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1.
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
2.
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
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