Targeted therapeutic proteins

Abstract

Targeted therapeutics that localize to a specific subcellular compartment such as the lysosome are provided. The targeted therapeutics include a therapeutic agent and a targeting moiety that binds a receptor on an exterior surface of the cell, permitting proper subcellular localization of the targeted therapeutic upon internalization of the receptor. Nucleic acids, cells, and methods relating to the practice of the invention are also provided.

We claim: 
     
         1 . A targeted therapeutic comprising:
 a therapeutic agent that is therapeutically active in a mammalian lysosome; and means for binding an extracellular domain of human cation-independent mannose-6-phosphate receptor in a mannose-6-phosphate-independent manner.   
     
     
         2 . The targeted therapeutic of  claim 1 , wherein the means for binding comprises retinoic acid or a derivative thereof. 
     
     
         3 . The targeted therapeutic of  claim 1 , wherein the means for binding comprises a protein having an amino acid sequence at least 70% identical to a domain of urokinase-type plasminogen activator receptor. 
     
     
         4 . The targeted therapeutic of  claim 1 , wherein the means for binding comprises IGF-II or an antibody variable domain. 
     
     
         5 . (canceled) 
     
     
         6 . The targeted therapeutic of  claim 1 , wherein the means for binding binds to the extracellular domain with a submicromolar dissociation constant at about pH 7.4 
     
     
         7 .- 9 . (canceled) 
     
     
         10 . The targeted therapeutic of  claim 6 , wherein the dissociation constant is between 10 −7  M and 10 −11  M. 
     
     
         11 . The targeted therapeutic of  claim 6 , wherein the means for binding binds to the extracellular domain with an dissociation constant at about pH 5.5 at least ten times the dissociation constant at about pH 7.4. 
     
     
         12 .- 36 . (canceled) 
     
     
         37 . A therapeutic fusion protein comprising:
 a therapeutic domain and   a subcellular targeting domain that binds to an extracellular domain of a receptor on an exterior surface of a cell and, upon internalization of the receptor, permits localization of the therapeutic domain to a subcellular compartment where the therapeutic domain is therapeutically active.   
     
     
         38 . The therapeutic fusion protein of  claim 37 , wherein the subcellular compartment is selected from the group consisting of a lysosome, an endosome, endoplasmic reticulum, and golgi complex. 
     
     
         39 . The therapeutic fusion protein of  claim 38 , wherein the subcellular compartment is a lysosome. 
     
     
         40 . (canceled) 
     
     
         41 . The therapeutic fusion protein of  claim 37 , wherein the therapeutic domain has a therapeutic enzymatic activity. 
     
     
         42 . The therapeutic fusion protein of  claim 41 , wherein a cellular or subcellular deficiency in the enzymatic activity is associated with a human disease. 
     
     
         43 . The therapeutic fusion protein of  claim 42 , wherein the human disease is a lysosomal storage disease. 
     
     
         44 . A nucleic acid encoding the therapeutic fusion protein of  claim 37 . 
     
     
         45 . A cell comprising the nucleic acid of  claim 44 . 
     
     
         46 . A method of producing a therapeutic fusion protein, the method comprising the step of providing to the cell of  claim 45  conditions permitting expression of the therapeutic fusion protein. 
     
     
         47 .- 49 . (canceled) 
     
     
         50 . A method of treating a patient, the method comprising administering to the patient the therapeutic fusion protein of  claim 37 . 
     
     
         51 . A method of treating a patient, the method comprising administering to the patient the nucleic acid of  claim 44 . 
     
     
         52 . A method of treating a patient, the method comprising administering to the patient the cell of  claim 45 . 
     
     
         53 . A method of treating a patient, the method comprising:
 (i) synthesizing a targeted therapeutic comprising a therapeutic agent that is therapeutically active in a mammalian lysosome and a targeting moiety that binds human cation-independent mannose-6-phosphate receptor in a mannose-6-phosphate-independent manner; and   (ii) administering the targeted therapeutic to the patient.   
     
     
         54 .- 57 . (canceled)