Search for putative gene regulatory motifs in CAHS3, linked to anhydrobiosis in a tardigrade Ramazzottius varieornatus, in vivo and in silico

• Published in: Genes to cells : devoted to molecular & cellular mechanisms 2024-12, Vol.29 (12), p.1144-1153
• Main Authors: Ishikawa, Sora, Tanaka, Sae, Arakawa, Kazuharu
• Format: Article
• Language: English
• Subjects: anhydrobiosis; Animals; Computer Simulation; Epidermis; Expression vectors; Gene expression; Gene Expression Regulation; Gene regulation; Original; Ramazzottius varieornatus; regulatory sequence; Tardigrada; Tardigrada - genetics; Tardigrada - metabolism; tardigrades
• ISSN: 1356-9597; 1365-2443; 1365-2443
• DOI: 10.1111/gtc.13168

Tardigrades possess the ability to enter an almost completely dehydrated state, anhydrobiosis. The CAHS (cytosolic abundant heat‐soluble) protein family has been identified as one of the anhydrobiosis‐related proteins. In particular, CAHS3 protein from an anhydrobiotic tardigrade, Ramazzottius varieornatus, shows heat‐solubility and reversible condensation and is one of the most highly expressed among the CAHS paralogs. A recently developed tardigrade‐specific vector showed tissue‐specific expression of RvCAHS3 most pronounced in the epidermis in vivo, contrary to the idea that anhydrobiotic genes are uniformly expressed in all tardigrade cells. In this study, we investigated the regulation of RvCAHS3 gene expression through in vivo expression experiments using tardigrade vectors with a series of truncated upstream regions coupled with in silico analysis to identify the anhydrobiosis‐related genes that are expressed under the same regulatory system as RvCAHS3. As a result, the 300–350 bp region upstream of RvCAHS3 is critical for regulating gene expression in tardigrade vector experiments, and three motifs conserved between two species of anhydrobiotic tardigrades were identified within a 500 bp region directly upstream of RvCAHS3 start codon. These motifs, which have also been identified upstream of other CAHS genes, could be associated with the regulatory system of anhydrobiosis‐related genes in tardigrades. Tardigrades can survive in an almost completely dehydrated state, known as anhydrobiosis, aided by proteins like CAHS3. Research using a newly developed tardigrade‐specific vector revealed that CAHS3 expression is most pronounced in the epidermis, suggesting tissue‐specific regulation rather than uniform expression. The study identified critical upstream regions and conserved motifs that likely regulate CAHS3 and other anhydrobiosis‐related genes in tardigrades.