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Crystal structure of the double homeodomain of DUX4 in complex with DNA
Structural highlights
DiseaseDUX4_HUMAN Facioscapulohumeral dystrophy. The gene represented in this entry is involved in disease pathogenesis. The disease is caused by deletion of an integral number of units of a 3.3-kb tandem repeats, termed D4Z4 macrosatellite, located on chromosome 4q35. In unaffected subjects, the D4Z4 array consists of 11-150 repeats, while in FSHD1 patients, the array is reduced to 1-10 repeats (PubMed:19320656). DUX4 is located in D4Z4 macrosatellite which is epigenetically repressed in somatic tissues. D4Z4 chromatin relaxation in FSHD1 results in inefficient epigenetic repression of DUX4 and a variegated pattern of DUX4 protein expression in a subset of skeletal muscle nuclei. Ectopic expression of DUX4 in skeletal muscle activates the expression of stem cell and germline genes, and, when overexpressed in somatic cells, DUX4 can ultimately lead to cell death.[1] FunctionDUX4_HUMAN Involved in transcriptional regulation. May regulate microRNA (miRNA) expression.[2] [3] Publication Abstract from PubMedDouble homeobox (DUX) transcription factors are unique to eutherian mammals. DUX4 regulates expression of repetitive elements during early embryogenesis, but misexpression of DUX4 causes facioscapulohumeral muscular dystrophy (FSHD) and translocations overexpressing the DUX4 double homeodomain cause B cell leukemia. Here, we report the crystal structure of the tandem homeodomains of DUX4 bound to DNA. The homeodomains bind DNA in a head-to-head fashion, with the linker making anchoring DNA minor-groove interactions and unique protein contacts. Remarkably, despite being tandem duplicates, the DUX4 homeodomains recognize different core sequences. This results from an arginine-to-glutamate mutation, unique to primates, causing alternative positioning of a key arginine side chain in the recognition helix. Mutational studies demonstrate that this primate-specific change is responsible for the divergence in sequence recognition that likely drove coevolution of embryonically regulated repeats in primates. Our work provides a framework for understanding the endogenous function of DUX4 and its role in FSHD and cancer. Crystal Structure of the Double Homeodomain of DUX4 in Complex with DNA.,Lee JK, Bosnakovski D, Toso EA, Dinh T, Banerjee S, Bohl TE, Shi K, Orellana K, Kyba M, Aihara H Cell Rep. 2018 Dec 11;25(11):2955-2962.e3. doi: 10.1016/j.celrep.2018.11.060. PMID:30540931[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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