Bromo adjacent homology domain containing 1 (BAHD1) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''BAHD1''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
. BAHD1 is involved in
heterochromatin
Heterochromatin is a tightly packed form of DNA or '' condensed DNA'', which comes in multiple varieties. These varieties lie on a continue between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a role ...
formation and transcriptional repression.
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Discovery
''BAHD1'' was first cloned from a human brain cDNA library and the coding sequence was named KIAA0945.
Bierne and colleagues further discovered the function of BAHD1 in the regulation of chromatin structure and gene expression.
Function
BAHD1 acts as a co-repressor by interacting with a set of proteins that promote chromatin compaction and regulate transcription.
Tandem-affinity purification of the BAHD1-associated protein complex in human HEK293 cells identified MIER proteins (
MIER1, MIER2, MIER3), histone deacetylase
HDAC1 and
HDAC2
Histone deacetylase 2 (HDAC2) is an enzyme that in humans is encoded by the ''HDAC2'' gene. It belongs to the histone deacetylase class of enzymes responsible for the removal of acetyl groups from lysine residues at the N-terminal region of the co ...
, histone H3K9 methyltransferase
EHMT2
Euchromatic histone-lysine N-methyltransferase 2 (EHMT2), also known as G9a, is a histone methyltransferase enzyme that in humans is encoded by the ''EHMT2'' gene. G9a catalyzes the mono- and di-methylated states of histone H3 at lysine residue 9 ...
,
heterochromatin protein 1
The family of heterochromatin protein 1 (HP1) ("Chromobox Homolog", CBX) consists of highly conserved proteins, which have important functions in the cell nucleus. These functions include gene repression by heterochromatin formation, transcri ...
(HP1 alpha, HP1 beta, HP1 gamma),
MBD1,
TRIM28 and CDYL as partners of BAHD1.
Overexpression of BAHD1 in HEK293 cells induces large-scale chromatin condensation
and DNA methylation on autosomes.
The C-terminal
BAH domain
In molecular biology, the BAH domain (bromo-adjacent homology) domain is found in proteins such as eukaryotic DNA (cytosine-5) methyltransferases, the origin recognition complex 1 (Orc1) proteins, Bromo adjacent homology domain containing 1 (BAHD1 ...
of BAHD1 acts as a reader for the epigenetic mark
H3K27me3.
Ectopically expressed BAHD1 colocalizes with the heterochromatic inactive
X chromosome
The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and XO sex-d ...
(Xi).
Animal studies
Ablation of the ''Bahd1'' gene in the mouse alters placental development and results in hypocholesterolemia, hypoglycemia and decreased body fat.
''Bahd1''-haplodeficiency in mice decreases the efficiency of infection with the bacterial pathogen ''
Listeria monocytogenes''.
Clinical significance
During infection of human epithelial cells with the pathogen ''
Listeria monocytogenes'', BAHD1 represses
interferon-stimulated gene An interferon-stimulated gene (ISG) is a gene that can be expressed in response to stimulation by interferon. Interferons bind to receptors on the surface of a cell, initiating protein signaling pathways within the cell. This interaction leads to th ...
s.
At specific stages of infection, a ''Listeria''
nucleomodulin, LntA, acts as an inhibitor of BAHD1 and activates interferon-stimulated genes.
The BAHD1 gene is downregulated in the colon tissue in a mouse model of
ulcerative colitis.
References
Further reading
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Human proteins
{{gene-15-stub