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Vladimir S. Prassolov

Bio: Vladimir S. Prassolov is an academic researcher from Engelhardt Institute of Molecular Biology. The author has contributed to research in topics: RNA interference & Leukemia. The author has an hindex of 21, co-authored 89 publications receiving 1428 citations. Previous affiliations of Vladimir S. Prassolov include National Cancer Research Institute & Russian Academy of Sciences.


Papers
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Journal ArticleDOI
TL;DR: Current ideas on mechanisms used by 40S ribosomal subunits to cope with complex 5′UTRs are modified and called into question the conception that every long GC-rich5′UTR working with a high efficiency has to contain an IRES.
Abstract: Retrotransposon L1 is a mobile genetic element of the LINE family that is extremely widespread in the mammalian genome. It encodes a dicistronic mRNA, which is exceptionally rare among eukaryotic cellular mRNAs. The extremely long and GC-rich L1 5 untranslated region (5UTR) directs synthesis of numerous copies of RNA-binding protein ORF1p per mRNA. One could suggest that the 5UTR of L1 mRNA contained a powerful internal ribosome entry site (IRES) element. Using transfection of cultured cells with the polyadenylated monocistronic (L1 5UTR-Fluc) or bicistronic (Rluc-L1 5UTR-Fluc) RNA constructs, capped or uncapped, it has been firmly established that the 5UTR of L1 does not contain an IRES. Uncapping reduces the initiation activity of the L1 5UTR to that of background. Moreover, the translation is inhibited by upstream AUG codons in the 5UTR. Nevertheless, this cap-dependent initiation activity of the L1 5UTR was unexpectedly high and resembles that of the beta-actin 5UTR (84 nucleotides long). Strikingly, the deletion of up to 80% of the nucleotide sequence of the L1 5UTR, with most of its stem loops, does not significantly change its translation initiation efficiency. These data can modify current ideas on mechanisms used by 40S ribosomal subunits to cope with complex 5UTRs and call into question the conception that every long GC-rich 5UTR working with a high efficiency has to contain an IRES. Our data also demonstrate that the ORF2 translation initiation is not directed by internal initiation, either. It is very inefficient and presumably based on a reinitiation event.

114 citations

Journal ArticleDOI
TL;DR: It is shown that the 216-nt long 5′-UTR of Hsp70 mRNA acts as an IRES that directs ribosomes to the downstream start codon by a cap-independent mechanism, and that the IRES activity requires integrity of almost the entire sequence of the 5′ -UTR.

91 citations

Journal ArticleDOI
TL;DR: Peritumoral administration of IL-2-producing RAT-1 cells into congenitally athymic (nu/nu) mice carrying subcutaneous transplants of human carcinoma cells inhibited the growth of the human tumour xenografts.

90 citations

Journal ArticleDOI
TL;DR: It is not mandatory to invoke the IRES hypothesis, at least for some mRNAs, to explain their preferential translation when eIF4E is partially inactivated, because in cultured cells or cytoplasmic extracts both the level of stimulation with the cap and the overall translation activity do not correlate with the cumulative energy of the secondary structure of the tested 5′ UTRs.
Abstract: Many mammalian mRNAs possess long 5' UTRs with numerous stem-loop structures. For some of them, the presence of Internal Ribosome Entry Sites (IRESes) was suggested to explain their significant activity, especially when cap-dependent translation is compromised. To test this hypothesis, we have compared the translation initiation efficiencies of some cellular 5' UTRs reported to have IRES-activity with those lacking IRES-elements in RNA-transfected cells and cell-free systems. Unlike viral IRESes, the tested 5' UTRs with so-called 'cellular IRESes' demonstrate only background activities when placed in the intercistronic position of dicistronic RNAs. In contrast, they are very active in the monocistronic context and the cap is indispensable for their activities. Surprisingly, in cultured cells or cytoplasmic extracts both the level of stimulation with the cap and the overall translation activity do not correlate with the cumulative energy of the secondary structure of the tested 5' UTRs. The cap positive effect is still observed under profound inhibition of translation with eIF4E-BP1 but its magnitude varies for individual 5' UTRs irrespective of the cumulative energy of their secondary structures. Thus, it is not mandatory to invoke the IRES hypothesis, at least for some mRNAs, to explain their preferential translation when eIF4E is partially inactivated.

83 citations

Journal ArticleDOI
TL;DR: The gene expression database of normal human tissues based on uniformly screened original sequencing data was constructed and deposited, finding that overall 463 biosamples showed tissue-specific rather than platform- or database-specific clustering and could be aggregated in a single database termed Oncobox Atlas of Normal Tissue Expression (ANTE).
Abstract: Comprehensive analysis of molecular pathology requires a collection of reference samples representing normal tissues from healthy donors. For the available limited collections of normal tissues from postmortal donors, there is a problem of data incompatibility, as different datasets generated using different experimental platforms often cannot be merged in a single panel. Here, we constructed and deposited the gene expression database of normal human tissues based on uniformly screened original sequencing data. In total, 142 solid tissue samples representing 20 organs were taken from post-mortal human healthy donors of different age killed in road accidents no later than 36 hours after death. Blood samples were taken from 17 healthy volunteers. We then compared them with the 758 transcriptomic profiles taken from the other databases. We found that overall 463 biosamples showed tissue-specific rather than platform- or database-specific clustering and could be aggregated in a single database termed Oncobox Atlas of Normal Tissue Expression (ANTE). Our data will be useful to all those working with the analysis of human gene expression. Machine-accessible metadata file describing the reported data (ISA-Tab format)

65 citations


Cited by
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Journal ArticleDOI
TL;DR: Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.
Abstract: Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.

1,665 citations

01 Jan 2010
TL;DR: It is found that women over 50 are more likely to have a family history of diabetes, especially if they are obese, than women under the age of 50.
Abstract: Hypertension 66 (20.3%) 24 (24.2%) 30 (16.3%) NS Diabetes 20 (6.2%) 7 (7.1%) 10 (5.4%) NS Excess weight 78 (24%) 27 (27.3%) 44 (23.9%) NS Smokers 64 (19.7%) 17 (17.2%) 35 (19.0%) NS Age >50 years 137 (42.2%) 54 (54.5%) 67 (36.4%) <0.02 Kidney disease 7 (2.2%) 1 (1%) 5 (2.7%) NS Family history, DM 102 (31.4%) 28 (28.3%) 66 (35.9%) NS

1,369 citations

Journal ArticleDOI
TL;DR: Although both self-assemble in response to stress-induced perturbations in translation, several recent reports reveal novel proteins and RNAs that are components of these structures but also perform other cellular functions.

1,024 citations

Journal ArticleDOI
Jun Zhou1, Ji Wan1, Xiangwei Gao1, Xingqian Zhang1, Samie R. Jaffrey1, Shu-Bing Qian1 
22 Oct 2015-Nature
TL;DR: The elucidation of the dynamic features of 5′UTR methylation and its critical role in cap-independent translation not only expands the breadth of physiological roles of m6A, but also uncovers a previously unappreciated translational control mechanism in heat shock response.
Abstract: The most abundant mRNA post-transcriptional modification is N(6)-methyladenosine (m(6)A), which has broad roles in RNA biology. In mammalian cells, the asymmetric distribution of m(6)A along mRNAs results in relatively less methylation in the 5' untranslated region (5'UTR) compared to other regions. However, whether and how 5'UTR methylation is regulated is poorly understood. Despite the crucial role of the 5'UTR in translation initiation, very little is known about whether m(6)A modification influences mRNA translation. Here we show that in response to heat shock stress, certain adenosines within the 5'UTR of newly transcribed mRNAs are preferentially methylated. We find that the dynamic 5'UTR methylation is a result of stress-induced nuclear localization of YTHDF2, a well-characterized m(6)A 'reader'. Upon heat shock stress, the nuclear YTHDF2 preserves 5'UTR methylation of stress-induced transcripts by limiting the m(6)A 'eraser' FTO from demethylation. Remarkably, the increased 5'UTR methylation in the form of m(6)A promotes cap-independent translation initiation, providing a mechanism for selective mRNA translation under heat shock stress. Using Hsp70 mRNA as an example, we demonstrate that a single m(6)A modification site in the 5'UTR enables translation initiation independent of the 5' end N(7)-methylguanosine cap. The elucidation of the dynamic features of 5'UTR methylation and its critical role in cap-independent translation not only expands the breadth of physiological roles of m(6)A, but also uncovers a previously unappreciated translational control mechanism in heat shock response.

904 citations

Journal ArticleDOI
TL;DR: A wide range of new lead finding and lead optimization opportunities result from novel screening methods by NMR, which are the topic of this review article.
Abstract: In recent years, tools for the development of new drugs have been dramatically improved. These include genomic and proteomic research, numerous biophysical methods, combinatorial chemistry and screening technologies. In addition, early ADMET studies are employed in order to significantly reduce the failure rate in the development of drug candidates. As a consequence, the lead finding, lead optimization and development process has gained marked enhancement in speed and efficiency. In parallel to this development, major pharma companies are increasingly outsourcing many components of drug discovery research to biotech companies. All these measures are designed to address the need for a faster time to market. New screening methodologies have contributed significantly to the efficiency of the drug discovery process. The conventional screening of single compounds or compound libraries has been dramatically accelerated by high throughput screening methods. In addition, in silico screening methods allow the evaluation of virtual compounds. A wide range of new lead finding and lead optimization opportunities result from novel screening methods by NMR, which are the topic of this review article.

803 citations