Activity-Dependent Expression of Acyl-Coenzyme A-Binding Protein in Retinal Muller Glial Cells Evoked by Optokinetic Stimulation

Abstract

Long-term horizontal optokinetic stimulation (HOKS) decreases the gain of the horizontal optokinetic reflex and evokes the second phase of optokinetic afternystagmus (OKAN-II). We investigated the possible molecular constituents of this adaptation. We used a differential display reverse transcriptase-PCR screen for mRNAs isolated from retinas of rabbits that received HOKS. In each rabbit, we compared mRNAs from the retina stimulated in the posterior3anterior (preferred) direction with mRNAs from the retina stimulated in the anterior3posterior (null) direction. Acyl-CoA-binding protein (ACBP) mRNA was one of four mRNAs selected by this screen, the proteins of which interact with GABA receptors. HOKS in the preferred direction increased ACBP mRNA transcription and ACBP protein expression. ACBP was localized to Muller glial cells by hybridization histochemistry and by immunohistochemistry. ACBP interacts with the ␣ 1 -subunit of the GABA A receptor, as determined by a yeast two-hybrid technique. This interaction was confirmed by coimmunoprecipitation of ACBP and the ␣ 1 -subunit of the GABA A receptor using an antibody to GABA A ␣ 1 . The interaction was also confirmed by a "pull-down" assay in which histidine-tagged ACBP was used to pull down the GABA A ␣ 1 . ACBP does not cross the blood-brain barrier. However, smaller truncated proteolytic fragments of ACBP do, increasing the excitability of central cortical neurons.Muller cells may secrete ACBP in the inner plexiform layer, thereby decreasing the sensitivity of GABA A receptors expressed on the surface of ganglion cell dendrites. Because retinal directional sensitivity is linked to GABAergic transmission, HOKS-induced expression of ACBP could provide a molecular basis for adaptation to HOKS and for the genesis of OKAN-II.

Interaction of estrogen receptor‐α ligand binding domain with nuclear proteins of aging mouse brain

“…After centrifugation, the supernatant containing the precleared nuclear extract was incubated with beads bound to mERa-LBD in the presence and absence of 1 lM 17b-estradiol. Then, the interacting proteins pulled down by mERa-LBD were separated from the beads by elution with 100 ll of high-imidazole-containing buffer (250 mM imidazole, 0.3 M NaCl, 50 mM Na 2 PO 4 , pH 8.0) and analyzed by SDS-PAGE, silver staining, and immunoblotting (Barmack et al, 2004). To rule out nonspecific binding, the nuclear extract was incubated separately with sepharose beads (Ni-IDA) and his-tag.…”

Climbing fiber activity reduces 14-3-3-θ regulated GABAA receptor phosphorylation in cerebellar Purkinje cells

“…We have used long-term HOKS to detect activity-dependent changes in gene transcription in floccular Purkinje cells (Barmack and Qian, 2002; Barmack et al, 2004). The transcripts of one such gene, GABARAP, implicated in trafficking of GABA A Rs through its interaction with a serine phosphorylated GABA A γ 2 subunit, were reduced by prolonged climbing fiber activity (Qian et al, 2011).…”

Acyl coenzyme A‐binding protein (ACBP) is phosphorylated and secreted by retinal Müller astrocytes following protein kinase C activation

“…1999). Intra‐cisternal injections of ACBP increases low voltage fast EEG activity (Barmack et al. 2004).…”

“…2004). In solutions prepared from brain lysates, an antibody to the GABA A α1 receptor co‐immunoprecipitated ACBP (Barmack et al. 2004).…”

“…Previously, we have shown that long‐term horizontal binocular optokinetic stimulation (HOKS) in the posterior→anterior direction increases the expression of ACBP in Müller glial cells (Barmack et al. 2004).…”