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Human PMS2 deficiency is associated with impaired immunoglobulin class switch recombination.

Péron S, Metin A, Gardès P, Alyanakian MA, Sheridan E, Kratz CP, Fischer A, Durandy A - J. Exp. Med. (2008)

Bottom Line: In some cases, CSR deficiencies can be associated with abnormal somatic hypermutation.Analysis of CSR deficiencies has helped reveal the key functions of CSR-triggering molecules, i.e., CD40L, CD40, and effector molecules such as activation-induced cytidine deaminase and uracil N-glycosylase.CSR was found partially defective in vivo and markedly impaired in vitro.

View Article: PubMed Central - PubMed

Affiliation: Institut National de Santé et de Recherche Médicale, U768, 75015 Paris, France.

ABSTRACT
Immunoglobulin (Ig) class switch recombination (CSR) deficiencies are rare primary immunodeficiencies characterized by the lack of switched isotype (IgG/IgA/IgE) production. In some cases, CSR deficiencies can be associated with abnormal somatic hypermutation. Analysis of CSR deficiencies has helped reveal the key functions of CSR-triggering molecules, i.e., CD40L, CD40, and effector molecules such as activation-induced cytidine deaminase and uracil N-glycosylase. We report a new form of B cell-intrinsic CSR deficiency found in three patients with deleterious, homozygous mutations in the gene encoding the PMS2 component of the mismatch repair machinery. CSR was found partially defective in vivo and markedly impaired in vitro. It is characterized by the defective occurrence of double-strand DNA breaks (DSBs) in switch regions and abnormal formation of switch junctions. This observation strongly suggests a role for PMS2 in CSR-induced DSB generation.

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PMS2 deficiency. (A) Mutations in the PMS2 gene. Mutations in PMS2 gene and predicted proteins. (B) PMS2 protein expression in patients' fibroblasts and EBV B cell lines by Western blot analysis. Antibody raised against the C terminus of PMS2 failed to detect PMS2 in P1 fibroblasts (n = 1), whereas an antibody raised against the N terminus revealed a truncated 46-kD protein (not found in control cells) in P1 fibroblasts (n = 3) and the EBV B cell line (n = 1). The antibody specific for the N terminus of PMS2 revealed no detectable protein in P2 EBV B cells (n = 3). MLH1 expression was found to be lower in P1 fibroblasts and in P1 and P2 EBV B cell lines (n = 3) compared with control cells. (C) Subcellular localization of PMS2. Primary fibroblasts from a control and P1 were labeled with anti–N-terminal PMS2 and anti-MLH1 antibodies, followed by secondary antibody (Alexa Fluor 488). PMS2 was predominantly observed in the cytoplasm in P1 fibroblasts, contrasting with a predominantly nuclear localization in control fibroblasts. No difference was observed in terms of the subcellular localization of MLH1, although MLH1 expression appeared to be slightly lower in P1 cells (n = 3). Bar, 20 μm.
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fig2: PMS2 deficiency. (A) Mutations in the PMS2 gene. Mutations in PMS2 gene and predicted proteins. (B) PMS2 protein expression in patients' fibroblasts and EBV B cell lines by Western blot analysis. Antibody raised against the C terminus of PMS2 failed to detect PMS2 in P1 fibroblasts (n = 1), whereas an antibody raised against the N terminus revealed a truncated 46-kD protein (not found in control cells) in P1 fibroblasts (n = 3) and the EBV B cell line (n = 1). The antibody specific for the N terminus of PMS2 revealed no detectable protein in P2 EBV B cells (n = 3). MLH1 expression was found to be lower in P1 fibroblasts and in P1 and P2 EBV B cell lines (n = 3) compared with control cells. (C) Subcellular localization of PMS2. Primary fibroblasts from a control and P1 were labeled with anti–N-terminal PMS2 and anti-MLH1 antibodies, followed by secondary antibody (Alexa Fluor 488). PMS2 was predominantly observed in the cytoplasm in P1 fibroblasts, contrasting with a predominantly nuclear localization in control fibroblasts. No difference was observed in terms of the subcellular localization of MLH1, although MLH1 expression appeared to be slightly lower in P1 cells (n = 3). Bar, 20 μm.

Mentions: The PMS2 deletion was predicted to lead to a truncated protein lacking the MLH1 dimerization domain, the endonuclease domain, the putative nuclear localization signal, and the nuclear export signal (Fig. 2 A) (15). As previously reported, a homozygous PMS2 nonsense mutation predicting a defect downstream from the endonuclease domain, at the very end of the domain of interaction with MLH1, was found in P2 (p.R802X) (16). P3 carried a homozygous frameshift mutation in PMS2, leading to a premature stop codon and the loss of exons 12–15 and most of exon 11 (p.N412DfsX6; Fig. 2 A) (17).


Human PMS2 deficiency is associated with impaired immunoglobulin class switch recombination.

Péron S, Metin A, Gardès P, Alyanakian MA, Sheridan E, Kratz CP, Fischer A, Durandy A - J. Exp. Med. (2008)

PMS2 deficiency. (A) Mutations in the PMS2 gene. Mutations in PMS2 gene and predicted proteins. (B) PMS2 protein expression in patients' fibroblasts and EBV B cell lines by Western blot analysis. Antibody raised against the C terminus of PMS2 failed to detect PMS2 in P1 fibroblasts (n = 1), whereas an antibody raised against the N terminus revealed a truncated 46-kD protein (not found in control cells) in P1 fibroblasts (n = 3) and the EBV B cell line (n = 1). The antibody specific for the N terminus of PMS2 revealed no detectable protein in P2 EBV B cells (n = 3). MLH1 expression was found to be lower in P1 fibroblasts and in P1 and P2 EBV B cell lines (n = 3) compared with control cells. (C) Subcellular localization of PMS2. Primary fibroblasts from a control and P1 were labeled with anti–N-terminal PMS2 and anti-MLH1 antibodies, followed by secondary antibody (Alexa Fluor 488). PMS2 was predominantly observed in the cytoplasm in P1 fibroblasts, contrasting with a predominantly nuclear localization in control fibroblasts. No difference was observed in terms of the subcellular localization of MLH1, although MLH1 expression appeared to be slightly lower in P1 cells (n = 3). Bar, 20 μm.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2571921&req=5

fig2: PMS2 deficiency. (A) Mutations in the PMS2 gene. Mutations in PMS2 gene and predicted proteins. (B) PMS2 protein expression in patients' fibroblasts and EBV B cell lines by Western blot analysis. Antibody raised against the C terminus of PMS2 failed to detect PMS2 in P1 fibroblasts (n = 1), whereas an antibody raised against the N terminus revealed a truncated 46-kD protein (not found in control cells) in P1 fibroblasts (n = 3) and the EBV B cell line (n = 1). The antibody specific for the N terminus of PMS2 revealed no detectable protein in P2 EBV B cells (n = 3). MLH1 expression was found to be lower in P1 fibroblasts and in P1 and P2 EBV B cell lines (n = 3) compared with control cells. (C) Subcellular localization of PMS2. Primary fibroblasts from a control and P1 were labeled with anti–N-terminal PMS2 and anti-MLH1 antibodies, followed by secondary antibody (Alexa Fluor 488). PMS2 was predominantly observed in the cytoplasm in P1 fibroblasts, contrasting with a predominantly nuclear localization in control fibroblasts. No difference was observed in terms of the subcellular localization of MLH1, although MLH1 expression appeared to be slightly lower in P1 cells (n = 3). Bar, 20 μm.
Mentions: The PMS2 deletion was predicted to lead to a truncated protein lacking the MLH1 dimerization domain, the endonuclease domain, the putative nuclear localization signal, and the nuclear export signal (Fig. 2 A) (15). As previously reported, a homozygous PMS2 nonsense mutation predicting a defect downstream from the endonuclease domain, at the very end of the domain of interaction with MLH1, was found in P2 (p.R802X) (16). P3 carried a homozygous frameshift mutation in PMS2, leading to a premature stop codon and the loss of exons 12–15 and most of exon 11 (p.N412DfsX6; Fig. 2 A) (17).

Bottom Line: In some cases, CSR deficiencies can be associated with abnormal somatic hypermutation.Analysis of CSR deficiencies has helped reveal the key functions of CSR-triggering molecules, i.e., CD40L, CD40, and effector molecules such as activation-induced cytidine deaminase and uracil N-glycosylase.CSR was found partially defective in vivo and markedly impaired in vitro.

View Article: PubMed Central - PubMed

Affiliation: Institut National de Santé et de Recherche Médicale, U768, 75015 Paris, France.

ABSTRACT
Immunoglobulin (Ig) class switch recombination (CSR) deficiencies are rare primary immunodeficiencies characterized by the lack of switched isotype (IgG/IgA/IgE) production. In some cases, CSR deficiencies can be associated with abnormal somatic hypermutation. Analysis of CSR deficiencies has helped reveal the key functions of CSR-triggering molecules, i.e., CD40L, CD40, and effector molecules such as activation-induced cytidine deaminase and uracil N-glycosylase. We report a new form of B cell-intrinsic CSR deficiency found in three patients with deleterious, homozygous mutations in the gene encoding the PMS2 component of the mismatch repair machinery. CSR was found partially defective in vivo and markedly impaired in vitro. It is characterized by the defective occurrence of double-strand DNA breaks (DSBs) in switch regions and abnormal formation of switch junctions. This observation strongly suggests a role for PMS2 in CSR-induced DSB generation.

Show MeSH
Related in: MedlinePlus