Project description:Rodent lipid metabolism and postnatal nutrition is fundamentally different from humans. Therefore, we used embryonic stem cells (hESC) to model hepatic development in human. Pluripotent stem cells reliably produce hepatocytes with neonatal characteristics5. Postpartum was mimicked by the removal of oncostatin M (OSM), lost due to the migration of hematopoietic cells to the bone marrow after birth, and the concomitant addition of oleic acid (OA) and linoleic acid (LA), major components of breast milk.
Project description:Mammalian cardiomyocytes rapidly mature after birth, with hallmarks such as cell-cycle exit, binucleation, and metabolic switch to oxidative phosphorylation of lipids. The causes and transcriptional programs regulating cardiomyocyte maturation are not fully understood yet. Thus, we performed single cell RNA-seq of neonatal and postnatal day 7 rat hearts to identify the key factors for this process and found AP-1 as a key factor to regulate cardiomyocyte maturation. To find the mechanism of AP-1 during cardiomyocyte maturation, we performed RNA-seq analysis of neonatal rat ventricular cardiomyocytes and found Ap-1 promote cardiomyocyte maturation by regulating cardiomyocyte metabolism.
Project description:Alternative splicing greatly expands the proteomic diversity but its functional impact is often unclear. Here, we identify a highly conserved and temporally coordinated cell-type-specific splicing program, which is activated in part by ESRP2 during postnatal liver development. Consistent with failure of many neonatal-to-adult splicing transitions, Esrp2 null mice exhibit persistent expression of fetal markers and loss of mature hepatocyte characteristics. Conversely, ectopic expression of ESRP2 in immature mouse or human hepatocytes results in a reciprocal switch in splicing. Our findings define an essential role for ESRP2 in generation of conserved repertoires of adult splice isoforms that facilitate postnatal liver maturation. Mouse liver RNA was isolated with Trizol (Invitrogen). Hi-Seq libraries were prepared and paired-end 100bp Illumina sequencing was performed on mouse liver samples from different developmental stages.
Project description:Astrocytes are intimately linked with brain vessels, a relationship that is critical for neuronal health and function. However, key astroglial molecular factors that drive these physical and functional associations during postnatal brain development have not yet been identified. We characterized structural and transcriptional changes in mouse cortical astrocytes and microvessels during the first two postnatal weeks and found that high-mobility group box 1 (Hmgb1), normally upregulated with injury and involved in adult cerebrovascular repair, was highly expressed in astrocytes at birth to then decreased rapidly. Astrocyte-selective ablation of Hmgb1 in newborn mice affected astrocyte morphology and endfoot placement, induced disruption of endfoot proteins connexin43 and aquaporin-4, induced transcriptional changes in astrocytes, and profoundly altered endothelial cell ultrastructure. While lack of astroglial Hmgb1 did not affect the blood-brain barrier or angiogenesis postnatally, it impaired neurovascular coupling and behavior in adult mice. These findings identify astroglial Hmgb1 as a key player in postnatal gliovascular maturation.
Project description:Alternative splicing greatly expands the proteomic diversity but its functional impact is often unclear. Here, we identify a highly conserved and temporally coordinated cell-type-specific splicing program, which is activated in part by ESRP2 during postnatal liver development. Consistent with failure of many neonatal-to-adult splicing transitions, Esrp2 null mice exhibit persistent expression of fetal markers and loss of mature hepatocyte characteristics. Conversely, ectopic expression of ESRP2 in immature mouse or human hepatocytes results in a reciprocal switch in splicing. Our findings define an essential role for ESRP2 in generation of conserved repertoires of adult splice isoforms that facilitate postnatal liver maturation.
Project description:Tissue stem cells preserve a certain level of potency to maintain intact tissue integrity after various injury. Postnatal dermal fibroblasts lose differentiation potential for regenerative healing that recreates normal tissue including functional hair follicles (HFs), however, their intrinsic cellular changes are not understood yet. Here, we uncover a postnatal maturation process in papillary fibroblasts (PFs) mediated by Twist2-driven chromatin and transcriptional remodeling. Within 4 days after birth, dermal PFs lost WNT transcription factors (TFs) and target gene expressions accompanied by loss of H3K27ac expression. Through single-cell transcriptomics, ATAC-seq and ChIP-seq profiling, we define a postnatal maturation trajectory of PFs, in addition to loss of regenerative trajectory, triggered by decrease of H3K27ac and chromatic accessibility. In vivo inhibition of histone deacetylation delays the postnatal chromatin remodeling and maintains developmental signaling and differentiation potential in PFs. TF motif analysis on the chromatin regions losing accessibility identifies TWIST as a potential regulator specifying these regions. Using Twist2 conditional knock-out mouse model, we unearth a postnatal role of Twist2 TF as governing the postnatal maturation process resulting in switch-off of developmental pathways after birth. Together, our findings expose a comprehensive intracellular mechanism driving postnatal maturation in dermal fibroblasts with profound implications for regenerative medicine.