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|Mutation Type||splice donor site|
|Coordinate||126,920,313 bp (GRCm38)|
|Base Change||C ⇒ T (forward strand)|
|Gene Name||signal peptide peptidase like 2A|
|Chromosomal Location||126,890,391-126,933,235 bp (-)|
|MGI Phenotype||Mice homozygous for a knock-out allele exhibit decreased immunoglobulin prior to and after immunization and decreased splenic B cells, myeloid dendritic cells, T2 B cells and follicular B cells. Mice homozygous for a hypomorphic allele exhibit similar albeit less severe phenotypes.|
|Limits of the Critical Region||126890391 - 126933235 bp|
|Amino Acid Change|
|Institutional Source||Beutler Lab|
|Gene Model||predicted gene model for protein(s): [ENSMUSP00000028844]|
|Predicted Effect||probably null|
|Phenotypic Category||T-dependent humoral response defect- decreased antibody response to OVA+ alum immunization, T-dependent humoral response defect- decreased antibody response to rSFV, T-independent B cell response defect- decreased TNP-specific IgM to TNP-Ficoll immunization|
|Alleles Listed at MGI|
|Mode of Inheritance||Autosomal Recessive|
|Last Updated||10/28/2016 2:15 PM by Anne Murray|
|Record Created||06/23/2016 10:42 PM by Jin Huk Choi|
The abra2 phenotype was identified among G3 mice of the pedigree R4653, some of which showed diminished T-dependent antibody response to ovalbumin administered with aluminum hydroxide (Figure 1) and to recombinant Semliki Forest virus (rSFV)-encoded β-galactosidase (rSFV-β-gal) (Figure 2) were diminished. The T-independent antibody response to 4-hydroxy-3-nitrophenylacetyl-Ficoll (NP-Ficoll) was also diminished (Figure 3).
|Nature of Mutation|
Whole exome HiSeq sequencing of the G1 grandsire identified 62 mutations. All of the above anomalies were linked by continuous variable mapping to a mutation in three genes on chromosome 2: Ext2, Ryr3, and Sppl2a. The Sppl2a mutation is presumed causative, because the immune phenotypes observed in abra2 mimic those listed on MGI and another Sppl2a mutant identified in a second pedigree (see abra). The Sppl2a mutation is a G to A transition at base pair 126,920,313 (v38) on chromosome 2, or base pair 12,950 in the GenBank genomic region NC_000068 encoding the Sppl2a gene. The strongest association was found with a recessive model of linkage to the normalized antibody response to rSFV-β-gal (P = 7.067 x 10-15), wherein four variant homozygotes departed phenotypically from four homozygous reference mice and four heterozygous mice (Figure 4).
The effect of the mutation at the cDNA and protein level have not examined, but the mutation is predicted to result in the use of a cryptic site in intron 7. Use of the cryptic splice site would result in a 54-base pair insertion in intron 7, leading to a frame-shifted protein product beginning after amino acid 281, and termination after the inclusion of 9 aberrant amino acids.
Genomic numbering corresponds to NC_000068. The donor splice site of intron 7, which is destroyed by the abra2 mutation, is indicated in blue lettering and the mutated nucleotide is indicated in red.
Sppl2a encodes SPPL2a, a signal peptide peptidase-like (SPPL) protease, and member of the GxGD intramembrane-cleaving protease family of aspartyl intramembrane-cleaving proteases (I-CLiPs) (Figure 5). SPPL proteins share a YD motif (amino acids 354-355), a GXGD motif (amino acids 413-416), and a PAL sequence (amino acids 466-468) (1-4). SPPL2A has nine transmembrane domains. The abra2 mutation is within intron 7.
For more information about Sppl2a, please see the record for abra.
GxGD proteases are essential for the regulated intramembrane proteolysis (RIP) of single span type II transmembrane proteins. SPPL2A cleaves TNF-α (see the record for PanR1; (5)), ITM2B (Bri2) (6), Fas ligand (FasL; see the record for riogrande) (7), CD74 (8-13), TMEM106B (14), and neuregulin 1 type III (15).
Sppl2a knockout (Sppl2a-/-) mice have a developmental block during the splenic phase of B cell maturation. As a result, the frequency of mature and functionally competent B cells is reduced, and the mice exhibit impaired humoral immune responses (8). Abra2 mice exhibited defects in the T-independent B cell response to NP-Ficoll as well as T-dependent antibody responses to rSFV-β-gal and OVA-alum. Taken together, the abra2 mutation results in loss of SPPL2A function.
abra2(F):5'- TCAGGAATTCAGTGTAAAGATCCC -3'
abra2(R):5'- AGACTCTTGGTTGCGCCTTAG -3'
abra2_seq(F):5'- CCTTTAAGTCCTAGCACTGAGGTAG -3'
abra2_seq(R):5'- TGCGCCTTAGCAACTGC -3'
1. Weihofen, A., Binns, K., Lemberg, M. K., Ashman, K., and Martoglio, B. (2002) Identification of Signal Peptide Peptidase, a Presenilin-Type Aspartic Protease. Science. 296, 2215-2218.
2. Ponting, C. P., Hutton, M., Nyborg, A., Baker, M., Jansen, K., and Golde, T. E. (2002) Identification of a Novel Family of Presenilin Homologues. Hum Mol Genet. 11, 1037-1044.
3. Grigorenko, A. P., Moliaka, Y. K., Korovaitseva, G. I., and Rogaev, E. I. (2002) Novel Class of Polytopic Proteins with Domains Associated with Putative Protease Activity. Biochemistry (Mosc). 67, 826-835.
4. Martoglio, B., and Golde, T. E. (2003) Intramembrane-Cleaving Aspartic Proteases and Disease: Presenilins, Signal Peptide Peptidase and their Homologs. Hum Mol Genet. 12 Spec No 2, R201-6.
5. Friedmann, E., Hauben, E., Maylandt, K., Schleeger, S., Vreugde, S., Lichtenthaler, S. F., Kuhn, P. H., Stauffer, D., Rovelli, G., and Martoglio, B. (2006) SPPL2a and SPPL2b Promote Intramembrane Proteolysis of TNFalpha in Activated Dendritic Cells to Trigger IL-12 Production. Nat Cell Biol. 8, 843-848.
6. Martin, L., Fluhrer, R., Reiss, K., Kremmer, E., Saftig, P., and Haass, C. (2008) Regulated Intramembrane Proteolysis of Bri2 (Itm2b) by ADAM10 and SPPL2a/SPPL2b. J Biol Chem. 283, 1644-1652.
7. Kirkin, V., Cahuzac, N., Guardiola-Serrano, F., Huault, S., Luckerath, K., Friedmann, E., Novac, N., Wels, W. S., Martoglio, B., Hueber, A. O., and Zornig, M. (2007) The Fas Ligand Intracellular Domain is Released by ADAM10 and SPPL2a Cleavage in T-Cells. Cell Death Differ. 14, 1678-1687.
8. Schneppenheim, J., Dressel, R., Huttl, S., Lullmann-Rauch, R., Engelke, M., Dittmann, K., Wienands, J., Eskelinen, E. L., Hermans-Borgmeyer, I., Fluhrer, R., Saftig, P., and Schroder, B. (2013) The Intramembrane Protease SPPL2a Promotes B Cell Development and Controls Endosomal Traffic by Cleavage of the Invariant Chain. J Exp Med. 210, 41-58.
9. Bergmann, H., Yabas, M., Short, A., Miosge, L., Barthel, N., Teh, C. E., Roots, C. M., Bull, K. R., Jeelall, Y., Horikawa, K., Whittle, B., Balakishnan, B., Sjollema, G., Bertram, E. M., Mackay, F., Rimmer, A. J., Cornall, R. J., Field, M. A., Andrews, T. D., Goodnow, C. C., and Enders, A. (2013) B Cell Survival, Surface BCR and BAFFR Expression, CD74 Metabolism, and CD8- Dendritic Cells Require the Intramembrane Endopeptidase SPPL2A. J Exp Med. 210, 31-40.
10. Beisner, D. R., Langerak, P., Parker, A. E., Dahlberg, C., Otero, F. J., Sutton, S. E., Poirot, L., Barnes, W., Young, M. A., Niessen, S., Wiltshire, T., Bodendorf, U., Martoglio, B., Cravatt, B., and Cooke, M. P. (2013) The Intramembrane Protease Sppl2a is Required for B Cell and DC Development and Survival Via Cleavage of the Invariant Chain. J Exp Med. 210, 23-30.
11. Huttl, S., Klasener, K., Schweizer, M., Schneppenheim, J., Oberg, H. H., Kabelitz, D., Reth, M., Saftig, P., and Schroder, B. (2015) Processing of CD74 by the Intramembrane Protease SPPL2a is Critical for B Cell Receptor Signaling in Transitional B Cells. J Immunol. 195, 1548-1563.
12. Schneppenheim, J., Huttl, S., Kruchen, A., Fluhrer, R., Muller, I., Saftig, P., Schneppenheim, R., Martin, C. L., and Schroder, B. (2014) Signal-Peptide-Peptidase-Like 2a is Required for CD74 Intramembrane Proteolysis in Human B Cells. Biochem Biophys Res Commun. 451, 48-53.
13. Oliveira, C. C., Querido, B., Sluijter, M., de Groot, A. F., van der Zee, R., Rabelink, M. J., Hoeben, R. C., Ossendorp, F., van der Burg, S. H., and van Hall, T. (2013) New Role of Signal Peptide Peptidase to Liberate C-Terminal Peptides for MHC Class I Presentation. J Immunol. 191, 4020-4028.
14. Brady, O. A., Zhou, X., and Hu, F. (2014) Regulated Intramembrane Proteolysis of the Frontotemporal Lobar Degeneration Risk Factor, TMEM106B, by Signal Peptide Peptidase-Like 2a (SPPL2a). J Biol Chem. 289, 19670-19680.
15. Fleck, D., Voss, M., Brankatschk, B., Giudici, C., Hampel, H., Schwenk, B., Edbauer, D., Fukumori, A., Steiner, H., Kremmer, E., Haug-Kroper, M., Rossner, M. J., Fluhrer, R., Willem, M., and Haass, C. (2016) Proteolytic Processing of Neuregulin 1 Type III by Three Intramembrane-Cleaving Proteases. J Biol Chem. 291, 318-333.
|Science Writers||Anne Murray|
|Authors||Jin Huk Choi, James Butler, Bruce Beutler|
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