Defining the role of cytoskeletal components in the formation of apoptopodia and apoptotic bodies during apoptosis
During apoptosis, dying cells undergo dynamic morphological changes that ultimately lead to their disassembly into fragments called apoptotic bodies (ApoBDs). Reorganisation of the cytoskeletal structures is key in driving various apoptotic morphologies, including the loss of cell adhesion and membrane bleb formation. However, whether cytoskeletal components are also involved in morphological changes that occur later during apoptosis, such as the recently described generation of thin apoptotic membrane protrusions called apoptopodia and subsequent ApoBD formation, is not well defined. Through monitoring the progression of apoptosis by confocal microscopy, specifically focusing on the apoptopodia formation step, we characterised the presence of F-actin and microtubules in a subset of apoptopodia generated by T cells and monocytes. Interestingly, targeting actin polymerisation and microtubule assembly pharmacologically had no major effect on apoptopodia formation. These data demonstrate apoptopodia as a novel type of membrane protrusion that could be formed in the absence of actin polymerisation and microtubule assembly.
KeywordsApoptotic bodies Apoptotic cell disassembly Apoptotic morphology Apoptopodia Cytoskeletal components Membrane protrusions
We thank the La Trobe BioImaging Platform for access to microscopy and flow cytometry equipment and assistance with microscopy. We thank Dr Hendrika Duivenvoorden for her assistance with 3D cultures. This work was supported by grants from the National Health & Medical Research Council of Australia (GNT1141732, GNT1125033, GNT1140187), Australian Research Council (DP170103790) and La Trobe University (RFA2018).
SC, GKAS and IKHP designed and performed experiments with assistance from co-authors. AB generated and performed experiments on vimentin deficient cells. SC, GKAS and IKHP wrote the manuscript with input from co-authors.
Compliance with ethical standards
The authors declare no competing financial interests.