Biomedical subjects

M R Green

Publications and source records attributed to M R Green.

At least 109 records · Page 6Linked to original sources

PubMed1997

Phase I trial of etoposide, carboplatin, and GM-CSF in extensive small-cell lung cancer: a Cancer and Leukemia Group B study (CALGB 8832).

The maximum tolerated dose (MTD) of etoposide and carboplatin without growth factor support was previously defined by Cancer and Leukemia Group B (CALGB) as 200 and 125 mg/m2/day x 3, respectively, given every 28 days to previously untreated patients who have extensive, small-cell lung cancer (SCLC). Myelosuppression was dose-limiting. The purpose of this phase I trial was to determine if granulocyte macrophage colony-stimulating factor (GM-CSF) support allows the dosage of the combination of etoposide and carboplatin to be increased above the previously determined MTD. In this CALGB study of 44 evaluable patients with performance status 0-2, cohorts were treated with etoposide and carboplatin given intravenously on days 1-3 followed by GM-CSF (molgramostim) given subcutaneously on days 4-18. Four dose levels of bacteria-derived recombinant GM-CSF (5, 10, 20 microg/kg/day and 5 microg/kg every 12 h), three dose levels of etoposide (200, 250, and 300 mg/m2/day x 3), and two dose levels of carboplatin (125 and 150 mg/m2/day x 3) were evaluated. There was no chemotherapy dose escalation in individual patients. With 5 microg/kg/d GM-CSF, the first etoposide and carboplatin cycle of 300 and 150 mg/m2/day x 3, respectively, could be administered with acceptable toxicity. However, GM-CSF did not allow repeated administration of this dose-escalated regimen every 21 days, since delayed platelet and/or neutrophil recovery was dose limiting in later cycles. These results demonstrate that GM-CSF alone has limited capability to support the repeated administration of high doses of etoposide and carboplatin. CALGB currently is testing the ability of interleukin (IL)-6 given with GM-CSF to ameliorate the cumulative myelosuppression of this intense regimen.

Adult↗

PubMed1997

Randomized trial of chemotherapy and radiation therapy with or without warfarin for limited-stage small-cell lung cancer: a Cancer and Leukemia Group B study.

PURPOSE: Studies by the Veterans Administration Cooperative Studies Program and Cancer and Leukemia Group B (CALGB) suggested that the addition of warfarin to chemotherapy might enhance response and/or survival in small-cell lung cancer (SCLC). This randomized study evaluated the effect of warfarin with chemotherapy and radiation therapy in limited-stage SCLC. PATIENTS AND METHODS: Patients were randomized to receive warfarin or no warfarin. All patients received three cycles of doxorubicin, cyclophosphamide, and etoposide (ACE). Cycles 4 and 5 (cisplatin, cyclophosphamide, and etoposide [PCE]) were given concurrently with radiation therapy. Three cycles of ACE were given after chemoradiation therapy, but were discontinued due to a high rate of pulmonary toxicity. RESULTS: There were no significant differences in response rates, survival, failure-free survival, disease-free survival, or patterns of relapse between the warfarin-treated and control groups. In patients treated according to the initial design, an increase in failure-free survival seen with warfarin treatment approached significance (P = .07). Preamendment results, while not significant, did not have superimposable treatment survival curves. A landmark analysis at 8 months showed a median survival time after the landmark for complete responders of 33 months with warfarin treatment compared with < or = 13.75 months for complete or partial responders not treated with warfarin (P = .05). Differences between the complete responders in this preamendment population were not significant (P = .103). CONCLUSION: Warfarin does not appear to improve outcome significantly in limited-stage SCLC. However, the differences in some variables between populations before the protocol amendment correspond to the favorable effects of anticoagulants observed in previous studies.

Adult↗

PubMed1997

Improvements in survival and clinical benefit with gemcitabine as first-line therapy for patients with advanced pancreas cancer: a randomized trial.

PURPOSE: Most patients with advanced pancreas cancer experience pain and must limit their daily activities because of tumor-related symptoms. To date, no treatment has had a significant impact on the disease. In early studies with gemcitabine, patients with pancreas cancer experienced an improvement in disease-related symptoms. Based on those findings, a definitive trial was performed to assess the effectiveness of gemcitabine in patients with newly diagnosed advanced pancreas cancer. PATIENTS AND METHODS: One hundred twenty-six patients with advanced symptomatic pancreas cancer completed a lead-in period to characterize and stabilize pain and were randomized to receive either gemcitabine 1,000 mg/m2 weekly x 7 followed by 1 week of rest, then weekly x 3 every 4 weeks thereafter (63 patients), or to fluorouracil (5-FU) 600 mg/m2 once weekly (63 patients). The primary efficacy measure was clinical benefit response, which was a composite of measurements of pain (analgesic consumption and pain intensity), Karnofsky performance status, and weight. Clinical benefit required a sustained (> or = 4 weeks) improvement in at least one parameter without worsening in any others. Other measures of efficacy included response rate, time to progressive disease, and survival. RESULTS: Clinical benefit response was experienced by 23.8% of gemcitabine-treated patients compared with 4.8% of 5-FU-treated patients (P = .0022). The median survival durations were 5.65 and 4.41 months for gemcitabine-treated and 5-FU-treated patients, respectively (P = .0025). The survival rate at 12 months was 18% for gemcitabine patients and 2% for 5-FU patients. Treatment was well tolerated. CONCLUSION: This study demonstrates that gemcitabine is more effective than 5-FU in alleviation of some disease-related symptoms in patients with advanced, symptomatic pancreas cancer. Gemcitabine also confers a modest survival advantage over treatment with 5-FU.

Adult↗

PubMed1997

Investigations of new drugs in combination with cisplatin in stage III non-small cell lung cancer.

Chemotherapy has been shown to prolong the survival of patients with stage III non-small cell lung cancer. In particular, cisplatin and vinblastine administered before definitive radiotherapy results in a significant prolongation of median survival and increases the 2-year survival rate. Concomitant chemoradiotherapy also holds promise. Recently, several new active agents and combinations have been described for the treatment of stage III disease. The integration of these drugs and novel regimens into treatment plans for stage III non-small cell lung cancer is of great interest and a focus of current clinical investigations. Early data from these clinical trials are reviewed here.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Functional group substitutions of the branchpoint adenosine in a nuclear pre-mRNA and a group II intron.

Splicing of nuclear mRNA precursors (pre-mRNAs) takes place in the spliceosome, a large and complex ribonucleoprotein. Nuclear pre-mRNA splicing and group II intron self-splicing occur by a chemically identical pathway involving recognition of a specific branchpoint adenosine and nucleophilic activation of its 2'-hydroxyl group. The chemical similarity between these two splicing reactions, as well as other considerations, have suggested that the catalytic core of the spliceosome and group II introns may be related. Here we test this hypothesis by analyzing splicing and RNA branch formation of a pre-mRNA and a group II intron in which the branchpoint adenosine was substituted with purine base analogues. We find that replacement of the branchpoint adenosine with either of two modified adenosine analogues or guanosine leads to remarkably similar patterns of splicing and RNA branch formation in the two systems.

Adenosine↗

PubMed1997

A phase II study evaluating the efficacy of carboplatin, etoposide, and paclitaxel with granulocyte colony-stimulating factor in patients with stage IIIB and IV non-small cell lung cancer and extensive small cell lung cancer.

We initiated a phase II pilot study to determine whether adding paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) to combination carboplatin/etoposide is tolerable and active in patients with advanced non-small cell lung cancer and extensive small cell lung cancer. Patients were given carboplatin (area under the concentration-time curve of 6) followed by etoposide 80 to 100 mg/m2 intravenously on days 1 through 3 followed by paclitaxel 200 mg/m2 intravenously over 3 hours on day 3. On days 4 through 18, granulocyte colony-stimulating factor 5 microg/kg was administered subcutaneously. Each cycle was repeated every 21 days. Fourteen patients have been accrued to the study and 12 were evaluated for toxicity, the first 10 of whom were treated with 80 mg/m2 etoposide. Among the first 10 evaluable patients, significant grade 4 neutropenia occurred in one patient, grade 4 thrombocytopenia in three patients, grade 2 neuropathy in two patients, and grade 3 neurotoxicity in two patients. None of the four patients with non-small cell lung cancer responded to treatment, while six of seven small cell lung cancer patients have obtained major responses to therapy. We have increased the etoposide dose to 100 mg/m2 in subsequent patients. The combination chemotherapy regimen of carboplatin, etoposide, and paclitaxel is tolerable and active in patients with small cell lung cancer.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Pharmacology of 21-day oral etoposide given in combination with i.v. cisplatin in patients with extensive-stage small cell lung cancer: a cancer and leukemia group B study (CALGB 9062).

This was a pharmacological companion study to a randomized Phase III trial comparing 21-day oral versus 3-day i.v. etoposide in combination with i.v. cisplatin in patients with extensive-stage small cell lung cancer. Etoposide plasma concentrations were measured in patients randomized to the 21-day schedule and correlated with toxicity and tumor response. Patients were treated with etoposide (50 mg/m2/day) orally for 21 days and cisplatin (33 mg/m2/day) i.v. for 3 consecutive days every 28 days for 6 courses. Plasma samples before the daily etoposide dose (trough concentrations) and complete blood counts were obtained weekly during treatment. The average of three etoposide concentrations (EC) per course was calculated. Of 158 patients registered to this schedule of the study, 150 were eligible. In 106 patients, etoposide samples were obtained at least in the first course in which the mean EC was 0.39 microgram/ml (SD = 0.29). In 102 patients (missing albumin values in 4 of 106 patients), the concentration of etoposide not bound to protein (Efree) was estimated based on the following equation: percentage unbound = (1.4 x total bilirubin) - (6.8 x albumin) + 34.4. Regression analysis revealed that increasing age was correlated with higher EC (r = 0.27; two-tailed P < 0.01) and Efree (r = 0.31; two-tailed P < 0.01). Higher EC and Efree values were associated with lower WBC counts and absolute neutrophil counts after the first treatment course in 83 patients with nadir counts. Using multiple linear regression, a pharmacodynamic model was developed that included EC or Efree, age, and alkaline phosphatase. An interaction with bone marrow results at diagnosis was found, indicating a sharper decline in nadir counts with increasing EC or Efree when the marrow was involved with small cell lung cancer. This model explained 29% of the variation for WBC nadirs (P < 0.001) and 31% of the variation for absolute neutrophil count nadirs (P < 0. 001). Neither EC nor Efree showed a significant correlation with tumor response. A pharmacokinetic relationship between EC or Efree and age was found. A pharmacodynamic model could be developed for toxicity but not for tumor response.

Administration, Oral↗

PubMed1996

Inhibition of HIV-1 Rev-RRE interaction by diphenylfuran derivatives.

The interactions between RNA structures, such as RRE in the HIV-1 genome, and proteins, such as Rev of HIV-1, are essential for efficient viral replication. Compounds that bind specifically to such RNAs and disrupt their protein complexes offer a novel mechanism for inhibition of replication of the virus. As a step in this approach, we have designed and characterized a series of synthetic diphenylfuran cations that selectively inhibit Rev binding to RRE. Fluorescence titrations and gel band-shift results indicate that the diphenylfurans bind to RRE and inhibit Rev complex formation in a structure-dependent manner. The derivative with the greatest affinity for RRE has an association constant of greater than 10(7) M-1 and inhibits formation of the Rev--RRE complex at concentrations below 1 microM. It binds to RRE considerably more strongly than it binds to simple RNA duplexes. Spectral changes and energy transfer results on complex formation suggest that the compound has a nonclassical intercalation binding mode. CD studies with modified RRE hairpins indicate that the active diphenylfurans bind at the structured internal loop of RRE and cause a conformational change. The most active diphenylfurans are tetracations that appear to bind to RRE by a threading intercalation mode and cause a conformational change in the RNA that is essential for inhibition of Rev complex formation with RRE.

Amidines↗

PubMed1996

Interaction of U2AF65 RS region with pre-mRNA branch point and promotion of base pairing with U2 snRNA [corrected].

The mammalian splicing factor U2AF65 binds to the polypyrimidine tract adjacent to the 3' splice site and promotes assembly of U2 small nuclear ribonucleoprotein on the upstream branch point, an interaction that involves base pairing with U2 small nuclear RNA (snRNA). U2AF65 contains an RNA binding domain, required for interaction with the polypyrimidine tract, and an arginine-serine-rich (RS) region, required for U2 snRNP recruitment and splicing. Here it is reported that binding of U2AF65 to the polypyrimidine tract directed the RS domain to contact the branch point and promoted U2 snRNA-branch point base pairing even in the absence of other splicing factors. Analysis of RS domain mutants indicated that the ability of U2AF65 to contact the branch point, to promote the U2 snRNA-branch point interaction, and to support splicing are related activities, requiring only a few basic amino acids. Thus, the U2AF65 RS domain plays a direct role in modulating spliceosomal RNA-RNA interactions.

Amino Acid Sequence↗

PubMed1996

Yeast TAF(II)90 is required for cell-cycle progression through G2/M but not for general transcription activation.

The RNA polymerase II general transcription factor TFIID is a multisubunit complex comprising TATA-box binding protein and associated factors (TAFIIs). In vitro experiments have suggested that TAFIIs are essential coactivators required for RNA polymerase II-directed transcription activation. Here, for the first time, we analyze systematically the in vivo function of a specific TAFII, yeast TAFII90 (yTAFII90). We show that functional inactivation of yTAFII90 by temperature-sensitive mutations or depletion leads to arrest at the G2/M phase of the cell cycle. Unexpectedly, in the absence of functional yTAFII90, a variety of endogenous yeast genes were all transcribed normally, including those driven by well-characterized activators. Taken together, our results indicate that yTAFII90 is not required for transcription activation in general, and reveal linkages between TAF function and cell-cycle progression.

Alleles↗

PubMed1996

Transcription activation in cells lacking TAFIIS.

The general transcription factor TFIID is composed of the TATA-box-binding protein (TBP) and a set of TBP-associated factors (TAFIIs). In vitro, TAFIIs are required for activated transcription, and have been proposed to be obligatory targets of transcriptional activator proteins (activators)2. The function of TAFIIs has not been investigated systematically in vivo. A Saccharomyces cerevisiae TAFII complex (yTAFII complex) has been identified that shares functional and structural similarities with higher eukaryotic TFIID. In particular, most yTAFIIs are the homologue of a higher eukaryotic TAFII. Here we report that inactivation or depletion of six different yTAFIIs, including the core yTAFII, that contacts TBP, does not compromise transcriptional activation. We conclude that in vivo, activated transcription of many genes can occur in the absence of functional yTAFIIS, and that in these instances another transcription component(s) must be the target of the activator.

Antigens, Neoplasm↗

PubMed1996

Improved survival in stage III non-small-cell lung cancer: seven-year follow-up of cancer and leukemia group B (CALGB) 8433 trial.

BACKGROUND: For many years, high dose radiation therapy was the standard treatment for patients with locally or regionally advanced non-small-cell lung cancer (NSCLC), despite a 5-year survival rate of only 3%-10% following such therapy. From May 1984 through May 1987, the Cancer and Leukemia Group B (CALGB) conducted a randomized trial that showed that induction chemotherapy before radiation therapy improved survival during the first 3 years of follow-up. PURPOSE: This report provides data for 7 years of follow-up of patients enrolled in the CALGB trial. METHODS: The patient population consisted of individuals who had clinical or surgical stage III, histologically documented NSCLC; a CALGB performance status of 0-1; less than 5% loss of body weight in the 3 months preceding diagnosis; and radiographically visible disease. Patients were randomly assigned to receive either 1) cisplatin (100 mg/m2 body surface area intravenously on days 1 and 29) and vinblastine (5 mg/m2 body surface area intravenously weekly on days 1, 8, 15, 22, and 29) followed by radiation therapy with 6000 cGy given in 30 fractions beginning on day 50 (CT-RT group) or 2) radiation therapy with 6000 cGy alone beginning on day 1 (RT group) for a maximum duration of 6-7 weeks. Patients were evaluated for tumor regression if they had measurable or evaluable disease and were monitored for toxic effects, disease progression, and date of death. RESULTS: There were 78 eligible patients randomly assigned to the CT-RT group and 77 randomly assigned to the RT group. Both groups were similar in terms of sex, age, histologic cell type, performance status, substage of disease, and whether staging had been clinical or surgical. All patients had measurable or evaluable disease at the time of random assignment to treatment groups. Both groups received a similar quantity and quality of radiation therapy. As previously reported, the rate of tumor response, as determined radiographically, was 56% for the CT-RT group and 43% for the RT group (P = .092). After more than 7 years of follow-up, the median survival remains greater for the CT-RT group (13.7 months) than for the RT group (9.6 months) (P = .012) as ascertained by the logrank test (two-sided). The percentages of patients surviving after years 1 through 7 were 54, 26, 24, 19, 17, 13, and 13 for the CT-RT group and 40, 13, 10, 7, 6, 6, and 6 for the RT group. CONCLUSIONS: Long-term follow-up confirms that patients with stage III NSCLC who receive 5 weeks of chemotherapy with cisplatin and vinblastine before radiation therapy have a 4.1-month increase in median survival. The use of sequential chemotherapy-radiotherapy increases the projected proportion of 5-year survivors by a factor of 2.8 compared with that of radiotherapy alone. However, inasmuch as 80%-85% of such patients still die within 5 years and because treatment failure occurs both in the irradiated field and at distant sites in patients receiving either sequential chemotherapy-radiotherapy or radiotherapy alone, the need for further improvements in both the local and systemic treatment of this disease persists.

Antineoplastic Agents, Phytogenic↗

PubMed1996

Transcriptional elongation and cancer. Tumorigenesis.

Recent discoveries indicate that transcriptional elongation is an important regulatory step in gene expression, and that deregulation of elongation can lead to the development of certain malignancies.

Gene Expression Regulation, Neoplastic↗

PubMed1996

HIV Rev uses a conserved cellular protein export pathway for the nucleocytoplasmic transport of viral RNAs.

BACKGROUND: The structural proteins of human immunodeficiency virus type 1 (HIV-1) are encoded by intron-containing mRNAs that normally are retained in the nucleus. A viral regulatory protein, Rev, specifically induces the accumulation of these transcripts in the cytoplasm. Rev is an RNA-binding protein that also contains an 'effector' domain. The Rev effector domain has recently been shown to function as an autonomous nuclear export signal (NES) that, when fused to a foreign protein, will cause its rapid nuclear export. We and others have recently reported the cloning of a human protein (hRIP/Rab), that specifically interacts with the effector domain of Rev. RESULTS: Here we show that the NESs contained within two cellular proteins, PKI and I kappa B, which are not involved in RNA metabolism, also interact with hRIP. Fusion of these cellular sequences to the Rev RNA-binding domain reconstitutes a functional Rev protein. In addition to hRIP, these NESs also bind to several nuclear pore complex (NPC). We show that this protein export pathway is highly conserved by demonstrating that mammalian NESs also function in yeast. CONCLUSIONS: Our results indicate that the HIV-1 Rev protein evolved to take advantage of a cellular protein export pathway in order to allow the nucleocytoplasmic transport of unspliced viral RNA. Our data suggest a model in which the export substrate is translocated through the NPC by sequential interactions with different nucleoporins. Finally, our experiment suggests a mechanism by which I kappa B can downregulate nuclear NF kappa B activity by causing its rapid export from the nucleus.

Binding Sites↗

PubMed1996

Patterns of disease failure after trimodality therapy of nonsmall cell lung carcinoma pathologic stage IIIA (N2). Analysis of Cancer and Leukemia Group B Protocol 8935.

BACKGROUND: The impact of sequential trimodality therapy on the pattern of first site disease failure in pathologic Stage IIIA (N2) nonsmall cell lung carcinoma (NSCLC) was analyzed. METHODS: Seventy-four eligible patients with histologically documented Stage IIIA (N2) NSCLC underwent sequential trimodality therapy on Cancer and Leukemia Group B (CALGB) Protocol 8935. Treatment consisted of 2 cycles of induction cisplatin at 100 mg/m2 intravenously (i.v.) (Days 1 and 29) and vinblastine at 5 mg/m2 i.v. weekly for 5 weeks followed by surgery. Surgery included a thoracotomy with resection of the primary tumor and hilar lymph nodes and a mediastinal lymph node dissection. Patients with resected disease then received an additional a cycles of cisplatin at 100 mg/m2 i.v. and vinblastine at 5 mg/m2 i.v. biweekly for 2 total of 4 doses followed by consolidative thoracic irradiation. Patients with completely resected disease received 54 Gray (Gy) whereas those with incompletely resected disease received 59.4 Gy at 1.8 Gy/fraction (fx) once a day. Patients with unresectable disease underwent thoracic radiation therapy (TRT) treatments only to 59.4 Gy at 1.8 Gy/fx without any additional chemotherapy. Disease recurrence was determined by clinical, radiographic, or histologic criteria. Pattern of disease failure was identified by site of involvement at first recurrence as indicated by the CALGB Respiratory Follow-Up Form. RESULTS: Sixty-three of the 74 patients completed the induction chemotherapy as planned. Forty-six of the 63 patients underwent resection of disease whereas the remaining 17 were unresectable. Thirty-three of the 46 resected patients completed the entire adjuvant postoperative chemoradiation treatment as planned. Ten of 17 patients with unresectable disease completed postsurgical TRT. At a median follow-up interval of 27 months (range, 4-43), the 3-year overall survival and failure-free survival were 23% and 18%, respectively, for all 74 eligible patients. Overall, disease failure has occurred in 52 (70%) of the 74 eligible patients: local only: 13 (25%); distant only: 16 (31%); and both local and distant: 23 (44%), (P = not significant [NS]). Ten patients progressed during induction chemotherapy: local only: six patients; and both local and distant failure: four patients. Twenty-eight of 46 resected patients recurred: local only: 1 (4%); both local and distant failure: 11 (39%); and distant only: 16 (57%); (P < 0.001). Disease progression occurred in 14 of 17 patients with unresectable disease: local only: 6; both local and distant sites: 8. Among the 52 total patients experiencing disease relapse, isolated or combined local failure occurred commonly among patients during induction chemotherapy (n = 10, [28%]), in those with unresectable disease (n = 14, [39%]), or in those with resected disease (n = 12, [33%]), (P = NS). However, isolated or combined distant failure was more likely to occur among patients with resected disease (n = 27, [69%]) than either during induction chemotherapy (n = 4, [10%]) or in those with unresected disease (n = 8, [21%]), (P < 0.05). Among patients who relapsed, brain metastases occurred in 13 of 52 (25%) patients overall and in 12 of 28 (43%) patients with resected disease. CONCLUSIONS: Overall, disease failure was just as likely to occur in local, distant, or combined sites on CALGB Protocol 8935 using sequential trimodality therapy in the treatment of pathologic Stage IIIA (N2) NSCLC: Isolated or combined local failure occurred commonly during sequential tri-modality therapy whereas isolated or combined distant relapse was prevalent among patients with resected disease. In addition, isolated local failure was rare among patients with resected disease. The pattern of disease failure on CALGB Protocol 8935 reflects the biology of locoregional NSCLC as much as the therapeutic impact of trimodality therapy.

Adenocarcinoma↗

PubMed1996

The gene for human U2 snRNP auxiliary factor small 35-kDa subunit (U2AF1) maps to the progressive myoclonus epilepsy (EPM1) critical region on chromosome 21q22.3.

We used targeted exon trapping to clone portions of genes from human chromosome 21q22.3. One trapped sequence showed complete homology with the cDNA of human U2AF35 (M96982; HGM-approved nomenclature U2AF1), which encodes for the small 35-kDa subunit of the U2 snRNP auxiliary factor. Using the U2AF1 cDNA as a probe, we mapped this gene to cosmid Q15D2, a P1, and YAC 350F7 of the Chumakov et al. (Nature 359: 380, 1992) contig, close to the cystathionine-beta-synthase gene (CBS) on 21q22.3. This localization was confirmed by PCR using oligonucleotides from the 3' UTR and by FISH. As U2AF1 associates with a number of different factors during mRNA splicing, overexpression in trisomy 21 individuals could contribute to some Down syndrome phenotypes by interfering with the splicing process. Furthermore, because this gene maps in the critical region for the progressive myoclonus epilepsy I locus (EPM1), mutation analysis will be carried out in patients to evaluate the potential role of U2AF1 as a candidate for EPM1.

Base Sequence↗

PubMed1996

Intramolecular inhibition of activating transcription factor-2 function by its DNA-binding domain.

ATF-2 is a cellular basic region-leucine zipper (bZIP) transcription factor that can mediate diverse transcriptional responses, including activation by the adenovirus Ela protein. ATF-2 contains an activation domain, required for transcriptional activity, but in the absence of an appropriate inducer, full-length ATF-2 is transcriptionally inactive. Here we have investigated the mechanism underlying this regulated inhibition of ATF-2 transcriptional activity. We show that the region of ATF-2 that suppresses the activation region is the bZIP DNA-binding domain and that maximal inhibition requires both the basic region and leucine zipper subdomains. Inhibition is activation domain specific: The ATF-2 bZIP suppresses the ATF-2 and the related Ela activation domains but not acidic- and glutamine-rich activation domains. In vitro protein interaction assays demonstrate that the ATF-2 activation domain and bZIP specifically bind to one another. Finally, we show that bZIP-mediated inhibition can be modulated in a cell-type-specific manner by another sequence element within ATF-2. On the basis of these and other data, we propose that the ATF-2 bZIP and activation domain are engaged in an inhibitory intramolecular interaction and that inducers of ATF-2 disrupt this interaction to activate transcription.

Activating Transcription Factor 2↗

PubMed1996

A novel, mitogen-activated nuclear kinase is related to a Drosophila developmental regulator.

Although the ultimate targets of many signal transduction pathways are nuclear transcription factors, the vast majority of known protein kinases are cytosolic. Here, we report on a novel human kinase that is present exclusively in the nucleus. Kinase activity is increased upon cellular proliferation and is markedly elevated in patients with acute and chronic lymphocytic leukemias. We have identified a human gene that encodes this nuclear kinase and find that it is closely related to Drosophila female sterile homeotic (fsh), a developmental regulator with no known biochemical activity. Collectively, these results suggest that this nuclear kinase is a component of a signal transduction pathway that plays a role in Drosophila development and human growth control.

Adolescent↗