Akt Phosphorylation of BAD Couples Survival Signals to the Cell-Intrinsic Death Machinery

One signal that is overactivated in a wide range of tumour types is the production of a phospholipid, phosphatidylinositol (3,4,5) trisphosphate, by phosphatidylinositol 3-kinase (PI3K) This lipid and the protein kinase that is activated by it — AKT — trigger a cascade of responses, from cell growth and proliferation to survival and motility, that drive tumour progression Small-molecule therapeutics that block PI3K signalling might deal a severe blow to cancer cells by blocking many aspects of the tumour-cell phenotype

The phosphatidylinositol 3-Kinase AKT pathway in human cancer.

In certain aspects, the invention relates to methods for identifying compounds which modulate Akt activity mediated by the rictor-mTOR complex and methods for treating or preventing a disorder that is associated with aberrant Akt activity.

http://science.sciencemag.org/content/sci/307/5712/1098.full.pdf

Phosphorylation and regulation of Akt/PKB by the rictor-mTOR complex

Many lines of evidence suggest that mitochondria have a central role in ageing-related neurodegenerative diseases. Mitochondria are critical regulators of cell death, a key feature of neurodegeneration. Mutations in mitochondrial DNA and oxidative stress both contribute to ageing, which is the greatest risk factor for neurodegenerative diseases. In all major examples of these diseases there is strong evidence that mitochondrial dysfunction occurs early and acts causally in disease pathogenesis. Moreover, an impressive number of disease-specific proteins interact with mitochondria. Thus, therapies targeting basic mitochondrial processes, such as energy metabolism or free-radical generation, or specific interactions of disease-related proteins with mitochondria, hold great promise.

Mitochondrial dysfunction and oxidative stress in neurodegenerative diseases

The programmed cell death that occurs as part of normal mammalian development was first observed nearly a century ago (Collin 1906). It has since been established that approximately half of all neurons in the neuroaxis and >99.9% of the total number of cells generated during the course of a human lifetime go on to die through a process of apoptosis (for review, see Datta and Greenberg 1998; Vaux and Korsmeyer 1999). The induction of developmental cell death is a highly regulated process and can be suppressed by a variety of extracellular stimuli. The purification in the 1950s of the nerve growth factor (NGF), which promotes the survival of sympathetic neurons, set the stage for the discovery that peptide trophic factors promote the survival of a wide variety of cell types in vitro and in vivo (Levi-Montalcini 1987). The profound biological consequences of growth factor (GF) suppression of apoptosis are exemplified by the critical role of target-derived neurotrophins in the survival of neurons and the maintenance of functional neuronal circuits. (Pettmann and Henderson 1998). Recently, the ability of trophic factors to promote survival have been attributed, at least in part, to the phosphatidylinositide 38-OH kinase (PI3K)/c-Akt kinase cascade. Several targets of the PI3K/c-Akt signaling pathway have been recently identified that may underlie the ability of this regulatory cascade to promote survival. These substrates include two components of the intrinsic cell death machinery, BAD and caspase 9, transcription factors of the forkhead family, and a kinase, IKK, that regulates the NF-kB transcription factor. This article reviews the mechanisms by which survival factors regulate the PI3K/c-Akt cascade, the evidence that activation of the PI3K/c-Akt pathway promotes cell survival, and the current spectrum of c-Akt targets and their roles in mediating c-Akt-dependent cell survival.

/pdf/cellular-survival-a-play-in-three-akts-3wtxbzcnm7.pdf

Cellular survival: a play in three Akts

Since its discovery 10 years ago, the potential functions of protein kinase B (PKB)/AKT have been catalogued with increasing efficiency. The physiological relevance of some of the proposed mechanisms by which PKB/AKT mediates many of its effects has been questioned, and recent work using new reagents and approaches has revealed some cracks in our understanding of this important molecule, and also hinted that these effects may involve other players.

PKB/AKT: functional insights from genetic models

Wild-type PINK1 prevents basal and induced neuronal apoptosis, a protective effect abrogated by Parkinson disease-related mutations.

Over the past decade, protein kinase B (PKB, also termed Akt) has emerged as an important signaling mediator between extracellular cues and modulation of gene expression, metabolism, and cell survival. The enzyme is tightly controlled and consequences of its deregulation include loss of growth con- trol and oncogenesis. Recent work has better characterized the mechanism of PKB activation, including upstream regulators and secondary binding partners. This minireview refreshes some old concepts with new twists and highlights current out- standing questions. ! 2003 Federation of European Biochemical Societies. Pub- lished by Elsevier Science B.V. All rights reserved.

Minireview Unravelling the activation mechanisms of protein kinase B/Akt

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2803%2900562-3

Michael P. Scheid

Papers

PKB/AKT: functional insights from genetic models

Wild-type PINK1 prevents basal and induced neuronal apoptosis, a protective effect abrogated by Parkinson disease-related mutations.

Minireview Unravelling the activation mechanisms of protein kinase B/Akt

Unravelling the activation mechanisms of protein kinase B/Akt

Regulation of Bad Phosphorylation and Association with Bcl-xL by the MAPK/Erk Kinase