Functional disruption of IEX‐1 expression by concatemeric hammerhead ribozymes alters growth properties of 293 cells

Grobe, Olaf; Arlt, Alexander; Ungefroren, Hendrik; Krupp, Guido; Fölsch, Ulrich R.; Schmidt, Wolfgang E.; Schäfer, Heiner

doi:10.1016/s0014-5793(01)02344-4

Cited by 35 publications

(56 citation statements)

References 25 publications

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“…IEX-1 as well as its rodent homologues PRG1 and gly96 represent short-lived proteins consisting of 156, 160 and 153 amino acids, respectively, and, to current knowledge, share no significant sequence similarities with any other known protein. Depending on cell type and stimulus-specific conditions, IEX-1 regulates cell growth and cellular viability (reviewed in Wu, 2003), and a significant apoptosis triggering effect by IEX-1 has been described (Scha¨fer et al, 1999;Arlt et al, 2001;Grobe et al, 2001;Schilling et al, 2001;Osawa et al, 2003;Shen et al, 2006). In the present study, we identified IEX-1 as an important mediator of G17-dependent NFkB inhibition and apoptosis in Colo320 cells expressing the wild-type CCK2 receptor.…”

Section: Introductionsupporting

confidence: 51%

The apoptosis-inducing effect of gastrin on colorectal cancer cells relates to an increased IEX-1 expression mediating NF-κB inhibition

et al. 2007

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Addressing the puzzling role of amidated gastrin 17 (G17) and the gastrin/CCKB/CCK2 receptor in colorectal carcinogenesis, we analysed potential candidate genes involved in G17-dependent NF-jB inhibition and apoptosis. The colorectal carcinoma cell line Colo320 overexpressing the wild-type CCK2 receptor (Colo320wt) underwent G17-induced apoptosis along with suppressed NF-jB activation and decreased expression of the antiapoptotic NF-jB target genes cIAP1 and cIAP2, whereas G17 was without effect on Colo320 cells expressing a CCK2 receptor bearing a loss of function mutation (Colo320mut). Gene microarray analysis revealed an elevated expression of the stress response gene IEX-1 in G17-treated Colo320wt but not Colo320mut cells. Quantitative real-time PCR and conventional RT-PCR confirmed this G17-dependent increase of IEX-1 expression in Colo320wt cells. If these cells were subjected to IEX-1 knockdown by small interfering RNA transfection, the apoptosis-inducing effect of G17 was abolished. Moreover, tumor necrosis factor alpha (TNFa)-or 5-FUinduced apoptosis that is greatly enhanced by G17 treatment in Colo320wt cells was prevented if IEX-1 expression was repressed. Under these conditions of blocked IEX-1 expression, the NF-jB activity remained unaffected by G17, in particular in Colo320wt cells co-treated with TNFa and also the suppressive effect of G17 on cIAP1 and cIAP2 expression was not observed anymore if IEX-1 expression was blocked. Conversely, IEX-1 overexpression in Colo320mut cells caused an increase of basal and TNFa-or 5-FU-induced apoptosis, an effect not further triggered by G17 treatment. Using a xenograft tumor model in severe combined immune deficiency mice, we could show that experimental systemic hypergastrinemia induced by the administration of omeprazole led to enhanced apoptosis as well as to a marked increase of IEX-1 expression in Colo320wt tumors, but not in Colo320mut tumors. These observations indicate that the proapoptotic effect of G17 on human colon cancer cells expressing the wild-type CCK2 receptor is mediated by IEX-1, which modulates NF-jB-dependent antiapoptotic protection and thereby exerts tumor-suppressive potential.

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Section: Introductionsupporting

confidence: 51%

The apoptosis-inducing effect of gastrin on colorectal cancer cells relates to an increased IEX-1 expression mediating NF-κB inhibition

et al. 2007

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“…IEX-1L antideath protein has been recognized as an apoptosis inhibitor involved in NF-B-mediated cell survival (15,16). In contrast, a proapoptotic role of IEX-1 has also been presented (17)(18)(19). Thus, the role of IEX-1 in apoptotic signaling remains controversial.…”

Section: Expression Profiling Of Tnf-␣-modulated Nf-b-dependent Genesmentioning

confidence: 99%

“…Among several NF-B-dependent genes, we focused on x-ray-inducible immediate early response factor-1 (IEX-1), which is a unique immediate-early gene that was initially identified following exposure of human squamous carcinoma cells to X-irradiation (14). Recent studies indicate that IEX-1 is implicated in apoptotic signaling and cell cycle control (15)(16)(17)(18)(19)(20)(21)(22). However, IEX-1 appears to exert apparently contradictory effects, depending on the type of cells, stimuli, and its expressed forms.…”

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confidence: 99%

“…However, IEX-1 appears to exert apparently contradictory effects, depending on the type of cells, stimuli, and its expressed forms. For example, the longer IEX-1 transcript with 37 amino acid insertion, called IEX-1L, is regarded as an apoptosis inhibitor in NF-B-mediated cell survival (15,16), whereas IEX-1S, a shorter original IEX-1 transcript promotes apoptosis (17,18,19). Interestingly, it has been proposed by two independent investigators that IEX-1S may promote cell proliferation under favorable growth conditions but facilitate apoptosis under unfavorable conditions (17,18).…”

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Expression of the NF-κB Target Gene X-Ray-Inducible Immediate Early Response Factor-1 Short Enhances TNF-α-Induced Hepatocyte Apoptosis by Inhibiting Akt Activation

Osawa

Nagaki

Banno

et al. 2003

The Journal of Immunology

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Using a cDNA microarray analysis, we identified x-ray-inducible immediate early response factor-1 (IEX-1) as a proapoptotic gene which was induced by TNF-α and also depend on NF-κB activation in Hc human hepatocytes. In these cells only the original form of IEX-1, termed IEX-1S, but not its longer transcript IEX-1L, was expressed. Overexpression of IEX-1S resulted in promotion of TNF-α-induced apoptosis in Hc cells expressing a mutant form of IκB. This proapoptotic action can be explained by its inhibitory findings on survival signals; inhibition of TNF-α-induced activation and expression of phosphatidylinositol 3-kinase (PI3K)/Akt, and also blockage of expression of Mcl-1, an antiapoptotic Bcl-2 family member which is located downstream of Akt, was inhibited by IEX-1S. LY 294002, an inhibitor of PI3K, increased IEX-1S expression induced by TNF-α and accelerated TNF-α-induced apoptosis in IκB-treated Hc cells. Overexpression of the dominant-negative Akt enhanced, but the constitutively active Akt suppressed, TNF-α-induced IEX-1S expression, suggesting that PI3K/Akt negatively regulated IEX-1S expression. These results demonstrate that NF-κB-dependent recruitment of IEX-1S may play a proapoptotic role in TNF-α-stimulated hepatocytes through blockage of the PI3K/Akt pathway. Moreover, the reciprocal cross-talk between IEX-1S and PI3K/Akt may closely be involved in the regulation of TNF-α-induced hepatocyte apoptosis.

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“…The human immediate early gene X-1 (IEX-1, also known as Dif2, and murine orthologs gly96 and PRG1) plays a role in the control of apoptosis and cellular growth [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The gene (gly96) was initially identified in mouse fibroblasts as a serum-regulated, glycosylated, immediate early gene [1].…”

Section: Introductionmentioning

confidence: 99%

Immediate early gene X-1 interacts with proteins that modulate apoptosis

Kumar¹,

Lutz²,

Frank³

et al. 2004

Biochemical and Biophysical Research Communications

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Immediate early gene X-1 (IEX-1) modulates apoptosis, cellular growth, mechanical strain-induced cardiac hypertrophy, and vascular intimal hyperplasia. To determine how IEX-1 alters apoptosis, we performed yeast two-hybrid studies using IEX-1 as the "bait" protein, and examined interactions between IEX-1 and proteins expressed by a human kidney cDNA expression library. We found that IEX-1 interacts with several proteins of which at least four are known to play a role in the regulation of apoptosis: (1) calcium-modulating cyclophilin ligand; (2) tumor necrosis factor-related apoptosisinducing ligand (tumor necrosis factor superfamily, member 10); (3) ML-1 myeloid cell leukemia gene encoded protein; and (4) BAT3, a gene present in the major histo-compatibility complex. Our data suggest that IEX-1 may regulate apoptosis by directly interacting with various proteins involved in the control of apoptotic pathways. KeywordsIEX-1; gly96; 1,25-Dihydroxyvitamin D; ApoptosisThe human immediate early gene X-1 (IEX-1, also known as Dif2, and murine orthologs gly96 and PRG1) plays a role in the control of apoptosis and cellular growth [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The gene (gly96) was initially identified in mouse fibroblasts as a serum-regulated, glycosylated, immediate early gene [1]. The messenger RNA of a similar gene (p22/PRG1) is induced in rat pancreatic cells by pituitary adenylate cyclase activating peptide (PACAP) [20]. The human ortholog of gly96 and PRG1, IEX-1, was identified as an X-radiation induced in fibroblasts by Kondratyev et al. [2], and as a UV-radiation and 1α, 25-dihydroxyvitamin D 3 -regulated gene in human keratinocytes [3,4].Increased expression of IEX-1 is associated with an increase in the growth rate of keratinocytes and HeLa cells, and disruption of IEX-1 gene expression in HeLa cells and 293 cells is associated with a decrease in cellular proliferation [3,7,8,21]. IEX-1 has been shown to be induced in cardiomyocytes and vascular smooth muscle cells by mechanical stretch, and overexpression of IEX-1 in vascular smooth muscle cells protects against stretch-induced hypertrophy [9,15] IEX-1 is regulated by a variety of factors. IEX-1 expression is increased by serum, X-, and UV-irradiation, growth factors such as epidermal growth factor, inflammatory stimuli such as lipopolysaccharide and ceramide, retinoids such as all-trans-retinoic acid or cis-retinoic acid, and by over-expression of Sp1 in cells [1][2][3]6,10,11,20,[24][25][26][27][28][29][30][31]. The gene is repressed by steroid hormones such as 1α, 25-dihydroxyvitamin D 3 and by over-expression of p53 [3,4,30,32]. 1α, 25-Dihydroxyvitamin D 3 also results in a redistribution of IEX-1 from the nucleus into the peri-nuclear and cytoplasmic space. The ratio of Sp1 to p53 within the cell appears to regulate the amount of IEX-1 expression present within the cell [30]. Slight modifications of IEX-1 transcription are observed by mutating putative elements for p300, Sox, NFκB, and AP4 within the prom...

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Functional disruption of IEX‐1 expression by concatemeric hammerhead ribozymes alters growth properties of 293 cells

Cited by 35 publications

References 25 publications

The apoptosis-inducing effect of gastrin on colorectal cancer cells relates to an increased IEX-1 expression mediating NF-κB inhibition

The apoptosis-inducing effect of gastrin on colorectal cancer cells relates to an increased IEX-1 expression mediating NF-κB inhibition

Expression of the NF-κB Target Gene X-Ray-Inducible Immediate Early Response Factor-1 Short Enhances TNF-α-Induced Hepatocyte Apoptosis by Inhibiting Akt Activation

Immediate early gene X-1 interacts with proteins that modulate apoptosis

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