COMPOSITIONS AND METHODS OF TREATMENT USING MODULATORS OF MOTONEURON DISEASES
The invention disclosed herein describes a novel therapeutic target for motoneuron diseases (altered dynamics of microtubules in neurons); methods for measuring the state of activity of this therapeutic target in subjects with established, incipient, or potential motoneuron disease; the discovery of drug agents that modulate neuronal microtubule dynamics in living subjects with motoneuron diseases; the discovery that administration of such agents, alone or in combinations, can improve MT-mediated transport of “synaptic vesicle cargo” molecules along and through axons; the discovery that such modulation of altered microtubule dynamics and improvement in MT-transport of molecules along axons can provide marked neuroprotective therapy for living subjects with motoneuron diseases, including delay in symptoms and prolongation of survival; and the discovery that monitoring of neuronal microtubule dynamics in response to therapeutic interventions in subjects with motoneuron diseases, allows diagnostic monitoring, to optimize therapeutic regimens and treatment strategies in individual subjects or in drug trials. The monitoring involves measuring isotope enrichment in secreted synaptic vesicle cargo molecules.
1 . A method of monitoring the effects of an agent in subjects with a motoneuron disease, comprising:
a) exposing a test living system to one or more agents;
b) administering an isotope-labeled substrate to said living system for a period of time sufficient for said isotope-labeled substrate to enter into one or more cargo molecules in axons of motor neurons;
c) obtaining a plurality of samples from said living system;
d) quantifying the time course, pattern or amount of isotopic enrichment in secreted synaptic vesicle cargo molecules from said plurality of samples;
e) measuring the time course, pattern or amount of isotopic enrichment in secreted synaptic vesicle cargo molecules in a sample from a control system;
f) comparing the time course, pattern or amount of isotopic enrichment in said isolated synaptic vesicle cargo molecules in said living system to the same parameters in a control living system; and
g) determining the effect of said agent on the rate of microtubule (MT)-mediated slow and fast axonal transport in motor neurons.
2 . The method of claim 1 , wherein the secreted synaptic vesicle cargo molecules are selected from the group consisting of growth factors, neurotransmitters, glycoprotein, and secreted enzymes.
3 . The method of claim 2 , wherein said growth factors comprise neuregulins-1, said neurotransmitters comprise acetylcholine, said glycoprotein comprises chromogranin B, and said secreted enzymes comprise acetylcholinesterase.
4 . The method according to claim 1 , wherein the time course, pattern or amount of isotopic enrichment in secreted synaptic vesicle cargo molecules, and thereby the efficiency of MT-mediated axonal transport, in motor neurons from said test living system is compared to the time course, pattern or amount of isotopic enrichment in secreted cargo molecules, and thereby the efficiency of fast axonal transport, in motor neurons from said control living system.
5 . The method according to claims 1 - 4 , wherein a plurality of agents is administered alone or in combination.
6 . The method according to claims 1 - 5 wherein said samples comprise CSF, blood or tissue samples.
7 . The method according to claims 1 - 6 wherein said samples are collected at multiple time points.
8 . A method of treating a motoneuron disease comprising administering an agent that alters the efficiency of MT-mediate slow and fast axonal transport in motor neurons, whereby said motoneuron disease is treated.
9 . A method of screening for agents effective in motoneuron disease comprising contacting neurons with an agent that alters the efficiency of MT-mediated slow and fast axonal transport in motor neurons