Alternative titles; symbols
HGNC Approved Gene Symbol: DIAPH3
Cytogenetic location: 13q21.2 Genomic coordinates (GRCh38): 13:59,665,583-60,163,928 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 13q21.2 | Auditory neuropathy, autosomal dominant 1 | 609129 | Autosomal dominant | 3 |
DIAPH3 belongs to the diaphanous subfamily of formins (see 136535). These proteins remodel the cytoskeleton by nucleating and elongating nonbranched actin filaments, and they can also bind and stabilize microtubules (summary by DeWard and Alberts, 2009).
By searching databases for the human ortholog of mouse Diaph3, Katoh and Katoh (2004) identified 2 DIAPH3 splice variants. The longer variant encodes the full-length, 1,112-amino acid protein, which contains an N-terminal FMNL (604656)-DIAPH1 (602121)-DAAM1 (606626) (FDD) domain, followed by central and C-terminal formin homology domains (FH1 and FH2, respectively). FH1 is proline-rich, and FH2 contains a putative nuclear localization signal. The shorter variant is truncated at its 5-prime end and encodes a deduced 849-amino acid protein that is N-terminally truncated relative to full-length DIAPH3. Full-length DIAPH3 shares 51.3% and 57.3% amino acid identity with DIAPH1 and DIAPH2 (300108), respectively.
Block et al. (2008) stated that full-length DRF3 contains an N-terminal GTPase-binding domain (GBD), followed by a diaphanous inhibitory domain (DID), a dimerization domain, a coiled-coil region, FH1, FH2, and a C-terminal diaphanous autoinhibitory domain (DAD). DRF3 was expressed as a cytosolic protein in transfected mouse melanoma cells. Microarray analysis revealed variable DRF3 expression in all human and mouse cell lines examined.
Using immunofluorescence microscopy, DeWard and Alberts (2009) found that DIA2 was expressed at the actin-rich cleavage furrow and microtubule-rich central spindle during cytokinesis. Western blot analysis of synchronized HeLa cells showed that DIA2 expression was high during S phase and mitosis and lower during G0 and G1 phase.
Block et al. (2008) created a constitutively active DRF3 protein, DRF3-delta-DAD, by deleting the C-terminal DAD. Overexpression of DRF3-delta-DAD in B16-F1 mouse melanoma cells resulted in dramatic induction of filopodia with club-shaped distal ends. Electron microscopy revealed that these clubs contained bundles of closely packed actin filaments, and there was a linear correlation between filopodia tip width and filament number. Bundles appeared to form by de novo nucleation. Overexpression of DRF3-delta-DAD in VA-13 human embryonic fibroblasts, which lack lamellipodia, also resulted in filopodia formation.
DeWard and Alberts (2009) stated that RHO (see 165390) small GTP-binding proteins activate diaphanous-related formins by directly binding and disrupting an intramolecular autoinhibitory interaction between N-terminal DID and C-terminal DAD. They found that DIA2 was polyubiquitinated during the cell cycle in HeLa cells and was degraded via the proteasome. Polyubiquitination of DIA2 on multiple lysines increased as cells progressed from S phase into mitosis. Microinjection of HeLa cells with mouse Dia2 lacking the GBD, DID, and DAD (Dia2-delta-GBD/delta-DAD) resulted in binucleated and multinucleated cells. Dia2-delta-GBD/delta-DAD with a point mutation that made it deficient in actin nucleation did not result in multinucleation. Expression of the isolated DAD domain in HeLa cells caused elevated actin polymerization and multinucleation. However, expression of a mutant DAD domain unable to interact with the DID domain of endogenous DIA2 resulted in significantly fewer multinucleated cells. DeWard and Alberts (2009) concluded that DIA2 ubiquitination and degradation may contribute to the disassembly of the contractile ring during cytokinesis.
Katoh and Katoh (2004) determined that the DIAPH3 gene contains 28 exons, including an alternative first exon, exon 1b. Exon 1b is located between exons 7 and 8 and is used by the 5-prime truncated DIAPH3 splice variant.
By genomic sequence analysis, Katoh and Katoh (2004) mapped the DIAPH3 gene to chromosome 13q21.2.
In affected members of a family with autosomal dominant auditory neuropathy mapping to chromosome 13q21 (AUNA1; 609129) originally reported by Kim et al. (2004), Schoen et al. (2010) identified a heterozygous mutation (c.-172G-A) in the 5-prime untranslated region (UTR) of the DIAPH3 gene that resulted in increased mRNA and protein expression. Drosophila with constitutive overexpression of a mutant Diaph gene in the auditory organ had reduced sound-evoked potentials. The findings indicated that AUNA1 is caused by overexpression of the DIAPH3 gene due to a mutation in a transcriptional regulatory site, consistent with a gain of function.
In a Spanish family in which a father and 2 children had auditory neuropathy, Sanchez-Martinez et al. (2017) identified a heterozygous mutation in the 5-prime UTR of the DIAPH3 gene (c.173C-T; 614567.0002), adjacent to the previously reported AUNA1-associated mutation. The mutation segregated with disease in the family.
In a study of 1,751 knockout alleles created by the International Mouse Phenotyping Consortium (IMPC), Dickinson et al. (2016) found that knockout of the mouse homolog of human DIAPH3 is homozygous-lethal (defined as absence of homozygous mice after screening of at least 28 pups before weaning).
In affected members of a family with autosomal dominant auditory neuropathy-1 (AUNA1; 609129), Schoen et al. (2010) identified a heterozygous G-to-A transition at position -172 in the 5-prime untranslated region of the DIAPH3 gene (c.-172G-A, NM_001042517). The mutation occurred in a highly conserved region and was not found in 758 control chromosomes. Two individuals were homozygous for the mutation. Analysis of patient lymphoblastoid cells showed that heterozygotes and homozygotes had a 2.11- and 2.98-fold increased expression of DIAPH3, respectively, compared to controls. The difference between heterozygote and homozygote expression was not statistically significant. Increased expression correlated with increased protein levels (1.48- to 1.68-fold in heterozygotes and homozygotes, respectively). In vitro studies showed that the mutation was sufficient to drive overexpression of a luciferase reporter. Drosophila with constitutive overexpression of a mutant Diaph gene in the auditory organ had reduced sound-evoked potentials. The findings indicated that AUNA1 is caused by overexpression of the DIAPH3 gene due to a mutation in a transcriptional regulatory site, consistent with a gain of function.
In a father and 2 children from a Spanish family with auditory neuropathy (AUNA1; 609129), Sanchez-Martinez et al. (2017) identified heterozygosity for a c.-173C-T transition involving the highly conserved central cytosine within the GC box consensus sequence in the 5-prime UTR of the DIAPH3 gene. The mutation was not found in the unaffected mother or an unaffected sister.
Block, J., Stradal, T. E. B., Hanisch, J., Geffers, R., Kostler, S. A., Urban, E., Small, J. V., Rottner, K., Faix, J. Filopodia formation induced by active mDia2/Drf3. J. Microsc. 231: 506-517, 2008. [PubMed: 18755006] [Full Text: https://doi.org/10.1111/j.1365-2818.2008.02063.x]
Deward, A. D., Alberts, A. S. Ubiquitin-mediated degradation of the formin mDia2 upon completion of cell division. J. Biol. Chem. 284: 20061-20069, 2009. [PubMed: 19457867] [Full Text: https://doi.org/10.1074/jbc.M109.000885]
Dickinson, M. E., Flenniken, A. M., Ji, X., Teboul, L., Wong, M. D., White, J. K., Meehan, T. F., Weninger, W. J., Westerberg, H., Adissu, H., Baker, C. N., Bower, L., and 73 others. High-throughput discovery of novel developmental phenotypes. Nature 537: 508-514, 2016. Note: Erratum: Nature 551: 398 only, 2017. [PubMed: 27626380] [Full Text: https://doi.org/10.1038/nature19356]
Katoh, M., Katoh, M. Identification and characterization of human DIAPH3 gene in silico. Int. J. Molec. Med. 13: 473-478, 2004. [PubMed: 14767582]
Kim, T. B., Isaacson, B., Sivakumaran, T. A., Starr, A., Keats, B. J. B., Lesperance, M. M. A gene responsible for autosomal dominant auditory neuropathy (AUNA1) maps to 13q14-21. J. Med. Genet. 41: 872-876, 2004. [PubMed: 15520414] [Full Text: https://doi.org/10.1136/jmg.2004.020628]
Sanchez-Martinez, A., Benito-Orejas, J. I., Telleria-Orriols, J. J., Alonso-Ramos, M. J. Autosomal dominant auditory neuropathy and variant DIAPH3 (c.-173C>T). Acta Otorrinolaring. Esp. (Engl. Ed.) 68: 183-185, 2017. [PubMed: 27658576] [Full Text: https://doi.org/10.1016/j.otorri.2016.06.004]
Schoen, C. J., Emery, S. B., Thorne, M. C., Ammana, H. R., Sliwerska, E., Arnett, J., Hortsch, M., Hannan, F., Burmeister, M., Lesperance, M. M. Increased activity of Diaphanous homolog 3 (DIAPH3)/diaphanous causes hearing defects in humans with auditory neuropathy and in Drosophila. Proc. Nat. Acad. Sci. 107: 13396-13401, 2010. [PubMed: 20624953] [Full Text: https://doi.org/10.1073/pnas.1003027107]