Structural Conservation and Transcriptional Plasticity of atp2a1 in Acrossocheilus fasciatus Under Temperature and Flow Acclimation.

BACKGROUND/

OBJECTIVES

The sarcoplasmic reticulum Ca2+-ATPase 1 (Atp2a1) is a key regulator of calcium homeostasis and muscle relaxation, yet its roles in fish remain poorly understood.

METHODS

We investigated the structural characteristics, phylogenetic relationships, and transcriptional regulation of atp2a1 in Acrossocheilus fasciatus, a stream-dwelling cyprinid sensitive to environmental fluctuations.

RESULTS

Bioinformatic analyses revealed that the 991-aa Atp2a1 protein is highly conserved among teleosts but exhibits divergence from mammals in the Cation_ATPase_N domain and transmembrane regions TM3, TM9, and TM10. Phylogenetic analysis clustered A. fasciatus most closely with Onychostoma macrolepis. Tissue-specific qRT-PCR demonstrated predominant expression in skeletal muscle, followed by testis, brain, heart, and gill. Promoter prediction identified binding motifs for KLF9, CTCF, MAZ, KLF5, ONECUT3, and HOXB13. qRT-PCR analysis showed that long-term cold acclimation (16 °C vs. 24 °C) markedly downregulated atp2a1 expression (ANOVA, p < 0.05, n = 3), whereas moderate flow velocity (2 BL·s-1 vs. 0 BL·s-1) significantly upregulated it (ANOVA, p < 0.05, n = 3). Alternative splicing analysis based on RNA-seq data further revealed a corresponding decrease and increase in skipped exon (SE) inclusion under cold and flow conditions, respectively (Padj < 0.05).

CONCLUSIONS

These results further raise the possibility that the regulatory complexity of atp2a1 contributes to adaptation of teleosts under fluctuating environments.