ABSTRACT
The signaling of reactive oxygen species (ROS) is essential for the maintenance of normal cellular function. However, whether and how ROS regulate stem cells are unclear. Here, we demonstrate that, in transgenic mice expressing the human manganese superoxide dismutase (MnSOD) gene, a scavenger of ROS in mitochondria, the number and function of mouse hematopoietic stem/progenitor cells (HSPC) under physiological conditions are enhanced. Importantly, giving MnTnBuOE-2-PyP5+(MnP), a redox- active MnSOD mimetic, to mouse primary bone marrow cells or to C57B/L6 mice significantly enhances the number of HSPCs. Mechanistically, MnP reduces superoxide to hydrogen peroxide, which activates intracellular Nrf2 signaling leading to the induction of antioxidant enzymes, including MnSOD and catalase, and mitochondrial uncoupling protein 3. The results reveal a novel role of ROS signaling in regulating stem cell function, and suggest a possible beneficial effect of MnP in treating pathological bone marrow cell loss and in increasing stem cell population for bone marrow transplantation.
Subject(s)
Hematopoietic Stem Cells/physiology , Metalloporphyrins/pharmacology , Superoxide Dismutase/metabolism , Animals , Cells, Cultured , Female , Hematopoietic Stem Cells/drug effects , Humans , Hydrogen Peroxide/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mitochondria/metabolism , Reactive Oxygen Species/metabolism , Signal Transduction , Superoxide Dismutase/geneticsABSTRACT
Crystals of truncated (delta425-461) pyridoxal-5'-phosphate (PLP)-dependent mouse ornithine decarboxylase (mOrnDC') have been obtained that diffract to 2.2 angstroms resolution (P2(1)2(1)2, a = 119.5 angstroms, b = 74.3 angstroms, c = 46.1 angstroms). OrnDC produces putrescine, which is the precursor for the synthesis of polyamines in eukaryotes. Regulation of activity and understanding of the mechanism of action of this enzyme may aid in the development of compounds against cancer. mOrnDC is a member of group IV PLP-dependent decarboxylases, for which there are no known representative structures.
Subject(s)
Ornithine Decarboxylase/chemistry , Amino Acid Sequence , Animals , Crystallography, X-Ray , Eflornithine/analogs & derivatives , Eflornithine/chemistry , Enzyme Inhibitors/chemistry , Mice , Molecular Sequence Data , Ornithine Decarboxylase Inhibitors , Peptide Fragments/chemistry , Pyridoxal Phosphate/chemistry , Sequence DeletionABSTRACT
A gene encoding biodegradative ornithine decarboxylase from Lactobacillus sp. strain 30a was isolated from a genomic DNA library and sequenced. Primer extension analysis revealed two transcription initiation sites. The deduced amino acid sequence is compared with the amino acid sequences of five previously reported bacterial decarboxylases, and conserved pyridoxal phosphate motif residues are identified.
Subject(s)
Lactobacillus/genetics , Ornithine Decarboxylase/genetics , Amino Acid Sequence , Base Sequence , Conserved Sequence , Lactobacillus/enzymology , Molecular Sequence Data , Sequence Analysis, DNA , Sequence Homology, Amino AcidABSTRACT
Putrescine is the immediate precursor for the synthesis of polyamines and is normally generated by the action of ornithine decarboxylase. However, putrescine can also be produced by the conversion of arginine to agmatine by arginine decarboxylase (bADC) followed by the release of urea by agmatine ureohydrolase. Amino-acid sequence homology with the eukaryotic ornithine decarboxylases suggests that bADC may be a model for this group of decarboxylases. We report here the crystallization of arginine decarboxylase from E. coli. Crystals up to 1 mm in size are grown by vapor equilibration using Li(2)SO(4) and polyethylene glycols as precipitants. The crystals exhibit diffraction maxima beyond 3 A resolution and belong to space group P4(1(3))2(1)2 with a = 192.4 and c = 121.0 A. These unit-cell dimensions together with the estimated density of the crystals suggest the presence of one tetramer of bADC (71 kDa subunit(-1)) per asymmetric unit (V(m) = 2.0 A(3) Da(-1)).
ABSTRACT
The pathogenesis of the cardiomyopathy associated with diabetes mellitus is unknown. Among several suggested mechanisms, myocardial necrosis induced by endogenous catecholamines may play a role. Therefore, the sensitivity of the heart to the effect of varying doses of isoproterenol hydrochloride and norepinephrine bitartrate was examined in diabetic and control rats given streptozocin. The dose of isoproterenol hydrochloride ranged from 0.008 to 30 mg/kg of body weight. Norepinephrine bitartrate was given in doses from 0.2 to 1.0 mg/kg of body weight. Each dose was given twice, 24 hours apart. Animals were killed 48 hours after the first dose, and their hearts were examined pathologically. Diabetes did not significantly alter the pathological response of the heart to either drug. We conclude that the diabetic heart is not intrinsically hypersensitive to catecholamines.
