YAPping about and not forgetting TAZ

The Hippo pathway has emerged as a major eukaryotic signalling pathway and is increasingly the subject of intense interest, as are the key effectors of canonical Hippo signalling, YES‐associated protein (YAP) and TAZ. The Hippo pathway has key roles in diverse biological processes, including network signalling regulation, development, organ growth, tissue repair and regeneration, cancer, stem cell regulation and mechanotransduction. YAP and TAZ are multidomain proteins and function as transcriptional coactivators of key genes to evoke their biological effects. YAP and TAZ interact with numerous partners and their activities are controlled by a complex set of processes. This review provides an overview of Hippo signalling and its role in growth. In particular, the functional domains of YAP and TAZ and the complex mechanisms that regulate their protein stability and activity are discussed. Notably, the similarities and key differences are highlighted between the two paralogues including which partner proteins interact with which functional domains to regulate their activity

Regulation of the erythropoietin receptor and involvement of JAK2 in differentiation of J2E erythroid cells.

In response to erythropoietin, J2E cells proliferate and differentiate into mature hemoglobin-producing erythroid cells. Here we show that following hormonal stimulation, between 10 and 17 proteins, including the erythropoietin receptor and JAK2, were tyrosine phosphorylated immediately after exposure to the hormone. Although the receptor was only phosphorylated to 15% of its maximum with 0.1 unit/ml erythropoietin, this was sufficient to induce peak hemoglobin synthesis. The importance of JAK2 to J2E cell maturation was demonstrated by inhibiting JAK2 protein synthesis with antisense oligonucleotides; not only was erythropoietin-stimulated mitogenesis inhibited by this procedure, but differentiation was also suppressed. In addition, the activation of STAT5 paralleled the kinetics of receptor phosphorylation. During differentiation, 94% decrease in surface erythropoietin receptors was detected 48 h after ligand binding, but transcription of the receptor gene, mRNA steady-state levels, protein content, and translation rates did not alter with hormonal stimulation. We concluded from these experiments that (a) sub-maximal receptor phosphorylation is sufficient for differentiation to proceed; (b) JAK2 is required for erythropoietin-induced cell division and maturation; and (c) post-translational processing, or translocation, play important roles in controlling surface erythropoietin receptor numbers

Cycloheximide can induce bax/bak dependent myeloid cell death independently of multiple BH3-only proteins

10.1371/journal.pone.0164003PLoS ONE1111e016400

IAP antagonists target cIAP1 to induce TNFalpha-dependent apoptosis.

XIAP prevents apoptosis by binding to and inhibiting caspases, and this inhibition can be relieved by IAP antagonists, such as Smac/DIABLO. IAP antagonist compounds (IACs) have therefore been designed to inhibit XIAP to kill tumor cells. Because XIAP inhibits postmitochondrial caspases, caspase 8 inhibitors should not block killing by IACs. Instead, we show that apoptosis caused by an IAC is blocked by the caspase 8 inhibitor crmA and that IAP antagonists activate NF-kappaB signaling via inhibtion of cIAP1. In sensitive tumor lines, IAP antagonist induced NF-kappaB-stimulated production of TNFalpha that killed cells in an autocrine fashion. Inhibition of NF-kappaB reduced TNFalpha production, and blocking NF-kappaB activation or TNFalpha allowed tumor cells to survive IAC-induced apoptosis. Cells treated with an IAC, or those in which cIAP1 was deleted, became sensitive to apoptosis induced by exogenous TNFalpha, suggesting novel uses of these compounds in treating cancer