Background Folic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of fotic acid performing its biological function. Therefore, the dysfunction of di...Background Folic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of fotic acid performing its biological function. Therefore, the dysfunction of dihydrofolate reductase can inhibit the function of folic acid and finally cause the developmental malformations. In this study, we observed the abnormal cardiac phenotypes in dihydrofolate reductase （DHFR） gene knock-down zebrafish embryos, investigated the effect of DHFR on the expression of heart and neural crest derivatives expressed transcript 2 （HAND2） and explored the possible mechanism of DHFR knock-down inducing zebrafish cardiac malformations. Methods Morpholino oligonucleotides were microinjected into fertilized eggs to knock down the functions of DHFR or HAND2. Full length of HAND2 mRNA which was transcribed in vitro was microinjected into fertilized eggs to overexpress HAND2. The cardiac morphologies, the heart rates and the ventricular shortening fraction were observed and recorded under the microscope at 48 hours post fertilization. Whole-mount in situ hybridization and real-time PCR were performed to detect HAND2 expression. Results DHFR or HAND2 knock-down caused the cardiac malformation in zebrafish. The expression of HAND2 was obviously reduced in DHFR knock-down embryos （P〈0.05）. Microinjecting HAND2 mRNA into fertilized eggs can induce HAND2 overexpression. HAND2 overexpression rescued the cardiac malformation phenotypes of DHFR knock-down embryos. Conclusions DHFR plays a crucial role in cardiac development. The down-regulation of HAND2 caused by DHFR knock-down is the possible mechanism of DHFR knock-down inducing the cardiac malformation.展开更多
The TBX1 gene is considered to be the most important gene in the aetiology of DiGeorge syndrome （DGS）.DGS is a human disorder characterised by a number of phenotypic features involving abnormal development of pharyn...The TBX1 gene is considered to be the most important gene in the aetiology of DiGeorge syndrome （DGS）.DGS is a human disorder characterised by a number of phenotypic features involving abnormal development of pharyngeal arches, facial dysmorphogenesis and cardiac outflow tract anomalies. Retinoic acid （RA） deficiency also produces DGS-like phenotypes. The affectd tissues in DGS are derivatives of neural crest cells （NCCs）, which originate from the border between the neural plate and non-neural ectoderm, migrate to specific destinations in the body, and generate a variety of derivatives. In our study, we have explored the hypothesis that tbxl affects NCC development in zebrafish by regulating RA signaling.展开更多
Background Retinoic acid （RA） is a potent signaling molecule that plays pleiotropic roles in patterning, morphogenesis, and organogenesis during embryonic development. The synthesis from retinol （vitamin A） to ret...Background Retinoic acid （RA） is a potent signaling molecule that plays pleiotropic roles in patterning, morphogenesis, and organogenesis during embryonic development. The synthesis from retinol （vitamin A） to retinoic acid requires two sequential oxidative steps. The first step involves the oxidation of retinol to retinal through the action of retinol dehydrogenases. Retinol dehydrogenasesll （RDHll） is a novel zebrafish retinol dehydrogenase. Herein we investigated the role of zebrafish RDHll in heart development and cardiac performance in detail. Methods RDHll specific morpholino was used to reduce the function of RDHll in zebrafish. The gene expressions were observed by using whole mount in situ hybridization. Heart rates were observed and recorded under the microscope from 24 to 72 hours post fertilization （hpf）. The cardiac performance was analyzed by measuring ventricular shortening fraction （VSF）. Results The knock-down of RDHll led to abnormal neural crest cells migration and reduced numbers of neural crest cells in RDHll morphant embryos. The reduced numbers of cardiac neural crest cells also can be seen in RDHll morphant embryos. Furthermore, the morpholino-mediated knock-down of RDHll resulted in the abnormal heart loop. The left-right determining genes expression pattern was altered in RDHll morphant embryos. The impaired cardiac performance was observed in RDHll morphant embryos. Taken together, these data demonstrate that RDHll is essential for the heart development and cardiac performance in zebrafish. Conclusions RDHll plays a important role in the neural crest cells development, and then ultimately affects the heart loop and cardiac performance. These results show for the first time that an enzyme involved in the retinol to retinaldehyde conversion participate in the heart development and cardiac performance in zebrafish.展开更多
文摘Background Folic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of fotic acid performing its biological function. Therefore, the dysfunction of dihydrofolate reductase can inhibit the function of folic acid and finally cause the developmental malformations. In this study, we observed the abnormal cardiac phenotypes in dihydrofolate reductase （DHFR） gene knock-down zebrafish embryos, investigated the effect of DHFR on the expression of heart and neural crest derivatives expressed transcript 2 （HAND2） and explored the possible mechanism of DHFR knock-down inducing zebrafish cardiac malformations. Methods Morpholino oligonucleotides were microinjected into fertilized eggs to knock down the functions of DHFR or HAND2. Full length of HAND2 mRNA which was transcribed in vitro was microinjected into fertilized eggs to overexpress HAND2. The cardiac morphologies, the heart rates and the ventricular shortening fraction were observed and recorded under the microscope at 48 hours post fertilization. Whole-mount in situ hybridization and real-time PCR were performed to detect HAND2 expression. Results DHFR or HAND2 knock-down caused the cardiac malformation in zebrafish. The expression of HAND2 was obviously reduced in DHFR knock-down embryos （P〈0.05）. Microinjecting HAND2 mRNA into fertilized eggs can induce HAND2 overexpression. HAND2 overexpression rescued the cardiac malformation phenotypes of DHFR knock-down embryos. Conclusions DHFR plays a crucial role in cardiac development. The down-regulation of HAND2 caused by DHFR knock-down is the possible mechanism of DHFR knock-down inducing the cardiac malformation.
基金This work was supported by the grants from the National Natural Science Foundation of China （No. 30772352 and No. 30972959）.
文摘The TBX1 gene is considered to be the most important gene in the aetiology of DiGeorge syndrome （DGS）.DGS is a human disorder characterised by a number of phenotypic features involving abnormal development of pharyngeal arches, facial dysmorphogenesis and cardiac outflow tract anomalies. Retinoic acid （RA） deficiency also produces DGS-like phenotypes. The affectd tissues in DGS are derivatives of neural crest cells （NCCs）, which originate from the border between the neural plate and non-neural ectoderm, migrate to specific destinations in the body, and generate a variety of derivatives. In our study, we have explored the hypothesis that tbxl affects NCC development in zebrafish by regulating RA signaling.
基金This work was supported by the grants from the National Natural Science Foundation of China （No. 30972959） and Doctoral Fund of Ministry of Education of China （new teacher） （No. 200802461110）.
文摘Background Retinoic acid （RA） is a potent signaling molecule that plays pleiotropic roles in patterning, morphogenesis, and organogenesis during embryonic development. The synthesis from retinol （vitamin A） to retinoic acid requires two sequential oxidative steps. The first step involves the oxidation of retinol to retinal through the action of retinol dehydrogenases. Retinol dehydrogenasesll （RDHll） is a novel zebrafish retinol dehydrogenase. Herein we investigated the role of zebrafish RDHll in heart development and cardiac performance in detail. Methods RDHll specific morpholino was used to reduce the function of RDHll in zebrafish. The gene expressions were observed by using whole mount in situ hybridization. Heart rates were observed and recorded under the microscope from 24 to 72 hours post fertilization （hpf）. The cardiac performance was analyzed by measuring ventricular shortening fraction （VSF）. Results The knock-down of RDHll led to abnormal neural crest cells migration and reduced numbers of neural crest cells in RDHll morphant embryos. The reduced numbers of cardiac neural crest cells also can be seen in RDHll morphant embryos. Furthermore, the morpholino-mediated knock-down of RDHll resulted in the abnormal heart loop. The left-right determining genes expression pattern was altered in RDHll morphant embryos. The impaired cardiac performance was observed in RDHll morphant embryos. Taken together, these data demonstrate that RDHll is essential for the heart development and cardiac performance in zebrafish. Conclusions RDHll plays a important role in the neural crest cells development, and then ultimately affects the heart loop and cardiac performance. These results show for the first time that an enzyme involved in the retinol to retinaldehyde conversion participate in the heart development and cardiac performance in zebrafish.
