Viruses take center stage in cellular evolution

The origins of viruses are shrouded in mystery, but advances in genomics and the discovery of highly complex giant DNA viruses have stimulated new hypotheses that DNA viruses were involved in the emergence of the eukaryotic cell nucleus, and that they are worthy of being considered as living organisms.     

Estrogen and bone: osteoclasts take center stage

Loss of estrogen at menopause causes osteoporosis in many women, but estrogen's relevant cellular target in this process has remained unclear. In a recent study in Cell, Kato and colleagues (Nakamura et al., 2007) selectively ablate estrogen receptor alpha in osteoclasts and demonstrate that estrogen directly induces osteoclast apoptosis.     

Astrocytes take center stage in salt sensing

Spatiotemporal patterns of cortical activation occur superimposed upon sensory, motor, and cognitive maps. The papers by Benucci et al. and Xu et al. in this issue of Neuron demonstrate that visual responses propagate in space and may serve to link different visual areas. This is an important step toward understanding how cortical maps relate to activation patterns, a prerequisite to understanding visual cortex function.     

Receptor-like kinases take center stage in plant biology

正Like the animals,higher plants must perceive and interpret numerous external and endogenous cues to properly program growth and development and physiological responses.Animal cells use diverse receptors to perceive external signals to regulate cellular processes.Thus,receptor-tyrosine kinases(RTKs)are responsible for perceiving growth regu-     

Wiring and firing neuronal networks: endocannabinoids take center stage

Endocannabinoids (eCBs) function as retrograde messengers at both excitatory and inhibitory synapses, and control various forms of synaptic plasticity in the adult brain. The molecular machinery required for specific eCB functions during synaptic plasticity is well established. However, eCB signaling plays surprisingly fundamental roles in controlling the acquisition of neuronal identity during CNS development. Recent work suggests that selective recruitment of regulatory signaling networks to CB1 cannabinoid receptors dictates neuronal state-change decisions. In addition, the spatial localization and temporal precision of eCB actions emerges as a novel organizer in developing neuronal networks. Current challenges include fitting novel molecular candidates into regulatory eCB signaling pathways, and defining the temporal dynamics of context-dependent signaling mechanisms underpinning particular neuronal specification events.     

Biofuel and energy crops: high-yield Saccharinae take center stage in the post-genomics era

The Saccharinae, especially sugarcane, Miscanthus and sorghum, present remarkable characteristics for bioenergy production. Biotechnology of these plants will be important for a sustainable feedstock supply. Herein, we review knowledge useful for their improvement and synergies gained by their parallel study.     

Vps34 and PLD1 take center stage in nutrient signaling: their dual roles in regulating autophagy

Autophagy is a critical pathway leading to lysosomal degradation of cellular components in response to changes in nutrient availability. Autophagy includes the biogenesis of autophagosomes and their sequential maturation through fusion with endo-lysosomes. The class III PI3 kinase Vps34 and its product phosphatidylinositol-3-phosphate (PI(3)P) play a critical role in this process, and enable the amino acid-mediated activation of mammalian target of rapamycin (mTOR), a suppressor of autophagy. Recent studies have shown that phospholipase PLD1, a downstream regulator of Vps34, is also closely involved in both mTOR activation and autophagy. This mini review summarizes recent findings in the regulation of Vps34 and PLD1 and highlights the role of these lipid-metabolizing enzymes in both mTOR activation and autophagy.     

Lysophospholipids in the limelight: autotaxin takes center stage

Lysophosphatidic acid (LPA) is a serum phospholipid that evokes growth factor-like responses in many cell types through the activation of its G protein-coupled receptors. Although much is known about LPA signaling, it has remained unclear where and how bioactive LPA is produced. Umezu-Goto et al. (2002)(this issue, page 227) have purified a serum lysophospholipase D that generates LPA from lysophosphatidylcholine and found it to be identical to autotaxin, a cell motility-stimulating ectophosphodiesterase implicated in tumor progression. This result is surprising, as there was previously no indication that autotaxin could act as a phospholipase.     

Eukaryotic cells and microbial pathogens: a familiar couple take centre stage

The interaction of a microbial pathogen with its host is a highly dynamic process shaped by evolution. Understanding cellular responses to microbial products is essential for a complete understanding of virulence. Similarly, studies aimed at determining how a particular virulence factor functions have helped unravel molecular mechanisms that govern eukaryotic cellular events. These two seemingly diverse areas were brought together on the beautiful Spanish Costa Brava in a recent meeting (October 13-17, 2002) sponsored by European Research Conferences (EURESCO) and the European Molecular Biology Organization (EMBO).