title: NLRP7 inter-domain interactions: the NACHT-associated domain is the physical mediator for oligomeric assembly.
abstract: Mutations in NLRP7 (NOD-like-receptor family, pyrin domain containing 7) are responsible for a type of recurrent pregnancy loss known as recurrent hydatidiform mole (HYDM1). This condition is characterized by abnormal growth of the placenta, a lack of proper embryonic development and abnormal methylation patterns at multiple imprinted loci in diploid biparental molar tissues. The role of NLRP7 protein in the disease manifestation is currently not clear. In order to better understand how the effects of HYDM1 are associated with mutations on the structure of NLRP7, we performed an inter-domain interaction screen using a yeast two-hybrid system. Additionally, we generated in silico structural models of NLRP7 in its non-activated and activated forms. Our observations from the yeast two-hybrid screen and modeling suggest that the NACHT-associated domain (NAD) of the NLRP7 protein is central to its oligomeric assembly. Upon activation, the NAD and a small part of the leucine rich repeat (LRR) of one molecule emerged out of the protective LRR domain and interact with the NACHT domain of the second molecule to form an oligomer. Furthermore, we investigated the molecular basis for the pathophysiological effect of four missense mutations, three HYDM1-causing and one rare non-synonymous variant, on the protein using confocal microscopy of transiently transfected NLRP7 in HEK293T cells and in silico structural analysis. We found that with the two clinically severe missense mutations, L398R and R693W, the normal molecule to molecule interaction was apparently affected thus decreasing their oligomerization potential while aggresome formation was increased; these changes could disturb the normal downstream functions of NLRP7 and therefore be a possible molecular effect underlying their pathophysiological impact.
authors.affiliation: Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Singer
authors.affiliation: Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany.
authors.forename: Arijit
authors.initials: A
authors.lastname: Biswas
authors.affiliation: Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Zimmer
authors.affiliation: Department of Human Genetics, McGill University Health Centre Research Institute, Montreal, Canada Department of Obstetrics and Gynecology, McGill University Health Centre Research Institute, Montreal, Canada.
authors.forename: Christiane
authors.initials: C
authors.lastname: Messaed
authors.affiliation: Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Oldenburg
authors.affiliation: Department of Human Genetics, McGill University Health Centre Research Institute, Montreal, Canada Department of Obstetrics and Gynecology, McGill University Health Centre Research Institute, Montreal, Canada.
authors.forename: Rima
authors.initials: R
authors.lastname: Slim
authors.affiliation: Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany osman.elmaarri@ukb.uni-bonn.de.
authors.forename: Osman
authors.initials: O
authors.lastname: El-Maarri
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D002460:Cell Line; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D006828:Hydatidiform Mole / Q000235:genetics*; D008958:Models, Molecular; D020125:Mutation, Missense; D009243:NAD / Q000235:genetics; D010929:Placentation; D011247:Pregnancy; D066263:Protein Aggregation, Pathological / Q000235:genetics; D017510:Protein Folding; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary; D057165:Proteostasis Deficiencies / Q000235:genetics*; D020798:Two-Hybrid System Techniques
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C502448:NLRP7 protein, human; D020033:Protein Isoforms; D009243:NAD
keywords: HYDM1-causing mutations; NLRP7; aggresome; inter-domain-interactions; protein misfolding
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