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Korsisaari N, Mäkelä TP. Interactions of Cdk7 and Kin28 with Hint/PKCI-1 and Hnt1 histidine triad proteins. J Biol Chem 2000; 275:34837-40. [PMID: 10958787 DOI: 10.1074/jbc.c000505200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclin-dependent kinase 7 (Cdk7) forms a trimeric complex with cyclin H and Mat1 to form the mammalian Cdk-activating kinase, CAK, as well as a part of the basal transcription factor TFIIH, where Cdk7 phosphorylates the C-terminal domain (CTD) of the large subunit of RNA polymerase II. Here, we report a novel interaction between Cdk7 and a histidine triad (HIT) family protein, Hint/PKCI-1. This interaction was initially observed in a yeast two-hybrid study and subsequently verified by co-immunoprecipitation and subcellular localization studies, where overexpression of Cdk7 leads to partial relocalization of Hint to the nucleus. The physical association is independent of cyclin H binding or Cdk7 kinase activity and is conserved between the related Sacharomyces cerevisiae CTD kinase Kin28 and the HIT protein Hnt1. Furthermore, combination of a disruption of HNT1 and a KIN28 temperature-sensitive allele in S. cerevisiae led to highly elongated cell morphology and reduced colony formation, indicating a genetic interaction between KIN28 and HNT1. The physical and genetic interactions of Hint and Hnt1 with Cdk7 and Kin28 suggest a role for this class of histidine triad proteins in the regulation of Cdk7 and Kin28 functions.
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Ojala PM, Yamamoto K, Castaños-Vélez E, Biberfeld P, Korsmeyer SJ, Mäkelä TP. The apoptotic v-cyclin-CDK6 complex phosphorylates and inactivates Bcl-2. Nat Cell Biol 2000; 2:819-25. [PMID: 11056537 DOI: 10.1038/35041064] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
v-cyclin encoded by Kaposi's sarcoma herpesvirus/human herpesvirus 8 (KSHV or HHV8) associates with cellular cyclin-dependent kinase 6 (CDK6) to form a kinase complex that promotes cell-cycle progression, but can also induce apoptosis in cells with high levels of CDK6. Here we show that whereas HHV8-encoded v-Bcl-2 protects against this apoptosis, cellular Bcl-2 has lost its anti-apoptotic potential as a result of an inactivating phosphorylation in its unstructured loop region. Moreover, we identify Bcl-2 as a new substrate for v-cyclin-CDK6 in vitro, and show that it is present in a complex with CDK6 in cell lysates. A Bcl-2 mutant with a S70A S87A double substitution in the loop region is not phosphorylated and provides resistance to apoptosis, indicating that inactivation of Bcl-2 by v-cyclin-CDK6 may be required for the observed apoptosis. Furthermore, the identification of phosphorylated Bcl-2 in HHV8-positive Kaposi's sarcoma indicates that HHV8-mediated interference with host apoptotic signalling pathways may encourage the development of Kaposi's sarcoma.
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53
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Avela K, Lipsanen-Nyman M, Idänheimo N, Seemanová E, Rosengren S, Mäkelä TP, Perheentupa J, Chapelle AD, Lehesjoki AE. Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism. Nat Genet 2000; 25:298-301. [PMID: 10888877 DOI: 10.1038/77053] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mulibrey nanism (for muscle-liver-brain-eye nanism, MUL; MIM 253250) is an autosomal recessive disorder that involves several tissues of mesodermal origin, implying a defect in a highly pleiotropic gene. Characteristic features include severe growth failure of prenatal onset and constrictive pericardium with consequent hepatomegaly. In addition, muscle hypotonia, J-shaped sella turcica, yellowish dots in the ocular fundi, typical dysmorphic features and hypoplasia of various endocrine glands causing hormonal deficiency are common. About 4% of MUL patients develop Wilms' tumour. MUL is enriched in the Finnish population, but is rare elsewhere. We previously assigned MUL to chromosome 17q22-q23 and constructed a physical contig over the critical MUL region. The region has now been further refined by haplotype analysis and new positional candidate genes have been localized. We identified a gene with four independent MUL-associated mutations that all cause a frameshift and predict a truncated protein. MUL is ubiquitously expressed and encodes a new member of the RING-B-box-Coiled-coil (RBCC) family of zinc-finger proteins, whose members are involved in diverse cellular functions such as developmental patterning and oncogenesis.
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54
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Vallenius T, Luukko K, Mäkelä TP. CLP-36 PDZ-LIM protein associates with nonmuscle alpha-actinin-1 and alpha-actinin-4. J Biol Chem 2000; 275:11100-5. [PMID: 10753915 DOI: 10.1074/jbc.275.15.11100] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PDZ-LIM family of proteins (Enigma/LMP-1, ENH, ZASP/Cypher, RIL, ALP, and CLP-36) has been suggested to act as adapters that direct LIM-binding proteins to the cytoskeleton. Most interactions of PDZ-LIM proteins with the cytoskeleton have been identified in striated muscle, where several PDZ-LIM proteins are predominantly expressed. By contrast, CLP-36 mRNA is expressed in several nonmuscle tissues, and here we demonstrate high expression of CLP-36 in epithelial cells by in situ hybridization analysis. Our subcellular localization studies indicate that in nonmuscle cells, CLP-36 protein localizes to actin stress fibers. This localization is mediated via the PDZ domain of CLP-36 that associates with the spectrin-like repeats of alpha-actinin. Interestingly, immunoprecipitation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis indicate that both nonmuscle alpha-actinin-1 and alpha-actinin-4 form complexes with CLP-36. The high expression of alpha-actinin-4 in the colon, together with these results, suggests a specific function for the alpha-actinin-4-CLP-36 complex in the colonic epithelium. More generally, results presented here demonstrate that the association of PDZ-LIM proteins with the cytoskeleton extends to the actin stress fibers of nonmuscle cells.
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Ojala PM, Tiainen M, Salven P, Veikkola T, Castaños-Vélez E, Sarid R, Biberfeld P, Mäkelä TP. Kaposi's sarcoma-associated herpesvirus-encoded v-cyclin triggers apoptosis in cells with high levels of cyclin-dependent kinase 6. Cancer Res 1999; 59:4984-9. [PMID: 10519412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) has a key etiological role in development of Kaposi's sarcoma (KS). v-Cyclin is a KSHV-encoded homologue to D-type cyclins that associates with cellular cyclin-dependent kinase 6 (CDK6). v-Cyclin promotes S-phase entry of quiescent cells and has been suggested to execute functions of both D- and E-type cyclins. In this study, expression of v-cyclin in cells with elevated levels of CDK6 led to apoptotic cell death after the cells entered S phase. The cell death required the kinase activity of CDK6 because cells expressing a kinase-deficient form of CDK6 did not undergo apoptosis upon v-cyclin expression. Studies on the mechanisms involved in this caspase-3-mediated apoptosis indicated that it was independent of cellular p53 or pRb status, and it was not suppressed by Bcl-2. In contrast, the KSHV-encoded v-Bcl-2 efficiently suppressed v-cyclin-/CDK6-induced apoptosis, demonstrating a marked difference in the antiapoptotic properties of c-Bcl-2 and v-Bcl-2. In KS lesions, high CDK6 expression was confined to a subset of cells, some of which displayed signs of apoptosis. These results suggest that v-cyclin may exert both growth-promoting and apoptotic functions in KS, depending on factors regulating CDK6 and v-Bcl-2 levels.
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Tiainen M, Ylikorkala A, Mäkelä TP. Growth suppression by Lkb1 is mediated by a G(1) cell cycle arrest. Proc Natl Acad Sci U S A 1999; 96:9248-51. [PMID: 10430928 PMCID: PMC17765 DOI: 10.1073/pnas.96.16.9248] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Germ-line mutations of LKB1 (STK11) lead to Peutz-Jeghers syndrome characterized by gastrointestinal polyps and cancer of different organ systems. The mutations lead to loss or severe impairment of Lkb1 serine/threonine kinase activity. Therefore LKB1 has been implicated as a tumor suppressor gene, but only a few mutations in the coding exons of LKB1 have been detected in sporadic tumors. Here, we have identified tumor cell lines with severely reduced mRNA levels and impaired Lkb1 kinase activity. Reintroducing Lkb1 into these cells suppressed cell growth. The Lkb1-mediated growth inhibition was caused by a G(1) cell cycle block and was not detected with several naturally occurring Lkb1 mutants. These results indicate that LKB1 has functional and specific growth-suppressing activity.
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Luukko K, Ylikorkala A, Tiainen M, Mäkelä TP. Expression of LKB1 and PTEN tumor suppressor genes during mouse embryonic development. Mech Dev 1999; 83:187-90. [PMID: 10381580 DOI: 10.1016/s0925-4773(99)00050-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Germ-line mutations of LKB1 and PTEN tumor suppressor genes underlie the phenotypically related Peutz-Jeghers syndrome (PJS) and Cowden disease (CD), respectively. To analyze possible developmental roles of PTEN and LKB1, we have studied their mRNA expression during mouse embryonic development (E7-17.5) by in situ hybridization. Ubiquitous expression of both genes during early stages (E7-11) became more restricted in later embryonic development (E15-19) where LKB1 and PTEN showed prominent overlapping expression in e.g. gastrointestinal tract and lung. In contrast, LKB1 was selectively expressed at high levels in testis and PTEN was prominently expressed in skin epithelium and underlying mesenchyme. These results indicate that LKB1 and PTEN display largely overlapping expression patterns during embryonic development. Moreover, a high expression of these genes was observed in the tissues and organs affected in PJS and CD patients and in PTEN+/- mice.
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Ylikorkala A, Avizienyte E, Tomlinson IP, Tiainen M, Roth S, Loukola A, Hemminki A, Johansson M, Sistonen P, Markie D, Neale K, Phillips R, Zauber P, Twama T, Sampson J, Järvinen H, Mäkelä TP, Aaltonen LA. Mutations and impaired function of LKB1 in familial and non-familial Peutz-Jeghers syndrome and a sporadic testicular cancer. Hum Mol Genet 1999; 8:45-51. [PMID: 9887330 DOI: 10.1093/hmg/8.1.45] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Germline mutations in LKB1 have been reported to underlie familial Peutz-Jeghers syndrome (PJS) with intestinal hamartomatous polyps and an elevated risk of various neoplasms. To investigate the prevalence of LKB1 germline mutations in PJS more generally, we studied samples from 33 unrelated PJS patients including eight non-familial sporadic patients, 20 familial patients and five patients with unknown family history. Nineteen germline mutations were identified, 12 (60%) in familial and four (50%) in sporadic cases. LKB1 mutations were not detected in 14 (42%) patients, indicating that the existence of additional minor PJS loci cannot be excluded. LKB1 is predicted to encode a serine/threonine kinase. To demonstrate the putative Lkb1 kinase function and to study the consequences of LKB1 mutations in PJS and sporadic tumors, we have analyzed the kinase activity of wild-type and mutant Lkb1 proteins. Interestingly, while most of the small deletions or missense mutations resulted in loss-of-function alleles, one missense mutation (G163D) previously identified in a sporadic testicular tumor demonstrated severely impaired but detectable kinase activity.
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59
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Hermand D, Pihlak A, Westerling T, Damagnez V, Vandenhaute J, Cottarel G, Mäkelä TP. Fission yeast Csk1 is a CAK-activating kinase (CAKAK). EMBO J 1998; 17:7230-8. [PMID: 9857180 PMCID: PMC1171069 DOI: 10.1093/emboj/17.24.7230] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cell cycle progression is dependent on the sequential activity of cyclin-dependent kinases (CDKs). For full activity, CDKs require an activating phosphorylation of a conserved residue (corresponding to Thr160 in human CDK2) carried out by the CDK-activating kinase (CAK). Two distinct CAK kinases have been described: in budding yeast Saccharomyces cerevisiae, the Cak1/Civ1 kinase is responsible for CAK activity. In several other species including human, Xenopus, Drosophila and fission yeast Schizosaccharomyces pombe, CAK has been identified as a complex homologous to CDK7-cyclin H (Mcs6-Mcs2 in fission yeast). Here we identify the fission yeast Csk1 kinase as an in vivo activating kinase of the Mcs6-Mcs2 CAK defining Csk1 as a CAK-activating kinase (CAKAK).
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60
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Kim JO, Nau MM, Allikian KA, Mäkelä TP, Alitalo K, Johnson BE, Kelley MJ. Co-amplification of a novel cyclophilin-like gene (PPIE) with L-myc in small cell lung cancer cell lines. Oncogene 1998; 17:1019-26. [PMID: 9747881 DOI: 10.1038/sj.onc.1202006] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Specific genetic alterations affecting proto-oncogenes of the myc gene family are frequently detected in human lung cancer. Among 11 SCLC cell lines with L-myc gene amplification, four were found to have alteration of the RLF gene by Southern blot and RT-PCR analyses. One cell line, NCI-H378, contained aberrantly-sized L-myc-hybridizing bands by Southern and Northern blot hybridization but had no alteration of RLF. Some L-myc-hybridizing cDNAs from NCI-H378 contained a novel sequence with close homology to the cyclophilins joined to antisense L-myc exon 2 sequence. Full length cDNAs isolated from human skeletal muscle containing only the novel sequence identify open reading frames of 301 and 296 amino acids and differ in the C-terminal region by 22 and 17 amino acids. This gene, tentatively named PPIE (peptidyl-prolyl cis-trans isomerase E), has 83% amino acid identity with the central conserved region of cyclophilin A, is evolutionarily conserved by Southern blot, and exhibits differential tissue expression with highest levels found in muscle and brain. Co-amplification of PPIE was observed in seven of eleven L-myc amplified cell lines. Analysis of radiation hybrids suggests that the gene order is RLF-PPIE-L-myc on chromosome 1p and pulse-field gel electrophoresis localizes all three genes to an 800 megabase Mlu I fragment. The prognostic and functional consequences of PPIE gene amplification in SCLC can now be determined.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Carcinoma, Small Cell/genetics
- Carcinoma, Small Cell/metabolism
- Chromosomes, Human, Pair 1/genetics
- Cyclophilins
- DNA, Complementary/chemistry
- DNA, Complementary/isolation & purification
- Electrophoresis, Gel, Pulsed-Field
- Gene Amplification
- Genes, myc
- Humans
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Molecular Sequence Data
- Peptidylprolyl Isomerase/biosynthesis
- Peptidylprolyl Isomerase/chemistry
- Peptidylprolyl Isomerase/genetics
- Peptidylprolyl Isomerase/metabolism
- Translocation, Genetic
- Tumor Cells, Cultured
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Egyházi E, Ossoinak A, Lee JM, Greenleaf AL, Mäkelä TP, Pigon A. Heat-shock-specific phosphorylation and transcriptional activity of RNA polymerase II. Exp Cell Res 1998; 242:211-21. [PMID: 9665818 DOI: 10.1006/excr.1998.4112] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The carboxyl-terminal domain (CTD) of the largest RNA polymerase II (pol II) subunit is a target for extensive phosphorylation in vivo. Using in vitro kinase assays it was found that several different protein kinases can phosphorylate the CTD including the transcription factor IIH-associated CDK-activating CDK7 kinase (R. Roy, J. P. Adamczewski, T. Seroz, W. Vermeulen, J. P. Tassan, L. Schaeffer, E. A. Nigg, J. H. Hoeijmakers, and J. M. Egly, 1994, Cell 79, 1093-1101). Here we report the colocalization of CDK7 and the phosphorylated form of CTD (phosphoCTD) to actively transcribing genes in intact salivary gland cells of Chironomus tentans. Following a heat-shock treatment, both CDK7 and pol II staining disappear from non-heat-shock genes concomitantly with the abolishment of transcriptional activity of these genes. In contrast, the actively transcribing heat-shock genes, manifested as chromosomal puff 5C on chromosome IV (IV-5C), stain intensely for phosphoCTD, but are devoid of CDK7. Furthermore, the staining of puff IV-5C with anti-PCTD antibodies was not detectably influenced by the TFIIH kinase and transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). Following heat-shock treatment, the transcription of non-heat-shock genes was completely eliminated, while newly formed heat-shock gene transcripts emerged in a DRB-resistant manner. Thus, heat shock in these cells induces a rapid clearance of CDK7 from the non-heat-shock genes, indicating a lack of involvement of CDK7 in the induction and function of the heat-induced genes. The results taken together suggest the existence of heat-shock-specific CTD phosphorylation in living cells. This phosphorylation is resistant to DRB treatment, suggesting that not only phosphorylation but also transcription of heat-shock genes is DRB resistant and that CDK7 in heat shock cells is not associated with TFIIH.
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Attalla H, Westberg JA, Andersson LC, Adlercreutz H, Mäkelä TP. 2-Methoxyestradiol-induced phosphorylation of Bcl-2: uncoupling from JNK/SAPK activation. Biochem Biophys Res Commun 1998; 247:616-9. [PMID: 9647742 DOI: 10.1006/bbrc.1998.8870] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The natural estrogen metabolite 2-methoxyestradiol (2ME) is anti-angiogenic in vivo and a strong growth inhibitor in vitro. The growth inhibition is due to mitotic arrest and apoptosis. These effects are reminiscent of those induced by taxol, and appear to be mediated by inhibition of microtubule dynamics. Here we have studied the cellular response to 2ME in regard to potential mediators of the observed cellular changes. 2ME treatment increases the insoluble polymerized fraction of cellular tubulin similar to taxol, and in contrast to the microtubule depolymerizing drugs such as colcemid and vincristine. This stabilization following 2ME treatment is accompanied by phosphorylation and inactivation of Bcl-2 increasing gradually from 2-24 hours. To study the pathway leading to Bcl-2 phosphorylation we analyzed Raf-1 and JNK/SAPK kinases, both of which have been reported to be involved in Bcl-2 inactivation. Our results indicate that Raf-1 is phosphorylated in response to 2ME, but this occurs later than Bcl-2 phosphorylation suggesting that Raf-1 is not directly phosphorylating Bcl-2. JNK/SAPK was activated rapidly after 2ME treatment. However, this activation was transient and returned to undetectable levels by 2 hours of treatment, demonstrating that JNK/SAPK is not directly phosphorylating Bcl-2. Taken together with previous results indicating that overexpression of JNK/SAPK leads to Bcl-2 phosphorylation, our results would support a model where JNK/SAPK is indirectly phosphorylating Bcl-2.
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Attalla H, Knuutila S, Mäkelä TP, Andersson LC, Adlercreutz H. Cytogenetic chromosomal preparations using 2-methoxyestradiol. CANCER GENETICS AND CYTOGENETICS 1998; 102:139-41. [PMID: 9546067 DOI: 10.1016/s0165-4608(97)00341-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The antimitotic drug 2-methoxyestradiol is an end metabolite of catechol estrogens. In vivo, it arrests cells in mitosis by interfering with the dynamics of the mitotic spindle without disrupting tubulin formation. It has a mitotic index similar to that of Colcemid in different cell lines. Here we report that 2-methoxyestradiol can be used for making cytogenetic preparations of comparable quality to that of colcemid. In addition, 2-methoxyestradiol is devoid of the toxicity associated with Colcemid, which may make 2-methoxyestradiol useful in slowly growing samples often found in primary solid tumor cultures where a sufficient number of mitotic cells is difficult to obtain.
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Attalla H, Mäkelä TP, Wähälä K, Rasku S, Andersson LC, Adlercreutz H. 2,6-Bis((3,4-dihydroxyphenyl)-methylene)cyclohexanone (BDHPC)-induced apoptosis and p53-independent growth inhibition: synergism with genistein. Biochem Biophys Res Commun 1997; 239:467-72. [PMID: 9344853 DOI: 10.1006/bbrc.1997.7495] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Estrogen binds to two classes of proteins in the cells, the high-affinity estrogen receptor (ER) as well as a low affinity estrogen type II binding site (EBS-II). Methyl p-hydroxyphenyllactate (MeHPLA) is an endogenous ligand for EBS-II. Binding of MeHPLA to EBS-II has a growth regulatory effect in estrogen-responsive cells, and levels of MeHPLA are decreased in breast cancer due to degradation by a specific esterase. 2,6-bis((3, 4-dihydroxyphenyl)-methylene) cyclohexanone (BDHPC) is an esterase-resistant analogue of MeHPLA which binds irreversibly to EBS-II and inhibits growth of breast cancer cells. In the present study, we analyzed the mechanism of growth inhibition by BDHPC. Treatment with BDHPC resulted in accumulation of cells in G1 phase and apoptosis. The G1 accumulation was not dependent on a functional p53 gene. The G1-specific growth inhibition by BDHPC was found to act synergistically with the G2/M-specific inhibition induced by the tyrosine kinase inhibitor genistein, suggesting this drug combination could be effectively used in cancer treatment.
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Attalla H, Mäkelä TP, Adlercreutz H, Andersson LC. 2-Methoxyestradiol arrests cells in mitosis without depolymerizing tubulin. Biochem Biophys Res Commun 1996; 228:467-73. [PMID: 8920936 DOI: 10.1006/bbrc.1996.1683] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The endogenous estrogen metabolite 2-methoxyestradiol (2-MeOE2) suppresses experimental tumor growth in vivo and inhibits angiogenesis activity in vitro. Moreover, 2-MeOE2 has been observed to block mitosis in cell cultures. As high concentrations of 2-MeOE2 prevent microtubule assembly in vitro, the mitotic arrest has been attributed to inhibition of tubulin polymerization. Here we report that concentrations of 2-MeOE2 that cause complete metaphasal arrest do not inhibit the assembly of mitotic spindles. In contrast to the chromosomal dispersal seen in cells arrested by the tubulin depolymerizing drug colcemid, the chromosomes of cells treated with 2-MeOE2 remained in the metaphasal plate indicating a functional defect of the mitotic spindle. The 2-MeOE2 arrest resembles those induced by compounds affecting microtubule dynamics such as taxol and vinblastine. The 2-MeOE2 block is also similar to that induced by several anti-calmodulin agents. Given that metaphase to anaphase transition is a calmodulin-dependent step and our observation that 2-MeOE2 inhibits calmodulin activity in vitro, we suggest that the 2-MeOE2 metaphasal arrest may occur via inhibition of calmodulin.
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66
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Herrera RE, Mäkelä TP, Weinberg RA. TGF beta-induced growth inhibition in primary fibroblasts requires the retinoblastoma protein. Mol Biol Cell 1996; 7:1335-42. [PMID: 8885230 PMCID: PMC275985 DOI: 10.1091/mbc.7.9.1335] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transforming growth factor beta (TGF beta) inhibits cell proliferation by inducing a G1 cell-cycle arrest. Cyclin/CDK complexes have been implicated in this arrest, because TGF beta treatment leads to inhibition of cyclin/CDK activity. We have investigated the role of the retinoblastoma protein (pRb) in TGF beta-induced growth arrest by using RB+/+ and RB-/- primary mouse embryo fibroblasts. In both of these cell types, TGF beta inhibits CDK4-associated kinase activity. However, whereas CDK2-associated kinase activity was completely inhibited by TGF beta in the wild-type cells, it was reduced only slightly in the RB mutant cells. In addition, at high-cell density the growth-inhibitory effects of TGF beta are no longer observed in the RB-/- cells; on the contrary, TGF beta treatment promotes the growth of these mutant fibroblasts. Thus, under certain cellular growth conditions, elimination of pRb transforms the growth-inhibitory effects of TGF beta into growth-stimulatory effects. These observations could help to explain why TGF beta is often found to enhance tumorigenicity in vivo and why inactivation of the RB gene leads to tumorigenesis.
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67
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Herrera RE, Sah VP, Williams BO, Mäkelä TP, Weinberg RA, Jacks T. Altered cell cycle kinetics, gene expression, and G1 restriction point regulation in Rb-deficient fibroblasts. Mol Cell Biol 1996; 16:2402-7. [PMID: 8628308 PMCID: PMC231229 DOI: 10.1128/mcb.16.5.2402] [Citation(s) in RCA: 248] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Fibroblasts prepared from retinoblastoma (Rb) gene-negative mouse embryos exhibit a shorter G1 phase of the growth cycle and smaller size than wild-type cells. In addition, the mutant cells are no longer inhibited by low levels of cycloheximide at any point in G1 but do remain sensitive to serum withdrawal until late in G1. Certain cell cycle-regulated genes showed no temporal or quantitative differences in expression. In contrast, cyclin E expression in Rb-deficient cells is deregulated in two ways. Cyclin E mRNA is generally derepressed in mutant cells and reaches peak levels about 6 h earlier in G1 than in wild-type cells. Moreover, cyclin E protein levels are higher in the Rb-/- cells than would be predicted from the levels of its mRNA. Thus, the selective growth advantage conferred by Rb gene deletion during tumorigenesis may be explained in part by changes in the regulation of cyclin E. In addition, the mechanisms defining the restriction point of late G1 may consist of at least two molecular events, one cycloheximide sensitive and pRb dependent and the other serum sensitive and pRb independent.
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68
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Mäkelä TP, Hellsten E, Vesa J, Hirvonen H, Palotie A, Peltonen L, Alitalo K. The rearranged L-myc fusion gene (RLF) encodes a Zn-15 related zinc finger protein. Oncogene 1995; 11:2699-704. [PMID: 8545128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have previously characterized intrachromosomal rearrangements at 1p32 fusing the first exon of the RLF gene with L-myc. Here we present the full-length cDNA sequence of the 6251 bp RLF mRNA. The predicted 1914 amino acid Rlf protein contains sixteen widely spaced zinc finger motifs, and is related to the Zn-15 transcription factor. RLF is widely expressed in fetal and adult tissues, suggesting that it has a general role in transcriptional regulation. The zinc fingers are not contained in the 79 amino acid N-terminal region of RLF involved in the RLF-L-myc fusions, and the transforming ability of the RLF-L-myc and the normal L-myc proteins is indistinguishable. These findings suggest that the role of the rearrangements fusing RLF and L-myc is to deregulate the tightly controlled expression of the L-myc gene.
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69
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Abstract
The cyclin-dependent kinase (CDK)-activating kinase, CAK, from mammals and amphibians consists of MO15/CDK7 and cyclin H, a complex which has been identified also as a RNA polymerase II C-terminal domain (CTD) kinase. While the Schizosaccharomyces pombe cdc2 gene product also requires an activating phosphorylation, the enzyme responsible has not been identified. We have isolated an essential S.pombe gene, mop1, whose product is closely related to MO15 and to Saccharomyces cerevisiae Kin28. The functional similarity of Mop1 and MO15 is reflected in the ability of MO15 to rescue a mop1 null allele. This suggests that Mop1 would be a CDK, and indeed Mop1 associates with a previously characterized cyclin H-related cyclin Mcs2 of S.pombe. Also, Mop1 and Mcs2 can associate with the heterologous partners human cyclin H and MO15, respectively. Moreover, the rescue of a temperature-sensitive mcs2 strain by expression of mop1+ demonstrates a genetic interaction between mop1 and mcs2. In a functional assay, immunoprecipitated Mop1-Mcs2 acts both as an RNA polymerase II CTD kinase and as a CAK. The CAK activity of Mop1-Mcs2 distinguishes it from the related CDK-cyclin pair Kin28-Ccl1 from S.cerevisiae, and supports the notion that Mop1-Mcs2 may represent a homolog of MO15-cyclin H in S.pombe with apparent dual roles as a RNA polymerase CTD kinase and as a CAK.
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70
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Heiskanen M, Hellsten E, Kallioniemi OP, Mäkelä TP, Alitalo K, Peltonen L, Palotie A. Visual mapping by fiber-FISH. Genomics 1995; 30:31-6. [PMID: 8595900 DOI: 10.1006/geno.1995.0005] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
FISH techniques have opened new possibilities for high-resolution genome mapping. Effective utilization of these techniques for the rapid orientation and ordering of adjacent and overlapping probes as well as for the characterization of long-range genomic contigs would facilitate physical mapping and positional cloning efforts. Here, we have evaluated our recently developed improved fiber-FISH technique for the physical mapping of a 500-kb region at 1p32 as well as for the detection of genomic rearrangement affecting this region. Our fiber-FISH technique is based on the hybridization of probes to unfixed linearized DNA fibers on a microscope slide. Preparation of the target DNA from cells embedded in pulsed-field gel electrophoresis (PFGE) blocks makes it possible to obtain long intact DNA fibers that give an excellent signal-to-noise ratio in FISH. The linear range of the method reached from 2 to 500 kb with a measuring accuracy approaching that of PFGE. Fiber-FISH was used to establish the order, orientation, and distances for several probes for this region, including six large insert phage, cosmid, and P1 clones and seven genomic subclones. This has significantly facilitated our efforts to develop a genomic contig for this region, recently discovered to contain the gene for inherited neuronal ceroid lipofuscinosis (INCL). Finally, we also demonstrated how rearrangements affecting the L-myc gene at this locus in small-cell lung cancer can be visualized with fiber-FISH. In conclusion, fiber-FISH is very useful for high-resolution physical mapping and contig evaluation as well as for detecting genetic rearrangements.
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71
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Akoulitchev S, Mäkelä TP, Weinberg RA, Reinberg D. Requirement for TFIIH kinase activity in transcription by RNA polymerase II. Nature 1995; 377:557-60. [PMID: 7566158 DOI: 10.1038/377557a0] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An array of tandem heptapeptide repeats at the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II constitute a highly conserved structure essential for viability. Studies have established that the CTD is phosphorylated at different stages of the transcription cycle, and that it may be involved in transcriptional regulation. The exact role of the CTD remains elusive, as in vitro reconstituted transcription using the adenovirus major late promoter does not require the CTD. Previous studies showed that transcription from the murine dihydrofolate reductase (DHFR) promoter can be only accomplished by the form of RNA polymerase II that contains the hypophosphorylated CTD (RNAPIIA), but not by the form that lacks it (RNAPIIB). Here we show that the CTD, but not its phosphorylation, is required for initiation of transcription. We also show that transcription requires CTD kinase activity provided by the CDK subunit of TFIIH.
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72
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Mäkelä TP, Oikari AO. Pentachlorophenol accumulation in the freshwater mussels Anodonta anatina and Pseudanodonta complanata, and some physiological consequences of laboratory maintenance. CHEMOSPHERE 1995; 31:3651-3662. [PMID: 8528651 DOI: 10.1016/0045-6535(95)00214-s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Freshwater mussels Anodanta anatina and Pseudanodonta complanata were exposed to (14C)-pentachlorophenol. The wet weight based bioconcentration factor (BCF = activity in animal per activity in water) at steady state varied from 80 to 120 for A. anatina and from 61 to 85 for P. complanata. The species did not differ significantly in their wet weight or lipid based BCFs but dry weight based values were significantly higher (40-50%) for A. anatina. The soft tissue dry weight and dry weight based condition index of A. anatina (Cl4 = soft tissue dry weight per shell length) differed significantly between natural mussel populations. In animals kept from 4 to 8 months in laboratory conditions, the soft tissue dry weight and glycogen content decreased more rapidly when mussels were maintained at 15 than at 5 degrees C. However, glycogen content in the digestive gland or adductor muscle did not differ in mussels maintained in the laboratory (5 degrees C) when compared to the natural population. The adductor muscle protein content differed between laboratory maintained animals and the natural population in Lake Höytiänen but there was no difference in the soft tissue lipid content. Trace metal concentrations and calcium in the soft tissue were in general higher in laboratory maintained mussels. In addition, laboratory maintenance affected the reproductive cycle of A. anatina.
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73
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Västrik I, Mäkelä TP, Koskinen PJ, Alitalo K. Determination of sequences responsible for the differential regulation of Myc function by delta Max and Max. Oncogene 1995; 11:553-60. [PMID: 7630640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The DNA-binding, transcriptional activation and transforming activities of the Myc protein require dimerization with Max. Max can form also homodimers which are able to bind the same DNA sequence as Myc/Max heterodimers and suppress Myc-induced transcription and transformation. We have recently identified a naturally occurring truncated form of Max, delta Max, which in a rat embryo fibroblast enhances transformation by Myc and Ras. Like Max, this delta Max protein contains a b-HLH-Zip domain, except that the end of the leucine zipper is replaced by five delta Max-specific amino acid residues. Delta Max also lacks the C-terminal sequences of Max including a nuclear localisation signal. Here we have dissected the regions responsible for the specific effects of Max and delta Max in Ras-Myc cotransformation of rat embryo fibroblasts. Our results indicate that the suppressive activity of Max requires C-terminal acidic and basic regions and an intact leucine zipper. Replacement of the end of the leucine zipper with the delta Max-specific sequence is responsible for the enhancement of transformation by delta Max. Surprisingly, delta Max does not require the DNA-binding basic region for enhancement of transformation and has no effect on Myc-induced transcription activation from Myc/Max-binding site-containing promoter construct.
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74
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Mäkelä TP, Parvin JD, Kim J, Huber LJ, Sharp PA, Weinberg RA. A kinase-deficient transcription factor TFIIH is functional in basal and activated transcription. Proc Natl Acad Sci U S A 1995; 92:5174-8. [PMID: 7761469 PMCID: PMC41871 DOI: 10.1073/pnas.92.11.5174] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Phosphorylation of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II has been suggested to be critical for transcription initiation, activation, or elongation. A kinase activity specific for CTD is a component of the general transcription factor TFIIH. Recently, a cyclin-dependent kinase-activator kinase (MO15 and cyclin H) was found to be associated with TFIIH preparations and was suggested to be the CTD kinase. TFIIH preparations containing mutant, kinase-deficient MO15 lack CTD kinase activity, indicating that MO15 is critical for polymerase phosphorylation. Nonetheless, these mutant TFIIH preparations were fully functional (in vitro) in both basal and activated transcription. These results indicate that CTD phosphorylation is not required for transcription with a highly purified system.
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75
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Serizawa H, Mäkelä TP, Conaway JW, Conaway RC, Weinberg RA, Young RA. Association of Cdk-activating kinase subunits with transcription factor TFIIH. Nature 1995; 374:280-2. [PMID: 7885450 DOI: 10.1038/374280a0] [Citation(s) in RCA: 284] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The RNA polymerase II large subunit contains an essential carboxy-terminal domain (CTD) believed to be involved in the response to regulators during transcription initiation. The CTD is phosphorylated on a portion of RNA polymerase II molecules in vivo and it can be phosphorylated by the general transcription factor TFIIH in vitro. A highly purified TFIIH from rat liver has been described; this, like human and yeast TFIIH, contains associated CTD kinase and helicase activities. We report here that two polypeptides of the purified mammalian TFIIH are the MO15/Cdk7 kinase and cyclin H subunits of the Cdk-activating kinase Cak, previously identified as a positive regulator of Cdc2 and Cdk2. TFIIH and Cak preparations are each capable of phosphorylating recombinant CTD and recombinant Cdk2 proteins. The presence of Cak in TFIIH indicates that Cak may have roles in transcriptional regulation and in cell-cycle control.
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