Nuclear pore complexes (NPCs) influence gene expression besides their established function in nuclear transport. The TREX-2 complex localizes to the NPC basket and affects gene-NPC interactions, transcription and mRNA export. How TREX-2 regulates the gene expression machinery is unknown. Here, we show that TREX-2 interacts with the Mediator complex, an essential regulator of RNA Polymerase (Pol) II. Structural and biochemical studies identify a conserved region on TREX-2, which directly binds the Mediator Med31/Med7N submodule. TREX-2 regulates assembly of Mediator with its Cdk8 kinase and is required for recruitment and site-specific phosphorylation of Pol II. Transcriptome and phenotypic profiling confirm that TREX-2 and Med31 are functionally interdependent. TREX-2 additionally uses its Mediator-interacting surface to regulate mRNA export suggesting a mechanism for coupling transcription initiation and early steps of mRNA processing at the Mediator level. In sum, we provide insight into how NPC-associated adaptor complexes can access the core transcription machinery. Overall design: RNAseq was performed from WT, sac3?, cdk8? and Sac3 R288D mutant cells. For each strain triplicates were analyzed. WT strain was sac3? transformed with pRS315 SAC3 WT
The Nuclear Pore-Associated TREX-2 Complex Employs Mediator to Regulate Gene Expression.
Subject
View SamplesThe differentiated state of somatic cells provides barriers for the efficient derivation of induced pluripotent stem cells (iPSCs). To address why some cell types reprogram more readily than others, we studied the effect of combined modulation of cellular signaling pathways. This revealed that inhibition of TGF together with activation of Wnt signaling in presence of ascorbic acid allows >80% of murine fibroblasts to acquire pluripotency after one week of reprogramming factor expression. In contrast, hepatic progenitors and blood progenitors predominantly required only TGF inhibition or canonical Wnt activation, respectively, to reprogram at efficiencies approaching 100%. Strikingly, blood progenitors reactivated endogenous pluripotency loci in a highly synchronous manner. We further demonstrate that expression of specific chromatin-modifying enzymes and reduced TGF/MAP kinase activity are intrinsic properties associated with the unique reprogramming response of these cells. Together, our observations define novel cell type-specific requirements for the rapid and synchronous reprogramming of somatic cells.
Combinatorial modulation of signaling pathways reveals cell-type-specific requirements for highly efficient and synchronous iPSC reprogramming.
Specimen part, Time
View SamplesPrimary murine osteoblasts were isolated form the calvariae of newborn mice. 10 days after the addition of ascorbic acid (50 g/ml) and -glycerophosphate (10 mM), cells were serum-starved over night and then incubated for 6 hours with condtioned medium of MDA-PCa2b cells or conditioned medium of PC-3 cells
Osteolytic prostate cancer cells induce the expression of specific cytokines in bone-forming osteoblasts through a Stat3/5-dependent mechanism.
Specimen part
View SamplesGenome-wide comparative gene expression analysis of callus tissue of osteoporotic mice (Col1a1-Krm2 and Lrp5-/-) and wild-type were performed to identify candidate genes that might be responsible for the impaired fracture healing observed in Col1a1-Krm2 and Lrp5-/- mice.
Osteoblast-specific Krm2 overexpression and Lrp5 deficiency have different effects on fracture healing in mice.
Sex, Age, Specimen part
View SamplesDLK1/FA-1 (delta-like 1/fetal antigen-1) is a transmembrane protein belonging to Notch/Delta family that acts as a membrane-associated or a soluble protein to regulate regeneration of a number of adult tissues. Here, we examined the role of DLK1/FA-1 in bone biology using osteoblast-specific-Dlk1 over-expressing mice (Col1-Dlk1). Col1-Dlk1 mice displayed growth retardation and significantly reduced total body weight and bone mineral density (BMD). CT-scanning revealed a reduced trabecular and cortical bone volume fraction. Tissue-level histomorphometric analysis demonstrated decreased bone formation rate and enhanced bone resorption in Col1-Dlk1 as compared to WT. At a cellular level, DLK1 markedly reduced the total number of bone marrow (BM)-derived CFU-F, as well as their osteogenic capacity. In a number of in vitro culture systems, DLK1 stimulated osteoclastogenesis indirectly through osteoblast-dependent increased production of pro-inflammatory bone resorbing cytokines (e.g, Il7, Tnfa and Ccl3). We found that ovariectomy (ovx)-induced bone loss was associated with increased production of DLK1 in bone marrow by activated T-cells. However, Dlk1-/- mice were protected from ovx-induced bone loss. Thus, we identified DLK1 as a novel regulator of bone mass that function to inhibit bone formation and to stimulate bone resorption. Increasing DLK1 production by T-cells under estrogen deficiency suggests its possible use as a therapeutic target for preventing postmenopausal bone loss.
DLK1 is a novel regulator of bone mass that mediates estrogen deficiency-induced bone loss in mice.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors.
Sex, Age, Specimen part, Disease
View SamplesIn the present study we analyzed the effect of primary osteoporosis and advanced donor age on the transcriptome of human mesenchymal stem cells (hMSC; alternatively named mesenchymal stromal cells) from bone marrow. Human MSC of elderly patients suffering from osteoporosis were isolated from femoral heads after low-energy fracture of the femoral neck. Control cells were obtained from bone marrow of femoral heads of middle-aged, non-osteoporotic donors after total hip arthroplasty.
The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors.
Sex, Age, Specimen part, Disease
View SamplesIn the present study we analyzed the effect of cellular senescence on the transcriptome of human mesenchymal stem cells (hMSC; alternatively named mesenchymal stromal cells) from bone marrow. Human MSC were isolated from femoral heads of non-osteoporotic donors after total hip arthroplasty.
The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors.
Sex, Age, Specimen part
View SamplesIn the present study we analyzed the effect of primary osteoporosis on the transcriptome of human mesenchymal stem cells (hMSC; alternatively named mesenchymal stromal cells) from human bone marrow. Human MSC of elderly patients suffering from osteoporosis were isolated from femoral heads after low-energy fracture of the femoral neck. Bone marrow of age-matched, non-osteoporotic donors was obtained of femoral heads after total hip arthroplasty.
The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors.
Sex, Age, Specimen part, Disease
View SamplesIn the present study we analyzed the effect of advanced donor age on the transcriptome of human mesenchymal stem cells (hMSC; alternatively named mesenchymal stromal cells) from bone marrow. Human MSC of elderly and middle-aged patients without symptoms of osteoporosis were isolated from femoral heads after total hip arthroplasty.
The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors.
Sex, Age, Specimen part
View Samples