PubMed Health⌕ Search

Biomedical subjects

I Panagopoulos

Publications and source records attributed to I Panagopoulos.

At least 19 recordsLinked to original sources
PubMed1999

Fusion of the RBP56 and CHN genes in extraskeletal myxoid chondrosarcomas with translocation t(9;17)(q22;q11).

Although most extraskeletal myxoid chondrosarcomas (EMC) are cytogenetically characterized by the translocation t(9;22)(q22;q12), another subset has recently been identified carrying a t(9;17)(q22;q11). Whereas the t(9;22) is known to result in fusion of the CHN (TEC) gene from 9q22 with the EWS gene from 22q12, creating a chimeric EWS/CHN, the genes involved in the t(9;17) of EMC are unknown. We examined two EMC with t(9;17)(q22;q11) and found that the CHN gene was recombined with the RBP56 gene from 17q11 to generate a chimeric RBP56/CHN. RBP56 has not previously been shown to be involved in tumorigenesis but it encodes a putative RNA-binding protein similar to the EWS and FUS (TLS) proteins known to play a pathogenetic role in several sarcomas. The presence of the RBP56/CHN chimeric gene in EMC with t(9;17)(q22;q11) shows that the N-terminal parts of EWS and RBP56 have similar oncogenic potential making them pathogenetically equivalent in oncoproteins arising from fusions with certain transcription factors.

Amino Acid Sequence↗
PubMed1999

Identification of genes differentially expressed in TLS-CHOP carrying myxoid liposarcomas.

Myxoid liposarcomas (MLS) carry a t(12;16) or, more rarely, a t(12;22) resulting in fusion of the transcription factor gene CHOP on chromosome 12 with TLS/FUS on chromosome 16 or EWS on chromosome 22. The chimeric TLS-CHOP or EWS-CHOP proteins most probably function as abnormal transcription factors, causing transcriptional de-regulation of several target genes and relaxation of functions critical for growth and differentiation control. A PCR-based subtractive hybridization technique was used to identify genes that are differentially expressed in TLS-CHOP-carrying MLS but not in normal fat tissue. Six myxoid-liposarcoma-associated transcripts, MLAT, were isolated. The genes identified as MLAT can be divided into 2 groups. MLAT1, 2 and 6 show high similarity to glia-derived nexin, neuronatin and the RET oncogene, respectively, all normally involved in development of tissues of neural origin. MLAT3 to MLAT5 represent new genes.

CCAAT-Enhancer-Binding Proteins↗
PubMed1999

A novel PCR-based approach for the detection of the Huntington disease associated trinucleotide repeat expansion.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder associated with expansions of an unstable CAG trinucleotide repeat in exon 1 of the IT15 gene. In normal individuals, IT15 contains up to 35 CAG repeats, while in affected the repeat length is >36. Polymerase chain reaction (PCR) is used to estimate the number of CAG repeats but may be inefficient in long repeats because of the high C+G content of the HD locus. We present a novel PCR approach for the diagnosis of HD, which permits direct visualization of the amplified products on agarose gel, using ethidium bromide. It is based on the methylation-sensitive conversion of C residues to U by bisulfite treatment of single-stranded DNA and subsequent amplification of the sense strand with specific primers. The bisulfite treatment dramatically reduces the C + G content of the region; thus, the high Tm and stable secondary structures are no longer obstacles to PCR. In both normal and affected individuals, UAG repeats (5'- CAG-3', before bisulfite treatment) in the sense strand can easily be amplified and visualized on a gel by ethidium bromide staining. The method has considerable advantages compared with other described PCR-based diagnostic tests for HD.

Base Sequence↗
PubMed1999

A methylation PCR approach for detection of fragile X syndrome.

Fragile X syndrome is associated with the expansion of the number of CGG trinucleotide tandem repeats at the 5' untranslated region of the FMR1 gene. The number of CGG trinucleotide repeats in normal individuals ranges between 5 and 50, in asymptomatic carrier individuals it ranges between 50 and 200, and in affected individuals it is more than 200 CGG repeats. In addition, in affected individuals the cytosine residues in the CGG repeats and the adjacent CpG island are methylated and the FMR1 gene is transcriptionally inactive. The most common diagnostic method for the detection of the syndrome is Southern blot analysis. Methods based on the polymerase chain reaction (PCR) could facilitate the rapid screening of large numbers of individuals by accurately determining the number of CGG repeats. Current PCR techniques for amplification of CGG repeats are, however, inefficient and unreliable because of their 100% C+G composition. Thus, most of the described PCR protocols require subsequent Southern blot analysis and autoradiography. We present a novel PCR approach for the diagnosis of fragile X syndrome based on the methylation-sensitive conversion of C residues to U by bisulfite on single-strand DNA and subsequent amplification of the antisense strand with specific primers. A PCR with primers for methylated C residues will amplify the CpG dinucleotide region upstream to CGG repeats exclusively in affected males. As a result of extensive mismatch between primers and bisulfite-treated DNA, no PCR fragments will be obtained in normal and transmitting males. Moreover, the bisulfite treatment dramatically reduces the C+G component of the region; thus, the high Tm and the strong secondary structures are no longer obstacles for PCR amplification. In normal and carrier individuals, UUG repeats (previously 3'-CCG-5') in the antisense strand can easily be amplified and visualized on a gel by ethidium bromide staining. We applied our method on 25 males previously diagnosed by Southern blot analysis. All the samples were easily and accurately diagnosed. The method has considerable advantages compared with other diagnostic tests for fragile X syndrome.

Base Sequence↗
PubMed1998

Expression analysis and chromosomal mapping of a novel human gene, APRIL, encoding an acidic protein rich in leucines.

Clone 120041 was selected from the EST database for sequence similarity to DEK and SET proteins rearranged in leukemias. The ends of the cDNA were isolated by RACE technique. The assembled cDNA encodes an LRR-containing protein of 251 amino acids designated APRIL (acidic protein rich in leucines). APRIL has high similarity to human pp32, also named PHAPI (bovine I[PP2A]1), and to rat LANP, respectively. APRIL shows tissue-specific expression as shown by Northern blot analysis. It was localized to 15q25 by FISH.

Amino Acid Sequence↗
PubMed1997

Characterization and chromosomal mapping of the human TFG gene involved in thyroid carcinoma.

Homology searches in the Expressed Sequence Tag Database were performed using SPYGQ-rich regions as query sequences to find genes encoding protein regions similar to the N-terminal parts of the sarcoma-associated EWS and FUS proteins. Clone 22911 (T74973), encoding a SPYGQ-rich region in its 5' end, and several other clones that overlapped 22911 were selected. The combined data made it possible to assemble a full-length cDNA sequence. This cDNA sequence is 1677 bp, containing an initiation codon ATG, an open reading frame of 400 amino acids, a poly(A) signal, and a poly(A) tail. We found 100% identity between the 5' part of the consensus sequence and the 598-bp-long sequence named TFG. The TFG sequence is fused to the 3' end of NTRK1, generating the TRK-T3 fusion transcript found in papillary thyroid carcinoma. The cDNA therefore represents the full-length transcript of the TFG gene. TFG was localized to 3q11-q12 by fluorescence in situ hybridization. The 3' and the 5' ends of the TFG cDNA probe hybridized to a 2.2-kb band on Northern blot filters in all tissues examined.

Amino Acid Sequence↗
PubMed1997

Additional evidence of a variant translocation t(12;22) with EWS/CHOP fusion in myxoid liposarcoma: clinicopathological features.

It is well established that the majority of myxoid/round cell liposarcomas (LPS) are characterized by a reciprocal translocation t(12;16)(q13;p11) which at the molecular level results infusion of the CHOP and FUS/TLS genes. It is assumed that functional characterization of these genes may provide insight into the molecular pathogenesis of this tumour type. This study describes two new cases of myxoid/round cell LPS having a t(12;22). By reverse transcription-polymerase chain reaction (RT-PCR) it has been shown that this leads to fusion between the CHOP and EWS genes, thus indicating involvement of the EWS gene, at least occasionally, in yet another sarcoma type. Combining these two cases with two others which were recently similarly characterized at the molecular level, their clinicopathological features have been compared with cases having the more usual t(12;16). It was not possible to identify any clinical or pathological differences between these molecular genetic subsets. The relevance or significance of these gene fusion products in myxoid/round cell LPS remains to be determined.

Adult↗
PubMed1997

Variable FHIT transcripts in non-neoplastic tissues.

We used nested reverse transcriptase PCR to investigate the expression of the FHIT gene, a presumptive tumor suppressor gene located in chromosomal band 3p 14.2, in non-neoplastic samples. Multiple transcripts of the FHIT gene were found in peripheral blood lymphocytes, skeletal muscle, and liver of healthy individuals, as well as in a cell line derived from isynovial tissue. The data indicate that variable splicing of the FHIT transcript, leading to deletions of exons and thus anomalous or absent FHIT protein production, occurs frequently in non-neoplastic tissues. Hence, the finding of multiple nonfunctional FHIT transcripts is not tumor-specific and cannot be used as a genetic marker of neoplasia.

Acid Anhydride Hydrolases↗
PubMed1997

Characteristic sequence motifs at the breakpoints of the hybrid genes FUS/CHOP, EWS/CHOP and FUS/ERG in myxoid liposarcoma and acute myeloid leukemia.

We have sequenced the breakpoint regions in one acute myeloid leukemia (AML) with t(16;21)(p11;q22) resulting in the formation of a FUS/ERG hybrid gene and in four myxoid liposarcomas (MLS), three of which had the translocation t(12;16) (q13;p11) and a FUS/CHOP fusion gene and one with t(12;22;20)(q13;q12;q11) and an EWS/CHOP hybrid gene. The breakpoints were localized to intron 7 of FUS, intron 1 of CHOP, an intronic sequence of ERG and intron 7 of EWS. In two MLS cases with t(12;16) and in the AML, the breaks in intron 7 of FUS had occurred close to each other, a few nucleotides downstream from a TG dinucleotide repeat region. The break in the two MLS had occurred in the same ATGGTG hexamer and in the AML 40 nucleotides upstream from the hexamer. The third case of t(12;16) MLS had a break upstream and near a TC-dinucleotide repeat region and a sequence similar to the chi bacterial recombination element was found to flank the breakpoint. In the MLS with the EWS/ CHOP hybrid gene, the break in intron 7 of EWS had occurred close to an Alu sequence. Similarly, in all 4 MLS, the breaks in intron 1 of CHOP were near an Alu sequence. No Alu or other repetitive sequences were found 250 bp upstream or downstream from the break in the ERG intron involved in the AML case. In the AML, the MLS with ESW/CHOP and in one MLS with FUS/CHOP there were one, two and six, respectively, nucleotide identity between the contributing germline sequences in the breakpoint. In the other two MLS cases, two and three extra nucleotides of unknown origin were inserted between the FUS and CHOP sequences. At the junction and/or in its close vicinity, identical oligomers, frequently containing a trinucleotide TGG, were found in both partner genes. Our data thus show that all four genes-FUS, EWS, CHOP and ERG-contain characteristic motifs in the breakpoint regions which may serve as specific recognition sites for DNA-binding proteins and have functional importance in the recombination events taking place between the chromosomes. Different sequence motifs may, however, play a role in each individual case.

Acute Disease↗
PubMed1996

The FHIT and PTPRG genes are deleted in benign proliferative breast disease associated with familial breast cancer and cytogenetic rearrangements of chromosome band 3p14.

We have used nested reverse transcription-PCR (RT-PCR) and PCR on genomic DNA to search for aberrations in the FHIT and PTPRG genes, both located in chromosomal band 3p14.2, in specimens from cytogenetically analyzed benign breast lesions (three samples with atypical hyperplasia and one with fibroadenosis) from two women belonging to breast cancer families. The transcription analysis showed that the FHIT gene was either not expressed or that its expression was dramatically reduced to a level not detectable by nested RT-PCR in the samples with atypical hyperplasia. Genomic analysis of exons 3 and 5 of FHIT and exon 12 of PTPRG provided evidence that these DNA segments were homozygously deleted in the majority of the cells. These data are in line with the histopathological features and cytogenetic findings in the three samples; none contained normal parenchyma, and all had chromosomal aberrations involving band 3p14. RT-PCR analysis of the fibroadenosis specimen, which had a normal karyotype, detected the expected 856-bp fragment as well as an additional alternative transcript variant of FHIT with 1014 bp. The additional 158-bp sequence, which may add 38 amino acids to the NH2-terminal part of the previously described FHIT protein, was inserted between exons 4 and 5 and seems to be a new exon located in intron 4 of FHIT.

Acid Anhydride Hydrolases↗
PubMed1996

Expression patterns of the human sarcoma-associated genes FUS and EWS and the genomic structure of FUS.

FUS (TLS) was first identified as the 5'-part of a fusion gene with CHOP (GADD153, DDIT3) in myxoid liposarcomas with t(12; 16)(q13; p11). Homologies were found with the EWS oncogene, which is rearranged in Ewing sarcomas and other neoplasias. The genomic structure of FUS shows extensive similarities with that of EWS, but the exon/intron structures differ in the 5' parts, and overall FUS is smaller than EWS. Exon 3 of FUS corresponds to exons 3 and 4 in EWS. FUS exons 4-6 correspond to EWS exons 5-8. Exons 7 to 15 of FUS are very similar to those in EWS, although the EWS exons are larger than the corresponding FUS exons. FUS and EWS were expressed in all tissues investigated. The transcripts were stable within the 160-min half-life experiments. No or little variation in FUS or EWS expression was seen when resting lymphocytes were activated. These observations indicate that FUS and EWS belong to the housekeeping type of genes. This view is supported by the presence of the housekeeping gene type of promoter region in both genes.

Amino Acid Sequence↗
PubMed1996

Fusion of the EWS and CHOP genes in myxoid liposarcoma.

The translocation t(12;16)(q13;p11), which cytogenetically characterizes myxoid liposarcomas (MLS), results in a fusion of the CHOP gene in 12q13 and the FUS gene in 16p11, creating a chimeric FUS/CHOP gene. We have identified two cases of MLS with translocations giving rise to recombination between 12q13 and 22q12. The result was a fusion of the N-terminal part of the EWS gene in 22q12, involved in a number of mesenchymal tumor types, with the CHOP gene and the creation of an EWS/CHOP chimeric gene. The presence of the EWS/CHOP chimeric gene in MLS shows that (i) the N-terminal part of FUS may be replaced by the N-terminal part of EWS in a CHOP fusion oncoprotein (ii) the two N-terminal parts, when fused to certain transcription factors, have a common or very similar oncogenic potential and (iii) the tumorigenic process in MLS and the morphogenetically distinctly different EWS-associated tumor types may be related.

Amino Acid Sequence↗
PubMed1996

Genomic PCR detects tumor cells in peripheral blood from patients with myxoid liposarcoma.

Myxoid liposarcoma (MLS) is the most common subtype of liposarcoma. The cytogenetic hallmark of MLS is the pathognomonic t(12;16)(q13;p11), present in more than 85% of cases. The translocation leads to the fusion of the CHOP and FUS genes at 12q13 and 16p11, respectively, and the generation of a FUS/CHOP hybrid protein. The presence of a tumor-specific chimeric gene makes it possible to identify MLS cells by polymerase chain reaction (PCR). We have analyzed peripheral blood samples obtained during a 10-year period at diagnosis of primary and/or recurrent disease in 19 MLS patients with t(12;16) and in one MLS patient with t(12;22;20), resulting in the fusion of the CHOP and EWS genes. Nested PCR on genomic DNA from blood samples amplified FUS/CHOP hybrid fragments in three patients and EWS/CHOP in the patient with t(12;22;20). There was no obvious association between PCR findings and clinical outcome, but larger series are needed to draw any firm conclusions.

Adult↗
PubMed1995

Cloning and sequencing of a cDNA encoding rat D-dopachrome tautomerase.

An enzyme which converts D-dopachrome into 5,6-dihydroxyindole has recently been isolated from rat liver. Enzymatic D-dopachrome conversion has been observed in extracts from all tissues examined of several species, including man. We have now cloned and sequenced a 628 bp long cDNA encoding the enzyme provisionally called D-dopachrome tautomerase. The cDNA was isolated by 3' and 5' rapid amplification and cloning of cDNA ends (RACE) from rat liver cells using degenerate oligonucleotide primers, deduced from the N-terminal peptide sequence of D-dopachrome tautomerase. The cDNA contains an open reading frame encoding 118 amino acids. Edman degradation of intact and of trypsin degraded D-dopachrome tautomerase fragments gave information on and corroborated 67% of the deduced protein sequence. A homology search in the EST database found a human cDNA encoding a peptide sharing 66% homology with the rat enzyme. The rat D-dopachrome tautomerase shares 27% homology with the rat macrophage migration inhibitory factor (MIF).

Amino Acid Sequence↗
PubMed1995

Two distinct FUS breakpoint clusters in myxoid liposarcoma and acute myeloid leukemia with the translocations t(12;16) and t(16;21).

The FUS gene, which maps to 16p11, is fused to the CHOP gene in the t(12;16) (q13;p11) that characterizes myxoid liposarcomas (MLS) and to the ERG gene in acute myeloid leukemia (AML) with t(16;21) (p11;q22). In the present study we have mapped the breakpoints within FUS in 13 MLS with t(12;16) and in one AML with t(16;21). This region of FUS is about 3.9 kb and contains four exons. The breakpoints clustered to two zones (1 and 2). A strong association was found between the two known types of FUS/CHOP transcripts and the genomic localization of the breakpoints. In all cases expressing only type I or both type I and II FUS/CHOP transcript the genomic breakpoints mapped to zone 1. In all cases expressing only the type II transcript the breakpoints occurred in zone 2. The breakpoint in the AML case was in zone 1, suggesting that in-frame fusion transcripts are selected by similar mechanisms in both MLS and AML.

Base Sequence↗
PubMed1994

Characterization of the CHOP breakpoints and fusion transcripts in myxoid liposarcomas with the 12;16 translocation.

Myxoid liposarcomas are cytogenetically characterized by t(12;16)(q13;p11). The translocation results in rearrangements of the CHOP gene in 12q13 and the FUS gene in 16p11, creating a fusion gene where the RNA-binding domain of FUS is replaced by the DNA-binding and leucine zipper dimerization domain of CHOP. In the present study, we have mapped 16 genomic breakpoints in the region of the CHOP gene and isolated and sequenced a new variant (type II) of the chimeric FUS/CHOP transcript. The genomic breakpoints were dispersed along a 7.50-kilobase pair region from a SstI cleavage site upstream of the promoter of CHOP to a PstI cleavage site within intron 1. Reverse transcriptase-polymerase chain reaction analysis of tumor samples demonstrated the presence of two variant fragments, 654 base pairs (type I) and 378 base pairs (type II) in size. Of the 13 samples analyzed, 7 showed the smaller, 3 showed the larger, and 3 showed both types of transcripts. We cloned and sequenced the two fragments and found in type II a novel fusion point in the FUS mRNA 275 base pairs upstream of that present in the type I transcript. In both types of transcripts the interrupted FUS is followed by the entire exon 2 of CHOP. As a consequence the normally nontranslated exon 2 is translated and in both types there is in the junction between FUS and CHOP a shift from a FUS glycine codon to a valine codon in the chimeric mRNA.

Base Sequence↗
PubMed1994

Fusion of the FUS gene with ERG in acute myeloid leukemia with t(16;21)(p11;q22).

It has been shown that the gene ERG in 21q22 is rearranged in the t(16;21)(p11;q22) associated with acute myeloid leukemia (AML). ERG is a member of the ETS gene family and is fused with EWS in a subset of Ewing's sarcomas. EWS in 22q12 has a very high homology with FUS (also called TLS) in 16p11; the latter gene is rearranged in the t(12;16)(q13;p11) that characterizes myxoid liposarcoma. To investigate whether FUS is involved in the t(16;21) of AML, we used the Southern blot technique and polymerase chain reaction (PCR) to examine the bone marrow of a 3-year-old boy with a t(16;21)(p11;q22)-positive AML. Hybridization of Southern blot filters containing digested DNA with probes for FUS and ERG showed both germline and aberrant fragments. Using specific primers for the 5' part of FUS and the 3' part of ERG, we amplified a 4.4 kb genomic FUS/ERG DNA fragment from the leukemic sample. In a second PCR experiment, in which we used primers upstream of the 5' part of ERG and downstream of the 3' part of FUS, a 5.6 kb fragment was amplified. Blotting and hybridization with specific probes for FUS and ERG revealed that the amplified fragments consisted of FUS/ERG and ERG/FUS hybrid DNA. Both PCR fragments, when used as probes, detected germline ERG and FUS as well as aberrant fragments on Southern blot filters. The results suggest that the t(16;21) in AML leads to rearrangement and fusion of the FUS and ERG genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗