Alternative titles; symbols
HGNC Approved Gene Symbol: DNER
Cytogenetic location: 2q36.3 Genomic coordinates (GRCh38) : 2:229,357,629-229,714,555 (from NCBI)
The DNER gene encodes a transmembrane protein carrying extracellular EGF repeats and is strongly expressed in Purkinje cells in the cerebellum. DNER functions as a Notch (190198) ligand and mediates signaling through neuron-glia interactions (Eiraku et al. (2002, 2005)).
Using subtractive hybridization to identify genes that are differentially expressed during the development of mouse cerebellar granule cells, Eiraku et al. (2002) identified and cloned Dner, which was strongly expressed during formation of dendrites and axons. Using the mouse cDNA as probe, Eiraku et al. (2002) cloned human DNER from a brain cDNA library. The deduced human and mouse proteins contain 737 amino acids and share 90% identity. DNER contains an N-terminal signal sequence and 10 distinct EGF (131530)-like motifs. The final EGF-like repeat displays a typical signature of a calcium-binding domain important for molecular orientation. DNER also has a single transmembrane region and an intracellular C-terminal region containing potential tyrosine kinase phosphorylation sites, a typical tyrosine-based sorting signal (YEEF), and a dileucine-type sorting signal (LI). Northern blot analysis of several mouse tissues revealed a 3.7-kb transcript that was predominantly expressed in brain. Western blot analysis of mouse brain lysates revealed a molecular mass of about 90 kD, with 2 higher molecular mass species occasionally detected. In situ hybridization revealed that Dner mRNA was almost exclusively expressed in the mouse central nervous system as early as embryonic day 14.5. Immunolocalization of Dner protein revealed expression in several types of neurons, including cortical and hippocampal pyramidal neurons, cerebellar granule cells, and Purkinje cells. Dner localized to the dendritic plasma membrane and within endosomes, and it was excluded from the axons even when experimentally overexpressed.
Using deletion and mutation analysis, Eiraku et al. (2002) determined that the YEEF tyrosine-based motif is required for somatodendritic targeting of mouse Dner. Using coimmunoprecipitation techniques, they found direct binding between Dner and the clathrin coat-associated protein complex Ap1 (see 603534), and they colocalized Dner and Ap1 within mouse Purkinje cells. Eiraku et al. (2002) concluded that Dner undergoes Ap1-dependent sorting to the somatodendritic compartments from the trans-Golgi network.
Differentiation of glia in the central nervous system is regulated by Notch (see NOTCH1; 190198) signaling through neuron-glia interaction. Eiraku et al. (2005) identified Dner as a ligand of Notch during cellular morphogenesis of Bergmann glia in the mouse cerebellum. Dner bound to Notch1 at cell-cell contacts and activated Notch signaling in vitro. In the developing cerebellum, Dner was highly expressed in Purkinje cell dendrites, which were tightly associated with radial fibers of Bergmann glia expressing Notch. Dner specifically bound to Bergmann glia in culture and induced process extension by activating gamma-secretase (see PSEN1; 104311)- and Dtx1 (602582)-dependent Notch signaling. Inhibition of Dtx1-dependent but not Rbpj (RBPSUH; 147183)-dependent Notch signaling in Bergmann glia suppressed formation and maturation of radial fibers in organotypic slice cultures. Additionally, deficiency of Dner retarded the formation of radial fibers and resulted in abnormal arrangement of Bergmann glia.
Paraneoplastic Tr Antibody
Graus et al. (1997) characterized the anti-Tr antibody found in the serum and cerebrospinal fluid of 5 patients with paraneoplastic cerebellar degeneration and Hodgkin lymphoma. The name 'Tr' was given because the antibody was first identified by Trotter et al. (1976) in a woman with subacute cerebellar degeneration associated with Hodgkin lymphoma. The antibody reacted with cerebellar Purkinje cells. Graus et al. (1997) found that anti-Tr antibodies labeled the cytoplasm of Purkinje cells of human and rat cerebellum. The molecular layer of rat cerebellum showed a characteristic dotted pattern suggestive of immunoreactivity of dendritic spines of Purkinje cells. Anti-Tr antibodies were not found in 159 patients with cerebellar disorders without Hodgkin disease or in 30 patients with Hodgkin disease without cerebellar disorders. Thus, anti-Tr antibodies appeared specific for Hodgkin-associated paraneoplastic cerebellar degeneration.
De Graaff et al. (2012) identified DNER as the antigen for the anti-Tr antibody that can cause paraneoplastic cerebellar degeneration and is usually associated with Hodgkin lymphoma. The protein was identified by mass spectrometry analysis of immunopurified rat brain treated with anti-Tr-positive sera. All 12 anti-Tr-positive sera stained DNER-expressing HeLa cells, and all but 1 of 246 control sera samples did not stain DNER-expressing HeLa cells. Studies with deletion constructs localized the main epitope to the extracellular domain. Knockdown of endogenous DNER in cultured hippocampal neurons and mutating its N-glycosylation sites abolished the anti-Tr staining, indicating that glycosylation of DNER is required for it to be recognized by the antibody. Western blotting was an unreliable method for diagnosing anti-Tr antibodies.
By genomic sequence analysis, Eiraku et al. (2002) mapped the DNER gene to chromosome 2q37.
Tohgo et al. (2006) found that Dner-knockout mice showed motor incoordination in the fixed bar and rotarod tests. The cerebellum from these mice was small with hypoplasia of the cerebellar fissure and folia, indicating impaired development. Histochemical and electrophysiologic analyses showed that Purkinje cells had normal differentiation and formation of synapses, but there was irregular multiple innervation of Purkinje cells by climbing fibers and irregular parallel fiber/Purkinje cell transmission. This was associated with impaired glutamate clearance at the parallel fiber-Purkinje cell synapses, likely resulting from reduced GLAST (SLC1A3; 600111) content in Bergmann glia. The findings indicated that DNER takes part in stimulation of maturation of the cerebellum via intercellular communication between Purkinje cells and Bergmann glia and is essential for precise cerebellar functional and morphologic development.
de Graaff, E., Maat, P., Hulsenboom, E., van den Berg, R., van den Bent, M., Demmers, J., Lugtenburg, P. J., Hoogenraad, C. C., Sillevis Smitt, P. Identification of delta/notch-like epidermal growth factor-related receptor as the Tr antigen in paraneoplastic cerebellar degeneration. Ann. Neurol. 71: 815-824, 2012. [PubMed: 22447725] [Full Text: https://doi.org/10.1002/ana.23550]
Eiraku, M., Hirata, Y., Takeshima, H., Hirano, T., Kengaku, M. Delta/Notch-like epidermal growth factor-related receptor, a novel EGF-like repeat-containing protein targeted to dendrites of developing and adult central nervous system neurons. J. Biol. Chem. 277: 25400-25407, 2002. [PubMed: 11950833] [Full Text: https://doi.org/10.1074/jbc.M110793200]
Eiraku, M., Tohgo, A., Ono, K., Kaneko, M., Fujishima, K., Hirano, T., Kengaku, M. DNER acts as a neuron-specific Notch ligand during Bergmann glial development. Nature Neurosci. 8: 873-880, 2005. [PubMed: 15965470] [Full Text: https://doi.org/10.1038/nn1492]
Graus, F., Dalmau, J., Valldeoriola, F., Ferrer, I., Rene, R., Marin, C., Vecht, C. J., Arbizu, T., Targa, C., Moll, J. W. B. Immunological characterization of a neuronal antibody (anti-Tr) associated with paraneoplastic cerebellar degeneration and Hodgkin's disease. J. Neuroimmun. 74: 55-61, 1997. [PubMed: 9119979] [Full Text: https://doi.org/10.1016/s0165-5728(96)00205-6]
Tohgo, A., Eiraku, M., Miyazaki, T., Miura, E., Kawaguchi, S., Nishi, M., Watanabe, M., Hirano, T., Kengaku, M., Takeshima, H. Impaired cerebellar functions in mutant mice lacking DNER. Molec. Cell Neurosci. 31: 326-333, 2006. [PubMed: 16298139] [Full Text: https://doi.org/10.1016/j.mcn.2005.10.003]
Trotter, J. L., Hendin, B. A., Osterland, K. Cerebellar degeneration with Hodgkin disease: an immunological study. Arch. Neurol. 33: 660-661, 1976. [PubMed: 962649] [Full Text: https://doi.org/10.1001/archneur.1976.00500090066014]