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ABSTRACT: The transcription factor cAMP response element binding protein (CREB) is a key protein implicated in memory, synaptic plasticity and structural plasticity in mammals. Whether CREB regulates the synaptic incorporation of hippocampal glutamatergic receptors under basal and learning-induced conditions remains, however, mostly unknown. Using double-transgenic mice conditionally expressing a dominant negative form of CREB (CREBS133A, mCREB), we analyzed how chronic loss of CREB function in adult hippocampal glutamatergic neurons impacts the levels of the AMPA and NMDA receptors subunits within the post-synaptic densities (PSD). In basal (naïve) conditions, we report that inhibition of CREB function was associated with a specific reduction of the AMPAR subunit GluA1 and a proportional increase in its Ser845 phosphorylated form within the PSD. These molecular alterations correlated with a reduction in AMPA receptors mEPSC frequency, with a decrease in long-term potentiation (LTP), and with an increase in long-term depression (LTD). The basal levels other major synaptic proteins (GluA2/3, GluN1, GluN2A, and PSD95) within the PSD were not affected by CREB inhibition. Blocking CREB function also impaired contextual fear conditioning (CFC) and selectively blocked the CFC-driven enhancement of GluA1 and its Ser845 phosphorylated form within the PSD, molecular changes normally observed in wild-type mice. CFC-driven enhancement of other synaptic proteins (GluA2/3, GluN1, GluN2A, and PSD95) within the PSD was not significantly perturbed by the loss of CREB function. These findings provide the first evidence that, in vivo, CREB is necessary for the specific maintenance of the GluA1 subunit within the PSD of hippocampal neurons in basal conditions and for its trafficking within the PSD during the occurrence of learning. © 2013 Wiley Periodicals, Inc.
Hippocampus 03/2013; · 5.18 Impact Factor
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ABSTRACT: Neuronal transmission and functional synapses require mitochondria, which are mainly involved in the generation of energy (ATP and NAD+), regulation of cell signalling and calcium homeostasis. Particularly intriguing is emerging data suggesting the relationship between mitochondria and neurotrophic factors that can act at the synaptic level promoting neuronal transmission and plasticity. On the other hand, disturbances in mitochondrial functions might contribute to impaired synaptic transmission and neuronal degeneration in Alzheimer's Disease and other chronic and acute neurodegenerative disorders. Here, we review the molecular mediators controlling mitochondrial function and their impact on synaptic dysfunction associated with the pathogenesis of Alzheimer's Disease.
Current pharmaceutical design 02/2013; · 4.41 Impact Factor
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ABSTRACT: Caspase-3 has been identified as a key mediator of neuronal programmed cell death. This protease plays a central role in the developing nervous system and its activation is observed early in neural tube formation and persists during postnatal differentiation of the neural network. Caspase-3 activation, a crucial event of neuronal cell death program, is also a feature of many chronic neurodegenerative diseases. This traditional apoptotic function of caspase-3 is challenged by recent studies that reveal new cell death-independent roles for mitochondrial-activated caspase-3 in neurite pruning and synaptic plasticity. These findings underscore the need for further research into the mechanism of action and functions of caspase-3 that may prove useful in the development of novel pharmacological treatments for a diverse range of neurological disorders.
Trends in Neurosciences 07/2012; 35(11):700-9. · 14.23 Impact Factor
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ABSTRACT: The human brain contains about 100 billion neurons forming an intricate network of innumerable connections, which continuously adapt and rewire themselves following inputs from external and internal environments as well as the physiological synaptic, dendritic and axonal sculpture during brain maturation and throughout the life span. Growing evidence supports the idea that Alzheimer's disease (AD) targets selected and functionally connected neuronal networks and, specifically, their synaptic terminals, affecting brain connectivity well before producing neuronal loss and compartmental atrophy. The understanding of the molecular mechanisms underlying the dismantling of neuronal circuits and the implementation of 'clinically oriented' methods to map-out the dynamic interactions amongst neuronal assemblies will enhance early/pre-symptomatic diagnosis and monitoring of disease progression. More important, this will open the avenues to innovative treatments, bridging the gap between molecular mechanisms and the variety of symptoms forming disease phenotype. In the present review a set of evidence supports the idea that altered brain connectivity, exhausted neural plasticity and aberrant neuronal activity are facets of the same coin linked to age-related neurodegenerative dementia of Alzheimer type. Investigating their respective roles in AD pathophysiology will help in translating findings from basic research to clinical applications.
Progress in Neurobiology 07/2012; 99(1):42-60. · 8.87 Impact Factor
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ABSTRACT: The mature brain is a highly dynamic organ that constantly changes its organization by destroying and forming new connections. Collectively, these changes are referred to as brain plasticity and are associated with functional changes, such as memory, addiction, and recovery of function after brain damage. Neuronal plasticity is sustained by the fine regulation of protein synthesis and organelle biogenesis and their degradation to ensure efficient turnover. Thus, autophagy, as quality control mechanism of proteins and organelles in neurons, is essential to their physiology and pathology. Here, we review recent several findings proving that defects in autophagy affect neuronal function and impair functional recovery after brain insults, contributing to neurodegeneration, in chronic and acute neurological disorders. Thus, an understanding of the molecular mechanisms by which the autophagy machinery is finely regulated might accelerate the development of therapeutic interventions in many neurological disorders for which no cure is available.
Molecular Neurobiology 07/2012; 46(2):513-21. · 5.74 Impact Factor
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Robert Nisticò,
Virve Cavallucci,
Sonia Piccinin,
Simone Macrì,
Marco Pignatelli,
Bisan Mehdawy,
Fabio Blandini,
Giovanni Laviola,
Davide Lauro,
Nicola B Mercuri, Marcello D'Amelio
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ABSTRACT: The insulin receptor (IR) is a protein tyrosine kinase playing a pivotal role in the regulation of peripheral glucose metabolism and energy homoeostasis. IRs are also abundantly distributed in the cerebral cortex and hippocampus, where they regulate synaptic activity required for learning and memory. As the major anabolic hormone in mammals, insulin stimulates protein synthesis partially through the activation of the PI3K/Akt/mTOR pathway, playing fundamental roles in neuronal development, synaptic plasticity and memory. Here, by means of a multidisciplinary approach, we report that long-term synaptic plasticity and recognition memory are impaired in IR β-subunit heterozygous mice. Since IR expression is diminished in type-2 diabetes as well as in Alzheimer's disease (AD) patients, these data may provide a mechanistic link between insulin resistance, impaired synaptic transmission and cognitive decline in humans with metabolic disorders.
Neuromolecular medicine 06/2012; · 5.00 Impact Factor
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ABSTRACT: Alzheimer's Disease (AD), the most common age-related neurodegenerative disorder, is characterized by progressive cognitive decline, synaptic loss, the formation of extracellular β-amyloid plaques and intracellular neurofibrillary tangles, and neuronal cell death. Despite the massive neuronal loss in the 'late stage' of disease, dendritic spine loss represents the best pathological correlate to the cognitive impairment in AD patients. The 'amyloid hypothesis' of AD recognizes the Aβ peptide as the principal player in the pathological process. Many lines of evidence point out to the neurotoxicity of Aβ, highlighting the correlation between soluble Aβ oligomer accumulation, rather than insoluble Aβ fibrils and disease progression. Pathological increase of Aβ in AD brains, resulting from an imbalance between its production, aggregation and clearance, might target mitochondrial function promoting a progressive synaptic impairment. The knowledge of the exact mechanisms by which Aβ peptide impairs neuronal function will help us to design new pharmacological tools for preventing AD neurodegeneration.
Molecular Neurobiology 03/2012; 45(2):366-78. · 5.74 Impact Factor
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Maria Teresa Viscomi, Marcello D'Amelio,
Virve Cavallucci,
Laura Latini,
Elisa Bisicchia,
Francesca Nazio,
Francesca Fanelli,
Mauro Maccarrone,
Sandra Moreno,
Francesco Cecconi,
Marco Molinari
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ABSTRACT: Autophagy is the evolutionarily conserved degradation and recycling of cellular constituents. In mammals, autophagy is implicated in the pathogenesis of many neurodegenerative diseases. However, its involvement in acute brain damage is unknown. This study addresses the function of autophagy in neurodegeneration that has been induced by acute focal cerebellar lesions. We provide morphological, ultrastructural, and biochemical evidence that lesions in a cerebellar hemisphere activate autophagy in axotomized precerebellar neurons. Through time course analyses of the apoptotic cascade, we determined mitochondrial dysfunction to be the early trigger of degeneration. Further, the stimulation of autophagy by rapamycin and the employment of mice with impaired autophagic responses allowed us to demonstrate that autophagy protects from damage promoting functional recovery. These findings have therapeutic significance, demonstrating the potential of pro-autophagy treatments for acute brain pathologies, such as stroke and brain trauma.
Autophagy 02/2012; 8(2):222-35. · 7.45 Impact Factor
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ABSTRACT: Neurodegenerative diseases that include amyotrophic lateral sclerosis, Huntington's disease, Alzheimer's disease, Parkinson's disease, stroke, brain trauma and spinal cord injury, are associated with the inappropriate activation of a neuronal cell-suicide program called apoptosis. Given that central nervous system tissue has very limited regenerative capacity it is of extreme importance to limit the damage caused by neuronal death. During the past decade, considerable progress has been made in understanding the process of apoptosis and, significantly, a number of studies have shown that a variety of small molecules can activate or inhibit cell death by acting on crucial checkpoints of apoptosis. Here, we review evidence linking apoptosis to brain diseases and discuss how knowledge of the mechanisms of cell death has led to novel therapeutic strategies.
Current pharmaceutical design 02/2011; 17(3):215-29. · 4.41 Impact Factor
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Marcello D'Amelio,
Virve Cavallucci,
Silvia Middei,
Cristina Marchetti,
Simone Pacioni,
Alberto Ferri,
Adamo Diamantini,
Daniela De Zio,
Paolo Carrara,
Luca Battistini,
Sandra Moreno,
Alberto Bacci,
Martine Ammassari-Teule,
Hélène Marie,
Francesco Cecconi
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ABSTRACT: Synaptic loss is the best pathological correlate of the cognitive decline in Alzheimer's disease; however, the molecular mechanisms underlying synaptic failure are unknown. We found a non-apoptotic baseline caspase-3 activity in hippocampal dendritic spines and an enhancement of this activity at the onset of memory decline in the Tg2576-APPswe mouse model of Alzheimer's disease. In spines, caspase-3 activated calcineurin, which in turn triggered dephosphorylation and removal of the GluR1 subunit of AMPA-type receptor from postsynaptic sites. These molecular modifications led to alterations of glutamatergic synaptic transmission and plasticity and correlated with spine degeneration and a deficit in hippocampal-dependent memory. Notably, pharmacological inhibition of caspase-3 activity in Tg2576 mice rescued the observed Alzheimer-like phenotypes. Our results identify a previously unknown caspase-3-dependent mechanism that drives synaptic failure and contributes to cognitive dysfunction in Alzheimer's disease. These findings indicate that caspase-3 is a potential target for pharmacological therapy during early disease stages.
Nature Neuroscience 01/2011; 14(1):69-76. · 15.53 Impact Factor
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Sabrina Di Bartolomeo,
Marco Corazzari,
Francesca Nazio,
Serafina Oliverio,
Gaia Lisi,
Manuela Antonioli,
Vittoria Pagliarini,
Silvia Matteoni,
Claudia Fuoco,
Luigi Giunta, Marcello D'Amelio,
Roberta Nardacci,
Alessandra Romagnoli,
Mauro Piacentini,
Francesco Cecconi,
Gian Maria Fimia
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ABSTRACT: Autophagy is an evolutionary conserved catabolic process involved in several physiological and pathological processes such as cancer and neurodegeneration. Autophagy initiation signaling requires both the ULK1 kinase and the BECLIN 1-VPS34 core complex to generate autophagosomes, double-membraned vesicles that transfer cellular contents to lysosomes. In this study, we show that the BECLIN 1-VPS34 complex is tethered to the cytoskeleton through an interaction between the BECLIN 1-interacting protein AMBRA1 and dynein light chains 1/2. When autophagy is induced, ULK1 phosphorylates AMBRA1, releasing the autophagy core complex from dynein. Its subsequent relocalization to the endoplasmic reticulum enables autophagosome nucleation. Therefore, AMBRA1 constitutes a direct regulatory link between ULK1 and BECLIN 1-VPS34, which is required for core complex positioning and activity within the cell. Moreover, our results demonstrate that in addition to a function for microtubules in mediating autophagosome transport, there is a strict and regulatory relationship between cytoskeleton dynamics and autophagosome formation.
The Journal of Cell Biology 10/2010; 191(1):155-68. · 10.26 Impact Factor
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AnnaMaria Cimini,
Sandra Moreno, Marcello D'Amelio,
Loredana Cristiano,
Barbara D'Angelo,
Stefano Falone,
Elisabetta Benedetti,
Paolo Carrara,
Francesca Fanelli,
Francesco Cecconi,
Fernanda Amicarelli,
Maria Paola Cerù
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ABSTRACT: The central role of peroxisomes in reactive oxygen species and lipid metabolism and their importance in brain functioning are well established. The aim of this work has been to study the peroxisomal population in the Tg2576 mouse model of Alzheimer's disease (AD), at the age of three months when no apparent signs of behavioral, neuroanatomical, cytological, or biochemical alterations have been so far described. The expression and localization of peroxisomal (PMP70, CAT, AOX, and THL) and peroxisome-related proteins (PEX5p, GPX1, SOD1, and SOD2) were studied in the neocortex and hippocampus of transgenic and wild-type animals. Oxidative stress markers (TBARS, acrolein, and 8-OHG) were also evaluated. Our results demonstrate that significant alterations are already detectable at this early stage of the disease and also involve peroxisomes. Their number and protein composition change concomitantly with early oxidative stress. Interestingly, the neocortex shows a compensatory response, consisting in an increase of reactive oxygen species scavenging enzymes, while the hippocampus appears more prone to the oxidative insult. This different behavior could be related to metabolic differences in the two brain areas, also involving peroxisome abundance and/or enzymatic content.
Journal of Alzheimer's disease: JAD 09/2009; 18(4):935-52. · 3.74 Impact Factor
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Filippo Biamonte,
Giovanni Assenza,
Ramona Marino, Marcello D'Amelio,
Roger Panteri,
Donatella Caruso,
Samuele Scurati,
Josue Garcia Yague,
Luis Miguel Garcia-Segura,
Roberta Cesa,
Piergiorgio Strata,
Roberto Cosimo Melcangi,
Flavio Keller
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ABSTRACT: We determined total Purkinje cell (PC) numbers in cerebella of wild-type (+/+) and heterozygous (rl/+) reeler mice of either sex during early postnatal development; in parallel, we quantified levels of neuroactive steroids in the cerebellum with mass spectrometry. We also quantified reelin mRNA and protein expression with RT-PCR and Western blotting. PC numbers are selectively reduced at postnatal day 15 (P15) in rl/+ males in comparison to +/+ males, +/+ females, and rl/+ females. Administration of 17beta-estradiol (17beta-E) into the cisterna magna at P5 increases PC numbers in rl/+ males, but not in the other groups; conversely, estrogen antagonists 4-OH-tamoxifen or ICI 182,780 reduce PC numbers in +/+ and rl/+ females, but have no effect in males. Testosterone (T) levels at P5 are much higher in males than in females, reflecting the perinatal testosterone surge in males. In addition, rl/+ male cerebella at P5 show a peculiar hormonal profile in comparison with the other groups, consisting of increased levels of T and 17beta-E, and decreased levels of dihydrotestosterone. RT-PCR analysis indicated that heterozygosity leads to a 50% reduction of reelin mRNA in the cerebellum in both sexes, as expected, and that 17beta-E upregulates reelin mRNA, particularly in rl/+ males; reelin mRNA upregulation is associated with an increase of all major reelin isoforms. These effects may represent a novel model of how reelin deficiency interacts with variable perinatal levels of neuroactive steroids, leading to gender-dependent differences in genetic vulnerability.
Neurobiology of Disease 08/2009; 36(1):103-15. · 5.40 Impact Factor
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Cell cycle (Georgetown, Tex.) 06/2009; 8(10):1467. · 5.36 Impact Factor
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Diego Centonze,
Luca Muzio,
Silvia Rossi,
Francesca Cavasinni,
Valentina De Chiara,
Alessandra Bergami,
Alessandra Musella, Marcello D'Amelio,
Virve Cavallucci,
Alessandro Martorana,
Andrea Bergamaschi,
Maria Teresa Cencioni,
Adamo Diamantini,
Erica Butti,
Giancarlo Comi,
Giorgio Bernardi,
Francesco Cecconi,
Luca Battistini,
Roberto Furlan,
Gianvito Martino
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ABSTRACT: Neurodegeneration is the irremediable pathological event occurring during chronic inflammatory diseases of the CNS. Here we show that, in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, inflammation is capable in enhancing glutamate transmission in the striatum and in promoting synaptic degeneration and dendritic spine loss. These alterations occur early in the disease course, are independent of demyelination, and are strongly associated with massive release of tumor necrosis factor-alpha from activated microglia. CNS invasion by myelin-specific blood-borne immune cells is the triggering event, and the downregulation of the early gene Arc/Arg3.1, leading to the abnormal expression and phosphorylation of AMPA receptors, represents a culminating step in this cascade of neurodegenerative events. Accordingly, EAE-induced synaptopathy subsided during pharmacological blockade of AMPA receptors. Our data establish a link between neuroinflammation and synaptic degeneration and calls for early neuroprotective therapies in chronic inflammatory diseases of the CNS.
Journal of Neuroscience 04/2009; 29(11):3442-52. · 7.11 Impact Factor
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ABSTRACT: Genotoxic stress can induce autophagy in a p53-dependent fashion and p53 can transactivate autophagy-inducing genes. We have observed recently that inactivation of p53 by deletion, depletion or inhibition can trigger autophagy. Thus, human and mouse cells subjected to knockout, knockdown or pharmacological inhibition of p53 manifest signs of autophagy such as depletion of p62/SQSTM1, LC3 lipidation, redistribution of GFP-LC3 in cytoplasmic puncta, and accumulation of autophagosomes and autolysosomes, both in vitro and in vivo. Inhibition of p53 causes autophagy in enucleated cells, indicating that the cytoplasmic, non-nuclear pool of p53 can regulate autophagy. Accordingly, retransfection of p53(-/-) cells with wild-type p53 as well as a p53 mutant that is excluded from the nucleus (due to the deletion of the nuclear localization sequence) can inhibit autophagy, whereas retransfection with a nucleus-restricted p53 mutant (in which the nuclear localization sequence has been deleted) does not inhibit autophagy. Several distinct autophagy inducers (e.g., starvation, rapamycin, lithium, tunicamycin and thapsigargin) stimulate the rapid degradation of p53. In these conditions, inhibition of the p53-specific E3 ubiquitin ligase HDM2 can avoid p53 depletion and simultaneously prevent the activation of autophagy. Moreover, a p53 mutant that lacks the HDM2 ubiquitinylation site and hence is more stable than wild-type p53 is particularly efficient in suppressing autophagy. In conclusion, p53 plays a dual role in the control of autophagy. On the one hand, nuclear p53 can induce autophagy through transcriptional effects. On the other hand, cytoplasmic p53 may act as a master repressor of autophagy.
Autophagy 07/2008; 4(6):810-4. · 7.45 Impact Factor
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Ezgi Tasdemir,
M Chiara Maiuri,
Lorenzo Galluzzi,
Ilio Vitale,
Mojgan Djavaheri-Mergny, Marcello D'Amelio,
Alfredo Criollo,
Eugenia Morselli,
Changlian Zhu,
Francis Harper, [......],
Frank Madeo,
Patrizia Paterlini-Brechot,
Rosario Rizzuto,
Gyorgy Szabadkai,
Gérard Pierron,
Klas Blomgren,
Nektarios Tavernarakis,
Patrice Codogno,
Francesco Cecconi,
Guido Kroemer
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ABSTRACT: Multiple cellular stressors, including activation of the tumour suppressor p53, can stimulate autophagy. Here we show that deletion, depletion or inhibition of p53 can induce autophagy in human, mouse and nematode cells subjected to knockout, knockdown or pharmacological inhibition of p53. Enhanced autophagy improved the survival of p53-deficient cancer cells under conditions of hypoxia and nutrient depletion, allowing them to maintain high ATP levels. Inhibition of p53 led to autophagy in enucleated cells, and cytoplasmic, not nuclear, p53 was able to repress the enhanced autophagy of p53(-/-) cells. Many different inducers of autophagy (for example, starvation, rapamycin and toxins affecting the endoplasmic reticulum) stimulated proteasome-mediated degradation of p53 through a pathway relying on the E3 ubiquitin ligase HDM2. Inhibition of p53 degradation prevented the activation of autophagy in several cell lines, in response to several distinct stimuli. These results provide evidence of a key signalling pathway that links autophagy to the cancer-associated dysregulation of p53.
Nature Cell Biology 07/2008; 10(6):676-87. · 19.49 Impact Factor
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ABSTRACT: Apoptosis, often defined as programmed cell death, plays a very important role in many physiologic and pathologic conditions. Therefore, detecting apoptotic cells or monitoring the cells progressing to apoptosis is an essential step in basic and/or applied research. Apoptosis is characterized by many biologic and morphologic changes of cells, for example, cytochrome c release from mitochondria, activation of caspases, DNA fragmentation, membrane blebbing, and formation of apoptotic bodies. On the basis of these changes, various assays have been designed to detect or quantify apoptotic cells. The goal of this chapter is to provide readers with a scientific guide to proven methods that highlight the current strategies for detecting apoptosis in the nervous system.
Methods in Enzymology 02/2008; 446:259-76. · 2.04 Impact Factor
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Yael Zermati,
Shahul Mouhamad,
Lilli Stergiou,
Benjamin Besse,
Lorenzo Galluzzi,
Simone Boehrer,
Anne-Laure Pauleau,
Filippo Rosselli, Marcello D'Amelio,
Roberto Amendola,
Maria Castedo,
Michael Hengartner,
Jean-Charles Soria,
Francesco Cecconi,
Guido Kroemer
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ABSTRACT: Apaf-1 is an essential factor for cytochrome c-driven caspase activation during mitochondrial apoptosis but has also an apoptosis-unrelated function. Knockdown of Apaf-1 in human cells, knockout of apaf-1 in mice, and loss-of-function mutations in the Caenorhabditis elegans apaf-1 homolog ced-4 reveal the implication of Apaf-1/CED-4 in DNA damage-induced cell-cycle arrest. Apaf-1 loss compromised the DNA damage checkpoints elicited by ionizing irradiation or chemotherapy. Apaf-1 depletion reduced the activation of the checkpoint kinase Chk1 provoked by DNA damage, and knockdown of Chk1 abrogated the Apaf-1-mediated cell-cycle arrest. Nuclear translocation of Apaf-1, induced in vitro by exogenous DNA-damaging agents, correlated in non-small cell lung cancer (NSCLC) with the endogenous activation of Chk-1, suggesting that this pathway is clinically relevant. Hence, Apaf-1 exerts two distinct, phylogenetically conserved roles in response to mitochondrial membrane permeabilization and DNA damage. These data point to a role for Apaf-1 as a bona fide tumor suppressor.
Molecular Cell 12/2007; 28(4):624-37. · 14.18 Impact Factor
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ABSTRACT: During development, Pax6 is expressed in a rostrolateral-high to caudomedial-low gradient in the majority of the cortical radial glial progenitors and endows them with neurogenic properties. Using a Cre/loxP-based approach, we studied the effect of conditional activation of two Pax6 isoforms, Pax6 and Pax6-5a, on the corticogenesis of transgenic mice. We found that activation of either Pax6 or Pax6-5a inhibits progenitor proliferation in the developing cortex. Upon activation of transgenic Pax6, specific progenitor pools with distinct endogenous Pax6 expression levels at different developmental stages show defects in cell cycle progression and in the acquisition of apoptotic or neuronal cell fate. The results provide new evidence for the complex role of Pax6 in mammalian corticogenesis.
Development 05/2007; 134(7):1311-22. · 6.60 Impact Factor
