Ectopic insert-dependent neuronal expression of GFAP promoter-driven AAV constructs in adult mouse retina

• Published in: Frontiers in cell and developmental biology 2022-09, Vol.10, p.914386
• Main Authors: Le, Nguyet, Appel, Haley, Pannullo, Nicole, Hoang, Thanh, Blackshaw, Seth
• Format: Article
• Language: English
• Subjects: adeno associated viral vectors; adeno-associated virus; Cell and Developmental Biology; glia; glial fibrillary acidic protein; muller glia; reprogramming
• ISSN: 2296-634X; 2296-634X
• DOI: 10.3389/fcell.2022.914386

Direct reprogramming of retinal Müller glia is a promising avenue for replacing photoreceptors and retinal ganglion cells lost to retinal dystrophies. However, questions have recently been raised about the accuracy of studies claiming efficient glia-to-neuron reprogramming in retina that were conducted using GFAP mini promoter-driven adeno-associated virus (AAV) vectors. In this study, we have addressed these questions using GFAP mini promoter-driven AAV constructs to simultaneously overexpress the mCherry reporter and candidate transcription factors predicted to induce glia-to-neuron conversion, in combination with prospective genetic labeling of retinal Müller glia using inducible Cre-dependent GFP reporters. We find that, while control GFAP-mCherry constructs express faithfully in Müller glia, 5 out of 7 transcription factor overexpression constructs tested are predominantly expressed in amacrine and retinal ganglion cells. These findings demonstrate strong insert-dependent effects on AAV-based GFAP mini promoter specificity that preclude its use in inferring cell lineage relationships when studying glia-to-neuron conversion in retina.