Knockdown of MVK does not lead to changes in NALP3 expression or activation

Fulvio Celsi,Sergio Crovella,Maurizio Romano,Elisa Piscianz

doi:10.1186/s12950-015-0048-5

Fulvio Celsi, Sergio Crovella + Show 2 more

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https://doi.org/10.1186/s12950-015-0048-5

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Abstract

BackgroundMutations in the Mevalonate Kinase gene (MVK) are causes of a rare autoinflammatory disease: Mevalonate Kinase Deficiency and its more acute manifestation, Mevalonic Aciduria. The latter is characterized, among other features, by neuroinflammation, developmental delay and ataxia, due to failed cerebellar development or neuronal death through chronic inflammation. Pathogenesis of neuroinflammation in Mevalonate Kinase Deficiency and Mevalonic Aciduria has not yet been completely clarified, however different research groups have been suggesting the inflammasome complex as the key factor in the disease development. A strategy to mimic this disease is blocking the mevalonate pathway, using HMG-CoA reductase inhibitors (Statins), while knock-out mice for Mevalonate Kinase are non-vital and their hemyzygous (i.e only one copy of gene preserved) littermate display almost no pathological features.FindingsWe sought to generate a murine cellular model closely resembling the pathogenic conditions found in vivo, by direct silencing of Mevalonate Kinase gene. Knockdown of Mevalonate Kinase in a murine microglial cellular model (BV-2 cells) results in neither augmented NALP3 expression nor increase of apoptosis. On the contrary, statin treatment of BV-2 cells produces an increase both in Mevalonate Kinase and NALP3 expression.ConclusionsMKD deficiency could be due or affected by protein accumulation leading to NALP3 activation, opening novel questions about strategies to tackle this disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s12950-015-0048-5) contains supplementary material, which is available to authorized users.

Highlights

Mevalonate Kinase is a key enzyme in the cholesterol biosynthetic pathway and is responsible for converting mevalonic acid to mevalonate-5-phosphate, an early intermediate in sterol and isoprenoid synthesis
After different time-course experiments we found that at 72h post-transfection Mevalonate Kinase gene (MVK) mRNA was reduced 10fold in cells treated with 8b silencing RNA (siRNA) and 6-fold with 8c siRNA (Figure 1a, left)
We found that siRNA treatment did not significantly increase caspase-1 activity 72h after transfection compared to untreated cells (Additional file 1: Figure S1a)

Summary

Introduction

Mevalonate Kinase is a key enzyme in the cholesterol biosynthetic pathway and is responsible for converting mevalonic acid to mevalonate-5-phosphate, an early intermediate in sterol and isoprenoid synthesis. A cellular model have been developed, where the mevalonate pathway is pharmacologically targeted using HMG-CoA blockers (statins), mimicking some of the inflammatory features observed in cells from patients [4]. Using this strategy, our group and other authors have found that, in different cell lines, NALP3 inflammasome activation is responsible for initiating inflammation [4,5,6]. Mutations in the Mevalonate Kinase gene (MVK) are causes of a rare autoinflammatory disease: Mevalonate Kinase Deficiency and its more acute manifestation, Mevalonic Aciduria The latter is characterized, among other features, by neuroinflammation, developmental delay and ataxia, due to failed cerebellar development or neuronal death through chronic inflammation. A strategy to mimic this disease is blocking the mevalonate pathway, using HMG-CoA reductase inhibitors (Statins), while knock-out mice for Mevalonate Kinase are non-vital and their hemyzygous (i.e only one copy of gene preserved) littermate display almost no pathological features

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