of zebrafish as a model for investigating the process of regeneration in particular and the biology of stem cells in general. Advances in these fields will undoubtedly aid in the implementation of strategies for regenerative medicine.
Subject(s)
Heart/physiology , Membrane Proteins/physiology , Regeneration , Zebrafish/physiology , Animals , Animals, Genetically Modified , Heart/growth & development , Homeodomain Proteins/genetics , In Situ Hybridization , Membrane Proteins/genetics , Models, Biological , Receptors, Notch , Regeneration/genetics , Regeneration/physiology , Signal Transduction , Transcription Factors/genetics , Up-Regulation , Zebrafish/genetics , Zebrafish Proteins/geneticsABSTRACT
Left-sided expression of Nodal in the lateral plate mesoderm is a conserved feature necessary for the establishment of normal left-right asymmetry during vertebrate embryogenesis. By using gain- and loss-of-function experiments in zebrafish and mouse, we show that the activity of the Notch pathway is necessary and sufficient for Nodal expression around the node, and for proper left-right determination. We identify Notch-responsive elements in the Nodal promoter, and unveil a direct relationship between Notch activity and Nodal expression around the node. Our findings provide evidence for a mechanism involving Notch activity that translates an initial symmetry-breaking event into asymmetric gene expression.
