RESUMO
Signal transducer and activator of transcription 3 (STAT3) is a central regulator of immune homeostasis. STAT3 levels are strictly controlled, and STAT3 impairment contributes to several diseases including the monogenic autosomal-dominant hyper-immunoglobulin E (IgE) syndrome (AD-HIES). We investigated patients of four consanguineous families with an autosomal-recessive disorder resembling the phenotype of AD-HIES, with symptoms of immunodeficiency, recurrent infections, skeletal abnormalities, and elevated IgE. Patients presented with reduced STAT3 expression and diminished T helper 17 cell numbers, in absence of STAT3 mutations. We identified two distinct homozygous nonsense mutations in ZNF341, which encodes a zinc finger transcription factor. Wild-type ZNF341 bound to and activated the STAT3 promoter, whereas the mutant variants showed impaired transcriptional activation, partly due to nuclear translocation failure. In summary, nonsense mutations in ZNF341 account for the STAT3-like phenotype in four autosomal-recessive kindreds. Thus, ZNF341 is a previously unrecognized regulator of immune homeostasis.
Assuntos
Imunocompetência/genética , Síndrome de Job/genética , Fator de Transcrição STAT3/genética , Células Th17/imunologia , Fatores de Transcrição/genética , Adolescente , Adulto , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Núcleo Celular/metabolismo , Criança , Códon sem Sentido , Consanguinidade , Éxons/genética , Feminino , Genes Recessivos/genética , Genes Recessivos/imunologia , Humanos , Imunoglobulina E/sangue , Imunoglobulina E/imunologia , Lactente , Síndrome de Job/sangue , Síndrome de Job/imunologia , Masculino , Linhagem , Regiões Promotoras Genéticas/genética , Fator de Transcrição STAT3/imunologia , Células Th17/metabolismo , Fatores de Transcrição/imunologia , Fatores de Transcrição/metabolismo , Adulto Jovem , Dedos de Zinco/genéticaRESUMO
BACKGROUND: Primary antibody deficiencies (PADs) are the most frequent primary immunodeficiencies in human subjects. The genetic causes of PADs are largely unknown. Sec61 translocon alpha 1 subunit (SEC61A1) is the major subunit of the Sec61 complex, which is the main polypeptide-conducting channel in the endoplasmic reticulum membrane. SEC61A1 is a target gene of spliced X-box binding protein 1 and strongly induced during plasma cell (PC) differentiation. OBJECTIVE: We identified a novel genetic defect and studied its pathologic mechanism in 11 patients from 2 unrelated families with PADs. METHODS: Whole-exome and targeted sequencing were conducted to identify novel genetic mutations. Functional studies were carried out ex vivo in primary cells of patients and in vitro in different cell lines to assess the effect of SEC61A1 mutations on B-cell differentiation and survival. RESULTS: We investigated 2 families with patients with hypogammaglobulinemia, severe recurrent respiratory tract infections, and normal peripheral B- and T-cell subpopulations. On in vitro stimulation, B cells showed an intrinsic deficiency to develop into PCs. Genetic analysis and targeted sequencing identified novel heterozygous missense (c.254T>A, p.V85D) and nonsense (c.1325G>T, p.E381*) mutations in SEC61A1, segregating with the disease phenotype. SEC61A1-V85D was deficient in cotranslational protein translocation, and it disturbed the cellular calcium homeostasis in HeLa cells. Moreover, SEC61A1-V85D triggered the terminal unfolded protein response in multiple myeloma cell lines. CONCLUSION: We describe a monogenic defect leading to a specific PC deficiency in human subjects, expanding our knowledge about the pathogenesis of antibody deficiencies.
Assuntos
Síndromes de Imunodeficiência/genética , Mutação/genética , Plasmócitos/patologia , Canais de Translocação SEC/genética , Agamaglobulinemia/genética , Agamaglobulinemia/metabolismo , Agamaglobulinemia/patologia , Linfócitos B/metabolismo , Linfócitos B/patologia , Cálcio/metabolismo , Diferenciação Celular/genética , Linhagem Celular , Linhagem Celular Tumoral , Exoma/genética , Células HEK293 , Células HeLa , Heterozigoto , Humanos , Síndromes de Imunodeficiência/metabolismo , Plasmócitos/metabolismo , Transporte Proteico/genética , Infecções Respiratórias/genética , Infecções Respiratórias/metabolismo , Infecções Respiratórias/patologia , Linfócitos T/metabolismo , Linfócitos T/patologia , Resposta a Proteínas não Dobradas/genéticaRESUMO
Common variable immunodeficiency (CVID), characterized by recurrent infections, is the most prevalent symptomatic antibody deficiency. In â¼90% of CVID-affected individuals, no genetic cause of the disease has been identified. In a Dutch-Australian CVID-affected family, we identified a NFKB1 heterozygous splice-donor-site mutation (c.730+4A>G), causing in-frame skipping of exon 8. NFKB1 encodes the transcription-factor precursor p105, which is processed to p50 (canonical NF-κB pathway). The altered protein bearing an internal deletion (p.Asp191_Lys244delinsGlu; p105ΔEx8) is degraded, but is not processed to p50ΔEx8. Altered NF-κB1 proteins were also undetectable in a German CVID-affected family with a heterozygous in-frame exon 9 skipping mutation (c.835+2T>G) and in a CVID-affected family from New Zealand with a heterozygous frameshift mutation (c.465dupA) in exon 7. Given that residual p105 and p50translated from the non-mutated alleleswere normal, and altered p50 proteins were absent, we conclude that the CVID phenotype in these families is caused by NF-κB1 p50 haploinsufficiency.
