Rational discovery of testosterone-enhancing peptide (AGNYGLPT) from sea cucumber: targeting T-type calcium channels...

Calcium ions (Ca²⁺) are a crucial signaling factor in testosterone synthesis. This study employed computer-guided peptide screening and mechanism exploration to elucidate how sea cucumber peptide (SCP) promotes testosterone synthesis via Cacna1g (T-type calcium channel). Ca²⁺ treatment alone significantly upregulated the expression of Cacna1g, protein kinase C (PKC), protein kinase A (PKA), and testosterone synthase genes (StAR, Hsd17b3, Cyp17a1); these effects were further enhanced by SCP co-treatment. Molecular docking combined with correlation analysis pinpointed the peptide's isoelectric point as a critical determinant governing its binding affinity to Cacna1g. SCP was subsequently fractionated into three components via ion-exchange chromatography, among which the fraction 1 (F1) elevated intracellular Ca²⁺ levels and enhanced testosterone synthesis. Moreover, molecular docking results for the F1 sequences also showed a positive linear relationship between binding affinity and isoelectric point. Peptide AGNYGLPT in F1 stabilizes Cacna1g (with the strongest binding ability) via hydrogen bonding, and participates in ion channel formation (Charge = -2, Radius = 2.8 Å). In vitro, AGNYGLPT increased intracellular Ca²⁺ levels and enhanced testosterone synthesis, but this effect was abolished by inhibition of T-type calcium channels. This study provided mechanistic insights into peptide-channel interactions and offered new ideas for computer-assisted screening of active peptides.