Volume 12 Issue 9, September 2010

Mounting evidence suggests that keratin post-translational modifications are crucial for many cellular processes. Now, keratin 18 modified by the addition of an O-linked N-acetylglucosamine residue is shown to be as a critical effector of stress-responsive Akt signalling, providing an important link between keratin glycosylation and cell survival.

Kinetochores link microtubules to DNA and provide force critical for chromosome segregation in mitosis. New data show that kinetochores are not necessary for acentrosomal meiotic chromosome segregation in Caenorhabditis elegans. Instead, CLS-2 (CLASP) generates a mid-zone bundle of microtubules that are suggested to act in pushing the chromosomes apart.

The role of different histone H3 variants following mouse fertilization has not been addressed. The histone H3.3, and its Lys 27 are involved in the establishment of paternal heterochromatin in the pericentric region of the mouse early embryo, through a mechanism involving dsRNA.

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) lead to accumulation of proteins aggregates in airways. Mutated CFTR promotes transglutaminases-mediated crosslinking of beclin 1, a positive regulator of autophagy, to induce accumulation of LC3-binding protein p62 and prevent autophagic degradation of aggregates.

Keratin 8 and 18 protect hepatocytes from apoptosis. Inhibiting keratin 18 glycosylation is shown to sensitize cells to liver and pancreatic injury and apoptosis, through a pathway involving Akt and PKCθ.

An RNAi screen of protein phosphatases identifies PP2A–B55α as the main mitotic exit phosphatase in human cells. After mitosis, PP2A–B55α depletion delays the reassembly of the nuclear envelope and Golgi and the decondensation of chromatin.

How acentrosomal meiotic spindles separate chromosomes in anaphase has been unclear. Although kinetochores are required for the bi-orientation of chromosomes, chromosome separation may instead be driven by CLASP/CLS-2 mediated microtubule assembly.

A cell-free system has been developed to image vesicle budding and fission events. This method reveals an important role for the F-BAR protein FBP17 in regulating tubulation and clathrin-dependent budding.

Little is known about the ultrastructure of focal adhesions, compared with their extensive molecular characterization. Cryo-electron tomography provides novel insights into the internal sub-structures at the interface between adhesions and the actin cytoskeleton.

Autophagy targets damaged organelles and proteins for lysosomal degradation. This potent degradation mechanism has crucial roles in development, immune defence, programmed cell death, tumour suppression, neurodegeneration and stress response. The September 2010 issue of Nature Cell Biologypresents a series of specially commissioned Reviews, Perspectives and Commentaries highlighting new insights into this process.