Effect of irradiation on DNA synthesis, NBN gene expression and chromosomal stability in cells with NBN mutations.

INTRODUCTION: The NBN gene product is part of the MRE11/RAD50/NBN complex, which plays an essential role in genomic stability. In the study we try to answer the question what is the effect of irradiation on DNA synthesis, NBN gene expression and chromosomal stability in cells with homozygous c.657-661del, and heterozygous c.657-661del, p.I171V and p.R215W NBN gene mutations. MATERIAL AND METHODS: Immortalized B-lymphocytes with NBN gene mutations were X-ray irradiated at doses of 1, 2, 5 and 8 Gy/min. Radioresistant DNA synthesis rate and the percentage of cells in phase S was analyzed by 3H thymidine and BrdU incorporation assays. NBN gene expression was quantified by real-time PCR with TaqMan fluorescent probe. RESULTS: Increasing the irradiation dose resulted in gradual decrease of 3H thymidine incorporation in all cells, but significantly only in homo- and heterozygous c.657-661del cells (p-values < 0.0001). After irradiation the relative expression of NBN was significantly higher in homozygous c.657-661del and heterozygous p.R215W cells as compared to heterozygous c.657-661del, p.I171V and control cells (p < 0.01). All cells with NBN gene mutations showed significantly higher total number of chromosomal aberrations per metaphase as compared to control cells, with the highest number of aberrations in homozygous c.657-661del cells (p < 0.001). CONCLUSIONS: The results obtained indicate that homozygous c.657-661del mutation affects cell sensitivity to irradiation. Moreover, homozygous variant is associated with disturbance in the activation of cell cycle checkpoints and with defects in DNA repair. In turn, heterozygous c.657-661del, p.R215W and p.I171V mutations do not substantially alter the radiosensitivity.

Submicroscopic genomic rearrangements change gene expression in T-cell large granular lymphocyte leukemia.

OBJECTIVES: To better understand the molecular pathogenesis of T-cell large granular lymphocyte leukemia (T-LGL), we decided to search for those genetic alterations in T-LGL patients and MOTN-1 cell line (established from T-LGL patient) that have an impact on gene expression and as a result can influence cell biology. METHODS: Multicolor fluorescence in situ hybridization (mFISH) analysis of the MOTN-1 cell line was performed as well as paired-end next-generation sequencing (NGS; Illumina HiSeq2000) of this cell line and one T-LGL patient. In addition, chosen 6q region was characterized in three T-LGL patients using high-resolution comparative genomic hybridization (FT-CGH) and LM-PCR. Gene expression was studied by RNA sequencing (RNAseq; SOLID5500). RESULTS: Rearrangements were detected within 1p and 2q in MOTN-1 affecting expression of FGR, ZEB2, and CASP8, and within 6q in MOTN-1 and one T-LGL patient affecting MAP3K5 and IFNGR1. Nineteen genes, among them FOXN3, RIN3, AKT1, PPP2R5C, were overexpressed as a result of an amplification in 14q in one T-LGL patient. Two novel fusion transcripts were identified: CASP8-ERBB4 in MOTN-1 and SBF1-PKHD1L1 in T-LGL patient. CONCLUSIONS: This study showed that submicroscopic genomic rearrangements change gene expression in T-LGL. Several genes involved in rearrangements were previously linked to cancer and survival pattern that characterizes T-LGL cells.

Identification of multiple complex rearrangements associated with deletions in the 6q23-27 region in Sézary syndrome.

The 6q23-27 region, recurrently deleted in Sézary syndrome (SS), was characterized at the molecular level in 13 SS patients and SS cell line SeAx. Using fine-tiling comparative genomic hybridization, deletions within the 6q23-27 region were detected in half of the samples (six patients and SeAx). All samples with deletions were further analyzed by ligation-mediated PCR. In addition, in one patient sample and in SeAx, paired-end next-generation sequencing was performed on the HiSeq2000 Illumina platform. Using those techniques, 23 rearrangements associated with the deletions were identified. The majority of rearrangements showed enormous complexity and diversity, including eight inversions, three transpositions, and four translocations (with chromosomes 3, 17, 10, and 12). Fifteen genes were disrupted by those rearrangements, the MYB proto-oncogene three times and the interleukin-22 receptor subunit alpha-2 gene (IL22RA2) twice. All three patients with MYB alterations showed low MYB expression, whereas seven of the remaining patients showed overexpression. Most patients overexpressing MYB also presented increased expression of MYC, HSPA8, and BCL2. Five gene fusions were identified, of which two, CCDC28A-IL22RA2 and AIG1-GOSR1, both in SeAx, were in the same orientation and were expressed at the messenger RNA level.

[Potential pathogens in multiple sclerosis (MS)]. / Potencjalne czynniki patogenne w stwardnieniu rozsianym (SM).

 Multiple sclerosis is a neuroimmunological disease in which etiologic agents have not been identified yet. The etiology of MS is complex in its nature and may involve many different agents acting simultaneously or in a cascade manner leading to the development of the disease. The causes of MS development were sought among the factors associated with HLA and TCR genes and human endogenous retroviruses (HERV). Environmental factors such as bacterial, fungal and viral infections as well as potential participation of vitamin D in the pathogenesis of the disease have also been examined. The current state of knowledge concerning potential factors participating in the etiopathogenesis of multiple sclerosis has been reviewed in this paper.

Presence of hepatitis C virus (HCV)-RNA in peripheral blood mononuclear cells in HCV serum negative patients during interferon and ribavirin therapy.

Identification of hepatitis C virus (HCV)-RNA in blood serum is crucial for hepatitis C diagnosis and for appropriate treatment. Detection of HCV-RNA in blood serum is used for therapy monitoring of patients with hepatitis C. Despite HCV-RNA elimination from blood serum during treatment in some patients, HCV viremia appears again after the completion of therapy. The aim of this study was to assess HCV-RNA in peripheral blood mononuclear cells (PBMCs) of hepatitis C patients in relation to HCV-RNA and antibodies to HCV in the serum. The study involved 71 patients undergoing anti-viral therapy (interferon and ribavirin). RNA isolated from serum and PBMCs was examined for the presence of HCV-RNA by an RT-PCR technique using specific oligonucleotide primers or by commercially available kits. In order to show the possible presence of HCV sequences in PBMCs, molecular DNA probes were constructed with a PCR amplicon and biotin-labelled by nick translation, and FISH and extended chromatin fibers in situ hybridization (ECFs-FISH) techniques were used. A 24-month follow-up study revealed that 34 out of 59 patients (58%) eliminated HCV-RNA from their sera. In the serum negative group, HCV-RNA was detected in PBMCs of 2 patients. The presence of HCV-RNA in PBMCs was confirmed by the FISH technique. In the ECFs-FISH procedure, no signal was found in all examined patients. Our data suggest that PBMCs infected with HCV can serve as a virus reservoir. HCV-RNA serum negative patients who have HCV-RNA in their leukocytes after completion of anti-viral therapy would be at great risk of hepatitis C recurrence. These HCV-RNA serum negative but PBMCs positive patients would be a potential source of HCV spread.

Amplification of hTERT and hTERC genes in leukemic cells with high expression and activity of telomerase.

Reactivation of telomerase plays an important role in carcinogenesis. Malignant cells almost always possess high activity and expression of telomerase. The aim of this study was to see whether there is any relationship between telomerase activity and expression and hTERT and hTERC gene amplification in acute lymphoblastic leukemia (ALL) and non-lymphoblastic leukemia (ANLL) cells. In addition telomere length was tested in leukemic cells at the time of diagnosis and during remission. Expression of the three components of telomerase (hTERT, hTERC and TP1) as well as telomerase activity was found both in ALL and ANLL cells. Telomerase activity was diminished in patients in remission. The leukemic cells showed considerable heterogeneity of terminal restriction fragments, that is telomere length. ALL cells showed a variable pattern of telomere length in contrast to ANLL cells which produced a predominantly short telomere pattern. Telomere length in the lymphocytes of leukemia patients was shorter in remission as compared to the time of diagnosis. FISH analysis revealed amplification of hTERT and hTERC genes in ALL and ANLL cells. Quantitative analysis showed that leukemic cells possess higher number of hTERT and hTERC copies than the normal PBL. Our results suggest that the activation of telomerase in leukemic cells is connected with amplification of hTERT and hTERC genes. The high expression and activity of telomerase found in leukemic cells may be partially explained by amplified hTERT and hTERC genes. Amplification of the telomerase genes seems to be a common event in carcinogenesis and may play a role in telomerase reactivation leading to cell immortalization.

Multiple sclerosis-associated virus-related pol sequences found both in multiple sclerosis and healthy donors are more frequently expressed in multiple sclerosis patients.

In the etiopathogenesis of multiple sclerosis (MS), both genetic and environmental factors play an important role. Among environmental factors, viral infections are most likely connected with the etiology of MS. There are many evidence suggesting possible involvement of retroviruses in the development of autoimmune diseases including MS. Multiple sclerosis-associated retrovirus (MSRV) seems to be the important candidate for viral etiology of MS. The aim of the study was to analyze MSRV pol sequences in patients with MS. As control, groups of myasthenia gravis, Parkinson's disease, and migraine patients, and healthy individuals have been studied. The MSRV pol sequences have been analyzed in RNA isolated from the serum and in DNA and RNA of peripheral blood lymphocytes from untreated MS patients and control groups. The MSRV pol sequences have been detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and PCR technique, using specific oligonucleotide primers. In the serum RNA (cDNA), MSRV pol sequences have been identified in 31/32 MS patients. MSRV pol sequences were detected in serum cDNA of 9/17 myasthenia gravis patients, 7/16 Parkinson's disease patients, 10/21 migraine patients, and 13/27 healthy individuals. MSRV pol sequences were observed also in RNA from lymphocytes of all MS patients, 12/17 myasthenia gravis patients, 9/16 Parkinson's disease patients, 14/21 migraine patients, and 18/27 healthy donors. In the DNA from peripheral blood lymphocytes of all studied patients and healthy individuals, MSRV pol sequences have been found. The observed pattern of fiber-fluorescence in situ hybridization (FISH) signals suggests the presence of multiple copies of MSRV pol sequences, most likely tandemly dispersed in the genome. It can be concluded that MSRV pol sequences are endogenous, widespread in lymphocytes DNA, and transcribed into RNA of MS patients as well as of other studied patients and healthy individuals. However, more frequent expression of MSRV sequences detected in lymphocytes RNA (cDNA), as well as their presence in higher frequency in the serum of MS patients, may suggest the involvement of MSRV in the etiopathogenesis on MS.

MSRV pol sequence copy number as a potential marker of multiple sclerosis.

Multiple sclerosis (MS) is a neurological disease in which demyelination in the brain and spinal cord is observed. The causal influence of bacterial/viral infections and genetic/immune factors in the etiology of multiple sclerosis is suggested. Multiple sclerosis-related retrovirus (MSRV) is one of the potential agents, which can lead to development of the disease. The aim of cytogenetic studies was assessment of MSRV pol sequence copy number in patients with MS compared to normal individuals. Cytogenetic slides with interphase nuclei and extended chromatin fibers were prepared from peripheral blood of 16 patients with MS and 10 healthy individuals. Fluorescence in situ hybridization (FISH) with biotinylated product of polymerase chain reaction was used in order to analyze MSRV pol sequence copy number in the examined material. Detection of MSRV pol probe was carried out by immunological reaction with avidin-fluorescein and biotinylated anti-avidin. MSRV pol sequence copy number was significantly greater in MS patients than in normal individuals. Using FISH technique to extended chromatin fibers, it was observed that MSRV pol exists as tandem repeats on various chromosomes. The increased number of MSRV pol sequence has been found on chromatin fibers of MS patients as compared to healthy controls.