Hematopoietic stem cells (HSCs) are identified by their ability to sustain prolonged blood cell production in vivo, although recent evidence suggests that durable self-renewal (DSR) is shared by HSC subtypes with distinct self-perpetuating differentiation programs. Net expansions of DSR-HSCs occur in vivo, but molecularly defined conditions that support similar responses in vitro are lacking. We hypothesized that this might require a combination of factors that differentially promote HSC viability, proliferation and self-renewal. We now demonstrate that HSC survival and maintenance of DSR potential is variably supported by different Steel factor (SF)-containing cocktails with similar HSC-mitogenic activities. In addition, stromal cells produce other factors, including nerve growth factor and collagen 1, that can antagonize the apoptosis of initially quiescent adult HSCs and, in combination with SF and interleukin-11, produce >15-fold net expansions of DSR-HSCs ex vivo within 7 days. These findings suggest a new molecular basis for HSC control and expansion.
Distinct stromal cell factor combinations can separately control hematopoietic stem cell survival, proliferation, and self-renewal.
Specimen part
View SamplesMouse haematopoietic stem cells (HSCs) undergo a post-natal transition in several properties, including a marked reduction in their self-renewal activity. We now show that the developmentally timed change in this key function of HSCs is associated with their decreased expression of Lin28b and an accompanying increase in their let-7 microRNA levels. Lentivirus(LV)-mediated overexpression of Lin28 in adult HSCs elevates their self-renewal activity in transplanted irradiated hosts, as does overexpression of Hmga2, a well-established let-7 target that is upregulated in fetal HSCs. Conversely, HSCs from fetal Hmga2-/- mice do not display the heightened self-renewal activity that is characteristic of wild-type fetal HSCs. Interestingly, overexpression of Hmga2 in adult HSCs does not mimic the ability of elevated Lin28 to activate a fetal lymphoid differentiation program. Thus Lin28b may act as a master regulator of developmentally timed changes in HSC programs with Hmga2 serving as its specific downstream modulator of HSC self-renewal potential.
The Lin28b-let-7-Hmga2 axis determines the higher self-renewal potential of fetal haematopoietic stem cells.
Specimen part
View SamplesDrosophila melanogaster expresses three classes of small RNAs, which are classified according to their mechanisms of biogenesis. MicroRNAs are ~22-23-nt, ubiquitously expressed small RNAs that are sequentially processed from hairpin-like precursors by Drosha/Pasha and Dcr-1/Loquacious complexes. MicroRNAs usually associate with AGO1 and regulate the expression of protein-coding genes. Piwi-interacting RNAs (piRNAs) of ~24-28-nt associate with Piwi-family proteins and can arise from single-stranded precursors. piRNAs function in transposon silencing and are mainly restricted to gonadal tissues. Endo-siRNAs are found in both germline and somatic tissues. These ~21-nt RNAs are produced by a distinct Dicer, Dcr-2, and do not depend on Drosha/Pasha complexes. They predominantly bind to AGO2 and target both mobile elements and protein-coding genes. Surprisingly, a subset of endo-siRNAs strongly depend for their production on the dsRNA-binding protein Loquacious (Loqs), thought generally to be a partner for Dcr-1 and a co-factor for miRNA biogenesis. Endo-siRNA production depends on a specific Loqs isoform, Loqs-PD, which is distinct from the one, Loqs-PB, required for the production of microRNAs. Paralleling their roles in the biogenesis of distinct small RNA classes, Loqs-PD and Loqs-PB bind to different Dicer proteins, with Dcr-1/Loqs-PB complexes and Dcr-2/Loqs-PD complexes driving microRNA and endo-siRNA biogenesis, respectively. Small RNA profiling by high throughput sequencing Overall design: Total RNA was isolated using Trizol reagent (Invitrogen) and size-fractionated by PAGE into 19-24nt. These were independently processed and sequenced using the Illumina GAII platform. In total, six libraries were analyzed.
Processing of Drosophila endo-siRNAs depends on a specific Loquacious isoform.
Cell line, Subject
View SamplesMind-body practices that elicit the relaxation response (RR) have been used worldwide for millennia to prevent and treat disease. The RR is believed to be the counterpart to stress response and is characterized by decreased oxygen consumption, increased exhaled nitric oxide, and reduced psychological distress. Individuals experiencing chronic psychological stress have the opposite pattern of physiology and a characteristic transcriptional profile. We hypothesized that consistent, long-term practice of RR techniques results in characteristic changes in gene expression. We tested this hypothesis by assessing the transcriptional profile of whole blood in healthy, long-term practitioners of daily RR practice (group M) in comparison to healthy controls (group N1). The signature obtained has been validated on new subject data.
Genomic counter-stress changes induced by the relaxation response.
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View SamplesHyperglycemic memory is part of the pathogenesis of diabetic retinopathy. We established a novel mouse model of intermediate-term hyperglycemic memory and demonstrated that changes in gene expression and microvascular damage in the neurovascular unit of the diabetic retina persist after euglycemic reentry, indicating memory.
Hyperglycaemic memory affects the neurovascular unit of the retina in a diabetic mouse model.
Specimen part, Disease
View SamplesThe signaling pathways orchestrating both the evolution and development of language in the human brain remain unknown. To date, the transcription factor FOXP2 is the only gene implicated in Mendelian forms of human speech and language dysfunction1,2. It has been proposed, that the amino acid composition in the human variant of FOXP2 has undergone accelerated evolution, and this change occurred around the time of language emergence in humans3,4. However, this remains controversial, and whether the acquisition of these amino acids in human FOXP2 has any functional consequence in human neurons remains untested. Here, we demonstrate that these two amino acids confer new functionality in terms of differential transcriptional regulation, and extend these observations to in vivo brain, showing that several of the differential FOXP2 targets significantly overlap with genes different between human and chimpanzee brain. We also identify novel relationships among the differentially expressed genes with additional critical regulators of neuronal development. These data provide support for the functional relevance of changes that occur on the human lineage by showing that the two amino acids unique to human FOXP2 can lead to significant differences in gene expression patterns across brain evolution, with direct consequences for human brain development and disease. Since FOXP2 has an important role in the use of language in humans, the identified targets may have a critical function in the development and evolution of language circuitry in humans.
Human-specific transcriptional regulation of CNS development genes by FOXP2.
Specimen part, Cell line
View SamplesPsoriasis is a chronic inflammatory skin disease of unknown etiology. Although macrophages and dendritic cells (DCs) have been proposed to drive the psoriatic cascade, their largely overlapping phenotype hampered studying their respective role. Topical application of Imiquimod, a Toll-like receptor 7 agonist, induces psoriasis in patients and psoriasiform inflammation in mice. We showed that daily application of Imiquimod for 14 days recapitulated both the initiation and the maintenance phase of psoriasis. Based on our ability to discriminate Langerhans cells (LCs), conventional DCs, monocytes, monocyte-derived DCs and macrophages in the skin, we characterized their dynamics during both phases of psoriasis. During the initiation phase, neutrophils infiltrated the epidermis whereas monocytes and monocyte-derived DCs were predominant in the dermis. During the maintenance phase, LCs and macrophage numbers increased in the epidermis and dermis, respectively. LC expansion resulted from local proliferation, a conclusion supported by transcriptional analysis. Continuous depletion of LCs during the course of Imiquimod treatment aggravated chronic psoriatic symptoms as documented by an increased influx of neutrophils and a stronger inflammation. Therefore, by developing a mouse model that mimics the human disease more accurately, we established that LCs play a negative regulatory role during the maintenance phase of psoriasis.
Dynamics and Transcriptomics of Skin Dendritic Cells and Macrophages in an Imiquimod-Induced, Biphasic Mouse Model of Psoriasis.
Specimen part, Treatment
View SamplesA case of transcriptional gene silencing, originally observed in tetraploid Arabidopsis plants, created an epiallele resistant to many mutations or inhibitor treatments that activate other suppressed genes. This raised the question about the molecular basis of this extreme stability.
Cooperation of multiple chromatin modifications can generate unanticipated stability of epigenetic States in Arabidopsis.
Specimen part
View SamplesGene Expression in d5 wound-edge tissues of MFG-E8 WT and MFG-E8 KO mice
Correction of MFG-E8 Resolves Inflammation and Promotes Cutaneous Wound Healing in Diabetes.
Specimen part
View SamplesComprehensive RNA-seq experiments in control and PRMT5 and WDR77 shRNA infected cells delineate the role of PRMT5/WDR77 complex in promoting breast cancer oncogenesis Overall design: RNA-seq was used to measure gene expression levels in scrambled control, PRMT5 and WDR77 short hairpin RNA (shRNA) infected human breast cancer cells
The PRMT5/WDR77 complex regulates alternative splicing through ZNF326 in breast cancer.
No sample metadata fields
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