Ectopic expression

Causalgia is burning pain evoked by the activation of sympathetic efferent fibres. The likely mechanism underlying this syndrome involves ectopic expression of a-adrenoceptors on nociceptive afferents following peripheral injury or disease. 

Extrahypothalamic OX-B-like immunoreactivity, reminiscent to that of CRF, has been described in clustered GABAergic neuronal populations, in the lateral division of central nucleus ofthe amygdala, the bednucleus of the stria terminalis, and in the hippocampus. Moreover, ectopic expression of preproorexin mRNA in the gut, ependymal cells, neuroblastomas, and of orexin receptors in adrenal gland, cancer and hematopietic stem cells suggests yet unexplored roles of orexins as paracrine factors controlling blood-brain barrier, and tumor or stem cell function. 

The first clue to a role for Wnt/(3-catenin-dependent signaling in vertebrate development came from overexpression studies in the classical embryonic system, the frog Xenopus loevis. When Wntl is ectopically expressed in cells that would normally contribute to the ventral embryo (i.e. the future belly), they instead adopt... 

Hinds, P. H., Mittnacht, S., Dulic, V., Arnold, A., Reed, S. I., and Weilberg, R. A. (1992). Regulation of the retinoblastoma protein functions by ectopic expression of human cyclins. Cell 70 993-1006. 

Lufkin et al. (1992) also used a homeobox gene promoter exchange to drive misexpression of the Hox-4.2 gene. The Hox-1.6 promoter was observed to extend the anterior transcription boundary, and this region of ectopic expression gave a number of abnormalities, including absence... 

The most dramatic illustration of the evolutionary conservation of homeobox genes comes from experiments that swap Drosophila and mammalian cognates and test for functional equivalence. McGinnis and co-workers have reported remarkable phenotypic similarities in flies that misexpress Drosophila homeobox genes or their mammalian counterparts. Indeed, this ectopic expression assay in Drosophila indicates that the Drosophila and cognate mammalian homeobox proteins are essentially functionally identical. 

Balling, R., Mutter, G., Gruss, R, and Kessel, M. (1989). Craniofacial abnormalities induced by ectopic expression of the homeobox gene Hox-1.1 in transgenic mice. Cell 58 337-347. 

Gibson, G., and Gehring, W. J. (1988). Head and thoracic transformations caused by ectopic expression of Antennapedia during Drosophila development. Development 102 657-675. 

Lufkin, T., Mark, M., Hart, C. P Dolle, R, LeMeur, M., and Chambon, P. (1992). Homeotic transformation of the occipital bones of the skull by ectopic expression of a homeobox gene. Nature 359 835-841. 

McLain, K., Schreiner, C., Yager, K., Stock, J., and Potter, S. (1992). Ectopic expression of Hox-2.3 induces craniofacial and skeletal malformations in transgenic mice. Mech. Dev. 39 3-16. 

Schneuwly, S., Klemenz, R and Gehring, W. J. (1987). Redesigning the body plan of Drosophila by ectopic expression of the homeotic gene Antennapedia. Nature 325 816-818. ... 

McMahon In terms of the model you are presenting that H19 might have a functional role, what has been done with regard to gene targeting to remove the H19 transcriptional locus or to ectopically express it in transgenics ... 

Epithelial cells express but do not apically localize Pins, and do not express Insc. We have previously shown that ectopically expressed Insc localizes to the apical cortex in wild-type epithelial cells (Kraut et al 1996). Interestingly, ectopic Insc expression causes Pins, which is normally localized to the lateral cortex, to localize to the apical cortex. Conversely, apical localization of ectopically expressed Insc is dependent on pins. Insc ectopically expressed in Pins- epithelial cells does not localize as an apical crescent it adopts a cytoplasmic distribution which is enriched towards the apical side of the cell during interphase and is undetectable during mitosis, presumably due to rapid degradation. This instability of ectopically expressed Insc may be why the 90° rotation in the mitotic spindles which occurs as a consequence of Insc ectopic expression in the wild-type epithelial cells no longer occurs when Insc is expressed in Pins-embryos. These results indicate that Insc is necessary and sufficient for the recruitment of Pins to the apical cortex of wild-type epithelial cells. 

Schaar In the epithelial cells that don t normally express Insc, does ectopic expression of Insc not only result in relocalization of Pins but also reorientation of the spindle ... 

Karim FD, Rubin GM 1998 Ectopic expression of activated Rasl induces hyperplastic growth and increased cell death in Drosophila imaginal tissues. Development 125 1-9 Kawamura K, Shibata T, Saget O, Peel D, Bryant PJ 1999 A new family of growth factors produced by the fat body and active on Drosophila imaginal disc cells. Development 126 211-219... 

Bryant Not as far as I know. We have started ectopic expression studies. When we express them in imaginal discs they don t show a growth phenotype. They don t seem to be acting on a local level in this way. 

Bryant There are no mutants in Cbl but it has been tested in an ectopic expression assay, and if it is expressed in the eye disc it interferes with photoreceptor cell development (Meisner et al 1997). 

Thompson, A. J., A. C. Jackson et al. (2000b). Ectopic expression of a tomato 9-cw-epoxycarotcnoid dioxygenase gene causes over-production of abscisic acid. Plant J. 23(3) 363-374. 

Rao, S.S., Chu, C. and Kohtz, D.S. (1994) Ectopic expression of cyclin D1 prevents activation of gene transcription by myogenic basic helix-loop-helix regulators. Molecular and Cellular Biology 14, 5259—5267. 

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