A Hypermorphic Missense Mutation in PLCG2 , Encoding Phospholipase Cγ2, Causes a Dominantly Inherited Autoinflammatory Disease with Immunodeficiency

Abstract

Whole-exome sequencing was performed in a family affected by dominantly inherited inflammatory disease characterized by recurrent blistering skin lesions, bronchiolitis, arthralgia, ocular inflammation, enterocolitis, absence of autoantibodies, and mild immunodeficiency. Exome data from three samples, including the affected father and daughter and unaffected mother, were filtered for the exclusion of reported variants, along with benign variants, as determined by PolyPhen-2. A total of eight transcripts were identified as possible candidate genes. We confirmed a variant, c.2120C>A (p.Ser707Tyr), within PLCG2 as the only de novo variant that was present in two affected family members and not present in four unaffected members. PLCG2 encodes phospholipase Cγ2 (PLCγ2), an enzyme with a critical regulatory role in various immune and inflammatory pathways. The p.Ser707Tyr substitution is located in an autoinhibitory SH2 domain that is crucial for PLCγ2 activation. Overexpression of the altered p.Ser707Tyr protein and ex vivo experiments using affected individuals' leukocytes showed clearly enhanced PLCγ2 activity, suggesting increased intracellular signaling in the PLCγ2-mediated pathway. Recently, our laboratory identified in individuals with cold-induced urticaria and immune dysregulation PLCG2 exon-skipping mutations resulting in protein products with constitutive phospholipase activity but with reduced intracellular signaling at physiological temperatures. In contrast, the p.Ser707Tyr substitution in PLCγ2 causes a distinct inflammatory phenotype that is not provoked by cold temperatures and that has different end-organ involvement and increased intracellular signaling at physiological temperatures. Our results highlight the utility of exome-sequencing technology in finding causal mutations in nuclear families with dominantly inherited traits otherwise intractable by linkage analysis.

Deutsche Gesellschaft für Experimentelle und Klinische Pharmakologie und Toxikologie e.V.

“…Thus, previous experiments performed in mouse fibroblasts revealed a c-Fos/AP-1 mediated regulation of the NER endonuclease XPF and XPG, leading to enhanced NER activity (1). Transcriptional activation of XPF, XPG and ERCC1 was also observed in human fibroblasts and was associated with increased cellular repair capacity and protection against UV-induced DNA damage (2). In addition, pre-exposure to a low nontoxic UV dose accelerated DNA repair and protected the cells against a subsequent high UV dose, indicating a protective role of transcriptional regulation by triggering an adaptive response (2).…”

“…Furthermore, even though all the inactive structures of GPCRs crystallized so far confirm the presence of the R 3.50 /D 3.49 interaction, most of them lack the expected interhelical R 3.50 /E 6.30 bond and do not clarify the role of the DRY motif and its interaction partners. Here, using a well characterized FRET-based technique [1,2], we examined the effects of the substitution of D 3.49 and E 6.30 on the α2A-AR conformation in real time. The results show that neutralization of these residues generates 2 distinct α2A-AR conformational states.…”

“…The connection between theses binding sites allowed the design of heterobivalent ligands which bind to both the orthosteric and allosteric binding site simultaneously. These so-called dualsteric ligands engender functional selectivity in favoring Gi-over Gs-signaling 2 . Here, we report on the identification of a biological function of GPCR's allosteric binding sites to 'fine-tune' GPCR signaling 3 .…”

“…Nature 482, 547-551 (2012). [2] Antony, J. et al Dualsteric GPCR targeting: a novel route to binding and signaling pathway selectivity. FASEB J.…”

“…1 In patients with deltastorage pool deficiencies, which lead to impaired function of platelets, a disturbance of the correct localization of MRP4 was observed. 2 It has been recognized that protein-protein interactions are important for transporter localization and their function. We therefore investigated protein interactions of MRP4 especially in platelets as well as its regulation on the transcriptional as well as post-transcriptional level.…”