Expression pattern and functional analysis of fundc1 in rare minnow (Gobiocypris rarus)

Fundc1 is a mitochondrial outer membrane protein and plays important roles in mitochondria fission and hypoxia-induced mitophagy in mammalian cells. However, there is no relevant report of fundc1 in fish. In the present study, we cloned a 942 bp fundc1 cDNA from rare minnow. The cDNA, designated as Grfundc1 cDNA, contains an open reading frame (ORF) of 459 bp which encodes a polypeptide of 152 amino acid residues. Comparisons of deduced amino acid sequences demonstrated that Grfundc1 was highly homologous with those of other vertebrates. RT-PCR and real time PCR detection revealed that the transcripts of Grfundc1 were not detectable in the unfertilized eggs and had high levels at blastula and gastrula stages. Whole mount in situ hybridization analysis observed that Grfundc1 was ubiquitously expressed at early stage and later riched in specific regions, such as brain, branchial arch, eye and somite during embryogenesis. Grfundc1 was expressed in all the tissues of rare minnow adult, including brain, liver, gill, eyes, heart, kidney, intestine, muscle, testis and ovary. The expression of Grfundc1 in the brain, gill, heart and eye of rare minnow adult was significantly down-regulated by hypoxia. Similar hypoxic response was observed in the rare minnow embryos at 48 hpf following hypoxia exposure. Functional analysis showed that knockdown of Grfundc1 significantly caused defects in the body axis and dorsal neural tissues of rare minnow embryos. These results indicate that Grfundc1 may play important roles in embryogenesis in fish.