Homozygous, compound heterozygous or digenic mutations of proteasome subunits cause autoinflammatory diseases, termed proteasome-associated autoinflammatory syndromes (PRAAS). Introduction: The proteasome is a large protein complex involved in degradation of unnecessary or useless proteins. These mice are exciting new tools to study the pathophysiology of MKD and can be used to develop new therapeutic approaches, such as supplementation with isoprenoid lipids.
caused by mild infections) could quickly precipitate devastating defects in protein prenylation that lead to systemic inflammatory flares. Furthermore, as with patient-derived cell lines, Mvkmutant mouse cells are temperature-sensitive, suggesting that elevations in body temperature (e.g. These mice, like MKD patients, have defective protein prenylation and an exaggerated inflammatory response. Importantly, addition of the missing isoprenoid lipid geranylgeraniol could rescue the prenylation defect in primary cell cultures in vitroand in peritoneal macrophages in vivo.Ĭonclusion: To our knowledge, we have generated the first genetic mouse avatars of MKD. Interestingly, like patient-derived cell lines, the prenylation defect was dramatically enhanced in bone marrow cells from Mvkmutant mice after briefly culturing at higher temperature (39-40 oC). Furthermore, Mvk V377I/deI mice had slightly elevated levels of inflammatory serum cytokines, including IL-6 and G-CSF, and cultures of PBMCs and bone marrow macrophages responded more robustly to LPS stimulation than cells from control mice. This is consistent with reportedly less severe clinical disease associated with the homozygous V377I mutation.
However, in a similar pattern to patient PBMCs, Mvk V377I/deIimmune cells from blood, spleen and bone marrow had a dramatic accumulation of unprenylated Rab and Rap1A GTPases, with a much milder defect in Mvk V377I/V377Icells. Results: Homozygous mice carrying complete loss of function deletion mutations were not viable and, as expected, wildtype and heterozygous Mvkmutant mice had normal protein prenylation. For quantification of inflammatory cytokines in serum, as well as in culture supernatants from LPS-stimulated PBMCs and bone marrow macrophages, we used ELISA and multiplex cytokine bead arrays. To assess the effect of the mutations on the mevalonate pathway, we measured the accumulation of unprenylated Rab GTPases and Rap1A using an in vitroprenylation assay and western blotting. These lines were then crossed to generate homozygous Mvk V377I/V377Ior Mvk V377I/deIcompound heterozygous mice. Methods: CRISPR/Cas9 gene editing was used to generate different heterozygous mouse lines with hypomorphic mutations in exon 11 of the Mvkgene: a V377I substitution (the most frequent mutation in MKD), and 8, 13 or 91 base pair deletions. Objectives: To generate new Mvkmutant mouse models of MKD that mimic the human disease. However, the link between protein prenylation and inflammation in MKD is still far from understood, largely due to the lack of suitable genetic mouse models. We have found that protein prenylation is indeed compromised in PBMCs from patients and this defect distinguishes MKD from other periodic fever syndromes. It is believed that inflammation in MKD is triggered by shortage of isoprenoid lipids and defective prenylation of small GTPases. This pathway is responsible for cholesterol synthesis and the production of isoprenoid lipid tags required for post-translational prenylation of proteins.
MKD is caused by recessive, hypomorphic mutations in the mevalonate kinase gene ( MVK) encoding a key enzyme in the mevalonate pathway. A large offer of service- and contact points make it easy for newcomers and future citizens of East-Wuerttemberg to get started.Introduction: Mevalonate Kinase Deficiency (MKD) is a periodic fever syndrome characterised by recurrent bouts of high fever and systemic inflammation. Specialists from all around the world are always appreciated. The people in East-Wuerttemberg are open-minded and have a friendly culture of welcome.
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