- Caspase-2 is activated in the nucleolus
Caspase-2 appears to be activated by the PIDDosome, but the role of PIDD in this pathway remains controversial. Ando et al. demonstrate that caspase-2 can be activated by two distinct complexes: one in the nucleolus that comprises PIDD and the nucleolar phosphoprotein NPM1, and one in the cytoplasm that is PIDD independent. Therefore, the nucleolus is a novel site for caspase-2 activation that appears to be essential for caspase-2 function.
- Polarized dynamics of intermediate filaments
Intermediate filaments (IFs) participate in directed cell migration, but how the IF network becomes polarized in motile cells is unclear. Leduc and Etienne-Manneville show that the turnover of IF mainly relies on actin-driven retrograde flow and microtubule-driven anterograde and retrograde transport. During cell migration, Cdc42-mediated polarity signaling inhibits dynein-dependent transport to promote the polarization of the IF network.
- Role of COPII vesicles in collagen trafficking
The coat protein complex II (COPII) is essential for the secretion of large cargo, such as procollagen I (PC1), but evidence that COPII vesicles act as PC1 transport carriers from the ER was lacking. Using high-resolution microscopy and in vitro reconstituted vesicle budding assays, Gorur et al. show that COPII vesicles carry PC1.
- GOP-1 promotes apoptotic cell degradation
Rab2 regulates multiple membrane traffic processes, but how it is recruited to and activated on the target membrane remains unclear. Here, Yin et al. identify a conserved protein, GOP-1, that activates UNC-108/Rab2 to promote phagosome, endosome, and DCV maturation.
- Integrin cooperation regulates wound vasculature
The development of novel therapies to promote wound healing is hindered by our poor understanding of how different integrins function together in the epidermis. Longmate et al. show that cross-suppression by integrins within the epidermis controls paracrine signals that regulate wound angiogenesis. Integrin α9β1 suppresses the proangiogenic functions of α3β1 during late-stage wound healing, leading to the normalization of blood vessel density in the wound bed.
- Origins of antagonistic neurotrophin signaling
Keeler and Deppmann preview work from Foldi et al. that describes some of the cellular mechanisms governing the induction of survival and death decisions by Drosophila neurotrophic factors.
- A timeline for C. elegans ciliogenesis
Centrioles are known to be essential for cilia assembly. However, their contribution has not been clearly defined. Serwas et al. show that centrioles degenerate early in C. elegans ciliogenesis. Ciliary structures are not completely formed at this time, indicating that cilia maturation does not depend on intact centrioles.