Podosomes are dynamic actin-rich structures that are able to locally degrade the matrix through recruitment of matrix-lytic enzymes; this allows macrophages to cross tissue barriers and navigate through dense extracellular matrix. The podosome core has been shown to contain branched actin filaments that are nucleated by Arp2/3, but recent evidence also suggests the presence of unbranched filaments in podosomes. In their work on page 298, Stefan Linder and colleagues now show that the formins FHOD1 and INF2 localise to different podosome substructures in primary human macrophages. Using a variety of microscopy-based approaches, including a podosome reformation assay, they find that the two formins regulate different aspects of podosomes. INF2 localises to the podosome cap structure; it negatively regulates podosome size and positively affects podosomal matrix degradation. Because INF2 also regulates podosome oscillations, it most probably also plays a role in the mechanosensing ability of podosomes. FHOD1 depletion did not lead to any significant changes in overall podosome size or number, but reduced actomyosin contractility at podosome-connecting actin cables, suggesting that FHOD1 functions to regulate podosome connectivity, possibly to establish the typical regular podosome pattern at the substrate-contacting cell side. Taken together, these findings not only establish formins as new regulators of podosome function, but also highlight that these structures represent an excellent model system for the analysis of complex actin architectures in cells.
Formins help podosomes form Free
Formins help podosomes form. J Cell Sci 15 January 2016; 129 (2): e0201. doi:
Download citation file:
Advertisement
Cited by
JCS fast-track option

Have a paper that has been reviewed elsewhere? JCS is pleased to consider such manuscripts for fast-tracked decision making. Send us your manuscript together with the full set of reviews and decision letters, and we will make an initial decision within one week.
Special Issue – Cell Biology of Mitochondria

Our special issue on ‘Cell Biology of Mitochondria’ is now complete. Explore this issue and read the Editorial from our Guest Editors Ana J. García-Sáez and Heidi McBride.
Save the date – Imaging Cell Dynamics

We are delighted to announce that we will be hosting a 2026 Imaging Cell Dynamics meeting. This meeting will provide a unique opportunity to bring together experts working at the interface between cell biology and imaging. Save the date for 11-14 May 2026 and register for more information.
Origin and evolution of mitochondrial inner membrane composition

In this Review, Kailash Venkatraman and colleagues provide an examination of the morphological similarities between prokaryotic intracytoplasmic membranes and mitochondrial inner membranes, and whether cristae evolution has driven specialisation of the mitochondrial lipidome.
Resolution in super-resolution microscopy
Super-resolution microscopy (SRM) has emerged as a powerful tool for biological discovery. In this Perspective, Kirti Prakash and colleagues compile expert opinions on crucial, yet often overlooked, aspects of SRM that are essential for maximising its benefits and advancing the field.