Epigenetic Effects on Transgene Expression

Whitelaw, Emma; Sutherland, Heidi G.; Kearns, Margot; Morgan, Hugh D.; Weaving, Linda S.; Garrick, David

doi:10.1385/1-59259-220-1:351

Cited by 26 publications

(26 citation statements)

References 82 publications

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“…The reason for this variability in expression is unclear, but it needs to be accounted for when one is using both of these transgenic lines. It is well known that epigenetic silencing can suppress transgene expression over time (30). It is also possible that the incomplete expression of our CA-Rac1 transgene is related to other epigenetic factors that affect the expression of both the rtTA and EGFP_CA-Rac1 transgenes.…”

Section: Discussionmentioning

confidence: 99%

Rac1 Activation in Podocytes Induces Rapid Foot Process Effacement and Proteinuria

Suleiman

Kim

et al. 2013

Molecular and Cellular Biology

108

112

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The kidney's vital filtration function depends on the structural integrity of the glomerulus, the proximal portion of the nephron. Within the glomerulus, the architecturally complex podocyte forms the final cellular barrier to filtration. Injury to the podocyte results in a morphological change called foot process effacement, which is a ubiquitous feature of proteinuric diseases. The exact mechanism underlying foot process effacement is not known, but recently it has been proposed that this change might reflect activation of the Rac1 GTPase. To test this hypothesis, we generated a podocyte-specific, inducible transgenic mouse line that expressed constitutively active Rac1. When the Rac1 transgene was induced, we observed a rapid onset of proteinuria with focal foot process effacement. Using superresolution imaging, we verified that the induced transgene was expressed in damaged podocytes with altered foot process morphology. This work sheds new light on the complex balance of Rho GTPase signaling that is required for proper regulation of the podocyte cytoskeleton.

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Section: Discussionmentioning

confidence: 99%

Rac1 Activation in Podocytes Induces Rapid Foot Process Effacement and Proteinuria

Suleiman

Kim

et al. 2013

Molecular and Cellular Biology

108

112

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“…Although DNA methylation and silencing of transgenes are common in transgenic mice, DNA methylation-associated inactivation of interstitial transgenes generally exhibits mosaicism, the frequency of which depends on the integration site and the nature of the integrated sequences (56). The absence of mosaicism in the methylation and expression of the telomeric transgenes therefore shows that silencing at telomeres is exceptionally efficient.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the repression of some interstitial integration sites containing telomeric repeat sequences appears to be mediated, at least partially, through type I and/or II histone deacetylases. This variation in the mechanism of repression for transgenes at interstitial sites containing telomeric repeat sequences may result from differences in the cellular DNA surrounding the integration sites, which has previously been shown to influence the silencing of transgenes in mammalian cells (56).…”

Section: Fig 1 Generation and Characterization Of Es Cell Clones Fomentioning

confidence: 99%

Telomere Position Effect and Silencing of Transgenes near Telomeres in the Mouse

Pedram

Sprung

Gao

et al. 2006

Molecular and Cellular Biology

118

107

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Reversible transcriptional silencing of genes located near telomeres, termed the telomere position effect (TPE), is well characterized in Saccharomyces cerevisiae. TPE has also been observed in human tumor cell lines, but its function remains unknown. To investigate TPE in normal mammalian cells, we developed clones of mouse embryonic stem (ES) cells that contain single-copy marker genes integrated adjacent to different telomeres. Analysis of these telomeric transgenes demonstrated that they were expressed at very low levels compared to the same transgenes integrated at interstitial sites. Similar to the situation in yeast, but in contrast to studies with human tumor cell lines, TPE in mouse ES cells was not reversed with trichostatin A. Prolonged culturing without selection resulted in extensive DNA methylation and complete silencing of telomeric transgenes, which could be reversed by treatment with 5-azacytidine. Thus, complete silencing of the telomeric transgenes appears to involve a two-step process in which the initial repression is reinforced by DNA methylation. Extensive methylation of the telomeric transgenes was also observed in various tissues and embryonic fibroblasts isolated from transgenic mice. In contrast, telomeric transgenes were not silenced in ES cell lines isolated from 3-day-old preimplantation embryos, consistent with the hypothesis that TPE plays a role in the development of the embryo.

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“…We tested a variety of acute actions of ethanol, with an emphasis on those that might be related to spinal cord or motor control. To ensure that behavioral phenotypes were not due to the integration site, which will vary among transgenic lines (Whitelaw et al, 2001), we constructed and compared multiple independent lines of transgenic mice.…”

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confidence: 99%

Transgenic Expression of a Mutant Glycine Receptor Decreases Alcohol Sensitivity of Mice

Findlay¹,

Wick²,

Mascia³

et al. 2002

J Pharmacol Exp Ther

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Glycine receptors (GlyRs) are pentameric ligand-gated ion channels that inhibit neurotransmission in the adult brainstem and spinal cord. GlyR function is potentiated by ethanol in vitro, and a mutant GlyR subunit ␣ 1 (S267Q) is insensitive to the potentiating effects of ethanol. To test the importance of GlyR for the actions of ethanol in vivo, we constructed transgenic mice with this mutation. Under the control of synapsin I regulatory sequences, transgenic expression of S267Q mutant GlyR ␣ 1 subunits in the nervous system was demonstrated using [ 3 H]strychnine binding and immunoblotting. These mice showed decreased sensitivity to ethanol in three behavioral tests: ethanol inhibition of strychnine seizures, motor incoordination (rotarod), and loss of righting reflex. There was no change in ethanol sensitivity in tests of acute functional tolerance or body temperature, and there was no change in ethanol metabolism. Transgene effects were pharmacologically specific for ethanol, compared with pentobarbital, flurazepam, and ketamine. These results support the idea that glycine receptors contribute to some behavioral actions of ethanol and that ethanol sensitivity can be changed in vivo by transgenic expression of a single receptor subunit.

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Epigenetic Effects on Transgene Expression

Cited by 26 publications

References 82 publications

Rac1 Activation in Podocytes Induces Rapid Foot Process Effacement and Proteinuria

Rac1 Activation in Podocytes Induces Rapid Foot Process Effacement and Proteinuria

Telomere Position Effect and Silencing of Transgenes near Telomeres in the Mouse

Transgenic Expression of a Mutant Glycine Receptor Decreases Alcohol Sensitivity of Mice

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