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Two-dimensional gel electrophoresis of protein fractions isolated from35 S-radiolabeled cells provides qualitative information on intracellular amounts, 35 S incorporation rates, protein modifications, and subcellular localizations of up to thousands of individual proteins. In this study we extended proteome profiling to provide quantitative data on synthesis rates of individual proteins. We combined fluorescence detection of radiolabeled proteins with SYPRO ruby™ staining and subsequent autoradiography of the same gels, thereby quantifying protein amounts and 35 S incorporation. To calibrate calculation of absolute synthesis rates, we determined the amount and autoradiograph intensity of radiolabeled haptoglobin secreted by interleukin-6 pretreated HepG2 cells. This allowed us to obtain a standard calibration value for 35 S incorporation per autoradiograph intensity unit. This value was used to measure protein synthesis rates during time course experiments of heat-shocked U937 cells. We measured the increasing amounts of hsp70 and calculated it by integration of the determined hsp70 synthesis rates over time. Similar results were obtained by both methods, validating our standardization procedure. Based on the assumption that the synthesis rate of proteins in a steady state of cell metabolism would essentially compensate protein degradation, we calculated biological half-lives of proteins from protein amounts and synthesis rates determined from two-dimensional gels. Calculated protein half-lives were found close to those determined by pulse-chase experiments, thus validating this new method. In conclusion, we devised a method to assess quantitative proteome profiles covering determination of individual amounts, synthesis, and turnover rates of proteins.Molecular & Cellular Proteomics 1: 528 -537, 2002.The ability to monitor variations at the transcriptional and translational levels using DNA microarrays and proteomics is essential to improve our understanding of physiologically relevant processes at a molecular level (1). Current DNA array technologies allow quantitative high throughput analysis of many thousands genes simultaneously. Yet, this analysis is rather confined to steady state mRNA levels, and mRNA abundance does not necessarily reflect the levels of corresponding proteins (2, 3). Protein levels are regulated by posttranscriptional mechanisms including transcript localization (4) and stability (5), translational regulation (6, 7), and protein degradation (8). Therefore, methods to simultaneously determine levels and turnover of the cellular proteins remain an urgent necessity. However, current proteome techniques still lag behind in quantitative high throughput analysis as compared with DNA arrays.A variety of methods have been developed to quantitatively monitor the protein expression profile of cells. Although protein chips and encoded particle-based solution arrays are particularly encouraging as the next generation proteomics platforms (9, 10), current techniques still largely rely on separation o...

Summary Background We used the RNActive® technology platform (CureVac N.V., Tübingen, Germany) to prepare CVnCoV, a COVID-19 vaccine containing sequence-optimized mRNA coding for a stabilized form of SARS-CoV‑2 spike (S) protein encapsulated in lipid nanoparticles (LNP). Methods This is an interim analysis of a dosage escalation phase 1 study in healthy 18–60-year-old volunteers in Hannover, Munich and Tübingen, Germany, and Ghent, Belgium. After giving 2 intramuscular doses of CVnCoV or placebo 28 days apart we assessed solicited local and systemic adverse events (AE) for 7 days and unsolicited AEs for 28 days after each vaccination. Immunogenicity was measured as enzyme-linked immunosorbent assay (ELISA) IgG antibodies to SARS-CoV‑2 S‑protein and receptor binding domain (RBD), and SARS-CoV‑2 neutralizing titers (MN50). Results In 245 volunteers who received 2 CVnCoV vaccinations (2 μg, n = 47, 4 μg, n = 48, 6 μg, n = 46, 8 μg, n = 44, 12 μg, n = 28) or placebo (n = 32) there were no vaccine-related serious AEs. Dosage-dependent increases in frequency and severity of solicited systemic AEs, and to a lesser extent local AEs, were mainly mild or moderate and transient in duration. Dosage-dependent increases in IgG antibodies to S‑protein and RBD and MN50 were evident in all groups 2 weeks after the second dose when 100% (23/23) seroconverted to S‑protein or RBD, and 83% (19/23) seroconverted for MN50 in the 12 μg group. Responses to 12 μg were comparable to those observed in convalescent sera from known COVID-19 patients. Conclusion In this study 2 CVnCoV doses were safe, with acceptable reactogenicity and 12 μg dosages elicited levels of immune responses that overlapped those observed in convalescent sera.

The Bcr-Abl oncoprotein plays a major role in the development and progression of chronic myeloid leukemia and is a determinant of chemotherapy resistance occurring during the blast crisis phase of the disease. The aim of this article was to investigate the possibility of combating the resistance to apoptosis caused by Bcr-Abl by inducing an alternative cell death process. As a model of chronic myeloid leukemia, we employed Bcr-Abl-transfected mouse progenitor 32D cells with low and high Bcr-Abl expression levels corresponding to drug-sensitive and drug-resistant cells, respectively. The drug curcumin (diferuloylmethane), a known potent inducer of cell death in many cancer cells, was investigated for efficacy with Bcr-Abl-expressing cells. Curcumin strongly inhibited cell proliferation and affected cell viability by inducing apoptotic symptoms in all tested cells; however, apoptosis was a relatively late event. G 2 -M cell cycle arrest, together with increased mitotic index and cellular and nuclear morphology resembling those described for mitotic catastrophe, was observed and preceded caspase-3 activation and DNA fragmentation. Mitosis-arrested cells displayed abnormal chromatin organization, multipolar chromosome segregation, aberrant cytokinesis, and multinucleated cellsmorphologic changes typical of mitotic catastrophe. We found that the mitotic cell death symptoms correlated with attenuated expression of survivin, a member of the chromosomal passenger complex, and mislocalization of Aurora B, the partner of survivin in the chromosomal passenger complex. Inhibition of survivin expression with small interfering RNA exhibited similar mitotic disturbances, thus implicating survivin as a major, albeit not the only, target for curcumin action.This study shows that curcumin can overcome the broad resistance to cell death caused by expression of Bcr-Abl and suggests that curcumin may be a promising agent for new combination regimens for drug-resistant chronic myeloid leukemia.

Activins are cytokines of the transforming growth factor β family, which plays a central role in the determination of cell fate and the regulation of tissue balance. Family members are composed of two subunits and this dimerization is critical for liganding their cognate receptors and execution of proper functions. In the current study we focused on the localization of activin β A , β B , β C and β E subunits in the adult rat and analyzed the composition of putative activin β dimers. By dissecting tissue distribution of various activins, we found that the liver, in particular the hepatocytes, is the major source for activin β C and β E transcripts, since other tissues almost failed to express these isoforms. In sharp contrast, the emergence of activin β A and β B appeared ubiquitous. Using a highly selective proteome approach, we were able to identify homo-as well as heterodimers of individual activin subunits, indicating a high redundancy of ligand composition. Certainly, this broad potential to homo-and heterodimerize has to be considered in future studies on activin function.

Activins C and E (homodimers of the betaC and betaE subunits), which are almost exclusively expressed in the liver, are members of the transforming growth factor beta (TGFbeta) superfamily of growth factors. We examined their expression in three different hepatoma cell lines and found that, compared with normal liver or primary hepatocytes, human hepatoblastoma (HepG2), human hepatocellular carcinoma (Hep3B) and rat hepatoma (H4IIEC3) cells have either completely lost or drastically reduced the expression of activins C and E. In order to elucidate the biological function of these proteins we transiently transfected HepG2, Hep3B and H4IIEC3 cell lines with rat activin betaC or betaE cDNA to study the consequences of restoring activin expression in hepatoma cells. Transfection with activin betaA, a known inhibitor of hepatic DNA synthesis and inducer of apoptosis, served as a positive control. We found that transfection of the three cell lines with activin betaC or betaE, as well as with activin betaA, reduced the increase in cell number by up to 40% compared with cells transfected with a control plasmid. Co-culture with a CHO cell clone secreting activin C also inhibited HepG2 cell multiplication. Furthermore, the three hepatoma cell lines studied showed an enhanced rate of apoptosis and elevated levels of active caspases in response to activin transfection. These results indicate that activins C and E share the potential to induce apoptosis in liver derived cell lines with activin A and TGFbeta1.

Gene therapy-induced expression of immunostimulatory molecules at tumor cell level may evoke antitumor immune mechanisms by recruiting and enhancing viability of antigen-processing cells and specific tumoricidal lymphocytes. The antitumor efficacy of a plasmid, coding for granulocyte-macrophage colony-stimulating factor (GM-CSF) and the B7-1 costimulatory immune molecule, delivered into growing solid tumors by electroporation was investigated. Murine fibrosarcomas (JBS) growing in Balb/C mice (p100 mm 3 ) were transfected with GM-CSF/B7-1-expressing plasmid. Complete tumor regression occurred in greater than 60% of treated animals. This response was systemic, durable and tumor specific, with all responding animals resistant to repeat tumor challenge. Using a liver metastatic model, effective cure of distal metastases was achieved following treatment of the primary subcutaneous tumor. This treatment strategy could be applicable in the clinical setting for effective elimination of both primary tumors and associated metastatic disease.

The Bcr-Abl oncoprotein plays a major role in the development and progression of chronic myeloid leukemia (CML). Several studies have suggested that the expression levels of Bcr-Abl are elevated at disease progression to blast crisis and that this plays a significant role in the achievement of drug resistance. We have established cell lines expressing low and high levels of Bcr-Abl to study the molecular mechanisms involved in disease progression and drug resistance. It is now known that the endoplasmic reticulum (ER) can play a major role in the regulation of apoptosis. We therefore investigated whether Bcr-Abl expression modulates ER homeostasis and interferes with ER-mediated apoptotic pathways to promote survival. Bcr-Abl-expressing cells exhibit a decreased amount of free releasable calcium in the ER as well as a weaker capacitative calcium entry response, relative to parental cells. This effect is independent of Bcl-2, which is a known modulator of ER calcium homeostasis. The reduction in ER releasable calcium results in inhibition of the ER/mitochondriacoupling process and mitochondrial calcium uptake. This study demonstrates a novel downstream consequence of BcrAbl signaling. The ability to negate calcium-dependent apoptotic signaling is likely to be a major prosurvival mechanism in Bcr IntroductionChronic myeloid leukemia (CML) is a clonal disorder of the hematopoietic system resulting in the excessive accumulation of immature and mature myeloid cells. The hallmark of CML is the presence of the Philadelphia (Ph) chromosome, which is present in more than 95% of cases and harbors the chimeric gene BCR-ABL. The resultant tyrosine kinase, Bcr-Abl, constitutively activates several signal transduction pathways 1,2 and is believed to be the critical determinant in the pathogenesis of CML.CML is a biphasic disease, starting as an indolent chronic phase followed by a much more aggressive and drug-resistant phase called blast crisis. A specific inhibitor of Bcr-Abl tyrosine kinase activity, imatinib (Gleevec, Glivec) has recently been introduced for the treatment of CML. 3,4 Impressive responses have been seen with patients in chronic phase; however, resistance is common in advanced CML. Reported resistance mechanisms are primarily mutations and amplification of the BCR-ABL gene. [5][6][7][8] A number of groups have suggested that the reason blast crisis (BC) CML is multidrug resistant is due to the antiapoptotic properties of the Bcr-Abl oncoprotein. It has already been shown that BCR-ABL can confer drug resistance when it is transfected into other leukemic cell lines. 9 Several clinical and molecular studies have suggested that the expression levels of Bcr-Abl may play a major role in resistance to apoptosis. 10-13 Down-regulation of Bcr-Abl transcript has been shown to increase drug sensitivity in cells derived from CML. 14 Expression of Bcr-Abl at different levels in hematopoietic progenitor cells found that all cells became growth factor independent, but only the high Bcr-Abl-expressing cells were resistant...