Methods and compositions comprising tau oligomers

Abstract

Tau protein has a causative role in Alzheimer's disease and multiple other neurodegenerative disorders exhibiting tau histopathology collectively termed tauopathies. The primary function of tau protein is to facilitate assembly and maintenance of microtubules in neuronal axons. In the disease process tau protein becomes modified, loses its affinity to microtubules and accumulates in the cell body where it forms aggregates. The large neurofibrillary tangles formed from tau protein assembled into filaments were thought to be the pathological structure of tau. However, more recent work indicates that smaller, soluble oligomeric forms of tau are best associated with neuron loss and memory impairment. Here, novel compositions of tau oligomers and novel mechanisms for tau oligomer nucleation, extension and termination are taught. Methods for producing and purifying these structures for the development of small molecule and immunotherapeutics as well as antibodies for biomarkers of neurodegenerative diseases are taught.

What is claimed is: 
     
         1 . A composition comprising stabilized tau oligomer or a fragment or peptide derivative thereof. 
     
     
         2 . A composition according to  claim 1 , wherein (i) the tau oligomer is in at least one conformation comprising tau dimer, tau trimer, tau tetramer, tau pentamer, tau hexamer, tau septamer, tau octamer, tau nonamer, tau decamer, tau unadecamer, tau dodecamer, 3R tau, 4R tau, or mixtures of 3R tau and 4R tau or a fragment or peptide derivative thereof or a combination thereof; or (ii) the tau monomeric unit comprises one of SEQ ID NO. 1-6; or (iii) the tau oligomer is stable for at least 2 months; or (iv) the tau oligomer is substantially purified and/or isolated. 
     
     
         3 . A composition according to  claim 1 , wherein (i) the tau oligomer is in at least one conformation comprising tau dimer, tau trimer, tau tetramer, tau pentamer, tau hexamer, tau septamer, tau octamer, tau nonamer, tau decamer, tau unadecamer, tau dodecamer, 3R tau, 4R tau, or mixtures of 3R tau and 4R tau, or a combination thereof; or (ii) the tau monomeric unit comprises one of SEQ ID NO. 1-6; or (iii) the tau oligomer is stable for at least 2 months; or (iv) the tau oligomer is isolated. 
     
     
         4 . A composition according to  claim 2 , wherein (i) the tau oligomer is in at least a dimeric formation wherein each monomer has a peptide backbone with a N-terminal and C-terminal substantially parallel to each other in the dimeric form and a first tau monomer is covalently attached to a second tau monomer by an intermolecular disulfide linkage between an R2 cysteine 291 from the first tau monomer of SEQ ID NO. 6 and the R3 cysteine 322 from the second tau monomer of SEQ ID NO. 6 or (ii) the tau oligomer is in at least a dimeric formation wherein each monomer has a peptide backbone with a N-terminal and C-terminal substantially parallel to each other in the dimeric form and a first tau monomer is covalently attached to a second tau monomer by an intermolecular disulfide linkage between an R2 cysteine 291 from the first tau monomer of SEQ ID NO. 6 and the R3 cysteine 322 of SEQ ID NO. 6 from the second tau monomer, such that beta sheet forming hexapeptide regions (275vqiink280 in R2 and 306vqivyk401 in R3 of SEQ ID NO. 6) between two peptide backbones are aligned in parallel with a microtubule binding regions staggered. 
     
     
         5 . A composition according to  claim 2 , wherein the tau oligomer is in dimeric form and has at least two free thiol groups from each monomer, one from an R2 cysteine on a first tau monomer and one from an R3 cysteine on a second tau monomer. 
     
     
         6 . A composition according to  claim 2 , wherein the tau oligomer has microtubule binding regions and said regions are aligned out of phase such that R2 and R3 regions are able to bind via formation of a beta sheet and a disulfide linkage. 
     
     
         7 . A composition comprising tau oligomers according to  claim 2 , wherein the tau oligomers are formed by reacting tau 4R dimer and tau 4R/3R dimer with tau 4R monomer and tau 3R monomer to form tau trimer, tau tetramer, tau pentamer, tau hexamer, tau septamer, tau octamer, tau nonamer, tau decamer, tau unadecamer, tau dodecamer or a combination thereof. 
     
     
         8 . A composition according to  claim 1 , wherein (i) the tau peptide derivative comprises an aggregation core between R2 and R3 regions of two separate tau peptides, which comprises a primary aggregate forming region between a beta sheet forming region and two cysteines 291 and 322 of SEQ ID NO. 6 or (ii) the tau peptide derivative comprises an aggregation core between within 20 amino acids of R2 and within 20 amino acids of R3 regions of two separate tau peptides, which comprises a primary aggregate forming region between a beta sheet forming region and two cysteines 291 and 322 of SEQ ID NO. 6. 
     
     
         9 . A composition according to  claim 8 , wherein the tau peptide derivative is adapted to generate monoclonal or polyclonal antibodies that specifically bind to the peptide derivative or antigenic fragment thereof. 
     
     
         10 . A composition according to  claim 8 , wherein the tau peptide derivative is adapted to modulate an immune system of a mammal suffering from Alzheimer's disease. 
     
     
         11 . A composition according to  claim 8 , wherein the tau peptide derivative is adapted for use as an immunotherapeutic agent for treatment of one or more tauopathies. 
     
     
         12 . A composition according to  claim 1 , wherein the purified and stabilized tau oligomer is adapted to generate monoclonal or polyclonal antibodies that bind specifically to the purified and stabilized tau oligomer when administered to a mammal. 
     
     
         13 . A composition according to  claim 1 , wherein the purified and stabilized tau oligomer comprises an aggregation core between an R2 and R3 region of two separate tau peptides, said tau peptides having no free thiol moieties. 
     
     
         14 . A composition according to  claim 1 , wherein the purified and stabilized tau oligomer comprises tau oligomers bound by disulfide linkages between R2 and R3 regions of tau oligomers or R3 and R3 regions of tau oligomers and the composition is adapted for screening drug compounds that enhance or inhibit tau oligomer formation. 
     
     
         15 . A composition according to  claim 1 , wherein the purified and stabilized tau oligomer comprises tau oligomers bound by disulfide linkages between R2 and R3 regions of tau oligomers or R3 and R3 regions of tau oligomers and the composition is a biomarker for Alzheimer's disease progression or tauopathy disease progression. 
     
     
         16 . A composition comprising an immunotherapeutic agent that specifically binds to extracellular tau oligomer in a mammal. 
     
     
         17 . A composition comprising a substantially purified and stabilized tau oligomer or a fragment or peptide derivative thereof for use as an immunotherapeutic agent, wherein the substantially purified and stabilized tau oligomer is adapted for passive or active immunotherapy. 
     
     
         18 . A composition according to  claim 14 , wherein the drug compounds prevents or inhibits tau-tau binding resulting from hydrogen bonding, van der Waals interaction such that disulfide bond formation is blocked or prevented.