Phosphorylation of the retinoic acid receptor RARγ2 is crucial for the neuronal differentiation of mouse embryonic stem cells.

Retinoic acid (RA) plays key roles in cell differentiation and growth arrest by activating nuclear RA receptors (RARs) (α, β and γ), which are ligand-dependent transcription factors. RARs are also phosphorylated in response to RA. Here, we investigated the in vivo relevance of the phosphorylation of RARs during RA-induced neuronal differentiation of mouse embryonic stem cells (mESCs).

Mouse testis development and function are differently regulated by follicle-stimulating hormone receptors signaling during fetal and prepubertal life.

It is currently admitted that Follicle-Stimulating Hormone (FSH) is physiologically involved in the development and function of fetal/neonatal Sertoli cells in the rat but not the mouse. However, FSH is produced by both species from late fetal life onwards. We thus reinvestigated the role of FSH in mouse testis development at day 0 (birth) 6, 8 and 10 post-partum (dpp) by using mice that lack functional FSH receptors (FSH-R(-/-)).

Highly-efficient, fluorescent, locus directed cre and FlpO deleter mice on a pure C57BL/6N genetic background.

To facilitate the use of the new mutant resource developed in the mouse, we have generated Cre and FlpO deleter mice on a pure inbred C57BL/6N background. The new transgenic constructs were designed to drive either the Cre or FlpO recombinase, fused to a specific fluorescent marker, respectively the eGFP or the eYFP, and were inserted by homologous recombination in the neutral Rosa26 locus. They allow a rapid, cost-effective, and efficient identification of the carrier individuals through the coexpression of the fluorescent marker.

Helios deficiency has minimal impact on T cell development and function.

Helios is a member of the Ikaros family of zinc finger transcription factors. It is expressed mainly in T cells, where it associates with Ikaros-containing complexes and has been proposed to act as a rate-limiting factor for Ikaros function. Overexpression of wild-type or dominant-negative Helios isoforms profoundly alters alphabeta T cell differentiation and activation, and endogenous Helios is expressed at strikingly high levels in regulatory T cells.

Prokineticin receptor-1 induces neovascularization and epicardial-derived progenitor cell differentiation.

Objective: Identification of novel factors that contribute to myocardial repair and collateral vessel growth hold promise for treatment of heart diseases. We have shown that transient prokineticin receptor-1 (PKR1) gene transfer protects the heart against myocardial infarction in a mouse model. Here, we investigated the role of excessive PKR1 signaling in heart.

Uses of forward and reverse genetics in mice to study gene function.

As the focus of human genetics shifts from Mendelian traits to complex diseases, a sophisticated genetic tool kit-with space for genetics (classical, molecular, statistical, and quantitative), metabolics, proteomics, bioinformatics, and mathematics-is required to elucidate their multifactorial traits and regulatory processes. Importantly, mouse resources optimized to study the actions of isolated genetic loci on a fixed background are insufficient on their own for studying intact polygenic networks and genetic interactions, and researchers must work in the context of experimental model systems that optimally mimic the genetic structure of human populations. The success of such phenogenomic approaches depend on the efficacy by which specific mutations (gene targeting) and variability (recombinant inbreeding) can be introduced into the mouse genome, and on the optimization of phenotyping analyses of the mutant mouse lines.

Knock-in mice reveal nonsense-mediated mRNA decay in the brain.

Nonsense-mediated mRNA decay (NMD) is a process of mRNA surveillance that degrades transcripts harboring a premature termination codon (PTC). Mammalian NMD was mostly studied in cultured cells so far and there was no direct evidence yet that NMD could operate in the brain. We introduced, by homologous recombination in mouse, a PTC in the mu opioid receptor gene (mor).

Rescue of morphogenetic defects and of retinoic acid signaling in retinaldehyde dehydrogenase 2 (Raldh2) mouse mutants by chimerism with wild-type cells.

Retinoic acid (RA), the active vitamin A derivative, is an important developmental signaling molecule in vertebrates. In this study, we have assessed whether minimal numbers and/or specific distributions of RA-producing cells can support normal mouse embryonic development. Retinaldehyde dehydrogenase 2 (RALDH2) is the main RA-synthesizing enzyme acting during development.

A mutation of spastin is responsible for swellings and impairment of transport in a region of axon characterized by changes in microtubule composition.

Mutations of the spastin gene (Sp) are responsible for the most frequent autosomal dominant form of spastic paraplegia, a disease characterized by the degeneration of corticospinal tracts. We show that a deletion in the mouse Sp gene, generating a premature stop codon, is responsible for progressive axonal degeneration, restricted to the central nervous system, leading to a late and mild motor defect. The degenerative process is characterized by focal axonal swellings, associated with abnormal accumulation of organelles and cytoskeletal components.

Knockin mice expressing fluorescent delta-opioid receptors uncover G protein-coupled receptor dynamics in vivo.

The combination of fluorescent genetically encoded proteins with mouse engineering provides a fascinating means to study dynamic biological processes in mammals. At present, green fluorescent protein (GFP) mice were mainly developed to study gene expression patterns or cell morphology and migration. Here we used enhanced GFP (EGFP) to achieve functional imaging of a G protein-coupled receptor (GPCR) in vivo.

A mouse model for human short-stature syndromes identifies Shox2 as an upstream regulator of Runx2 during long-bone development.

Deficiencies or mutations in the human pseudoautosomal SHOX gene are associated with a series of short-stature conditions, including Turner syndrome, Leri-Weill dyschondrosteosis, and Langer mesomelic dysplasia. Although this gene is absent from the mouse genome, the closely related paralogous gene Shox2 displays a similar expression pattern in developing limbs. Here, we report that the conditional inactivation of Shox2 in developing appendages leads to a strong phenotype, similar to the human conditions, although it affects a different proximodistal limb segment.

Conditional (loxP-flanked) allele for the gene encoding the retinoic acid-synthesizing enzyme retinaldehyde dehydrogenase 2 (RALDH2).

Retinoic acid, the active vitamin A derivative, has pleiotropic functions during vertebrate development and postnatal life. Retinaldehyde dehydrogenase 2 (RALDH2) acts as the main retinoic acid-synthesizing enzyme during development. Mouse Raldh2 germline null mutants are early embryonic lethal and exhibit complex abnormalities that include defective heart looping morphogenesis.

Synergistic activity of Sef and Sprouty proteins in regulating the expression of Gbx2 in the mid-hindbrain region.

Sef and Sprouty proteins function as feedback antagonists of fibroblast growth factor (Fgf) signaling in zebrafish embryos. To study the role of Sef in mice, we generated Sef homozygous mutant animals. These animals are viable and show normal expression of mid-hindbrain genes at embryonic days 8.

Knockout mouse models in pain research.

Gene targeting in mice by homologous recombination is a powerful approach to study the role of specific genes in vivo. This technology is now applied to pain-related genes to understand molecular mechanisms of nociceptive behaviors. In this chapter, we provide detailed methodological information for the construction of knockout animals, exemplified by the generation of mice lacking opioid receptor genes.

PU.1 determines the self-renewal capacity of erythroid progenitor cells.

PU.1 is a hematopoietic-specific transcriptional activator that is absolutely required for the differentiation of B lymphocytes and myeloid-lineage cells. Although PU.

Compensation by the muscle limits the metabolic consequences of lipodystrophy in PPAR gamma hypomorphic mice.

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor, which controls adipocyte differentiation. We targeted with homologous recombination the PPAR gamma 2-specific exon B, resulting in a white adipose tissue knockdown of PPAR gamma. Although homozygous (PPAR gamma hyp/hyp) mice are born with similar weight as the WT mice, the PPAR gamma hyp/hyp animals become growth retarded and develop severe lipodystrophy and hyperlipidemia.

Myelin/oligodendrocyte glycoprotein-deficient (MOG-deficient) mice reveal lack of immune tolerance to MOG in wild-type mice.

We studied the immunological basis for the very potent encephalitogenicity of myelin/oligodendrocyte glycoprotein (MOG), a minor component of myelin in the CNS that is widely used to induce experimental autoimmune encephalomyelitis (EAE). For this purpose, we generated a mutant mouse lacking a functional mog gene. This MOG-deficient mouse presents no clinical or histological abnormalities, permitting us to directly assess the role of MOG as a target autoantigen in EAE.

Functional interaction between PARP-1 and PARP-2 in chromosome stability and embryonic development in mouse.

The DNA damage-dependent poly(ADP-ribose) polymerases, PARP-1 and PARP-2, homo- and heterodimerize and are both involved in the base excision repair (BER) pathway. Here, we report that mice carrying a targeted disruption of the PARP-2 gene are sensitive to ionizing radiation. Following alkylating agent treatment, parp-2(-/-)-derived mouse embryonic fibroblasts exhibit increased post-replicative genomic instability, G(2)/M accumulation and chromosome mis-segregation accompanying kinetochore defects.

Projection of an immunological self shadow within the thymus by the aire protein.

Humans expressing a defective form of the transcription factor AIRE (autoimmune regulator) develop multiorgan autoimmune disease. We used aire- deficient mice to test the hypothesis that this transcription factor regulates autoimmunity by promoting the ectopic expression of peripheral tissue- restricted antigens in medullary epithelial cells of the thymus. This hypothesis proved correct.

The function of TIF2/GRIP1 in mouse reproduction is distinct from those of SRC-1 and p/CIP.

Human TIF2 (hTIF2) is a member of the p160 family of nuclear receptor coactivators, which includes SRC-1 and p/CIP. Although the functions of hTIF2 and of its mouse homolog (GRIP1 or mTIF2) have been clearly established in vitro, their physiological role remains elusive. Here, we have generated mice lacking mTIF2/GRIP1 and examined their phenotype with a particular emphasis on reproductive functions.

Impaired neural tube closure, axial skeleton malformations, and tracheal ring disruption in TRAF4-deficient mice.

TRAF4 belongs to the tumor necrosis factor receptor-associated factor (TRAF) family of proteins but, unlike other family members, has not yet been clearly associated to any specific receptor or signaling pathway. To investigate the biological function of TRAF4, we have generated traf4-deficient mice by gene disruption. The traf4 gene mutation is embryonic lethal but with great individual variation, as approximately one third of the homozygous mutant embryos died in utero around embryonic day 14, whereas the others reach adulthood.

Ikaros is critical for B cell differentiation and function.

The Ikaros gene encodes a zinc-finger transcription factor required during early B cell development, as B-lineage cells are absent in mice lacking Ikaros. Here we describe a novel Ikaros-targeted mouse line carrying a beta-galactosidase reporter in which low amounts of Ikaros proteins remain expressed. In homozygote animals, B cells are absent during fetal development, but develop postnatally from a reduced pool of precursors.