Pierre Tiollais

Bio: Pierre Tiollais is an academic researcher from Pasteur Institute. The author has contributed to research in topics: Hepatitis B virus & Virus. The author has an hindex of 72, co-authored 258 publications receiving 21443 citations. Previous affiliations of Pierre Tiollais include Saint Louis University & Laboratory of Molecular Biology.

The hepatitis B virus

Abstract: DNA recombinant technology has radically changed hepatitis B virus (HBV) virology. The genetic organization, transcription and replication of the virus are basically understood, structures of integrated HBV sequences in hepatocellular carcinoma have been characterized, and new vaccines produced by recombinant DNA technique are being developed.

Identification of a retinoic acid responsive element in the retinoic acid receptor & beta;gene

Abstract: Retinoic acid, the first morphogen described so far in vertebrates, is a vitamin A derivative which exerts striking effects on development and differentiation. The identification of three retinoic acid receptors as members of the nuclear receptor super-family provides an explantation for the molecular action of morphogens on gene expression. Functional analysis of the receptors requires the identification of target genes and of their cis-acting retinoic acid-responsive elements. We have previously shown that the retinoic acid receptor beta gene is transcriptionally up-regulated by retinoic acid and now report the characterization of a functional retinoic acid responsive element in the beta gene that mediates trans-activation by retinoic acid. Using deletion mapping, we have identified a 27-base pair fragment, located 59 base pairs upstream of the transcriptional start, which confers retinoic acid responsiveness on the herpes virus thymidine kinase promoter. This sequence contains a perfect direct repeat of the motif GTTCAC, which is reminiscent of the 5' half-palindrome of the thyroid and oestrogen hormone responsive elements. Specific binding of the beta protein to the retinoic acid responsive element is demonstrated and is independent of the presence of retinoic acid. Both alpha and beta receptors enhance retinoic acid response in CV1 cells, indicating that they can both act through the same DNA sequence.

Identification of a second human retinoic acid receptor

Abstract: We have previously described a human complementary DNA that encodes a novel protein which is homologous to members of the steroid/thyroid nuclear receptor multigene family. This novel protein (hap for hepatoma) exhibits strong homology with the human retinoic acid receptor (RAR) which has been recently characterized. To test the possibility that the hap protein might also be a retinoid receptor, a chimaeric receptor was created by replacing the putative DNA binding domain of hap with that of the human oestrogen receptor (ER). The resulting hap-ER chimaera was then tested for its ability to trans-activate an oestrogen-responsive reporter gene (vit-tk-CAT) in the presence of possible receptor ligands. Here we show that retinoic acid (RA) at physiological concentrations is effective in inducing the expression of this reporter gene by the hap-ER chimaeric receptor. This demonstrates the existence of two human retinoic acid receptors designated RAR-alpha and RAR-beta.

Nucleotide sequence of the hepatitis B virus genome (subtype ayw) cloned in E. coli.

Abstract: The complete nucleotide sequence of hepatitis B virus genome (subtype ayw) cloned in Escherichia coli has been determined using the Maxam and Gilbert method and the dideoxynucleotide method. This sequence is 3,182 nucleotides long. Location of the nonsense codons shows that the coding capacity of the L chain is larger than the coding capacity of the Schain. Eight open regions, able to code for polypeptide chains larger than 100 amino acids, have been located. Region 6, which is the largest, covers more than 80% of the genome. The gene S which codes for polypeptide I of the Hbs Ag and was previously located between coordinates 95.1 and 73.6 is contained in region 7.

The steroid and thyroid hormone receptor superfamily

Abstract: Analyses of steroid receptors are important for understanding molecular details of transcriptional control, as well as providing insight as to how an individual transacting factor contributes to cell identity and function. These studies have led to the identification of a superfamily of regulatory proteins that include receptors for thyroid hormone and the vertebrate morphogen retinoic acid. Although animals employ complex and often distinct ways to control their physiology and development, the discovery of receptor-related molecules in a wide range of species suggests that mechanisms underlying morphogenesis and homeostasis may be more ubiquitous than previously expected.

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

Construction and characterization of amplifiable multicopy DNA cloning vehicles derived from the P15A cryptic miniplasmid.

Abstract: Construction and characterization of a class of multicopy plasmid cloning vehicles containing the replication system of miniplasmid P15A are described. The constructed plasmids have cleavage sites within antibiotic resistance genes for a variety of commonly employed site-specific endonucleases, permitting convenient use of the insertional inactivation procedure for the selection of clones that contain hybrid DNA molecules. Although the constructed plasmids showed DNA sequence homology with the ColE1 plasmid within the replication region, were amplifiable by chloramphenicol or spectinomycin, required DNA polymerase I for replication, and shared other replication properties with ColE1, they were nevertheless compatible with ColE1. P15A-derived plasmids were not self-transmissible and were mobilized poorly by Hfr strains; however, mobilization was complemented by the presence of a ColE1 plasmid within the same cell.