How do 14-3-3 proteins work? – Gatekeeper phosphorylation and the molecular anvil hypothesis

Abstract14-3-3 proteins were the first signaling molecules to be identified as discrete phosphoserine/threonine binding modules. This family of proteins, which includes seven isotypes in human cells and up to 15 in plants, plays critical roles in cell signaling events that control progress through the cell cycle, transcriptional alterations in response to environmental cues, and programmed cell death. Despite over 30 years of research, distinct roles for most isotypes remain unknown. Though 14-3-3 proteins perform different functions for different ligands, general mechanisms of 14-3-3 action include changes in activity of bound ligands, altered association of bound ligands with other cellular components, and changes in intracellular localization of 14-3-3-bound cargo. We present a speculative model where binding of 14-3-3 to multiple sites on some ligands results in global ligand conformational changes that mediate their biological effects. For these multi-site ligands, one binding site is likely to function as a ‘gatekeeper’ whose phosphorylation is necessary for 14-3-3 binding but may not always be sufficient for full biological activity. If correct, then 14-3-3 may prove to be a bona fide phosphodependent signaling chaperone

Salvaging the septic heart through targeting the IL-6/p38 MAPK signaling network

Depression of myocardial function during severe sepsis, which currently accounts for approx. 200,000 deaths/year in the United States (1), is characterized by a decrease in contractility and a poor response to fluid therapy (2). Since the md-1980s it has been recognized that the decreased cardiac function, which undoubtedly contributes to the overall pathophysiology of the septic state, does not arise from factors that are intrinsic to the myocardium, but instead results from the presence of circulating myocardial depressant factors (3, 4). Since much of the massive inflammation and multi-organ dysfunction in sepsis result from the secretion of various cytokines, it was long suspected that these proteins were also responsible, at least in part, for the observed myocardial dysfunction, although their identification, and the molecular basis for their effects on myocyte function were poorly understood

14-3-3 Proteins, FHA Domains and BRCT Domains in the DNA Damage Response

The DNA damage response depends on the concerted activity of protein serine/threonine kinases and modular phosphoserine/threonine-binding domains to relay the damage signal and recruit repair proteins. The PIKK family of protein kinases, which includes ATM/ATR/DNA-PK, preferentially phosphorylate Ser-Gln sites, while their basophilic downstream effecter kinases, Chk1/Chk2/MK2 preferentially phosphorylate hydrophobic-X-Arg-X-X-Ser/Thr-hydrophobic sites. A subset of tandem BRCT domains act as phosphopeptide binding modules that bind to ATM/ATR/DNA-PK substrates after DNA damage. Conversely, 14-3-3 proteins interact with substrates of Chk1/Chk2/MK2. FHA domains have been shown to interact with substrates of ATM/ATR/DNA-PK and CK2. In this review we consider how substrate phsophorylation together with BRCT domains, FHA domains and 14-3-3 proteins function to regulate ionizing radiation-induced nuclear foci and help to establish the G2/M checkpoint. We discuss the role of MDC1 a molecular scaffold that recruits early proteins to foci, such as NBS1 and RNF8, through distinct phosphodependent interactions. In addition, we consider the role of 14-3-3 proteins and the Chk2 FHA domain in initiating and maintaining cell cycle arrest

The Emergence of Commercial Scale Offshore Wind: Progress Made and Challenges Ahead

This Article examines the offshore wind development process from leasing and permitting to electric power supply and interconnection. Willing developers may divide the process into three discrete, but not necessarily sequential, endeavors. First, the developer must secure a viable purchaser or market for the output. “Offshore wind energy” is a more complex commercial product than one might envision—it includes the actual electric energy produced, the electric generating capacity that is available to serve load, and both the environmental and clean energy attributes of wind energy. The environmental and clean energy attributes may have an economic and regulatory value separate from, or in addition to, the value of the electric energy itself. These separate complexities give rise to several questions: What are the available markets for actual offshore wind energy? How does a developer find a buyer (off-taker) for the offshore wind electric output? How are the markets for the actual energy and the environmental attributes, normally embodied in a “renewable energy certificate” (REC), combined or otherwise related? How much control can individual states exercise over the decisions of an individual utility or other purchasers of offshore wind energy and RECs (or each of them separately)? If the average cost to the developer of electric energy generation from offshore wind per kilowatt-hour (kWh) is substantially higher than the average cost of energy in the onshore markets, what features of state regulation or policy facilitate the sale? Second, the developer must secure, or acquire by sale or assignment, appropriate offshore sites for development of the physical resource. Most available offshore wind resources are located in the OCS and will be under federal control for leasing. Developers must secure OCS leases either through successful bids in the initial offering or through a later acquisition or assignment from winning bidders. Offshore wind development requires large areas within which to erect the number of turbines needed, as well as a gathering system of cables and substations, to collect and deliver the output of all the turbines via transmission lines to interconnections with the existing mainland grid. The developer also must obtain rights-of-way to lay cable for its gathering and transmission facilities—on the OCS and across state submerged lands and coastal areas. In the alternative, a new offshore wind transmission system may be built by a third party to connect with multiple wind farms and deliver energy to an onshore point of interconnection. These leasing and project configuration scenarios present many questions. If the offshore wind developer and the transmission facility developer are separate entities, how much coordination is required? What is the appropriate scope of environmental impact studies needed in connection with the OCS leasing process? What are the mechanics for acquiring the necessary property rights and leases between winning bidders and other interested developers? Third, the offshore wind developer, alone or with a third-party transmission developer, must be concerned about the interconnection of the offshore cable to the onshore transmission grid. Most onshore transmission and distribution grids were planned, constructed and operated on the assumption that electricity consumers on the coast are the end of the delivery line. While transmission grids are somewhat more robust at these isolated coastal locations—particularly when large nuclear and fossil generation exists at water’s edge—these more robust coastal grid systems are limited and may be neither geographically nor electrically proximate to offshore wind generation locations. With advances in turbine technology and the overall economics of offshore wind farm development most proposed commercial-scale projects are likely to have generation capacity in the hundreds of megawatts (MWs). Typically, interconnection of offshore wind and related transmission delivery facilities require not only reconfiguration and enlargement of the receiving onshore transmission grid to accept the input of such electric capacity at water’s edge, but also delivery to load centers that may be located a substantial distance inland. Owners of the onshore grid may not be the same as the utility purchaser or other off-taker of the offshore electric energy. The complexities of onshore interconnection raise vexing questions, such as: (i) how to reconfigure and enlarge the grid to interconnect with offshore generation, accept the energy output, and deliver to load centers; and (ii) who should bear the costs of that reconfiguration and enlargement. This Article is intended to provide a helpful roadmap or guidance for major issues in three principal areas—securing a viable purchaser, siting the offshore development farm, and onshore interconnection of the offshore cable. To date, most offshore wind development efforts in the United States occur off the Northeast and Mid-Atlantic coast. This Article highlights the emerging federal-state dynamic in the development of offshore wind generation and illuminates several key uncertainties developers face today

Energy barrier in the two-Higgs model

The electroweak model is extended by a second Higgs doublet and a numerical investigation of static, finite energy classical solutions is performed. The results indicate that for a large domain of the parameters of the Higgs potential, the energy barrier between topologically distinct vacua of the Lagrangian is constituted by a bisphaleron.Comment: 19 pages, including 4 eps figures, LaTex format, new results include

From Instantons to Sphalerons: Time-Dependent Periodic Solutions of SU(2)-Higgs Theory

We solve numerically for periodic, spherically symmetric, classical solutions of SU(2)-Higgs theory in four-dimensional Euclidean space. In the limit of short periods the solutions approach tiny instanton-anti-instanton superpositions while, for longer periods, the solutions merge with the static sphaleron. A previously predicted bifurcation point, where two branches of periodic solutions meet, appears for Higgs boson masses larger than $3.091 M_W$.Comment: 14 pages, RevTeX with eps figure

Cytokine-Induced Signaling Networks Prioritize Dynamic Range over Signal Strength

SummarySignaling networks respond to diverse stimuli, but how the state of the signaling network is relayed to downstream cellular responses is unclear. We modeled how incremental activation of signaling molecules is transmitted to control apoptosis as a function of signal strength and dynamic range. A linear relationship between signal input and response output, with the dynamic range of signaling molecules uniformly distributed across activation states, most accurately predicted cellular responses. When nonlinearized signals with compressed dynamic range relay network activation to apoptosis, we observe catastrophic, stimulus-specific prediction failures. We develop a general computational technique, “model-breakpoint analysis,” to analyze the mechanism of these failures, identifying new time- and stimulus-specific roles for Akt, ERK, and MK2 kinase activity in apoptosis, which were experimentally verified. Dynamic range is rarely measured in signal-transduction studies, but our experiments using model-breakpoint analysis suggest it may be a greater determinant of cell fate than measured signal strength

Exploiting synthetic lethal interactions for targeted cancer therapy

March 15, 2011Emerging data suggests that synthetic lethal interactions between mutated oncogenes/tumor suppressor genes and molecules involved in DNA damage signaling and repair can be therapeutically exploited to preferentially kill tumor cells. In this review, we discuss the concept of synthetic lethality, and describe several recent examples in which this concept was successfully implemented to target tumor cells in culture, in mouse models, and in human cancer patients.National Institutes of Health (U.S.) (Grant GM68762)National Institutes of Health (U.S.) (Grant CA112967)National Institutes of Health (U.S.) (Grant ES015339)National Cancer Institute (U.S.). Integrative Cancer Biology Program (Grant U54-CA112967-03)German Research Foundation (RE2246/1-1)David H. Koch Cancer Research FundGerman Kidney Foundatio

Systematic Multi-Domain Alzheimer's Risk Reduction Trial (SMARRT): Study Protocol.

This article describes the protocol for the Systematic Multi-domain Alzheimer's Risk Reduction Trial (SMARRT), a single-blind randomized pilot trial to test a personalized, pragmatic, multi-domain Alzheimer's disease (AD) risk reduction intervention in a US integrated healthcare delivery system. Study participants will be 200 higher-risk older adults (age 70-89 years with subjective cognitive complaints, low normal performance on cognitive screen, and ≥ two modifiable risk factors targeted by our intervention) who will be recruited from selected primary care clinics of Kaiser Permanente Washington, oversampling people with non-white race or Hispanic ethnicity. Study participants will be randomly assigned to a two-year Alzheimer's risk reduction intervention (SMARRT) or a Health Education (HE) control. Randomization will be stratified by clinic, race/ethnicity (non-Hispanic white versus non-white or Hispanic), and age (70-79, 80-89). Participants randomized to the SMARRT group will work with a behavioral coach and nurse to develop a personalized plan related to their risk factors (poorly controlled hypertension, diabetes with evidence of hyper or hypoglycemia, depressive symptoms, poor sleep quality, contraindicated medications, physical inactivity, low cognitive stimulation, social isolation, poor diet, smoking). Participants in the HE control group will be mailed general health education information about these risk factors for AD. The primary outcome is two-year cognitive change on a cognitive test composite score. Secondary outcomes include: 1) improvement in targeted risk factors, 2) individual cognitive domain composite scores, 3) physical performance, 4) functional ability, 5) quality of life, and 6) incidence of mild cognitive impairment, AD, and dementia. Primary and secondary outcomes will be assessed in both groups at baseline and 6, 12, 18, and 24 months

Quantum limit of deterministic theories

We show that the quantum linear harmonic oscillator can be obtained in the large $N$ limit of a classical deterministic system with SU(1,1) dynamical symmetry. This is done in analogy with recent work by G.'t Hooft who investigated a deterministic system based on SU(2). Among the advantages of our model based on a non--compact group is the fact that the ground state energy is uniquely fixed by the choice of the representation.Comment: 4 pages, 2 figures, minor corrections added. To appear in the Proceedings of Waseda International Symposium on Fundamental Physics: "New Perspectives in Quantum Physics", 12-15 November 2002, Waseda University, Tokyo, Japa