Abstract
The availability of a genetic model organism with which to study key molecular events underlying amyloidogenesis is crucial for elucidating the mechanism of the disease and the exploration of new therapeutic avenues. The natural human variant of β2-microglobulin (D76N β2-m) is associated with a fatal familial form of systemic amyloidosis. Hitherto, no animal model has been available for studying in vivo the pathogenicity of this protein. We have established a transgenic C. elegans line, expressing the human D76N β2-m variant. Using the INVertebrate Automated Phenotyping Platform (INVAPP) and the algorithm Paragon, we were able to detect growth and motility impairment in D76N β2-m expressing worms. We also demonstrated the specificity of the β2-m variant in determining the pathological phenotype by rescuing the wild type phenotype when β2-m expression was inhibited by RNA interference (RNAi). Using this model, we have confirmed the efficacy of doxycycline, an inhibitor of the aggregation of amyloidogenic proteins, in rescuing the phenotype. In future, this C. elegans model, in conjunction with the INVAPP/Paragon system, offers the prospect of high-throughput chemical screening in the search for new drug candidates.
Highlights
Whereas the mechanism of misfolding and aggregation in vitro has been extensively clarified, the mechanism of toxicity of amyloid in general and of β2-m in particular remains an unmet challenge
We have previously described the phenotypes of transgenic worm strains transiently expressing wild type β2-microglobulin and some isoforms not related to the familial form of the disease[12]
We previously reported a C. elegans model of wild type β2-m amyloidosis in which the protein was expressed in the body-wall muscles under the control of the promoter of the myosin gene unc-5412
Summary
Whereas the mechanism of misfolding and aggregation in vitro has been extensively clarified, the mechanism of toxicity of amyloid in general and of β2-m in particular remains an unmet challenge. We characterize a new transgenic C. elegans strain, named CPV27, expressing the D76N variant, in which the β2-m gene is integrated into the C. elegans genome The development of this new strain was challenging, due to the high toxicity of the expressed protein at the embryonic stage of development. We have prepared a strain in which the expression of the disease-causing variant is under temperature-dependent control, using the well-characterized mRNA-surveillance system of C. elegans[13] This new worm strain is the first robust animal model for studying in vivo the effects of the pathogenic variant of D76N β2-m and represents a valuable new tool with which to explore further the disease mechanism and search for new drug candidates to combat β2-m amyloidogenesis
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