Neuronal apoptosis inhibitory protein (NAIP) localizes to the cytokinetic machinery during cell division

Francisco Abadía-Molina,Alex Mackenzie,Francisco Martín,Stephen D Baird,Virginia Morón-Calvente,Fahad Shamim

doi:10.1038/srep39981

Abstract

The neuronal apoptosis inhibitory protein (NAIP) is a constituent of the inflammasome and a key component of the innate immune system. Here we use immunofluorescence to position NAIP within the cytokinetic apparatus, contiguous to chromosomal passenger complex (CPC), Centralspindlin, PRC1 and KIF4A. During metaphase, NAIP accumulates in the mitotic spindle poles and is shown in spindle microtubules; in anaphase NAIP is detected in the middle of the central spindle. At the end of cytokinesis, NAIP is localized in the outlying region of the stem body, the center of the intercellular bridge formed between daughter cells prior to cellular abscission. We also describe the sustained presence of NAIP mRNA and protein throughout the cell cycle with a significant increase observed in the G2/M phase. Consistent with a role for NAIP in cytokinesis, NAIP overexpression in HeLa cells promotes the acquisition of a multinuclear phenotype. Conversely, NAIP siRNA gene silencing results in an apoptotic lethal phenotype. Our confocal and super resolution stimulated-emission-depletion (STED) examination of mammalian cell cytokinesis demonstrate a potential new role for NAIP in addition to anti-apoptotic and innate immunology functions.

Highlights

Centralspindlin[33,34], a hetero-tetramer which consists of two dimers of the Rho-family GTPase activating protein (GAP) MgcRacGAP, and the kinesin motor protein KIF23, is involved in the bundling of central spindle microtubules serving as the link between the central spindle and the plasma membrane during cytokinesis[35]
In this detailed microscopic analysis we report the unanticipated co-localization of NAIP with the cytokinetic machinery throughout all stages of the final step in cell division in a pattern distinct from previously characterized regulators of cytokinesis
We show here by immune localization, the presence of NAIP within subcellular structures associated with cell division

Summary

Introduction

Centralspindlin[33,34], a hetero-tetramer which consists of two dimers of the Rho-family GTPase activating protein (GAP) MgcRacGAP, and the kinesin motor protein KIF23 ( known as MKLP1), is involved in the bundling of central spindle microtubules serving as the link between the central spindle and the plasma membrane during cytokinesis[35]. In this detailed microscopic analysis we report the unanticipated co-localization of NAIP with the cytokinetic machinery throughout all stages of the final step in cell division in a pattern distinct from previously characterized regulators of cytokinesis. The molecular dissection of the novel role for NAIP in cytokinesis suggested by our data may lead to a better understanding of this critical cellular process

Methods

Results

Conclusion