Somatic stem cells mediate tissue maintenance for the lifetime of an organism. Despite the well-established longevity that is a prerequisite for such function, accumulating data argue for compromised stem cell function with age. Identifying the mechanisms underlying age-dependent stem cell dysfunction is therefore key to understand the aging process.
Accumulating mitochondrial DNA mutations drive premature hematopoietic aging phenotypes distinct from physiological stem cell aging.
Sex, Age, Specimen part
View SamplesMicroRNAs (miRNAs) regulate many basic aspects of cell biology including neuronal plasticity, but little is known of their roles in drug addiction. Extended access to cocaine can trigger the emergence of compulsive drug-seeking behaviors, but molecular mechanisms regulating this process remain unclear. Here we report that microRNA-212 (miR-212) is upregulated in the dorsal striatum of rats with extended access to cocaine. Striatal overexpression of miR-212 decreases, whereas its inhibition increases cocaine intake in rats with extended but not restricted drug access, suggesting that miR-212 serves as a protective factor against the development of compulsive drug seeking. The transcription factor CREB (cAMP response element-binding protein) is considered a core regulator of cocaine reward. We show that miR-212 controls responsiveness to cocaine by dramatically amplifying striatal CREB signaling. This action occurs through miR-212-enhanced Raf-1 activity, resulting in adenylyl cyclase sensitization and increased expression of the essential CREB co-activator TORC (Transducer of Regulated CREB; also known as CRTC). Our findings suggest that striatal miR-212 signaling plays a key role in vulnerability to addiction, and that noncoding RNAs such as the miRNAs may serve as novel targets for the development of anti-addiction therapeutics.
Striatal microRNA controls cocaine intake through CREB signalling.
Sex, Specimen part, Cell line
View SamplesAging of hematopoietic stem cells (HSCs) leads to several functional changes, including alterations affecting self-renewal and differentiation. While it is well established that many of the age-induced changes are intrinsic to HSCs, less is known about the stability of this state. Here, we entertained the hypothesis that HSC aging is driven by the acquisition of permanent genetic mutations. To examine this issue at a functional level in vivo, we applied induced pluripotent stem (iPS) cell reprogramming of aged hematopoietic progenitors and allowed the resulting aged-derived iPS cells to reform hematopoiesis via blastocyst complementation. Next, we functionally characterized iPS-derived HSCs in primary chimeras and following the transplantation of 're-differentiated' HSCs into new hosts; the gold standard to assess HSC function. Our data demonstrate remarkably similar functional properties of iPS-derived and endogenous blastocyst-derived HSCs, despite the extensive chronological and proliferative age of the former. Our results therefore favor a model in which an underlying, but reversible, epigenetic component is a hallmark of HSC aging rather than being driven by an increased DNA mutation burden.
An epigenetic component of hematopoietic stem cell aging amenable to reprogramming into a young state.
Specimen part
View SamplesMicroRNAs (miRNAs) have been implicated in regulating multiple processes during brain development in various species. However, the function of miRNAs in human brain development remains largely unexplored. Here, we provide a comprehensive analysis of miRNA expression of regionalized neural progenitor cells derived from human embryonic stem cells and human fetal brain. We found mir-92b-3p and mir-130b-5p to be specifically associated with neural progenitors and several miRNAs that display both age-specific and region-specific expression patterns. Among these miRNAs, we identified miR-10 to be specifically expressed in the human hindbrain and spinal cord, while absent from rostral regions. We found that miR-10 regulates a large number of genes enriched for functions including transcription, actin cytoskeleton and ephrin receptor signaling. When overexpressed, miR-10 influences caudalization of human neural progenitors cells. Together, these data confirms a role for miRNAs in establishing different human neural progenitor populations. This data set also provides a comprehensive resource for future studies investigating the functional role of different miRNAs in human brain development. Overall design: Human embryonic stem cells (hESCs) were transduced with lentiviral vectors expressing either miR10a-GFP or miR10b-GFP. The expression of the vectors is Tet-regulated and they will only be expressed in the presence of Doxycycline. In order to detect direct targets of the miR10a and miR10b, we differentiated the trasduced hESCs for 14 days, and added doxycycline to only half of the groups - resulting in groups that are overexpressing miR10a or miR10b and some groups that are not overexpressing these miRNAs.
Comprehensive analysis of microRNA expression in regionalized human neural progenitor cells reveals microRNA-10 as a caudalizing factor.
No sample metadata fields
View SamplesGenome wide RNA-seq from pGM and HSCs in response to expression of the MLL-ENL fusion gene Overall design: Examination of mRNA abundance in two cell types with or without induction of the MLL-ENL fusion gene (following 48h of culture)
Hematopoietic stem cells are intrinsically protected against MLL-ENL-mediated transformation.
No sample metadata fields
View SamplesMost metabolic studies are conducted in male animals; thus, the molecular mechanism controlling gender-specific pathways has been neglected, including sex-dependent responses to peroxisome proliferator-activated receptors (PPARs). Here we show that PPARalpha has broad female-dependent repressive actions on hepatic genes involved in steroid metabolism and inflammation. In males, this effect is reproduced by the administration of synthetic PPARalpha ligand. Using the steroid hydroxylase gene Cyp7b1 as a model, we elucidated the molecular mechanism of this PPARalpha-dependent repression. Initial sumoylation of the ligand-binding domain of PPARalpha triggers the interaction of PPARalpha with the GA-binding protein alpha bound to the target promoter. Histone deacetylase is then recruited, and histones and adjacent Sp1-binding site are methylated. These events result in the loss of Sp1-stimulated expression, and thus the down-regulation of Cyp7b1. Physiologically, this repression confers protection against estrogen-induced intrahepatic cholestasis, paving the way for a novel therapy against the most common hepatic disease during pregnancy.
Sumoylated PPARalpha mediates sex-specific gene repression and protects the liver from estrogen-induced toxicity in mice.
No sample metadata fields
View SamplesWe used microarray technology to profile mRNA expression in the skeletal muscle of normal (NGT), glucose intolerant (IGT) and type 2 diabetic (DM) subjects. Groups were classified using WHO criteria and, importantly, the DM group were free of anti hypoglycaemic medication for one week prior to biopsy.
Integration of microRNA changes in vivo identifies novel molecular features of muscle insulin resistance in type 2 diabetes.
Sex, Age
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 SamplesInborn errors of lipid metabolism illustrate the importance of proper milk fat oxidation in newborn mammals. In the liver, a remarkable lipid catabolic competence is present at birth; however, it is unclear how this critical trait is acquired and regulated. In this work, we found that the genes required for milk lipid catabolism are already transcribed before birth in the term fetus (E19.5) and controlled by the peroxisome-proliferator activated receptor alpha (PPAR) in mouse liver. The developmental activity of PPAR strongly regulates fatty acid oxidation genes. Two days after birth (P2), during milk suckling, PPAR-null mice develop a congenital steatosis and milk protein oxidation is de-repressed to fuel an alternative energy pathway that maintains glucose homeostasis and postnatal growth. Our results demonstrate for the first time, the developmental role of PPAR in regulating the metabolic ability to use maternal milk as fuel in the early days of life.
Glucocorticoid receptor-PPARα axis in fetal mouse liver prepares neonates for milk lipid catabolism.
Specimen part
View SamplesInborn errors of lipid metabolism illustrate the importance of proper milk fat oxidation in newborn mammals. In the liver, a remarkable lipid catabolic competence is present at birth; however, it is unclear how this critical trait is acquired and regulated. In this work, we found that the genes required for milk lipid catabolism are already transcribed before birth in the term fetus (E19.5) and controlled by the peroxisome-proliferator activated receptor alpha (PPAR) in mouse liver. The developmental activity of PPAR strongly regulates fatty acid oxidation genes. Two days after birth (P2), during milk suckling, PPAR-null mice develop a congenital steatosis and milk protein oxidation is de-repressed to fuel an alternative energy pathway that maintains glucose homeostasis and postnatal growth. Our results demonstrate for the first time, the developmental role of PPAR in regulating the metabolic ability to use maternal milk as fuel in the early days of life.
Glucocorticoid receptor-PPARα axis in fetal mouse liver prepares neonates for milk lipid catabolism.
Sex, Specimen part
View Samples