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Mol Cell Biol September 1, 2007; 27 (18): 6420-32.

The mitochondrial respiratory chain controls intracellular calcium signaling and NFAT activity essential for heart formation in Xenopus laevis.

Chen Y , Yuen WH , Fu J , Huang G , Melendez AJ , Ibrahim FB , Lu H , Cao X .

The mitochondrial respiratory chain (MRC) plays crucial roles in cellular energy production. However, its function in early embryonic development remains largely unknown. To address this issue, GRIM-19, a newly identified MRC complex I subunit, was knocked down in Xenopus laevis embryos. A severe deficiency in heart formation was observed, and the deficiency could be rescued by reintroducing human GRIM-19 mRNA. The mechanism involved was further investigated. We found that the activity of NFAT, a transcription factor family that contributes to early organ development, was downregulated in GRIM-19 knockdown embryos. Furthermore, the expression of a constitutively active form of mouse NFATc4 in these embryos rescued the heart developmental defects. NFAT activity is controlled by a calcium-dependent protein phosphatase, calcineurin, which suggests that calcium signaling may be disrupted by GRIM-19 knockdown. Indeed, both the calcium response and calcium-induced NFAT activity were impaired in the GRIM-19 or NDUFS3 (another complex I subunit) knockdown cell lines. We also showed that NFAT can rescue expression of Nkx2.5, which is one of the key genes for early heart development. Our data demonstrated the essential role of MRC in heart formation and revealed the signal transduction and gene expression cascade involved in this process.

PubMed ID: 17636012
PMC ID: PMC2099623
Article link: Mol Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: ndufa13 ndufs3 nfatc2 nfatc4 nkx2-5 ppp3ca
GO keywords: calcineurin-mediated signaling
Morpholinos: ndufa13 MO1 ndufa13 MO2

References [+] :
Angell, Identification of GRIM-19, a novel cell death-regulatory gene induced by the interferon-beta and retinoic acid combination, using a genetic approach. 2000, Pubmed