CONTEXT: Protein glycation is the major contributing factor in the development of diabetic complications. The antiglycation potential of medicinal plants provides a promising opportunity as complementary interventions for complications. OBJECTIVE: To investigate the antiglycation potential of 19 medicinal plants extracts using albumin by estimating different indicators: (1) glycation (early and late), (2) albumin oxidation, and (3) amyloid aggregation.
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.
FOXO (Forkhead box O) transcription factors constitute an evolutionally conserved subgroup within the large Forkhead family of transcription regulators. FOXO factors are important regulators of the cell cycle, apoptosis, DNA repair, metabolism, oxidative stress resistance and longevity. Genetic studies of Caenorhabditis elegans demonstrated that FOXO factors are major targets of the insulin-like signalling implicated during the regulation of glucose metabolism and lifespan extension.
In amyotrophic lateral sclerosis (ALS), the progressive loss of motor neurons is accompanied by extensive muscle denervation, resulting in paralysis and ultimately death. Upregulation of amyloid beta (A4) precursor protein (APP) in muscle fibres coincides with symptom onset in both sporadic ALS patients and the SOD1(G93A) mouse model of familial ALS.
While the eukaryotic genome is the same throughout all somatic cells in an organism, there are specific structures and functions that discern one type of cell from another. These differences are due to the cell's unique gene expression patterns that are determined during cellular differentiation. Interestingly, these cell-specific gene expression patterns can be affected by an organism's environment throughout its lifetime leading to phenotypical changes that have the potential of altering risk of some diseases.
Poly(ADP-ribosyl)ation (PARylation) is a posttranslational protein modification (PTM) catalyzed by members of the poly(ADP-ribose) polymerase (PARP) enzyme family. PARPs use NAD(+) as substrate and upon cleaving off nicotinamide they transfer the ADP-ribosyl moiety covalently to suitable acceptor proteins and elongate the chain by adding further ADP-ribose units to create a branched polymer, termed poly(ADP-ribose) (PAR), which is rapidly degraded by poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribosylhydrolase 3 (ARH3).
A de novo G608G mutation in LMNA gene leads to Hutchinson-Gilford progeria syndrome. Mice lacking the prelamin A-processing metalloprotease, Zmpste24, recapitulate many of the progeroid features of Hutchinson-Gilford progeria syndrome. Here we show that A-type lamins interact with SUV39H1, and prelamin A/progerin exhibits enhanced binding capacity to SUV39H1, protecting it from proteasomal degradation and, consequently, increasing H3K9me3 levels. Depletion of Suv39h1 reduces H3K9me3 levels, restores DNA repair capacity and delays senescence in progeroid cells.
Under normal physiological conditions, reactive oxygen species (ROS) serve as 'redox messengers' in the regulation of intracellular signalling, whereas excess ROS may induce irreversible damage to cellular components and lead to cell death by promoting the intrinsic apoptotic pathway through mitochondria. In the aging process, accumulation of mitochondria DNA mutations, impairment of oxidative phosphorylation as well as an imbalance in the expression of antioxidant enzymes result in further overproduction of ROS.
Sir2 is an NAD-dependent deacetylase that connects metabolism with longevity in yeast, flies, and worms. Mammals have seven Sir2 homologs (SIRT1-7). We show that SIRT4 is a mitochondrial enzyme that uses NAD to ADP-ribosylate and downregulate glutamate dehydrogenase (GDH) activity. GDH is known to promote the metabolism of glutamate and glutamine, generating ATP, which promotes insulin secretion. Loss of SIRT4 in insulinoma cells activates GDH, thereby upregulating amino acid-stimulated insulin secretion.
The possibility is discussed that dietary restriction modulates ageing and onset of related pathologies by, in addition to upregulation of proteolysis, suppression of glycolysis which in turn decreases generation of methylglyoxal (MG), a highly toxic glycating agent which can provoke cellular senescence and many age-related pathologies. This proposal is supported by the observation that intermittent feeding can mimic dietary restriction's effects on mouse lifespan without any overall reduction in calorie intake.