Detection of early gene expression changes during activation of human primary lymphocytes by in vitro synthesis of proteins from polysome-associated mRNAs

A Rapid Translational Immune Response Program in CD8 Memory T Lymphocytes

The activation of memory T cells is a very rapid and concerted cellular response that requires coordination between cellular processes in different compartments and on different time scales. In this study, we use ribosome profiling and deep RNA sequencing to define the acute mRNA translation changes in CD8 memory T cells following initial activation events. We find that initial translation enables subsequent events of human and mouse T cell activation and expansion. Briefly, early events in the activation of Ag-experienced CD8 T cells are insensitive to transcriptional blockade with actinomycin D, and instead depend on the translation of pre-existing mRNAs and are blocked by cycloheximide. Ribosome profiling identifies ∼92 mRNAs that are recruited into ribosomes following CD8 T cell stimulation. These mRNAs typically have structured GC and pyrimidine-rich 5' untranslated regions and they encode key regulators of T cell activation and proliferation such as Notch1, Ifngr1, Il2rb, and serine metabolism enzymes Psat1 and Shmt2 (serine hydroxymethyltransferase 2), as well as translation factors eEF1a1 (eukaryotic elongation factor α1) and eEF2 (eukaryotic elongation factor 2). The increased production of receptors of IL-2 and IFN-γ precedes the activation of gene expression and augments cellular signals and T cell activation. Taken together, we identify an early RNA translation program that acts in a feed-forward manner to enable the rapid and dramatic process of CD8 memory T cell expansion and activation.

Prohibitin( PHB) roles in granulosa cell physiology

Ovarian granulosa cells (GC) play an important role in the growth and development of the follicle in the process known as folliculogenesis. In the present review, we focus on recent developments in prohibitin (PHB) research in relation to GC physiological functions. PHB is a member of a highly conserved eukaryotic protein family containing the repressor of estrogen activity (REA)/stomatin/PHB/flotillin/HflK/C (SPFH) domain (also known as the PHB domain) found in diverse species from prokaryotes to eukaryotes. PHB is ubiquitously expressed in a circulating free form or is present in multiple cellular compartments including mitochondria, nucleus and plasma membrane. In mitochondria, PHB is anchored to the mitochondrial inner membrane and forms complexes with the ATPases associated with proteases having diverse cellular activities. PHB continuously shuttles between the mitochondria, cytosol and nucleus. In the nucleus, PHB interacts with various transcription factors and modulates transcriptional activity directly or through interactions with chromatin remodeling proteins. Many functions have been attributed to the mitochondrial and nuclear PHB complexes such as cellular differentiation, anti-proliferation, morphogenesis and maintenance of the functional integrity of the mitochondria. However, to date, the regulation of PHB expression patterns and GC physiological functions are not completely understood.

Cardiac mitochondrial proteomic expression in inbred rat strains divergent in survival time after hemorrhage

We have previously identified inbred rat strains differing in survival time to a severe controlled hemorrhage (StaH). In efforts to identify cellular mechanisms and ultimately genes that are important contributors to enhanced STaH, we conducted a study to characterize potential differences in cardiac mitochondrial proteins in these rats. Inbred rats from three strains [Brown Norway/Medical College of Wisconsin (BN); Dark Agouti (DA), and Fawn Hooded Hypertensive (FHH)] with different StaH (DA = FHH > BN) were assigned to one of three treatment groups (n = 4/strain): nonoperated controls, surgically catheterized rats, or rats surgically catheterized and hemorrhaged 24 h postsurgery. Rats were euthanized 30 min after handling or 30 min after initiation of a 26 min hemorrhage. After euthanasia, hearts were removed and mitochondria isolated. Differential protein expression was determined using 2D DIGE-based Quantitative Intact Proteomics and proteins identified by MALDI/TOF mass spectrometry. Hundreds of proteins (791) differed among inbred rat strains (P ≤ 0.038), and of these 81 were identified. Thirty-eight were unique proteins and 43 were apparent isoforms. For DA rats (longest STaH), 36 proteins increased and 30 decreased compared with BN (shortest STaH). These 81 proteins were associated with lipid (e.g., acyl CoA dehydrogenase) and carbohydrate (e.g., fumarase) metabolism, oxidative phosphorylation (e.g., ubiquinol-cytochrome C reductase), ATP synthesis (F1 ATPase), and H2S synthesis (3-mercaptopyruvate sulfurtransferase). Although we cannot make associations between these identified mitochondrial proteins and StaH, our data do provide evidence for future candidate proteins with which to consider such associations.

Magnetic particles as powerful purification tool for high sensitive mass spectrometric screening procedures

The effective isolation and purification of proteins from biological fluids is the most crucial step for a successful protein analysis when only minute amounts are available. While conventional purification methods such as dialysis, ultrafiltration or protein precipitation often lead to a marked loss of protein, SPE with small-sized particles is a powerful alternative. The implementation of particles with superparamagnetic cores facilitates the handling of those particles and allows the application of particles in the nanometer to low micrometer range. Due to the small diameters, magnetic particles are advantageous for increasing sensitivity when using subsequent MS analysis or gel electrophoresis. In the last years, different types of magnetic particles were developed for specific protein purification purposes followed by analysis or screening procedures using MS or SDS gel electrophoresis. In this review, the use of magnetic particles for different applications, such as, the extraction and analysis of DNA/RNA, peptides and proteins, is described.

The Prohibitins: emerging roles in diverse functions

The prohibitins, Phb1 and Phb2 are highly conserved proteins in eukaryotic cells that are present in multiple cellular compartments. Initial investigations focused on the role of Phb1 as an inhibitor of cell proliferation hence the original name prohibitin. However both proteins appear to have a diverse range of functions and recent evidence suggests that the prohibitins have very similar but as yet only partially understood functions. In addition to their role as chaperone proteins in the mitochondria, and their ability to target to lipid rafts, their is now compelling evidence that both prohibitins are localized in the nucleus and can modulate transcriptional activity by interacting with various transcription factors, including the steroid hormone receptors, either directly or indirectly. In addition Phb1 and Phb2 are present in the circulation and can be internalized when added to cultured cells suggesting that the circulating prohibitins may have some regulatory role. This review presents some of the recent developments in prohibitin research and focuses on the similarities in the structure and function of these interesting proteins.

Serial analysis of gene expression in circulating gamma delta T cell subsets defines distinct immunoregulatory phenotypes and unexpected gene expression profiles

Gene expression profiles were compared in circulating bovine GD3.5+ (CD8-) and GD3.5- (predominantly CD8+) gammadelta T cells using serial analysis of gene expression (SAGE). Approximately 20,000 SAGE tags were generated from each library. A comparison of the two libraries demonstrated 297 and 173 tags representing genes with 5-fold differential expression in GD3.5+ and GD3.5- gammadelta T cells, respectively. Consistent with their localization into sites of inflammation, GD3.5+ gammadelta T cells appeared transcriptionally and translationally more active than GD3.5- gammadelta cells. GD3.5- gammadelta T cells demonstrated higher expression of the cell proliferation inhibitor BAP 37, which was associated with their less activated gene expression phenotype. The immune regulatory and apoptosis-inducing molecule, galectin-1, was identified as a highly abundant molecule and was higher in GD3.5+gammadelta T cells. Surface molecules attributed to myeloid cells, such as CD14, CD68, and scavenger receptor-1, were identified in both populations. Furthermore, expression of B lymphocyte-induced maturation protein, a master regulator of B cell and myeloid cell differentiation, was identified by SAGE analysis and was confirmed at the RNA level to be selectively expressed in gammadelta T cells vs alphabeta T cells. These results provide new insights into the inherent differences between circulating gammadelta T cell subsets.