RESUMEN
Rothmund-Thomson syndrome (RTS) is an autosomal recessive genetic disorder characterized by poikiloderma, small stature, skeletal anomalies, sparse brows/lashes, cataracts, and predisposition to cancer. Type 2 RTS patients with biallelic RECQL4 pathogenic variants have multiple skeletal anomalies and a significantly increased incidence of osteosarcoma. Here, we generated RTS patient-derived induced pluripotent stem cells (iPSCs) to dissect the pathological signaling leading to RTS patient-associated osteosarcoma. RTS iPSC-derived osteoblasts showed defective osteogenic differentiation and gain of in vitro tumorigenic ability. Transcriptome analysis of RTS osteoblasts validated decreased bone morphogenesis while revealing aberrantly upregulated mitochondrial respiratory complex I gene expression. RTS osteoblast metabolic assays demonstrated elevated mitochondrial respiratory complex I function, increased oxidative phosphorylation (OXPHOS), and increased ATP production. Inhibition of mitochondrial respiratory complex I activity by IACS-010759 selectively suppressed cellular respiration and cell proliferation of RTS osteoblasts. Furthermore, systems analysis of IACS-010759-induced changes in RTS osteoblasts revealed that chemical inhibition of mitochondrial respiratory complex I impaired cell proliferation, induced senescence, and decreased MAPK signaling and cell cycle associated genes, but increased H19 and ribosomal protein genes. In summary, our study suggests that mitochondrial respiratory complex I is a potential therapeutic target for RTS-associated osteosarcoma and provides future insights for clinical treatment strategies.
Asunto(s)
Complejo I de Transporte de Electrón/genética , Osteosarcoma/genética , ARN Largo no Codificante/genética , RecQ Helicasas/genética , Síndrome Rothmund-Thomson/genética , Adenosina Trifosfato/biosíntesis , Proliferación Celular/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Senescencia Celular/genética , Complejo I de Transporte de Electrón/antagonistas & inhibidores , Regulación del Desarrollo de la Expresión Génica/genética , Humanos , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Células Madre Pluripotentes Inducidas/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Mutación/genética , Osteoblastos/efectos de los fármacos , Osteogénesis/genética , Osteosarcoma/complicaciones , Osteosarcoma/patología , Oxadiazoles/farmacología , Fosforilación Oxidativa/efectos de los fármacos , Piperidinas/farmacología , Síndrome Rothmund-Thomson/complicaciones , Síndrome Rothmund-Thomson/patologíaRESUMEN
While high-fat diets are associated with rising incidence of obesity/type-2 diabetes and can induce metabolic and cognitive deficits, sex-dependent comparisons are rarely systematically made. Effects of exclusive consumption of a high-fat diet (HFD) on systemic metabolism and on behavioral measures of hippocampal-dependent memory were compared in young male and female LE rats. Littermates were fed from weaning either a HFD or a control diet (CD) for 12 wk prior to testing. Sex-different effects of the HFD were observed in classic metabolic signs associated with type-2 diabetes. Males fed the HFD became obese, and had elevated fasted blood glucose levels, elevated corticosterone, and impaired glucose-tolerance, while females on the HFD exhibited only elevated corticosterone. Regardless of peripheral metabolism alteration, rats of both sexes fed the HFD were equally impaired in a spatial object recognition memory task associated with impaired hippocampal function. While the metabolic changes reported here have been characterized previously in males, the set of diet-induced effects observed here in females are novel. Impaired memory can have significant cognitive consequences, over the short-term and over the lifespan. A significant need exists for comparative research into sex-dependent differences underlying obesity and metabolic syndromes relating systemic, cognitive, and neural plasticity mechanisms.
Asunto(s)
Glucemia/metabolismo , Dieta Alta en Grasa , Hipocampo/fisiología , Obesidad/metabolismo , Reconocimiento en Psicología/fisiología , Memoria Espacial/fisiología , Animales , Corticosterona/sangre , Femenino , Masculino , Ratas , Factores SexualesRESUMEN
Some of the prominent features of long-term memory formation include protein synthesis, gene expression, enhanced neurotransmitter release, increased excitability, and formation of new synapses. As these processes are critically dependent on mitochondrial function, we hypothesized that increased mitochondrial respiration and dynamics would play a prominent role in memory formation. To address this possibility, we measured mitochondrial oxygen consumption (OCR) in hippocampal tissue punches from trained and untrained animals. Our results show that context fear training significantly increased basal, ATP synthesis-linked, and maximal OCR in the Shaffer collateral-CA1 synaptic region, but not in the CA1 cell body layer. These changes were recapitulated in synaptosomes isolated from the hippocampi of fear-trained animals. As dynamin-related protein 1 (Drp1) plays an important role in mitochondrial fission, we examined its role in the increased mitochondrial respiration observed after fear training. Drp1 inhibitors decreased the training-associated enhancement of OCR and impaired contextual fear memory, but did not alter the number of synaptosomes containing mitochondria. Taken together, our results show context fear training increases presynaptic mitochondria respiration, and that Drp-1 mediated enhanced energy production in CA1 pre-synaptic terminals is necessary for context fear memory that does not result from an increase in the number of synaptosomes containing mitochondria or an increase in mitochondrial mass within the synaptic layer.
Asunto(s)
Consumo de Oxígeno , Sinapsis , Animales , Transporte Biológico , Trastornos de la Memoria , MitocondriasRESUMEN
Mild traumatic brain injury (mTBI) can initiate complex pathophysiological changes in the brain. Numerous cellular and molecular mechanisms underlying these pathologic changes are altered after injury, including those involved in energy utilization, excitotoxicity, ionic disturbances, and inflammation. It is thought that targeting multiple mechanisms may be necessary to produce meaningful reductions in brain pathology and to improve outcome. Previous studies have reported that the anti-diabetic drug metformin can also affect inflammatory, cell survival, and metabolic outcomes, possibly by acting on multiple targets and/or pathways. We therefore questioned whether metformin treatment can reduce pathology after repeat mild closed head injury (rmCHI) in male C57Bl/6 mice. We found that metformin, administered acutely after each head impact, resulted in markedly reduced white matter damage, astrogliosis, loss of hippocampal parvalbumin neurons, and improved mitochondrial function. In addition, both motor and cognitive functions were significantly improved when tested after discontinuation of the treatment. These studies suggest that metformin may be beneficial as a treatment for repeat concussion.
Asunto(s)
Conmoción Encefálica , Traumatismos Cerrados de la Cabeza , Metformina , Animales , Encéfalo , Conmoción Encefálica/tratamiento farmacológico , Modelos Animales de Enfermedad , Masculino , Metformina/farmacología , Ratones , Ratones Endogámicos C57BLRESUMEN
In the adult brain, self-renewing radial-glia like (RGL) progenitor cells have been shown to reside in the subventricular zone and the subgranular zone of the hippocampus. A large body of evidence shows that experiences such as learning, enriched environment and stress can alter proliferation and differentiation of RGL progenitor cells. The progenitor cells present in the subgranular zone of the hippocampus divide to give rise to newborn neurons that migrate to the dentate gyrus where they differentiate into adult granule neurons. These newborn neurons have been found to have a unique role in certain types of hippocampus-dependent learning and memory, including goal-directed behaviors that require pattern separation. Experimental traumatic brain injury (TBI) in rodents has been shown to alter hippocampal neurogenesis, including triggering the acute loss of newborn neurons, as well as progenitor cell hyper-proliferation. In this review, we discuss the role of hippocampal neurogenesis in learning and memory. Furthermore, we review evidence for the molecular mechanisms that contribute to newborn neuron loss, as well as increased progenitor cell proliferation after TBI. Finally, we discuss strategies aimed at enhancing neurogenesis after TBI and their possible therapeutic benefits.
Asunto(s)
Lesiones Traumáticas del Encéfalo , Hipocampo , Neurogénesis/fisiología , Animales , Lesiones Traumáticas del Encéfalo/patología , Lesiones Traumáticas del Encéfalo/fisiopatología , Hipocampo/patología , Hipocampo/fisiopatología , HumanosRESUMEN
Phosphatase and tensin homolog (PTEN)-induced kinase 1 (Pink1) is involved in mitochondrial quality control, which is essential for maintaining energy production and minimizing oxidative damage from dysfunctional/depolarized mitochondria. Pink1 mutations are the second most common cause of autosomal recessive Parkinson's disease (PD). In addition to characteristic motor impairments, PD patients also commonly exhibit cognitive impairments. As the hippocampus plays a prominent role in cognition, we tested if loss of Pink1 in mice influences learning and memory. While wild-type mice were able to perform a contextual discrimination task, age-matched Pink1 knockout (Pink1-/-) mice showed an impaired ability to differentiate between two similar contexts. Similarly, Pink1-/- mice performed poorly in a delayed alternation task as compared to age-matched controls. Poor performance in these cognitive tasks was not the result of overt hippocampal pathology. However, a significant reduction in hippocampal tyrosine hydroxylase (TH) protein levels was detected in the Pink1-/- mice. This decrease in hippocampal TH levels was also associated with reduced DOPA decarboxylase and dopamine D2 receptor levels, but not post-synaptic dopamine D1 receptor levels. These presynaptic changes appeared to be selective for dopaminergic fibers as hippocampal dopamine beta hydroxylase, choline acetyltransferase, and tryptophan hydroxylase levels were unchanged in Pink1-/- mice. Administration of the dopamine D1 receptor agonist SKF38393 to Pink1-/- mice was found to improve performance in the context discrimination task. Taken together, our results show that Pink1 loss may alter dopamine signaling in the hippocampus, which could be a contributing mechanism for the observed learning and memory impairments.
Asunto(s)
Hipocampo/metabolismo , Aprendizaje/fisiología , Memoria/fisiología , Proteínas Quinasas/deficiencia , Tirosina 3-Monooxigenasa/metabolismo , Animales , Dopamina/metabolismo , Antagonistas de Dopamina/farmacología , Aprendizaje/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Trastornos Parkinsonianos/metabolismo , Receptores de Dopamina D1/metabolismoRESUMEN
In the majority of cases, the cognitive and behavioral impairments resulting from a mild traumatic brain injury (TBI) (also referred to as concussion) wane within days to weeks. In contrast, these impairments can persist for months to years after repetitive mild TBI (rmTBI). The cellular and molecular mechanisms underlying these impairments are not well understood. In the present study, we examined the consequences of rmTBI (three weight drops each separated by 72 h) on brain tissue respiration, pathology, and cognitive performance in mice. The transcription factor nuclear factor-erythroid 2-realted factor 2 (Nrf2) has been demonstrated to enhance the expression of numerous cytoprotective genes. Carnosic acid (CA) has been shown to activate Nrf2 and suppress the proinflammatory transcription factor nuclear factor kappa B (NF-κB). Because contemporaneous activation of cytoprotective genes and inhibition of proinflammatory genes can be beneficial, we questioned whether CA can be used to mitigate the pathobiology of rmTBI. The rmTBI increased hippocampal adenosine triphosphate-linked tissue respiration and proton leak that were unaffected by CA treatment. The rmTBI also caused significant motor and cognitive dysfunction, as tested using the foot fault, Barnes maze, and novel object recognition tasks. These impairments occurred in the absence of visible neuronal or dendritic loss. Post-rmTBI administration of CA significantly improved motor and cognitive function, and decreased Gfap and Iba1 immunoreactivities within white matter tracks. Taken together, these results show that rmTBI can cause cognitive impairments in the absence of overt neuronal pathologies, and post-injury treatment with CA can lessen some of these impairments.
Asunto(s)
Abietanos/farmacología , Antioxidantes/farmacología , Conmoción Encefálica , Recuperación de la Función/efectos de los fármacos , Animales , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
Ellagic acid is a botanical polyphenol which has been shown to have numerous effects on cellular function. Ellagic acid can induce apoptosis and inhibit the proliferation of various cancer cell types in vitro and in vivo. As such, ellagic acid has attracted significant interest as a potential chemotherapeutic compound. One mechanism by which ellagic acid has been proposed to affect cellular physiology is by regulating metabolic pathways. Here we show the dose-dependent effects of ellagic acid on cellular energy production and downstream induction of the apoptotic program in HEK293, HeLa, MCF7, and HepG2 cells. At physiologically relevant doses, ellagic acid has pleiotropic and cell-type specific effects on mitochondrial function. At high doses ellagic acid can also influence glycolytic pathways and induce cell death. Our results demonstrate that ellagic acid can influence mitochondrial function at therapeutically relevant concentrations. The observed effects of ellagic acid on cellular respiration are complex and cell type-specific, which may limit the chemotherapeutic utility of this compound.
Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Ácido Elágico/farmacología , Metabolismo Energético/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Adenosina Trifosfato/metabolismo , Apoptosis/efectos de los fármacos , Caspasa 3/metabolismo , Caspasa 6/metabolismo , Relación Dosis-Respuesta a Droga , Células HEK293 , Células HeLa , Células Hep G2 , Humanos , Células MCF-7 , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Mitocondrias/metabolismo , Mitocondrias/patología , Neoplasias/metabolismo , Neoplasias/patología , Factores de TiempoRESUMEN
BACKGROUND: High-fat diets promoting obesity/type-2 diabetes can impair physiology and cognitive performance, although sex-dependent comparisons of these impairments are rarely made. Transient reductions in Ca(2+)-dependent afterhyperpolarizations (AHPs) occur during memory consolidation, enhancing intrinsic excitability of hippocampal CA1 pyramidal neurons. In rats fed standard diets, insulin can enhance memory and reduce amplitude and duration of AHPs. METHODS: Effects of chronic high-fat diet (HFD) on memory, circulating insulin, and neuronal physiology were compared between young adult male and female Long-Evans rats. Rats fed for 12 weeks (from weaning) a HFD or a control diet (CD) were then tested in vivo prior to in vitro recordings from CA1 pyramidal neurons. RESULTS: The HFD significantly impaired spatial memory in both males and females. Significant sex differences occurred in circulating insulin and in the insulin sensitivity of hippocampal neurons. Circulating insulin significantly increased in HFD males but decreased in HFD females. While the HFD significantly reduced hippocampal intrinsic excitability in both sexes, CA1 neurons from HFD females remained insulin-sensitive but those from HFD males became insulin-insensitive. CONCLUSIONS: Findings consistent with these have been characterized previously in HFD or senescent males, but the effects observed here in young females are unique. Loss of CA1 neuronal excitability, and sex-dependent loss of insulin sensitivity, can have significant cognitive consequences, over both the short term and the life span. These findings highlight needs for more research into sex-dependent differences, relating systemic and neural plasticity mechanisms in metabolic disorders.