The skin interfollicular epidermis (IFE) is the first barrier against the external environment and its maintenance is critical for survival. Two seemingly opposite theories have been proposed to explain IFE homeostasis. One posits that IFE is maintained by a long-lived slow-cycling stem cell (SC) population that give rise to short-lived transit-amplifying (TA) cell progeny, while the other suggests that homeostasis is achieved by a single committed progenitor (CP) that balances stochastic fate. Here, we probed the cellular heterogeneity within the IFE using two different inducible CREER targeting IFE progenitors. Quantitative analysis of clonal fate data and proliferation dynamics demonstrate the existence of two distinct proliferative cell compartments composed of slow-cycling SC and CP, both of which undergo population asymmetric self-renewal. However, following wounding, only SCs contribute substantially to the repair and long-term regeneration of the tissue, while CP cells make a minimal and transient contribution.
Distinct contribution of stem and progenitor cells to epidermal maintenance.
Specimen part
View SamplesStudy objectives: Chronic obstructive pulmonary disease and obstructive sleep apnea overlap syndrome is associated with excess mortality, and outcomes are related to the degree of hypoxemia. People at high altitude are susceptible to periodic breathing, and hypoxia at altitude is associated with cardio-metabolic dysfunction. Hypoxemia in these scenarios may be described as superimposed sustained plus intermittent hypoxia, or overlap hypoxia (OH), the effects of which have not been investigated. We aimed to characterize the cardio-metabolic consequences of OH in mice. Methods: C57BL/6J mice were subjected to either sustained hypoxia (SH, FiO2=0.10), intermittent hypoxia (IH, FiO2=0.21 for 12 hours, and FiO2 oscillating between 0.21 and 0.06, 60 times/hour, for 12 hours), OH (FiO2=0.13 for 12 hours, and FiO2 oscillating between 0.13 and 0.06, 60 times/hour, for 12 hours), or room air (RA), n=8/group. Blood pressure and intraperitoneal glucose tolerance test were measured serially, and right ventricular systolic pressure (RVSP) was assessed. Results: Systolic blood pressure transiently increased in IH and OH relative to SH and RA. RVSP did not increase in IH, but increased in SH and OH by 52% (p<0.001) and 20% (p=0.001). Glucose disposal worsened in IH and improved in SH, with no change in OH. Serum LDL and VLDL increased in OH and SH, but not in IH. Hepatic oxidative stress increased in all hypoxic groups, with the highest increase in OH. Conclusions: Overlap hypoxia may represent a unique and deleterious cardio-metabolic stimulus, causing systemic and pulmonary hypertension, and without protective metabolic effects characteristic of sustained hypoxia. Overall design: Whole liver mRNA profiles of C57BL/6J mice exposed to RA, SH, IH, or OH.
Combined intermittent and sustained hypoxia is a novel and deleterious cardio-metabolic phenotype.
Age, Specimen part, Genotype, Treatment, Subject
View SamplesIschemic tolerance can be induced by numerous preconditioning stimuli, including various Toll-like receptor (TLR) ligands. We have shown previously that systemic administration of the TLR4 ligand, lipopolysaccharide (LPS) or the TLR9 ligand, unmethylated CpG ODNs prior to transient brain ischemia in mice confers substantial protection against ischemic damage. To elucidate the molecular mechanisms of preconditioning, we compared brain and blood genomic profiles in response to preconditioning with these TLR ligands and to preconditioning via exposure to brief ischemia.
Multiple preconditioning paradigms converge on interferon regulatory factor-dependent signaling to promote tolerance to ischemic brain injury.
Specimen part, Treatment
View SamplesGene expression profiling of newborn lung tissue revealed few changes in compound FGFR3/FGFR4 deficient mice, consistent with their normal lung morphology at birth, suggesting the sequence of events leading to the phenotype initiates after birth in this model.
Fibroblast growth factor receptors control epithelial-mesenchymal interactions necessary for alveolar elastogenesis.
Age, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Jumonji modulates polycomb activity and self-renewal versus differentiation of stem cells.
Specimen part
View SamplesWe used microarrays to detail the role of JMJ in ES cell function.
Jumonji modulates polycomb activity and self-renewal versus differentiation of stem cells.
Specimen part
View SamplesThe spatial organization of DNA in the cell nucleus is an emerging key contributor to genomic function. We have developed 4C technology, or 3C-on-chip, which allows for an unbiased genome-wide search for DNA loci that contact a given locus in the nuclear space. We demonstrate here that active and inactive genes are engaged in many long-range intrachromosomal interactions and can also form interchromosomal contacts. The active b-globin locus in fetal liver contacts mostly transcribed, but not necessarily tissue-specific, loci elsewhere on chromosome 7, while the inactive locus in fetal brain contacts different, transcriptionally silent, loci. A housekeeping gene in a gene dense region on chromosome 8 forms long-range contacts predominantly with other active gene clusters, both in cis and in trans, and many of these intra- and interchromosomal interactions are conserved between the tissues analyzed. Our data demonstrate that chromosomes fold into areas of active chromatin and areas of inactive chromatin and establish 4C technology as a powerful tool to study nuclear architecture.
Nuclear organization of active and inactive chromatin domains uncovered by chromosome conformation capture-on-chip (4C).
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Knockout of G protein β5 impairs brain development and causes multiple neurologic abnormalities in mice.
Specimen part
View SamplesJournal : Blood. 2009 Jul 9;114(2):469-77. Epub 2009 May 13.
Endothelial deletion of hypoxia-inducible factor-2alpha (HIF-2alpha) alters vascular function and tumor angiogenesis.
Specimen part
View SamplesMammalian genomes contain numerous DNA elements with potential transcription regulatory function but unknown target genes. We used transgenic, gain-of-function mice with an ectopic copy of the beta-globin locus control region (LCR) to better understand how regulatory elements dynamically search the genome for target genes. We find that the LCR samples a restricted nuclear sub-volume in which it forms preferential contacts with genes controlled by shared transcription factors. One contacted gene, betah1, located on another chromosome, is upregulated, providing genetic demonstration that mammalian enhancers can function between chromosomes. Upregulation is not pan-cellular but confined to selected jackpot cells significantly enriched for inter-chromosomal LCR-betah1 interactions. This implies that long-range DNA contacts are relatively stable and cell-specific and, when functional, cause variegated expression. We refer to this as spatial effect variegation (SEV). The data provide a dynamic and mechanistic framework for enhancer action, important for assigning function to the one- and three-dimensional structure of DNA.
Variegated gene expression caused by cell-specific long-range DNA interactions.
Specimen part, Disease
View Samples