The miR-290 and miR-302 clusters are essential for reprogramming of fibroblasts to induced pluripotent stem cells.

Unlabelled: The miR-290 and miR-302 clusters of microRNAs are highly expressed in naïve and primed pluripotent stem cells, respectively. Ectopic expression of the embryonic stem cell-specific cell cycle regulating (ESCC) family of microRNAs arising from these two clusters dramatically enhances the reprogramming of both mouse and human somatic cells to induced pluripotency. Here, we used genetic knockouts to dissect the requirement for the miR-290 and miR-302 clusters during the reprogramming of mouse fibroblasts into induced pluripotent stem cells (iPSCs) with retrovirally introduced Oct4, Sox2, and Klf4.

MLL3/MLL4 enzymatic activity shapes DNA replication timing.

Mammalian genomes are replicated in a precise order during S phase, which is cell-type-specific and correlates with local transcriptional activity, chromatin modifications and chromatin architecture. However, the causal relationships between these features and the key regulators of DNA replication timing (RT) are largely unknown. Here, machine learning was applied to quantify chromatin features, including epigenetic marks, histone variants and chromatin architectural factors, best predicting local RT under steady-state and RT changes during early embryonic stem (ES) cell differentiation.

Transcriptional repression upon S phase entry protects genome integrity in pluripotent cells.

Coincident transcription and DNA replication causes replication stress and genome instability. Rapidly dividing mouse pluripotent stem cells are highly transcriptionally active and experience elevated replication stress, yet paradoxically maintain genome integrity. Here, we study FOXD3, a transcriptional repressor enriched in pluripotent stem cells, and show that its repression of transcription upon S phase entry is critical to minimizing replication stress and preserving genome integrity.

Loss of MLL3/4 decouples enhancer H3K4 monomethylation, H3K27 acetylation, and gene activation during embryonic stem cell differentiation.

Background: Enhancers are essential in defining cell fates through the control of cell-type-specific gene expression. Enhancer activation is a multi-step process involving chromatin remodelers and histone modifiers including the monomethylation of H3K4 (H3K4me1) by MLL3 (KMT2C) and MLL4 (KMT2D). MLL3/4 are thought to be critical for enhancer activation and cognate gene expression including through the recruitment of acetyltransferases for H3K27.

G1/S restriction point coordinates phasic gene expression and cell differentiation.

Pluripotent embryonic stem cells have a unique cell cycle structure with a suppressed G1/S restriction point and little differential expression across the cell cycle phases. Here, we evaluate the link between G1/S restriction point activation, phasic gene expression, and cellular differentiation. Expression analysis reveals a gain in phasic gene expression across lineages between embryonic days E7.

Local injections of β-NGF accelerates endochondral fracture repair by promoting cartilage to bone conversion.

There are currently no pharmacological approaches in fracture healing designed to therapeutically stimulate endochondral ossification. In this study, we test nerve growth factor (NGF) as an understudied therapeutic for fracture repair. We first characterized endogenous expression of Ngf and its receptor tropomyosin receptor kinase A (TrkA) during tibial fracture repair, finding that they peak during the cartilaginous phase.

A Drosophila Tumor Suppressor Gene Prevents Tonic TNF Signaling through Receptor N-Glycosylation.

Drosophila tumor suppressor genes have revealed molecular pathways that control tissue growth, but mechanisms that regulate mitogenic signaling are far from understood. Here we report that the Drosophila TSG tumorous imaginal discs (tid), whose phenotypes were previously attributed to mutations in a DnaJ-like chaperone, are in fact driven by the loss of the N-linked glycosylation pathway component ALG3. tid/alg3 imaginal discs display tissue growth and architecture defects that share characteristics of both neoplastic and hyperplastic mutants.

The transcriptional response to tumorigenic polarity loss in Drosophila.

Loss of polarity correlates with progression of epithelial cancers, but how plasma membrane misorganization drives oncogenic transcriptional events remains unclear. The polarity regulators of the Drosophila Scribble (Scrib) module are potent tumor suppressors and provide a model for mechanistic investigation. RNA profiling of Scrib mutant tumors reveals multiple signatures of neoplasia, including altered metabolism and dedifferentiation.

Endoplasmic Reticulum Stress Activation during Total Knee Arthroplasty.

Total knee arthroplasty (TKA) is the most common remediation for knee pain from osteoarthritis (OA) and is performed 650,000 annually in the U.S. A tourniquet is commonly used during TKA which causes ischemia and reperfusion (I/R) to the lower limb but the effects of I/R on muscle are not fully understood.