In just three years, the green fluorescent protein (GFP) from the jellyfish Aequorea victoria has vaulted from obscurity to become one of the most widely studied and exploited proteins in biochemistry and cell biology. Its amazing ability to generate a highly visible, efficiently emitting internal fluorophore is both intrinsically fascinating and tremendously valuable. High-resolution crystal structures of GFP offer unprecedented opportunities to understand and manipulate the relation between protein structure and spectroscopic function. GFP has become well established as a marker of gene expression and protein targeting in intact cells and organisms. Mutagenesis and engineering of GFP into chimeric proteins are opening new vistas in physiological indicators, biosensors, and photochemical memories.

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The green fluorescent protein

The Nucleolus under Stress

▪ Abstract Helical membrane protein folding and oligomerization can be usefully conceptualized as involving two energetically distinct stages—the formation and subsequent side-to-side association of independently stable transbilayer helices. The interactions of helices with the bilayer, with prosthetic groups, and with each other are examined in the context of recent evidence. We conclude that the two-stage concept remains useful as an approach to simplifying discussions of stability, as a framework for folding concepts, and as a basis for understanding membrane protein evolution.

http://www.ibpc.fr/UMR7099/Publis/pdf/Popot00.pdf

Helical Membrane Protein Folding, Stability, and Evolution

A common need for microbial cells is the ability to respond to potentially toxic environmental insults. Here we review the progress in understanding the response of the yeast Saccharomyces cerevisiae to two important environmental stresses: heat shock and oxidative stress. Both of these stresses are fundamental challenges that microbes of all types will experience. The study of these environmental stress responses in S. cerevisiae has illuminated many of the features now viewed as central to our understanding of eukaryotic cell biology. Transcriptional activation plays an important role in driving the multifaceted reaction to elevated temperature and levels of reactive oxygen species. Advances provided by the development of whole genome analyses have led to an appreciation of the global reorganization of gene expression and its integration between different stress regimens. While the precise nature of the signal eliciting the heat shock response remains elusive, recent progress in the understanding of induction of the oxidative stress response is summarized here. Although these stress conditions represent ancient challenges to S. cerevisiae and other microbes, much remains to be learned about the mechanisms dedicated to dealing with these environmental parameters.

https://www.genetics.org/content/genetics/190/4/1157.full.pdf

The Response to Heat Shock and Oxidative Stress in Saccharomyces cerevisiae

Marc Vendrell,*,†,⊥ Duanting Zhai,‡ Jun Cheng Er,‡,§ and Young-Tae Chang*,†,‡ †Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), 11 Biopolis Way, 138667 Singapore ‡Department of Chemistry and MedChem Program for Life Sciences, National University of Singapore, 3 Science Drive 3, 117543 Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences, #05-01, 28 Medical Drive, 117456 Singapore

Combinatorial Strategies in Fluorescent Probe Development

Cytoplasmic stress granules: Dynamic modulators of cell signaling and disease.

Gold nanoparticles (AuNPs) are excellent tools for cancer cell imaging and basic research. However, they have yet to reach their full potential in the clinic. At present, we are only beginning to understand the molecular mechanisms that underlie the biological effects of AuNPs, including the structural and functional changes of cancer cells. This knowledge is critical for two aspects of nanomedicine. First, it will define the AuNP-induced events at the subcellular and molecular level, thereby possibly identifying new targets for cancer treatment. Second, it could provide new strategies to improve AuNP-dependent cancer diagnosis and treatment. Our review summarizes the impact of AuNPs on selected subcellular organelles that are relevant to cancer therapy. We focus on the nucleus, its subcompartments, and mitochondria, because they are intimately linked to cancer cell survival, growth, proliferation and death. While non-targeted AuNPs can damage tumor cells, concentrating AuNPs in particular subcellular locations will likely improve tumor cell killing. Thus, it will increase cancer cell damage by photothermal ablation, mechanical injury or localized drug delivery. This concept is promising, but AuNPs have to overcome multiple hurdles to perform these tasks. AuNP size, morphology and surface modification are critical parameters for their delivery to organelles. Recent strategies explored all of these variables, and surface functionalization has become crucial to concentrate AuNPs in subcellular compartments. Here, we highlight the use of AuNPs to damage cancer cells and their organelles. We discuss current limitations of AuNP-based cancer research and conclude with future directions for AuNP-dependent cancer treatment.

/pdf/off-to-the-organelles-killing-cancer-cells-with-targeted-1kdge2x7kc.pdf

Off to the organelles - killing cancer cells with targeted gold nanoparticles.

Nuclear transport of macromolecules is regulated by the physiological state of the cell and thus sensitive to stress. To define the molecular mechanisms that control nuclear export upon stress, cel...

/pdf/oxidative-stress-inhibits-nuclear-protein-export-by-multiple-17fdvc7xnc.pdf

Oxidative Stress Inhibits Nuclear Protein Export by Multiple Mechanisms That Target FG Nucleoporins and Crm1

Stress modifies all aspects of cellular physiology, including the targeting of macromolecules to the nucleus. To determine how distinct types of stress affect classical nuclear protein import, we followed the distribution of NLS-GFP, a reporter protein containing a classical nuclear localization sequence (NLS) fused to green fluorescent protein GFP. Nuclear accumulation of NLS-GFP requires import to be constitutively active; inhibition of import redistributes NLS-GFP throughout the nucleus and cytoplasm. In the yeast Saccharomyces cerevisiae, starvation, heat shock, ethanol and hydrogen peroxide rapidly inhibited classical nuclear import, whereas osmotic stress had no effect. To define the mechanisms underlying the inhibition of classical nuclear import, we located soluble components of the nuclear transport apparatus. Failure to accumulate NLS-GFP in the nucleus always correlated with a redistribution of the small GTPase Gsp1p. Whereas predominantly nuclear under normal conditions, Gsp1p equilibrated between nucleus and cytoplasm in cells exposed to starvation, heat, ethanol or hydrogen peroxide. Furthermore, analysis of yeast strains carrying mutations in different nuclear transport factors demonstrated a role for NTF2, PRP20 and MOG1 in establishing a Gsp1p gradient, as conditional lethal alleles of NTF2 and PRP20 or a deletion of MOG1 prevented Gsp1p nuclear accumulation. On the basis of these results, we now propose that certain types of stress release Gsp1p from its nuclear anchors, thereby promoting a collapse of the nucleocytoplasmic Gsp1p gradient and inhibiting classical nuclear protein import.

Stress-mediated inhibition of the classical nuclear protein import pathway and nuclear accumulation of the small GTPase Gsp1p.

https://www.cell.com/trends/biochemical-sciences/pdf/S0968-0004(19)30231-2.pdf

Ursula Stochaj

Papers

Cytoplasmic stress granules: Dynamic modulators of cell signaling and disease.

Off to the organelles - killing cancer cells with targeted gold nanoparticles.

Oxidative Stress Inhibits Nuclear Protein Export by Multiple Mechanisms That Target FG Nucleoporins and Crm1

Stress-mediated inhibition of the classical nuclear protein import pathway and nuclear accumulation of the small GTPase Gsp1p.

The Cytoskeleton as Regulator of Cell Signaling Pathways.