[
Worm,
2016]
Aging is accompanied by large-scale changes in the proteome, which could have important consequences for cellular and organismal physiology. In this commentary, we review recent studies characterizing the aging proteome in C. elegans. We assess the evidence that the rates of protein synthesis, folding, and degradation change with age in C. elegans, and evaluate whether changes in these pathways limit normal lifespan. We also discuss large-scale studies measuring changes in the proteome with age that suggest that a failure to excrete reproductive proteins in post-reproductive animals plays a role in changing protein levels with age.
[
Worm,
2016]
In eukaryotic organisms, gene regulation occurs in the context of chromatin. In the interphase nucleus, euchromatin and heterochromatin occupy distinct space during cell differentiation, with heterochromatin becoming enriched at the nuclear and nucleolar peripheries. This organization is thought to fine-tune gene expression. To elucidate the mechanisms that govern this level of genome organization, screens were carried out in C. elegans which monitored the loss of heterochromatin sequestration at the nuclear periphery. This led to the identification of a novel chromodomain protein, CEC-4 (Caenorhabditis elegans chromodomain protein 4) that mediates the anchoring of H3K9 methylation-bearing chromatin at the nuclear periphery in early to mid-stage embryos. Surprisingly, the loss of CEC-4 does not derepress genes found in heterochromatic domains, nor does it affect differentiation under standard laboratory conditions. On the other hand, CEC-4 contributes to the efficiency with which muscle differentiation is induced following ectopic expression of the master regulator, HLH-1. This is one of the first phenotypes specifically attributed to the ablation of heterochromatin anchoring.