Methods and compositions for treatment of forbes-cori disease

A nucleic acid construct, comprising a nucleotide sequence that encodes an AGL polypeptide, operably linked to a nucleotide sequence that encodes an internalizing moiety, wherein the nucleic acid construct encodes a chimeric polypeptide having AGL enzymatic activity and having the internalizing activity of the internalizing moiety.

A method of treating Forbes-Cori disease in a subject in need thereof, comprising administering to the subject an effective amount of a chimeric polypeptide comprising:

• (i) an AGL polypeptide, and (ii) an internalizing moiety;
• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of increasing glycogen debrancher enzyme activity in a cell, comprising contacting the cell with a chimeric polypeptide comprising:

• (i) an AGL polypeptide, and (ii) an internalizing moiety;
• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of delivering a chimeric polypeptide into a cell via an equilibrative nucleoside transporter (ENT2) pathway, comprising contacting a cell with a chimeric polypeptide, which chimeric polypeptide comprises (i) an AGL polypeptide, and (ii) an internalizing moiety that penetrates cells via ENT2;

• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

The method of any one of claims 110-1118, wherein the amino acid present at the amino acid position corresponding to any one of, or combination of, amino acid positions 220, 798, 814, 840, 928, 1033, 1237 and 1381 of SEQ ID NO:

• 1 is replaced with a proline in said AGL polypeptide.

A method of delivering a chimeric polypeptide into a muscle cell, comprising

• contacting a muscle cell with a chimeric polypeptide, which chimeric polypeptide comprises (i) an AGL polypeptide, and (ii) an internalizing moiety which promotes delivery into muscle cells;
• wherein the internalizing moiety promotes transport of the chimeric polypeptide into cells, and wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of delivering a chimeric polypeptide into a hepatocyte, comprising

• contacting a hepatocyte with a chimeric polypeptide, which chimeric polypeptide comprises (i) an AGL polypeptide or functional fragment thereof, and (ii) an internalizing moiety;
• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of increasing amyloglucosidase (AGL) enzymatic activity in a muscle cell, comprising contacting a muscle cell with a chimeric polypeptide, which chimeric polypeptide comprises (i) an AGL polypeptide, and (ii) an internalizing moiety;

• wherein the internalizing moiety promotes transport of the chimeric polypeptide into cells, and wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of increasing amyloglucosidase (AGL) enzymatic activity in a hepatocyte, comprising contacting a hepatocyte with a chimeric polypeptide, which chimeric polypeptide comprises (i) an AGL polypeptide or functional fragment thereof and (ii) an internalizing moiety;

• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

The method of any of claims 145-149, wherein said antibody or antigen binding fragment is monoclonal antibody 3E10, or a variant thereof that retains the cell penetrating activity of 3E10, or an antigen binding fragment of 3E10 or said 3E10 variant.

A chimeric polypeptide comprising:

• (i) an AGL polypeptide and (ii) an antibody or antigen binding fragment selected from:
• monoclonal antibody 3E10, or a variant thereof that retains cell penetrating activity, or a variant thereof that binds the same epitope as 3E10, or an antibody that has substantially the same cell penetrating activity as 3E10 and binds the same epitope as 3E10, or an antigen binding fragment of any of the foregoing;
• wherein the chimeric polypeptide has amylo-1,6-glucosidase activity and 4-alpha-glucotransferase activity.

A method of treating Forbes-Cori disease in a subject in need thereof, comprising contacting the cell with a chimeric polypeptide comprising:

• (i) a mature acid alpha-glucosidase (GAA) polypeptide and (ii) an internalizing moiety that promotes delivery into cells;
• wherein the chimeric polypeptide has acid alpha-glucosidase activity, and wherein the chimeric polypeptide does not comprise a GAA precursor polypeptide of approximately 110 kilodaltons.

A method of decreasing glycogen accumulation in cytoplasm of cells of a Forbes-Cori patient, comprising contacting muscle cells with a chimeric polypeptide, which chimeric polypeptide comprises (i) a mature acid alpha-glucosidase (GAA) polypeptide and (ii) an internalizing moiety that promotes transport into cytoplasm of cells;

• wherein the chimeric polypeptide has acid alpha-glucosidase activity, and wherein the chimeric polypeptide does not comprise a GAA precursor polypeptide of approximately 110 kilodaltons.

A method of increasing GAA activity in the cytoplasm of a cell, comprising delivering a chimeric polypeptide, wherein said chimeric polypeptide comprises:

• (i) a mature acid alpha-glucosidase (GAA) polypeptide and (ii) an internalizing moiety that promotes transport into cytoplasm of cells;
• wherein the chimeric polypeptide has acid alpha-glucosidase activity, and wherein the chimeric polypeptide does not comprise a GAA precursor polypeptide of approximately 110 kilodaltons.

The method of any of claims 200-227, wherein the chimeric polypeptide comprises a linker that conjugates or joins the mature GAA polypeptide to the internalizing moiety.

The method of any of claims 200-230, wherein the chimeric polypeptide is formulated with a pharmaceutically acceptable carrier.