MOLECULAR MECHANISMS OF SIGNAL TRANSDUCTION IN RETINA

DESCRIPTION: The goal of the laboratory is to
better understand the molecular mechanisms of neural processing in the
retina. It is known that the segregation of light stimuli into ON and OFF
pathways is done at the level of the bipolar cells. Since it is thought
that photoreceptor cells release glutamate as a neurotransmitter, the
functional difference between ON and OFF bipolar cells is proposed to be
the result of their expressing distinct glutamate receptors. Specifically
this proposal aims to explore the relationship between the expression of
different glutamate receptors and the diversity of bipolar cells in the
mouse retina. 1.Glutmate receptors in OFF bipolar cells. The diversity and distribution
of glutamate receptor subunits will be examined in OFF bipolar cells by in
situ hybridization and immunonohistochemical analyses of horizontal and
vertical retinal sections and dissociated retinal cells. Glutamate receptor
subunit expression in electrophysiologically identified individual OFF
bipolar cells will be determined using the PCR technique. 2.Glutamate receptors in ON bipolar cells. The APB-type glutamate
receptor, which is thought to mediate the sign inversion in ON bipolar
cells, will be cloned. Antibodies will be raised against fragments of the
APB receptor expressed in bacteria. The diversity and distribution of
glutamate receptors will be examined in ON bipolar cells by in situ
hybridization and immunohistochemical analyses of horizontal and vertical
retinal sections and dissociated retinal cells. Glutamate receptor
expression in electrophysiologically identified individual ON bipolar cells
will be analyzed using the PCR technique. 3.Glutamate receptors during development. Studies have shown an early
exrpession of neurotransmitter receptors in the developing brain,
suggesting some role in the establishment of neural circuitry. The
regulation of glutamate receptor expression in relation to the
differentiation of bipolar cells will be analyzed using in situ
hybridization and immunohistochemistry. The research proposed here will provide the basis with which to analyze the
expression of glutamte receptors in mice with retinal degenerations and to
assess the effects of receptor alterations during development and in the
adult retina using transgenic mice.