* 604491
CAS-BR-M MURINE ECOTROPIC RETROVIRAL TRANSFORMING SEQUENCE B; CBLB
HGNC Approved Gene Symbol: CBLB
Cytogenetic location: 3q13.11 Genomic coordinates (GRCh38) : 3:105,655,461-105,869,449 (from NCBI)
Gene-Phenotype Relationships
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 3q13.11 | Autoimmune disease, multisystem, infantile-onset, 3 | 620430 | Autosomal recessive | 3 |
TEXT
Description
CBLB is a key regulator of peripheral immune tolerance by limiting T-cell activation and expansion through its E3 ubiquitin ligase activity (Sturner et al., 2014).
Cloning and Expression
The oncogene CBL (165360) is expressed in a range of hematopoietic cells and maps close to genes of other immune cell markers on chromosome 11q23.3. By screening a breast cancer cDNA library, Keane et al. (1995) identified a 2.2-kb clone for a single-copy gene, termed CBLB, that has high homology to CBL. Northern blot analysis revealed expression of the gene in normal and malignant breast epithelial cell lines as a major 4- to 5-kb transcript and a less prominent 6- to 8-kb transcript. Expression was also observed in normal adult lung, kidney, spleen, and testis, as well as fetal brain and liver and hematopoietic cell lines, but not in adult brain, liver, pancreas, salivary gland, or skeletal muscle. CBLB cDNA encodes a predicted 982-amino acid protein. Like CBL, CBLB contains putative nuclear localization signal, zinc finger, leucine zipper, and proline-rich domains. RT-PCR analysis indicated that there are leucine zipper-negative alternatively spliced forms of CBLB detectable in breast cancer cell lines. CBLB associates with FYN (137025), FGR (164940), and PLCG1 (172420) but not with the SH3 proteins NCK1 (600508), SPTA1 (182860), or EPS8 (600206).
Gene Structure
Nau and Lipkowitz (2003) determined that the CBLB gene contains 21 exons, including 3 alternate first exons in the 5-prime UTR, and spans more than 206 kb.
Mapping
Keane et al. (1995) mapped the CBLB gene to the mid-portion of chromosome 3q by somatic cell hybrid analysis and FISH. By genomic sequence analysis, Nau and Lipkowitz (2003) mapped the CBLB gene to chromosome 3q11-q13.1.
Gross (2015) mapped the CBLB gene to chromosome 3q13.11 based on an alignment of the CBLB sequence (GenBank BC032851) with the genomic sequence (GRCh38).
Gene Function
Stimulation of the T-cell antigen receptor (TCR) alone may result in anergy or T-cell deletion, whereas co-stimulation of the TCR and CD28 results in T-cell activation. Chiang et al. (2000) and Bachmaier et al. (2000) showed that the requirement of CD28 engagement for IL2 (147680) production in vitro as well as anti-NP IgG1 and IgG2b in vivo is diminished in the absence of CBLB. Chiang et al. (2000) found that phosphorylation mediated by CD3Z (186780), ZAP70 (176947), and LCK (153390) tyrosine kinases or by MAP kinases is not impaired by lack of CBLB. In addition to enhanced VAV1 (164875) phosphorylation upon anti-CD3E or anti-CD3E/anti-CD28 stimulation, Chiang et al. (2000) detected much higher VAV1/GEF 601855 activity in CBLB-deficient cells than in wildtype cells. CBLB-deficient mice were also much more susceptible to experimental autoimmune encephalomyelitis, a model for multiple sclerosis (126200), after immunization with myelin basic protein (159430).
The autoimmune disease type 1 diabetes mellitus (T1D; 222100), also known as insulin-dependent diabetes mellitus (IDDM), has a multifactorial etiology. The major histocompatibility complex (MHC) has been identified as a major susceptibility locus in the disease and its animal models. The Komeda diabetes-prone (KDP) rat is a spontaneous animal model of human type 1 diabetes (Komeda et al., 1998) in which the major susceptibility locus Iddm/kdp1 accounts, in combination with MHC, for most of the genetic predisposition to diabetes. Yokoi et al. (2002) reported positional cloning of Iddm/kdp1 and identification of a nonsense mutation in Cblb. Lymphocytes of the KDP rat infiltrate pancreatic islets and several tissues including thyroid gland and kidney, indicating autoimmunity. Similar findings in Cblb-deficient mice are caused by enhanced T-cell activation. Transgenic complementation with wildtype Cblb significantly suppressed development of the KDP phenotype. Thus, Cblb functions as a negative regulator of autoimmunity and Cblb is a major susceptibility gene for type 1 diabetes in the rat. Yokoi et al. (2002) concluded that impairment of the Cblb signaling pathway may contribute to human autoimmune diseases, including type 1 diabetes.
Bachmaier et al. (2007) showed that, in addition to its role in the prevention of chronic inflammation and autoimmunity, CBLB also has an unexpected function in acute lung inflammation. In a mouse model of polymicrobial sepsis in which acute lung inflammation depends on the LPS receptor (TLR4; 603030), the loss of Cblb expression accentuated acute lung inflammation and reduced survival. Loss of Cblb significantly increased sepsis-induced release of inflammatory cytokines and chemokines. CBLB controls the association between TLR4 and the intracellular adaptor MyD88 (602170). Expression of wildtype Cblb, but not expression of a Cblb mutant that lacks E3 ubiquitin ligase function, prevented the activity of a reporter gene for the transcription factor nuclear factor kappa-B (NFKB; see 164011) in monocytes that had been challenged with LPS. The downregulation of Tlr4 expression on the cell surface of neutrophils was impaired in the absence of Cblb. Bachmaier et al. (2007) concluded that CBLB regulates the TLR4-mediated acute inflammatory response that is induced by sepsis.
Paolino et al. (2014) demonstrated that genetic deletion of the E3 ubiquitin ligase CBLB or targeted inactivation of its E3 ligase activity licenses natural killer (NK) cells to spontaneously reject metastatic tumors. The TAM tyrosine kinase receptors TYRO3 (600341), AXL (109135), and MERTK (604705) were identified as ubiquitylation substrates for CBLB. Treatment of wildtype NK cells with a small molecule TAM kinase inhibitor conferred therapeutic potential, efficiently enhancing antimetastatic NK cell activity in vivo. Oral or intraperitoneal administration using this TAM inhibitor markedly reduced murine mammary cancer and melanoma metastases dependent on NK cells. Paolino et al. (2014) further reported that the anticoagulant warfarin exerts antimetastatic activity in mice via Cblb/TAM receptors in NK cells, providing a molecular explanation for the effect of warfarin to reduce tumor metastases in rodent models. Paolino et al. (2014) concluded that this novel TAM/CBLB inhibitory pathway shows that it might be possible to develop a 'pill' that awakens the innate immune system to kill cancer metastases.
Molecular Genetics
In 3 unrelated patients with infantile-onset multisystem autoimmune disease-3 (ADMIO3; 620430), Janssen et al. (2022) identified homozygous mutations in the CBLB gene (604491.0001-604491.0003). There were 2 missense variants and 1 nonsense variant. The mutations, which were found by exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the families. None were present in the gnomAD database. CD4+ T cells derived from 2 of the patients showed hyperproliferation in response to CD3 and CD3 plus CD28 stimulation. Studies of mice carrying 1 of the mutations (H285L; 604491.0001) showed similar immune dysregulation, with hyperproliferation of CD4+ T cells and activation of B cells after stimulation (see ANIMAL MODEL). Janssen et al. (2022) concluded that the combination of CD4+ T cell hyperproliferation, resistance to Treg suppression, and possibly increased BCR signaling may contribute to the development of autoimmunity in CBLB-deficient patients.
Associations Pending Confirmation
Sturner et al. (2014) noted that risk alleles for multiple sclerosis (MS; 126200) are located near the CBLB gene. Using RT-PCR, they found reduced CBLB expression in CD4-positive T cells from relapsing-remitting MS patients compared with healthy controls and MS patients in remission. The MS risk allele (T) of the SNP rs12487066, which is located over 320 kb upstream of the CBLB coding region, was associated with reduced CBLB expression levels, and it altered the effects of type I interferons on CD4-positive T-cell proliferation. The risk allele of rs12487066 mediated increased binding of CEBPB (189965) to CBLB and reduced CBLB expression in CD4-positive T cells. Sturner et al. (2014) proposed that rs12487066 has a role in the interactions of a genetic risk factor and interferon function during viral infections in MS.
Animal Model
Bachmaier et al. (2000) generated mice deficient in CBLB by targeted disruption. At 6 months of age, these mice, which were maintained under specific pathogen-free conditions, exhibited a huge mass in submandibular salivary glands which resulted from accumulations of T and B cells and lymphoid neoorganogenesis. Mononuclear cells also accumulated in and damaged multiple organs and tissues, although the enlargement was only slight in spleen and lymph nodes. In CBLB +/- mice, the authors detected minor infiltration in only the submandibular salivary glands and kidneys. Measurement of a number of in vitro parameters demonstrated hyperproliferation of T and B cells as well as hyperproduction of IL2 (147680) but not of IFNG (147570) or TNFA (191160).
Naramura et al. (2002) generated double-knockout (dKO) mice lacking both Cbl and Cblb. They found that dKO T cells were hyperresponsive to anti-CD3 stimulation, although the major T-cell receptor (TCR) signaling pathways were not enhanced. The dKO T cells failed to modulate surface TCR after ligand engagement, resulting in sustained TCR signaling. Naramura et al. (2002) proposed that the CBL family proteins negatively regulate T-cell activation by promoting clearance of engaged TCR from the cell surface, which appears to be necessary for the termination of TCR signals.
Tan et al. (2006) found that Cblb-null mice demonstrated higher long-term memory retention compared to wildtype mice. Immunohistochemical analysis detected Cblb in the synaptic regions of hippocampal regions CA1, CA3, and the dentate gyrus. Electrophysiologic studies suggested that the Cblb-null mice had enhanced glutamatergic presynaptic short-term plasticity compared to wildtype mice.
Janssen et al. (2022) found that mice homozygous for a missense H257L mutation in the CBLB gene (which corresponds to the human H285L mutation, 604491.0001) generated by CRISPR/Cas9 gene editing showed immune dysregulation. T cells from these mice had an approximately 50% decrease in mutant protein expression. CD4+ T cells demonstrated hyperproliferation and increased IL2 secretion after anti-CD3 stimulation, although this was not associated with increased intracellular signaling. Treg cells were increased in the spleen, but mutant CD4+ T cells were resistant to suppression. B cells and bone marrow-derived mast cells also showed increased proliferation and hyperactivation when stimulated. Importantly, mutant mice did not develop autoimmune disease under pathogen-free conditions, indicating that environmental factors, including infection, may be necessary for triggering an autoimmune response.
ALLELIC VARIANTS 3 Selected Examples):
.0001 AUTOIMMUNE DISEASE, MULTISYSTEM, INFANTILE-ONSET, 3
SNP: rs2546956921, ClinVar: RCV003237385
In a 16-year-old girl (P1), born of consanguineous Saudi parents, with infantile-onset multisystem autoimmune disease-3 (ADMIO3; 620430), Janssen et al. (2022) identified a homozygous c.854A-T transversion (c.854A-T, NM_001321786.1) in the CBLB gene, resulting in a his285-to-leu (H285L) substitution in the SH2 binding subdomain. The mutation, which was found by exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the family and was not present in the gnomAD database. Immunoblot analysis of patient-derived B cells showed an approximately 50% reduction in levels of the mutant protein compared to controls. Patient CD4+ T cells showed hyperproliferation in response to anti-CD3 and anti-CD3 plus anti-CD28 compared to controls. In addition, the patient had a decreased percentage of T-regulatory cells (Tregs), and the CD4+ T-cell proliferation was resistant to suppression by Tregs from healthy controls.
.0002 AUTOIMMUNE DISEASE, MULTISYSTEM, INFANTILE-ONSET, 3
SNP: rs535219619, gnomAD: rs535219619, ClinVar: RCV003237386
In an 11-year-old boy, born of unrelated Saudi parents, with infantile-onset multisystem autoimmune disease-3 (ADMIO3; 620430), Janssen et al. (2022) identified a homozygous c.1486C-T transition (c.1486C-T, NM_001321786.1) in the CBLB gene, resulting in an arg496-to-ter (R496X) substitution. The mutation, which was found by exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the family and was not present in the gnomAD database. An antibody against the N terminus of CBLB failed to detect a truncated product in patient cells. Patient-derived CD4+ T cells showed hyperproliferation when stimulated with anti-CD3 and anti-CD3 plus anti-CD28.
.0003 AUTOIMMUNE DISEASE, MULTISYSTEM, INFANTILE-ONSET, 3
SNP: rs2152826353, ClinVar: RCV003237387
In a 4-year-old boy (P3), born of consanguineous Omani parents, with infantile-onset multisystem autoimmune disease-3 (ADMIO3; 620430) Janssen et al. (2022) identified a homozygous c.1392C-G transversion (c.1392C-G, NM_001321786.1) in the CBLB gene, resulting in a cys464-to-trp (C464W) substitution. The mutation, which was found by exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in the family and was not present in the gnomAD database. Immunoblot analysis of patient cells showed intact CBLB protein expression; additional patient samples were not available for functional studies.
REFERENCES
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Bachmaier, K., Krawczyk, C., Kozieradzki, I., Kong, Y.-Y., Sasaki, T., Oliveira-dos-Santos, A., Mariathasan, S., Bouchard, D., Wakeham, A., Itie, A., Le, J., Ohashi, P. S., Sarosi, I., Nishina, H., Lipkowitz, S., Penninger, J. M. Negative regulation of lymphocyte activation and autoimmunity by the molecular adaptor Cbl-b. Nature 403: 211-216, 2000. [PubMed: 10646608] [Full Text: https://doi.org/10.1038/35003228]
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Bachmaier, K., Toya, S., Gao, X., Triantafillou, T., Garrean, S., Park, G. Y., Frey, R. S., Vogel, S., Minshall, R., Christman, J. W., Tiruppathi, C., Malik, A. B. E3 ubiquitin ligase Cblb regulates the acute inflammatory response underlying lung injury. Nature Med. 13: 920-926, 2007. [PubMed: 17618294] [Full Text: https://doi.org/10.1038/nm1607]
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Chiang, Y. J., Kole, H. K., Brown, K., Naramura, M., Fukuhara, S., Hu, R.-J., Jang, I. K., Gutkind, J. S., Shevach, E., Gu, H. Cbl-b regulates the CD28 dependence of T-cell activation. Nature 403: 216-220, 2000. [PubMed: 10646609] [Full Text: https://doi.org/10.1038/35003235]
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Gross, M. B. Personal Communication. Baltimore, Md. 8/31/2015.
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Janssen, E., Peters, Z., Alosaimi, M. F., Smith, E., Milin, E., Stafstrom, K., Wallace, J. G., Platt, C. D., Chou, J., El Ansari, Y. S., Al Farsi, T., Ameziane, N., and 9 others. Immune dysregulation caused by homozygous mutations in CBLB. J. Clin. Invest. 132: e154487, 2022. [PubMed: 36006710] [Full Text: https://doi.org/10.1172/JCI154487]
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Keane, M. M., Rivero-Lezcano, O. M., Mitchell, J. A., Robbins, K. C., Lipkowitz, S. Cloning and characterization of cbl-b: a SH3 binding protein with homology to the c-cbl proto-oncogene. Oncogene 10: 2367-2377, 1995. [PubMed: 7784085]
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Komeda, K., Noda, M., Terao, K., Kuzuya, N., Kanazawa, M., Kanazawa, Y. Establishment of two substrains, diabetes-prone and nondiabetic, from Long-Evans Tokushima Lean (LETL) rats. Endocr. J. 45: 737-744, 1998. [PubMed: 10395228] [Full Text: https://doi.org/10.1507/endocrj.45.737]
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Naramura, M., Jang, I.-K., Kole, H., Huang, F., Haines, D., Gu, H. c-Cbl and Cbl-b regulate T cell responsiveness by promoting ligand-induced TCR down-modulation. Nature Immun. 3: 1192-1199, 2002. [PubMed: 12415267] [Full Text: https://doi.org/10.1038/ni855]
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Sturner, K. H., Borgmeyer, U., Schulze, C., Pless, O., Martin, R. A multiple sclerosis-associated variant of CBLB links genetic risk with type I IFN function. J. Immun. 193: 4439-4447, 2014. [PubMed: 25261476] [Full Text: https://doi.org/10.4049/jimmunol.1303077]
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Tan, D. P., Liu, Q.-Y., Koshiya, N., Gu, H., Alkon, D. Enhancement of long-term memory retention and short-term synaptic plasticity in cbl-b null mice. Proc. Nat. Acad. Sci. 103: 5125-5130, 2006. [PubMed: 16549761] [Full Text: https://doi.org/10.1073/pnas.0601043103]
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Yokoi, N., Komeda, K., Wang, H.-Y., Yano, H., Kitada, K., Saitoh, Y., Seino, Y., Yasuda, K., Serikawa, T., Seino, S. Cblb is a major susceptibility gene for rat type 1 diabetes mellitus. Nature Genet. 31: 391-394, 2002. [PubMed: 12118252] [Full Text: https://doi.org/10.1038/ng927]
Matthew B. Gross - updated : 08/31/2015
Paul J. Converse - updated : 7/16/2015
Ada Hamosh - updated : 4/14/2014
Ada Hamosh - updated : 3/26/2008
Cassandra L. Kniffin - updated : 5/18/2006
Patricia A. Hartz - updated : 2/9/2004
Paul J. Converse - updated : 1/15/2004
Victor A. McKusick - updated : 7/17/2002
ckniffin : 06/27/2023
carol : 11/19/2020
mgross : 08/31/2015
mgross : 7/22/2015
mcolton : 7/16/2015
alopez : 4/14/2014
terry : 1/27/2012
alopez : 3/27/2008
terry : 3/26/2008
wwang : 6/14/2006
ckniffin : 5/18/2006
mgross : 2/9/2004
mgross : 1/15/2004
mgross : 1/15/2004
alopez : 8/1/2002
alopez : 7/22/2002
alopez : 7/22/2002
terry : 7/17/2002
carol : 2/4/2000