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Insulin-like growth factor II peptide fusion enables uptake and lysosomal delivery of α-N-acetylglucosaminidase to mucopolysaccharidosis type IIIB fibroblasts.
Biochem J. 2013 Nov 25. [Epub ahead of print] doi:
Kan SH, Troitskaya LA, Sinow CS, Haitz K, Todd AK, Di Stefano A, Le SQ, Dickson PI, Tippin BL
Abstract:
.....We expressed and characterized a modified, recombinant human NAGLU fused to the receptor binding motif of insulin-like growth factor-II (rhNAGLU-IGF-II) to enhance its ability to enter cells using the cation-independent mannose 6-phosphate receptor, which is also the receptor for IGF-II (at a different binding site). RhNAGLU-IGF-II was stably expressed in Chinese hamster ovary cells, secreted and purified to apparent homogeneity. The Km and pH optimum of the fusion enzyme was similar to those reported for rhNAGLU.
Both intracellular uptake and confocal microscopy suggested MPS IIIB fibroblasts readily take up the fusion enzyme via receptor-mediated endocytosis that was significantly inhibited (p<0.001) by monomeric IGF-II peptide. Glycosaminoglycan storage was reduced by 60% (p<0.001) to near background levels in MPS IIIB cells after treatment with rhNAGLU-IGF-II, with half-maximal correction at concentrations of 3-12 pM
. Similar cellular uptake mechanism via the IGF-II receptor was also demonstrated in two different brain tumor-derived cell lines.....
Both intracellular uptake and confocal microscopy suggested MPS IIIB fibroblasts readily take up the fusion enzyme via receptor-mediated endocytosis that was significantly inhibited (p<0.001) by monomeric IGF-II peptide. Glycosaminoglycan storage was reduced by 60% (p<0.001) to near background levels in MPS IIIB cells after treatment with rhNAGLU-IGF-II, with half-maximal correction at concentrations of 3-12 pM
. Similar cellular uptake mechanism via the IGF-II receptor was also demonstrated in two different brain tumor-derived cell lines.....
PMID: 24266751
Free Full-Text: http://www.biochemj.org/bj/imps/refer.htm?MSID=BJ20130845
Tags: GILT, IGF-2, lysosomal targeting