Loss of function of DJ‐1 (PARK7) is associated with autosomal recessive early‐onset Parkinson's disease (PD), one of the major age‐related neurological diseases. In this study, we extended former ...studies on DJ‐1 knockout mice by identifying subtle morphological and behavioural phenotypes. The DJ‐1 gene trap‐induced null mutants exhibit less dopamine‐producing neurons in the ventral tegmental area (VTA). They also exhibit slight changes in behaviour, i.e. diminished rearing behaviour and impairments in object recognition. Furthermore, we detected subtle phenotypes, which suggest that these animals compensate for the loss of DJ‐1. First, we found a significant upregulation of mitochondrial respiratory enzyme activities, a mechanism known to protect against oxidative stress. Second, a close to significant increase in c‐Jun N‐terminal kinase 1 phosphorylation in old DJ‐1‐deficient mice hints at a differential activation of neuronal cell survival pathways. Third, as no change in the density of tyrosine hydroxylase (TH)‐positive terminals in the striatum was observed, the remaining dopamine‐producing neurons likely compensate by increasing axonal sprouting. In summary, the present data suggest that DJ‐1 is implicated in major non‐motor symptoms of PD appearing in the early phases of the disease—such as subtle impairments in motivated behaviour and cognition—and that under basal conditions the loss of DJ‐1 is compensated
The hallmark of Parkinson's disease (PD) is the selective loss of dopamine neurons in the ventral midbrain. Although the cause of neurodegeneration in PD is unknown, a Mendelian inheritance pattern ...is observed in rare cases, indicating a genetic factor. Furthermore, pathological analyses of PD substantia nigra have correlated cellular oxidative stress and altered proteasomal function with PD. Homozygous mutations in DJ-1 were recently described in two families with autosomal recessive Parkinsonism, one of which is a large deletion that is likely to lead to loss of function. Here we show that embryonic stem cells deficient in DJ-1 display increased sensitivity to oxidative stress and proteasomal inhibition. The accumulation of reactive oxygen species in toxin-treated DJ-1-deficient cells initially appears normal, but these cells are unable to cope with the consequent damage that ultimately leads to apoptotic death. Furthermore, we find that dopamine neurons derived from in vitro-differentiated DJ-1-deficient embryonic stem cells display decreased survival and increased sensitivity to oxidative stress. These data are consistent with a protective role for DJ-1, and demonstrate the utility of genetically modified embryonic stem cell-derived neurons as cellular models of neuronal disorders.
Here we describe a detailed analysis of the expression of neurochondrin ( ncdn) in the developing and adult mouse brain. Ncdn is first expressed in the hindbrain and spinal cord at embryonic day 10.5 ...(E10.5) followed by expression in the midbrain at E11.5. By E18 ncdn is also expressed in the diencephalon and telencephalon. However, strongest expression is still observed in the hindbrain. In adults, the expression in the forebrain is as strong as in the hindbrain. Ncdn is highly expressed in the hippocampus, piriform cortex, septum, amygdaloid complex, medial geniculate nucleus, inferior colliculus, cerebellar nuclei and the nuclei of the Vth, VIIth, and XIIth cranial nerves.
A type of retroviral gene trap vectors has been developed that can induce conditional mutations in most genes expressed in mouse embryonic stem (ES) cells. The vectors rely on directional ...site-specific recombination systems that can repair and reinduce gene trap mutations when activated in succession. After the gene traps are inserted into the mouse genome, genetic mutations can be produced at a particular time and place in somatic cells. In addition to their conditional features, the vectors create multipurpose alleles amenable to a wide range of postinsertional modifications. Here we have used these directional recombination vectors to assemble the largest library of ES cell lines with conditional mutations in single genes yet assembled, presently totaling 1,000 unique genes. The trapped ES cell lines, which can be ordered from the German Gene Trap Consortium, are freely available to the scientific community.
Four homologs to the Drosophila homeotic gene spalt ( sal ) exist in both humans and mice ( SALL1 to SALL4 / Sall1 to Sall4 , respectively). Mutations in both SALL1 and SALL4 result in the ...autosomal-dominant developmental disorders Townes-Brocks and Okihiro syndrome, respectively. In contrast, no human diseases have been associated with SALL2 to date, and Sall2 -deficient mice have shown no apparent abnormal phenotype. We generated mice deficient in Sall2 and, contrary to previous reports, 11% of our Sall2 -deficient mice showed background-specific neural tube defects, suggesting that Sall2 has a role in neurogenesis. To investigate whether Sall4 may compensate for the absence of Sall2 , we generated compound Sall2 knockout/ Sall4 genetrap mutant mice. In these mutants, the incidence of neural tube defects was significantly increased. Furthermore, we found a similar phenotype in compound Sall1/4 mutant mice, and in vitro studies showed that SALL1, SALL2, and SALL4 all co-localized in the nucleus. We therefore suggest a fundamental and redundant function of the Sall proteins in murine neurulation, with the heterozygous loss of a particular SALL protein also possibly compensated in humans during development.
Fibroblast growth factor-6 (FGF-6) belongs to a family of cytokines that control cell proliferation, cell differentiation, and morphogenetic events. Individual FGFs are either expressed widely or in ...a restricted pattern during embryonic, fetal, and adult life. FGF-6 exhibits a restricted expression profile predominantly in the myogenic lineage. Important functions in wound healing and tissue regeneration have been proposed for various FGFs in the past, although data from knockout mice have not supported this view. We have inactivated the FGF-6 gene in mice to investigate the role of FGF-6 in skeletal muscle development and regeneration. Wild-type mice up-regulate FGF-6 after skeletal muscle injuries and completely restore experimentally damaged skeletal muscle. In contrast, FGF-6(-/-) mutant mice show a severe regeneration defect with fibrosis and myotube degeneration. The number of MyoD- and Myogenin-expressing activated satellite cells after injury were significantly reduced in mutants. This reduction was not caused by a reduced pool of quiescent satellite cells but presumably by a lack of activation or proliferation. Interbreeding of FGF-6(-/-) mutants with mdx mice leads to striking dystrophic changes in skeletal muscles of double homozygous mice characterized by myotube degeneration, the presence of large amounts of mononuclear cells, and deposition of collagen. RNA analysis revealed an up-regulation of MyoD mRNA in mdx but not in FGF-6(-/-)/mdx double mutant mice. We conclude that FGF-6 is a critical component of the muscle regeneration machinery in mammals, possibly by stimulating or activating satellite cells.
The molecular mechanisms maintaining glomerular filtration barrier are under intensive study. This study describes a mutant Nphs1 mouse line generated by gene-trapping. Nephrin, encoded by Nphs1, is ...a structural protein of interpodocyte filtration slits crucial for formation of primary urine. Nephrin(trap/trap) mutants show characteristic features of proteinuric disease and die soon after birth. Morphologically, fibrotic glomeruli with distorted structures and cystic tubular lesions were observed, but no prominent changes in the branching morphogenesis of the developing collecting ducts could be found. Western blotting and immunohistochemical analyses confirmed the absence of nephrin in nephrin(trap/trap) glomeruli. The immunohistochemical staining showed also that the interaction partner of nephrin, CD2-associated protein (CD2AP), and the slit-diaphragm-associated protein, ZO-1alpha (-), appeared unchanged, whereas the major anionic apical membrane protein of podocytes, podocalyxin, somewhat punctate as compared with the wild-type (wt) and nephrin(wt/trap) stainings. Electron microscopy revealed that >90% of the podocyte foot processes were fused. The remaining interpodocyte junctions lacked slit diaphragms and, instead, showed tight adhering areas. In the heterozygote glomeruli, approximately one third of the foot processes were fused and real-time RT-PCR showed >60% decrease of nephrin-specific transcripts. These results show an effective nephrin gene elimination, resulting in a phenotype that resembles human congenital nephrotic syndrome. Although the nephrin(trap/trap) mice can be used to study the pathophysiology of the disease, the heterozygous mice may provide a useful model to study the gene dose effect of this crucial protein of the glomerular filtration barrier.
Targeted Mutagenesis, Mouse Floss, T.; Guimera, J.
Brenner's Encyclopedia of Genetics,
2013, 20130000, Letnik:
7
Reference, Book Chapter
Genome-wide association screens (GWASs) for a large number of human genetic diseases generate novel hypotheses about familial and sporadic mutations. Gene targeting in embryonic stem cell (ESC), ...along with the new repertoire of zinc-finger nucleases (ZFNs), TAL effector nucleases (TALENs) and recombinase-mediated cassette exchange (RMCE) techniques, the increasing number of null, point, conditional, large deletions, inducible, reporter, hypomorphic alleles, combined with additional breeding schemes, different mutant backgrounds and several reporter lines, represent a vast repertoire of molecular tools that provides everything needed to target essentially any gene of interest in virtually any cell type, making imagination the only limiting factor. These techniques will allow us to investigate novel hypotheses in model organisms, which are no longer limited to the mouse. Correction of inherited mutations in adult human stem cells and even zygotes may be done with great efficiency in the future.
Genetics Nomenclature, Mouse Guimera, J.; Floss, T.
Brenner's Encyclopedia of Genetics,
2013, 20130000, Letnik:
3
Reference, Book Chapter
The matchless identification of mouse genes or genetic locus is critical in research and in literature to avoid misleading. With this notion in mind, the Mouse Genome and Nomenclature Committee is ...carrying out the implementation of the mouse nomenclature rules and guidelines. The major aim is to assign unique identifiers to each gene (structural, mitochondrial, nuclear tRNA and rRNA genes); genetic locus (ESTs, mapped genomic DNA fragments, microRNAs, and DNA variants); and chromosomal anomalies and mutations (mutant phenotypes, allelic variations, gene-trap loci, SNPs, and spontaneous and induced mutations). A background in the field and potential controversy are discussed; a summary of the rules and guidelines are given with examples as well.
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