The role of Tfr1 in non-erythroid tissues remains elusive due to the embryonic lethality of the Tfr1 global knockout mouse model. To bypass this problem, we generated a mouse model in which Tfr1 was conditionally deleted in intestinal epithelial cells (IECs). These mice developed severe IEC disruption, characterized by blunted villi, edema, loss of proliferative intervillus IECs, accumulation of lipids, and early neonatal lethality. Strikingly, a wide range of genes associated with epithelial-to-mesenchymal transition were highly upregulated in IEC lacking Tfr1. Additionally, candidate vesicular transport and sorting genes implicated in lipid absorption and trafficking were downregulated. Surprisingly, the presence of a mutant allele of Tfr1, which is unable to bind to iron-loaded transferrin, was capable of rescuing the lethality, intestinal epithelial homeostasis, and proliferation in a majority of the Tfr1 conditional knockout mice.
Noncanonical role of transferrin receptor 1 is essential for intestinal homeostasis.
Specimen part
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Gene-chip studies of adipogenesis-regulated microRNAs in mouse primary adipocytes and human obesity.
Age, Specimen part
View SamplesAdipose tissue abundance relies partly on the factors that regulate adipogenesis, i.e. proliferation and differentiation of adipocytes. While the transcriptional program that initiates adipogenesis is well-known, the importance of microRNAs in adipogenesis is less well studied. We thus set out to investigate whether miRNAs would be actively modulated during adipogenesis and obesity. Several models exist to study adipogenesis in vitro, of which the cell line 3T3-L1 is probably the most well known, albeit not the most physiologically appropriate. We used a microarray strategy to provide a global profile of miRNAs in brown and white primary murine adipocytes (prior to and following differentiation) and evaluated the similarity of the responses to non-primary cell models, through literature data-mining. We found 65 miRNAs regulated during in vitro adipogenesis in primary adipocytes. When we compared our primary adipocyte profiles with those of cell lines reported in the literature, we found a high degree of difference in adipogenesis-regulated miRNAs. We evaluated the expression of 10 of our adipogenesis-regulated miRNAs using real-time qPCR and then selected 5 miRNAs that showed robust expression levels and profiled these by qPCR in subcutaneous adipose tissue of 20 humans with a range of body mass indices (BMI, range=21-48). Of the miRNAs tested, mir-21 was both highly expressed in human adipose tissue and positively correlated with BMI (R2=0.49, p<0.001). In conclusion, we provide the preliminary analysis of miRNAs important for primary cell in vitro adipogenesis and find that the inflammation-associated miRNA, mir-21, is up-regulated in subcutaneous adipose tissue in human obesity.
Gene-chip studies of adipogenesis-regulated microRNAs in mouse primary adipocytes and human obesity.
Age
View SamplesTo examine changes in gene expression that might occur in CNS glial cells in response to the secreted products of immune cells, we used gene array analysis to assess the early effects of different cytokine mixtures on rat mixed CNS glia in culture. We compared effects at 6 hours of cytokines typical of Th1 and Th2 lymphocytes, and monocyte marophages (M/M).. We found unique patterns of changes in gene expression for each of the three cytokine mixtures, including changes in immune-related molecules, neurotrophins, growth factors, proteins involved in axon/glial interactions, ion channels, neurotransmitters, mitochondrial function and apoptosis. These changes may have relevance in neuroprotective or damaging mechanisms in neurodegenerative diseases such as multiple sclerosis, specifically with regard to formation, repair or inhibition of lesion formation.
Differential effects of Th1, monocyte/macrophage and Th2 cytokine mixtures on early gene expression for glial and neural-related molecules in central nervous system mixed glial cell cultures: neurotrophins, growth factors and structural proteins.
No sample metadata fields
View SamplesTranscriptional programming of cell identity promises to open up new frontiers in regenerative medicine by enabling the efficient production of clinically relevant cell types. We examine if such cellular programming is accomplished by transcription factors that each have an independent and additive effect on cellular identity, or if programming factors synergize to produce an effect that is not independently obtainable. The combinations of Ngn2-Isl1-Lhx3 and Ngn2-Isl1-Phox2a transcription factors program embryonic stem cells to express a spinal or cranial motor neuron identity respectively. The two alternate expression programs are determined by recruitment of Isl1/Lhx3 and Isl1/Phox2a pairs to distinct genomic locations characterized by two alternative dimeric homeobox motifs. These results suggest that the function of programming modules relies on synergistic interactions among transcription factors and thus cannot be extrapolated from the study of individual transcription factors in a different cellular context.
Synergistic binding of transcription factors to cell-specific enhancers programs motor neuron identity.
Cell line, Treatment
View SamplesBRCA1 nestin CRE conditional knockout cortrices of P7 animals were compared to wildtype littermates to characterize the mutant phenotype.
BRCA1 tumour suppression occurs via heterochromatin-mediated silencing.
No sample metadata fields
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Foxl2 functions in sex determination and histogenesis throughout mouse ovary development.
Sex, Subject
View SamplesComparison of Foxl2-null ovaries to wildtype ovaries, ovaries lacking Wnt4 or Kit, or testes, throughout mouse development.
Foxl2 functions in sex determination and histogenesis throughout mouse ovary development.
No sample metadata fields
View SamplesAttainment of a brown adipocyte cell phenotype in white adipocytes, with their abundant mitochondria and increased energy expenditure potential, is a legitimate strategy for combating obesity. The unique transcriptional regulators of the primary brown adipocyte phenotype are unknown, limiting our ability to promote brown adipogenesis over white. In the present work, we used microarray analysis strategies to study primary preadipocytes, and we made the striking discovery that brown preadipocytes demonstrate a myogenic transcriptional signature, whereas both brown and white primary preadipocytes demonstrate signatures distinct from those found in immortalized adipogenic models. We found a plausible SIRT1-related transcriptional signature during brown adipocyte differentiation that may contribute to silencing the myogenic signature. In contrast to brown preadipocytes or skeletal muscle cells, white preadipocytes express Tcf21, a transcription factor that has been shown to suppress myogenesis and nuclear receptor activity. In addition, we identified a number of developmental genes that are differentially expressed between brown and white preadipocytes and that have recently been implicated in human obesity. The interlinkage between the myocyte and the brown preadipocyte confirms the distinct origin for brown versus white adipose tissue and also represents a plausible explanation as to why brown adipocytes ultimately specialize in lipid catabolism rather than storage, much like oxidative skeletal muscle tissue.
Myogenic gene expression signature establishes that brown and white adipocytes originate from distinct cell lineages.
No sample metadata fields
View SamplesCold triggers VEGF dependent but hypoxia independent angiogenesis in adipose tissues and anti-VEGF agents modulate adipose metabolism
Hypoxia-independent angiogenesis in adipose tissues during cold acclimation.
Sex
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