Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
Isocitrate dehydrogenases (IDHs) catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG), generating NADPH to maintain cellular redox balance. Among the three isoforms, cytosolic Idh1 and mitochondrial Idh2 are NADP+-dependent enzymes that are essential for metabolic homeostasis. Although Idh1 and Idh2 have been extensively studied in cancer and other metabolic disorders, their roles in vertebrate development remain understudied. To address this gap, this study investigated the roles of Idh1 and Idh2 in kidney development in Xenopus laevis. Both genes were expressed in the pronephric region, and morpholino-mediated knockdown caused pronephric defects, which were more severe in idh1-depleted embryos. Wild-type idh1* mRNA restored pronephric marker expression, confirming specificity. Notably, the oncogenic idh1*R132H variant also rescued the pronephric defects induced by idh1 knockdown, indicating that its neomorphic activity is absent under embryonic metabolic conditions. These findings identify Idh1 and Idh2 as key regulators of pronephric morphogenesis and reveal a developmental function of Idh1 that is distinct from its canonical catalytic role.
Fig. 1. Developmental expression profiles of idh1 and idh2 revealed through RT-PCR and WISH. (A) RT-PCR analysis showing stage-specific expression of idh1 and idh2. Ornithine decarboxylase (odc) was used as a loading control. (B) Semi-quantitative analysis of RTPCR results. Band intensities were measured using ImageJ, and the intensity of each gene at the indicated developmental stages was normalized to the corresponding odc band. Normalized values were plotted to compare the stage-specific expression dynamics of idh1 and idh2. (C) Whole-mount in situ hybridization (WISH) showing idh1 and idh2 expression in the craniofacial region, somites, and pronephric kidney, including the IT and distal dPT. atp1a1 was used as an anatomical reference to identify pronephric tubule regions. Scale bars: 500 um. RT-PCR, reverse transcriptionpolymerase chain reaction; WISH, whole-mount in situ hybridization; s, somites; PT, proximal tubule; IT, intermediate tubule; dPT, distal pronephric tubule.
atp1a1 (ATPase Na+/K+ transporting subunit alpha 1) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 35 & 36, lateral view, anterior left, dorsal up.
idh1 () gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage [STAGE], lateral view, anterior left, dorsal up.
idh2 () gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage [STAGE], lateral view, anterior left, dorsal up.
Fig. 2. Knockdown of idh1 and idh2 disrupts pronephric development in Xenopus laevis. (A) WISH showing reduced smp30 and atp1a1 expression in idh1 and idh2 morphants, with a more pronounced reduction observed in idh1 morphants. (B,C) Quantification of embryos classified as defective based on reduced staining intensity and/or abnormal spatial patterning of smp30 (B) and atp1a1 (C) expression, as represented in (A). **p<0.01, ***p<0.001; one-way ANOVA followed by Dunnett’s multiple comparisons test. Scale bars: 500 μm. MO, morpholino oligonucleotide; WISH, whole-mount in situ hybridization; ANOVA, one-way analysis of variance.
Fig. 3. Wild-type and R132H mutant idh1 restore pronephric marker expression in idh1-depleted Xenopus embryos. (A) WISH for atp1a1 showing pronephric structures in control embryos, idh1 morphants, and idh1 morphants co-injected with either wild-type (WT) idh1* mRNA or idh1*R132H mRNA. (B) Quantification of embryos exhibiting normal atp1a1 expression, based on intact staining intensity and normal pronephric morphology, as shown in (A). Both WT and R132H mRNA restored pronephric marker expression in idh1-depleted embryos (**p<0.01; one-way ANOVA followed by Dunnett’s multiple comparisons test). Scale bars: 500 μm. MO, morpholino oligonucleotide; WISH, whole-mount in situ hybridization; ANOVA, one-way analysis of variance.
