Essential Role for Epidermal Growth Factor Receptor in Glutamate Receptor Signaling to NF- B

Glutamate is a critical neurotransmitter of the central nervous system (CNS) and also an important regulator of cell survival and proliferation. The binding of glutamate to metabotropic glutamate receptors induces signal transduction cascades that lead to gene-specific transcription. The transcription factor NF-κB, which regulates cell proliferation and survival, is activated by glutamate; however, the glutamate receptor-induced signaling pathways that lead to this activation are not clearly defined. Here we investigate the glutamate-induced activation of NF-κB in glial cells of the CNS, including primary astrocytes. We show that glutamate induces phosphorylation, nuclear accumulation, DNA binding, and transcriptional activation function of glial p65. The glutamate-induced activation of NF-κB requires calcium-dependent IκB kinase α (IKKα) and IKKβ activation and induces p65-IκBα dissociation in the absence of IκBα phosphorylation or degradation. Moreover, glutamate-induced IKK preferentially targets the phosphorylation of p65 but not IκBα. Finally, we show that the ability of glutamate to activate NF-κB requires cross-coupled signaling with the epidermal growth factor receptor. Our results provide insight into a glutamate-induced regulatory pathway distinct from that described for cytokine-induced NF-κB activation and have important implications with regard to both normal glial cell physiology and pathogenesis

IKK-dependent, NF-κB-independent control of autophagic gene expression

The induction of mammalian autophagy, a cellular catabolic bulk-degradation process conserved from humans to yeast, was recently shown to require IKK, the upstream regulator of the NF-κB pathway. Interestingly, it was shown that this response did not involve classic NF-κB. Thus, the mechanism by which IKK promotes stimulus-induced autophagy is largely unknown. Here we investigate the role of IKK/NF-κB in response to nutrient deprivation, the classic autophagy-inducing stimulus. IKK and both the classic and non-canonical pathways of NF-κB are robustly induced in response to cellular starvation. Notably, cells lacking either catalytic subunit of IKK (IKKα or IKKβ) fail to induce autophagy in response to cellular starvation. Importantly, we show that IKK activity but not NF-κB, controls basal expression of the pro-autophagic gene LC3. We further demonstrate that starvation induces the expression of LC3 and two other essential autophagic genes, ATG5 and Beclin-1, in an IKK-dependent manner. These results demonstrate that the IKK complex is a central mediator of starvation-induced autophagy in mammalian cells and suggest that this requirement occurs at least in part through the regulation of autophagic gene expression. Interestingly, NF-κB subunits are dispensable for both basal and starvation-induced expression of pro-autophagic genes. However, starvation-induced activation of NF-κB is not inconsequential as increases in expression of anti-apoptotic NF-κB target genes such as cIAP2 is observed in response to cellular starvation. Thus, IKK likely plays multiple roles in response to starvation by regulating NF-κB-dependent anti-apoptotic gene expression as well as controlling expression of autophagic genes through a yet undetermined mechanism

Calorie restriction alters mitochondrial protein acetylation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72130/1/j.1474-9726.2009.00503.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/72130/2/ACEL_503_sm_FigS1.pd

Dihydropyrimidine Accumulation Is Required for the Epithelial-Mesenchymal Transition

It is increasingly appreciated that oncogenic transformation alters cellular metabolism to facilitate cell proliferation, but less is known about the metabolic changes that promote cancer cell aggressiveness. Here, we analyzed metabolic gene expression in cancer cell lines and found that a set of high-grade carcinoma lines expressing mesenchymal markers share a unique 44 gene signature, designated the “mesenchymal metabolic signature” (MMS). A FACS-based shRNA screen identified several MMS genes as essential for the epithelial-mesenchymal transition (EMT), but not for cell proliferation. Dihydropyrimidine dehydrogenase (DPYD), a pyrimidine-degrading enzyme, was highly expressed upon EMT induction and was necessary for cells to acquire mesenchymal characteristics in vitro and for tumorigenic cells to extravasate into the mouse lung. This role of DPYD was mediated through its catalytic activity and enzymatic products, the dihydropyrimidines. Thus, we identify metabolic processes essential for the EMT, a program associated with the acquisition of metastatic and aggressive cancer cell traits.United States. National Institutes of Health (RO1 CA103866)United States. National Institutes of Health (AI047389)United States. National Institutes of Health (K99 CA168940)American Cancer Society (PF-12-099-01-TGB)American Cancer Society (PF-13-356-01-TBE)United States. Department of Defense (BC123066)United States. National Institutes of Health (CA112967)United States. National Institutes of Health (ES015339

Pattern Formation in Interface Depinning and Other Models: Erratically Moving Spatial Structures

We study erratically moving spatial structures that are found in a driven interface in a random medium at the depinning threshold. We introduce a bond-disordered variant of the Sneppen model and study the effect of extremal dynamics on the morphology of the interface. We find evidence for the formation of a structure which moves along with the growth site. The time average of the structure, which is defined with respect to the active spot of growth, defines an activity-centered pattern. Extensive Monte Carlo simulations show that the pattern has a tail which decays slowly, as a power law. To understand this sort of pattern formation, we write down an approximate integral equation involving the local interface dynamics and long-ranged jumps of the growth spot. We clarify the nature of the approximation by considering a model for which the integral equation is exactly derivable from an extended master equation. Improvements to the equation are considered by adding a second coupled equation which provides a self-consistent description. The pattern, which defines a one-point correlation function, is shown to have a strong effect on ordinary space-fixed two-point correlation functions. Finally we present evidence that this sort of pattern formation is not confined to the interface problem, but is generic to situations in which the activity at succesive time steps is correlated, as for instance in several other extremal models. We present numerical results for activity-centered patterns in the Bak-Sneppen model of evolution and the Zaitsev model of low-temperature creep.Comment: RevTeX, 18 pages, 19 eps-figures, To appear in Phys. Rev.

Does the transcription factor AP-2β have an impact on the genetic and early environmental influence on ethanol consumption?

Genes involved in alcoholism have consensus sites for the transcription factor activator protein (TFAP) 2β. In the present study, we investigated TFAP-2β protein levels in the ethanol-preferring alko, alcohol (AA) and the ethanol-avoiding alko, non-alcohol (ANA) rat lines. Furthermore, basal and ethanol-induced TFAP-2β levels were examined in Wistar rats exposed to different early postnatal environments that are known to affect later ethanol consumption. Taken together, we found differences in brainstem TFAP-2β protein between the AA and ANA rats

Analysis of neuropeptide gene expression by transfection of DNA into cell lines

The transcriptional regulation of neuropeptide genes by cAMP is often directed by a cAMP responsive enhancer (CRE) upstream to the promoter of the genes. The identity of the CRE was determined by transient transfection experiments and has the consensus sequence of 5′-TGACGTCA-3′. A large family of transcription factors have been identified which recognize the CRE. Transient transfection assays that employed expression of these factors driven by viral promoters have determined they can transactivate the neuropeptide gene promoters. Because of the large number of factors that have been identified as being able to recognize the CRE, it has been difficult to determine which factors mediate in vivo the transactivation of a particular CRE. Using a dominant negative mutant of one of these factors, CREB, it has been determined that both CREB as well as other factors which do not interact with CREB may mediate the cAMP response of the somatostatin gene.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43232/1/11022_2005_Article_BF01667368.pd

Reaction-diffusion fronts under stochastic advection

We study front propagation in stirred media using a simplified modelization of the turbulent flow. Computer simulations reveal the existence of the two limiting propagation modes observed in recent experiments with liquid phase isothermal reactions. These two modes respectively correspond to a wrinkled although sharp propagating interface and to a broadened one. Specific laws relative to the enhancement of the front velocity in each regime are confirmed by our simulations