Mouse TonEBP-NFAT5: expression in early development and alternative splicing

Maouyo, Djikolngar; Kim, Jee Y.; Lee, Sang-Deok; Wu, Yanhong; Woo, Seung Kyoon; Kwon, Hyug Moo

doi:10.1152/ajprenal.00123.2001

Cited by 52 publications

(51 citation statements)

References 18 publications

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“…Remarkably, the depletion of ddx5 and ddx17 did not affect the total NFAT5 mRNA level in any of the tested cell lines (Figure 4c). However, RT-PCR using primers in exons 3 and 6 that flank known alternative exons 4 and 5 (Dalski et al, 2002;Maouyo et al, 2002) revealed that ddx5/ ddx17 depletion in MDA-MB-231, HeLa and MCF-7 cells favored the shorter NFAT5 product that did not contain exons 4 and 5 (E3/E6, Figure 4d). This result was further supported after sequencing the PCR products (not shown) and by quantifying NFAT5 splicing variants by RT-Quantitative (q)PCR.…”

Section: Nfat5 Ddx17mentioning

confidence: 99%

Dual role of the ddx5/ddx17 RNA helicases in the control of the pro-migratory NFAT5 transcription factor

et al. 2012

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Ddx5 and ddx17 are two highly related RNA helicases involved in both transcription and splicing. These proteins coactivate transcription factors involved in cancer such as the estrogen receptor alpha, p53 and beta-catenin. Ddx5 and ddx17 are part of the splicing machinery and can modulate alternative splicing, the main mechanism increasing the proteome diversity. Alternative splicing also has a role in gene expression level regulation when it is coupled to the nonsensemediated mRNA decay (NMD) pathway. In this work, we report that ddx5 and ddx17 have a dual role in the control of the pro-migratory NFAT5 transcription factor. First, ddx5 and ddx17 act as transcriptional coactivators of NFAT5 and are required for activating NFAT5 target genes involved in tumor cell migration. Second, at the splicing level, ddx5 and ddx17 increase the inclusion of NFAT5 exon 5. As exon 5 contains a pre-mature translation termination codon, its inclusion leads to the regulation of NFAT5 mRNAs by the NMD pathway and to a decrease in NFAT5 protein level. Therefore, we demonstrated for the first time that a transcriptional coregulator can simultaneously regulate the transcriptional activity and alternative splicing of a transcription factor. This dual regulation, where ddx5 and ddx17 enhance the transcriptional activity of NFAT5 although reducing its protein expression level, suggests a critical role for ddx5 and ddx17 in tumor cell migration through the fine regulation of NFAT5 pathway.

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Section: Nfat5 Ddx17mentioning

confidence: 99%

Dual role of the ddx5/ddx17 RNA helicases in the control of the pro-migratory NFAT5 transcription factor

et al. 2012

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“…First, NFAT5 RNA expression is not limited to the kidney, but is in fact ubiquitous (10,15,18). Analysis of protein expression further indicates that NFAT5 is expressed in essentially all tissues of the developing embryo, with particularly high levels of expression in the brain and heart (19). In adult tissues detectable NFAT5 protein is limited to the thymus and mitogen-activated primary T lymphocytes (15).…”

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confidence: 99%

The Osmoprotective Function of the NFAT5 Transcription Factor in T Cell Development and Activation

Trama

2002

The Journal of Immunology

105

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The NFAT5/TonEBP transcription factor, a recently identified rel/NF-κB family member, activates transcription of osmocompensatory genes in response to extracellular hyperosmotic stress. However, the function of NFAT5 under isosmotic conditions present in vivo remains unknown. Here we demonstrate that NFAT5 is necessary for optimal T cell development in vivo and allows for optimal cell growth ex vivo under conditions associated with osmotic stress. Transgenic mice expressing an inhibitory form of NFAT5 in developing and mature T cells exhibited a 30% reduction in thymic cellularity evenly distributed among thymic subsets, consistent with the uniform expression and nuclear localization of NFAT5 in each subset. This was associated with a 25% reduction in peripheral CD4+ T cells and a 50% reduction in CD8+ T cells. While transgenic T cells exhibited no impairment in cell growth or cytokine production under normal culture conditions, impaired cell growth was observed under both hyperosmotic conditions and isosmotic conditions associated with osmotic stress. Transgenic thymocytes also demonstrated increased sensitivity to osmotic stress. Consistent with this, the system A amino acid transporter gene ATA2 exhibited NFAT5 dependence under hypertonic conditions but not in response to amino acid deprivation. Expression of the TNF-α gene, a putative NFAT5 target, was not altered in transgenic T cells. These results not only demonstrate an osmoprotective function for NFAT5 in primary cells but also show that NFAT5 is necessary for optimal thymic development in vivo, suggesting that developing thymocytes within the thymic microenvironment are subject to an osmotic stress that is effectively countered by NFAT5-dependent responses.

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“…NFAT5, the only known osmosensitive transcription factor, is expressed in many tissues bathed in either isotonic or hypertonic environment in vivo [12,15]. A genome database search reveals that Rel-like transcription factors are present in Drosophila and mammals but not in Caenorhabditis elegans, yeast, and plants [18].…”

Section: Discussionmentioning

confidence: 99%

“…NFAT5 is expressed not only in the renal medulla that is significantly hyperosmolar but also in the brain, thymus, liver, and many other tissues that are not in hypertonic milieu under physiological conditions [12,17]. However, its expression in hybridoma cells has not been reported before.…”

Section: Expression Of Nfat5 In Hybridoma Cells and Its Regulation Bymentioning

confidence: 99%

“…However, the expression of NFAT5 is not limited to the kidney, but in fact is ubiquitous. It is widely expressed during early development and in adulthood, and is found in the brain, heart, liver, and many other organs [12][13][14]. As the extremes of hypertonicity present within the renal medulla do not appear to exist in these tissues under physiological conditions, the function of NFAT5 may not be limited to regulating transcription in response to hypertonic stress.…”

Section: Introductionmentioning

confidence: 99%

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Downregulation of NFAT5 by RNA interference reduces monoclonal antibody productivity of hybridoma cells

Zou

Xie

2007

Cell Res

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Hybridoma cells display an increase in antibody productivity following exposure to hypertonic conditions. However, the underlying mechanism is not well understood. In the present study, we hypothesize that the nuclear factor of activated T cells 5 (NFAT5)/tonicity enhancer binding protein (TonEBP) functions to increase the antibody productivity of hybridoma cells. NFAT5 is an osmosensitive mammalian transcription factor. However, its ubiquitous expression in various organs that are not bathed in hypertonic milieu suggests that NFAT5 may also regulate cell growth and function under isotonic conditions. In this study, we examined the expression of NFAT5 in hybridoma cells by Western blot analysis, and found that it increased significantly in hypertonic medium. To further define the function of NFAT5 in hybridoma cells, RNA interference technique was used to downregulate the expression of NFAT5 in SGB-8 cells (a hybridoma cell line). In isotonic medium, antibody productivity of hybridoma cells was reduced by downregulation of NFAT5 while cell proliferation was not influenced. The results presented here demonstrate that NFAT5 not only plays an important role in osmotic stress response pathway in hybridoma cells but also is essential for optimal antibody productivity.

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Mouse TonEBP-NFAT5: expression in early development and alternative splicing

Cited by 52 publications

References 18 publications

Dual role of the ddx5/ddx17 RNA helicases in the control of the pro-migratory NFAT5 transcription factor

Dual role of the ddx5/ddx17 RNA helicases in the control of the pro-migratory NFAT5 transcription factor

The Osmoprotective Function of the NFAT5 Transcription Factor in T Cell Development and Activation

Downregulation of NFAT5 by RNA interference reduces monoclonal antibody productivity of hybridoma cells

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