82-kDa choline acetyltransferase and SATB1 localize to ß-amyloid induced matrix attachment regions.

The M-transcript of human choline acetyltransferase (ChAT) produces an 82-kDa protein (82-kDa ChAT) that concentrates in nuclei of cholinergic neurons. We assessed the effects of acute exposure to oligomeric amyloid-ß1-42 (Aß1-42) on 82-kDa ChAT disposition in SH-SY5Y neural cells, finding that acute exposure to Aß1-42 results in increased association of 82-kDa ChAT with chromatin and formation of 82-kDa ChAT aggregates in nuclei. When measured by chromatin immunoprecipitation with next-generation sequencing (ChIP-seq), we identified that Aß1-42-exposure increases 82-kDa ChAT association with gene promoters and introns. The Aß1-42-induced 82-kDa ChAT aggregates co-localize with special AT-rich binding protein 1 (SATB1), which anchors DNA to scaffolding/matrix attachment regions (S/MARs). SATB1 had a similar genomic association as 82-kDa ChAT, with both proteins associating with synapse and cell stress genes. After Aß1-42 -exposure, both SATB1 and 82-kDa ChAT are enriched at the same S/MAR on the APP gene, with 82-kDa ChAT expression attenuating an increase in an isoform-specific APP mRNA transcript. Finally, 82-kDa ChAT and SATB1 have patterned genomic association at regions enriched with S/MAR binding motifs. These results demonstrate that 82-kDa ChAT and SATB1 play critical roles in the response of neural cells to acute Aß-exposure.

Addition of a Synthetically Fabricated Osteoinductive Biphasic Calcium Phosphate Bone Graft to BMP2 Improves New Bone Formation.

BACKGROUND: Bone morphogenetic protein-2 (BMP2) has been successfully utilized in dentistry to promote new bone formation because of its osteoinductive ability to recruit mesenchymal progenitor cells and induce their differentiation to bone-forming osteoblasts. Recently, novel biphasic calcium phosphate scaffolds have been developed with similar osteoinductive properties capable of forming ectopic bone formation. PURPOSE: The aim of the present study was to assess whether the combination of BMP2 with this novel Biphasic Calcium Phosphate (BCP) scaffold may additionally promote new bone regeneration. MATERIALS AND METHODS: Cylindrical bone defects measuring 2.5 mm were created bilaterally in the femurs of 18 Wistar rats. After 4 weeks, the following six groups were assessed for new bone formation by micro-computed tomography (CT) as well as histological assessment: 1) collagen scaffolds + 20 µg of BMP2; 2) collagen scaffolds + 50 µg of BMP2; 3) collagen scaffolds + 100 µg of BMP2; 4) BCP scaffolds + 20 µg of BMP2; 5) BCP scaffolds + 50 µg of BMP2; and 6) BCP scaffolds + 100 µg of BMP2. Furthermore, tartrate-resistant acid phosphatase (TRAP) staining was utilized to assess osteoclast activity and osteoclast number. The release kinetics of BMP2 from both BCP and collagen scaffolds was investigated over a 14-day period. RESULTS: The results from present study demonstrate that BMP2 is able to promote new bone formation in a concentration dependant manner when loaded with either a collagen scaffolds or BCP scaffolds. Micro-CT analysis demonstrated significantly higher levels of new bone formation in groups containing BCP + BMP2 when compared with collagen scaffolds + BMP2. BMP2 had little effect on osteoclast activity; however, less TRAP staining and osteoclast number was observed in the defects receiving collagen scaffolds when compared with BCP scaffolds. The release of BMP2 over time was rapidly released after 1 day on BCP scaffolds whereas a gradually release over time was observed for collagen scaffolds up to 14 days. CONCLUSION: The osteoinductive properties of BMP2 may further be enhanced by its combination with a novel synthetically fabricated osteoinductive BCP scaffold. Future clinical testing is required to further assess these preliminary findings.

CTCF binds to sites in the major histocompatibility complex that are rapidly reconfigured in response to interferon-gamma.

Activation of the major histocompatibility complex (MHC) by interferon-gamma (IFN-γ) is a fundamental step in the adaptive immune response to pathogens. Here, we show that reorganization of chromatin loop domains in the MHC is evident within the first 30 min of IFN-γ treatment of fibroblasts, and that further dynamic alterations occur up to 6 h. These very rapid changes occur at genomic sites which are occupied by CTCF and are close to IFN-γ-inducible MHC genes. Early responses to IFN-γ are thus initiated independently of CIITA, the master regulator of MHC class II genes and prepare the MHC for subsequent induction of transcription.

Reconfiguration of genomic anchors upon transcriptional activation of the human major histocompatibility complex.

The folding of chromatin into topologically constrained loop domains is essential for genomic function. We have identified genomic anchors that define the organization of chromatin loop domains across the human major histocompatibility complex (MHC). This locus contains critical genes for immunity and is associated with more diseases than any other region of the genome. Classical MHC genes are expressed in a cell type-specific pattern and can be induced by cytokines such as interferon-gamma (IFNG). Transcriptional activation of the MHC was associated with a reconfiguration of chromatin architecture resulting from the formation of additional genomic anchors. These findings suggest that the dynamic arrangement of genomic anchors and loops plays a role in transcriptional regulation.

Scaffold/matrix attachment regions (S/MARs): relevance for disease and therapy.

There is increasing awareness that processes, such as development, aging and cancer, are governed, to a considerable extent, by epigenetic processes, such as DNA and histone modifications. The sites of these modifications in turn reflect their position and role in the nuclear architecture. Since epigenetic changes are easier to reverse than mutations, drugs that remove or add the chemical tags are at the forefront of research for the treatment of cancerous and inflammatory diseases. This review will use selected examples to develop a unified view that might assist the systematic development of novel therapeutic regimens.

Selective matrix attachment regions in T helper cell subsets support loop conformation in the Ifng gene.

Cytokine genes undergo progressive changes in chromatin organization when naïve CD4+ T helper (Th) cells differentiate into committed Th1 and Th2 lineages. Here, we analyzed nuclear matrix attachment regions (MARs) in the Ifng gene by DNA array technique in unactivated and activated CD4+ Th cells. This approach was combined with analysis of spatial organization of the Ifng gene by chromosome conformation capture approach to assess the relationship between the gene conformation and matrix attachment organization in functionally different cell subsets. We report that the Ifng gene in unactivated cells displays a linear conformation, but in T-cell receptor-activated cells, it adopts a loop conformation. The selective MARs support the spatial gene organization and characteristically define the Ifng gene in functionally different cell subsets. The pattern of interaction of the Ifng gene with the nuclear matrix dynamically changes in a lineage-specific manner in parallel with the changes in Ifng gene conformation. The data suggest that such structural dynamics provide the means for transcriptional regulation of the Ifng gene in the course of activation and differentiation of CD4+Th cells.