Identification and Characterization of FGF2-Dependent mRNA: microRNA Networks During Lens Fiber Cell Differentiation

Abstract

MicroRNAs (miRNAs) and fibroblast growth factor (FGF) signaling regulate a wide range of cellular functions, including cell specification, proliferation, migration, differentiation, and survival. In lens, both these systems control lens fiber cell differentiation; however, a possible link between these processes remains to be examined. Herein, the functional requirement for miRNAs in differentiating lens fiber cells was demonstrated via conditional inactivation of Dicer1 in mouse (Mus musculus) lens. To dissect the miRNA-dependent pathways during lens differentiation, we used a rat (Rattus norvegicus) lens epithelial explant system, induced by FGF2 to differentiate, followed by mRNA and miRNA expression profiling. Transcriptome and miRNome analysis identified extensive FGF2-regulated cellular responses that were both independent and dependent on miRNAs. We identified 131 FGF2-regulated miRNAs. Seventy-six of these miRNAs had at least two in silico predicted and inversely regulated target mRNAs. Genes modulated by the greatest number of FGF-regulated miRNAs include DNA-binding transcription factors Nfib, Nfat5/OREBP, c-Maf, Ets1, and N-Myc. Activated FGF signaling influenced bone morphogenetic factor/transforming growth factor-β, Notch, and Wnt signaling cascades implicated earlier in lens differentiation. Specific miRNA:mRNA interaction networks were predicted for c-Maf, N-Myc, and Nfib (DNA-binding transcription factors); Cnot6, Cpsf6, Dicer1, and Tnrc6b (RNA to miRNA processing); and Ash1l, Med1/PBP, and Kdm5b/Jarid1b/Plu1 (chromatin remodeling). Three miRNAs, including miR-143, miR-155, and miR-301a, down-regulated expression of c-Maf in the 3′-UTR luciferase reporter assays. These present studies demonstrate for the first time global impact of activated FGF signaling in lens cell culture system and predicted novel gene regulatory networks connected by multiple miRNAs that regulate lens differentiation.

Roles of FGF-2 and TGF-beta/FGF-2 on differentiation of human mesenchymal stem cells towards nucleus pulposus-like phenotype

“…However, FGF-2 down-regulates the ERK signaling pathway which is not in agreement with the previous studies. FGF-2 can promote differentiation of MSCs with the activation of Notch signaling pathway, which will also influence the TGF-beta signaling pathway (Liu et al, 2013;Wolf et al, 2013). Our results suggested high proliferation and influenced p-Smad3 expression; based on previous studies, we speculated that Notch signaling pathway might be activated which led to increased proliferation.…”

Differentiation State-Specific Mitochondrial Dynamic Regulatory Networks Are Revealed by Global Transcriptional Analysis of the Developing Chicken Lens

“…Combining these data with regulatory RNA analysis during lens cell differentiation (Wolf et al 2013) could pinpoint novel regulators of transcriptional content and the transcriptional program that occurs during the differentiation of lens cells. Further analysis of the data will provide a greater understanding of a wide range of other important processes in the lens, including lens cell survival, homeostasis, differentiation, and degradation of other lens organelles for lens cell differentiation including the nucleus, endoplasmic reticulum and Golgi apparatus, all of which are also degraded during formation of the organelle free zone.…”

Systems biology of lens development: A paradigm for disease gene discovery in the eye

“…Investigation of ncRNAs in lens biology has been initiated (Frederikse et al, 2006; Li and Piatigorsky, 2009; Shaham et al, 2013; Wolf et al, 2013a; Xu, 2009). miRNAs are a subset of ncRNAs involved in post-transcriptional regulation by direct binding of target mRNAs to initiate their decay or inhibit translation (Brosnan and Voinnet, 2009; Morris et al, 2010).…”

“…miRNAs are a subset of ncRNAs involved in post-transcriptional regulation by direct binding of target mRNAs to initiate their decay or inhibit translation (Brosnan and Voinnet, 2009; Morris et al, 2010). Lens- and cornea-specific Dicer1 null mice exhibit severe lens and corneal defects, indicating the requirement of miRNAs in their development (Li and Piatigorsky, 2009; Wolf et al, 2013a). …”