Mammalian expression systems

An expression system comprising genetically-engineered mammalian cells, each of which includes one or more recombinant expression cassettes encoding a protein of interest and a constitutively-active component of an FGFR-1-mediated signal transduction pathway.

An expression system comprising mammalian host cells cultured in a medium, wherein each said cell comprises a recombinant expression cassette encoding a protein of interest, and said protein of interest is incapable of interacting with cell-surface heparan sulfate proteoglycans to induce cellular internalization of said protein, and wherein said medium comprises an effective amount of an FGFR-1 agonist for increasing the production of said protein by said cells.

An expression system comprising mammalian host cells cultured in a medium, wherein each said cell comprises a recombinant expression cassette encoding a protein of interest, and said medium comprises an effective amount of β-xyloside for increasing the production of said protein by said cells.

The method of 18, wherein the protein is not a viral protein.

An expression system comprising mammalian host cells cultured in a medium, wherein each said cell comprises a recombinant expression cassette encoding a protein of interest, and said protein of interest is incapable of interacting with cell-surface heparan sulfate proteoglycans to induce cellular internalization of said protein, and wherein said medium comprises an effective amount of heparin for increasing the production of said protein by said cells, wherein the effective amount is (i) greater than 10 μg/ml and less than 100 μg/ml, and (ii) greater than 100 μg/ml and less than or equal to 1,000 μg/ml.

A method of treating a disease, comprising administering a therapeutically effective amount of a protein to a patient, (a) wherein the protein is produced according to a method comprising the steps of (i) culturing mammalian cells comprising a messenger RNA encoding the protein, and (ii) activating FGFR-1;

• (b) wherein activation of FGFR-1 enhances translation of the recombinantly-expressed protein;
• and (c) wherein the protein itself is not capable of activating FGFR-1.

A method of providing protection against a disease, comprising administering a prophylactically effective amount of a protein to a patient, (a) wherein the protein is produced according to a method comprising the steps of (i) culturing mammalian cells comprising a messenger RNA encoding the protein, and (ii) activating FGFR-1;

• (b) wherein activation of FGFR-1 enhances translation of the recombinantly-expressed protein;
• and (c) wherein the protein itself is not capable of activating FGFR-1.

A method for producing a protein, comprising (a) culturing mammalian cells in a medium, each said cell comprising one or more recombinant expression cassettes encoding said protein, and the medium comprising heparin or heparan sulfate, wherein the heparin is at a concentration of either (i) greater than 10 μg/ml and less than 100 μg/ml, or (ii) greater than 100 μg/ml and less than or equal to 1,000 μg/ml;

• (b) expressing said protein and said component in said cells;
• and (c) isolating said protein from said cells or medium.