Friday, May 9, 2025
5/9/2025
Transcriptional control of gene expression in the lens - Lens developmental defects result in cataract. Thus, it is critical to define the proteins and the mechanisms that mediate regulatory control in lens development. Toward this goal, we developed a bioinformatics resource iSyTE (integrated Systems Tool for Eye gene discovery) and predicted that the small Maf transcription factors (TFs) Mafg and Mafk are significantly expressed in the lens and are necessary for its development and transparency. Because Mafg and Mafk can bind the cis-regulatory sites bound by the human cataract-linked gene c-Maf, and because their binding is influenced by other co-regulator partners like Nrf2, the investigation of these unexamined small Mafs in the lens is critical for understanding the role of Maf-family TFs in cataract. In support of iSyTE’s prediction, we find Mafg-/-:Mafk-/- double knockout (Mafg/kDKO) mice show embryonic-onset lens developmental defects, exhibiting abnormalities in lens epithelium and fiber cells. Moreover, our data shows that when one of the wild-type Mafk alleles is retained in a homozygous Mafg KO background, as in Mafg-/-:Mafk+/- compound KO (Mafg/kCPKO), this rescues the embryonic lens defects but results in adult cataract. We also find mice null for the small Maf coregulator TF, Nrf2, exhibit cataract. These data indicate a role for Mafg, Mafk and Nrf2 in lens transcriptional control. In support of this, bulk RNA-seq on Mafg/kDKO lenses identifies a cohort of differentially expressed transcripts, among which are genes relevant to lens cell biology, and whose deficiency causes human cataract, as well as novel candidates that can advance our knowledge on the mechanisms in lens development. Further, microarray profiling of Mafg/kCPKO lenses prior to cataract also identifies misexpression of genes relevant to lens biology. Thus, Mafg/kDKO and Mafg/kCPKO mice, along with Nrf2cKO, present novel models to examine small Maf-based control mechanisms in the lens and their impact on c-Maf’s function. Thus, this proposal addresses the hypothesis that Mafg, Mafk and their co-regulators mediate key lens transcriptional control that also impacts c-Maf function in the lens. This will be tested as follows. (Aim 1) Characterize Mafg/kDKO, Mafg/kCPKO and Nrf2cKO mice to define the etiology of the lens cellular defects and cataract. (Aim 2) Gain insights into the molecular underpinnings of the lens defects by performing multiomics single nuclei (sn)RNA-seq to identify cell-specific transcriptome alterations in Mafg/kDKO, Mafg/kCPKO, c-MafKO and Nrf2cKO lenses. Additionally, perform snATAC- seq to identify lens cell-specific chromatin accessibility changes. (Aim 3) Elucidate the direct genomic targets of for Mafg, Mafk, c-Maf and Nrf2 in the lens by chromatin immunoprecipitation followed by sequencing (ChIP-seq) on wild-type mouse lenses. Further, investigate high-priority Mafg and Mafk lens targets by reporter assays. Finally, analyze these Mafg, Mafk, c-Maf and Nrf2 regulatory data within the larger context of the existing lens regulatory data to derive Maf downstream gene regulatory networks (GRNs) in the lens. The impact of this innovative proposal is: it will characterize small Maf-transcriptional control in the lens, uncover its functional connectivity with Nrf2 and the human cataract-linked TF, c-Maf, and define lens pathology at cellular resolution.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).