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Gene Review

Abd-B  -  Abdominal B

Drosophila melanogaster

Synonyms: ABD-B, ABDB, Abd B, Abd-b, Abd0B, ...
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Disease relevance of Abd-B

  • In lines mutant embryos Abdominal-B protein expression is normal but incapable of promoting its normal functions: formation of the posterior spiracles and specification of an eighth abdominal denticle belt [1].
  • Also, group XVII, which became vacant when strain DF-1T (Spiroplasma chrysopicola) was transferred to group VIII, has been filled with strain Tab 4c [2].

High impact information on Abd-B

  • Moreover, this methylation pattern is found primarily in the tissues where Abd-B is not expressed and requires an intact Fab-7 boundary [3].
  • We show here that components of the RNA interference (RNAi) machinery are involved in PcG-mediated silencing at Fab-7 and in the production of small RNAs at transgenic Fab-7 copies [4].
  • Fab-7 is a PRE-containing regulatory element from the homeotic gene Abdominal-B [4].
  • When present in multiple copies in the genome, Fab-7 can induce long-distance gene contacts that enhance PcG-dependent silencing [4].
  • One other Hox gene, Abdominal-B (Abd-B), also regulates segment boundaries through the regional activation of apoptosis [5].

Biological context of Abd-B

  • The Abd-B gene may provide a model for the understanding of similarly complex homeotic genes in higher organisms [6].
  • The genotype deficient for the distal part of the complex shows normal function for Ubx and abd-A but has a phenotype typical for severe Abd-B mutations [7].
  • It therefore contained all sequences of the BX-C though in the abdominal region the abd-A and Abd-B domains were not adjacent to each other in the chromosome [7].
  • Transvection depends on an approx. 10 kb genomic DNA sequence, termed the transvection mediating region (tmr), located immediately downstream of the Abd-B transcription unit [8].
  • The lack of requirement for local synapsis and the tenacity of trans-interaction argue that the iab-5,6,7 region can locate and interact with Abd-B over considerable distance [9].

Anatomical context of Abd-B

  • The genitalia of Drosophila derive from the genital disc and require the activity of the Abdominal-B (Abd-B) Hox gene [10].
  • We also show that Abd-B, which at earlier stages is expressed posteriorly to the cardiogenic mesoderm, represses cardiogenesis [11].
  • In Abd-B mutants, the msSGPs are not specified and male gonads now resemble female gonads with respect to these cells [12].
  • In Tab/+ animals ABD-BII is ectopically expressed in the relevant imaginal "wing" disc as three islands of cells whose location on the fate map corresponds to the three islands of transformed cuticle in each half of the adult thorax [13].
  • In blastoderm stage embryos we can define three distinct domains within the iab DNA, each transcribed in a region that extends from a characteristic anterior limit to the posterior end of the segmented part of the embryo [14].

Physical interactions of Abd-B

  • The Drosophila bithorax complex Abdominal-B (Abd-B) gene specifies parasegmental identity at the posterior end of the fly [15].
  • Using two different transgene assays we demonstrate that GAGA-factor-binding sites are necessary but not sufficient for full Fab-7 enhancer-blocking activity [16].
  • Conversely, we find that the Abdominal-B gene is active in these cells and the region devoid of any bound Pc protein [17].
  • We show that GAGA and Pho interact with these sequences in vitro and that the consensus binding sites for the two proteins are critical for the silencing activity of the iab-7 PRE in vivo [18].

Regulatory relationships of Abd-B

  • In the male A9, some Abd-B m(-)r(-) or Abd-B r(-) clones activate Distal-less and transform part of the genitalia into leg or antenna [10].
  • Here, we show that mutant alleles of Trl, dsap18 and drpd3/hdac1 enhance A6-to-A5 transformation indicating a contribution to the regulation of Abd-B expression at A6 [19].
  • In segment A9 the highly expressed Ubx product is phenotypically suppressed by the r product of Abdominal-B [20].
  • Here, we show that ems is a downstream gene that is transcriptionally regulated by Abd-B proteins [21].
  • These Abd-B-type Hox genes have been shown to be expressed in the most caudal regions of the developing vertebrate embryo and in overlapping domains within the developing limbs, suggesting that these genes play important roles in pattern formation in both appendicular and axial regions of the body [22].

Other interactions of Abd-B

  • The abdA homeo box is almost identical to the homeo box of Ubx but is quite different from the AbdB homeo box [23].
  • The molecular genetics of the bithorax complex of Drosophila: cis-regulation in the Abdominal-B domain [24].
  • Embryos homozygous for Polycomb (Pc) show labeling over almost the entire embryo, whereas embryos deficient for the Abd-B domain show no detectable labeling [25].
  • We discuss the significance of these findings with regard to Abd-B transvection and long-range enhancer-promoter interactions in mammalian globin loci [8].
  • However, in contrast to Ubx, the transvection we observed in the Abd-B locus is insensitive to the allelic status of zeste [26].

Analytical, diagnostic and therapeutic context of Abd-B


  1. The lines gene of Drosophila is required for specific functions of the Abdominal-B HOX protein. Castelli-Gair, J. Development (1998) [Pubmed]
  2. Revised group classification of the genus Spiroplasma. Williamson, D.L., Whitcomb, R.F., Tully, J.G., Gasparich, G.E., Rose, D.L., Carle, P., Bové, J.M., Hackett, K.J., Adams, J.R., Henegar, R.B., Konai, M., Chastel, C., French, F.E. Int. J. Syst. Bacteriol. (1998) [Pubmed]
  3. Probing long-distance regulatory interactions in the Drosophila melanogaster bithorax complex using Dam identification. Cléard, F., Moshkin, Y., Karch, F., Maeda, R.K. Nat. Genet. (2006) [Pubmed]
  4. RNAi components are required for nuclear clustering of Polycomb group response elements. Grimaud, C., Bantignies, F., Pal-Bhadra, M., Ghana, P., Bhadra, U., Cavalli, G. Cell (2006) [Pubmed]
  5. The Drosophila Hox gene deformed sculpts head morphology via direct regulation of the apoptosis activator reaper. Lohmann, I., McGinnis, N., Bodmer, M., McGinnis, W. Cell (2002) [Pubmed]
  6. Molecular definition of the morphogenetic and regulatory functions and the cis-regulatory elements of the Drosophila Abd-B homeotic gene. Boulet, A.M., Lloyd, A., Sakonju, S. Development (1991) [Pubmed]
  7. Chromosomal continuity in the abdominal region of the bithorax complex of Drosophila is not essential for its contribution to metameric identity. Tiong, S.Y., Whittle, J.R., Gribbin, M.C. Development (1987) [Pubmed]
  8. Characterization of the transvection mediating region of the abdominal-B locus in Drosophila. Zhou, J., Ashe, H., Burks, C., Levine, M. Development (1999) [Pubmed]
  9. Transvection in the iab-5,6,7 region of the bithorax complex of Drosophila: homology independent interactions in trans. Hopmann, R., Duncan, D., Duncan, I. Genetics (1995) [Pubmed]
  10. Requirement of Abdominal-A and Abdominal-B in the developing genitalia of Drosophila breaks the posterior downregulation rule. Foronda, D., Estrada, B., de Navas, L., Sánchez-Herrero, E. Development (2006) [Pubmed]
  11. Homeotic genes autonomously specify the anteroposterior subdivision of the Drosophila dorsal vessel into aorta and heart. Lo, P.C., Skeath, J.B., Gajewski, K., Schulz, R.A., Frasch, M. Dev. Biol. (2002) [Pubmed]
  12. Abdominal-B is essential for proper sexually dimorphic development of the Drosophila gonad. DeFalco, T., Le Bras, S., Van Doren, M. Mech. Dev. (2004) [Pubmed]
  13. Molecular basis of transabdominal--a sexually dimorphic mutant of the bithorax complex of Drosophila. Celniker, S.E., Lewis, E.B. Proc. Natl. Acad. Sci. U.S.A. (1993) [Pubmed]
  14. Spatially ordered transcription of regulatory DNA in the bithorax complex of Drosophila. Sánchez-Herrero, E., Akam, M. Development (1989) [Pubmed]
  15. The Fab-8 boundary defines the distal limit of the bithorax complex iab-7 domain and insulates iab-7 from initiation elements and a PRE in the adjacent iab-8 domain. Barges, S., Mihaly, J., Galloni, M., Hagstrom, K., Müller, M., Shanower, G., Schedl, P., Gyurkovics, H., Karch, F. Development (2000) [Pubmed]
  16. The enhancer-blocking activity of the Fab-7 boundary from the Drosophila bithorax complex requires GAGA-factor-binding sites. Schweinsberg, S., Hagstrom, K., Gohl, D., Schedl, P., Kumar, R.P., Mishra, R., Karch, F. Genetics (2004) [Pubmed]
  17. Mapping Polycomb-repressed domains in the bithorax complex using in vivo formaldehyde cross-linked chromatin. Orlando, V., Paro, R. Cell (1993) [Pubmed]
  18. The iab-7 polycomb response element maps to a nucleosome-free region of chromatin and requires both GAGA and pleiohomeotic for silencing activity. Mishra, R.K., Mihaly, J., Barges, S., Spierer, A., Karch, F., Hagstrom, K., Schweinsberg, S.E., Schedl, P. Mol. Cell. Biol. (2001) [Pubmed]
  19. dSAP18 and dHDAC1 contribute to the functional regulation of the Drosophila Fab-7 element. Canudas, S., Pérez, S., Fanti, L., Pimpinelli, S., Singh, N., Hanes, S.D., Azorín, F., Espinás, M.L. Nucleic Acids Res. (2005) [Pubmed]
  20. The developmental effect of overexpressing a Ubx product in Drosophila embryos is dependent on its interactions with other homeotic products. González-Reyes, A., Morata, G. Cell (1990) [Pubmed]
  21. The regulation of empty spiracles by Abdominal-B mediates an abdominal segment identity function. Jones, B., McGinnis, W. Genes Dev. (1993) [Pubmed]
  22. Homeotic transformations and limb defects in Hox A11 mutant mice. Small, K.M., Potter, S.S. Genes Dev. (1993) [Pubmed]
  23. abdA expression in Drosophila embryos. Karch, F., Bender, W., Weiffenbach, B. Genes Dev. (1990) [Pubmed]
  24. The molecular genetics of the bithorax complex of Drosophila: cis-regulation in the Abdominal-B domain. Celniker, S.E., Sharma, S., Keelan, D.J., Lewis, E.B. EMBO J. (1990) [Pubmed]
  25. The molecular genetics of the bithorax complex of Drosophila: characterization of the products of the Abdominal-B domain. Celniker, S.E., Keelan, D.J., Lewis, E.B. Genes Dev. (1989) [Pubmed]
  26. Transvection in the Drosophila Abd-B domain: extensive upstream sequences are involved in anchoring distant cis-regulatory regions to the promoter. Sipos, L., Mihály, J., Karch, F., Schedl, P., Gausz, J., Gyurkovics, H. Genetics (1998) [Pubmed]
  27. In situ dissection of the Fab-7 region of the bithorax complex into a chromatin domain boundary and a Polycomb-response element. Mihaly, J., Hogga, I., Gausz, J., Gyurkovics, H., Karch, F. Development (1997) [Pubmed]
  28. Tumorous-head (tuh-1; tuh-3) modulates Abd-B bithorax-complex functions in Drosophila melanogaster. Kuhn, D.T., Mack, J.A., Duan, C., Packert, G. Genetics (1993) [Pubmed]
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