Identification of two novel members of<i>erbA</i>superfamily by molecular cloning: the gene products of the two are highly related to each other

Miyajtma, Nobuyuki; Kandowaki, Yasunori; Fukushige, S.; Shimizu, Seiichiro; Semba, Kentaro; Yamanashi, Yuji; Matsubara, K; Toyoshima, Kumao; Yamamoto, Tadashi

doi:10.1093/nar/16.23.11057

Cited by 211 publications

(102 citation statements)

References 39 publications

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“…The first half-repeat is identical and the second very homologous to the consensus half-repeat site 5Ј-AG(G/T)TCA-3Ј of the HREs (39 -41). DNA-binding gel electrophoresis assays using extracts of COS-1 cells transiently transfected with plasmids expressing HNF-4, ARP-1 (COUP-TFII), or EAR-2 (COUP-TFI) (18,42) showed that oligonucleotide CIIC binds ARP-1 and EAR-2 but does not bind HNF-4, indicating that the region defined by footprint CIIC is an important regulatory element.…”

Section: Discussionmentioning

confidence: 99%

A Short Proximal Promoter and the Distal Hepatic Control Region-1 (HCR-1) Contribute to the Liver Specificity of the Human Apolipoprotein C-II Gene

Vorgia

Zannis

Kardassis

1998

Journal of Biological Chemistry

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We have identified the regulatory elements, some of the factors and potential regulatory mechanisms which determine the tissue specificity of the human apoC-II gene. The ؊545/؉18 apoC-II promoter directs high levels of expression of the reporter CAT gene in cells of hepatic origin (HepG2), low levels of expression in cells of intestinal origin (CaCo-2) and basal expression in HeLa cells. Deletion analysis identified negative regulatory elements within the ؊545/؊388 region and positive regulatory elements within the ؊388/؊55 region. Linkage of different apoC-II promoter segments to the hepatic control region-1 (HCR-1) enhanced the promoter activity 2.5-11-fold in HepG2 cells but did not affect its activity in CaCo-2 or COS-1 cells. DNase I footprinting analysis using rat liver nuclear extracts identified five protected regions within the ؊545/؉18 apoC-II promoter as follows: CIIA (؊74/؊44), CIIB (؊102/؊81), CIIC (؊159/؊116), CIID (؊288/؊265), and CIIE (؊497/؊462). Elements CIIB and CIIC contain hormone response elements. CIIB is recognized by hepatic nuclear factor-4 (HNF-4) but not ARP-1 or EAR-2, whereas CIIC is recognized by ARP-1 and EAR-2 but not by HNF-4. HNF-4 transactivated the apoC-II promoter or the apoC-II promoter linked to the HCR-1 in COS-1 cells. A double mutation in elements CIIB and CIIC that eliminated binding of HNF-4 or ARP-1 and EAR-2, respectively, to these sites abolished the enhancer activity of HCR-1. The combined data suggest that the apoC-II promoter/HCR-1 cluster can direct expression in cells of hepatic origin and that optimal enhancer activity requires synergistic interactions between factors bound to the distal HCR-1 and nuclear receptors bound to the two proximal hormone response elements. Plasma apolipoprotein CII (apoC-II)1 is a 79-amino acid protein that plays an important role in the catabolism of triglyceride-rich lipoproteins (1, 2). ApoC-II is a potent activator of the lipoprotein lipase, the enzyme that hydrolyzes the triglycerides of chylomicrons and very low density lipoproteins (3, 4). Patients with inherited apoC-II deficiency are unable to clear triglyceride-rich lipoprotein particles from their plasma, and develop type I hyperlipidemia (2, 5, 6). The human apoC-II gene has been mapped on the long arm of chromosome 19 in a gene cluster that contains the apoE/CI/CIЈ/CIV/CII genes and spans 45 kb of chromosomal region (7-9). The intergenic region between the apoC-II and apoC-IV genes is only 0.55 kb (1). The major site of apoC-II mRNA and protein synthesis in mammalian species is the liver and a minor site is the intestine (10 -12). Studies using transgenic mice have provided evidence for the existence of common regulatory regions within the 45 kb that control the tissue-specific expression of the apoC-I and apoE genes (13-15). These regions were designated hepatic control region-1 and -2 (HCR-1 and HCR-2), respectively (13,14).The objective of the current study was to identify the promoter elements which confer tissue specificity and assess the potential role of HCR-1 i...

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Section: Discussionmentioning

confidence: 99%

A Short Proximal Promoter and the Distal Hepatic Control Region-1 (HCR-1) Contribute to the Liver Specificity of the Human Apolipoprotein C-II Gene

Vorgia

Zannis

Kardassis

1998

Journal of Biological Chemistry

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“…Unexpectedly, we isolated an ear2 sequence in a cDNA library screen that, when linked in frame to remnants of a gag sequence of the Moloney murine leukemia virus, exhibited resistance to TGF-␤-induced cell-growth inhibition (data not shown). The nuclear orphan receptor, ear2 (erbA related gene 2), is a member of the COUP-TF (NR2) subfamily of nuclear hormone receptors and shares homology with TR␣ (Miyajima et al, 1988). Whereas gag-ear2 fusion is artificially created during the construction of cDNA library, fusion proteins between a viral gag sequence and nuclear hormone receptors have been identified in nature (Grignani et al, 1998;Lin and Evans, 2000;La et al, 2003).…”

Section: V-erba Expression Dysregulates Tgf-␤ Signalingmentioning

confidence: 99%

“…We were prompted to test whether v-ErbA might disrupt TGF-␤ signal transduction activity when we isolated an ear2 sequence in a cDNA library screen that, when linked in frame to remnants of a gag sequence of the Moloney murine leukemia virus, exhibited resistance to TGF-␤-induced cell-growth inhibition. The nuclear orphan receptor, ear2 (erbA related gene 2), is a member of the COUP-TF (NR2) subfamily of nuclear hormone receptors and shares homology with TR␣ (Miyajima et al, 1988). Using retroviral gene-mediated transfer, the full-length coding sequence of v-ErbA with a C-terminal-Flag-tag was stably expressed in the mink lung epithelial cell line (PE25) that was previously modified to express an ectopic receptor and the TGF-␤-responsive PE2.1 luciferase reporter gene (Liu et al, 1997;Hua et al, 1998).…”

Section: V-erba Expression Dysregulates Tgf-␤ Signalingmentioning

confidence: 99%

Association of v-ErbA with Smad4 Disrupts TGF-β Signaling

Erickson

Liu

2009

MBoC

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Disruption of the transforming growth factor-␤ (TGF-␤) pathway is observed in the majority of cancers. To further understand TGF-␤ pathway inactivation in cancer, we stably expressed the v-ErbA oncoprotein in TGF-␤ responsive cells. v-ErbA participates in erythroleukemic transformation of cells induced by the avian erythroblastosis virus (AEV).Here we demonstrate that expression of v-ErbA was sufficient to antagonize TGF-␤-induced cell growth inhibition and that dysregulation of TGF-␤ signaling required that v-ErbA associate with the Smad4 which sequesters Smad4 in the cytoplasm. We also show that AEV-transformed erythroleukemia cells were resistant to TGF-␤-induced growth inhibition and that TGF-␤ sensitivity could be recovered by reducing v-ErbA expression. Our results reveal a novel mechanism for oncogenic disruption of TGF-␤ signaling and provide a mechanistic explanation of v-ErbA activity in AEV-induced erythroleukemia. INTRODUCTIONThe transforming growth factor-␤ (TGF-␤) signaling pathway is a major signaling network that controls cell proliferation, differentiation, and tumor suppression (Massague et al., 2000;Attisano and Wrana, 2002;Wakefield and Roberts, 2002). The TGF-␤ cytokine signals through hetero-oligomeric complexes of type I and type II serine/threonine kinase receptors, TGF-␤ type I (T␤RI) and type II (T␤RII) receptors (Heldin et al., 1997;Massague et al., 2000). On ligand binding to the T␤RII receptor, T␤RII phosphorylates T␤RI and activates the Tß␤RI kinase (Wrana et al., 1992;Chen and Weinberg, 1995). The signal is further propagated by phosphorylation of the downstream signal transducers Smad2 and Smad3 by the type I receptor kinase (Heldin et al., 1997). Phosphorylated Smad2 and Smad3 form a complex with Smad4 and translocate into the nucleus (Massague et al., 2000). These Smad complexes then interact with other transcription factors and bind the promoter regions of TGF-␤-responsive genes to regulate gene expression (Massague et al., 2000).Insensitivity to antigrowth signals such as TGF-␤ is common in cancer cells (Hanahan and Weinberg, 2000;Massague et al., 2000). Multiple genetic mutations are observed in TGF-␤-insensitive tumor cells, and mechanisms have been identified that explain the disruption of TGF-␤'s cytostatic activity. These mechanisms include the down-regulation of TGF-␤ receptors, mutations in TGF-␤ signaling components such as Smad4, and mutations in other downstream targets (Hanahan and Weinberg, 2000;Massague et al., 2000). Overexpression of oncoproteins is also implicated in the disruption of TGF-␤ signaling. Tumor cells insensitive to TGF-␤ are known to overexpress diverse oncoproteins such as Cdk4, Ski, Evi-1, Ras, Mdm2, E6/E7, E1A, and PLZF-RAR␣ (Pietenpol et al., 1990;Ewen et al., 1993;Datto et al., 1997;Kurokawa et al., 1998;Sun et al., 1998;Hanahan and Weinberg, 2000;Massague et al., 2000;La et al., 2003;Luo, 2004). Overexpression of HPV-16 E7 and E1A, for example, is shown to cause TGF-␤ resistance in skin keratinocytes by preventing TGF-␤-induced down-regulatio...

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“…The latter result suggests that the repression by EAR3/COUP-TF1 involves specific competition with HNF-4 for binding to the Epo gene. Since EAR3/COUP-TF1 and ARP-1/COUP-TF2 receptors are expressed in a broad variety of tissues and EAR2 is expressed primarily in the liver (33), it is likely that one or more of the COUP family members modulate the expression of Epo in vivo. As yet we have no evidence that EAR3/COUP-TF1 is a more likely contributor than other COUP family members.…”

Section: Fig 4 An Ear3/coup-tf1-related Factor From Hep3b Nuclear Ementioning

confidence: 99%

The Orphan Receptor Hepatic Nuclear Factor 4 Functions as a Transcriptional Activator for Tissue-Specific and Hypoxia-Specific Erythropoietin Gene Expression and Is Antagonized by EAR3/COUP-TF1

Galson

Tsuchiya

Tendler

et al. 1995

Molecular and Cellular Biology

187

138

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The erythropoietin (Epo) gene is regulated by hypoxia-inducible cis-acting elements in the promoter and in a 3 enhancer, both of which contain consensus hexanucleotide hormone receptor response elements which are important for function. A group of 11 orphan nuclear receptors, transcribed and translated in vitro, were screened by the electrophoretic mobility shift assay. Of these, hepatic nuclear factor 4 (HNF-4), TR2-11, ROR␣1, and EAR3/COUP-TF1 bound specifically to the response elements in the Epo promoter and enhancer and, except for ROR␣1, formed DNA-protein complexes that had mobilities similar to those observed in nuclear extracts of the Epo-producing cell line Hep3B. Moreover, both anti-HNF-4 and anti-COUP antibodies were able to supershift complexes in Hep3B nuclear extracts. Like Epo, HNF-4 is expressed in kidney, liver, and

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Identification of two novel members oferbAsuperfamily by molecular cloning: the gene products of the two are highly related to each other

Cited by 211 publications

References 39 publications

A Short Proximal Promoter and the Distal Hepatic Control Region-1 (HCR-1) Contribute to the Liver Specificity of the Human Apolipoprotein C-II Gene

A Short Proximal Promoter and the Distal Hepatic Control Region-1 (HCR-1) Contribute to the Liver Specificity of the Human Apolipoprotein C-II Gene

Association of v-ErbA with Smad4 Disrupts TGF-β Signaling

The Orphan Receptor Hepatic Nuclear Factor 4 Functions as a Transcriptional Activator for Tissue-Specific and Hypoxia-Specific Erythropoietin Gene Expression and Is Antagonized by EAR3/COUP-TF1

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