Project description:While the regulatory landscape during stem cell differentiation has been well characterized, the shared and unique regulatory mechanisms in different ectodermally-derived epithelial cells have not been well described. Through defining the complement of super enhancers and typical enhancers in corneal epithelium for the first time, we show that regulatory regions are often shared between cell types of the same lineage, and that corneal super enhancers are already marked as potential regulatory domains in embryonic stem cells. Through the enrichment of KLF motifs in enhancers, we identified and defined a novel role for Kruppel family member KLF7 in promoting the corneal progenitor cell state, in many cases working antagonistically to corneal differentiation promoting KLF4. Our work highlights the importance of balance between proliferation and differentiation, both for proper tissue development and for homeostasis.
Project description:While the regulatory landscape during stem cell differentiation has been well characterized, the shared and unique regulatory mechanisms in different ectodermally-derived epithelial cells have not been well described. Through defining the complement of super enhancers and typical enhancers in corneal epithelium for the first time, we show that regulatory regions are often shared between cell types of the same lineage, and that corneal super enhancers are already marked as potential regulatory domains in embryonic stem cells. Through the enrichment of KLF motifs in enhancers, we identified and defined a novel role for Kruppel family member KLF7 in promoting the corneal progenitor cell state, in many cases working antagonistically to corneal differentiation promoting KLF4. Our work highlights the importance of balance between proliferation and differentiation, both for proper tissue development and for homeostasis.
Project description:While the regulatory landscape during stem cell differentiation has been well characterized, the shared and unique regulatory mechanisms in different ectodermally-derived epithelial cells have not been well described. Through defining the complement of super enhancers and typical enhancers in corneal epithelium for the first time, we show that regulatory regions are often shared between cell types of the same lineage, and that corneal super enhancers are already marked as potential regulatory domains in embryonic stem cells. Through the enrichment of KLF motifs in enhancers, we identified and defined a novel role for Kruppel family member KLF7 in promoting the corneal progenitor cell state, in many cases working antagonistically to corneal differentiation promoting KLF4. Our work highlights the importance of balance between proliferation and differentiation, both for proper tissue development and for homeostasis.
Project description:Neurons in the central nervous system (CNS) lose their ability to regenerate early in development, but the underlying mechanisms are unknown. By screening genes developmentally regulated in retinal ganglion cells (RGCs), we identified Krüppel-like factor-4 (KLF4) as a transcriptional repressor of axon growth in RGCs and other CNS neurons. RGCs lacking KLF4 showed increased axon growth both in vitro and after optic nerve injury in vivo. Related KLF family members suppressed or enhanced axon growth to differing extents, and several growth-suppressive KLFs were up-regulated postnatally, whereas growth-enhancing KLFs were down-regulated. Thus, coordinated activities of different KLFs regulate the regenerative capacity of CNS neurons.
Project description:miRNAs are endogenously expressed 18- to 25-nucleotide RNAs that regulate gene expression through translational repression by binding to a target mRNA. Recently, it has been indicated that miRNAs are closely related to osteogenesis. Our previous data suggested that miR-30 family members might be important regulators during the biomineralization process. However, whether and how they modulate osteogenic differentiation have not been explored. In this study, we demonstrated that miR-30 family members negatively regulate BMP-2-induced osteoblast differentiation by targeting Smad1 and Runx2. Evidentially, overexpression of miR-30 family members led to a decrease of alkaline phosphatase activity, whereas knockdown of them increased the activity. Then bioinformatic analysis identified potential target sites of the miR-30 family located in the 3' untranslated regions of Smad1 and Runx2. Western blot analysis and quantitative RT-PCR assays demonstrated that miR-30 family members inhibit Smad1 gene expression on the basis of repressing its translation. Furthermore, dual-luciferase reporter assays confirmed that Smad1 is a direct target of miR-30 family members. Rescue experiments that overexpress Smad1 and Runx2 significantly eliminated the inhibitory effect of miR-30 on osteogenic differentiation and provided strong evidence that miR-30 mediates the inhibition of osteogenesis by targeting Smad1 and Runx2. Also, the inhibitory effects of the miR-30 family were validated in mouse bone marrow mesenchymal stem cells. Therefore, our study uncovered that miR-30 family members are key negative regulators of BMP-2-mediated osteogenic differentiation.