Two ParaHox genes, SpLox and SpCdx, interact to partition the posterior endoderm in the formation of a functional gut

We report the characterization of the ortholog of the Xenopus XlHbox8 ParaHox gene from the sea urchin Strongylocentrotus purpuratus, SpLox. It is expressed during embryogenesis, first appearing at late gastrulation in the posterior-most region of the endodermal tube, becoming progressively restricted to the constriction between the mid- and hindgut. The physiological effects of the absence of the activity of this gene have been analyzed through knockdown experiments using gene-specific morpholino antisense oligonucleotides. We show that blocking the translation of the SpLox mRNA reduces the capacity of the digestive tract to process food, as well as eliminating the morphological constriction normally present between the mid- and hindgut. Genetic interactions of the SpLox gene are revealed by the analysis of the expression of a set of genes involved in endoderm specification. Two such interactions have been analyzed in more detail: one involving the midgut marker gene Endo16, and another involving the other endodermally expressed ParaHox gene, SpCdx. We find that SpLox is able to bind Endo16 cis-regulatory DNA, suggesting direct repression of Endo16 expression in presumptive hindgut territories. More significantly, we provide the first evidence of interaction between ParaHox genes in establishing hindgut identity, and present a model of gene regulation involving a negative-feedback loop.

[1]  R. Cameron,et al.  The larval stages of the sea urchin, Strongylocentrotus purpuratus , 2008, Journal of morphology.

[2]  M. Montenarh,et al.  Pancreatic duodenal homeobox factor-1 and diabetes mellitus type 2 (review). , 2008, International journal of molecular medicine.

[3]  A. Galione,et al.  Flipping the switch: How a sperm activates the egg at fertilization , 2007, Developmental dynamics : an official publication of the American Association of Anatomists.

[4]  M. Arnone,et al.  Genetic organization and embryonic expression of the ParaHox genes in the sea urchin S. purpuratus: insights into the relationship between clustering and colinearity. , 2006, Developmental biology.

[5]  G. Wessel,et al.  In the beginning...animal fertilization and sea urchin development. , 2006, Developmental biology.

[6]  Andrew R. Jackson,et al.  The Genome of the Sea Urchin Strongylocentrotus purpuratus , 2006, Science.

[7]  Eric H Davidson,et al.  Repression of mesodermal fate by foxa, a key endoderm regulator of the sea urchin embryo , 2006, Development.

[8]  E. Davidson,et al.  cis-regulatory processing of Notch signaling input to the sea urchin glial cells missing gene during mesoderm specification. , 2006, Developmental biology.

[9]  Eric H Davidson,et al.  Hindgut specification and cell‐adhesion functions of Sphox11/13b in the endoderm of the sea urchin embryo , 2006, Development, growth & differentiation.

[10]  Eric H Davidson,et al.  Expression and function of blimp1/krox, an alternatively transcribed regulatory gene of the sea urchin endomesoderm network. , 2006, Developmental biology.

[11]  M. A. Biscotti,et al.  All the three ParaHox genes are present in Nuttallochiton mirandus (Mollusca: polyplacophora): evolutionary considerations. , 2006, Journal of experimental zoology. Part B, Molecular and developmental evolution.

[12]  E. Seaver,et al.  ParaHox gene expression in the polychaete annelid Capitella sp. I , 2006, Development Genes and Evolution.

[13]  Eric H Davidson,et al.  Brn1/2/4, the predicted midgut regulator of the endo16 gene of the sea urchin embryo. , 2005, Developmental biology.

[14]  E. Davidson,et al.  Expression of Spgatae, the Strongylocentrotus purpuratus ortholog of vertebrate GATA4/5/6 factors. , 2004, Gene expression patterns : GEP.

[15]  L. Olds,et al.  Transcriptional regulation of the lactase-phlorizin hydrolase promoter by PDX-1. , 2004, American journal of physiology. Gastrointestinal and liver physiology.

[16]  Eric H Davidson,et al.  Expression patterns of four different regulatory genes that function during sea urchin development. , 2004, Gene expression patterns : GEP.

[17]  Jing Chen,et al.  Nuclear β‐catenin‐dependent Wnt8 signaling in vegetal cells of the early sea urchin embryo regulates gastrulation and differentiation of endoderm and mesodermal cell lineages , 2004 .

[18]  A. Liberzon,et al.  Role of intrinsic DNA binding specificity in defining target genes of the mammalian transcription factor PDX1. , 2004, Nucleic acids research.

[19]  Bruce Aronow,et al.  Global expression analysis of gene regulatory pathways during endocrine pancreatic development , 2004, Development.

[20]  E. Davidson,et al.  Isolation of pigment cell specific genes in the sea urchin embryo by differential macroarray screening , 2003, Development.

[21]  Eric H Davidson,et al.  Activation of pmar1 controls specification of micromeres in the sea urchin embryo. , 2003, Developmental biology.

[22]  Chaolun Allen Chen,et al.  Novel pattern of AtXlox gene expression in starfish Archaster typicus embryos , 2003, Development, growth & differentiation.

[23]  Eric H Davidson,et al.  A provisional regulatory gene network for specification of endomesoderm in the sea urchin embryo. , 2002, Developmental biology.

[24]  E. Davidson,et al.  brachyury Target genes in the early sea urchin embryo isolated by differential macroarray screening. , 2002, Developmental biology.

[25]  M. Fujimiya,et al.  Combined expression of pancreatic duodenal homeobox 1 and islet factor 1 induces immature enterocytes to produce insulin. , 2002, Diabetes.

[26]  E. Davidson,et al.  Evidence for a mesodermal embryonic regulator of the sea urchin CyIIa gene. , 2001, Developmental biology.

[27]  E. Davidson,et al.  Recovery of developmentally defined gene sets from high-density cDNA macroarrays. , 2000, Developmental biology.

[28]  J. M. Venuti,et al.  Expression of the sea urchin MyoD homologue, SUM1, is not restricted to the myogenic lineage during embryogenesis , 1999, Mechanisms of Development.

[29]  C Q Doe,et al.  Dorsoventral patterning in the Drosophila central nervous system: the intermediate neuroblasts defective homeobox gene specifies intermediate column identity. , 1998, Genes & development.

[30]  C. Doe,et al.  Dorsoventral patterning in the Drosophila central nervous system: the vnd homeobox gene specifies ventral column identity. , 1998, Genes & development.

[31]  J. Habener,et al.  Misexpression of the pancreatic homeodomain protein IDX-1 by the Hoxa-4 promoter associated with agenesis of the cecum. , 1998, Gastroenterology.

[32]  L. -. Wu,et al.  Role of caudal in hindgut specification and gastrulation suggests homology between Drosophila amnioproctodeal invagination and vertebrate blastopore. , 1998, Development.

[33]  N. M. Brooke,et al.  The ParaHox gene cluster is an evolutionary sister of the Hox gene cluster , 1998, Nature.

[34]  E. Davidson,et al.  Cis-regulation downstream of cell type specification: a single compact element controls the complex expression of the CyIIa gene in sea urchin embryos. , 1998, Development.

[35]  E. Davidson,et al.  Genomic cis-regulatory logic: experimental and computational analysis of a sea urchin gene. , 1998, Science.

[36]  R. Krumlauf,et al.  Cross-regulation in the mouse HoxB complex: the expression of Hoxb2 in rhombomere 4 is regulated by Hoxb1. , 1997, Genes & development.

[37]  B. Hogan,et al.  PDX-1 is required for pancreatic outgrowth and differentiation of the rostral duodenum. , 1996, Development.

[38]  H. Edlund,et al.  Insulin-promoter-factor 1 is required for pancreas development in mice , 1994, Nature.

[39]  R. Burke,et al.  Endo16, a large multidomain protein found on the surface and ECM of endodermal cells during sea urchin gastrulation, binds calcium. , 1994, Developmental biology.

[40]  R. Britten,et al.  Complexity and organization of DNA-protein interactions in the 5′-regulatory region of an endoderm-specific marker gene in the sea urchin embryo , 1994, Mechanisms of Development.

[41]  R. Britten,et al.  Whole mount in situ hybridization shows Endo 16 to be a marker for the vegetal plate territory in sea urchin embryos , 1993, Mechanisms of Development.

[42]  E. Rondinelli,et al.  Polyubiquitin RNA characteristics and conditional induction in sea urchin embryos. , 1991, Developmental biology.

[43]  B. Livingston,et al.  Lithium evokes expression of vegetal-specific molecules in the animal blastomeres of sea urchin embryos. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[44]  P. Schnegelsberg,et al.  XlHbox 8: a novel Xenopus homeo protein restricted to a narrow band of endoderm. , 1989, Development.

[45]  J. J. Lee,et al.  Cell lineage-specific programs of expression of multiple actin genes during sea urchin embryogenesis. , 1986, Journal of molecular biology.

[46]  W. Gehring,et al.  Isolation of caudal, a Drosophila homeo box‐containing gene with maternal expression, whose transcripts form a concentration gradient at the pre‐blastoderm stage , 1985, The EMBO journal.

[47]  D. McClay,et al.  Sequential expression of germ-layer specific molecules in the sea urchin embryo. , 1985, Developmental biology.

[48]  C. Ettensohn.  Primary Invagination of the Vegetal Plate During Sea Urchin Gastrulation , 1984 .

[49]  C. E. Cook,et al.  BMC Developmental Biology BioMed Central Research article , 2008 .

[50]  R. Krumlauf,et al.  Cross-regulation in the mouse HoxB , 2007 .

[51]  J. Garcia-Fernández,et al.  Hox and ParaHox genes in Nemertodermatida, a basal bilaterian clade. , 2006, The International journal of developmental biology.

[52]  J. Habener,et al.  Developmental expression of the homeodomain protein IDX-1 in mice transgenic for an IDX-1 promoter/lacZ transcriptional reporter. , 1999, Endocrinology.

[53]  J. Hardin.  The cellular basis of sea urchin gastrulation. , 1996, Current topics in developmental biology.

[54]  J. Hardin.  4 The Cellular Basis of Sea Urchin Gastrulation , 1996 .