Knockin Mice (knockin + mouse)

Distribution by Scientific Domains


Selected Abstracts


Knockin Animal Models of Inherited Arrhythmogenic Diseases: What Have We Learned From Them?

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2007
KATHY M NILLES B.S.
Mouse models are becoming an increasingly accepted method of studying human diseases. Knockin and knockout techniques have several advantages over traditional transgenic overexpression, and the versatility of the knockin mouse allows the study of both gain of function mutations through targeted mutagenesis, as well as the replacement of one gene by another functional gene. Here, we will review the methods available to generate knockin mice; provide an overview of the techniques used to study electrophysiology in the mice at the cellular, organ, and whole animal level; and highlight knockin mice that have implications for inherited arrhythmias. Specifically, we will focus on models that used knockin mice to clarify gene expression, identify similarities and differences between related genes, and model human arrhythmia syndromes. Our goal is to provide the reader with a general understanding of studies done on knockin mouse models of inherited arrhythmias as well as ideas for future directions. [source]


Epigenetic changes play critical role in age-associated dysfunctions of the liver

AGING CELL, Issue 5 2010
Jingling Jin
Summary CCAAT/Enhancer Binding Proteins family proteins are important regulators of liver functions. Here, we show the critical role of C/EBP,-mediated chromatin remodeling in the age-associated dysfunctions of the liver and in the maintenance of physiological homeostasis. Because ph-S193 isoform of C/EBP, is increased in livers of old mice, we have generated C/EBP,-S193D knockin mice, which mimic the ph-S193 isoform of C/EBP,. Analyses of these mice showed that the S193D mutation causes chromatin remodeling leading to histological appearance of ,foci-like' nodules, which are also observed in livers of old mice. These ,foci-like' structures contain K9 trimethylated histone H3, a marker of heterochromatin. The increase of heterochromatin regions in S193D mice correlates with the elevation of S193D-C/EBP,-HDAC1 complexes and with dys-regulation of gene expression including epigenetic silencing of cyclin D1 and D2 promoters and the inhibition of liver proliferation. The elimination of C/EBP,-HDAC1 complexes in S193D mice by inhibition of HDAC1 corrects chromatin structure and normalizes expression of cyclin D1 and D2. We found that epigenetic dys-regulation is also associated with the elevation of C/EBP, and with the increase of C/EBP,/, heterodimers in S193D mice. The C/EBP,/, heterodimers activate transcription of Glut4 and increase the levels of Glut4. As the result, S193D livers have accelerated uptake of glucose and accumulation of glycogen in the liver. Thus, this study demonstrates that the phosphorylation of C/EBP, at S193 leads to the appearance of heterochromatin regions, which correlates with the development of age-related dysfunctions of the liver. [source]


Isolated CD39 Expression on CD4+ T Cells Denotes both Regulatory and Memory Populations

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2009
Q. Zhou
Foxp3+ regulatory T cells (Tregs) express both ectoenzymes CD39 and CD73, which in tandem hydrolyze pericellular ATP into adenosine, an immunoinhibitory molecule that contributes to Treg suppressive function. Using Foxp3GFP knockin mice, we noted that the mouse CD4+CD39+ T-cell pool contains two roughly equal size Foxp3+ and Foxp3, populations. While Foxp3+CD39+ cells are CD73bright and are the bone fide Tregs, Foxp3,CD39+ cells do not have suppressive activity and are CD44+CD62L,CD25,CD73dim/,, exhibiting memory cell phenotype. Functionally, CD39 expression on memory and Treg cells confers protection against ATP-induced apoptosis. Compared with Foxp3,CD39, nave T cells, Foxp3,CD39+ cells freshly isolated from non-immunized mice express at rest significantly higher levels of mRNA for T-helper lineage-specific cytokines IFN-, (Th1), IL-4/IL-10 (Th2), IL-17A/F (Th17), as well as pro-inflammatory cytokines, and rapidly secrete these cytokines upon stimulation. Moreover, the presence of Foxp3,CD39+ cells inhibits TGF-, induction of Foxp3 in Foxp3,CD39, cells. Furthermore, when transferred in vivo, Foxp3,CD39+ cells rejected MHC-mismatched skin allografts in a much faster tempo than Foxp3,CD39, cells. Thus, besides Tregs, CD39 is also expressed on pre-existing memory T cells of Th1-, Th2- and Th17-types with heightened alloreactivity. [source]


Minimal aberrant behavioral phenotypes of neuroligin-3 R451C knockin mice

AUTISM RESEARCH, Issue 3 2008
Kathryn K. Chadman
Abstract Neuroligin-3 is a member of the class of cell adhesion proteins that mediate synapse development and have been implicated in autism. Mice with the human R451C mutation (NL3), identical to the point mutation found in two brothers with autism spectrum disorders, were generated and phenotyped in multiple behavioral assays with face validity to the diagnostic symptoms of autism. No differences between NL3 and their wildtype (WT) littermate controls were detected on measures of juvenile reciprocal social interaction, adult social approach, cognitive abilities, and resistance to change in a spatial habit, findings which were replicated in several cohorts of males and females. Physical and procedural abilities were similar across genotypes on measures of general health, sensory abilities, sensorimotor gating, motor functions, and anxiety-related traits. Minor developmental differences were detected between NL3 and WT, including slightly different rates of somatic growth, slower righting reflexes at postnatal days 2,6, faster homing reflexes in females, and less vocalizations on postnatal day 8 in males. Significant differences in NL3 adults included somewhat longer latencies to fall from the rotarod, less vertical activity in the open field, and less acoustic startle to high decibel tones. The humanized R451C mutation in mice did not result in apparent autism-like phenotypes, but produced detectable functional consequences that may be interpreted in terms of physical development and/or reduced sensitivity to stimuli. [source]


Transgenic expression of Cre recombinase from the tyrosine hydroxylase locus

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 2 2004
Jonas Lindeberg
Abstract Catecholaminergic neurons are affected in several neurological and psychiatric diseases. Tyrosine hydroxylase (TH) is the first, rate-limiting enzyme in catecholamine synthesis. We report a knockin mouse expressing Cre-recombinase from the 3,-untranslated region of the endogenous Th gene by means of an internal ribosomal entry sequence (IRES). The resulting Cre expression matches the normal pattern of TH expression, while the pattern and level of TH are not altered in the knockin mouse. Crossings with two different LacZ reporter mice demonstrated Cre-mediated genomic recombination in TH expressing tissues. In addition, LacZ was found in some unexpected cell populations (including oocytes), indicating recombination due to transient developmental TH expression. Our novel knockin mouse can be used for generation of tissue-specific or general knockouts (depending on scheme of crossing) in mice carrying genes flanked by loxP sites. This knockin mouse can also be used for tracing cell lineages expressing TH during development. genesis 40:67,73, 2004. 2004 Wiley-Liss, Inc. [source]


Knockin Animal Models of Inherited Arrhythmogenic Diseases: What Have We Learned From Them?

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2007
KATHY M NILLES B.S.
Mouse models are becoming an increasingly accepted method of studying human diseases. Knockin and knockout techniques have several advantages over traditional transgenic overexpression, and the versatility of the knockin mouse allows the study of both gain of function mutations through targeted mutagenesis, as well as the replacement of one gene by another functional gene. Here, we will review the methods available to generate knockin mice; provide an overview of the techniques used to study electrophysiology in the mice at the cellular, organ, and whole animal level; and highlight knockin mice that have implications for inherited arrhythmias. Specifically, we will focus on models that used knockin mice to clarify gene expression, identify similarities and differences between related genes, and model human arrhythmia syndromes. Our goal is to provide the reader with a general understanding of studies done on knockin mouse models of inherited arrhythmias as well as ideas for future directions. [source]