GENETIC CONTROL OF SEGMENTATION
Susan J Brown
Kansas State University, 2 Fairchild Hall, Manhattan, Ks 66506-1103
Grant 5R01HD029594-18 from Eunice Kennedy Shriver National Institute Of Child Health & Human Development
Abstract: The clock and wavefront mechanisms underlying segmentation in vertebrates and the genetic hierarchy regulating segmentation in Drosophila seemingly imply independent origins of metameric development. However, comparative studies in non-drosophilid insects and other arthropods provide increasing molecular evidence for a common ancestry. In Drosophila, segments are patterned simultaneously. In most other insects including the red flour beetle Tribolium castaneum, other arthropods and vertebrates, segmentation is a longer process that occurs progressively from anterior to posterior. To understand the molecular mechanisms driving sequential metamerism and identify new genes important to this process, we are studying the genetic regulation of segmentation in Tribolium. In Tribolium, abdominal segments arise from a posterior growth zone during germband elongation, and RNAi with several early patterning genes truncates segmentation from the growth zone, suggesting this is an important regulation point. We have identified a gene circuit of primary pair-rule genes that functions to generate segments sequentially. Defects in its components disrupt the gene circuit and truncate the segmentation process. Periodic expression of two genes in this circuit initiates as twin spots in the posterior growth zone and may be regulated by early patterning genes. In addition, we have found that TcWnt8 is expressed in twin spots in the posterior growth zone, and TcWnt8 RNAi embryos are truncated in the thorax. We hypothesize that segmentation and elongation may be regulated by posterior signals that control components of the pair-rule gene circuit and/or proliferation. We will combine genetic and molecular approaches to analyze the relationship of cell proliferation, convergent extension and posterior signaling to segmentation, all of which are fundamental to embryonic elongation in vertebrates and arthropods. The genetic and genomic tools we have developed, combined with the Tribolium genome sequence, provide a unique opportunity to identify, regulatory genes and molecular processes which may represent presently unrecognized, developmentally significant mammalian counterparts important to segmentation. Our studies have the potential to provide new insight into human birth defects in spinal development and cancers related to misregulation of signaling mechanisms
Keywords: Abdomen; Abdominal; Anterior; Arthropoda; Arthropods; Automobile Driving; Birth Defects; Cancers; Cell Communication and Signaling; Cell Growth in Number; Cell Locomotion; Cell Migration; Cell Movement; Cell Multiplication; Cell Polarity; Cell Proliferation; Cell Signaling; Cell division; Cellular Migration; Cellular Proliferation; Chest; Comparative Study; Congenital Abnormality; Congenital Anatomic Abnormality; Congenital Anatomical Abnormality; Congenital Defects; Congenital Deformity; Congenital Malformation; DNA Synthesis Factor; Defect; Development; Drivings, Automobile; Drosophila; Drosophila genus; ECGF; Embryo; Embryonic; Endothelial Cell Growth Factor; FGF; Fibroblast Growth Factor; Fibroblast Growth Regulatory Factor; Flour; Fruit Fly, Drosophila; GeneHomolog; Generalized Growth; Genes; Genes, Regulator; Genetic; Genomics; Growth; HBGF; Homolog; Homologous Gene; Homologue; Human; Human, General; Insecta; Insects; Intracellular Communication and Signaling; Invertebrates, Insects; Investigators; JNK; JNK1; JNK1A2; JNK21B1/2; Lead; Ligands; MAP Kinase 8 Gene; MAPK8; MAPK8 gene; Malignant Neoplasms; Malignant Tumor; Man (Taxonomy); Man, Modern; Mediator; Mediator of Activation; Mediator of activation protein; Messenger RNA; Modeling; Molecular; Molecular Genetic; Molecular Genetic Abnormality; Molecular Genetics; Motility; Motility, Cellular; Notch Signaling Pathway; Nuclear; PRKM8; Pathway interactions; Pattern; Pb element; Position; Positioning Attribute; Post-Transcriptional Gene Silencing; Post-Transcriptional Gene Silencings; Posttranscriptional Gene Silencing; Posttranscriptional Gene Silencings; Process; Programs (PT); Programs [Publication Type]; Proteolysis and Signaling Pathway of Notch; Quelling; RNA Interference; RNA Silencing; RNA Silencings; RNA, Messenger; RNAi; Regulation; Regulator Genes; Research Personnel; Researchers; Role; SAPK1; Screening procedure; Sequence-Specific Posttranscriptional Gene Silencing; Signal Pathway; Signal Transduction; Signal Transduction Systems; Signaling; Spinal; Spottings; Survey Instrument; Surveys; Thorace; Thoracic; Thorax; Tissue Growth; Transcription Activation; Transcriptional Activation; Transcriptional Regulatory Elements; Tribolium; Tribolium (beetle); Twin Multiple Birth; Twins; Up-Regulation; Vertebrate Animals; Vertebrates; biological signal transduction; cell motility; cellular polarity; driving; fruit fly; gene function; genome sequencing; heavy metal Pb; heavy metal lead; insight; mRNA; malignancy; neoplasm/cancer; ontogeny; overexpression; pathway; programs; regulatory gene; screening; screenings; social role; tool; trans acting element; vertebrata
Project start date: 1992-08-01
Project end date: 2012-06-30
Budget start date: 1-JUL-2009
Budget end date: 30-JUN-2010
5R01HD029594-18 (2009): $273641
Sponsored Links Excellgen http://Excellgen.com
Genetic Control Of Segmentation
Susan J Brown, Associate Professor
Kansas State University 2 Fairchild Hall Manhattan, Ks 665061103
Grant 5R01HD029594-15 from National Institute Of Child Health And Human Development IRG: GEN
Abstract: Through comparative studies between distantly related animals, it has become apparent that genes and regulatory networks functioning during embryonic growth are highly conserved. This has led to the hypothesis that evolutionary changes in morphology can be traced to alterations in these regulatory modules. Studies to address this hypothesis have focused on insects, which display different modes of segmentation. Most approaches rely on cloning and expression analysis of orthologs of well-characterized Drosophila genes. However, most insects do not offer facile approaches to examine the functional significance of conserved gene expression patterns, or to test observed differences. Further, these comparisons are limited to the analysis of mechanisms discovered in flies, and do not offer the possibility of identifying genes important to segmentation in species other than flies. Our studies in Tribolium overcome these limitations, since Tribolium offers the possibility of genetic manipulation in addition to its facility for developmental and molecular studies. Moreover, the recent advances in RNA interference and germline transformation place Tribolium in the forefront of comparative model systems. We have discovered that depletion of certain pair-rule gene mRNAs by RNAi blocks segmentation and morphogenesis in Tribolium, results not predicted by the Drosophila paradigm. To understand the molecular interaction underlying these novel phenotypes we will examine the effects of Tceve and Tcrun mRNA depletion on the expression of other segmentation and homeotic genes. Analysis of the regulatory regions associated with these genes and ectopic expression of transgenes will complement the RNAi studies. To discover other genes important to segmentation in Tribolium we will execute a transposon-tagging mutagenesis scheme and characterize relevant mutants. Our research provides a unique opportunity to elucidate the genetic mechanisms underlying the regulation of the process of progressive segmentation in a cellular environment.
Keywords: Coleoptera, body region, developmental genetics, early embryonic stage, embryogenesis, gene expression, homeobox gene, cytogenetics, gene interaction, gene mutation, genetic mapping, genetic regulation, protein structure function, regulatory gene, species difference, genetic library, genetic manipulation, in situ hybridization, molecular cloning, polymerase chain reaction, southern blotting, western blotting
Project start date: 1992-08-01
Project end date: 2007-08-02
5R01HD029594-15 (2006): $287714
5R01HD029594-14 (2005): $294638
5R01HD029594-13 (2004): $290543
5R01HD029594-12 (2003): $290543
5R01HD029594-17 (2008): $273641
Grants awarded to Susan J Brown
Genetic Control Of Segmentation
Susan J Brown, Associate Professor
Kansas State University 2 Fairchild Hall Manhattan, Ks 665061103
Grant 2R01HD029594-11 from National Institute Of Child Health And Human Development IRG: GEN
Abstract: Through comparative studies between distantly related animals, it has become apparent that genes and regulatory networks functioning during embryonic growth are highly conserved. This has led to the hypothesis that evolutionary changes in morphology can be traced to alterations in these regulatory modules. Studies to address this hypothesis have focused on insects, which display different modes of segmentation. Most approaches rely on cloning and expression analysis of orthologs of well-characterized Drosophila genes. However, most insects do not offer facile approaches to examine the functional significance of conserved gene expression patterns, or to test observed differences. Further, these comparisons are limited to the analysis of mechanisms discovered in flies, and do not offer the possibility of identifying genes important to segmentation in species other than flies. Our studies in Tribolium overcome these limitations, since Tribolium offers the possibility of genetic manipulation in addition to its facility for developmental and molecular studies. Moreover, the recent advances in RNA interference and germline transformation place Tribolium in the forefront of comparative model systems. We have discovered that depletion of certain pair-rule gene mRNAs by RNAi blocks segmentation and morphogenesis in Tribolium, results not predicted by the Drosophila paradigm. To understand the molecular interaction underlying these novel phenotypes we will examine the effects of Tceve and Tcrun mRNA depletion on the expression of other segmentation and homeotic genes. Analysis of the regulatory regions associated with these genes and ectopic expression of transgenes will complement the RNAi studies. To discover other genes important to segmentation in Tribolium we will execute a transposon-tagging mutagenesis scheme and characterize relevant mutants. Our research provides a unique opportunity to elucidate the genetic mechanisms underlying the regulation of the process of progressive segmentation in a cellular environment.
Keywords: Coleoptera, body region, developmental genetics, early embryonic stage, embryogenesis, gene expression, homeobox gene, cytogenetics, gene interaction, gene mutation, genetic mapping, genetic regulation, protein structure function, regulatory gene, species difference, genetic library, genetic manipulation, in situ hybridization, molecular cloning, polymerase chain reaction, southern blotting, western blotting
Project start date: 1992-08-01
Project end date: 2007-07-31
2R01HD029594-11 (2002): $284400
2R01HD029594-16 (2007): $279225