Identification of retinal ganglion cell types and brain nuclei expressing the transcription factor Brn3c/Pou4f3 using a Cre recombinase knock‐in allele

Abstract

Members of the POU4F/Brn3 transcription factor family have an established role in the development of retinal ganglion cell (RGCs) types, the main transducers of visual information from the mammalian eye to the brain. Our previous work using sparse random recombination of a conditional knock-in reporter allele expressing alkaline phosphatase (AP) and intersectional genetics had identified three types of Brn3c positive (Brn3c +) RGCs. Here, we describe a novel Brn3c Cre mouse allele generated by serial Dre to Cre recombination and use it to explore the expression overlap of Brn3c with Brn3a and Brn3b and the dendritic arbor morphologies and visual stimulus response properties of Brn3c + RGC types. Furthermore, we explore brain nuclei that express Brn3c or receive input from Brn3c + neurons. Our analysis reveals a much larger number of Brn3c + RGCs and more diverse set of RGC types than previously reported. Most RGCs expressing Brn3c during development are still Brn3c positive in the adult, and all express Brn3a while only about half express Brn3b. Genetic Brn3c-Brn3b intersection reveals an area of increased RGC density, extending from dorsotemporal to ventrolateral across the retina and overlapping with the mouse binocular field of view. In addition, we report a Brn3c + RGC projection to the thalamic reticular nucleus, a visual nucleus that was not previously shown to receive retinal input. Furthermore, Brn3c + neurons highlight a previously unknown subdivision of the deep mesencephalic nucleus. Thus, our newly generated allele provides novel biological insights into RGC type classification, brain connectivity, and cytoarchitectonic.

Enhanced restoration of visual code after targeting on bipolar cells compared to retinal ganglion cells with optogenetic therapy

“…Another theoretical advantage of ON bipolar cell targeting is that it may provide access to all retinal output channels in a way that may be hard to achieve for RGC targeting given cell-type specificity of viral transduction efficiency 22 . The Brn3c Cre line provides an example of this challenge as it targets the subset of RGCs that are Brn3c-positive 40 , comprising 27 of the 42 RGC functional subtypes identified in 33 . Our parallel recordings of ReaChR and photoreceptor-derived responses in rd het mice provide an insight into the degree to which the incomplete coverage of RGC types contributes to the reduced visual code diversity in ReaChR Brn3c rd/rd.…”

“…We also produced a new transgenic line -ReaChR Brn3c rd. Brn3c Cre/WT mice (MGI: 7470766, kindly shared by Tudor Badea, National Eye Institute, NIH,USA 40 ) were bred with homozygous ReaChR Grm6 WT/WT Pde6b rd1/rd1 from the ReaChR Grm6 rd colony maintained at the University of Manchester. Mice were bred to be homozygous for ReaChR, heterozygous for Brn3c Cre and either heterozygous (ReaChR Brn3c rd het) or homozygous (ReaChR Brn3c rd/rd) for Pde6b rd1 .…”

The RBPMSCreERT2-tdTomato mouse line for studying retinal and vascular relevant diseases

“… 8 To gain a better understanding of the characteristics of RGCs and the underlying pathological mechanisms, researchers have developed various RGC-reporter knockin (KI) mice models, such as Thy1 mice 9 , 10 and Brn3/Pou4F mice. 11 , 12 , 13 , 14 Thy1 is a cell surface glycoprotein that was first discovered in mature T lymphocytes in mice. 15 It has also been found to be expressed in the central nervous system 16 and RGCs.…”

Inducible Rbpms-CreERT2 Mouse Line for Studying Gene Function in Retinal Ganglion Cell Physiology and Disease

“…Currently, a few methods have been used for gene manipulation in RGCs, including viral infection [9,[31][32][33] and gene-specific promotor-driven Cre mouse lines [34][35][36]. However, these existing tools have limitations, such as that transduction of viral vectors is limited by the delivery efficiency and toxicity and that the available Cre lines display limited Cre recombinase activities in selective RGCs but not in the entire population of RGCs [37][38][39][40][41], or they express Cre in other retinal cell types besides RGCs [42,43] or are not inducible for gene manipulation at a given time point [42,44]. Hence, there is a critical need for efficient inducible Cre mouse lines that can achieve highly effective recombination of floxed alleles specifically in RGCs in a temporally controlled manner.…”