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PubMed2002

A transgenic mouse strain with antigen-specific T cells (RAG1KO/sf/OVA) demonstrates that the scurfy (sf) mutation causes a defect in T-cell tolerization.

The scurfy (sf) murine mutation causes severe lymphoproliferation, which results in death of hemizygous males (sf/Y) by 22 to 26 days of age. The CD4+ T cells are crucial mediators of this disease. Recent publications have not only identified this mutation as the genetic equivalent of the human disease X-linked neonatal diabetes mellitus, enteropathy, and endocrinopathy syndrome, but also have indicated that the defective protein-scurfin-is a new forkhead/winged-helix protein with a frameshift mutation, resulting in a product without the functional forkhead. These results have lead to speculation that the scurfy gene acts by disrupting the T-cell tolerance mechanism, resulting in hyperresponsiveness and lack of down-regulation. The Rag1KO/sf/Y OVA strain, with virtually 100% of its CD4+ T cells reactive strictly to ovalbumin (OVA) peptide 323-339, is an excellent model for determination of the sf mutation's ability to disrupt tolerance. We hypothesized that Rag1KO/sf/OVA mice would not be tolerant to antigen at a dose that tolerizes control animals. We found that splenic cells from Rag1KO/sf/Y OVA mice injected with the same dose of OVA peptide that induces tolerance in cells from control mice proliferate in vitro in response to OVA peptide. These results are consistent with a defect in the pathway responsible for peripheral T-cell tolerization.

Abatacept↗
PubMed2002

The hepatocyte nuclear factor 3 alpha gene, HNF3alpha (FOXA1), on chromosome band 14q13 is amplified and overexpressed in esophageal and lung adenocarcinomas.

Genomic amplification is observed in many, if not all, types of human malignancy and is one of the mechanisms for the activation of dominant-acting oncogenes in tumorigenesis. In the present study, three amplified restriction fragments were identified in an esophageal adenocarcinoma (P16) using the restriction landmark genome scanning two-dimensional gel technique. These fragments were cloned, sequenced, and mapped to chromosome band 14q13. Using the sequence tagged site-amplification mapping approach, we defined the core-amplified domain by screening 75 normal-tumor paired esophageal samples. The frequency of 14q13 amplification is 6.7% in esophageal tumors, and the amplicon spans >6 Mb in 1 tumor but is contained in a region <0.3 Mb in all of the remaining amplified tumors. Quantitative reverse transcription-PCR (RT-PCR) of 8 genes and expressed sequence tags located within the core-amplified domain revealed that the HNF3alpha (FOXA1)(4) gene, a forkhead gene family member, was overexpressed in all of the amplified esophageal tumors. HNF3alpha amplification was confirmed by Southern blot and interphase fluorescence in situ hybridization analyses, and the results of real-time RT-PCR were consistent with that of the regular quantitative RT-PCR. Increased immunohistochemical nuclear staining of the HNF3alpha protein was detected in all of the tumors containing 14q13 amplification. Affymetrix oligonucleotide microarrays of 86 lung adenocarcinomas demonstrated that expression of the HNF3alpha mRNA was elevated (> or =2.5-fold of mean expression in normal lung) in 37% (32 of 86) of the tumors analyzed. Gene amplification of HNF3alpha was detected in 2 of the 5 overexpressed lung tumors examined. This is the first report of HNF3alpha amplification, and overexpression in esophageal and lung adenocarcinomas. Amplification of HNF3alpha in esophageal and lung tumors may suggest a potential oncogenic role for this gene in tumorigenesis.

Adenocarcinoma↗
PubMed2002

Congenital hydrocephalus associated with congenital glaucoma and natal teeth.

We report the first described association of natal teeth with congenital hydrocephalus and congenital glaucoma, anterior segment dysgenesis with non-attachment of the retina. The clinical findings support a diagnosis of Walker-Warburg syndrome. The forkhead 7 transcription factor gene is proposed as a candidate gene for this syndrome.

Abnormalities, Multiple↗
PubMed2003

The lethal effects of pharmacological cyclin-dependent kinase inhibitors in human leukemia cells proceed through a phosphatidylinositol 3-kinase/Akt-dependent process.

The impact of disruption of the PI3K (phosphatidylinositol 3-kinase) pathway on the response of human leukemia cells to pharmacological cyclin-dependent kinase (CDK) inhibitors has been examined. Exposure of U937 monocytic leukemia cells to minimally toxic concentrations of flavopiridol (FP), roscovitine, or CGP74514A for 3 h in conjunction with the PI3K inhibitor LY294002 (abbreviated LY in the article) resulted in a marked decrease in Akt phosphorylation. Coexposure of cells to LY and CDK inhibitors also resulted in an early (i.e., within 3 h) and striking increase in mitochondrial damage [e.g., cytochrome c, second mitochondria-derived activator of caspases/direct inhibitor of apoptosis (IAP)-binding protein with low isoelectric point (Smac/DIABLO), and apoptosis-initiating factor (AIF) release], caspase activation, and apoptosis. Similar interactions were observed in a variety of other leukemia cell types (e.g., HL-60, Jurkat, Raji, and NB4). Apoptosis, induced by FP/LY, was substantially blocked by ectopic expression of Bcl-2, but to a considerably lesser extent by dominant-negative caspase-8. FP-induced apoptosis was not enhanced by agents that inhibited protein kinase (PK) A (H89), PKC (GFX), mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK1/2; U0126), p38 MAP kinase (MAPK; SB202190), m-target of rapamycin (TOR; rapamycin), or ataxia-telangiectasia mutation (ATM; caffeine), whereas the PI3K inhibitor wortmannin exerted effects similar to those of LY. The dramatic potentiation of CDK inhibitor-induced apoptosis by LY was accompanied by diminished Bad phosphorylation, induction of Bcl-2 cleavage, and down-regulation of X-linked IAP (XIAP) and Mcl-1. Cells exposed to CDK inhibitors + LY also exhibited reduced phosphorylation of glycogen synthase kinase (GSK)-3, forkhead transcription factor (FKHR), p70(S6K), and ERK, but increased activation of p34(cdc2) and p38 MAPK. LY/CDK inhibitor-treated cells also displayed diminished pRb dephosphorylation on CDK2- and CDK4-specific sites, retinoblastoma protein cleavage, and down-regulation of cyclin D(1). Inducible expression of constitutively active (myristolated) Akt significantly, albeit partially, attenuated apoptosis in Jurkat leukemia cells treated with either FP alone or the combination of FP and LY. Finally, cotreatment with LY and FP resulted in a dramatic increase in apoptosis in primary leukemic blasts obtained from a patient with acute myeloblastic leukemia. Together, these findings suggest that the PI3K/Akt pathway plays a major role in regulating the apoptotic response of human leukemia cells to pharmacological CDK inhibitors and raise the possibility that combined interruption of CDK- and PI3K-related pathways may represent a novel therapeutic strategy in hematological malignancies.

2-Aminopurine↗
PubMedDate not supplied

Multiple roles of the PI3K/PKB (Akt) pathway in cell cycle progression.

As its role in tumor progression emerges, the PI3K/PKB (Akt) pathway presents an appealing cancer therapeutic target. Recent studies have investigated the mechanisms underlying the tumor-promoting effects of this pathway. PKB triggers a network that positively regulates G1/S cell cycle progression through inactivation of GSK3-beta, leading to increased cyclin D1, and inhibition of Forkhead family transcription factors and the tumor suppressor tuberin (TSC2), leading to reduction of p27Kip1. The identification of p21Waf1/Cip1 and p27Kip1 as novel substrates of PKB provided new insights into mechanisms whereby hyperactivation of this lipid signaling pathway may lead to cell cycle deregulation in human cancers. The PI3K pathway may also play a key role in the G2/M transition and its constitutive activation may lead to defects in DNA damage checkpoint control.

Animals↗
PubMedDate not supplied

FHA domain-mediated DNA checkpoint regulation of Rad53.

Saccharomyces cerevisiae Rad53 is a protein kinase central to the DNA damage and DNA replication checkpoint signaling pathways. In addition to its catalytic domain, Rad53 contains two forkhead homology-associated (FHA) domains (FHA1 and FHA2), which are phosphopeptide binding domains. The Rad53 FHA domains are proposed to mediate the interaction of Rad53 with both upstream and downstream branches of the DNA checkpoint signaling pathways. Here we show that concurrent mutation of Rad53 FHA1 and FHA2 causes DNA checkpoint defects approaching that of inactivation or loss of RAD53 itself. Both FHA1 and FHA2 are required for the robust activation of Rad53 by the RAD9-dependent DNA damage checkpoint pathway, while an intact FHA1 or FHA2 allows the activation of Rad53 in response to replication block. Mutation of Rad53 FHA1 causes the persistent activation of the RAD9-dependent DNA damage checkpoint pathway in response to replicational stress, suggesting that the RAD53-dependent stabilization of stalled replication forks functions through FHA1. Rad53 FHA1 is also required for the phosphorylation-dependent association of Rad53 with the chromatin assembly factor Asf1, although Asf1 itself is apparently not required for the prevention of DNA damage in response to replication block.

Cell Cycle Proteins↗
PubMed2003

Distinct functions of Nijmegen breakage syndrome in ataxia telangiectasia mutated-dependent responses to DNA damage.

Phosphorylation of NBS1, the product of the gene mutated in Nijmegen breakage syndrome (NBS), by ataxia telangiectasia mutated (ATM), the product of the gene mutated in ataxia telangiectasia, is required for activation of the S phase checkpoint in response to ionizing radiation (IR). However, NBS1 is also thought to play additional roles in the cellular response to DNA damage. To clarify these additional functions of NBS1, we generated NBS cell lines stably expressing various NBS1 mutants from retroviral vectors. The ATM-dependent activation of CHK2 by IR was defective in NBS cells but was restored by ectopic expression of wild-type NBS1. The defects in ATM-dependent activation of CHK2, S phase checkpoint control, IR-induced nuclear focus formation, and radiation sensitivity apparent in NBS cells were not corrected by expression of NBS1 mutants that lack an intact MRE11 binding domain, suggesting that formation of the NBS1-MRE11-RAD50 complex is required for the corresponding normal phenotypes. Expression of NBS1 proteins with mutated ATM-targeted phosphorylation sites (serines 278 or 343) did not restore S phase checkpoint control but did restore the ability of IR to activate CHK2 and to induce nuclear focus formation and normalized the radiation sensitivity of NBS cells. Expression of NBS1 containing mutations in the forkhead-associated or BRCA1 COOH terminus domains did not correct the defects in radiation sensitivity or nuclear focus formation but did restore S phase checkpoint control in NBS cells. Together, these data demonstrate that multiple functional domains of NBS1 are required for ATM-dependent activation of CHK2, nuclear focus formation, S phase checkpoint control, and cell survival after exposure to IR.

Acid Anhydride Hydrolases↗
PubMed2003

Implication of protein kinase B/Akt and Bcl-2/Bcl-XL suppression by the farnesyl transferase inhibitor SCH66336 in apoptosis induction in squamous carcinoma cells.

The farnesyltransferase inhibitor SCH66336 exhibits antitumor activity in vitro and in vivo; however, its mechanism of action is still unresolved. We found that SCH66336 suppressed growth and induced apoptosis of human head and neck squamous carcinoma cells (HNSCC). SCH66336 suppressed protein kinase B/Akt activity as well as the phosphorylation of the Akt substrates glycogen synthase kinase (GSK)-3 beta, forkhead transcription factor, and BAD. Infection of SqCC/Y1 cells with an adenovirus that contained a constitutively active form of Akt rescued cells from SCH66336-induced apoptosis. These results suggest that SCH66336 is a potent apoptosis inducer in HNSCC cells and that it may act by suppressing the Akt pathway.

Alkyl and Aryl Transferases↗
PubMed2003

Identification and characterization of human LL5A gene and mouse Ll5a gene in silico.

ARCN1, KIAA0638, TREH, DDX6, BLR1, BCL9L, UPK2, DLNB13, DLNB14, RPS25, SBDN, G6PT1, HYOU1, VPS11, HMBS, H2AFX, DPAGT1, KIAA0285, MIZF, ABCG4, NOD9, PDZK2, CBL, MCAM, RNF26, C1QTNF5, MFRP, USP2, THY1, and PVRL1 genes are located within the commonly deleted region of neuroblastoma at human chromosome 11q23.3. Here, we characterized the KIAA0638 gene within the 11q23.3 region by using bioinformatics. Because human KIAA0638 gene was homologous to human LL5B gene encoding LL5beta protein, KIAA0638 was designated LL5A gene encoding LL5alpha protein. LL5A isoform 1 (FLJ00141 type) consists of exons 1-12, 14-21 and 23, while LL5A isoform 2 (KIAA0638 type) consists of exon 1-23. LL5A isoform 1 was the major transcript among LL5A isoforms generated due to alternative splicing. Nucleotide sequence of mouse Ll5a cDNA was determined by assembling CB522359 EST and 5'-truncated mKIAA0638 cDNA. Human LL5alpha isoform 2 showed 94.4 and 35.9% total-amino-acid identity with mouse Ll5alpha and human LL5beta, respectively. LL5alpha proteins consist of Forkhead associated (FHA) domain, bipartite nuclear localization signal (NLS), Chromosome segregation ATPases (SMC) domain, and Pleckstrin homology (PH) domain. LL5alpha proteins were homologous to PtdIns(3,4,5)P3 sensor protein LL5beta in the SMC and PH domains, and were also homologous to KIF1A, KIF1B, KIF13A, KIF13B, KIF14, and SNX23 proteins in the FHA domain. LL5alpha protein might be a transducer of PtdIns(3,4,5)P3 levels to the intracellular trafficking system.

Alternative Splicing↗
PubMed2003

[Signal transduction and development of drug for brain ischemic insult].

The author reported that sodium orthovanadate rescues cells from delayed neuronal death in gerbil hippocampus after transient forebrain ischemia though phosphatidylinositol 3 kinase/Akt pathway. We here demonstrated that the activation of FKHR, a Forkhead transcription factor and a substrate for Akt, precedes the delayed neuronal death in CA1 regions after transient forebrain ischemia. The phosphorylation of FKHR at serine-256 in the CA1 region decreased immediately after reperfusion. The dephosphorylation of FKHR was correlated with the decreased Akt activity. Intracerebroventricular injection of orthovanadate 30 min before ischemia inhibited dephosphorylation of FKHR after reperfusion, and block delayed neuronal death in the CA1 regions. Two days after reperfusion, expression of Fas ligand increased in the CA1 region and the orthovanadate injection inhibited this increased expression. Furthermore, sublethal ischemia gradually and persistently stimulated the phosphorylation of Akt-Ser-473 in the CA1 region after reperfusion. The preceded sublethal ischemia prevented the delayed neuronal death induced by the lethal ischemic conditions. Intracerebroventricular injection of wortmannin before preconditioning blocked both the increased in Akt-Ser-473 phosphorylation and the neuroprotective action of preconditioning. These results suggested that the inactivation of Akt results in the activation of FKHR and, in turn, relates to the expression of Fas ligand in the hippocampal CA1 region after transient forebrain ischemia. The prevention of Akt inactivation by treatment with orthovanadate is a potential therapeutic strategy for neuroprotection in brain ischemic insult. Thus PI3-kinase/Akt pathway and its downstream molecules are potential targets for drug development in the brain ischemic insult.

Animals↗
PubMed2003

[Biochemistry of lifespan extension].

A review of biochemical mechanisms underlying the known approaches to extension of lifespan and/or slowing down of ageing suggests that they all modify balances between generation of active oxygen and carbonyl species and the mechanisms that protect from their damaging effects or repair their consequences. A likely common target of the geroprotector effects of antioxidants, melatonin, and antidiabetic biguanides is the mitochondrial respiratory chain. In biological species that evolved through r-selection (nematodes, fruit flies, mice, and rats), the balance between anabolic/reproductive and self-maintenance/protective functions is the most significant modifiable factor of longevity and ageing. At the molecular level, the pivot of this balance is formed by the forkhead-type transfactors, whereas at the physiological level the balance is determined by dietary calories and physical activity via mechanism in which the central role is played by insuline-like peptides and, also, growth hormone and leptin or their functional analogs. In biological species that evolved through K-selection (higher primates, particularly humans), the latter balance is less important, and the biochemical factors of aging are more refracted through the higher regulatory systems, of which the most significant are catecholaminergic mechanisms of regulation of neuroendocrine-immune interrelationships and the circulatory system. This results in a decreased geroprotector potential of calory restriction and in an increased importance of the optimal physical activity. When these conclusions are compared with demographic data, it comes out that virtually all advances in gerontology may be reduced to maxims of healthy ageing known from extreme antiquity. Under optimal socioeconomic conditions, the chances to approach the documented world record of human longevity (122 years) may be increased by (not to mention getting rid of smoking and other abuses) high physical activity, adequate nutrition enriched in fresh fruits, optimism, and timely treatment of specific diseases. The most important bottleneck in the realization of these reserves is currently the public consciousness rather than the science.

Aging↗
PubMed2004

Analysis of transcriptional regulation of the small leucine rich proteoglycans.

PURPOSE: Small leucine rich proteoglycans (SLRPs) constitute a family of secreted proteoglycans that are important for collagen fibrillogenesis, cellular growth, differentiation, and migration. Ten of the 13 known members of the SLRP gene family are arranged in tandem clusters on human chromosomes 1, 9, and 12. Their syntenic equivalents are on mouse chromosomes 1, 13, and 10, and rat chromosomes 13, 17, and 7. The purpose of this study was to determine whether there is evidence for control elements, which could regulate the expression of these clusters coordinately. METHODS: Promoters were identified using a comparative genomics approach and Genomatix software tools. For each gene a set of human, mouse, and rat orthologous promoters was extracted from genomic sequences. Transcription factor (TF) binding site analysis combined with a literature search was performed using MatInspector and Genomatix' BiblioSphere. Inspection for the presence of interspecies conserved scaffold/matrix attachment regions (S/MARs) was performed using ElDorado annotation lists. DNAseI hypersensitivity assay, chromatin immunoprecipitation (ChIP), and transient transfection experiments were used to validate the results from bioinformatics analysis. RESULTS: Transcription factor binding site analysis combined with a literature search revealed co-citations between several SLRPs and TFs Runx2 and IRF1, indicating that these TFs have potential roles in transcriptional regulation of the SLRP family members. We therefore inspected all of the SLRP promoter sets for matches to IRF factors and Runx factors. Positionally conserved binding sites for the Runt domain TFs were detected in the proximal promoters of chondroadherin (CHAD) and osteomodulin (OMD) genes. Two significant models (two or more transcription factor binding sites arranged in a defined order and orientation within a defined distance range) were derived from these initial promoter sets, the HOX-Runx (homeodomain-Runt domain), and the ETS-FKHD-STAT (erythroblast transformation specific-forkhead-signal transducers and activators of transcription) models. These models were used to scan the genomic sequences of all 13 SLRP genes. The HOX-Runx model was found within the proximal promoter, exon 1, or intron 1 sequences of 11 of the 13 SLRP genes. The ETS-FKHD-STAT model was found in only 5 of these genes. Transient transfections of MG-63 cells and bovine corneal keratocytes with Runx2 isoforms confirmed the relevance of these TFs to expression of several SLRP genes. Distribution of the HOX-Runx and ETS-FKHD-STAT models within 200 kb of genomic sequence on human chromosome 9 and 500 kb sequence on chromosome 12 also were analyzed. Two regions with 3 HOX-Runx matches within a 1,000 bp window were identified on human chromosome 9; one located between OMD and osteoglycin (OGN)/mimecan genes, and the second located upstream of the putative extracellular matrix protein 2 (ECM2) promoter. The intergenic region between OMD and mimecan was shown to coincide with different patterns of DNAse I hypersensitivity sites in MG-63 and U937 cells. ChiP analysis revealed that this region binds Runx2 in U937 cells (mimecan transcript note detectable), but binds Pitx3 in MG-63 cells (expressing high level of mimecan), thereby demonstrating its functional association with mimecan expression. Upon comparing the predictions of S/MARs on the relevant chromosomal context of human chromosomes 9 and 12 and their rodent equivalents, no convincing evidence was found that the tandemly arranged genes build a chromosomal loop. CONCLUSIONS: Twelve of 13 known SLRP genes have at least one HOX-Runx module match in their promoter, exon 1, intron 1, or intergenic region. Although these genes are located in different clusters on different chromosomes, the common HOX-Runx module could be the basis for co-regulated expression.

Animals↗
PubMed2005

Identification and characterization of rat Desert hedgehog and Indian hedgehog genes in silico.

Sonic hedgehog (SHH), Desert hedgehog (DHH) and Indian hedgehog (IHH) bind to Patched family receptors (PTCH1 and PTCH2) to transduce signals to GLI1, GLI2 and GLI3. GLI family transcription factors then activate transcription of Hedgehog target genes, such as FOXE1 and FOXM1 encoding Forkhead-box transcription factors. Hedgehog signaling pathway plays a pivotal role in a variety of human tumors, such as gastric cancer, pancreatic cancer, colorectal cancer, breast cancer, prostate cancer, basal cell carcinoma and brain tumors. Rat orthologs for human DHH and IHH remain to be identified. Here, we identified and characterized rat Dhh and Ihh genes by using bioinformatics. Rat Dhh complete coding sequence (CDS) was determined by assembling nucleotide positions 426397-426963, 429715-429976 and 430244-430898 of the AC114446.3 genome sequence. Rat Ihh complete CDS was determined by assembling nucleotide positions 63433-64033, 66432-66693 and 68242-69169 of AC095777.6 genome sequence. Rat Dhh mRNA was expressed in prostate, duodenum and dorsal root ganglia, while rat Ihh mRNA was expressed in cartilage. Rat Dhh showed 99.7% total-amino-acid identity with mouse Dhh, and 96.5% total-amino-acid identity with human DHH. Rat Ihh and human IHH were shorter than mouse Ihh by 38 amino acids. Rat Ihh showed 97.6% total-amino-acid identity with mouse Ihh and 94.4% total-amino-acid identity with human IHH. Hedgehog family proteins consist of signal peptide, Hedgehog ligand peptide and C-terminal peptide. Hedgehog ligand peptides derived from mammalian Hedgehog family proteins were conserved well, while C-terminal peptides were relatively divergent. The HPLGMXXXXS motif in the C-terminus was conserved in Shh orthologs and Ihh orthologs, but not in Dhh orthologs.

Amino Acid Motifs↗
PubMed2006

A vHNF1/TCF2-HNF6 cascade regulates the transcription factor network that controls generation of pancreatic precursor cells.

Generation of pancreatic precursor cells in the endoderm is controlled by a network of transcription factors. Hepatocyte nuclear factor-6 (HNF6) is a key player in this network, because it controls the initiation of the expression of pancreatic and duodenal homeobox 1 (Pdx1), the earliest marker of pancreatic precursor cells. To further characterize this network, we have investigated how the expression of HNF6 is controlled in mouse endoderm, by using in vitro and in vivo protein-DNA interaction techniques combined with endoderm electroporation, transgenesis, and gene inactivation in embryos. We delineated Hnf6 regulatory regions that confer expression of a reporter gene in the embryonic endoderm but not in extraembryonic visceral endoderm. HNF6 expression in the embryonic endoderm was found to depend on an intronic enhancer. This enhancer contains functional binding sites for the tissue-specific factors of the forkhead box A and HNF1 families. Among the latter, variant HNF1 (vHNF1)/TCF2, which is expressed before HNF6 in the endoderm, was found to be critical for HNF6 expression. Therefore, the sequential activation of vHNF1, HNF6, and Pdx1 in the endoderm appears to control the generation of pancreatic precursors. This cascade may be used to benchmark in vitro differentiation of pancreatic precursor cells from embryonic stem cells, for cell therapy of diabetes.

Animals↗
PubMed2005

Screening of growth- or development-related genes by using genomic library with inducible promoter in Aspergillus nidulans.

Using the genomic library constructed at the downstream of the niiA promoter, which induces the over-expression of an inserted DNA fragment, we have attempted to screen the genes affecting growth or development by over-expression. The wild-type strain was transformed using the AMA-niiA(p) library and cultured on 1.2 M sorbitol media, in which asexual sporulation is induced, but sexual development is repressed. Over 100,000 strains transformed to pyrG(+) were analyzed with regard to any changes in phenotype. Consequently, seven strains were isolated for further analyses. These strains were designated NOT [niiA(p) over-expression transformants] stains. Four of the strains were of the inducible type, and the remaining strains were of the multi-copy suppression type. Two of the inducible-type strains, NOT1 and NOT40, harbored genes which had been inserted in reverse direction, suggesting that the mutant phenotypes had been derived from an excess amount of anti-sense mRNA. Domain analyses of the deduced polypeptides from the DNA fragments rescued from the transformants revealed that NOT1, NOT40 and NOT6 harbored a LisH motif, a forkhead domain, and a Zn(II)(2)Cys(6) binuclear zinc cluster, respectively.

Amino Acid Sequence↗
PubMed2007

Relationship of aberrant DNA hypermethylation of CHFR with sensitivity to taxanes in endometrial cancer.

The relationship of aberrant DNA hypermethylation of cell cycle checkpoint genes with the sensitivity of cancer cells to anticancer drugs is a question of current interest. In this study, we investigated the relationship between aberrant hypermethylation of the CHFR (checkpoint with forkhead-associated and ring finger) mitotic checkpoint gene and sensitivity to taxanes in endometrial cancer. Methylation-specific PCR (MSP) indicated aberrant hypermethylation of CHFR in 12.0% (6/50) of endometrial cancer specimens, and suggested that aberrant hypermethylation is significantly more frequent in poorly differentiated adenocarcinoma (G3) (p<0.05). Of six culture cell lines, SNG-II and HEC108 cells showed aberrant hypermethylation and reduced expression of CHFR. These cells had high sensitivity to taxanes but became resistant after demethylation. Cancer specimens with aberrant hypermethylation of CHFR also exhibited high sensitivity to taxanes. To our knowledge, this study is the first to examine aberrant hypermethylation of CHFR in endometrial cancer, and our results suggest that the methylation status of CHFR may be a new molecular index that will allow design of personalized treatment in endometrial cancer. This may be particularly important in poorly differentiated adenocarcinoma (G3), which is known to have a poor prognosis.

Adult↗
PubMed2003

Nitric oxide suppression triggers apoptosis through the FKHRL1 (FOXO3A)/ROCK kinase pathway in human breast carcinoma cells.

BACKGROUND: The winged helix/forkhead transcriptional factor FKHRL1 (FOXO3a) triggers apoptosis, but its mode of action is not well understood. ROCK kinase is an effector molecule in human breast carcinoma cell apoptosis, but its relation to FKHRL1 is unknown. Because the human breast carcinoma T47D cell line releases a great amount of nitric oxide (NO), I investigated signaling of FKHRL1/ROCK [corrected] kinase during NO suppression. METHODS: Expression of phosphorylated FKHRL1 in T47D cells was analyzed using Western blotting. Apoptosis was evaluated by flow cytometry. Transfection of FKHRL1-HA wild-type and mutant FKHRL1-HA T32A constructs were performed by lipofectamine plus reagent. Measurement of NO generation was performed by Griess reaction. RESULTS: Nitric oxide suppression promotes FKHRL1 thr-32-enhanced phosphorylation, which was significantly (P < 0.005) sensitive to Y-27632, a specific inhibitor of the ROCK kinase, but not to capase-3 inhibitor or wortnannin, a specific inhibitor of phosphoinositol-3-OH kinase (PI3K). Nitric oxide suppression by N-(G)-monomethyl-L-arginine, an inhibitor of NO synthase, causes a significant (P < 0.001) increase in the apoptosis of T47D cells. However, a significant decrease (P < 0.01) in NO generation and a significant (P < 0.01) increase in apoptosis were observed when FKHRL1-HA wild-type cells were transfected, which caused increased FKHRL1 thr-32 phosphorylation. CONCLUSIONS: This novel unknown phenomenon of breast carcinoma cell apoptosis was triggered by NO suppression, which promotes FKHRL1 thr-32-enhanced phosphorylation and initiates signaling of FKHRL1 to ROCK kinase as an effector molecule. This apoptotic signalling process is caspase-3 as well as PI3K/Akt independent.

Apoptosis↗
PubMed2002

Effects of aging and caloric restriction on the gene expression of Foxo1, 3, and 4 (FKHR, FKHRL1, and AFX) in the rat skeletal muscles.

In C. elegans, insulin-like hormone signal pathway plays a significant role in longevity. In particular, daf-16 gene product is indispensable factor for this lifespan-extension. This signal pathway is critical for dauer formation, which is a similar state to hibernation in mammals. We examined the expression level of mammalian daf-16 homologues, Foxo 1,3, and 4 (FKHR, FKHRL1, and AFX) mRNAs in the rat skeletal muscles during aging and in 30% caloric restricted of ad libitum fed. The expression level of AFX mRNA was significantly higher at 6 and 12 months than at 3 and 26 months, and FKHRL1 expression was significantly higher at 6 months than at 3 and 26 months but FKHR expression showed no significant change with age. We observed a characteristic expression of AFX and FKHR mRNAs to be significantly higher in the second day in caloric restriction by every-other-day feeding than in ad libitum fed. This suggests that caloric restriction may increase the expression of FKHR-family genes and prevent the aging process in the skeletal muscles.

Aging↗