DUX4

This gene is located within a D4Z4 repeat array in the subtelomeric region of chromosome 4q. The D4Z4 repeat is polymorphic in length; a similar D4Z4 repeat array has been identified on chromosome 10. Each D4Z4 repeat unit has an open reading frame (named DUX4) that encodes two homeoboxes; the repeat-array and ORF is conserved in other mammals. The encoded protein has been reported to function as a transcriptional activator of paired-like homeodomain transcription factor 1 (PITX1; GeneID 5307). Contraction of the macrosatellite repeat causes autosomal dominant facioscapulohumeral muscular dystrophy (FSHD). Alternative splicing results in multiple transcript variants. [provided by RefSeq, Apr 2015]

Double Homeobox 4

Isoform 1:
Transcription factor that is selectively and transiently expressed in cleavage-stage embryos (PubMed:28459457).

Binds to double-stranded DNA elements with the consensus sequence 5'-TAATCTAATCA-3' (PubMed:28459457, PubMed:28459454, PubMed:29572508, PubMed:30540931, PubMed:30315230).

Binds to chromatin containing histone H3 acetylated at 'Lys-27' (H3K27ac) and promotes deacetylation of H3K27ac. In parallel, binds to chromatin that lacks histone H3 acetylation at 'Lys-27' (H3K27ac) and recruits EP300 and CREBBP to promote acetylation of histone H3 at 'Lys-27' at new sites (PubMed:26951377).

Involved in transcriptional regulation of numerous genes, primarily as transcriptional activator, but mediates also repression of a set of target genes (PubMed:17984056, PubMed:27378237, PubMed:26951377, PubMed:28459457, PubMed:28459454, PubMed:29618456, PubMed:30540931, PubMed:29572508).

Promotes expression of ZSCAN4 and KDM4E, two proteins with essential roles during early embryogenesis (PubMed:27378237, PubMed:26951377, PubMed:28459457, PubMed:29618456).

Heterologous expression in cultured embryonic stem cells mediates also transcription of HERVL retrotransposons and transcripts derived from ACRO1 and HSATII satellite repeats (PubMed:28459457).

May activate expression of PITX1 (PubMed:17984056).

May regulate microRNA (miRNA) expression (PubMed:24145033).

Inappropriate expression can inhibit myogenesis and promote apoptosis (PubMed:26951377, PubMed:28935672, PubMed:29618456).

Isoform 2:
Probably inactive as a transcriptional activator, due to the absence of the C-terminal region that is important for transcriptional activation. Can inhibit transcriptional activation mediated by isoform 1. Heterologous expression of isoform 2 has no deleterious effect on cell survival.

Apoptotic process Source: UniProtKB
Negative regulation of cell population proliferation Source: UniProtKB
Negative regulation of G0 to G1 transition Source: UniProtKB
Positive regulation of transcription by RNA polymerase II Source: UniProtKB
Regulation of transcription by RNA polymerase II Source: GO_Central

Isoform 1: Nucleus. Actively transported through the nuclear pore complex (NPC).
Isoform 2: Nucleus

Facioscapulohumeral muscular dystrophy 1 (FSHD1):
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.
A degenerative muscle disease characterized by slowly progressive weakness of the muscles of the face, upper-arm, and shoulder girdle. The onset of symptoms usually occurs in the first or second decade of life. Affected individuals usually present with impairment of upper extremity elevation. This tends to be followed by facial weakness, primarily involving the orbicularis oris and orbicularis oculi muscles.