IDS transfer from overexpressing cells to IDS-deficient cells

Area of Science:

• Biochemistry
• Cell Biology
• Genetics

Background:

• Mucopolysaccharidosis type II (MPS II), or Hunter syndrome, is a rare X-linked lysosomal storage disease caused by iduronate sulfatase (IDS) deficiency.
• Understanding enzyme transfer mechanisms is crucial for developing effective therapies for lysosomal storage diseases.

Purpose of the Study:

• To investigate the capacity of cells overexpressing IDS to transfer the enzyme to IDS-deficient cells.
• To compare IDS processing in different cell types and analyze the efficiency of enzyme transfer via cell-free medium versus coculture.

Main Methods:

• Comparative analysis of IDS processing steps in fibroblasts, COS cells, and lymphoblastoid cell lines.
• Testing IDS transfer to IDS-deficient cells using cell-free medium from overexpressing cells and coculture methods.
• Utilizing transfected L beta cells and deleted fibroblasts for coculture experiments to assess endocytosis and enzyme transfer.

Main Results:

• Identical IDS precursor (76 and 90 kDa) to mature (55 and 45 kDa) polypeptide processing was observed across fibroblasts, COS cells, and lymphoblastoid cell lines.
• IDS transfer to deficient cells occurred preferentially via cell-to-cell contact, with limited secretion of precursors.
• Transferred IDS polypeptides were correctly processed to mature forms when transfer occurred via cell-to-cell contact, but not when internalized from the medium.

Conclusions:

• Cell-to-cell contact is the primary mechanism for functional IDS transfer to deficient cells.
• While transferred IDS can be correctly processed, mistargeting of precursors may hinder maturation in recipient cells.
• These findings highlight the importance of cell-mediated delivery for potential gene therapy approaches in MPS II.