Author
Frank W. Pfrieger
Other affiliations: Stanford University, University of Strasbourg, Max Planck Society ...read more
Bio: Frank W. Pfrieger is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Neuroglia & Synaptogenesis. The author has an hindex of 36, co-authored 73 publications receiving 8307 citations. Previous affiliations of Frank W. Pfrieger include Stanford University & University of Strasbourg.
Topics: Neuroglia, Synaptogenesis, Synapse, Astrocyte, Retinal ganglion
Papers published on a yearly basis
Papers
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TL;DR: Cholesterol complexed to apolipoprotein E-containing lipoproteins may explain the delayed onset of CNS synaptogenesis after glia differentiation and neurobehavioral manifestations of defects in cholesterol or lipoprotein homeostasis.
Abstract: The molecular mechanisms controlling synaptogenesis in the central nervous system (CNS) are poorly understood. Previous reports showed that a glia-derived factor strongly promotes synapse development in cultures of purified CNS neurons. Here, we identify this factor as cholesterol complexed to apolipoprotein E-containing lipoproteins. CNS neurons produce enough cholesterol to survive and grow, but the formation of numerous mature synapses demands additional amounts that must be provided by glia. Thus, the availability of cholesterol appears to limit synapse development. This may explain the delayed onset of CNS synaptogenesis after glia differentiation and neurobehavioral manifestations of defects in cholesterol or lipoprotein homeostasis.
1,543 citations
TL;DR: It is suggested that neurotransmitter stimulation and electrical activity enhance the survival of developing RGCs and raise the question of whether the survival control mechanisms of PNS and CNS neurons are different.
840 citations
Université Paris-Saclay1, Autonomous University of Barcelona2, University of Cambridge3, National Institute for Occupational Safety and Health4, University of Bonn5, German Center for Neurodegenerative Diseases6, Harvard University7, University of Lausanne8, National Research Council9, University of Padua10, Heidelberg University11, Salk Institute for Biological Studies12, University of Minnesota13, Pasteur Institute14, Tel Aviv University15, Johns Hopkins University16, University of Portsmouth17, Katholieke Universiteit Leuven18, PSL Research University19, Trinity College, Dublin20, Baylor College of Medicine21, University College London22, University of Edinburgh23, Oregon Health & Science University24, National Institutes of Health25, Columbia University26, University of Rochester27, University of Copenhagen28, Ludwig Maximilian University of Munich29, University of Málaga30, Tufts University31, University of Freiburg32, Utrecht University33, Nihon University34, Max Delbrück Center for Molecular Medicine35, University of California, Los Angeles36, University of Yamanashi37, New York University38, University of British Columbia39, King Abdullah University of Science and Technology40, University of Wisconsin-Madison41, University of California, San Francisco42, McGill University43, University of Kentucky44, Kyushu University45, University of Bordeaux46, Polytechnic Institute of Cávado and Ave47, University of Minho48, University of Alabama at Birmingham49, University of Gothenburg50, University of Poitiers51, Cajal Institute52, King's College London53, University of Strasbourg54, Virginia Tech55, University of Düsseldorf56, I.M. Sechenov First Moscow State Medical University57, Russian Academy of Sciences58, University of Seville59, Georgia Institute of Technology60, University of Texas Health Science Center at Houston61, University of California, San Diego62, Universidade Federal do Rio Grande do Sul63, University of Ljubljana64, Ikerbasque65, University of Manchester66
TL;DR: In this article, the authors point out the shortcomings of binary divisions of reactive astrocytes into good-vs-bad, neurotoxic vs-neuroprotective or A1-vs.A2.
Abstract: Reactive astrocytes are astrocytes undergoing morphological, molecular, and functional remodeling in response to injury, disease, or infection of the CNS. Although this remodeling was first described over a century ago, uncertainties and controversies remain regarding the contribution of reactive astrocytes to CNS diseases, repair, and aging. It is also unclear whether fixed categories of reactive astrocytes exist and, if so, how to identify them. We point out the shortcomings of binary divisions of reactive astrocytes into good-vs-bad, neurotoxic-vs-neuroprotective or A1-vs-A2. We advocate, instead, that research on reactive astrocytes include assessment of multiple molecular and functional parameters-preferably in vivo-plus multivariate statistics and determination of impact on pathological hallmarks in relevant models. These guidelines may spur the discovery of astrocyte-based biomarkers as well as astrocyte-targeting therapies that abrogate detrimental actions of reactive astrocytes, potentiate their neuro- and glioprotective actions, and restore or augment their homeostatic, modulatory, and defensive functions.
797 citations
TL;DR: Developing neurons in culture form inefficient synapses that require glial signals to become fully functional, and the role of glial cells in synapse formation and function was studied in cultures of purified neurons from the rat central nervous system.
Abstract: In the developing nervous system, glial cells guide axons to their target areas, but it is unknown whether they help neurons to establish functional synaptic connections. The role of glial cells in synapse formation and function was studied in cultures of purified neurons from the rat central nervous system. In glia-free cultures, retinal ganglion cells formed synapses with normal ultrastructure but displayed little spontaneous synaptic activity and high failure rates in evoked synaptic transmission. In cocultures with neuroglia, the frequency and amplitude of spontaneous postsynaptic currents were potentiated by 70-fold and 5-fold, respectively, and fewer transmission failures occurred. Glial cells increased the action potential-independent quantal release by 12-fold without affecting neuronal survival. Thus, developing neurons in culture form inefficient synapses that require glial signals to become fully functional.
771 citations
TL;DR: An integrated view of how several distinct cell types contribute in complementary ways to cell maintenance and the reaction to injury is provided.
542 citations
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TL;DR: It is shown that growth factor activation of the PI3'K/Akt signaling pathway culminates in the phosphorylation of the BCL-2 family member BAD, thereby suppressing apoptosis and promoting cell survival.
5,831 citations
TL;DR: The mechanisms by which survival factors regulate the PI3K/c-Akt cascade, the evidence that activation of the PI 3K/ c-AKT pathway promotes cell survival, and the current spectrum of c- akt targets and their roles in mediating c- Akt-dependent cell survival are reviewed.
Abstract: The programmed cell death that occurs as part of normal mammalian development was first observed nearly a century ago (Collin 1906). It has since been established that approximately half of all neurons in the neuroaxis and >99.9% of the total number of cells generated during the course of a human lifetime go on to die through a process of apoptosis (for review, see Datta and Greenberg 1998; Vaux and Korsmeyer 1999). The induction of developmental cell death is a highly regulated process and can be suppressed by a variety of extracellular stimuli. The purification in the 1950s of the nerve growth factor (NGF), which promotes the survival of sympathetic neurons, set the stage for the discovery that peptide trophic factors promote the survival of a wide variety of cell types in vitro and in vivo (Levi-Montalcini 1987). The profound biological consequences of growth factor (GF) suppression of apoptosis are exemplified by the critical role of target-derived neurotrophins in the survival of neurons and the maintenance of functional neuronal circuits. (Pettmann and Henderson 1998). Recently, the ability of trophic factors to promote survival have been attributed, at least in part, to the phosphatidylinositide 38-OH kinase (PI3K)/c-Akt kinase cascade. Several targets of the PI3K/c-Akt signaling pathway have been recently identified that may underlie the ability of this regulatory cascade to promote survival. These substrates include two components of the intrinsic cell death machinery, BAD and caspase 9, transcription factors of the forkhead family, and a kinase, IKK, that regulates the NF-kB transcription factor. This article reviews the mechanisms by which survival factors regulate the PI3K/c-Akt cascade, the evidence that activation of the PI3K/c-Akt pathway promotes cell survival, and the current spectrum of c-Akt targets and their roles in mediating c-Akt-dependent cell survival.
4,260 citations
TL;DR: It is shown that C1q, the initiating protein in the classical complement cascade, is expressed by postnatal neurons in response to immature astrocytes and is localized to synapses throughout the postnatal CNS and retina, supporting a model in which unwanted synapses are tagged by complement for elimination and suggesting that complement-mediated synapse elimination may become aberrantly reactivated in neurodegenerative disease.
2,501 citations
TL;DR: The A β-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk are discussed, and how to design effective strategies for AD therapy by targeting ApO-E is considered.
Abstract: Apolipoprotein E (Apo-E) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the e4 allele are at increased risk of AD compared with those carrying the more common e3 allele, whereas the e2 allele decreases risk. Presence of the APOE e4 allele is also associated with increased risk of cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. Apo-E-lipoproteins bind to several cell-surface receptors to deliver lipids, and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. Apo-E isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on Apo-E in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different Apo-E isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting Apo-E.
2,463 citations
TL;DR: Major advances in understanding of adult mammalian neurogenesis in the dentate gyrus of the hippocampus and from the subventricular zone of the lateral ventricle, the rostral migratory stream to the olfactory bulb are reviewed.
2,308 citations