Abstract
Purpose:
To determine specific lipids associate with molecular motors such as Kif21B in neurons. To establish a method using fluorescent analogs of motor associated lipids as indicators of neuronal transport in retinal ganglion cells.
Methods:
Molecular motors (Kif21B, Dynein)-associated lipids in neurons were identified by immunoprecipitation and mass spectrometry using standardized class specific lipid identification settings. The lipids found associated with IP products of anti-motor antibody but not the control were selected and their fluorescent conjugates were obtained commercially. These fluorescent lipid analogs, e.g. that of a phosphatidylcholine (PC), were incubated with approximately 50,000 primary neurons in a microfluidic axon separation chamber. Fluorescent signals were recorded by time-lapse microscopy. The same lipid was tested in CD1 mouse optic nerve. All animal experiments were performed adhering to ARVO statement of use of animals in vision research.
Results:
Selected phosphatidylserine (PS) and PC species found associated with molecular motors were reproducible. A specific fluorescent PC but not a PS was found to be transported in the primary neurons. The PC showed increased fluorescence on loading and loss of fluorescence at some specific loci in the dendrites with simultaneous forward accumulation. The PS showed constant fluorescent signal and no movement once loaded on to the neuron membranes.. The same PC lipid was transported through the optic nerve in vivo.
Conclusions:
Specific lipids were identified to be bound with molecular motors. These lipids can be used as transport detectors in vivo and in vitro. These molecules could be used for probing neuronal transport blockage in diseases such as glaucoma.
Keywords: 496 detection •
583 lipids •
613 neuro-ophthalmology: optic nerve