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|Coordinate||30,869,883 bp (GRCm38)|
|Base Change||A ⇒ G (forward strand)|
|Gene Name||CD22 antigen|
|Chromosomal Location||30,865,402-30,880,342 bp (-)|
|MGI Phenotype||Homozygous null mice have reduced mature B cell numbers with altered proliferation kinetics and reduced antibody production to T cell independent antigens.|
|Amino Acid Change||Serine changed to Proline|
|Institutional Source||Beutler Lab|
|Gene Model||predicted gene model for protein(s): [ENSMUSP00000019248]|
AA Change: S603P
|Predicted Effect||probably damaging
PolyPhen 2 Score 1.000 (Sensitivity: 1.80; Specificity: 1.00)
|Phenotypic Category||decrease in B cells, decrease in B2 cells, decrease in IgD MFI in B cells, increase in B1a cells, increase in B1b cells, post-MCMV decrease in B cells, post-MCMV decrease in IgD+ B cells, post-MCMV decrease in IgM+ B cells|
|Alleles Listed at MGI|
|Mode of Inheritance||Autosomal Recessive|
|Last Updated||05/12/2017 3:00 PM by Anne Murray|
|Record Created||11/01/2014 10:35 PM by Ming Zeng|
The crullers phenotype was identified among G3 mice of the pedigree R1245, some of which showed an increase in the frequency of B1a (Figure 1) and B1b cells (Figure 2), a decreased frequency of B2 cells (Figure 3), a decreased frequency of effector memory CD4+ T cells in CD4+ T cells (Figure 4), an increased frequency of central memory CD4+ T cells (Figure 5), and a decrease in IgD mean fluorescence intensity (Figure 6), all in the peripheral blood.
|Nature of Mutation|
Whole exome HiSeq sequencing of the G1 grandsire identified 39 mutations. All of the above anomalies were linked by continuous variable mapping to a mutation in Cd22: a T to C transition at base pair 30,869,883 (v38) on chromosome 7, or base pair 10,460 in the GenBank genomic region NC_000073. The strongest association was found with an additive model of linkage to the normalized frequency of peripheral B2 cells, wherein 8 variant homozygotes and 9 heterozygous mice departed phenotypically from 5 homozygous reference mice with a P value of 1.727 x 10-8 (Figure 7). A substantial semidominant effect was observed in most of the assays but the mutation is preponderantly recessive; in the B1b assay, a purely dominant effect observed. The mutation corresponds to residue 2,045 in the mRNA sequence NM_009845 within exon 8 of 14 total exons or residue 2,170 in the mRNA sequence NM_001043317 in exon 10 of 16 total exons.
Genomic numbering corresponds to NC_000073. The mutated nucleotide is indicated in red. The mutation results in a serine (S) to proline (P) substitution at position 603 (S603P) in both CD22 isoforms, and is strongly predicted by Polyphen-2 to cause loss of function (score = 1.00).
CD22 belongs to the Siglec (sialic acid-binding) family of adhesion molecules (1;2) (Figure 8). Siglecs are members of the immunoglobulin (Ig) superfamily, which specifically recognize sialic acids attached to the terminal regions of cell-surface glycoconjugates. CD22 is one of two Siglecs expressed by B cells (the other being Siglec-G), and was originally identified as a B cell-associated adhesion protein that functions in the regulation of B cell activation [reviewed in (3;4)]. CD22 associates with a number of BCR signaling molecules including the BCR complex itself. Upon cross-linking of the BCR by antigen, associated CD22 is rapidly phosphorylated by Lyn (5-7). The subsequent association of SHP1 with CD22 leads to the dephosphorylation of a number of BCR signaling components that dampens the BCR signal and Ca2+ mobilization such as Vav-1, CD19 and BLNK (8-10).
Siglec proteins are type 1 transmembrane proteins with a sialic acid-binding N-terminal Ig-like V-type domain, variable numbers of Ig-like C2-type domains, a transmembrane region, and a cytoplasmic tail. CD22 contains seven immunoglobulin domains in its extracellular region at amino acids 31-147, 156-254, 269-337, 365-424,448-523, 541-599, and 628-687 (1). The crullers mutation resides in the region between the sixth and seventh immunoglobulin domains.
See the record well for more information about Cd22.
In response to BCR stimulation, CD22-deficient B cells predominantly undergo apoptosis (11). Although CD22 appears to be dispensable for the differentiation of B cells to mature follicular cells, CD22-deficient B cells express less surface IgM, which may be a consequence of a faster and more complete maturation process. In addition, CD22-deficient mice have severely reduced numbers of marginal zone (MZ) B cells, and increased numbers of B-1 peritoneal cells was observed in two of the four knockout strains (12-15). The loss of MZ B cells and increased B-1 cell numbers in these mice may be due to altered BCR signaling during development as maturation into the three mature B cell subsets is driven in part by differences in BCR signal strength, and a strong BCR signal disrupts MZ B development and promotes B-1 differentiation [reviewed by (16;17)]. Due to the lack of MZ B cells, these animals display impaired immune responses to T-independent antigens (12;15;18), while T-dependent immune responses remain intact and subsequent germinal center formation occurs normally (11).
Mice carrying the crullers allele share several phenotypes with the CD22 knockout mice including defects in peripheral B cell maturation that are likely caused by reduced MZ B cell numbers. A defect in immune responses to T-dependent or T-independent antigens was not observed in the crullers mice indicating that some residual CD22 function may be found in the crullers mice.
crullers(F):5'- GGATTGGCATCACTCTCACAGGAC -3'
crullers(R):5'- CGTGAAGGTACTGAAGGTAAGCCC -3'
crullers_seq(F):5'- AGGACAAGGTGGCCTTCTTC -3'
crullers_seq(R):5'- TGAAGGTAAGCCCCGCATC -3'
Crullers genotyping is performed by amplifying the region containing the mutation using PCR, followed by sequencing of the amplified region to detect the single nucleotide transition.
Crullers (F): 5’- GGATTGGCATCACTCTCACAGGAC-3’
Crullers (R): 5’- CGTGAAGGTACTGAAGGTAAGCCC-3’
Crullers (F): 5’- AGGACAAGGTGGCCTTCTTC-3’
Crullers (R): 5’- TGAAGGTAAGCCCCGCATC-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 ∞
The following sequence of 427 nucleotides is amplified (Chr.7: 30869680-30870106, GRCm38; NC_000073):
ggattggcat cactctcaca ggacaaggtg gccttcttcc cctccatcac atggtcccca
gggctgatgg acacacgcag cctccgagga gcatctgtaa aggagacccc gagtcaggcc
ggggcagcgg gtcacctcat catcttctca tttaggcccc agctccagcc actcacacag
cacttggagg ttccaggcct gtgacaaggt ctctccgatg gagttgttga ccatgcagtt
ataatttcca gaatcttctg gggagacgga gccgaagctc aggtacctcc cttcctgcac
gagactccca ttcttcttcc agaagaagcg gacctctgcc gggttgctct ctgcgaagtc
gcattggagg aggacacgct gcccagcgcg gatctctgat gcggggctta ccttcagtac
Primer binding sites are underlined and the sequencing primer is highlighted; the mutated nucleotide (A) is shown in red text (Chr. + strand, T>C; sense strand, A>G).
1. Torres, R. M., Law, C. L., Santos-Argumedo, L., Kirkham, P. A., Grabstein, K., Parkhouse, R. M., and Clark, E. A. (1992) Identification and Characterization of the Murine Homologue of CD22, a B Lymphocyte-Restricted Adhesion Molecule. J Immunol. 149, 2641-2649.
2. Wilson, G. L., Fox, C. H., Fauci, A. S., and Kehrl, J. H. (1991) CDNA Cloning of the B Cell Membrane Protein CD22: A Mediator of B-B Cell Interactions. J Exp Med. 173, 137-146.
4. Nitschke, L. (2009) CD22 and Siglec-G: B-Cell Inhibitory Receptors with Distinct Functions. Immunol Rev. 230, 128-143.
5. Leprince, C., Draves, K. E., Geahlen, R. L., Ledbetter, J. A., and Clark, E. A. (1993) CD22 Associates with the Human Surface IgM-B-Cell Antigen Receptor Complex. Proc Natl Acad Sci U S A. 90, 3236-3240.
6. Smith, K. G., Tarlinton, D. M., Doody, G. M., Hibbs, M. L., and Fearon, D. T. (1998) Inhibition of the B Cell by CD22: A Requirement for Lyn. J Exp Med. 187, 807-811.
7. Schulte, R. J., Campbell, M. A., Fischer, W. H., and Sefton, B. M. (1992) Tyrosine Phosphorylation of CD22 during B Cell Activation. Science. 258, 1001-1004.
8. Gerlach, J., Ghosh, S., Jumaa, H., Reth, M., Wienands, J., Chan, A. C., and Nitschke, L. (2003) B Cell Defects in SLP65/BLNK-Deficient Mice can be Partially Corrected by the Absence of CD22, an Inhibitory Coreceptor for BCR Signaling. Eur J Immunol. 33, 3418-3426.
9. Sato, S., Jansen, P. J., and Tedder, T. F. (1997) CD19 and CD22 Expression Reciprocally Regulates Tyrosine Phosphorylation of Vav Protein during B Lymphocyte Signaling. Proc Natl Acad Sci U S A. 94, 13158-13162.
10. Fujimoto, M., Bradney, A. P., Poe, J. C., Steeber, D. A., and Tedder, T. F. (1999) Modulation of B Lymphocyte Antigen Receptor Signal Transduction by a CD19/CD22 Regulatory Loop. Immunity. 11, 191-200.
11. Poe, J. C., Fujimoto, Y., Hasegawa, M., Haas, K. M., Miller, A. S., Sanford, I. G., Bock, C. B., Fujimoto, M., and Tedder, T. F. (2004) CD22 Regulates B Lymphocyte Function in Vivo through both Ligand-Dependent and Ligand-Independent Mechanisms. Nat Immunol. 5, 1078-1087.
12. Otipoby, K. L., Andersson, K. B., Draves, K. E., Klaus, S. J., Farr, A. G., Kerner, J. D., Perlmutter, R. M., Law, C. L., and Clark, E. A. (1996) CD22 Regulates Thymus-Independent Responses and the Lifespan of B Cells. Nature. 384, 634-637.
13. Sato, S., Miller, A. S., Inaoki, M., Bock, C. B., Jansen, P. J., Tang, M. L., and Tedder, T. F. (1996) CD22 is both a Positive and Negative Regulator of B Lymphocyte Antigen Receptor Signal Transduction: Altered Signaling in CD22-Deficient Mice. Immunity. 5, 551-562.
14. O'Keefe, T. L., Williams, G. T., Davies, S. L., and Neuberger, M. S. (1996) Hyperresponsive B Cells in CD22-Deficient Mice. Science. 274, 798-801.
15. Nitschke, L., Carsetti, R., Ocker, B., Kohler, G., and Lamers, M. C. (1997) CD22 is a Negative Regulator of B-Cell Receptor Signalling. Curr Biol. 7, 133-143.
16. Niiro, H., and Clark, E. A. (2002) Regulation of B-Cell Fate by Antigen-Receptor Signals. Nat Rev Immunol. 2, 945-956.
17. Pillai, S., Cariappa, A., and Moran, S. T. (2005) Marginal Zone B Cells. Annu Rev Immunol. 23, 161-196.
|Science Writers||Anne Murray|
|Authors||Ming Zeng, Bruce Beutler|
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