Telomere loss has been proposed as a mechanism for counting cell divisions during aging in normal somatic cells. How such a mitotic clock initiates the intracellular signalling events that culminate in G1 cell cycle arrest and senescence to restrict the lifespan of normal human cells is not known. We investigated the possibility that critically short telomere length activates a DNA damage response pathway involving p53 and p21(WAF1) in aging cells.
Numerous studies have shown that supplementation of the growth medium of human fibroblasts with dexamethasone at physiologic concentrations extends replicative lifespan up to 30%. While this extension of lifespan has been used to probe various aspects of the senescent phenotype, no mechanism for the increased lifespan of human fibroblasts grown in the presence of dexamethasone has ever been identified.
PURPOSE: To investigate the migratory and contractile behavior of isolated human corneal fibroblasts in fibrillar collagen matrices. METHODS: A telomerase-infected, extended-lifespan human corneal fibroblast cell line (HTK) was transfected by using a vector for enhanced green fluorescent protein (GFP)-alpha-actinin. Cells were plated at low density on top of or within 100-microm-thick fibrillar collagen lattices. After 18 hours to 7 days, time-lapse imaging was performed.
TOR (target of rapamycin) is a serine-threonine protein kinase that is conserved across a diverse range of species from fungi to mammals. The signaling pathway that is anchored by TOR is also conserved across species. In mammals, mTOR integrates growth factor, amino acid, nutrient and energy sensing signals, and thus plays a major role in cell growth and proliferation, protein synthesis and autophagy.
AIMS: Resveratrol, a silent information regulator 1 (SIRT1) activator, has been reported to act as an antioxidant contained in red wine and prevent the development of cardiovascular diseases. Histone deacetylase such as SIRT1 is involved in the regulation of lifespan extension. In this study, the effect of resveratrol on matrix metalloproteinases (MMPs) that play an important role in metastasis was examined in human fibrosarcoma cell line, HT1080. MAIN METHODS: The effect of resveratrol on MMPs' activity was evaluated using gelatin zymography.
BACKGROUND: Extracts of Sasa senanensis Rehder are used in traditional Japanese medicine; however, little is known about the underlying mechanisms of their potential health benefits. METHODS: S. senanensis leaves were extracted with subcritical water. An active small-molecule was isolated using reversed-phase high-performance liquid chromatography (HPLC), and identified as 3,4-dihydroxybenzaldehyde (protocatechuic aldehyde or PA). The effects of PA on the activity of histone demethylase, the Drosophila melanogaster lifespan and gene expression in Drosophila S2 cells were investigated.
The Journal of Neuroscience: The Official Journal of the Society for Neuroscience
Spinal muscular atrophy (SMA), a recessive neurodegenerative disease, is characterized by the selective loss of spinal motor neurons. No available therapy exists for SMA, which represents one of the leading genetic causes of death in childhood. SMA is caused by a mutation of the survival-of-motor-neuron 1 (SMN1) gene, leading to a quantitative defect in the survival-motor-neuron (SMN) protein expression. All patients retain one or more copies of the SMN2 gene, which modulates the disease severity by producing a small amount of stable SMN protein.
A number of neurological diseases are caused by mutations of RNA metabolism-related genes. A complicating issue is that whether under- or overfunction of such genes is responsible for the phenotype. Polyglutamine tract binding protein-1, a causative gene for X-linked mental retardation, is also involved in RNA metabolism, and both mutation and duplication of the gene were reported in human patients. In this study, we first report a novel phenotype of dPQBP1 (drosophila homolog of Polyglutamine tract binding protein-1)-mutant flies, lifespan shortening.
American Journal of Physiology. Heart and Circulatory Physiology
G protein-coupled receptor/adenylyl cyclase (AC)/cAMP signaling is crucial for all cellular responses to physiological and pathophysiological stimuli. There are nine isoforms of membrane-bound AC, with type 5 being one of the two major isoforms in the heart. Since the role of AC in the heart in regulating cAMP and acute changes in inotropic and chronotropic state are well known, this review will address our current understanding of the distinct regulatory role of the AC5 isoform in response to chronic stress.
Calorie restriction (CR) extends lifespan in a wide variety of species and mitigates diseases of aging in mammals. Here, we describe the evidence that the silent information regulator 2 (SIR2) gene, which encodes a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, regulates lifespan and mediates CR in lower species such as Saccharomyces cerevisiae and Caenorhabditis elegans. We discuss the emerging roles of mammalian SIR2 homologs in regulating physiological changes triggered by CR and their potential connections to diseases of aging.