Application Methods: Western Blotting
Background: The CXXC finger protein 1 (CXXC1, CGBP, CFP1) is a key subunit of the human SET1 histone methyltransferase complex (1,2) that methylates histone H3 at Lys4 to create a mark of transcriptionally active promoters (3,4). CXXC1 is enriched at CpG islands where it selectively binds non-methylated CpG motifs to provide a link between global H3K4 methylation and CpG islands (5). Research studies have revealed a role for CXXC1 in the maintenance of cytosine methylation through direct interaction with DNMT1 (6-9). The epigenetic functions of CXXC1 are critical for normal embryonic development. Targeted deletion of the murine Cxxc1 gene results in early embryonic lethality while Cxxc1-null embryonic stem (ES) cells exhibit increased apoptosis and fail to undergo differentiation in vitro following withdrawal of leukemia inhibitory factor LIF (6).
|Human, Monkey, Mouse, Rat|
Application Methods: Immunoprecipitation, Western Blotting
Background: Methylation of DNA at cytosine residues in mammalian cells is a heritable, epigenetic modification that is critical for proper regulation of gene expression, genomic imprinting and development (1,2). Three families of mammalian DNA methyltransferases have been identified: DNMT1, DNMT2 and DNMT3 (1,2). DNMT1 is constitutively expressed in proliferating cells and functions as a maintenance methyltransferase, transferring proper methylation patterns to newly synthesized DNA during replication. DNMT3A and DNMT3B are strongly expressed in embryonic stem cells with reduced expression in adult somatic tissues. DNMT3A and DNMT3B function as de novo methyltransferases that methylate previously unmethylated regions of DNA. DNMT2 is expressed at low levels in adult somatic tissues and its inactivation affects neither de novo nor maintenance DNA methylation. DNMT1, DNMT3A and DNMT3B together form a protein complex that interacts with histone deacetylases (HDAC1, HDAC2, Sin3A), transcriptional repressor proteins (RB, TAZ-1) and heterochromatin proteins (HP1, SUV39H1), to maintain proper levels of DNA methylation and facilitate gene silencing (3-8). Improper DNA methylation contributes to diseased states such as cancer (1,2). Hypermethylation of promoter CpG islands within tumor suppressor genes correlates with gene silencing and the development of cancer. In addition, hypomethylation of bulk genomic DNA correlates with and may contribute to the onset of cancer. DNMT1, DNMT3A and DNMT3B are over-expressed in many cancers, including acute and chronic myelogenous leukemias, in addition to colon, breast and stomach carcinomas (9-12).