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Balena T, Lillis K, Rahmati N, Bahari F, Dzhala V, Berdichevsky E, Staley K. A Dynamic Balance between Neuronal Death and Clearance in an in Vitro Model of Acute Brain Injury. J Neurosci 2023; 43:6084-6107. [PMID: 37527922 PMCID: PMC10451151 DOI: 10.1523/jneurosci.0436-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/15/2023] [Accepted: 07/20/2023] [Indexed: 08/03/2023] Open
Abstract
In in vitro models of acute brain injury, neuronal death may overwhelm the capacity for microglial phagocytosis, creating a queue of dying neurons awaiting clearance. Neurons undergoing programmed cell death are in this queue, and are the most visible and frequently quantified measure of neuronal death after injury. However, the size of this queue should be equally sensitive to changes in neuronal death and the rate of phagocytosis. Using rodent organotypic hippocampal slice cultures as a model of acute perinatal brain injury, serial imaging demonstrated that the capacity for microglial phagocytosis of dying neurons was overwhelmed for 2 weeks. Altering phagocytosis rates (e.g., by changing the number of microglia) dramatically changed the number of visibly dying neurons. Similar effects were generated when the visibility of dying neurons was altered by changing the membrane permeability for stains that label dying neurons. Canonically neuroprotective interventions, such as seizure blockade, and neurotoxic maneuvers, such as perinatal ethanol exposure, were mediated by effects on microglial activity and the membrane permeability of neurons undergoing programmed cell death. These canonically neuroprotective and neurotoxic interventions had either no or opposing effects on healthy surviving neurons identified by the ongoing expression of transgenic fluorescent proteins.SIGNIFICANCE STATEMENT In in vitro models of acute brain injury, microglial phagocytosis is overwhelmed by the number of dying cells. Under these conditions, the assumptions on which assays for neuroprotective and neurotoxic effects are based are no longer valid. Thus, longitudinal assays of healthy cells, such as serial assessment of the fluorescence emission of transgenically expressed proteins, provide more accurate estimates of cell death than do single-time point anatomic or biochemical assays of the number of dying neurons. More accurate estimates of death rates in vitro will increase the translatability of preclinical studies of neuroprotection and neurotoxicity.
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Affiliation(s)
- Trevor Balena
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kyle Lillis
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Negah Rahmati
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Fatemeh Bahari
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Volodymyr Dzhala
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Eugene Berdichevsky
- Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Kevin Staley
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
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Balena T, Lillis K, Rahmati N, Bahari F, Dzhala V, Berdichevsky E, Staley K. A dynamic balance between neuronal death and clearance after acute brain injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.14.528332. [PMID: 36824708 PMCID: PMC9948967 DOI: 10.1101/2023.02.14.528332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
After acute brain injury, neuronal apoptosis may overwhelm the capacity for microglial phagocytosis, creating a queue of dying neurons awaiting clearance. The size of this queue should be equally sensitive to changes in neuronal death and the rate of phagocytosis. Using rodent organotypic hippocampal slice cultures as a model of acute perinatal brain injury, serial imaging demonstrated that the capacity for microglial phagocytosis of dying neurons was overwhelmed for two weeks. Altering phagocytosis rates, e.g. by changing the number of microglia, dramatically changed the number of visibly dying neurons. Similar effects were generated when the visibility of dying neurons was altered by changing the membrane permeability for vital stains. Canonically neuroprotective interventions such as seizure blockade and neurotoxic maneuvers such as perinatal ethanol exposure were mediated by effects on microglial activity and the membrane permeability of apoptotic neurons, and had either no or opposing effects on healthy surviving neurons. Significance After acute brain injury, microglial phagocytosis is overwhelmed by the number of dying cells. Under these conditions, the assumptions on which assays for neuroprotective and neurotoxic effects are based are no longer valid. Thus longitudinal assays of healthy cells, such as assessment of the fluorescence emission of transgenically-expressed proteins, provide more accurate estimates of cell death than do single-time-point anatomical or biochemical assays. More accurate estimates of death rates will increase the translatability of preclinical studies of neuroprotection and neurotoxicity.
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Guan L, Crasta KC, Maier AB. Assessment of cell cycle regulators in human peripheral blood cells as markers of cellular senescence. Ageing Res Rev 2022; 78:101634. [PMID: 35460888 DOI: 10.1016/j.arr.2022.101634] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 12/12/2022]
Abstract
Cellular senescence has gained increasing interest during recent years, particularly due to causal involvement in the aging process corroborated by multiple experimental findings. Indeed, cellular senescence considered to be one of the hallmarks of aging, is defined as a stable growth arrest predominantly mediated by cell cycle regulators p53, p21 and p16. Senescent cells have frequently been studied in the peripheral blood of humans due to its accessibility. This review summarizes ex vivo studies describing cell cycle regulators as markers of senescence in human peripheral blood cells, along with detection methodologies and associative studies examining demographic and clinical characteristics. The utility of techniques such as the quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), microarray, RNA sequencing and nCounter technologies for detection at the transcriptional level, along with Western blotting, enzyme-linked immunosorbent assay and flow cytometry at the translational level, will be brought up at salient points throughout this review. Notably, housekeeping genes or proteins serving as controls such as GAPDH and β-Actin, were found not to be stably expressed in some contexts. As such, optimization and validation of such genes during experimental design were recommended. In addition, the expression of cell cycle regulators was found to vary not only between different types of blood cells such as T cells and B cells but also between stages of cellular differentiation such as naïve T cells and highly differentiated T cells. On the other hand, the associations of the presence of cell cycle regulators with demographics (age, gender, ethnicity, and socioeconomic status), clinical characteristics (body mass index, specific diseases, disease-related parameters) and lifestyle vary in groups of participants. One envisions that increased understanding and insights into the assessment of cell cycle regulators as markers of senescence in human peripheral blood cells will help inform prognostication and clinical intervention in elderly individuals.
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Affiliation(s)
- Lihuan Guan
- Department of Medicine and Aged Care, @AgeMelbourne, The Royal Melbourne Hospital, The University of Melbourne, Victoria, Australia.
| | - Karen C Crasta
- Healthy Longevity Translational Researc h Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Physiology, National University of Singapore, Singapore; NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Agency for Science, Technology & Research (A⁎STAR), Institute of Molecular and Cell Biology (IMCB), Singapore.
| | - Andrea B Maier
- Department of Medicine and Aged Care, @AgeMelbourne, The Royal Melbourne Hospital, The University of Melbourne, Victoria, Australia; Healthy Longevity Translational Researc h Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Centre for Healthy Longevity, @AgeSingapore, National University Health System, Singapore; Department of Human Movement Sciences, @AgeAmsterdam, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, the Netherlands.
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Viryasova GM, Tatarskiy VV, Sheynov AA, Tatarskiy EV, Sud'ina GF, Georgieva SG, Soshnikova NV. PBAF lacking PHD domains maintains transcription in human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118525. [PMID: 31398409 DOI: 10.1016/j.bbamcr.2019.118525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 08/01/2019] [Accepted: 08/04/2019] [Indexed: 12/20/2022]
Abstract
The myeloid precursor cell differentiation requires an extensive chromatin remodeling. We show that the level of the PBAF chromatin remodeling complex decreases following the start of differentiation of myeloid precursors, becoming very low in the terminally differentiated peripheral blood (PB) neutrophils where it co-localizes with Pol II on the transcriptionally active chromatin. Previously, we have shown that the PHF10 subunit of the PBAF signature module has four isoforms, two of them (PHF10-P) contain a tandem of C-terminal PHD domains. We found that out of four PHF10 isoforms present in the myeloid precursor cells, only the PHF10-Ss isoform lacking PHD domains, is actively expressed in the PB neutrophils. In particular, the longest of the PHF10 isoforms (PHF10-Pl), which is essential for proliferation, completely disappears in PB neutrophils. In addition, in the myeloid precursors, promoters of neutrophil-specific genes are associated with the PHD-containing isoforms, together with PBAF and Pol II, when these genes are inactive and only during their activation stage. However, at the later stages of differentiation, when neutrophil-specific genes are actively transcribed, PHF10-P isoforms on their promoters are replaced by the PHF10-S isoforms. Evidently, PHD domains of PHF10 are essential for active chromatin remodeling during transcription activation, but are dispensable for the constantly transcribed genes.
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Affiliation(s)
- Galina M Viryasova
- Department of Eukaryotic Transcription Factors, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia; The A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory, 1, Building 40, Moscow 119992, Russia
| | - Victor V Tatarskiy
- Department of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia
| | - Andrey A Sheynov
- Department of Eukaryotic Transcription Factors, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia
| | - Eugene V Tatarskiy
- Department of Eukaryotic Transcription Factors, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia
| | - Galina F Sud'ina
- The A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory, 1, Building 40, Moscow 119992, Russia
| | - Sofia G Georgieva
- Department of Eukaryotic Transcription Factors, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia.
| | - Nataliya V Soshnikova
- Department of Eukaryotic Transcription Factors, Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia.
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