Use of new biotechnology tools for xenotransplantation

La xénotransplantation est une approche séduisante, tentée à de nombreuses reprises depuis plus d’un siècle, pour subvenir au manque d’organes ou de tissus humains pour les transplantations. Modifier génétiquement les tissus de donneurs de greffon de mammifères d’élevage, en particulier, est une des stratégies mises en œuvre afin de limiter le rejet par l’hôte. Cependant, un nombre considérable de gènes est impliqué dans les mécanismes de rejet. Ainsi, la production d’animaux génétiquement modifiés répondant aux critères nécessaires est très complexe. L’émergence d’outils performants de biotechnologie (comme l’outil CRISPR/Cas9) a redonné un nouveau souffle aux recherches dans ce domaine. Une abondante littérature existe qui fait le point sur les différentes approches et les tentatives en cours ou en prévision, utilisant soit des cellules et des tissus, soit des organes issus de ces animaux génétiquement modifiés.Xenotransplantation is a seductive approach that has been tried many times for over a century in order to circumvent the lack of human organs or tissues for transplantation. Performing genetic alterations in the mammalian organs or tissues is one of the strategies implemented to limit rejection by the hosts. However, a considerable number of genes are involved in the mechanisms of tissue rejection and the production of genetically modified animals meeting the necessary criteria is rather complex. The emergence of powerful biotechnology tools (such as the CRISPR / Cas9 system) has opened new avenues to research in this area. An abundant literature exists which reviews the different approaches and current or planned attempts, using either cells and tissues, or organs from genetically modified animals

A Major Role of the RecFOR Pathway in DNA Double-Strand-Break Repair through ESDSA in Deinococcus radiodurans

In Deinococcus radiodurans, the extreme resistance to DNA–shattering treatments such as ionizing radiation or desiccation is correlated with its ability to reconstruct a functional genome from hundreds of chromosomal fragments. The rapid reconstitution of an intact genome is thought to occur through an extended synthesis-dependent strand annealing process (ESDSA) followed by DNA recombination. Here, we investigated the role of key components of the RecF pathway in ESDSA in this organism naturally devoid of RecB and RecC proteins. We demonstrate that inactivation of RecJ exonuclease results in cell lethality, indicating that this protein plays a key role in genome maintenance. Cells devoid of RecF, RecO, or RecR proteins also display greatly impaired growth and an important lethal sectoring as bacteria devoid of RecA protein. Other aspects of the phenotype of recFOR knock-out mutants paralleled that of a ΔrecA mutant: ΔrecFOR mutants are extremely radiosensitive and show a slow assembly of radiation-induced chromosomal fragments, not accompanied by DNA synthesis, and reduced DNA degradation. Cells devoid of RecQ, the major helicase implicated in repair through the RecF pathway in E. coli, are resistant to γ-irradiation and have a wild-type DNA repair capacity as also shown for cells devoid of the RecD helicase; in contrast, ΔuvrD mutants show a markedly decreased radioresistance, an increased latent period in the kinetics of DNA double-strand-break repair, and a slow rate of fragment assembly correlated with a slow rate of DNA synthesis. Combining RecQ or RecD deficiency with UvrD deficiency did not significantly accentuate the phenotype of ΔuvrD mutants. In conclusion, RecFOR proteins are essential for DNA double-strand-break repair through ESDSA whereas RecJ protein is essential for cell viability and UvrD helicase might be involved in the processing of double stranded DNA ends and/or in the DNA synthesis step of ESDSA

A combination of distal and proximal regions is required for efficient prolactin regulation of transfected rabbit alphaS1-casein chloramphenicol acetyltransferase constructs

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Structure of the gene encoding rabbit às1-casein

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Extracellular matrix regulates alpha S1-casein gene expression in rabbit primary mammary cells and CCAAT enhancer binding protein (C/EBP) binding activity

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A MGF/STAT5 binding site is necessary in the distal enhancer for high prolactin induction of transfected rabbit às1-casein-CAT gene transcription

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Preparation of recombinant proteins in milk to improve human and animal health

Milk is a very abundant source of proteins for animal and human consumption. Milk composition can be modified using transgenesis, including exogenous gene addition and endogenous gene inactivation. The study of milk protein genes has provided researchers with regulatory regions capable of efficiently and specifically driving the expression of foreign genes in milk. The projects underway are aimed at modifying milk composition, improving its nutritional value, reducing mammary infections, providing consumers with antipathogen proteins and preparing purified recombinant proteins for pharmaceutical use. The present paper summarises the current progress in this field

DMRT1 is Required for Fetal Germ Cell Development in Rabbit Ovary

International audienceDMRT1 (doublesex and mab-3 related transcription factor 1) is a conserved transcriptional factor expressed in the genital ridge in both sexes and plays a critical role in mammals, nonmammalian vertebrates and non-vertebrate testis development. A lack of Dmrt1 expression induces Sertoli cell fate reprogramming into Granulosa-like cells and formation of feminized germ cells in the mouse adult testis. Although, most of the female mouse lacking Dmrt1 expression in fetal germ cells are fertile, we discovered that homozygous DMRT1 mutant female rabbits are infertile and have smaller ovaries starting at 28 days post conception (dpc) when germ cell should be proliferating. We showed that DMRT1 expression is enriched in female germ cells and reaches its higher levels of expression between 28 dpc and 4 days postpartum (dpp) which corresponds to the onset of meiosis in the rabbit ovary. Thus, we hypothesize that DMRT1 could play a regulatory role on female germ cells differentiation by controlling expression of meiotic genes. Histological analysis confirmed a disruption of ovarian cells formation specifically marked by a failure of meiosis initiation leading to follicular development arrest and associated with a reduction of DDX4 and STRA8 expression at 28 dpc. These results suggest a potential role of DMRT1 in rabbit ovarian development and provide new insights in the regulatory mechanisms involved in germ cell differentiation. Therefore, to complete our understanding of the mechanisms that underly the effects of DMRT1 in germ cells we are currently performing the transcriptomic analysis of ovaries lacking DMRT1 at birth combined with a DMRT1-ChIP sequencing in order to identify specific targets of DMRT1

Transgenesis for the study and the control of lactation

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