Molecular cloning, characterization, and expression analysis of two GABAA receptor-associated proteins (GABARAP and GABARAPL2) from cephalopod Sepiella japonica.

BACKGROUND

GABAA receptor-associated proteins (GABARAPs) are evolutionarily conserved ubiquitin-like modulators known for their roles in γ-aminobutyric acid (GABA) receptor trafficking and autophagy. METHODS AND

RESULTS

In this research, two GABARAPs’ full-length cDNA sequences from the common Chinese cuttlefish Sepiella japonica (GABAA receptor-associated protein and GABAA receptor-associated protein like 2, SjGABARAP and SjGABARAPL2) were cloned and analyzed, with accession numbers PQ423738 and PQ423739, respectively. Both genes encode 117-amino-acid proteins, each containing a conserved ubiquitin-like domain typical of the autophagy-related protein 8 (ATG8) family. Sequence alignments and phylogenetic analysis confirmed that both proteins are highly conserved across invertebrates and vertebrates, with significant homology to GABARAP and GABARAPL2 from other species. Subcellular localization studies demonstrated that SjGABARAP and SjGABARAPL2 are primarily localized in the cytoplasm, and part of SjGABARAPL2 is also found in the nucleus. In situ hybridization revealed that both SjGABARAP and SjGABARAPL2 significant signals were notably observed in brain, optic lobe, and white body, with additional signals in pancreas of SjGABARAPL2. Furthermore, quantitative real-time PCR (qRT-PCR) analysis showed temporal and tissue-specific expression patterns, with high levels of SjGABARAPL2 in the pancreas, liver, gill, intestine, brain, and optic lobes.

CONCLUSIONS

These findings are expected to lay a basis for the next exploration of cell signaling and immune regulation of GABARAPs in S. japonica.