In-depth profiles of bioactive large molecules in saliva secretions of leeches determined by combining salivary gland proteome and transcriptome data

Abstract

Medicinal leeches have been widely utilized in medical procedures for thousands of years. The application of leeches depends on the components of leech saliva secretions and active molecules, but many components of the secretions are not well characterized due to their low concentration and abundance. Determination of the profiles of leech salivary secretions is important to its medicinal application. In this study, we performed an in-depth proteomic analysis of leech salivary glands and deduced 434 full-length protein sequences from combined leech proteome and transcriptome databases. After integrating data from both datasets, forty-four proteins and two hundred twenty-one transcripts of bioactive molecules were involved in leech sucking pathways. Using gene expression analysis, we found that two-thirds of bioactive genes played key roles in leech bite processes and were associated cave-dwelling habitats. Our results indicate that the treatment efficiency can differ depending on the sucking leech species. Moreover, combining high-throughput proteomic and transcriptomic analyses is effective for the determination of wide profiles of proteins that are present at low concentrations in secretions. These findings highlight the extensive diversity of bioactive molecules and provide a new foundation for performing novel investigations and discovering future pharmacological agents or targets in leech medicinal therapy. SIGNIFICANCE: Medicinal leech therapy has been used for many centuries depending on the components of leech saliva secretions and active actions, but many components of the secretions were less known due to its low concentration and abundance. Determination of the profiles of leech salivary secretions is important to its medicinal application. Hereby, the molecular information provided by proteomic and transcriptomic analysis can be used to develop a more thorough understanding of leech sucking pathway and medicinal application. It provided a new foundation for performing novel investigations and discovering future pharmacological agents or targets in leech medicinal therapy.

Keywords: Leech; Leech sucking pathways; Medicinal leech therapy; Proteomic; Salivary secretions.