Project description:The cone-rod homeobox gene (Crx) encodes Crx, a transcription factor selectively expressed in two cell types, retinal photoreceptors and the melatonin secreting pinealocytes of the pineal gland. In this report the role of Crx in regulating gene expression in the mammalian pineal gland was extended using Affymetrix GeneChip technology. Deletion of Crx results in broad modulation of the mouse pineal transcriptome, including a >2-fold downregulation of 543 genes and a >2-fold upregulation of 745 genes. In addition to Crx, there was a >10-fold downregulation of 13 other genes. Of special interest was the discovery of a link between Crx and the homeobox gene Hoxc4, which was upregulated ~20-fold in the Crx-/- pineal gland. Analysis of night and day expression of genes indicated that a set of 51 genes exhibited differential expression in control animals. Of these genes, only eight were also differentially expressed in Crx-/- animals. This group included Aanat, which encodes the enzyme that controls the daily rhythm in melatonin synthesis in the vertebrate pineal gland. Accordingly, Crx appears to be essential for the 24-hour rhythmic component of expression of some genes in the pineal gland. In the Crx-/- mouse pineal gland, 41 genes exhibited differential night/day expression that was not seen in control animals, suggesting that Crx may function to modulate rhythmic expression of these genes as well. Together, the results of this investigation indicate that Crx broadly modulates the pineal transcriptome, perhaps in part through suppressive effects on expression of the homeobox gene Hoxc4. Pineal glands from control (129sv) mice and Crx-/- mice were collected at ZT6 and ZT20 for RNA extraction and hybridization on Affymetrix mouse 430_2 chip. Each condition were performed as triplicats. SUPPLEMENTARY FILES: The GCOS signal intensity data were analyzed using ChipInspector (Genomatix) version 2.1. FDR= 0, p-value <0.05, cut off=1, region size = 300 bp and 4 and 5 significant probes. Log(2) fold change independently of time of day. Up regulated genes: genes which are up regulated in Crx-/- compared to the control; down regulated genes: genes which are down regulated in Crx-/- compared to the control.
Project description:The cone-rod homeobox gene (Crx) encodes Crx, a transcription factor selectively expressed in two cell types, retinal photoreceptors and the melatonin secreting pinealocytes of the pineal gland. In this report the role of Crx in regulating gene expression in the mammalian pineal gland was extended using Affymetrix GeneChip technology. Deletion of Crx results in broad modulation of the mouse pineal transcriptome, including a >2-fold downregulation of 543 genes and a >2-fold upregulation of 745 genes. In addition to Crx, there was a >10-fold downregulation of 13 other genes. Of special interest was the discovery of a link between Crx and the homeobox gene Hoxc4, which was upregulated ~20-fold in the Crx-/- pineal gland. Analysis of night and day expression of genes indicated that a set of 51 genes exhibited differential expression in control animals. Of these genes, only eight were also differentially expressed in Crx-/- animals. This group included Aanat, which encodes the enzyme that controls the daily rhythm in melatonin synthesis in the vertebrate pineal gland. Accordingly, Crx appears to be essential for the 24-hour rhythmic component of expression of some genes in the pineal gland. In the Crx-/- mouse pineal gland, 41 genes exhibited differential night/day expression that was not seen in control animals, suggesting that Crx may function to modulate rhythmic expression of these genes as well. Together, the results of this investigation indicate that Crx broadly modulates the pineal transcriptome, perhaps in part through suppressive effects on expression of the homeobox gene Hoxc4.
Project description:NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures. NeuroD1 mRNA is highly abundant in the adult mammalian pineal gland and exhibits a developmental expression pattern similar to the retina. This is consistent with the common evolutionary origin of pinealocytes and retinal photoreceptors. Pinealocytes and retinal photoreceptors express a shared set of phototransduction genes and submammalian pinealocytes are photosensitive. In contrast to the retina, the pineal gland is a relatively homogeneous structure, composed 95% of pinealocytes. This makes the pineal gland a particularly useful model for understanding photoreceptor cell biology. The loss of NeuroD1 in the retina results in progressive photoreceptor degeneration and the molecular mechanisms underlying this retinal degeneration phenotype remain unknown. Similarly, the role that NeuroD1 plays in the pineal gland is unknown. To determine the function of NeuroD1 in the pineal gland and retina, a Cre/loxP recombination strategy was used to selectively target a NeuroD1 floxed allele and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, a transcription factor selectively expressed in the pineal gland and retina. Pineal and retinal tissues from two-month-old NeuroD1 cKO and control animals were used in microarray studies to identify candidate genes responsible for the photoreceptor degeneration phenotype. The Cre/loxP recombination strategy was used to target a NeuroD1 floxed allele and generate NeuroD1 conditional knockout mice (NeuroD1floxed::Crx-Cre+/-). NeuroD1 floxed mice (NeuroD1floxed::Crx-Cre-/-) served as the controls. Pineal glands and retinas from two-month-old control and conditional knockout mice were collected at ZT6 and ZT20. 3 pools of 6 pineal glands per genotype and respective time of day were collected for each sample. Similarly, 3 pools of 6 retinas each were also collected. RNA from each pool was extracted and hybridized on the Affymetrix Mouse 430 2.0 array.
Project description:Circadian rhythmicity in renal function suggests a requirement for circadian adaptations in renal metabolism. We studied circadian changes in renal metabolic pathways using integrated transcriptomic, proteomic and metabolomic analysis performed on control mice and mice deficient in the circadian clock gene Bmal1 in the renal tubule (cKOt mice). Proteins were extracted from whole kidneys of 60 mice. Of these, 30 were conditional knockouts of Arntl (Bmal1) and 30 were of control genotype. They were housed under 12-hours light/12-hours dark cycles and were sacrificed at six different time points: zeitgeber time ZT 0, ZT 4, ZT 8, ZT 12, ZT 16, ZT 20 ( ZT 0 being the time of light on and ZT 12 the time of light off). Five replicates per genotype and time point were analysed.
Project description:NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures. NeuroD1 mRNA is highly abundant in the adult mammalian pineal gland and exhibits a developmental expression pattern similar to the retina. This is consistent with the common evolutionary origin of pinealocytes and retinal photoreceptors. Pinealocytes and retinal photoreceptors express a shared set of phototransduction genes and submammalian pinealocytes are photosensitive. In contrast to the retina, the pineal gland is a relatively homogeneous structure, composed 95% of pinealocytes. This makes the pineal gland a particularly useful model for understanding photoreceptor cell biology. The loss of NeuroD1 in the retina results in progressive photoreceptor degeneration and the molecular mechanisms underlying this retinal degeneration phenotype remain unknown. Similarly, the role that NeuroD1 plays in the pineal gland is unknown. To determine the function of NeuroD1 in the pineal gland and retina, a Cre/loxP recombination strategy was used to selectively target a NeuroD1 floxed allele and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, a transcription factor selectively expressed in the pineal gland and retina. Pineal and retinal tissues from two-month-old NeuroD1 cKO and control animals were used in microarray studies to identify candidate genes responsible for the photoreceptor degeneration phenotype.
Project description:Light is the primary environmental cue in resetting the phase of circadian pacemaker in vertebrates. In birds, the effect of light is partly mediated by modulating the levels of circadian genes in the pineal gland. To further elucidate the mechanism by which light resets the circadian clock, we studied gene expression in the chicken pineal gland under acutely extended light period. Three paradigms of treatments were used in this study. For each paradigm, chicks were assigned at random to control treatment (control groups) or light treatment (light groups). All birds in control groups were given 12 h light and 12 h dark period (LD 12:12). Light-on time is referred to as Zeitgeber Time 0 (ZT0). In paradigm 1, birds in the light group (n =25 for each of the groups in each paradigm) were acclimated to LD 12:12 for one week in the same light scheme as were the control birds, then exposed to light for 2 h during the subjective late night (ZT22 to ZT24) on the last day. All birds (including the controls) were sacrificed at ZT0. Pineal glands were dissected and 5-6 pineal glands were pooled for the preparation of one RNA sample. In paradigm 2, birds in the light group were acclimated as in paradigm 1 for one week, then exposed to light for 2 h during the early subjective night (ZT12 to ZT14) on the last day. All birds (including controls) were sacrificed at ZT14. The pineal glands were also pooled as before. In paradigm 3, birds in the light group (n = 25) were kept in LD 15:9 cycle all the time, and all birds (including controls) were sacrificed at ZT14. Similarly, 5-6 pineal glands in the same treatment were pooled.