Methylation of eukaryotic elongation factor 2 induced by basic fibroblast growth factor via mitogen-activated protein kinase

Protein arginine methylation is important for a variety of cellular processes including transcriptional regulation, mRNA splicing, DNA repair, nuclear/cytoplasmic shuttling and various signal transduction pathways. However, the role of arginine methylation in protein biosynthesis and the extracellular signals that control arginine methylation are not fully understood. Basic fibroblast growth factor (bFGF) has been identified as a potent stimulator of myofibroblast dedifferentiation into fibroblasts. We demonstrated that symmetric arginine dimethylation of eukaryotic elongation factor 2 (eEF2) is induced by bFGF without the change in the expression level of eEF2 in mouse embryo fibroblast NIH3T3 cells. The eEF2 methylation is preceded by ras-raf-mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK1/2)-p21(Cip/WAF1) activation, and suppressed by the mitogen-activated protein kinase (MAPK) inhibitor PD98059 and p21(Cip/WAF1) short interfering RNA (siRNA). We determined that protein arginine methyltransferase 7 (PRMT7) is responsible for the methylation, and that PRMT5 acts as a coordinator. Collectively, we demonstrated that eEF2, a key factor involved in protein translational elongation is symmetrically arginine-methylated in a reversible manner, being regulated by bFGF through MAPK signaling pathway.

Methylation of eukaryotic elongation factor 2 induced by basic fibroblast growth factor via mitogen-activated protein kinase

Protein arginine methylation is important for a variety of cellular processes including transcriptional regulation, mRNA splicing, DNA repair, nuclear/cytoplasmic shuttling and various signal transduction pathways. However, the role of arginine methylation in protein biosynthesis and the extracellular signals that control arginine methylation are not fully understood. Basic fibroblast growth factor (bFGF) has been identified as a potent stimulator of myofibroblast dedifferentiation into fibroblasts. We demonstrated that symmetric arginine dimethylation of eukaryotic elongation factor 2 (eEF2) is induced by bFGF without the change in the expression level of eEF2 in mouse embryo fibroblast NIH3T3 cells. The eEF2 methylation is preceded by ras-raf-mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK1/2)-p21(Cip/WAF1) activation, and suppressed by the mitogen-activated protein kinase (MAPK) inhibitor PD98059 and p21(Cip/WAF1) short interfering RNA (siRNA). We determined that protein arginine methyltransferase 7 (PRMT7) is responsible for the methylation, and that PRMT5 acts as a coordinator. Collectively, we demonstrated that eEF2, a key factor involved in protein translational elongation is symmetrically arginine-methylated in a reversible manner, being regulated by bFGF through MAPK signaling pathway.

Mutation analysis of p31(comet) gene, a negative regulator of Mad2, in human hepatocellular carcinoma

Failure of mitotic checkpoint machinery leads to the chromosomal missegregation and nuclear endoreduplication, thereby driving the emergence of aneuploidy and tetraploidy population. Although abnormal nuclear ploidy and the resulting impairment of mitotic checkpoint function are typical physiological event leading to human hepatocellular carcinoma, any mutational change of mitotic checkpoint regulators has not yet been discovered. Therefore, we investigated the mutation of p31(comet), a recently identified mitotic checkpoint regulator, in human hepatocellular carcinoma. Of 51 human hepatocellular carcinoma tissue and 6 cell lines tested, five samples exhibited nucleotide sequence variations dispersed on four sites within the entire coding sequence. Among these sites with sequence substitutions, three were found to be missense mutation accompanied with amino acid change but one was a silent mutation. Of these sequence substitutions, two were present in both tumor and non-tumor liver tissues, suggesting the possibility of polymorphism. The present findings indicate that p31(comet) does not have an impact on the formation of aneuploidy and tetraploidy found in human hepatocellular carcinoma.

SIRT1 promotes DNA repair activity and deacetylation of Ku70

Human SIRT1 controls various physiological responses including cell fate, stress, and aging, through deacetylation of its specific substrate protein. In processing DNA damage signaling, SIRT1 attenuates a cellular apoptotic response by deacetylation of p53 tumor suppressor. The present study shows that, upon exposure to radiation, SIRT1 could enhance DNA repair capacity and deacetylation of repair protein Ku70. Ectopically over-expressed SIRT1 resulted in the increase of repair of DNA strand breakages produced by radiation. On the other hand, repression of endogenous SIRT1 expression by SIRT1 siRNA led to the decrease of this repair activity, indicating that SIRT1 can regulate DNA repair capacity of cells with DNA strand breaks. In addition, we found that SIRT1 physically complexed with repair protein Ku70, leading to subsequent deacetylation. The dominant-negative SIRT1, a catalytically inactive form, did not induce deacetylation of Ku70 protein as well as increase of DNA repair capacity. These observations suggest that SIRT1 modulates DNA repair activity, which could be regulated by the acetylation status of repair protein Ku70 following DNA damage.

Decreased expression of DNA repair proteins Ku70 and Mre11 is associated with aging and may contribute to the cellular senescence

The gradual loss of telomeric DNA can contribute to replicative senescence and thus, having longer telomeric DNA is generally considered to provide a longer lifespan. Maintenance and stabilization of telomeric DNA is assisted by binding of multiple DNA-binding proteins, including those involved in double strand break (DSB) repair. We reasoned that declining DSB repair capacity and increased telomere shortening in aged individuals may be associated with decreased expression of DSB repair proteins capable of telomere binding. Our data presented here show that among the DSB repair proteins tested, only the expression of Ku70 and Mre11 showed statistically significant age-dependent changes in human lymphocytes. Furthermore, we found that expressions of Ku70 and Mre11 are statistically correlated, which indicate that the function of Ku70 and Mre11 may be related. All the other DSB repair proteins tested, Sir2, TRF1 and Ku80, did not show any significant differences upon aging. In line with these data, people who live in the regional community (longevity group), which was found to have statistically longer average life span than the rest area, shows higher level of Ku70 expression than those living in the neighboring control community. Taken together, our data show, for the first time, that Ku70 and Mre11 may represent new biomarkers for aging and further suggest that maintenance of higher expression of Ku70 and Mre11 may be responsible for keeping longer life span observed in the longevity group.

Increased methylation of the cytosolic 20-kD protein is accompanied by liver regeneration in a hepatectomized rat

Arginine methylation has been implicated in the signal transduction pathway leading to cell growth. Here we show that a regenerating rat liver following partial hepatectomy exhibited elevated methyltransferase activity as shown by increased methylation of a subset of endogenous proteins in vitro. The 20-kDa protein was shown to be a major cytosolic protein undergoing methylation in regenerating hepatocytes. Methylation of the 20-kDa protein peaked at 1 d following partial hepatectomy, which gradually declined to a basal level within the next 14 d. Likewise, methylation of exogenously added bulk histones followed the similar time kinetics as the 20-kDa protein, reflecting time-dependent changes in methyltransferase activity in regenerating hepatocytes. Presence of exogenously added bulk histone in the in vitro methylation assay resulted in dose-dependent inhibition of methylation of the 20-kDa protein. All the histone subtypes tested, histone 1, 2A, 2B, 3 or 4, were able to inhibit methylation of the 20-kDa protein while addition of cytochrome C, a-lactalbumin, carbonic anhydrase, bovine serum albumin, and g globulin minimally affected methylation of the 20-kDa protein. Since methylation of the 20-kDa protein preceded proliferation of hepatocytes upon partial hepatectomy, it is tempting to speculate that the methylated 20-kDa protein by activated histone-specific methyltransferase may be involved in an early signal critical for liver regeneration.

The nuclear 16-kD protein methylation increases in the early period of liver regeneration in a hepatectomized rat

Methylation events play a critical role in various cellular processes including regulation of gene transcription and proliferation. We observed that methyltransferase activity underwent time-dependent changes in the cytosol of the rat hepatocytes upon partial hepatectomy. However, any change in the methylation of nuclear proteins is not clear during hepatocyte proliferation. The nuclear fraction possesses basal level of methyltransferase to catalyze methylation of several proteins ranging from 7 to 70 kD prior to any hepatecmony. The specific p16 (16 kD) band was transiently and heavily methylated post 1 day hepatectomy, and then became non- detectable, but not in the control liver. Methylation of p16 band was completely inhibited by exogenously added histones, particularly 2AS, 1, 2A and 2B subtypes. The methylated p16 protein remains stable in either acid or alkali- induced demethylation conditions, indicating that methylation is not likely to occur on isoaspartyl or C-terminal cysteinyl residues. Exogenous addition of non-hydrolyzable GTP caused a dose- dependent suppression of a p16 methylation suggesting that G-proteins might play a role as an endogenous methylation inhibitor in vivo. Taken together, we have identified the proliferation event associated-methylation of the nuclear p16 protein in the hepatocytes undergoing liver regeneration.

Gene expression profiling of oxidative stress on atrial fibrillation in humans

Atrial Fibrillation (AF) is thought be caused by oxidative stress. Oxidative stress at the cellular level results from many factors, including exposure to alcohol, medications, cold, toxins or radiation. In this study we investigated gene transcriptional profiles on the human myocardial tissues from AF and oxidative stress conditions. Right atrial appendages were obtained from AF patients (n = 26) undergoing the Maze procedure, and from control patients (n = 26) who were in normal sinus rhythm and undergoing coronary artery bypass graft operation. To examine the effects of oxidative stress on AF, we used radioactive complementary DNA (cDNA) microarrays to evaluate changes in the expression of 1,152 known genes. This technology, which monitors thousands of genes simultaneously, gives us a better picture of the interactions between AF and oxidative stress. Total RNAs prepared from the retrieved tissues were used to synthesize(33)P-labeled cDNAs by reverse transcription and hybridized to cDNA microarrays. Gene expression profiles showed that 30 genes were upregulated and 25 were downregulated in AF patients compared with control patients. Moreover, comparison rank analysis revealed that the expression of five genes related to reactive oxygen species (ROS)-including flavin containing monooxygenase 1, monoamine oxidase B, ubiquitin specific protease 8, tyrosinase-related protein 1, and tyrosine 3-monooxygenase-increased by more than 2.0 of the Z-ratio, and two genes related to anti-oxidants including glutathione peroxidase 1, and heme oxygenase 2-decreased to the Z-ratio levels of <= -2.0. Apparently, a balanced regulation of pro- and anti-oxidation can be shifted toward pro-oxidation and can result in serious damage similar to that of human AF. Western blotting analysis confirmed the upregulation of tyrosinase-related protein 1 and tyrosine 3-monooxygenase and the downregulation of heme oxygenase 2. These results suggested that the gene expression pattern of myocardial tissues in AF patients can be associated with oxidative stress, resulting in a significant increase in ROS. Thus, the cDNA microarray technique was useful for investigating transcription profiles in AF. It showed that the intracellular mechanism of oxidative stress plays a pivotal role in the pathologic progression of AF and offers novel insight into potential treatment with antioxidants.

Genome-wide expression profiling of 8-chloroadenosine- and 8-chloro-cAMP-treated human neuroblastoma cells using radioactive human cDNA microarray

Previous reports raised question as to whether 8-chloro-cyclic adenosine 3,5-monophosphate (8-Cl-cAMP) is a prodrug for its metabolite, 8-Cl-adenosine which exerts growth inhibition in a broad spectrum of cancer cells. The present study was carried out to clarify overall cellular affects of 8-Cl-cAMP and 8-Cl-adenosine on SK-N-DZ human neuroblastoma cells by ystematically characterizing gene expression using radioactive human cDNA microarray. Microarray was prepared with PCR-amplified cDNA of 2,304 known genes spotted on nylon membranes, employing (1)P-labeled cDNAs of SK-N-DZ cells as a probe. the expression levels of approximately 100 cDNAs, representing about 8% of the total DNA elements on the array, were altered in 8-Cl-adenosine- or 8-Cl-cAMP-treated cells, respectively. The genome-wide expression of the two samples exhibited partial overlaps; different sets of up-regulated genes but the same set of down-regulated genes. 8-Cl-adenosine treatment up- egulated genes involved in differentiation and development (LIM protein, connexin 26, neogenin, neurofilament triplet L protein and p21( WAF1/CIP1)) and immune response such as natural killer cells protein 4, and down-regulated ones involved in proliferation and transformation (transforming growth factor-beta, DYRK2, urokinase-type plasminogen activator and proteins involved in transcription and translation) which were in close parallel with those by 8-Cl-cAMP. Our results indicated that the two drugs shared common genomic pathways for the down-regulation of certain genes, but used distinct pathways for the up-regulation of different gene clusters. Based on the findings, we suggest that the anti-cancer activity of 8-Cl-cAMP results at least in part through 8-Cl-adenosine. Thus, the systematic use of DNA arrays can provide insight into the dynamic cellular pathways involved in anticancer activities of chemotherapeutics.

Introduction of Radiolabeled Therapeutic Oligonucleotides As Nanonuclear Explosive Gene Therapy / 대한핵의학회잡지

No abstract available.

Partial purification of protein farnesyl cysteine carboxyl methyltransferase from bovine brain

C-terminal farnesyl cysteine carboxyl methylation has been known to be the last step in the post-translational modification processes of several important signal transduction proteins in eukaryotes including ras related GTP binding proteins and the gamma-subunit of heterotrimeric G proteins. Protein farnesyl cysteine carboxyl methyltransferase (PFCCMT; EC, 2.1.1.100) catalyzing the reaction is well characterized as being stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and suppressed by N-acetyl-S-farnesyl-L-cysteine (AFC). As an initial step to understand the physiological significance of the process, we attempted to purify the enzyme, which was partially purified 130-fold (specific activity, 143 pmol of methyl group transferred/min/mg of protein) with yield of 1.8% after purification by fast protein liquid chromatography (FPLC) on a Superdex 75 column. The enzyme was further purified with non denaturing polyacrylamide gel electrophoresis (ND-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of PFCCMT was determined to be about 30 kDa based on Superdex 75 FPLC as well as photoaffinity labelling with S-adenosyl-L-[methyl-3H] methionine ([methyl-3H]SAM). The partially purified enzyme (Superdex 75 eluate) was found to be characteristically affected by GTP gamma S, being activated about 40-fold in 2 mM, in contrast to ATP which did not show any effect on enzyme activity. Meanwhile, the enzyme was found to be markedly inhibited by AFC, reaching 0 activity in 2 mM. These observations strongly suggested that the partially purified enzyme was PFCCMT.

Screening of the Cardiac Beta Myosin Heavy Chain Gene for the Linkage to Familial Hypertrophic Cardiomyopathy in a Korean Family

BACKGROUND: Through a genome-wide search using the genetic markers(RFLP genetic markers), the familial hypertrophic cardiomyopathy(FHCM) with an autosomal dominant mode of inheritance has been firstly detected to be genetically linked to chromosome 14q1. The subsequent studies have shown that the point mutations at the exons encoding for the head and head /rod junction of the cardiac beta myosin heavy chain(beta-MHC) are the most frequent type of mutation in the FHCM families genetically implicated with a linkage to beta-MHC, whereas the alpha/beta-MHC hybrid gene and a large deletion at the 3' region of beta-MHC gene were also rarely detected. With the other families genetically implicated with the chromosomes 1,11,15,16 and 18, FHCM also manifests locus heterogeneity, a phenomenon in which abnormalities at different genes are involved in different families. In addition, a korean FHCM family with 403Arg-->Gln mutation of beta-MHC gene has been previously found by an american research group. METHODS: For clinical diagnosis, echocardiography and electrocardiography were performed on the individual members of a korean FHCM family. The microsatellite markers(MYO-I,MYO-II) located in the beta-MHC gene region were amplified by PCR(polymerase chain reaction) and the polymorphism was analyzed for the possible linkage to the phenotypic expression of FHCM. Independently, the same PCR products of the exons 13 and 23 were digested with the specific restriction enzymes for the presence of the most frequently reported point mutations of beta-MHC gene (403 and 908 amino acid mutations). Single strand conformation polymorphism(SSCP) of the exon 13 and 23 of the beta-MHC gene was also analyzed of the mobility shift expected if any point mutation is present at these two exons. RESULTS: The inheritance pattern of HCM(hypertrophic cardiomyopathy) in the family is considered as autosomal dominant. In this family(KU 101), one of the microsatellite markers(MYO-II) indicated the possible cosegregation between the allele was also present in the 32-year-old brother of the proband, who reveals no clinical signs of the disease. The other microsatellite genetic marker(MYO-I) was uninformative, without giving the discriminating power to verify the linkage to beta-MHC gene. In the analysis for two common mutations of beta-MHC gene by PCR-RFLP and PCR-SSCP, no evidence was found for 403 and 908 amino acid mutations and any point mutation in the exons 13 and 23. CONCLUSIONS: Based on the linkage analysis using microsatellite genetic markers, there was a possibility that the disease could be linked to an abnormality in the beta-MHC gene of the chromosome 14q1.

Screening of the Cardiac Beta Myosin Heavy Chain Gene for the Linkage to Familial Hypertrophic Cardiomyopathy in a Korean Family

BACKGROUND: Through a genome-wide search using the genetic markers(RFLP genetic markers), the familial hypertrophic cardiomyopathy(FHCM) with an autosomal dominant mode of inheritance has been firstly detected to be genetically linked to chromosome 14q1. The subsequent studies have shown that the point mutations at the exons encoding for the head and head /rod junction of the cardiac beta myosin heavy chain(beta-MHC) are the most frequent type of mutation in the FHCM families genetically implicated with a linkage to beta-MHC, whereas the alpha/beta-MHC hybrid gene and a large deletion at the 3' region of beta-MHC gene were also rarely detected. With the other families genetically implicated with the chromosomes 1,11,15,16 and 18, FHCM also manifests locus heterogeneity, a phenomenon in which abnormalities at different genes are involved in different families. In addition, a korean FHCM family with 403Arg-->Gln mutation of beta-MHC gene has been previously found by an american research group. METHODS: For clinical diagnosis, echocardiography and electrocardiography were performed on the individual members of a korean FHCM family. The microsatellite markers(MYO-I,MYO-II) located in the beta-MHC gene region were amplified by PCR(polymerase chain reaction) and the polymorphism was analyzed for the possible linkage to the phenotypic expression of FHCM. Independently, the same PCR products of the exons 13 and 23 were digested with the specific restriction enzymes for the presence of the most frequently reported point mutations of beta-MHC gene (403 and 908 amino acid mutations). Single strand conformation polymorphism(SSCP) of the exon 13 and 23 of the beta-MHC gene was also analyzed of the mobility shift expected if any point mutation is present at these two exons. RESULTS: The inheritance pattern of HCM(hypertrophic cardiomyopathy) in the family is considered as autosomal dominant. In this family(KU 101), one of the microsatellite markers(MYO-II) indicated the possible cosegregation between the allele was also present in the 32-year-old brother of the proband, who reveals no clinical signs of the disease. The other microsatellite genetic marker(MYO-I) was uninformative, without giving the discriminating power to verify the linkage to beta-MHC gene. In the analysis for two common mutations of beta-MHC gene by PCR-RFLP and PCR-SSCP, no evidence was found for 403 and 908 amino acid mutations and any point mutation in the exons 13 and 23. CONCLUSIONS: Based on the linkage analysis using microsatellite genetic markers, there was a possibility that the disease could be linked to an abnormality in the beta-MHC gene of the chromosome 14q1.

Carrier detection of duchenne muscular dystrophy with closelylinked RFLPs / 체질인류학회지

No abstract available.

An experimental study of the electrical stimulation effect on the tendon healing in vitro

No abstract available.

Chromosomal Changes in Transitional Cell Carcinoma of the Bladder (Preliminary Report) / 대한비뇨기과학회지

3 cases of transitional cell carcinoma were subjected to detailed cytogenetic analysis. All three were superficial (T1G I , T1G III, T1G I). Case 1 and case 3 (all T1G I) had diploidy modal chromosomal number but case 2 (TtGIII) had partly triploidy and tetraploidy chromosome. Case 3 showed marker chromosomes and in case 2 and 3, breakage of long arm of the second chromosome was seen.