title: Cell-specific cre recombinase expression allows selective ablation of glutamate receptors from mouse horizontal cells.
abstract: In the mouse retina, horizontal cells form an electrically coupled network and provide feedback signals to photoreceptors and feedforward signals to bipolar cells. Thereby, horizontal cells contribute to gain control at the first visual synapse and to the antagonistic organization of bipolar and ganglion cell receptive fields. However, the nature of horizontal cell output remains a matter of debate, just as the exact contribution of horizontal cells to center-surround antagonism. To facilitate studying horizontal cell function, we developed a knockin mouse line which allows ablating genes exclusively in horizontal cells. This knockin line expresses a Cre recombinase under the promoter of connexin57 (Cx57), a gap junction protein only expressed in horizontal cells. Consistently, in Cx57+/Cre mice, Cre recombinase is expressed in almost all horizontal cells (>99%) and no other retinal neurons. To test Cre activity, we crossbred Cx57+/Cre mice with a mouse line in which exon 11 of the coding sequence for the ionotropic glutamate receptor subunit GluA4 was flanked by two loxP sites (GluA4fl/fl). In GluA4fl/fl:Cx57+/Cre mice, GluA4 immunoreactivity was significantly reduced (∼ 50%) in the outer retina where horizontal cells receive photoreceptor inputs, confirming the functionality of the Cre/loxP system. Whole-cell patch-clamp recordings from isolated horizontal cell somata showed a reduction of glutamate-induced inward currents by ∼ 75%, suggesting that the GluA4 subunit plays a major role in mediating photoreceptor inputs. The persistent current in GluA4-deficient cells is mostly driven by AMPA and to a very small extent by kainate receptors as revealed by application of the AMPA receptor antagonist GYKI52466 and concanavalin A, a potentiator of kainate receptor-mediated currents. In summary, the Cx57+/Cre mouse line provides a versatile tool for studying horizontal cell function. GluA4fl/fl:Cx57+/Cre mice, in which horizontal cells receive less excitatory input, can thus be used to analyze the contribution of horizontal cells to retinal processing.
authors.affiliation: Department of Neurobiology, University of Oldenburg, Oldenburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ströh
authors.affiliation: Life and Medical Sciences Institute, University of Bonn, Bonn, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Sonntag
authors.affiliation: Department of Neurobiology, University of Oldenburg, Oldenburg, Germany ; Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Janssen-Bienhold
authors.affiliation: Department of Neurobiology, University of Oldenburg, Oldenburg, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Schultz
authors.affiliation: Life and Medical Sciences Institute, University of Bonn, Bonn, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Cimiotti
authors.affiliation: Department of Neurobiology, University of Oldenburg, Oldenburg, Germany ; Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany.
authors.forename: Reto
authors.initials: R
authors.lastname: Weiler
authors.affiliation: Life and Medical Sciences Institute, University of Bonn, Bonn, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
authors.affiliation: Department of Neurobiology, University of Oldenburg, Oldenburg, Germany ; Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Dedek
mesh_terms: D000818:Animals; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D019426:Integrases / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D017470:Receptors, Glutamate / Q000096:biosynthesis / Q000235:genetics; D051248:Retinal Horizontal Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D017630:Connexins; C119811:Gja10 protein, mouse; D017470:Receptors, Glutamate; C045073:Cre recombinase; D019426:Integrases