Skip to main content

Influence of the naturally occurring human CASP1 variant L265S on subcellular distribution and pyroptosis

Introduction

Patients with unexplained recurrent febrile episodes and CASP1 variants suffer from systemic sterile inflammation despite altered enzymatic activity of procaspase-1 and reduced IL-1β release. Most recent findings from our group indicate that the proinflammatory effects of CASP1 variants with reduced or abrogated enzymatic activity could be due to receptor interacting protein kinase 2 (RIP2) mediated increase of NF-kB activation. These findings are additionally supported by a trend to elevated IL-6 and TNF-α expression in patients with CASP1 variants.

Objectives

The objective of this project is the identification of possible subcellular mechanisms how the CASP1-L265S variant influences proinflammatory cell death (pyroptosis) and IL-1β secretion.

Methods

We established an in vitro model of a virally transduced human monocytic cell line (THP-1 with shRNA knock-down of endogenous procaspase-1), expressing either wild type or enzymatically inactive (L265S) procaspase-1 fusion-reporter proteins and characterized them after NLRP3-inflammasome stimulation. Using confocal microscopy and in vivo live cell imaging we analyzed the subcellular distribution of fluorescently labeled procaspase-1 wildtype and variant as well as the interaction with ASC.

Results

First results revealed a disturbed nuclear localization of the CASP1-L265S variant compared to procaspase-1 wildtype. Furthermore, CASP1-L265S variant revealed a strongly decreased pyroptosome formation and a less intense interaction with ASC (apoptosis-associated speck-like protein containing a CARD) after NLRP3-stimulation. Variant procaspase-1 L265S and ASC formed smaller pyroptosomes than wildtype procaspase-1and ASC.

Conclusion

Those findings suggest a model, in which variant procaspase-1 L265S impairs nuclear localization, pyroptosome formation and ASC-interaction, leading all together to reduced IL-1β production and secretion.

Author information

Affiliations

Authors

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

The Creative Commons Public Domain Dedication waiver (https://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Rabe, S., Heymann, M., Stein, R. et al. Influence of the naturally occurring human CASP1 variant L265S on subcellular distribution and pyroptosis. Pediatr Rheumatol 13, O61 (2015). https://doi.org/10.1186/1546-0096-13-S1-O61

Download citation

  • Published:

  • DOI: https://doi.org/10.1186/1546-0096-13-S1-O61

Keywords

  • Subcellular Distribution
  • Live Cell Imaging
  • Receptor Interact Protein
  • Monocytic Cell Line
  • Human Monocytic Cell