Mller glia, which closely resemble retinal progenitor cells (RPCs) in their morphology and gene expression profile, are the last cell type generated in the developing retina. Mammalian Mller glia, however, rapidly lose the ability to proliferate and generate neurons following specification. The molecular mechanisms that allow RPCs to become gliogenic, and lead Mller glia to lose neurogenic competence remain poorly understood. We have recently identified the LIM homeodomain factor Lhx2 as a central regulator of MG differentiation and function, and now seek to characterize its mechanism of action. Based on our preliminary findings, we hypothesize that Lhx2 cooperates with NFI and SoxE factors to initiate gliogenesis. We propose that NFI and SoxE factors bind to target sequences that control expression of gliogenic and glial-specific genes in late-stage RPCs, which then exposes binding site for Lhx2. Lhx2 then induces chromatin opening at these sites, which in turn leads to stable activation of these genes. In postmitotic glial precursors, in contrast, rising levels of Rnf12 inhibit Ldb1/Lhx2-dependent transcriptional activation of neurogenic bHLH genes, eventually leading to a permanent loss of neurogenic competence in mature Mller glia.
We aim to determine how NFI, SoxE, and Lhx2 act to drive glial differentiation and restrict neurogenic competence. We will first determine whether NFI factors promote gliogenic competence and glial differentiation in retina. We will next test whether NFI and SoxE directly regulate expression of gliogenic and glial-specific genes, and determine whether selective loss of Lhx2 in differentiating glia reduces chromatin accessibility at cis-regulatory elements that control glial-specific genes. We will also test whether NFI and SoxE direct target site selection by Lhx2 in late- stage RPCs and glial precursors. In addition to these studies of how glial differentiation is controlled, we intend to determine how Lhx2-dependent neurogenic competence is lost in differentiating Mller glia. We will determine whether Rnf12 acts in an Lhx2-dependent manner to drive loss of neurogenic competence in differentiating and mature Mller glia. Finally, we will identify molecules that mediate Lhx2-dependent transcriptional repression in postnatal retina. We anticipate that a full understanding of the mechanism by which Lhx2 regulates gliogenesis will identify key targets for drug and gene-based therapies aimed at restoring vision through controlled dedifferentiation of Mller glia.

Public Health Relevance

Retinal Mller glia are a potential source for regeneration of photoreceptors lost in disease, but in most species, lose the ability to give rise to neurons as they differentiate. We have identified several genes that may be central regulators of both glial differentiation and loss of neurogenic competence in Mller glia, and propose to investigate their function. Identifying genes that control neurogenic competence in glia may result in the development of novel therapies to restore vision to the visually impaired and blind.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Greenwell, Thomas
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Johns Hopkins University
Schools of Medicine
United States
Zip Code
de Melo, Jimmy; Blackshaw, Seth (2018) In Vivo Electroporation of Developing Mouse Retina. Methods Mol Biol 1715:101-111
de Melo, Jimmy; Clark, Brian S; Venkataraman, Anand et al. (2018) Ldb1- and Rnf12-dependent regulation of Lhx2 controls the relative balance between neurogenesis and gliogenesis in the retina. Development 145:
Liu, Sheng; Zibetti, Cristina; Wan, Jun et al. (2017) Assessing the model transferability for prediction of transcription factor binding sites based on chromatin accessibility. BMC Bioinformatics 18:355
Remez, Liv Aleen; Onishi, Akishi; Menuchin-Lasowski, Yotam et al. (2017) Pax6 is essential for the generation of late-born retinal neurons and for inhibition of photoreceptor-fate during late stages of retinogenesis. Dev Biol 432:140-150
Clark, Brian S; Blackshaw, Seth (2017) Understanding the Role of lncRNAs in Nervous System Development. Adv Exp Med Biol 1008:253-282
Gueta, Keren; David, Ahuvit; Cohen, Tsadok et al. (2016) The stage-dependent roles of Ldb1 and functional redundancy with Ldb2 in mammalian retinogenesis. Development 143:4182-4192
de Melo, Jimmy; Clark, Brian S; Blackshaw, Seth (2016) Multiple intrinsic factors act in concert with Lhx2 to direct retinal gliogenesis. Sci Rep 6:32757
Thein, Thuzar; de Melo, Jimmy; Zibetti, Cristina et al. (2016) Control of lens development by Lhx2-regulated neuroretinal FGFs. Development 143:3994-4002
de Melo, Jimmy; Zibetti, Cristina; Clark, Brian S et al. (2016) Lhx2 Is an Essential Factor for Retinal Gliogenesis and Notch Signaling. J Neurosci 36:2391-405
Mattar, Pierre; Ericson, Johan; Blackshaw, Seth et al. (2015) A conserved regulatory logic controls temporal identity in mouse neural progenitors. Neuron 85:497-504

Showing the most recent 10 out of 16 publications