Uncovering a Dual Regulatory Role for Caspases During Endoplasmic Reticulum Stress-induced Cell Death.

Many diseases are associated with endoplasmic reticulum (ER) stress, which results from an accumulation of misfolded proteins. This triggers an adaptive response called the "unfolded protein response" (UPR), and prolonged exposure to ER stress leads to cell death. Caspases are reported to play a critical role in ER stress-induced cell death but the underlying mechanisms by which they exert their effect continue to remain elusive.

SUMOylation is essential for sex-specific assembly and function of the Caenorhabditis elegans dosage compensation complex on X chromosomes.

The essential process of dosage compensation equalizes X-chromosome gene expression between Caenorhabditis elegans XO males and XX hermaphrodites through a dosage compensation complex (DCC) that is homologous to condensin. The DCC binds to both X chromosomes of hermaphrodites to repress transcription by half. Here, we show that posttranslational modification by the SUMO (small ubiquitin-like modifier) conjugation pathway is essential for sex-specific assembly and function of the DCC on X.

An MLL/COMPASS subunit functions in the C. elegans dosage compensation complex to target X chromosomes for transcriptional regulation of gene expression.

Here we analyze the essential process of X-chromosome dosage compensation (DC) to elucidate mechanisms that control the assembly, genome-wide binding, and function of gene regulatory complexes that act over large chromosomal territories. We demonstrate that a subunit of Caenorhabditis elegans MLL/COMPASS, a gene activation complex, acts within the DC complex (DCC), a condensin complex, to target the DCC to both X chromosomes of hermaphrodites for chromosome-wide reduction of gene expression. The DCC binds to two categories of sites on X: rex (recruitment element on X) sites that recruit the DCC in an autonomous, sequence-dependent manner, and dox (dependent on X) sites that reside primarily in promoters of expressed genes and bind the DCC robustly only when attached to X.

A condensin-like dosage compensation complex acts at a distance to control expression throughout the genome.

In many species, a dosage compensation complex (DCC) is targeted to X chromosomes of one sex to equalize levels of X-gene products between males (1X) and females (2X). Here we identify cis-acting regulatory elements that target the Caenorhabditis elegans X chromosome for repression by the DCC. The DCC binds to discrete, dispersed sites on X of two types.