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1.
Dis Model Mech ; 2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34477842

RESUMO

Down syndrome (DS), trisomy 21, results in many complex phenotypes including cognitive deficits, heart defects and craniofacial alterations. Phenotypes arise from an extra copy of human chromosome 21 (Hsa21) genes. However, these dosage-sensitive causative genes remain unknown. Animal models enable identification of genes and pathological mechanisms. The Dp1Tyb mouse model of DS has an extra copy of 63% of Hsa21-orthologous mouse genes. In order to establish if this model recapitulates DS phenotypes, we comprehensively phenotyped Dp1Tyb mice using 28 tests of different physiological systems and found that 468 out of 1800 parameters were significantly altered. We show that Dp1Tyb mice have wide-ranging DS-like phenotypes including aberrant erythropoiesis and megakaryopoiesis, reduced bone density, craniofacial changes, altered cardiac function, a pre-diabetic state and deficits in memory, locomotion, hearing and sleep. Thus, Dp1Tyb mice are an excellent model for investigating complex DS phenotype-genotype relationships for this common disorder.

2.
FASEB J ; 35(9): e21802, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34383984

RESUMO

Mutations in transcription factors often exhibit pleiotropic effects related to their complex expression patterns and multiple regulatory targets. One such mutation in the zinc finger homeobox 3 (ZFHX3) transcription factor, short circuit (Sci, Zfhx3Sci/+ ), is associated with significant circadian deficits in mice. However, given evidence of its retinal expression, we set out to establish the effects of the mutation on retinal function using molecular, cellular, behavioral and electrophysiological measures. Immunohistochemistry confirms the expression of ZFHX3 in multiple retinal cell types, including GABAergic amacrine cells and retinal ganglion cells including intrinsically photosensitive retinal ganglion cells (ipRGCs). Zfhx3Sci/+ mutants display reduced light responsiveness in locomotor activity and circadian entrainment, relatively normal electroretinogram and optomotor responses but exhibit an unexpected pupillary reflex phenotype with markedly increased sensitivity. Furthermore, multiple electrode array recordings of Zfhx3Sci/+ retina show an increased sensitivity of ipRGC light responses.


Assuntos
Ritmo Circadiano/fisiologia , Proteínas de Homeodomínio/metabolismo , Retina/metabolismo , Células Amácrinas/metabolismo , Animais , Luz , Locomoção/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estimulação Luminosa/métodos , Células Ganglionares da Retina/metabolismo , Visão Ocular/fisiologia
3.
Curr Protoc Mouse Biol ; 10(3): e81, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32865891

RESUMO

The 24-hr cycle of activity and sleep provides perhaps the most familiar example of circadian rhythms. In mammals, circadian activity rhythms are generated by a master biological clock located in the hypothalamic suprachiasmatic nuclei (SCN). This clock is synchronized (entrained) to the external light environment via light input from retinal photoreceptors. However, sleep is not a simple circadian output and also is regulated by a homeostatic process whereby extended wakefulness increases the need for subsequent sleep. As such, the amount and distribution of sleep depends upon the interaction between both circadian and homeostatic processes. Moreover, the study of circadian activity and sleep is not confined only to these specialized fields. Sleep and circadian rhythm disruption is common in many conditions, ranging from neurological and metabolic disorders to aging. Such disruption is associated with a range of negative consequences including cognitive impairment and mood disorders, as well as immune and metabolic dysfunction. As circadian activity and sleep are hallmarks of normal healthy physiology, they also provide valuable welfare indicators. However, traditional methods for the monitoring of circadian rhythms and sleep in mice can require separate specialized resources as well as significant expertise. Here, we outline a low-cost, non-invasive, and open-source method for the simultaneous assessment of circadian activity and sleep in mice. This protocol describes both the assembly of the hardware used and the capture and analysis of data without the need for expertise in electronics or data processing. © 2020 Wiley Periodicals LLC. Basic Protocol: Assembly of a PIR system for basic activity and sleep recordings Alternate Protocol: Data collection using Raspberry Pi Support Protocol: Circadian analysis using PIR sensors.

4.
Sci Adv ; 6(33): eabb3567, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32851175

RESUMO

Switches between global sleep and wakefulness states are believed to be dictated by top-down influences arising from subcortical nuclei. Using forward genetics and in vivo electrophysiology, we identified a recessive mouse mutant line characterized by a substantially reduced propensity to transition between wake and sleep states with an especially pronounced deficit in initiating rapid eye movement (REM) sleep episodes. The causative mutation, an Ile102Asn substitution in the synaptic vesicular protein, VAMP2, was associated with morphological synaptic changes and specific behavioral deficits, while in vitro electrophysiological investigations with fluorescence imaging revealed a markedly diminished probability of vesicular release in mutants. Our data show that global shifts in the synaptic efficiency across brain-wide networks leads to an altered probability of vigilance state transitions, possibly as a result of an altered excitability balance within local circuits controlling sleep-wake architecture.

5.
Mamm Genome ; 30(3-4): 54-62, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31020388

RESUMO

Spermatogenesis-associated protein 13 (Spata13) is a guanine nucleotide exchange factor (GEF) enriched in discrete brain regions in the adult, with pronounced expression in the extended central amygdala (CeA). Loss of Spata13, also known as the adenomatous polyposis coli exchange factor Asef2, has no identifiable phenotype although it has been shown to reduce the number and size of intestinal tumours in Apc (Min/+) mice. Nevertheless, its brain-related functions have not been investigated. To pursue this, we have generated a Spata13 knockout mouse line using CRISPR-mediated deletion of an exon containing the GTPase domain that is common to multiple isoforms. Homozygous mutants were viable and appeared normal. We subjected both male and female cohorts to a comprehensive battery of behavioural tests designed to investigate particular CeA-related functions. Here, we show that Spata13 modulates social behaviour with homozygous mutants being subordinate to wildtype controls. Furthermore, female homozygotes show increased activity in home cages during the dark phase of the light-dark cycle. In summary, Spata13 modulates social hierarchy in both male and female mice in addition to affecting voluntary activity in females.


Assuntos
Ritmo Circadiano/efeitos da radiação , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Comportamento Social , Animais , Comportamento Animal/efeitos da radiação , Feminino , Fatores de Troca do Nucleotídeo Guanina/genética , Hierarquia Social , Humanos , Masculino , Camundongos , Camundongos Knockout , Fotoperíodo , Predomínio Social
6.
Dis Model Mech ; 12(2)2019 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-30692144

RESUMO

Loss-of-function mutations in a human AMPA receptor-associated protein, ferric chelate reductase 1-like (FRRS1L), are associated with a devastating neurological condition incorporating choreoathetosis, cognitive deficits and epileptic encephalopathies. Furthermore, evidence from overexpression and ex vivo studies has implicated FRRS1L in AMPA receptor biogenesis, suggesting that changes in glutamatergic signalling might underlie the disorder. Here, we investigated the neurological and neurobehavioural correlates of the disorder using a mouse Frrs1l null mutant. The study revealed several neurological defects that mirrored those seen in human patients. We established that mice lacking Frrs1l suffered from a broad spectrum of early-onset motor deficits with no progressive, age-related deterioration. Moreover, Frrs1l-/- mice were hyperactive, irrespective of test environment, exhibited working memory deficits and displayed significant sleep fragmentation. Longitudinal electroencephalographic (EEG) recordings also revealed abnormal EEG results in Frrs1l-/- mice. Parallel investigations into disease aetiology identified a specific deficiency in AMPA receptor levels in the brain of Frrs1l-/- mice, while the general levels of several other synaptic components remained unchanged, with no obvious alterations in the number of synapses. Furthermore, we established that Frrsl1 deletion results in an increased proportion of immature AMPA receptors, indicated by incomplete glycosylation of GLUA2 (also known as GRIA2) and GLUA4 (also known as GRIA4) AMPA receptor proteins. This incomplete maturation leads to cytoplasmic retention and a reduction of those specific AMPA receptor levels in the postsynaptic membrane. Overall, this study determines, for the first time in vivo, how loss of FRRS1L function can affect glutamatergic signalling, and provides mechanistic insight into the development and progression of a human hyperkinetic disorder.This article has an associated First Person interview with the first author of the paper.


Assuntos
Cognição , Fenômenos Eletrofisiológicos , Proteínas de Membrana/metabolismo , Atividade Motora , Proteínas do Tecido Nervoso/metabolismo , Sistema Nervoso/crescimento & desenvolvimento , Sistema Nervoso/patologia , Receptores de AMPA/metabolismo , Sinapses/metabolismo , Animais , Animais Recém-Nascidos , Tamanho Corporal , Encéfalo/metabolismo , Encéfalo/patologia , Transtornos Cognitivos/patologia , Citoplasma/metabolismo , Glicosilação , Proteínas de Membrana/genética , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/genética , Sistema Nervoso/fisiopatologia , Sono , Análise de Sobrevida
7.
Mech Ageing Dev ; 177: 91-102, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30290161

RESUMO

Geroprotectors, a class of drugs targeting multiple deficits occurring with age, necessitate the development of new animal models to test their efficacy. The COST Action MouseAGE is a European network whose aim is to reach consensus on the translational path required for geroprotectors, interventions targeting the biology of ageing. In our previous work we identified frailty and loss of resilience as a potential target for geroprotectors. Frailty is the result of an accumulation of deficits, which occurs with age and reduces the ability to respond to adverse events (physical resilience). Modelling frailty and physical resilience in mice is challenging for many reasons. There is no consensus on the precise definition of frailty and resilience in patients or on how best to measure it. This makes it difficult to evaluate available mouse models. In addition, the characterization of those models is poor. Here we review potential models of physical resilience, focusing on those where there is some evidence that the administration of acute stressors requires integrative responses involving multiple tissues and where aged mice showed a delayed recovery or a worse outcome then young mice in response to the stressor. These models include sepsis, trauma, drug- and radiation exposure, kidney and brain ischemia, exposure to noise, heat and cold shock.


Assuntos
Envelhecimento/fisiologia , Modelos Biológicos , Animais , Camundongos
8.
FASEB J ; 32(8): 4302-4314, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29561690

RESUMO

Cryptochromes 1 and 2 (CRY1/2) are key components of the negative limb of the mammalian circadian clock. Like many peripheral tissues, Cry1 and -2 are expressed in the retina, where they are thought to play a role in regulating rhythmic physiology. However, studies differ in consensus as to their localization and function, and CRY1 immunostaining has not been convincingly demonstrated in the retina. Here we describe the expression and function of CRY1 and -2 in the mouse retina in both sexes. Unexpectedly, we show that CRY1 is expressed throughout all retinal layers, whereas CRY2 is restricted to the photoreceptor layer. Retinal period 2::luciferase recordings from CRY1-deficient mice show reduced clock robustness and stability, while those from CRY2-deficient mice show normal, albeit long-period, rhythms. In functional studies, we then investigated well-defined rhythms in retinal physiology. Rhythms in the photopic electroretinogram, contrast sensitivity, and pupillary light response were all severely attenuated or abolished in CRY1-deficient mice. In contrast, these physiological rhythms are largely unaffected in mice lacking CRY2, and only photopic electroretinogram rhythms are affected. Together, our data suggest that CRY1 is an essential component of the mammalian retinal clock, whereas CRY2 has a more limited role.-Wong, J. C. Y., Smyllie, N. J., Banks, G. T., Pothecary, C. A., Barnard, A. R., Maywood, E. S., Jagannath, A., Hughes, S., van der Horst, G. T. J., MacLaren, R. E., Hankins, M. W., Hastings, M. H., Nolan, P. M., Foster, R. G., Peirson, S. N. Differential roles for cryptochromes in the mammalian retinal clock.


Assuntos
Criptocromos/metabolismo , Mamíferos/metabolismo , Mamíferos/fisiologia , Retina/metabolismo , Retina/fisiologia , Animais , Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Eletrorretinografia/métodos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Células Fotorreceptoras/metabolismo , Células Fotorreceptoras/fisiologia
9.
J Neurosci Methods ; 300: 37-47, 2018 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-28456660

RESUMO

An important factor in reducing variability in mouse test outcomes has been to develop assays that can be used for continuous automated home cage assessment. Our experience has shown that this has been most evidenced in long-term assessment of wheel-running activity in mice. Historically, wheel-running in mice and other rodents have been used as a robust assay to determine, with precision, the inherent period of circadian rhythms in mice. Furthermore, this assay has been instrumental in dissecting the molecular genetic basis of mammalian circadian rhythms. In teasing out the elements of this test that have determined its robustness - automated assessment of an unforced behaviour in the home cage over long time intervals - we and others have been investigating whether similar test apparatus could be used to accurately discriminate differences in distinct behavioural parameters in mice. Firstly, using these systems, we explored behaviours in a number of mouse inbred strains to determine whether we could extract biologically meaningful differences. Secondly, we tested a number of relevant mutant lines to determine how discriminative these parameters were. Our findings show that, when compared to conventional out-of-cage phenotyping, a far deeper understanding of mouse mutant phenotype can be established by monitoring behaviour in the home cage over one or more light:dark cycles.


Assuntos
Comportamento Animal/fisiologia , Pesquisa Comportamental/métodos , Ritmo Circadiano/fisiologia , Abrigo para Animais , Fotoperíodo , Corrida/fisiologia , Bem-Estar do Animal , Animais , Pesquisa Comportamental/instrumentação , Camundongos
10.
Mol Metab ; 6(11): 1419-1428, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-29107289

RESUMO

OBJECTIVE: Genetic studies in obese rodents and humans can provide novel insights into the mechanisms involved in energy homeostasis. METHODS: In this study, we genetically mapped the chromosomal region underlying the development of severe obesity in a mouse line identified as part of a dominant N-ethyl-N-nitrosourea (ENU) mutagenesis screen. We characterized the metabolic and behavioral phenotype of obese mutant mice and examined changes in hypothalamic gene expression. In humans, we examined genetic data from people with severe early onset obesity. RESULTS: We identified an obese mouse heterozygous for a missense mutation (pR108W) in orthopedia homeobox (Otp), a homeodomain containing transcription factor required for the development of neuroendocrine cell lineages in the hypothalamus, a region of the brain important in the regulation of energy homeostasis. OtpR108W/+ mice exhibit increased food intake, weight gain, and anxiety when in novel environments or singly housed, phenotypes that may be partially explained by reduced hypothalamic expression of oxytocin and arginine vasopressin. R108W affects the highly conserved homeodomain, impairs DNA binding, and alters transcriptional activity in cells. We sequenced OTP in 2548 people with severe early-onset obesity and found a rare heterozygous loss of function variant in the homeodomain (Q153R) in a patient who also had features of attention deficit disorder. CONCLUSIONS: OTP is involved in mammalian energy homeostasis and behavior and appears to be necessary for the development of hypothalamic neural circuits. Further studies will be needed to investigate the contribution of rare variants in OTP to human energy homeostasis.


Assuntos
Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Sequência de Aminoácidos , Animais , Ansiedade/metabolismo , Sequência de Bases , Encéfalo/metabolismo , Mapeamento Cromossômico , Bases de Dados Genéticas , Feminino , Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento/genética , Genes Homeobox , Proteínas de Homeodomínio/fisiologia , Humanos , Hipotálamo/metabolismo , Masculino , Camundongos , Proteínas do Tecido Nervoso/fisiologia , Sistemas Neurossecretores/metabolismo , Obesidade/metabolismo , Fatores de Transcrição/genética , Transcriptoma/genética
11.
J Biol Rhythms ; 32(5): 433-443, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28816086

RESUMO

The transcription factor zinc finger homeobox 3 (ZFHX3) plays a key role in coupling intracellular transcriptional-translational oscillations with intercellular synchrony in mouse suprachiasmatic nucleus (SCN). However, like many key players in central nervous system function, ZFHX3 serves an important role in neurulation and neuronal terminal differentiation while retaining discrete additional functions in the adult SCN. Recently, using a dominant missense mutation in mouse Zfhx3, we established that this gene can modify circadian period and sleep in adult animals. Nevertheless, we were still concerned that the neurodevelopmental consequences of ZFHX3 dysfunction in this mutant may interfere with, or confound, its critical adult-specific roles in SCN circadian function. To circumvent the developmental consequences of Zfhx3 deletion, we crossed a conditional null Zfhx3 mutant to an inducible, ubiquitously expressed Cre line (B6.Cg-Tg(UBC-cre/ERT2)1Ejb/J). This enabled us to assess circadian behavior in the same adult animals both before and after Cre-mediated excision of the critical Zfhx3 exons using tamoxifen treatment. Remarkably, we found a strong and significant alteration in circadian behavior in tamoxifen-treated homozygous animals with no phenotypic changes in heterozygous or control animals. Cre-mediated excision of Zfhx3 critical exons in adult animals resulted in shortening of the period of wheel-running in constant darkness by more than 1 h in the majority of homozygotes while, in 30% of animals, excision resulted in complete behavioral arrhythmicity. In addition, we found that homozygous animals reentrain almost immediately to 6-h phase advances in the light-dark cycle. No additional overt phenotypic changes were evident in treated homozygous animals. These findings confirm a sustained and significant role for ZFHX3 in maintaining rhythmicity in the adult mammalian circadian system.


Assuntos
Relógios Circadianos , Ritmo Circadiano , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/fisiologia , Fatores Etários , Animais , Relógios Circadianos/efeitos dos fármacos , Relógios Circadianos/genética , Ritmo Circadiano/genética , Regulação da Expressão Gênica , Camundongos , Camundongos Knockout , Mutação , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Fotoperíodo , Núcleo Supraquiasmático/fisiologia , Tamoxifeno/farmacologia
12.
Nat Commun ; 7: 12444, 2016 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-27534441

RESUMO

Determining the genetic bases of age-related disease remains a major challenge requiring a spectrum of approaches from human and clinical genetics to the utilization of model organism studies. Here we report a large-scale genetic screen in mice employing a phenotype-driven discovery platform to identify mutations resulting in age-related disease, both late-onset and progressive. We have utilized N-ethyl-N-nitrosourea mutagenesis to generate pedigrees of mutagenized mice that were subject to recurrent screens for mutant phenotypes as the mice aged. In total, we identify 105 distinct mutant lines from 157 pedigrees analysed, out of which 27 are late-onset phenotypes across a range of physiological systems. Using whole-genome sequencing we uncover the underlying genes for 44 of these mutant phenotypes, including 12 late-onset phenotypes. These genes reveal a number of novel pathways involved with age-related disease. We illustrate our findings by the recovery and characterization of a novel mouse model of age-related hearing loss.


Assuntos
Envelhecimento/genética , Testes Genéticos , Mutagênese/genética , Animais , Cóclea/metabolismo , Modelos Animais de Doenças , Epitélio/ultraestrutura , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Feminino , Audição/genética , Masculino , Camundongos Endogâmicos C57BL , Mutação/genética , Linhagem , Fenótipo
13.
Mamm Genome ; 27(7-8): 332-40, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27137838

RESUMO

Virtually, all biological processes in the body are modulated by an internal circadian clock which optimizes physiological and behavioral performance according to the changing demands of the external 24-h world. This circadian clock undergoes a number of age-related changes, at both the physiological and molecular levels. While these changes have been considered to be part of the normal aging process, there is increasing evidence that disruptions to the circadian system can substantially impact upon aging and these impacts will have clear health implications. Here we review the current data of how both the physiological and core molecular clocks change with age and how feedback from external cues may modulate the aging of the circadian system.


Assuntos
Envelhecimento/genética , Relógios Circadianos/genética , Ritmo Circadiano/genética , Envelhecimento/fisiologia , Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos
14.
Neurobiol Aging ; 36(1): 380-93, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25179226

RESUMO

The circadian system is entrained to the environmental light/dark cycle via retinal photoreceptors and regulates numerous aspects of physiology and behavior, including sleep. These processes are all key factors in healthy aging showing a gradual decline with age. Despite their importance, the exact mechanisms underlying this decline are yet to be fully understood. One of the most effective tools we have to understand the genetic factors underlying these processes are genetically inbred mouse strains. The most commonly used reference mouse strain is C57BL/6J, but recently, resources such as the International Knockout Mouse Consortium have started producing large numbers of mouse mutant lines on a pure genetic background, C57BL/6N. Considering the substantial genetic diversity between mouse strains we expect there to be phenotypic differences, including differential effects of aging, in these and other strains. Such differences need to be characterized not only to establish how different mouse strains may model the aging process but also to understand how genetic background might modify age-related phenotypes. To ascertain the effects of aging on sleep/wake behavior, circadian rhythms, and light input and whether these effects are mouse strain-dependent, we have screened C57BL/6J, C57BL/6N, C3H-HeH, and C3H-Pde6b+ mouse strains at 5 ages throughout their life span. Our data show that sleep, circadian, and light input parameters are all disrupted by the aging process. Moreover, we have cataloged a number of strain-specific aging effects, including the rate of cataract development, decline in the pupillary light response, and changes in sleep fragmentation and the proportion of time spent asleep.


Assuntos
Envelhecimento/genética , Ritmo Circadiano/genética , Ritmo Circadiano/fisiologia , Células Fotorreceptoras de Vertebrados/fisiologia , Sono/genética , Sono/fisiologia , Acuidade Visual/genética , Acuidade Visual/fisiologia , Animais , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos
15.
J Neurosci ; 33(17): 7145-53, 2013 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-23616524

RESUMO

The circadian clock of the suprachiasmatic nucleus (SCN) drives daily rhythms of behavior. Cryptochromes (CRYs) are powerful transcriptional repressors within the molecular negative feedback loops at the heart of the SCN clockwork, where they periodically suppress their own expression and that of clock-controlled genes. To determine the differential contributions of CRY1 and CRY2 within circadian timing in vivo, we exploited the N-ethyl-N-nitrosourea-induced afterhours mutant Fbxl3(Afh) to stabilize endogenous CRY. Importantly, this was conducted in CRY2- and CRY1-deficient mice to test each CRY in isolation. In both CRY-deficient backgrounds, circadian rhythms of wheel-running and SCN bioluminescence showed increased period length with increased Fbxl3(Afh) dosage. Although both CRY proteins slowed the clock, CRY1 was significantly more potent than CRY2, and in SCN slices, CRY1 but not CRY2 prolonged the interval of transcriptional suppression. Selective CRY-stabilization demonstrated that both CRYs are endogenous transcriptional repressors of clock-controlled genes, but again CRY1 was preeminent. Finally, although Cry1(-/-);Cry2(-/-) mice were behaviorally arrhythmic, their SCN expressed short period (~18 h) rhythms with variable stability. Fbxl3(Afh/Afh) had no effect on these CRY-independent rhythms, confirming its circadian action is mediated exclusively via CRYs. Thus, stabilization of both CRY1 and CRY2 are necessary and sufficient to explain circadian period lengthening by Fbxl3(Afh/Afh). Both CRY proteins dose-dependently lengthen the intrinsic, high-frequency SCN rhythm, and CRY2 also attenuates the more potent period-lengthening effects of CRY1. Incorporation of CRY-mediated transcriptional feedback thus confers stability to intrinsic SCN oscillations, establishing periods between 18 and 29 h, as determined by selective contributions of CRY1 and CRY2.


Assuntos
Relógios Circadianos/genética , Criptocromos/fisiologia , Proteínas F-Box/fisiologia , Mutação/fisiologia , Núcleo Supraquiasmático/fisiologia , Animais , Animais Recém-Nascidos , Ritmo Circadiano/genética , Criptocromos/genética , Proteínas F-Box/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Técnicas de Cultura de Órgãos
16.
J Neurosci ; 31(14): 5483-94, 2011 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-21471385

RESUMO

The cytoplasmic dynein complex is fundamentally important to all eukaryotic cells for transporting a variety of essential cargoes along microtubules within the cell. This complex also plays more specialized roles in neurons. The complex consists of 11 types of protein that interact with each other and with external adaptors, regulators and cargoes. Despite the importance of the cytoplasmic dynein complex, we know comparatively little of the roles of each component protein, and in mammals few mutants exist that allow us to explore the effects of defects in dynein-controlled processes in the context of the whole organism. Here we have taken a genotype-driven approach in mouse (Mus musculus) to analyze the role of one subunit, the dynein light intermediate chain 1 (Dync1li1). We find that, surprisingly, an N235Y point mutation in this protein results in altered neuronal development, as shown from in vivo studies in the developing cortex, and analyses of electrophysiological function. Moreover, mutant mice display increased anxiety, thus linking dynein functions to a behavioral phenotype in mammals for the first time. These results demonstrate the important role that dynein-controlled processes play in the correct development and function of the mammalian nervous system.


Assuntos
Comportamento Animal/fisiologia , Dineínas do Citoplasma/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Fenótipo , Mutação Puntual/genética , Animais , Animais Recém-Nascidos , Asparagina/genética , Contagem de Células/métodos , Células Cultivadas , Córtex Cerebral/citologia , Dendritos/genética , Embrião de Mamíferos , Feminino , Fibroblastos/fisiologia , Fibroblastos/ultraestrutura , Gânglios Espinais/citologia , Proteínas de Fluorescência Verde/genética , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Atividade Motora/genética , Proteínas do Tecido Nervoso , Condução Nervosa/genética , Neurônios/classificação , Neurônios/citologia , Neurônios/fisiologia , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/genética , Desempenho Psicomotor , Estatísticas não Paramétricas , Tirosina/genética , Levantamento de Peso/fisiologia
17.
Curr Protoc Mouse Biol ; 1(3): 369-81, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26068996

RESUMO

In most organisms, physiological variables are regulated by an internal clock. This endogenous circadian (∼24-hr) clock enables organisms to anticipate daily environmental changes and modify behavioral and physiological functions appropriately. Processes regulated by the circadian clock include sleep-wake and locomotor activity, core body temperature, metabolism, water/food intake, and available hormone levels. At the core of the mammalian circadian system are molecular oscillations within the hypothalamic suprachiasmatic nucleus. These oscillations are modifiable by signals from the environment (so called zeitgebers or time-givers) and, once integrated within the suprachiasmatic nucleus, are conveyed to remote neural circuits where output rhythms are regulated. Disrupting any of a number of neural processes can affect how rhythms are generated and relayed to the periphery and disturbances in circadian/entrainment parameters are associated with numerous human conditions. These non-invasive protocols can be used to determine whether circadian/entrainment parameters are affected in mouse mutants or treatment groups. Curr. Protoc. Mouse Biol. 1:369-381 © 2011 by John Wiley & Sons, Inc.

18.
Nat Genet ; 42(12): 1086-92, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21076408

RESUMO

Genome-wide association studies have identified SNPs within FTO, the human fat mass and obesity-associated gene, that are strongly associated with obesity. Individuals homozygous for the at-risk rs9939609 A allele weigh, on average, ~3 kg more than individuals with the low-risk T allele. Mice that lack FTO function and/or Fto expression display increased energy expenditure and a lean phenotype. We show here that ubiquitous overexpression of Fto leads to a dose-dependent increase in body and fat mass, irrespective of whether mice are fed a standard or a high-fat diet. Our results suggest that increased body mass results primarily from increased food intake. Mice with increased Fto expression on a high-fat diet develop glucose intolerance. This study provides the first direct evidence that increased Fto expression causes obesity in mice.


Assuntos
Comportamento Alimentar/fisiologia , Obesidade/genética , Oxo-Ácido-Liases/metabolismo , Adiposidade/efeitos dos fármacos , Adiposidade/genética , Dioxigenase FTO Dependente de alfa-Cetoglutarato , Animais , Área Sob a Curva , Temperatura Corporal , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/genética , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/farmacologia , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/genética , Comportamento Alimentar/efeitos dos fármacos , Feminino , Glucose/metabolismo , Teste de Tolerância a Glucose , Homeostase/genética , Masculino , Camundongos , Oxigenases de Função Mista , Modelos Animais , Atividade Motora/efeitos dos fármacos , Obesidade/sangue , Oxo-Ácido-Liases/genética
19.
J Biol Chem ; 285(51): 39922-34, 2010 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-20889981

RESUMO

A single amino acid change, F580Y (Legs at odd angles (Loa), Dync1h1(Loa)), in the highly conserved and overlapping homodimerization, intermediate chain, and light intermediate chain binding domain of the cytoplasmic dynein heavy chain can cause severe motor and sensory neuron loss in mice. The mechanism by which the Loa mutation impairs the neuron-specific functions of dynein is not understood. To elucidate the underlying molecular mechanisms of neurodegeneration arising from this mutation, we applied a cohort of biochemical methods combined with in vivo assays to systemically study the effects of the mutation on the assembly of dynein and its interaction with dynactin. We found that the Loa mutation in the heavy chain leads to increased affinity of this subunit of cytoplasmic dynein to light intermediate and a population of intermediate chains and a suppressed association of dynactin to dynein. These data suggest that the Loa mutation drives the assembly of cytoplasmic dynein toward a complex with lower affinity to dynactin and thus impairing transport of cargos that tether to the complex via dynactin. In addition, we detected up-regulation of kinesin light chain 1 (KLC1) and its increased association with dynein but reduced microtubule-associated KLC1 in the Loa samples. We provide a model describing how up-regulation of KLC1 and its interaction with cytoplasmic dynein in Loa could play a regulatory role in restoring the retrograde and anterograde transport in the Loa neurons.


Assuntos
Dineínas do Citoplasma/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Mutação , Doenças Neurodegenerativas/metabolismo , Animais , Dineínas do Citoplasma/genética , Complexo Dinactina , Camundongos , Camundongos Mutantes , Proteínas Associadas aos Microtúbulos/genética , Doenças Neurodegenerativas/genética
20.
PLoS One ; 5(7): e11682, 2010 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-20657784

RESUMO

BACKGROUND: Intracellular transport of cargoes including organelles, vesicles, signalling molecules, protein complexes, and RNAs, is essential for normal function of eukaryotic cells. The cytoplasmic dynein complex is an important motor that moves cargos along microtubule tracks within the cell. In mammals this multiprotein complex includes dynein intermediate chains 1 and 2 which are encoded by two genes, Dync1i1 and Dync1i2. These proteins are involved in dynein cargo binding and dynein complexes with different intermediate chains bind to specific cargoes, although the mechanisms to achieve this are not known. The DYNC1I1 and DYNC1I2 proteins are translated from different splice isoforms, and specific forms of each protein are essential for the function of different dynein complexes in neurons. METHODOLOGY/PRINCIPAL FINDINGS: Here we have undertaken a systematic survey of the dynein intermediate chain splice isoforms in mouse, basing our study on mRNA expression patterns in a range of tissues, and on bioinformatics analysis of mouse, rat and human genomic and cDNA sequences. We found a complex pattern of alternative splicing of both dynein intermediate chain genes, with maximum complexity in the embryonic and adult nervous system. We have found novel transcripts, including some with orthologues in human and rat, and a new promoter and alternative non-coding exon 1 for Dync1i2. CONCLUSIONS/SIGNIFICANCE: These data, including the cloned isoforms will be essential for understanding the role of intermediate chains in the cytoplasmic dynein complex, particularly their role in cargo binding within individual tissues including different brain regions.


Assuntos
Citoplasma/metabolismo , Dineínas/metabolismo , Isoformas de Proteínas/metabolismo , Processamento Alternativo/genética , Processamento Alternativo/fisiologia , Animais , Biologia Computacional , Dineínas/genética , Humanos , Camundongos , Isoformas de Proteínas/genética , Ratos
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