Skeletal muscle aging results in a gradual loss of skeletal muscle mass, skeletal muscle function and decreased regenerative capacity, which can lead to sarcopenia and increased mortality. While the mechanisms underlying sarcopenia remain unclear, the skeletal muscle stem cell, or satellite cell, is required for muscle regeneration. Therefore, identification of signaling pathways affecting satellite cell function during aging may provide insights into therapeutic targets for combating sarcopenia. Here, we show that a cell-autonomous loss in self-renewal occurs via novel alterations in FGF and p38 MAPK signaling in old satellite cells. We further demonstrate that pharmacological manipulation of these pathways can ameliorate age-associated self-renewal defects. Thus, our data highlight an age-associated deregulation of a satellite cell homeostatic network and reveals potential therapeutic opportunities for the treatment of progressive muscle wasting.
p38 MAPK signaling underlies a cell-autonomous loss of stem cell self-renewal in skeletal muscle of aged mice.
Specimen part
View SamplesOverexpression of p21 in NEMOhepa animals protects against DNA damage, acceleration of hepatocarcinogenesis and cholestasis. As strengthened by our LPS stimulation experiments, we identified a novel protective role of p21 against DNA damage.
p21 ablation in liver enhances DNA damage, cholestasis, and carcinogenesis.
Sex, Specimen part
View SamplesNeurotrophins are growth factors that are known to have a role in promoting cell survival and differentiation. The focus of the current study is to examine the role of neurotrophins in regulating ovarian primordial follicle development. Ovaries from 4-day old rats were placed into organ culture and cultured for 10 days in the absence or presence of neurotrophin-3 (NT3), brain-derived neurotrophic factor (BDNF), or nerve growth factor (NGF). Treatment of ovaries with NT3 resulted in a significant (P<0.01) increase in primordial follicle development (i.e. primordial to primary follicle transition). Treatment with BDNF at high doses of 100250 ng/ml also significantly (P<0.01) increased primordial follicle development, but NGF had no effect. Immunohistochemical studies determined that NT3 was present in granulosa cells, interstitial tissue, and in the oocytes of primordial and primary follicles. The NT3 receptor NTRK3 was present in oocytes at all stages of development. Analysis of ovaries that contain predominantly primordial follicles demonstrated the transcripts for NT3, NTRK3, NGF, and the BDNF/neurotrophin-4 (NT4) receptor NTRK2 are expressed, while BDNF, NT4, and the NGF receptor NTRK1 are not detectable. Inhibition of the NTRK3 receptor with the tyrophostin AG 879 resulted in oocyte death and a significant (P<0.01) reduction in follicle pool size. Inhibition of the NTRK receptors with K252a slowed primordial to primary follicle transition. A microarray analysis demonstrated that a small number of genes were differentially expressed after NT3 treatment. Observations indicate that the neurotrophin NT3, acting through the NTRK3 receptor in oocytes, promotes the primordial to primary follicle transition. Reproduction (2009) 138, pp. 697-707
Neurotrophin NT3 promotes ovarian primordial to primary follicle transition.
Sex, Specimen part
View SamplesFemale fertility is determined in part by the size and development of the primordial follicle pool. The current study investigates the role of glial cell-line derived neurotrophic factor (GDNF) in the regulation of primordial follicle development in the ovary. Ovaries from four-day old female rat pups were maintained in organ culture for ten days in the absence (control) or presence of GDNF or kit ligand/stem cell factor (KL). Ovaries treated with GDNF contained a significant increase in developing follicles, similar to that observed with KL treatment previously shown to promote follicle development. The actions of GDNF on the ovarian transcriptome were investigated with a microarray analysis. Immunohistochemical studies demonstrated that GDNF is localized to oocyte cytoplasm in follicles of all developmental stages, as well as to cumulus granulosa cells and theca cells in antral follicles. GDNF receptor alpha 1 (GFRalpha1) staining was localized to oocyte cytoplasm of primordial and primary follicles, and at reduced levels in oocytes of antral follicles. GFRalpha1 was present in mural granulosa cells of antral follicles, theca cells, and the ovarian surface epithelium. The localization studies were confirmed with molecular analysis. Microarray analysis was used to identify changes in the ovarian transcriptome and further elucidate the signaling network regulating early follicle development. Observations indicate that GDNF promotes primordial follicle development and mediates autocrine and paracrine cell-cell interactions required during folliculogenesis. In contrast to the testis, ovarian GDNF is predominantly produced by germ cells (oocytes) rather than somatic cells.
Glial-derived neurotrophic factor promotes ovarian primordial follicle development and cell-cell interactions during folliculogenesis.
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View SamplesBackground. Juvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the hormones source. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet addresses whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a recent genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging.
Juvenile hormone regulation of Drosophila aging.
Sex
View SamplesInterferon (IFN) beta-1a is an approved treatment for relapsing remitting multiple sclerosis (RRMS) and has been examined for use in secondary progressive multiple sclerosis (SPMS). However, no information regarding blood transcriptional changes induced by IFN treatment in SPMS patients is available.
Transcriptional response to interferon beta-1a treatment in patients with secondary progressive multiple sclerosis.
Sex, Age, Treatment
View SamplesAbove ground tissue of 10 day old Arabidopsis seedlings of Col wild-type, 35S-ARR7, arr7, 35S-ARR15 was treated with Cytokinin (benzyladenine), Auxin (indole-3-acetic acid) or both.
Hormonal control of the shoot stem-cell niche.
Age, Specimen part, Treatment
View SamplesActivation of the MLL-ENL-ERtm oncogene initiates aberrant proliferation of myeloid progenitors. Here, we show induction of a fail-safe mechanism mediated by the DNA damage response (DDR) machinery that results in activation of the ATR/ATM-Chk1/Chk2-p53/p21 checkpoint and cellular senescence at early stages of cellular transformation caused by a regulatable MLL-ENL-ERtm in mice. Furthermore, we identified the transcription program underlying this intrinsic anti-cancer barrier, and DDR-induced inflammatory regulators that fine-tune the signaling towards senescence, thereby modulating the fate of MLL-ENL-immortalized cells in a tissue-environment-dependent manner. Our results indicate that DDR is a rate-limiting event for acquisition of stem cell-like properties in MLL-ENL-ERtm-mediated transformation, as experimental inhibition of the barrier accelerated the transition to immature cell states and acute leukemia development.
DNA damage response and inflammatory signaling limit the MLL-ENL-induced leukemogenesis in vivo.
Specimen part, Disease stage
View SamplesAtIPT8/pga22 seedlings (gain-of-function mutant in Ws background; Sun et al. 2003, Plant Physiology 131, pp167-176) were grown on vertical plates for 7 days in LD. The seedlings were then incubated directly on the plate with medium containing 5 uM 17-beta-estradiol (for induction of the IPT8 gene) or 5 uM trans-zeatin for 12 and 24 h. 5 mm primary root tips were harvested from the seedlings and pooled for microarray analysis. Total RNA was isolated from the samples with the RNeasy Plant Mini Kit from Qiagen.
Cytokinin regulation of auxin synthesis in Arabidopsis involves a homeostatic feedback loop regulated via auxin and cytokinin signal transduction.
Specimen part, Treatment
View SamplesPurpose: Mutations in several genetic loci lead to cardiac anomalies, with mutations in transcription factor NKX2-5 gene being one of the largest mutations known. Gestational hypoxia, such as seen in high-altitude pregnancy, has been known to affect cardiac development, and this paper aims to uncover information about the underlying mechanisms of this phenomena. Methods: Wild-type female mice were mated with Nkx2-5 mutant males, to produce offsprings. The pregnant females were then separated into two groups, one left in normal air and one breathing hypoxic, 14% oxygen, air from gestation day 10.5 to 12.5. Hearts were dissected from E12.5 embryos, subjected to RNA purification followed by RNA-seq. Wild-hypoxia and mutant-normoxia were compared to control wild-normoxia. Conclusions: The results of our study provide insights into a common molecular mechanism underlying non-genetic/epigenetic and genetic cardiac anomalies. Overall design: Embryonic mice were produced with either wild-type or mutant genomes, and some from each group were exposed to hypoxia during gestation, then physical analysis and RNA sequencing was done on the embryos.
Mechanism Sharing Between Genetic and Gestational Hypoxia-Induced Cardiac Anomalies.
Specimen part, Treatment, Subject
View Samples