Multiple functions of FADD in apoptosis, NF‐κB‐related signaling, and heart development in Xenopus embryos

Abstract

FADD is an adaptor protein that transmits apoptotic signals from death receptors. Additionally, FADD has been shown to play a role in various functions including cell proliferation. However, the physiological role of FADD during embryonic development remains to be delineated. Here, we show the novel roles FADD plays in development and the molecular mechanisms of these roles in Xenopus embryos. By whole-mount in situ hybridization and RT-PCR analysis, we observed that fadd is constantly expressed in early embryos. The upregulation or downregulation of FADD proteins by embryonic manipulation resulted in induction of apoptosis or size changes in the heart during development. Expression of a truncated form of FADD, FADDdd, which lacks pro-apoptotic activity, caused growth retardation of embryos associated with dramatic expressional fluctuations of genes that are regulated by NF-jB. Moreover, we isolated a homolog of mammalian cullin-4 (Cul4), a component of the ubiquitin E3 ligase family, as a FADDdd-interacting molecule in Xenopus embryos. Thus, our study shows that FADD has multiple functions in embryos; it plays a part in the regulation of NF-jB activation and heart formation, in addition to apoptosis. Furthermore, our findings provide new insights into how Cul4-based ligase is related to FADD signaling in embryogenesis.

Transgenic Xenopus laevis for live imaging in cell and developmental biology

“…data, 2012), which is thought to be involved in the thinning of the ectoderm and the subsequent mouth opening, can be monitored by SCAT3, confirming data obtained earlier using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method (Dickinson & Sive 2006). Furthermore, we have used the transgenic embryos to verify the function of a recently identified Xenopus homologue of human FADD, and confirmed its strong pro-apoptotic activity by detecting the cleavage of SCAT3, namely the caspase-3 activation in developing embryos (Sakamaki et al 2012). Thus, this established transgenic frog line is useful for analyzing apoptosis in live animals.…”

“…Furthermore, we have used the transgenic embryos to verify the function of a recently identified Xenopus homologue of human FADD, and confirmed its strong pro‐apoptotic activity by detecting the cleavage of SCAT3, namely the caspase‐3 activation in developing embryos (Sakamaki et al . ). Thus, this established transgenic frog line is useful for analyzing apoptosis in live animals.…”

Functional conservation of the apoptotic machinery from coral to man: the diverse and complex Bcl-2 and caspase repertoires of Acropora millepora

“…A third plasmid construct, pCAGGS-p35, which contains the baculovirus p35 gene encoding a pan-caspase inhibitor protein, was generated previously [ 48 ]. Generation of the plasmid construct pCAG-mCherry used for the detection of transfected cells was previously described [ 49 ]. Likewise, generation of the pCS2-tXlBid plasmid has previously been described [ 31 ]; this allows expression of tXlBid, the pro-apoptotic truncated version of the Xenopus Bid protein, in cultured mammalian cells.…”

Functional characterisation of Holothuria leucospilota Fas-associated death domain in the innate immune-related signalling pathways

“…7 To date, a number of reports regarding the activation of the innate immune-related signalling pathways by FADD have been published. [6][7][8][9][10][11][12][13] The activation of NF-jB by FADD has been reported in mammals and other vertebrates. [6][7][8][9][10][11] In mammalian cells, the activation of transcription factor IFN regulatory factor-3 (IRF-3) by FADD has been found and is supposed to be involved in the antiviral effect of FADD.…”