In response to environmental stresses, such as heat shock, oxidative stress, and viral infection, arrest of translation initiation reduces energy-expensive cellular processes and conserves the energy required for the repair of cellular damage. Untranslated mRNAs that accumulate in these cells move to discrete cytoplasmic foci known as stress granules (SGs). SGs are characterized by the presence of translational initiation factors such as eIF4E, eIF4G, eIF4A, eIF4B, eIF3, eIF2, poly(A)-binding protein, and stalled 40S ribosomal units. The best-known proteins integral to SG formation are T-cell intracellular antigen (TIA) proteins, which are considered robust markers of SGs. The assembly of SGs, one of the most important post-transcriptional mechanisms, helps cells to survive under adverse environmental conditions. Currently, there is no information on the cell-protective roles of SGs in marine invertebrates under environmental stress. In the present study, we hypothesized that TIA-1, an mRNA-binding protein that can aggregate within granules, may play a significant role in the sea cucumber in response to heat stress. We characterized the amino sequence of TIA-1. The full-length cDNA of TIA-1 is 3108 bp, comprising a 5'-untranslated region (UTR) of 16 bp, 3'-UTR of 1808 bp, and open reading frame (ORF) of 1284 bp. The ORF encodes 427 amino acids, with a calculated molecular mass of 48.07 kD and 6.19 theoretical isoelectric point. Structural analysis showed that TIA-1 has three N-terminal RNA-recognition motifs and two C-terminal low-complexity regions, which are related to prion proteins and have the capacity to form reversible aggregates. Phylogenetic analyses revealed that TIAR. Moreover, we detected whole-cell and subcellular protein expression levels of TIA-1 by using western blotting. The localization of TIA-1 to subnuclear structures was assessed using immunofluorescence analysis. The results showed that the expression level of TIA-1 in cytoplasmic fractions under heat stress (25℃) was significantly increased when compared with the control group (15℃). The fluorescence signals of TIA-1 were observed to be translocated from the nucleus to the cytoplasm in response to heat stress, which suggests that TIA-1 may be involved in the formation of SGs to protect the stressed intestinal cells of under high temperature conditions. We identified a potential novel cytoprotective mechanism in response to heat stress in from the viewpoint of post-transcriptional regulation, which may play an important role in reducing the translational rates and/or mRNA processing under unfavorable environmental conditions in marine invertebrates.