Project description:Inosine 5'-phosphate dehydrogenase (impdh) has been well known as a key enzyme in GTP biosynthesis pathway. We found that three isoforms of impdh in zebrafish, namely impdh1a, impdh1b and impdh2, all show robust circadian expression.To examine the molecular functions of three impdh isoforms in zebrafish on the genome scale, we measured the global expression changes of impdh1a, impdh1b and impdh2 morpholino injected larvae (morphants) respectively using RNA-seq. Wild type (WT), control and three impdh morphants were collected at 32 hpf. In our RNA-seq result, we identified 468, 331 and 1166 significant genes affected by impdh1a, impdh1b and impdh2 morpholino (MO) knock-down respectively. Among them, there are limited overlaps between genes affected by different MOs and only 36 genes in common among all three MOs. This indicates that the three impdh isoforms have distinct molecular functions. To knock down the target genes, three impdh MOs and control MO were pressure-injected into 1- to 2-cell stage embryos. WT, control and three impdh morphants were raised at 28°C under 14h: 10h light/dark cycle from birth and sampled simultaneously at 32 hpf. Each group has at least 40 embryos.
Project description:Cell cycle and metabolism are two major outputs controlled by circadian rhythm in many organisms. Here we show that the three processes were linked through inosine 5'-phosphate dehydrogenase (impdh), a rate-limiting enzyme in de novo purine synthesis. We using adult zebrafish as a model system,we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression. The whole-genome transcriptome profiles of adult brain in time-series were assayed on Agilent zebrafish microarrays. We used a similar statistical method to identify zebrafish circadian genes (ZCOG) as our previous study in larval zebrafish. Three isoforms of impdh show strong circadian oscillations in different tissues of zebrafish. impdh1a contributes to the ocular development and pigment synthesis, impdh2 promotes and impdh1b delays the development. By limiting the GTP required by DNA synthesis, impdh2 contributes to the daily rhythm of S phase in cell cycle. Multiple enzymes in the de novo purine synthesis pathway show the same circadian oscillations with peaks similar to impdh2. The circadian expression of this pathway is conserved in mouse liver. In summary, we show that the circadian regulation of de novo purine synthesis that supplies crucial building blocks for DNA replication is critical for gating cell cycle in circadian rhythm. Adult zebrafish were sacrificed and dissected at 4h intervals starting at CT0 in both LD and DD conditions for 12 time points. Total RNA of individual zebrafish brain was extracted using Trizol (Invitrogen, Carlsbad, CA) according to the manufacturerM-bM-^@M-^Ys instruction. Microarrays were manufactured by Agilent Technologies (Agilent Technologies, Palo Alto, CA), containing 43,603 probes for zebrafish whole-genome transcriptional profiling.
Project description:Inosine 5'-phosphate dehydrogenase (impdh) has been well known as a key enzyme in GTP biosynthesis pathway. We found that three isoforms of impdh in zebrafish, namely impdh1a, impdh1b and impdh2, all show robust circadian expression.To examine the molecular functions of three impdh isoforms in zebrafish on the genome scale, we measured the global expression changes of impdh1a, impdh1b and impdh2 morpholino injected larvae (morphants) respectively using RNA-seq. Wild type (WT), control and three impdh morphants were collected at 32 hpf. In our RNA-seq result, we identified 468, 331 and 1166 significant genes affected by impdh1a, impdh1b and impdh2 morpholino (MO) knock-down respectively. Among them, there are limited overlaps between genes affected by different MOs and only 36 genes in common among all three MOs. This indicates that the three impdh isoforms have distinct molecular functions.
Project description:Cell cycle and metabolism are two major outputs controlled by circadian rhythm in many organisms. Here we show that the three processes were linked through inosine 5'-phosphate dehydrogenase (impdh), a rate-limiting enzyme in de novo purine synthesis. We using adult zebrafish as a model system,we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression. The whole-genome transcriptome profiles of adult brain in time-series were assayed on Agilent zebrafish microarrays. We used a similar statistical method to identify zebrafish circadian genes (ZCOG) as our previous study in larval zebrafish. Three isoforms of impdh show strong circadian oscillations in different tissues of zebrafish. impdh1a contributes to the ocular development and pigment synthesis, impdh2 promotes and impdh1b delays the development. By limiting the GTP required by DNA synthesis, impdh2 contributes to the daily rhythm of S phase in cell cycle. Multiple enzymes in the de novo purine synthesis pathway show the same circadian oscillations with peaks similar to impdh2. The circadian expression of this pathway is conserved in mouse liver. In summary, we show that the circadian regulation of de novo purine synthesis that supplies crucial building blocks for DNA replication is critical for gating cell cycle in circadian rhythm.