The P7C3 class of neuroprotective aminopropyl carbazoles has been shown to block neuronal cell death in models of neurodegeneration. We now show that P7C3 molecules additionally preserve axonal ...integrity after injury, before neuronal cell death occurs, in a rodent model of blast-mediated traumatic brain injury (TBI). This protective quality may be linked to the ability of P7C3 molecules to activate nicotinamide phosphoribosyltransferase, the rate-limiting enzyme in nicotinamide adenine dinucleotide salvage. Initiation of daily treatment with our recently reported lead agent, P7C3-S243, 1 day after blast-mediated TBI blocks axonal degeneration and preserves normal synaptic activity, learning and memory, and motor coordination in mice. We additionally report persistent neurologic deficits and acquisition of an anxiety-like phenotype in untreated animals 8 months after blast exposure. Optimized variants of P7C3 thus offer hope for identifying neuroprotective agents for conditions involving axonal damage, neuronal cell death, or both, such as occurs in TBI.
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•Treatment with (−)-P7C3-S243 after blast injury blocks widespread axonal degeneration•Treatment with (−)-P7C3-S243 after blast injury preserves learning and memory•Treatment with (−)-P7C3-S243 after blast injury preserves motor coordination•Without treatment, neuropsychiatric deficits persist chronically after blast injury
Blast exposure from explosive devices elicits traumatic brain injury associated with neurodegeneration, cognitive and motor decline, and psychiatric symptoms. Yin et al. now show that treatment with the neuroprotective agent (−)-P7C3-S243 24 hr after blast injury blocks axonal degeneration in the brain and preserves normal learning, memory, and motor coordination. Neuropsychiatric symptoms persist chronically in untreated mice. Optimized P7C3 variants offer hope for identifying neuroprotective agents for conditions involving axonal damage, neuronal cell death, or both.
Please Keep Me 2uned to PKM2 McKnight, Steven L.
Molecular cell,
03/2014, Letnik:
53, Številka:
5
Journal Article
Recenzirano
Odprti dostop
In this issue of Molecular Cell, Keller et al. (2014) found that binding of the metabolite SAICAR to PKM2 induces the protein kinase activity of an enzyme normally designed to terminate the ...glycolytic pathway.
When prototrophic yeast cells are cultured under nutrient-limited conditions that mimic growth in the wild, rather than in the high-glucose solutions used in most laboratory studies, they exhibit a ...robustly periodic metabolic cycle. Over a cycle of 4 to 5 hours, yeast cells rhythmically alternate between glycolysis and respiration. The cell division cycle is tightly constrained to the reductive phase of this yeast metabolic cycle, with DNA replication taking place only during the glycolytic phase. We show that cell cycle mutants impeded in metabolic cycle-directed restriction of cell division exhibit substantial increases in spontaneous mutation rate. In addition, disruption of the gene encoding a DNA checkpoint kinase that couples the cell division cycle to the circadian cycle abolishes synchrony of the metabolic and cell cycles. Thus, circadian, metabolic, and cell division cycles may be coordinated similarly as an evolutionarily conserved means of preserving genome integrity.
We previously reported the discovery of P7C3, an aminopropyl carbazole having proneurogenic and neuroprotective properties in newborn neural precursor cells of the dentate gyrus. Here, we provide ...evidence that P7C3 also protects mature neurons in brain regions outside of the hippocampus. P7C3 blocks 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-mediated cell death of dopaminergic neurons in the substantia nigra of adult mice, a model of Parkinson disease (PD). Dose–response studies show that the P7C3 analog P7C3A20 blocks cell death with even greater potency and efficacy, which parallels the relative potency and efficacy of these agents in blocking apoptosis of newborn neural precursor cells of the dentate gyrus. P7C3 and P7C3A20 display similar relative effects in blocking 1-methyl-4-phenylpyridinium (MPP ⁺)-mediated death of dopaminergic neurons in Caenorhabditis elegans , as well as in preserving C. elegans mobility following MPP ⁺ exposure. Dimebon, an antihistaminergic drug that is weakly proneurogenic and neuroprotective in the dentate gyrus, confers no protection in either the mouse or the worm models of PD. We further demonstrate that the hippocampal proneurogenic efficacy of eight additional analogs of P7C3 correlates with their protective efficacy in MPTP-mediated neurotoxicity. In vivo screening of P7C3 analogs for proneurogenic efficacy in the hippocampus may thus provide a reliable means of predicting neuroprotective efficacy. We propose that the chemical scaffold represented by P7C3 and P7C3A20 provides a basis for optimizing and advancing pharmacologic agents for the treatment of patients with PD.
We previously reported the discovery of P7C3, an aminopropyl carbazole having proneurogenic and neuroprotective properties in newborn neural precursor cells of the hippocampal dentate gyrus. We have ...further found that chemicals having efficacy in this in vivo screening assay also protect dopaminergic neurons of the substantia nigra following exposure to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, a mouse model of Parkinson disease. Here, we provide evidence that an active analog of P7C3, known as P7C3A20, protects ventral horn spinal cord motor neurons from cell death in the G93A-SOD1 mutant mouse model of amyotrophic lateral sclerosis (ALS). P7C3A20 is efficacious in this model when administered at disease onset, and protection from cell death correlates with preservation of motor function in assays of walking gait and in the accelerating rotarod test. The prototypical member of this series, P7C3, delays disease progression in G93A-SOD1 mice when administration is initiated substantially earlier than the expected time of symptom onset. Dimebon, an antihistaminergic drug with significantly weaker proneurogenic and neuroprotective efficacy than P7C3, confers no protection in this ALS model. We propose that the chemical scaffold represented by P7C3 and P7C3A20 may provide a basis for the discovery and optimization of pharmacologic agents for the treatment of ALS.
The dominant structural feature of intermediate filament (IF) proteins is a centrally located α-helix. These long α-helical segments become paired in a parallel orientation to form coiled-coil ...dimers. Pairs of dimers further coalesce in an anti-parallel orientation to form tetramers. These early stages of intermediate filament assembly can be accomplished solely by the central α-helices. By contrast, the assembly of tetramers into mature intermediate filaments is reliant upon an N-terminal head domain. IF head domains measure roughly 100 amino acids in length and have long been understood to exist in a state of structural disorder. Here, we describe experiments favoring the unexpected idea that head domains self-associate to form transient structural order in the form of labile cross-β interactions. We propose that this weak form of protein structure allows for dynamic regulation of IF assembly and disassembly. We further offer that what we have learned from studies of IF head domains may represent a simple, unifying template for understanding how thousands of other intrinsically disordered proteins help to establish dynamic morphological order within eukaryotic cells.
Budding yeast undergo robust oscillations in oxygen consumption during continuous growth in a nutrient-limited environment. Using liquid chromatography-mass spectrometry and comprehensive 2D gas ...chromatography-mass spectrometry-based metabolite profiling methods, we have determined that the intracellular concentrations of many metabolites change periodically as a function of these metabolic cycles. These results reveal the logic of cellular metabolism during different phases of the life of a yeast cell. They may further indicate that oscillation in the abundance of key metabolites might help control the temporal regulation of cellular processes and the establishment of a cycle. Such oscillations in metabolic state might occur during the course of other biological cycles.
The low-complexity (LC) domain of the fused in sarcoma (FUS) RNA binding protein self-associates in a manner causing phase separation from an aqueous environment. Incubation of the FUS LC domain ...under physiologically normal conditions of salt and pH leads to rapid formation of liquid-like droplets that mature into a gel-like state. Both examples of phase separation have enabled reductionist biochemical assays allowing discovery of an N-terminal region of 57 residues that assembles into a labile, cross-β structure. Here we provide evidence of a nonoverlapping, C-terminal region of the FUS LC domain that also forms specific cross-β interactions. We propose that biologic function of the FUS LC domain may operate via the mutually exclusive use of these N- and C-terminal cross-β cores. Neurodegenerative disease-causing mutations in the FUS LC domain are shown to imbalance the two cross-β cores, offering an unanticipated concept of LC domain function and dysfunction.
Clock:BMAL1 and NPAS2:BMAL1 are heterodimeric transcription factors that control gene expression as a function of the light-dark cycle. Although built to fluctuate at or near a 24-hour cycle, the ...clock can be entrained by light, activity, or food. Here we show that the DNA-binding activity of the Clock:BMAL1 and NPAS2:BMAL1 heterodimers is regulated by the redox state of nicotinamide adenine dinucleotide (NAD) cofactors in a purified system. The reduced forms of the redox cofactors, NAD(H) and NADP(H), strongly enhance DNA binding of the Clock:BMAL1 and NPAS2:BMAL1 heterodimers, whereas the oxidized forms inhibit. These observations raise the possibility that food, neuronal activity, or both may entrain the circadian clock by direct modulation of cellular redox state.
Mouse ES cells use a mitochondrial threonine dehydrogenase (TDH) enzyme to catabolize threonine into glycine and acetyl-CoA. Measurements of mRNA abundance have given evidence that ES cells express ...upwards of 1,000-fold higher levels of TDH mRNA than any of seven other mouse tissues tested. When cell culture medium is deprived of threonine, ES cells rapidly discontinue DNA synthesis, arrest cell division, and eventually die. Such studies led to the conclusion that mouse ES cells exist in a threonine-dependent metabolic state. Proceeding with the assumption that the active TDH enzyme should be essential for the growth and viability of mouse ES cells, we performed a drug screen in search of specific inhibitors of the purified TDH enzyme. Such efforts led to the discovery of a class of quinazolinecarboxamide (Qc) compounds that inhibit the ability of the TDH enzyme to catabolize threonine into glycine and acetyl-CoA. Administration of Qc inhibitors of TDH to mouse ES cells impeded cell growth and resulted in the induction of autophagy. By contrast, the same chemicals failed to affect the growth of HeLa cells at concentrations 300-fold higher than that required to kill mouse ES cells. It was likewise observed that the Qc class of TDH inhibitors failed to affect the growth or viability of ES cell-derived embryoid body cells known to have extinguished TDH expression. These studies demonstrate how it is possible to kill a specific mammalian cell type on the basis of its specialized metabolic state.
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