Prosaposin as a neurotrophic factor

Abstract

Prosaposin, saposin C and various peptide fragments of saposin C stimulate neurite outgrowth in vitro. In addition, prosaposin and saposin C promote increased myelination ex vivo. Prosaposin is present in large neurons of the brain, including both upper and lower motor neurons.

1 . A method for stimulating neural cell outgrowth or increased myelination, comprising:
 contacting neuronal cells with a composition comprising prosaposin or a fragment thereof having the ability to promote increased neural outgrowth or increased myelination activity.   
     
     
         2 . The method of  claim 1  wherein said prosaposin is native. 
     
     
         3 . The method of  claim 1  wherein said prosaposin is recombinantly produced. 
     
     
         4 . The method of  claim 1  wherein said fragment is saposin C. 
     
     
         5 . The method of  claim 1  wherein said fragment is a peptide comprising amino acids 8-29 of saposin C. 
     
     
         6 . The method of  claim 5  wherein said fragment consists essentially of the active neurotrophic fragment located within amino acids 8-29 of SEQ ID NO: 1. 
     
     
         7 . The method of  claim 1  wherein said neuronal cells are neuroblastoma cells. 
     
     
         8 . The method of  claim 7  wherein said neuroblastoma cells are selected from the group consisting of: NS20Y, Neuro 2A and N1E 115 cells. 
     
     
         9 . The method of  claim 1  wherein said neuronal cells are contacted in vitro. 
     
     
         10 . The method of  claim 1  wherein said neuronal cells are contacted in vivo. 
     
     
         11 . The method of  claim 1  wherein said cells are from mouse cerebellar explants. 
     
     
         12 . A method for treatment of demyelination disorders in a mammal comprising:
 identifying a mammal afflicted with said disorder;   and administering to said, mammal a pharmaceutically effective demyelination inhibiting amount of prosaposin or a neurotrophic fragment thereof.   
     
     
         13 . The method of  claim 12  wherein said fragment comprises saposin C. 
     
     
         14 . The method of  claim 12  wherein said demyelination disorder is selected from the group consisting of: multiple sclerosis, acute disseminated leukoencephalitis, progressive multifocal leukoencephalitis and adrenal leukodystrophy. 
     
     
         15 . The method of  claim 12  wherein said administration is selected from the group consisting of: intravenous, intramuscular, intradermal, subcutaneous, intracranial, intracerebrospinal and topical. 
     
     
         16 . The method of  claim 12  wherein said prosaposin or fragment thereof is administered in a biologically compatible carrier. 
     
     
         17 . The method of  claim 12  wherein said prosaposin or fragment thereof is enclosed in a lamellar structure. 
     
     
         18 . A method for halting or slowing the progress of neural or myelin degeneration in neural tissue, comprising:
 contacting neuronal tissue susceptible to such degradation with prosaposin or an active degradation-inhibiting fragment thereof.   
     
     
         19 . The method of  claim 18  wherein said fragment is saposin C. 
     
     
         20 . The method of  claim 18  wherein said tissue is in vitro. 
     
     
         21 . The method of  claim 18  wherein said tissue is in vivo. 
     
     
         22 . A method for the treatment of neuronal degenerative diseases of the central or peripheral nervous system, comprising administering to a mammal suffering from said disease an amount of a prosaposin fragment effective to retard or halt neuronal degeneration, wherein said fragment includes the neurotrophic activity of the peptide of SEQ ID NO:1. 
     
     
         23 . The method of  claim 22  wherein said administration is selected from the group consisting of: intravenous, intramuscular, intradermal, subcutaneous, intracranial, intracerebrospinal, topical and oral. 
     
     
         24 . The method of  claim 22  wherein said disease is a disease of the central nervous system and said fragment is selected to cross the blood brain barrier. 
     
     
         25 . The method of  claim 24  wherein said disease is selected from the group consisting of: Alzheimer's disease, Parkinson's disease, stroke, post-polio syndrome and amyotrophic lateral sclerosis. 
     
     
         26 . A method for retarding the progress of retinal neuropathy in a patient by administering to the patient an effective amount of prosaposin or a neurotrophic fragment thereof. 
     
     
         27 . The method of  claim 26  wherein said retinal neuropathy is macular degeneration and said patient is a human over the age of 65. 
     
     
         28 . The method of  claim 26  wherein said administration is selected from the group consisting of: topical, intravenous, intraocular and oral. 
     
     
         29 . A pharmaceutical composition comprising prosaposin or a neurotrophic fragment thereof in unit dosage form. 
     
     
         30 . A pharmaceutical composition comprising prosaposin or a neurotrophic fragment thereof formulated with a controlled release material. 
     
     
         31 . A neural prosaposin receptor protein in isolated or purified form. 
     
     
         32 . The receptor protein of  claim 31  wherein said receptor is isolated from a P100 plasma membrane fraction by affinity purification using a neurite growth-inducing peptide contained within the saposin C sequence linked to a solid support. 
     
     
         33 . The receptor protein of  claim 31  wherein said receptor has a molecular weight of approximately 20 kDa.