Alternative titles; symbols
HGNC Approved Gene Symbol: NUP85
Cytogenetic location: 17q25.1 Genomic coordinates (GRCh38): 17:75,205,679-75,235,758 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 17q25.1 | Nephrotic syndrome, type 17 | 618176 | Autosomal recessive | 3 |
Bidirectional transport of macromolecules between the cytoplasm and nucleus occurs through nuclear pore complexes (NPCs) embedded in the nuclear envelope. NPCs are composed of subcomplexes, and NUP85 is part of one such subcomplex, NUP107 (607617)-NUP160 (607614) (Loiodice et al., 2004).
Doxsey et al. (1994) used antisera from scleroderma patients that react widely with centrosomes in plants and animals to isolate cDNAs encoding a novel centrosomal protein. The nucleotide sequence was consistent with a 7-kb mRNA and contained an open reading frame encoding a protein with a putative large coiled-coil domain flanked by noncoiled ends. Antisera recognized a 220-kD protein and stained centrosomes and acentriolar microtubule-organizing centers, where the protein was localized to the pericentriolar material. Because of these characteristics, Doxsey et al. (1994) proposed the name pericentrin.
By proteomic analysis and mass spectrometry, Cronshaw et al. (2002) identified 94 proteins associated with NPCs purified from rat liver nuclei. Database analysis identified FLJ12549, which Cronshaw et al. (2002) called NUP75, as the human homolog of a rat protein found in relative abundance, with 16 copies per NPC. The deduced human protein has a calculated molecular mass of 75 kD and is homologous to the yeast Nup85 protein.
Using a yeast 2-hybrid screen of a human myelomonocytic leukemia THP-1 cell cDNA library using the C-terminal domain of CCR2 (601267) as bait, followed by screening a THP-1 cell cDNA library, Terashima et al. (2005) cloned full-length NUP85, which they called FROUNT. The deduced 656-amino acid protein contains a leucine zipper motif, 4 tyrosine-based motifs, 4 dileucine signals, and a conserved clathrin heavy chain (CLTC; 118955) repeat (CHCR) homology domain. Human and mouse FROUNT share 92% amino acid identity. Database analysis identified FROUNT orthologs in fly, worm, plant, and yeast. Hydrophobicity profiling indicated that FROUNT was a cytoplasmic protein. RNA blot analysis detected a 2.6-kb FROUNT transcript in human blood monocytes and mouse peritoneal cells.
Doxsey et al. (1994) found that anti-pericentrin antibodies disrupted mitotic and meiotic divisions in vivo and blocked microtubule aster formation in Xenopus extracts, but did not block gamma-tubulin assembly or microtubule nucleation from mature centrosomes. Thus, pericentrin is probably a conserved integral component of the filamentous matrix of the centrosome involved in the initial establishment of organized microtubule arrays.
Using antibodies directed against fluorescence-tagged NUP107, Loiodice et al. (2004) confirmed that NUP85 is a constituent of the Nup107-160 complex.
Zuccolo et al. (2007) stated that the NUP107-NUP160 nucleoporin subcomplex contains NUP133 (607613), NUP96 (601021), NUP85, NUP43 (608141), NUP37 (609264), SEC13 (SEC13L1; 600152), and SEH1 (SEH1L; 609263). The NUP107-NUP160 subcomplex stably associates on both faces of NPCs during interphase, and the entire subcomplex is recruited to chromatin during mitosis. A fraction of the subcomplex localizes at kinetochores during prophase, even before nuclear envelope breakdown. Zuccolo et al. (2007) found that recruitment of the NUP107-NUP160 complex to kinetochores depended mainly on the NDC80 complex (see 607272) and CENPF (600236). The SEH1 subunit of the NUP107-NUP160 complex was essential for targeting the complex to kinetochores. Codepletion of several NUP107-NUP160 subunits or of SEH1 alone resulted in kinetochores that failed to establish proper microtubule attachment, thus inducing a checkpoint-dependent mitotic delay. The mitotic Ran-GTP effector, CRM1 (XPO1; 602559), as well as its binding partner, the RANGAP1 (602362)-RANBP2 (601181) complex, were mislocalized upon depletion of NUP107-NUP160 complex from kinetochores.
Using yeast 2-hybrid and coimmunoprecipitation analyses and fluorescence microscopy, Terashima et al. (2005) showed that human FROUNT bound to the membrane-proximal C-terminal domain of activated CCR2 and facilitated cluster formation at the cell front during chemotaxis. Overexpression amplified the chemokine-elicited PI3K (see 601232)-RAC (602048)-lamellipodium protrusion cascade and subsequent chemotaxis, whereas blocking FROUNT by using a truncated mutant or antisense strategy diminished CCR2 signaling. Suppression of Frount in a mouse model of peritonitis inhibited macrophage infiltration. Terashima et al. (2005) proposed that FROUNT may be a therapeutic target in chronic inflammatory diseases.
By phylogenetic analysis, Toda et al. (2009) found that the C-terminal region of CCR5 (601373) has high homology to that of CCR2. Yeast 2-hybrid and coimmunoprecipitation analyses demonstrated that the CCR2-binding domain of FROUNT bound to the C termini of CCR2 and CCR5, but not to those of CCR1 (601159), CCR3 (601268), or CXCR4 (162643). CCL4 (182284), a CCR5 ligand, induced chemotaxis in cells expressing CCR5 and intact FROUNT. Toda et al. (2009) concluded that FROUNT is a common regulator of CCR2 and CCR5.
Crystal Structure
In Saccharomyces cerevisiae, Nup85 and Seh1 (609263) constitute a module in the heptameric Nup84 (NUP107) complex. Brohawn et al. (2008) determined the structure of a complex of S. cerevisiae Nup85 residues 1 to 564 (of 744) and intact Seh1 at 3.5-angstrom resolution. Structural, biochemical, and genetic analyses positioned the Nup84 complex in 2 peripheral nuclear pore complex rings. Brohawn et al. (2008) established a conserved tripartite element, the ancestral coatomer element ACE1, that reoccurs in several nucleoporins and vesicle coat proteins, providing structural evidence of coevolution from a common ancestor. They identified interactions that define the organization of the Nup84 complex on the basis of comparison with vesicle coats and confirmed the sites by mutagenesis. Brohawn et al. (2008) proposed that the nuclear pore complex scaffold, like vesicle coats, is composed of polygons with vertices and edges forming a membrane-proximal lattice that provides docking sites for additional nucleoporins.
Scott (2001) mapped the NUP85 gene to chromosome 17q25 based on sequence similarity between the NUP85 sequence (GenBank AI970199) and a chromosome 17 clone (GenBank AC022211).
Terashima et al. (2005) stated that NUP85 maps to chromosome 17q25.1, near the CCL2 gene (158105).
In 4 patients from 3 unrelated families with nephrotic syndrome type 17 (NPHS17; 618176), Braun et al. (2018) identified homozygous or compound heterozygous mutations in the NUP85 gene (170285.0001-170285.0004). The mutations were found by high-throughput targeted exon sequencing and were demonstrated to segregate in the 2 families from which parental DNA was available for study. In vitro functional expression studies showed that most of the mutations weakened the interaction of NUP85 with NUP160 (607614) and were unable to fully rescue abnormal kidney morphology in nup85-null Xenopus embryos, consistent with a loss of function. CRISPR/Cas9-mediated knockout of NUP85 in human podocytes increased the formation of filopodia and was associated with increased Cdc42 (116952) activity, suggesting alteration of actin and cytoskeletal dynamics. CRISPR/Cas9-mediated knockout of the nup85 gene in zebrafish embryos resulted in developmental abnormalities, including small eyes, body axis curvature, and edema, as well as early lethality.
Braun et al. (2018) found that morpholino knockdown of nup85 in Xenopus embryos resulted in abnormal pronephros morphology, consistent with a defect in glomerulogenesis. Expression of human wildtype NUP85 rescued the defect. CRISPR/Cas9-mediated knockout of the nup85 gene in zebrafish embryos resulted in developmental abnormalities, including small eyes, body axis curvature, and edema, as well as early lethality.
In an 8-year-old girl (A5195), born of consanguineous Egyptian parents, with nephrotic syndrome type 17 (NPHS17; 618176), Braun et al. (2018) identified a homozygous c.1430C-T transition (c.1430C-T, NM_024844.4) in exon 15 of the NUP85 gene, resulting in an ala477-to-val (A477V) substitution at a highly conserved residue. The mutation was found by high-throughput targeted exon sequencing. The variant was not found in the gnomAD database. The patient had a deceased sister with a similar phenotype; DNA from the sister and parents was not available for segregation studies. Expression of A477V mRNA into nup85-null Xenopus embryos partially rescued the abnormal kidney morphology, suggesting that this allele may have some residual function.
In an 11-year-old boy (A3259), born of unrelated Arab parents, with nephrotic syndrome type 17 (NPHS17; 618176), Braun et al. (2018) identified a homozygous c.1933C-T transition (c.1933C-T, NM_024844.4) in exon 19 of the NUP85 gene, resulting in an arg645-to-trp (R645W) substitution at a highly conserved residue. The mutation, which was found by high-throughput targeted exon sequencing, segregated with the disorder in the family. The variant was found at a low frequency in heterozygous state in the gnomAD database (10 of 277,224 alleles). In vitro functional expression studies showed that the R645W mutation weakened the interaction of NUP85 with NUP160 (607614). Expression of R645W mRNA into nup85-null Xenopus embryos was unable to rescue the abnormal kidney morphology, suggesting that it causes a loss of function.
In 2 sibs (NCR3227/NCR3310), born of unrelated parents of European origin, with nephrotic syndrome type 17 (NPHS17; 618176), Braun et al. (2018) identified compound heterozygous mutations in the NUP85 gene: a G-to-A transition in intron 5 (c.405+1G-A, NM_024844.4), resulting in a splice site alteration, and a c.1741G-C transversion in exon 17, resulting in an ala581-to-pro (A581P; 170285.0004) substitution at a highly conserved residue. The mutations, which were found by high-throughput targeted exon sequencing, segregated with the disorder in the family. Neither variant was found in the gnomAD database. The splice site mutation was predicted to result in the skipping of exon 5, causing a frameshift and premature termination. In vitro functional expression studies showed that both mutations weakened the interaction of NUP85 with NUP160 (607614). Expression of mutant mRNA into nup85-null Xenopus embryos was unable to rescue the abnormal kidney morphology, suggesting that both alleles cause a loss of function.
For discussion of the c.1741G-C transversion (c.1741G-C, NM_024844.4) in exon 17 of the NUP85 gene, resulting in an ala581-to-pro (A581P) substitution, that was found in compound heterozygous state in 2 sibs with nephrotic syndrome, type 17 (NPHS17; 618176) by Braun et al. (2018), see 170285.0003.
Braun, D. A., Lovric, S., Schapiro, D., Schneider, R., Marquez, J., Asif, M., Hussain, M. S., Daga, A., Widneier, E., Rao, J., Ashraf, S., Tan, W., and 46 others. Mutations in multiple components of the nuclear pore complex cause nephrotic syndrome. J. Clin. Invest. 128: 4313-4328, 2018. [PubMed: 30179222] [Full Text: https://doi.org/10.1172/JCI98688]
Brohawn, S. G., Leksa, N. C., Spear, E. D., Rajashankar, K. R., Schwartz, T. U. Structural evidence for common ancestry of the nuclear pore complex and vesicle coats. Science 322: 1369-1373, 2008. [PubMed: 18974315] [Full Text: https://doi.org/10.1126/science.1165886]
Cronshaw, J. M., Krutchinsky, A. N., Zhang, W., Chait, B. T., Matunis, M. J. Proteomic analysis of the mammalian nuclear pore complex. J. Cell Biol. 158: 915-927, 2002. [PubMed: 12196509] [Full Text: https://doi.org/10.1083/jcb.200206106]
Doxsey, S. J., Stein, P., Evans, L., Calarco, P. D., Kirschner, M. Pericentrin, a highly conserved centrosome protein involved in microtubule organization. Cell 76: 639-650, 1994. [PubMed: 8124707] [Full Text: https://doi.org/10.1016/0092-8674(94)90504-5]
Loiodice, I., Alves, A., Rabut, G., van Overbeek, M., Ellenberg, J., Sibarita, J.-B., Doye, V. The entire Nup107-160 complex, including three new members, is targeted as one entity to kinetochores in mitosis. Molec. Biol. Cell 15: 3333-3344, 2004. [PubMed: 15146057] [Full Text: https://doi.org/10.1091/mbc.e03-12-0878]
Scott, A. F. Personal Communication. Baltimore, Md. 5/11/2001.
Terashima, Y., Onai, N., Murai, M., Enomoto, M., Poonpiriya, V., Hamada, T., Motomura, K., Suwa, M., Ezaki, T., Haga, T., Kanegasaki, S., Matsushima, K. Pivotal function for cytoplasmic protein FROUNT in CCR2-mediated monocyte chemotaxis. Nature Immun. 6: 827-835, 2005. [PubMed: 15995708] [Full Text: https://doi.org/10.1038/ni1222]
Toda, E., Terashima, Y., Sato, T., Hirose, K., Kanegasaki, S., Matsushima, K. FROUNT is a common regulator of CCR2 and CCR5 signaling to control directional migration. J. Immun. 183: 6387-6394, 2009. [PubMed: 19841162] [Full Text: https://doi.org/10.4049/jimmunol.0803469]
Zuccolo, M., Alves, A., Galy, V., Bolhy, S., Formstecher, E., Racine, V., Sibarita, J.-B., Fukagawa, T., Shiekhattar, R., Yen, T., Doye, V. The human Nup107-160 nuclear pore subcomplex contributes to proper kinetochore functions. EMBO J. 26: 1853-1864, 2007. [PubMed: 17363900] [Full Text: https://doi.org/10.1038/sj.emboj.7601642]