Discovery of BAZ1A bromodomain inhibitors with the aid of virtual screening and activity evaluation.

BAZ1A is a bromodomain-containing protein, and has been recognized as a potential target for multiple diseases, particularly cancer. However, there is no BAZ1A inhibitor reported so far. In this study, we used a consensus docking/scoring strategy to screen for BAZ1A bromodomain inhibitors from commercial chemical libraries and an in-house chemical database. The retrieved hit compounds were evaluated experimentally and four compounds were found to be active against BAZ1A bromodomain. To the most active compounds, similarity and substructure searches were used to find more BAZ1A bromodomain inhibitors. Among all the obtained active compounds, Cpd-2 is the most potent one, which showed a KD value of 0.52 µM. The interaction model of Cpd-2 with BAZ1A bromodomain was revealed by molecular docking. In a cellular assay, Cpd-2 displayed good anti-viability activity against cancer cell lines expressing a high level of BAZ1A. Overall, we discovered a number of BAZ1A bromodomain inhibitors for the first time, which can be a good starting point for subsequent drug discovery targeting BAZ1A bromodomain.

A Role for the Chromatin-Remodeling Factor BAZ1A in Neurodevelopment.

Chromatin-remodeling factors are required for a wide range of cellular and biological processes including development and cognition, mainly by regulating gene expression. As these functions would predict, deregulation of chromatin-remodeling factors causes various disease syndromes, including neurodevelopmental disorders. Recent reports have linked mutations in several genes coding for chromatin-remodeling factors to intellectual disability (ID). Here, we used exome sequencing and identified a nonsynonymous de novo mutation in BAZ1A (NM_182648.2:c.4043T > G, p.Phe1348Cys), encoding the ATP-utilizing chromatin assembly and remodeling factor 1 (ACF1), in a patient with unexplained ID. ACF1 has been previously reported to bind to the promoter of the vitamin D receptor (VDR)-regulated genes and suppress their expression. Our results show that the patient displays decreased binding of ACF1 to the promoter of the VDR-regulated gene CYP24A1. Using RNA sequencing, we find that the mutation affects the expression of genes involved in several pathways including vitamin D metabolism, Wnt signaling and synaptic formation. RNA sequencing of BAZ1A knockdown cells and Baz1a knockout mice revealed that BAZ1A carry out distinctive functions in different tissues. We also demonstrate that BAZ1A depletion influence the expression of genes important for nervous system development and function. Our data point to an important role for BAZ1A in neurodevelopment, and highlight a possible link for BAZ1A to ID.

Chromatin-remodeling factor BAZ1A/ACF1 targets UV damage sites in an MLL1-dependent manner to facilitate nucleotide excision repair.

Ultraviolet (UV) light irradiation generates pyrimidine dimers on DNA, such as cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts. Such dimers distort the high-order DNA structure and prevent transcription and replication. The nucleotide excision repair (NER) system contributes to resolving this type of DNA lesion. There are two pathways that recognize pyrimidine dimers. One acts on transcribed strands of DNA (transcription-coupled NER), and the other acts on the whole genome (global genome-NER; GG-NER). In the latter case, DNA damage-binding protein 2 (DDB2) senses pyrimidine dimers with several histone modification enzymes. We previously reported that histone acetyltransferase binding to ORC1 (HBO1) interacts with DDB2 and facilitates recruitment of the imitation switch chromatin remodeler at UV-irradiated sites via an unknown methyltransferase. Here, we found that the phosphorylated histone methyltransferase mixed lineage leukemia 1 (MLL1) was maintained at UV-irradiated sites in an HBO1-dependent manner. Furthermore, MLL1 catalyzed histone H3K4 methylation and recruited the chromatin remodeler bromodomain adjacent to zinc finger domain 1A (BAZ1A)/ATP-utilizing chromatin assembly and remodeling factor 1 (ACF1). Depletion of MLL1 suppressed BAZ1A accumulation at UV-irradiated sites and inhibited the removal of CPDs. These data indicate that the DDB2-HBO1-MLL1 axis is essential for the recruitment of BAZ1A to facilitate GG-NER.

BAZ1B the Protean Protein.

The bromodomain adjacent to the zinc finger domain 1B (BAZ1B) or Williams syndrome transcription factor (WSTF) are just two of the names referring the same protein that is encoded by the WBSCR9 gene and is among the 26-28 genes that are lost from one copy of 7q11.23 in Williams syndrome (WS: OMIM 194050). Patients afflicted by this contiguous gene deletion disorder present with a range of symptoms including cardiovascular complications, developmental defects as well as a characteristic cognitive and behavioral profile. Studies in patients with atypical deletions and mouse models support BAZ1B hemizygosity as a contributing factor to some of the phenotypes. Focused analysis on BAZ1B has revealed this to be a versatile nuclear protein with a central role in chromatin remodeling through two distinct complexes as well as being involved in the replication and repair of DNA, transcriptional processes involving RNA Polymerases I, II, and III as well as possessing kinase activity. Here, we provide a comprehensive review to summarize the many aspects of BAZ1B function including its recent link to cancer.

14q12q13.2 microdeletion syndrome: Clinical characterization of a new patient, review of the literature, and further evidence of a candidate region for CNS anomalies.

BACKGROUND: Chromosome 14q11-q22 deletion syndrome (OMIM 613457) is a rare contiguous gene syndrome. Two regions of overlap (RO) of the 14q12q21.1 deletion have been identified: a proximal region (RO1), including FOXG1(*164874), NKX2-1(*600635), and PAX9(*167416) and a distal region (RO2), including NKX2-1 and PAX9. We report a 6-year-old boy with mild dysmorphic facial features, global developmental delay, and hypoplasia of the corpus callosum. METHODS AND RESULTS: Array-CGH analysis revealed a 14q12q13.2 microdeletion. We compared the phenotype of our patient with previously published cases in order to establish a genotype-phenotype correlation. CONCLUSION: The study hypothesizes the presence of a new RO, not including the previously reported candidate genes, and attempt to define the associated molecular and psychomotor/neurobehavioral phenotype. This region encompasses the distal breakpoint of RO1 and the proximal breakpoint of RO2, and seems to be associated with intellectual disability (ID), hypotonia, epilepsy, and corpus callosum abnormalities. Although more cases are needed, we speculated on SNX6(*606098) and BAZ1A(*605680) as potential candidate genes associated with the corpus callosum abnormalities.

Chromatin remodeling factor BAZ1A regulates cellular senescence in both cancer and normal cells.

AIMS: Cellular senescence is a well-known cancer prevention mechanism, inducing cancer cells to senescence can enhance cancer immunotherapy. However, how cellular senescence is regulated is not fully understood. Dynamic chromatin changes have been discovered during cellular senescence, while the causality remains elusive. BAZ1A, a gene coding the accessory subunit of ATP-dependent chromatin remodeling complex, showed decreased expression in multiple cellular senescence models. We aim to investigate the functional role of BAZ1A in regulating senescence in cancer and normal cells. MATERIALS AND METHODS: Knockdown of BAZ1A was performed via lentivirus mediated short hairpin RNA (shRNA) in various cancer cell lines (A549 and U2OS) and normal cells (HUVEC, NIH3T3 and MEF). A series of senescence-associated phenotypes were quantified by CCK-8 assay, SA-ß-Gal staining and EdU incorporation assay, etc. KEY FINDINGS: Knockdown (KD) of BAZ1A induced series of senescence-associated phenotypes in both cancer and normal cells. BAZ1A-KD caused the upregulated expression of SMAD3, which in turn activated the transcription of p21 coding gene CDKN1A and resulted in senescence-associated phenotypes in human cancer cells (A549 and U2OS). SIGNIFICANCE: Our results revealed chromatin remodeling modulator BAZ1A acting as a novel regulator of cellular senescence in both normal and cancer cells, indicating a new target for potential cancer treatment.

Exome sequencing in syndromic brain malformations identifies novel mutations in ACTB, and SLC9A6, and suggests BAZ1A as a new candidate gene.

BACKGROUND: Syndromic brain malformations comprise a large group of anomalies with a birth prevalence of about 1 in 1,000 live births. Their etiological factors remain largely unknown. To identify causative mutations, we used whole-exome sequencing (WES) in aborted fetuses and children with syndromic brain malformations in which chromosomal microarray analysis was previously unremarkable. METHODS: WES analysis was applied in eight case-parent trios, six aborted fetuses, and two children. RESULTS: WES identified a novel de novo mutation (p.Gly268Arg) in ACTB (Baraitser-Winter syndrome-1), a homozygous stop mutation (p.R2442*) in ASPM (primary microcephaly type 5), and a novel hemizygous X-chromosomal mutation (p.I250V) in SLC9A6 (X-linked syndromic mentaly retardation, Christianson type). Furthermore, WES identified a de novo mutation (p.Arg1093Gln) in BAZ1A. This mutation was previously reported in only one allele in 121.362 alleles tested (dbSNP build 147). BAZ1A has been associated with neurodevelopmental impairment and dysregulation of several pathways including vitamin D metabolism. Here, serum vitamin-D (25-(OH)D) levels were insufficient and gene expression comparison between the child and her parents identified 27 differentially expressed genes. Of note, 10 out of these 27 genes are associated to cytoskeleton, integrin and synaptic related pathways, pinpointing to the relevance of BAZ1A in neural development. In situ hybridization in mouse embryos between E10.5 and E13.5 detected Baz1a expression in the central and peripheral nervous system. CONCLUSION: In syndromic brain malformations, WES is likely to identify causative mutations when chromosomal microarray analysis is unremarkable. Our findings suggest BAZ1A as a possible new candidate gene.

Backbone and side-chain NMR assignments for the bromodomain of mouse BAZ1A (ACF1).

BAZ1A, a non-catalytic subunit of the chromatin remodeler complexes ACF and CHRAC, is thought to modulate the ATPase's activity of the complexes and participate in gene transcription, DNA damage checkpoint and double-strand break repair. Recently, the essential role of BAZ1A in mouse male fertility has also been reported. BAZ1A contains one C-terminal bromodomain, which specifically recognizes acetylation of lysine. Here, we report the backbone and side chain (1)H, (13)C and (15)N resonance assignment of the mouse BAZ1A-bromodomain, as a basis for further functional studies and structure determination.

Mechanism of BAZ1A regulating radiosensitivity of lung cancer cells / 西安交通大学学报(医学版)

Objective: To investigate the effect of siRNA silencing BAZ1A on radiosensitization of human lung adenocarcinoma A549 cells. Methods :A549 cells were randomly divided into transfection reagent control (Ctrl) group, negative control siRNA (siNC) group, and siBAZ1A group. The expression of BAZ1A protein was evaluated by Western blot. The clone formation assay was applied to investigate the survival fraction (SF) of the A549 cells treated with different radiation doses (0, 2, 4, 6, 8, and 10Gy), and one-hit multi-target model was applied to analyze the radiation dose survival curve. MTS assay, scratch assay, and flow cytometry were utilized to determine the relative survival, cell migration abilities, and apoptosis, respectively. Results: The expression level of BAZ1A protein in A549 cells was inhibited by BAZ1A-siRNA transfection. X-ray radiation inhibited the colony formation capacity of A549 cells, and the SF of siBAZ1A group was lower than that of the other two groups with radiation (P<0.05). Compared with those of Ctrl group, the sensitization enhancement ratio (SER) of siNC and siBAZ1A groups was 1.06 and 2.24. Moreover, with the transfection of BAZ1A-siRNA, the relative survival rate and cell migration ability were decreased after X-ray radiation. Besides, the apoptosis rate was higher in siBAZ1A group (P<0.05). Conclusion: Silencing the expression of BAZ1A by siRNA can efficiently improve the sensitization of radiotherapy for A549 cells.