|Coordinate||75,441,812 bp (GRCm38)|
|Base Change||A ⇒ G (forward strand)|
|Gene Name||WD repeat domain 81|
|Chromosomal Location||75,440,944-75,454,717 bp (-)|
FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a multi-domain transmembrane protein, which is predominantly expressed in the brain. Mutations in this gene are associated with autosomal recessive cerebellar ataxia, mental retardation, and dysequilibrium syndrome-2. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jun 2012]
PHENOTYPE: Mice homozygous for an ENU-induced mutation exhibit weight loss, tremors, ataxia and an abnormal gait, as well as abnormal mitochondria in Purkinje cell dendrites, Purkinje cell degeneration, photoreceptor cell loss, and decreased total retina thickness. [provided by MGI curators]
|Amino Acid Change||Leucine changed to Proline|
|Institutional Source||Beutler Lab|
|Gene Model||predicted gene model for protein(s): [ENSMUSP00000048704] [ENSMUSP00000104076] [ENSMUSP00000114450] [ENSMUSP00000120812] [ENSMUSP00000134266]|
AA Change: L1920P
AA Change: L742P
AA Change: L1921P
|Predicted Effect||probably damaging
PolyPhen 2 Score 1.000 (Sensitivity: 0.00; Specificity: 1.00)
|Alleles Listed at MGI|
|Mode of Inheritance||Autosomal Recessive|
|Local Stock||Live Mice|
|Last Updated||2018-12-18 3:14 PM by Anne Murray|
|Record Created||2016-02-19 1:39 PM by Jamie Russell|
The jello phenotype was identified among N-ethyl-N-nitrosourea (ENU)-mutagenized G3 mice of the pedigree R4351, some of which showed reduced body weights compared to wild-type littermates (Figure 1) and ataxia (Figure 2).
|Nature of Mutation|
Whole exome HiSeq sequencing of the G1 grandsire identified 40 mutations. Both of the above anomalies were linked to a mutation in Wdr81: a T to C transition at base pair 75,441,812 (v38) on chromosome 11, or base pair 12,906 in the GenBank genomic region NC_000077 encoding Wdr81. The strongest association was found with a recessive model of inheritance to the body weight phenotype, wherein three variant homozygotes departed phenotypically from six homozygous reference mice and 14 heterozygous mice with a P value of 6.295 x 10-6 (Figure 3).
The mutation corresponds to residue 6,040 in the mRNA sequence NM_138950 within exon 10 of 10 total exons.
The mutated nucleotide is indicated in red. The mutation results in a leucine (L) to proline (P) substitution at position 1,921 (L1921P) in the WDR81 protein, and is strongly predicted by PolyPhen-2 to be damaging (score = 1.000).
Wdr81 encodes the 1,934-amino acid WD repeat-containing protein 81 (WDR81). WDR81 is a member of the WD repeat protein family. The protein contains an N-terminal BEACH (Beige and Chediak-Higashi) domain (amino acids 335-612), a MFS (major facilitator superfamily) domain, and six C-terminal WD repeats (Figure 4). The function of the BEACH domain is unknown (1). WD repeats are minimally conserved regions of approximately 40 amino acids typically bracketed by Gly-His and Trp-Asp (GH-WD), which may facilitate formation of heterotrimeric or multiprotein complexes. WD repeats typically form β-sheets arranged in a seven-bladed β-propeller fold (2). Amino acids 1 to 63 are predicted to form a mitochondrion transit peptide (UniProt). In addition, amino acids 1146 to 1210 are predicted to be a Glu-rich region.
The jello mutation results in a leucine to proline substitution at amino acid 1,921, which is located within the sixth WD repeat.
WDR81 is highly expressed in Purkinje cells of the cerebellum, retinal photoreceptor cells, brain, and spinal cord (3). WDR81 is also expressed in the liver, spleen, kidney, heart, eye, sciatic nerve, and testis (3;4).
Members of the WD repeat protein family are involved in a variety of cellular processes, including cell cycle progression, signal transduction, apoptosis, and gene regulation. WDR81 functions in endosome maturation and autophagy.
Autophagy is a method of degradation that is involved in cellular maintenance and development. In canonical autophagy, a portion of the cytoplasm is sequestered within double-membrane vesicles known as autophagosomes and delivered to the lysosome whereby the contents are degraded. LC3 (microtubule-associated proteins 1A/1B light chain 3) proteins are structural proteins of autophagosomal membranes that function in the formation of the autophagosome. Phosphatidylethanolamine is covalently bound to LC3-I at the forming autophagosomse to generate LC3-II. WDR81 interacts with LC3C (microtubule-associated proteins 1A/1B light chain 3C), subsequently promoting LC3C recruitment to ubiquitinated proteins (5). WDR81 also facilitates the recognition of ubiquitinated proteins by the autophagy cargo receptor p62 (Figure 5, left) (6); loss of WDR81 expression resulted in accumulation of ubiquitinated proteins and p62 (5).
WDR81 promotes endosome maturation by interacting with WDR91 and Beclin1 in a complex that inhibits PI3K (see the record for anubis), permitting loss of phosphatidylinositol 3-phosphate and of early to late endosome conversion (Figure 5, right) (6;6;7). WDR81 cooperates with WDR91 to promote the degradation of epidermal growth factor receptor (EGFR; see the record for Velvet) as well as for trafficking and degradation of the viral restriction factor tetherin (BST2/CD317) (7). Tetherin anchors enveloped viruses to host cells and limits viral spread. Loss of WDR81 expression results in tetherin accumulation in enlarged endocytic vesicles, delayed delivery of endocytosed fluid phase cargo to lysosome, and inhibited degradation of EGFR.
Mutations in human WDR81 are associated with cerebellar ataxia, mental retardation, and dysequilibrium syndrome-2 (CAMRQ2; OMIM: #610185) (4;8-10). CAMRQ2 patients typically exhibit cerebellar ataxia, intellectual disability, sensorineural hearing loss, and mild cerebellar atrophy (11). A patient with two WDR81 nonsense mutations exhibited microcephaly, respiratory distress, lissencephaly, neonatal seizures, and bilateral ocular proptosis secondary to congenital glaucoma and facial dysmorphisms (12). Fibroblasts from the patients showed increased mitotic index and delayed prometaphase/metaphase transition (13).
Homozygous mice for an ENU-induced Wdr81 allele (Wdr81nur5/nur5) exhibited ataxia, tremors, impaired coordination, abnormal gaits, and reduced body weights compared to wild-type controls (3;14). The Wdr81nur5/nur5 mice showed loss of cerebellar granule cells, Purkinje cells, and retinal photoreceptor cells (3).
jello(F):5'- TCTCCCGAGTTTCATGAAGCC -3'
jello(R):5'- AATCCACACCTTTGACCTGTAC -3'
jello_seq(F):5'- ATTCAGGAGCTGTGCAATCC -3'
jello_seq(R):5'- ACACCTTTGACCTGTACGGCAG -3'
Genotyping is performed by amplifying the region containing the mutation using PCR, followed by sequencing of the amplified region to detect the mutation.
ICSI-R4351-jello_PCR_F: 5’- TCTCCCGAGTTTCATGAAGCC-3’
ICSI-R4351-jello_PCR_R: 5’- AATCCACACCTTTGACCTGTAC-3’
ICSI-R4351-jello_SEQ_F: 5’- ATTCAGGAGCTGTGCAATCC-3’
ICSI-R4351-jello_SEQ_R: 5’- ACACCTTTGACCTGTACGGCAG-3’
1) 94°C 2:00
2) 94°C 0:30
3) 55°C 0:30
4) 72°C 1:00
5) repeat steps (2-4) 40X
6) 72°C 10:00
7) 4°C hold
The following sequence of 401 nucleotides is amplified (NCBI RefSeq: NC_000077, chromosome 11:75441582-75441982):
tctcccgagt ttcatgaagc cacttcaagg ctttggagat tcaggagctg tgcaatccca
gacagcaggc catgtgggta gccagagcct ggggcttgcc tagaagaatc ggcttcgaga
tcaagaatga ggagcgggcc ctgagagatg tcatctcgcc ctgccctcag ccaactcctg
gctggcccta tgccaggagg cggatgatgc cattgtccga gcccagcagg aggtggcgtt
tcgtgggcag caaagccaga ctagtgagcg tgccacggaa gttctcggaa ctgagctttg
tggtggcctg agagggtggc tcaagcaggg aacagacacc aatcttgttg gctacagtgc
cggtgaccac ctcgctgccg tacaggtcaa aggtgtggat t
Primer binding sites are underlined and the sequencing primer is highlighted; the mutated nucleotide is shown in red text (Chr. (+) = A>G).
1. Nagle, D. L., Karim, M. A., Woolf, E. A., Holmgren, L., Bork, P., Misumi, D. J., McGrail, S. H., Dussault, B. J.,Jr, Perou, C. M., Boissy, R. E., Duyk, G. M., Spritz, R. A., and Moore, K. J. (1996) Identification and Mutation Analysis of the Complete Gene for Chediak-Higashi Syndrome. Nat Genet. 14, 307-311.
2. Sondek, J., Bohm, A., Lambright, D. G., Hamm, H. E., and Sigler, P. B. (1996) Crystal Structure of a G-Protein Beta Gamma Dimer at 2.1A Resolution. Nature. 379, 369-374.
3. Traka, M., Millen, K. J., Collins, D., Elbaz, B., Kidd, G. J., Gomez, C. M., and Popko, B. (2013) WDR81 is Necessary for Purkinje and Photoreceptor Cell Survival. J Neurosci. 33, 6834-6844.
4. Gulsuner, S., Tekinay, A. B., Doerschner, K., Boyaci, H., Bilguvar, K., Unal, H., Ors, A., Onat, O. E., Atalar, E., Basak, A. N., Topaloglu, H., Kansu, T., Tan, M., Tan, U., Gunel, M., and Ozcelik, T. (2011) Homozygosity Mapping and Targeted Genomic Sequencing Reveal the Gene Responsible for Cerebellar Hypoplasia and Quadrupedal Locomotion in a Consanguineous Kindred. Genome Res. 21, 1995-2003.
5. Liu, K., Jian, Y., Sun, X., Yang, C., Gao, Z., Zhang, Z., Liu, X., Li, Y., Xu, J., Jing, Y., Mitani, S., He, S., and Yang, C. (2016) Negative Regulation of Phosphatidylinositol 3-Phosphate Levels in Early-to-Late Endosome Conversion. J Cell Biol. 212, 181-198.
6. Rapiteanu, R., Davis, L. J., Williamson, J. C., Timms, R. T., Paul Luzio, J., and Lehner, P. J. (2016) A Genetic Screen Identifies a Critical Role for the WDR81-WDR91 Complex in the Trafficking and Degradation of Tetherin. Traffic. 17, 940-958.
7. Liu, X., Li, Y., Wang, X., Xing, R., Liu, K., Gan, Q., Tang, C., Gao, Z., Jian, Y., Luo, S., Guo, W., and Yang, C. (2017) The BEACH-Containing Protein WDR81 Coordinates p62 and LC3C to Promote Aggrephagy. J Cell Biol. 216, 1301-1320.
8. Turkmen, S., Demirhan, O., Hoffmann, K., Diers, A., Zimmer, C., Sperling, K., and Mundlos, S. (2006) Cerebellar Hypoplasia and Quadrupedal Locomotion in Humans as a Recessive Trait Mapping to Chromosome 17p. J Med Genet. 43, 461-464.
9. Garcias Gde, L., and Roth Mda, G. (2007) A Brazilian Family with Quadrupedal Gait, Severe Mental Retardation, Coarse Facial Characteristics, and Hirsutism. Int J Neurosci. 117, 927-933.
10. Alazami, A. M., Patel, N., Shamseldin, H. E., Anazi, S., Al-Dosari, M. S., Alzahrani, F., Hijazi, H., Alshammari, M., Aldahmesh, M. A., Salih, M. A., Faqeih, E., Alhashem, A., Bashiri, F. A., Al-Owain, M., Kentab, A. Y., Sogaty, S., Al Tala, S., Temsah, M. H., Tulbah, M., Aljelaify, R. F., Alshahwan, S. A., Seidahmed, M. Z., Alhadid, A. A., Aldhalaan, H., AlQallaf, F., Kurdi, W., Alfadhel, M., Babay, Z., Alsogheer, M., Kaya, N., Al-Hassnan, Z. N., Abdel-Salam, G. M., Al-Sannaa, N., Al Mutairi, F., El Khashab, H. Y., Bohlega, S., Jia, X., Nguyen, H. C., Hammami, R., Adly, N., Mohamed, J. Y., Abdulwahab, F., Ibrahim, N., Naim, E. A., Al-Younes, B., Meyer, B. F., Hashem, M., Shaheen, R., Xiong, Y., Abouelhoda, M., Aldeeri, A. A., Monies, D. M., and Alkuraya, F. S. (2015) Accelerating Novel Candidate Gene Discovery in Neurogenetic Disorders Via Whole-Exome Sequencing of Prescreened Multiplex Consanguineous Families. Cell Rep. 10, 148-161.
11. Komara, M., John, A., Suleiman, J., Ali, B. R., and Al-Gazali, L. (2016) Clinical and Molecular Delineation of Dysequilibrium Syndrome Type 2 and Profound Sensorineural Hearing Loss in an Inbred Arab Family. Am J Med Genet A. 170A, 540-543.
12. Cappuccio, G., Pinelli, M., Torella, A., Vitiello, G., D'Amico, A., Alagia, M., Del Giudice, E., Nigro, V., TUDP, and Brunetti-Pierri, N. (2017) An Extremely Severe Phenotype Attributed to WDR81 Nonsense Mutations. Ann Neurol. 82, 650-651.
13. Cavallin, M., Rujano, M. A., Bednarek, N., Medina-Cano, D., Bernabe Gelot, A., Drunat, S., Maillard, C., Garfa-Traore, M., Bole, C., Nitschke, P., Beneteau, C., Besnard, T., Cogne, B., Eveillard, M., Kuster, A., Poirier, K., Verloes, A., Martinovic, J., Bidat, L., Rio, M., Lyonnet, S., Reilly, M. L., Boddaert, N., Jenneson-Liver, M., Motte, J., Doco-Fenzy, M., Chelly, J., Attie-Bitach, T., Simons, M., Cantagrel, V., Passemard, S., Baffet, A., Thomas, S., and Bahi-Buisson, N. (2017) WDR81 Mutations Cause Extreme Microcephaly and Impair Mitotic Progression in Human Fibroblasts and Drosophila Neural Stem Cells. Brain. 140, 2597-2609.
14. Kile, B. T., Hentges, K. E., Clark, A. T., Nakamura, H., Salinger, A. P., Liu, B., Box, N., Stockton, D. W., Johnson, R. L., Behringer, R. R., Bradley, A., and Justice, M. J. (2003) Functional Genetic Analysis of Mouse Chromosome 11. Nature. 425, 81-86.
15. Doldur-Balli, F., Ozel, M. N., Gulsuner, S., Tekinay, A. B., Ozcelik, T., Konu, O., and Adams, M. M. (2015) Characterization of a Novel Zebrafish (Danio Rerio) Gene, wdr81, Associated with Cerebellar Ataxia, Mental Retardation and Dysequilibrium Syndrome (CAMRQ). BMC Neurosci. 16, 96-015-0229-4.
|Science Writers||Anne Murray|
|Illustrators||Diantha La Vine|
|Authors||James Butler, Sara Ludwig, Lauren Prince, Jamie Russell, Bruce Beutler, Zhao Zhang|