Interactions between the recombinant human CREG protein and cathepsins and M6P/IGFIIR / 中国组织工程研究

ABSTRACT

BACKGROUND:It has been found that cel ular repressor of E1A-stimulated genes (CREG) is a lysosomal protein binding directly to the mannose-6-phosphate (M6P)/insulin-like growth factor II receptor (IGFIIR) and depends on the interaction with M6P receptors for efficient delivery to lysosomes OBJECTIVE:To study the interactions between the exogenous CREG protein and cathepsins and M6P/IGFIIR and to confirm the effect of CREG protein on expression and distribution of M6P/IGFIIR. METHODS:Double-stained immunofluorescence and coimmunoprecipitation were applied to observe the interactions between the exogenous CREG protein and cathepsin B, cathepsin L and M6P/IGFIIR. Using gain-of-function and loss-of-function approaches, the effect of CREG on expression and distribution of M6P/IGFIIR were studied by western blot assay and immunofluorescence staining. RESULTS AND CONCLUSION:Double-stained immunofluorescence and coimmunoprecipitation analyses confirmed the direct interactions between the exogenous CREG protein and cathepsin B, cathepsin L and M6P/IGFIIR. It was verified that CREG plays a critical role not in the expression but in the distribution of M6P/IGFIIR using gain-of-function and loss-of-function approaches. These findings provide evidence that exogenous CREG protein is located in lysosomes and has interactions with cathepsins and M6P/IGFIIR, also CREG plays a critical role in the distribution of M6P/IGFIIR.