Targeted ubiquitylation: the prey becomes predator

Ubiquitin and transcription: The SCF/Met4 pathway, a (protein-) complex issue

Ubiquitylation has emerged as an omnipresent factor at all levels of transcriptional regulation. A recent study that describes the yeast transcriptional activator Met4 as a functional component of the very same ubiquitin ligase that regulates its own activity highlights the close relation between transcription and the ubiquitin proteasome system.

Lipid transport between the endoplasmic reticulum and mitochondria

Mitochondria are partially autonomous organelles that depend on the import of certain proteins and lipids to maintain cell survival and membrane formation. Although phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine are synthesized by mitochondrial enzymes, phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and sterols need to be imported from other organelles. The origin of most lipids imported into mitochondria is the endoplasmic reticulum, which requires interaction of these two subcellular compartments. Recently, protein complexes that are involved in membrane contact between endoplasmic reticulum and mitochondria were identified, but their role in lipid transport is still unclear. In the present review, we describe components involved in lipid translocation between the endoplasmic reticulum and mitochondria and discuss functional as well as regulatory aspects that are important for lipid homeostasis.

Regulation and function of the TAZ transcription co-activator

TAZ (WWTR1), identified as a 14-3-3 binding protein with a PDZ binding motif, is implicated in mesenchymal stem cell differentiation. TAZ has been shown to be negatively regulated by phosphorylation-dependent and phosphorylation-independent mechanisms. Coupled with ASPP2, PP1 dephosphorylates TAZ to activate TAZ. TEADs mediate TAZ function in promoting cell proliferation and epithelial-mesenchymal transition (EMT). TAZ senses different cellular signals such as cell density and the extracellular matrix stiffness. Significantly, TAZ is overexpressed in breast cancer samples and papillary thyroid carcinoma tissues. These results indicate that TAZ plays an important role in cancer development and presents a novel target for TAZ overexpressed cancer therapy.