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Luciano Custo Greig, Mollie Woodworth, Jeffrey L Goldberg, Sui Wang; Transcription factor Myt1L promotes neuronal fate acquisition in the developing retina. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4280.
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© ARVO (1962-2015); The Authors (2016-present)
Myt1L is a zinc finger transcription factor expressed by a variety of neuron types. In the cerebral cortex, Myt1L counteracts Notch signaling to promote differentiation of neural progenitors and repress non-neuronal fates. Interestingly, it is one of three transcription factors, in combination with Brn2 and Ascl1, capable of inducing reprogramming of fibroblasts into functional neurons. Here we investigate possible functions of Myt1L in retinal development, which have not been previously reported.
Tissue was collected from CD1 mice at the indicated developmental time points, and retinas were stained with a MYT1L guinea pig polyclonal antibody (Guoqiang Gu, Vanderbilt University). GFAP-Cre and R26 reporter mice were obtained from JAX. The indicated plasmids were injected subretinally into CD1 mouse pups at P1, electroporated with 5x80V pulses, and retinas were collected for analysis at P21. Imaging was performed on a Zeiss LSM700 confocal microscope.
We find that MYT1L is absent from progenitors, but is present in postmitotic neurons starting as early as E15.5, and well into adulthood (Figure 1A-F). It is most highly expressed by retinal ganglion cells, but is also detected at lower levels in amacrine and bipolar cells, based on co-localization with BRN3A, PAX6 and CHX10 (data not shown). In contrast, Müller glial cells do not express Myt1L, as demonstrated by lack of overlap with GFAP-Cre;R26-tdTom (Figure 1G-K). Interestingly, overexpression of Myt1L in postnatal retinal progenitors was sufficient to strongly repress generation of Müller glia. In control experiments, 56.5% ± 8.4% of electroporated cells in the INL were SOX9-positive Müller glia (Figure 1L-O), compared to only 20.9% ± 3.0% in Myt1L overexpression experiments (p <0.01).
Taken together, our results indicate that Myt1L is expressed by retinal ganglion cells, amacrine cells, and bipolar cells during development, and that it can strongly repress generation of Müller glia by postnatal retinal progenitors.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
Figure 1. Myt1L is expressed in the developing retina and promotes neuronal differentiation. Myt1L expression begins in postmitotic RGCs and continues through adulthood (A-F). Myt1L is not expressed by Müller glia marked by GFAP-Cre;Rosa26-Tom (G-K’). Electroporation at P1 labels Müller glia, rods, and bipolar cells (L). Electroporation of CAG-Myt1L results in fewer Müller glia than CAG-tdTom alone (M-O).
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