Chromatin structure governs a number of cellular processes including DNA replication, transcription, and DNA repair. During DNA replication, chromatin structure including the basic repeating unit of chromatin, the nucleosome, is temporarily disrupted, and then reformed immediately after the passage of the replication fork. This coordinated process of nucleosome assembly during DNA replication is termed replication-coupled nucleosome assembly. Disruption of this process can lead to genome instability, a hallmark of cancer cells. Therefore, addressing how replication-coupled nucleosome assembly is regulated has been of great interest. Here, we review the current status of this growing field of interest, highlighting recent advances in understanding the regulation of this important process by the dynamic interplay of histone chaperones and histone modifications.
Acetylation ; Animals ; DNA Replication ; Histone Chaperones ; metabolism ; Histones ; metabolism ; Humans ; Nucleic Acid Conformation ; Nucleosomes ; metabolism ; Protein Processing, Post-Translational

OBJECTIVETo investigate the expression level of SET gene in patients with acute myeloid leukemia (AML) and evaluate its significance.

METHODSThe expression level of SET gene in 141 de novo AML patients was determined by real time quantitative PCR (RQ-PCR), and its relationship with the clinical features and outcomes of these patients were analyzed.

RESULTSSET gene transcript level was detected in 141 AML patients with the median expression level of 0.86(range 0.02-15.69). AML patients with higher SET gene expression had a higher level of white blood cell (WBC ≥ 100 × 10⁹/L) count than of lower SET gene expression ones (31.0% vs 11.4%, P=0.005). In the 136 patients who received treatment after diagnosis, higher SET gene expression group had lower complete remission rate (50.0%) than of lower expression cohort (73.5%) after two cycles of chemotherapy (P=0.005). Survival analysis showed that patients with higher SET gene expression had significantly shorter overall survival(OS) (10 months vs 22 months, P=0.001) and event-free survival (EFS) (2 months vs 14 months, P=0.005) than of lower SET gene expression ones. Multivariate COX regression analysis showed SET overexpression was an independent prognostic factor for OS. In the patients with the normal karyotype, higher SET expression group also had significantly shorter OS (12 months vs 35 months, P=0.010) and EFS (4 months vs 14 months, P=0.026) than of lower SET expression ones.

CONCLUSIONHigh expression of SET gene was associated with poor prognosis and might be a prognostic molecular marker of AML.

Disease-Free Survival ; Gene Expression Regulation, Neoplastic ; Histone Chaperones ; genetics ; Humans ; Leukemia, Myeloid, Acute ; genetics ; Prognosis ; Remission Induction ; Transcription Factors ; genetics

Gene Expression Regulation, Fungal ; Gene Silencing ; Heterochromatin ; metabolism ; Histone Chaperones ; genetics ; metabolism ; Saccharomyces cerevisiae ; genetics ; metabolism ; Saccharomyces cerevisiae Proteins ; genetics ; metabolism ; Transcriptional Elongation Factors ; genetics ; metabolism

HSP90 is a molecular chaperone that increases the stability of client proteins. Cancer cells show higher HSP90 expression than normal cells because many client proteins play an important role in the growth and survival of cancer cells. HSP90 inhibitors mainly bind to the ATP binding site of HSP90 and inhibit HSP90 activity, and these inhibitors can be distinguished as ansamycin and non-ansamycin depending on the structure. In addition, the histone deacetylase inhibitors inhibit the activity of HSP90 through acetylation of HSP90. These HSP90 inhibitors have undergone or are undergoing clinical trials for the treatment of cancer. On the other hand, recent studies have reported that various reagents induce cleavage of HSP90, resulting in reduced HSP90 client proteins and growth suppression in cancer cells. Cleavage of HSP90 can be divided into enzymatic cleavage and non-enzymatic cleavage. Therefore, reagents inducing cleavage of HSP90 can be classified as another class of HSP90 inhibitors. We discuss that the cleavage of HSP90 can be another mechanism in the cancer treatment by HSP90 inhibition.
Acetylation ; Adenosine Triphosphate ; Binding Sites ; Drug Therapy ; Hand ; Heat-Shock Proteins ; Histone Deacetylase Inhibitors ; Hot Temperature ; Indicators and Reagents ; Molecular Chaperones ; Rifabutin

Calmegin is a testis-specific molecular chaperon playing a key role in spermatogenesis. However, the transcriptional regulatory mechanisms for calmegin expression are entirely unknown. Herein, we revealed that calmegin is transcriptionally regulated by histone deacetylase (HDAC) and CpG methyltransferase. The cDNA microarray analysis of the human fibrosarcoma cells treated with trichostatin A (TSA) showed an increased level of calmegin mRNA. The induction of calmegin mRNA by TSA was added by the treatment with 5-aza-2'-deoxycytidine (5'Aza- dC), implying that epigenetic alterations are involved in the transcriptional repression of the gene. Moreover, chromatin immunoprecipitation assay using an anti-acetyl-histone H3 antibody exhibited that the proximal region (-152~-31) of the calmegin promoter is responsible for HDAC-mediated transcriptional repression of the gene. These results demonstrate that calmegin expression is regulated by HDAC and CpG methyltransferase in a coordinative way.
Animals ; Calcium-Binding Proteins/*genetics ; Cell Line, Tumor ; *Gene Expression Regulation ; Histone Deacetylases/*metabolism ; Humans ; Male ; Methyltransferases/*metabolism ; Mice ; Molecular Chaperones/*genetics ; Organ Specificity ; Promoter Regions (Genetics)/genetics ; Research Support, Non-U.S. Gov't ; Testis/*metabolism ; *Transcription, Genetic

BACKGROUNDA study of prenatal genetic diagnosis for 22q11.2 microdeletion, which has a wide phenotypic spectrum that involves almost all organs, is rarely reported in China. This study aimed to explore the prevalence of 22q11.2 microdeletion in congenitally malformed fetuses via the fluorescent in situ hybridization (FISH) technique and to investigate the feasibility of use of amniocytes to diagnose 22q11.2 microdeletion syndrome prenatally.

METHODSThe study enrolled 23 cases of fetal cardiac malformation, as indicated by ultrasound in Beijing Anzhen Hospital and 14 cases of non-cardiac malformation, as determined by type-B ultrasound in Beijing Anzhen Hospital and other hospitals. Amniotic fluid was obtained by amniocentesis before odinopoeia, and the stillborn fetuses of the induced labor were preceded to autopsy. The amniotic fluid of 20 cesarean deliveries during the same period of time was used as a control. The TUPLE1 gene in the amniotic fluid of malformed and normal fetuses was assessed by the FISH method.

RESULTSThe prevalence rates of the TUPLE1 gene deletion in the amniotic fluid cells from fetuses with cardiac deformations and fetuses without such malformations were 43.5% and 57.1%, respectively. The deletion of TUPLE1 was significantly associated with fetal malformation.

CONCLUSIONChromosome 22q11.2 microdeletion is one of the major factors leading to fetal congenital malformations, and prenatal FISH screening for 22q11.2 microdeletion syndrome is technically feasible using amniocytes.

Adult ; Amniocentesis ; Cell Cycle Proteins ; genetics ; Chromosome Deletion ; Chromosomes, Human, Pair 22 ; genetics ; Feasibility Studies ; Female ; Fetal Diseases ; genetics ; Gestational Age ; Histone Chaperones ; genetics ; Humans ; In Situ Hybridization, Fluorescence ; Pregnancy ; Pregnancy Outcome ; Prenatal Diagnosis ; Transcription Factors ; genetics

Cell Line ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Histone Chaperones ; metabolism ; Humans ; Liver ; cytology ; Protein Interaction Maps ; Solvents ; administration & dosage ; toxicity ; Transcription Factors ; metabolism ; Trichloroethylene ; administration & dosage ; toxicity

OBJECTIVETo explore the effect of RNA interference of human I2PP2A gene on the proliferation and apoptosis of retinoic acid-resistant human acute promyelocytic leukemia (APL) cell line NB4-R1.

METHODSDesigned and constructed a RNA interference lentiviral vector I2PP2A-shRNA which targeted against I2PP2A gene, then transfected it into NB4-R1 via polybrene mediation. The I2PP2A expression levels before and after transfection were detected by qRT-PCR and Western blot, respectively. Meanwhile, the proliferation and apoptosis rates of each group were determined by CCK-8 and flow cytometry assay. The protein expressions of caspase-8 and PARP were detected by Western blot.

RESULTSBoth qRT-PCR and Western blot data showed the I2PP2A expression level was significantly downregulated in the transfection group. The I2PP2A mRNA expression level decreased by (70.0 ± 9.6)% and (64.0 ± 6.2)% respectively, compared with blank control and negative control group, and the I2PP2A protein expression level showed a consistent trend. CCK-8 proliferation assay indicated the NB4-R1 cell proliferation rate in I2PP2A-shRNA transfection group significantly reduced compared to blank control group (P<0.05). Flow cytometry results showed that NB4-R1 apoptosis rate in I2PP2A-shRNA transfection group increased by (6.30 ± 0.67) times and (6.04 ± 0.56) times, respectively (P<0.01). After inhibition of I2PP2A, the total caspase-8 and total PARP expressions decreased by (44.0 ± 3.1)% and (57.0 ± 4.0)%, respectively; Meanwhile, the cleaved caspase-8 (p43) and cleaved PARP (p89) increased by (36.0 ± 2.5)% and (45.0 ± 4.8)%, respectively compared with blank control group (P<0.05).

CONCLUSIONI2PP2A gene silenced by RNA interference could inhibit the proliferation and promote the apoptosis of NB4-R1, which may be regulated through caspase-8-induced exogenous apoptosis pathway.

Apoptosis ; genetics ; Caspase 8 ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; genetics ; Drug Resistance, Neoplasm ; Histone Chaperones ; genetics ; metabolism ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; RNA Interference ; Transcription Factors ; genetics ; metabolism ; Tretinoin ; pharmacology

OBJECTIVETo investigate the effect of silencing SET gene on the biological characteristics of acute promyelocytic leukemia NB4-R1 cells.

METHODSThe expression vector of pGCSIL containing SET-shRNA were transfected into 293T cells by using other packaging plasmids. The supernatant of the 293T cells was harvested for lentivirus. The SET-shRNA lentiviral vector was transfected into acute promyelocytic leukemia NB4-R1 cells and a stably transfected cell line was established. Real-time quantitative PCR and Western blot were used to assay the silencing efficiency on SET gene and the expression of PP2A. The cell cycle distribution was tested by flow cytometry.

RESULTSThe expression of SET in experimental group statistically decreased as compared with that of the control group. The expression of PP2A was obviously raised at the level of mRNA and protein. The percentage of NB4-R1 cells in G0/G1 phase significantly increased, while the percentage of cells in S phase significantly decreased.

CONCLUSIONThe silencing gene in acute promyelocytic leukemia NB4-R1 cells using SET-shRNA lentiviral vector can increase the expression of PP2A and interfere of the cell cycle in NB4-R1 cells. This study has laid a experimental base for targed therapy of patients with acute promyelocytic leukemia.

Cell Cycle ; Cell Line, Tumor ; Gene Silencing ; Genetic Vectors ; HEK293 Cells ; Histone Chaperones ; genetics ; Humans ; Lentivirus ; Leukemia, Promyelocytic, Acute ; genetics ; pathology ; Protein Phosphatase 2 ; metabolism ; RNA, Messenger ; RNA, Small Interfering ; Transcription Factors ; genetics ; Transfection

The purpose of this study was to analyze the gene rearrangement pattern of immunoglobulin and T-cell receptor (Ig/TR) and its clinical characteristics in three children with SET-NUP214 fusion gene positive leukemia/lymphoma. The transcript of SET-NUP214 fusion gene was detected by RT-nested PCR. The pattern of Ig/TR gene rearrangement was analyzed by using the BIOMED-2 multiplex PCR assays. Allelic-specific primers were designed for further monitoring the minimal residual disease (MRD). The results indicated that the fusion site located between exon 7 of SET and exon 18 of NUP214 at mRNA level in the three patients. The diagnoses were made as the mixed phenotype of acute leukemia (MPAL) for patients 1, acute T-lymphoblastic leukemia (T-ALL) for patients 2, and stage IV T-lymphoblastic lymphoma (T-LBL) for patients 3, respectively. Patient 1 responded to chemotherapy very poorly and relapsed at month 6 after hematopoietic stem cell transplantation. Patient 2 had high MRD (> 10(-2)) at the end of inducing remission therapy (day 33) which implied poor outcome, and died of toxic epidermal necrolysis and sequent serious infection. Patient 3 achieved hematological complete remission (CR) and MRD negative at day 15 and day 33 respectively. The duration of CR lasted for 30 months. Clonal TR gene rearrangements were detected in all the three patients. The rearrangements of TRD, TRG and TRB were found in patient 1 and 3. The rearrangements of TRD, TRB, IgH and IgK Kde were detected in patient 2. All the 6 TRB rearrangements detected were incomplete rearrangements, whereas 85.7% and 14.3% of the TRD, and TRG rearrangements were complete and incomplete, respectively. It is concluded that the transformation of SET-NUP214(+) leukemia/lymphoma cells may occur after the rearrangements of TRD and TRG and shortly after TRB rearrangement. The leukemia/lymphoma cells of patient 1 and 2 are more immature which may be related with poor outcome or response to chemotherapy.
Child ; Female ; Gene Fusion ; Gene Rearrangement, T-Lymphocyte ; Histone Chaperones ; genetics ; Humans ; Immunoglobulins ; genetics ; Male ; Neoplasm, Residual ; diagnosis ; genetics ; Nuclear Pore Complex Proteins ; genetics ; Oncogene Proteins, Fusion ; genetics ; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; Transcription Factors ; genetics