Genes in the ''DLX'' family encode

homeodomain A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full ...

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...

s related to the ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'' distal-less ''(Dll)'' gene. The family has been related to a number of developmental features such as jaws and limbs. The family seems to be well preserved across species. As ''DLX''/''Dll'' are involved in limb development in most of the major phyla, including vertebrates, it has been suggested that ''Dll'' was involved in appendage growth in an early bilaterial ancestor. Six members of the family are found in human and mice, numbered DLX1 to DLX6. They form two-gene

cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft), a European Space Agency mission to study t ...

s (bigene clusters) with each other. There are

DLX1 Homeobox protein DLX-1 is a protein that in humans is encoded by the ''DLX1'' gene. Function This gene encodes a member of a homeobox transcription factor gene family similar to the ''Drosophila'' distal-less gene. The encoded protein is locali ...

DLX2 Homeobox protein DLX-2 is a protein that in humans is encoded by the ''DLX2'' gene. Many vertebrate homeo box-containing genes have been identified on the basis of their sequence similarity with Drosophila developmental genes. Members of the Dlx ...

DLX3 Homeobox protein DLX-3 is a protein that in humans is encoded by the ''DLX3'' gene. Function Dlx3 is a crucial regulator of hair follicle differentiation and cycling. Dlx3 transcription is mediated through Wnt, and colocalization of Dlx3 wit ...

DLX4 Homeobox protein DLX-4 is a protein that in humans is encoded by the ''DLX4'' gene. Function Many vertebrate homeobox-containing genes have been identified on the basis of their sequence similarity with ''Drosophila'' developmental genes. Memb ...

DLX5 Homeobox protein DLX-5 is a protein that in humans is encoded by the distal-less homeobox 5 gene, or ''DLX5'' gene. DLX5 is a member of DLX gene family. Function This gene encodes a member of a homeobox transcription factor gene family similar ...

DLX6 Homeobox protein DLX-6 is a protein that in humans is encoded by the ''DLX6'' gene. This gene encodes a member of a homeobox transcription factor gene family similar to the Drosophila ''Drosophila'' () is a genus of flies, belonging to the ...

clusters in vertebrates, linked to

Hox gene Hox genes, a subset of homeobox genes, are a group of related genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Hox proteins encode and specify the characteristics of 'position', ensuring that the cor ...

clusters HOXD, HOXB, and HOXA respectively. In higher fishes like the

zebrafish The zebrafish (''Danio rerio'') is a freshwater fish belonging to the minnow family ( Cyprinidae) of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often ...

, there are two additional ''DLX'' genes, ''dlx2b'' (''dlx5'') and ''dlx4a'' (''dlx8''). These additional genes are not linked with each other, or any other ''DLX'' gene. All six other genes remain in bigene clusters. ''

, DLX7, DLX8'' and ''DLX9'' are the same gene in vertebrates. They are named differently because every time the same gene was found, the researchers thought they had found a new gene.

Function

''DLX'' genes, like ''distal-less'', are involved in limb development in most of the major phyla. ''DLX'' genes are involved in craniofacial morphogenesis and the tangential migration of interneurons from the subpallium to the

pallium The pallium (derived from the Roman ''pallium'' or ''palla'', a woolen cloak; : ''pallia'') is an ecclesiastical vestment in the Catholic Church, originally peculiar to the pope, but for many centuries bestowed by the Holy See upon metropol ...

during vertebrate

brain development The development of the nervous system, or neural development (neurodevelopment), refers to the processes that generate, shape, and reshape the nervous system of animals, from the earliest stages of embryonic development to adulthood. The fiel ...

. It has been suggested that ''DLX'' promotes the migration of interneurons by repressing a set of proteins that are normally expressed in terminally differentiated neurons and act to promote the outgrowth of

dendrite Dendrites (from Greek δένδρον ''déndron'', "tree"), also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the ...

s and

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...

s. Mice lacking DLX1 exhibit electrophysiological and histological evidence consistent with delayed-onset

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...

. DLX2 has been associated with a number of areas including development of the

zona limitans intrathalamica The ''zona limitans intrathalamica'' (ZLI) is a lineage-restriction compartment and primary developmental boundary in the vertebrate forebrain (which is analogous to the human cerebrum) that serves as a signaling center and a restrictive border bet ...

and the

prethalamus The subthalamus or prethalamus is a part of the diencephalon. Its most prominent structure is the subthalamic nucleus. The subthalamus connects to the globus pallidus, a basal nucleus of the telencephalon. Structure The subthalamus is located ...

. DLX4 (DLX7) is expressed in

bone marrow Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...

. ''DLX5'' and ''DLX6'' genes are necessary for normal formation of the mandible in vertebrates.

References

{{genarch Gene families Transcription factors