On the Mechanisms Underlying the Secretion and Export of TranslationallyControlled Tumor Protein/Histamine Releasing Factor (TCTP/HRF)

摘要

Numerous studies have demonstrated that TCTP/HRF is a unique cytokine, modulating the release ofinflammatory mediators from various cell types including cells involved in allergic phenomena. Despite the absence of aleader sequence in its NH2-terminus, TCTP/HRF is regarded as a secreted protein found outside of cells as well as influids from allergic patients and parasitic organisms. Recent studies clarified several potential mechanisms leading to itssecretion. For example, these studies showed that TCTP/HRF is exported from cells via a non-classical, endoplasmicreticulum (ER)/Golgi-independent mechanism associated with exosomal transport. TSAP6, a p53-inducibletransmembrane protein, has been shown to enhance exosome production, and facilitate the secretion of TCTP/HRF intoextracellular milieu. Additionally, H,K-ATPase also appears to play a role in the transport of TCTP/HRF, since inhibitorsof H,K-ATPase also inhibit TCTP/HRF exit. The exact mechanisms involved in TCTP/HRF secretion has not yetemerged. Here we attempted to collate the available information in the current understanding of the mechanismsunderlying the release of TCTP/HRF and of the factors that seem to influence these mechanisms.