Friedreich ataxia (FA) is a neurodegenerative and cardiodegenerative disease resulting from marked frataxin deficiency. The condition is characterized by ataxia with fatal cardiomyopathy, but the ...pathogenic mechanisms are unclear. We investigated the association between gene expression and progressive histopathological and functional changes using the muscle creatine kinase conditional frataxin knockout (KO) mouse; this mouse develops a severe cardiac phenotype that resembles that of FA patients. We examined KO mice from 3 weeks of age, when they are asymptomatic, to 10 weeks of age, when they die of the disease. Positive iron staining was identified in KO mice from 5 weeks of age, with markedly reduced cardiac function from 6 weeks. We identified an early and marked up-regulation of a gene cohort responsible for stress-induced amino acid biosynthesis and observed markedly increased phosphorylation of eukaryotic translation initiation factor 2α (p-eIF2α), an activator of the integrated stress response, in KO mice at 3 weeks of age, relative to wild-type mice. Importantly, the eIF2α-mediated integrated stress response has been previously implicated in heart failure via downstream processes such as autophagy and apoptosis. Indeed, expression of a panel of autophagy and apoptosis markers was enhanced in KO mice. Thus, the pathogenesis of cardiomyopathy in FA correlates with the early and persistent eIF2α phosphorylation, which precedes activation of autophagy and apoptosis.
The largest anthropogenic extinction events during the Holocene occurred on Pacific islands, where thousands of bird populations were lost. Although ancient DNA approaches have become widely used to ...monitor the genetic variability of species through time, few studies have been conducted to identify the potential cryptic loss of genetic and species diversity within Pacific seabird species. Here we used heterochronous sampling of mitochondrial DNA (Cytochrome
b
) in the genus
Pterodroma
from Norfolk Island to quantify potential loss of genetic and species diversity. We particularly focused on the providence petrel
P. solandri
whose main breeding colony (~ 1,000,000 breeding pairs) became extirpated from Norfolk Island following European settlement circa 1800. We sampled subfossil bones consistent with
Pterodroma
spp. from Norfolk Island, and performed genetic comparisons with other populations of
P. solandri
and congeneric species. The majority of subfossil Norfolk Island individuals exhibited the most common mitochondrial haplotype from Lord Howe Island
P. solandri
, suggesting no appreciable loss of genetic variation as a consequence of the Norfolk Island extirpation. Our findings provide an example where a large seabird population was rapidly extirpated by humans without loss of species-level genetic diversity, probably as a consequence of high connectivity with other populations. However, past connectivity was insufficient to prevent the extirpation itself, which has conservation implications for predicting the resilience of threatened seabirds. In contrast, ancient DNA analyses of smaller
Pterodroma
bones from Norfolk Island indicate the loss of a second species, potentially
P. pycrofti
,
P. brevipes
or another closely related, possibly undescribed taxon, from the Tasman Sea.
The Knockout Mouse Project Austin, Christopher P; Battey, James F; Bradley, Allan ...
Nature genetics,
09/2004, Letnik:
36, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Mouse knockout technology provides a powerful means of elucidating gene function in vivo, and a publicly available genome-wide collection of mouse knockouts would be significantly enabling for ...biomedical discovery. To date, published knockouts exist for only about 10% of mouse genes. Furthermore, many of these are limited in utility because they have not been made or phenotyped in standardized ways, and many are not freely available to researchers. It is time to harness new technologies and efficiencies of production to mount a high-throughput international effort to produce and phenotype knockouts for all mouse genes, and place these resources into the public domain.
To assess the contribution of potential central nervous system pathways implicated in the control of appetite regulation and energy metabolism, it is essential to first identify appropriate animal ...models. Melanin-concentrating hormone (MCH), a conserved cyclic neuropeptide implicated in the modulation of food intake, has been shown to bind and activate two G-protein-coupled receptors, called GPR24 and MCHR2, expressed in human brain and other tissues. Here we show that several non-human species (rat, mouse, hamster, guinea pig, and rabbit) do not have functional MCHR2 receptors, or encode a nonfunctional MCHR2 pseudogene while retaining GPR24 expression. We identified three species for further evaluation that express both MCH receptor subtypes. We cloned and functionally characterized dog, ferret, and rhesus GPR24 and MCHR2 in mammalian cells and studied their brain distribution patterns by in situ hybridization. The homology, expression profile, and functional similarity of the receptors in the dog, ferret, and rhesus to that of human support the potential use of these species as preclinical animal models in the development of therapeutic agents for obesity or other MCH-mediated disorders.
The hemoprotein indoleamine 2,3-dioxygenase (IDO) is the first and rate-limiting enzyme in the most significant pathway for mammalian tryptophan metabolism. It has received considerable attention in ...recent years, particularly due to its dual role in immunity and the pathogenesis of many diseases. Reported here are differences and similarities between biochemical behaviour and structural features of recombinant human IDO and recombinant mouse IDO. Significant differences were observed in the conversion of substrates and pH stability. Differences in inhibitor potency and thermal stability were also noted. Secondary structural features were broadly similar but variation between species was apparent, particularly in the α-helix portion of the enzymes. With mouse models substituting for human diseases, the differences between mouse and human IDO must be recognised before applying experimental findings from one system to the next.
Indoleamine-2,3-dioxygenase-1 (IDO1) is a critical immunoregulatory enzyme responsible for the metabolism of tryptophan during inflammation and disease. Based upon a pyranonaphthoquinone framework, ...the first examples of indoleamine-2,3-dioxygenase-1 (IDO1) inhibitors containing a carborane cage are reported. The novel closo-1,2-carboranyl-N-pyranonaphthoquinone derivatives display low μM binding affinity for the human recombinant enzyme, with IC50 values ranging from 0.78 to 1.77 μM.
Characterization of the Human Cysteinyl Leukotriene 2 Receptor Heise, Christopher E.; O'Dowd, Brian F.; Figueroa, David J. ...
Journal of biological chemistry/The Journal of biological chemistry,
09/2000, Letnik:
275, Številka:
39
Journal Article
Recenzirano
Odprti dostop
The contractile and inflammatory actions of the cysteinyl leukotrienes (CysLTs), LTC4, LTD4, and LTE4, are thought to be mediated through at least two distinct but related CysLT G protein-coupled ...receptors. The human CysLT1 receptor has been recently cloned and characterized. We describe here the cloning and characterization of the second cysteinyl leukotriene receptor, CysLT2, a 346-amino acid protein with 38% amino acid identity to the CysLT1 receptor. The recombinant human CysLT2 receptor was expressed in Xenopusoocytes and HEK293T cells and shown to couple to elevation of intracellular calcium when activated by LTC4, LTD4, or LTE4. Analyses of radiolabeled LTD4 binding to the recombinant CysLT2 receptor demonstrated high affinity binding and a rank order of potency for competition of LTC4 = LTD4 ≫ LTE4. In contrast to the dual CysLT1/CysLT2 antagonist, BAY u9773, the CysLT1 receptor-selective antagonists MK-571, montelukast (SingulairTM), zafirlukast (AccolateTM), and pranlukast (OnonTM) exhibited low potency in competition for LTD4 binding and as antagonists of CysLT2receptor signaling. CysLT2 receptor mRNA was detected in lung macrophages and airway smooth muscle, cardiac Purkinje cells, adrenal medulla cells, peripheral blood leukocytes, and brain, and the receptor gene was mapped to chromosome 13q14, a region linked to atopic asthma.
Indoleamine 2,3-dioxygenase (IDO1) and tryptophan 2,3-dioxygenase (TDO) are tryptophan-degrading enzymes that catalyze the first step in tryptophan catabolism via the kynurenine pathway. TDO is ...widely distributed in both eukaryotes and bacteria. In contrast, IDO has been found only in mammals and yeast. In 2007, a third enzyme, indoleamine 2,3-dioxygenase-2 (IDO2), was discovered. IDO2 is found not only in mammals but also in lower vertebrates. Interestingly, the Km value of IDO2 for L-Trp was 500-1000 fold higher than that of IDO1. In this study, we isolated both IDO1 and IDO2 cDNA from a monotreme, the platypus (Ornithorhynchus anatinus), and a marsupial, the gray short-tailed opossum (Monodelphis domestica). We characterized the recombinant proteins and those of other known IDO1/IDO2 in intact cells and a cell-free system. It was found that methylene blue may not be suitable reductant for IDO2, hence resulting in an underestimation of recombinant IDO2 activity. In intact cells, the Km value of IDO2 for L-Trp was estimated to be much higher than that of IDO1 and this high Km value appears to have been conserved during the evolution of IDO2. The protein encoded by the ancestor gene of IDO1 and IDO2 is likely to have had properties more similar to present day IDO2 than to IDO1.
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