scholarly journals In situ and transcriptomic identification of synapse-associated microglia in the developing zebrafish brain

2021 ◽  
Author(s):  
Nicholas J Silva ◽  
Leah C Dorman ◽  
ilia vainchtein ◽  
Nadine C Horneck ◽  
Anna V Molofsky
Keyword(s):  
Optic Tectum ◽  
Apoptotic Cell ◽  
Synaptic Proteins ◽  
Mrna Sequencing ◽  
Zebrafish Brain ◽  
Synaptic Remodeling ◽  
Cathepsin Activity ◽  
Cell Engulfment ◽  
Model Circuit

Microglia are brain resident macrophages that play vital roles in central nervous system (CNS) development, homeostasis, and pathology. Microglia both remodel synapses and engulf apoptotic cell corpses during development, but whether unique molecular programs regulate these distinct phagocytic functions is unknown. Here we identify a molecularly distinct synapse-associated microglial subset in the zebrafish (Danio rerio). We found that ramified microglia populated synapse-rich regions of the midbrain and hindbrain between 7 and 28 days post fertilization. In contrast, microglia in the optic tectum were ameboid and clustered around neurogenic zones. Using single-cell mRNA sequencing combined with metadata from regional bulk sequencing, we identified synapse-associated microglia (SAMs) that were highly enriched in the hindbrain, expressed known synapse modulating genes as well as novel candidates, and engulfed synaptic proteins. In contrast, neurogenic-associated microglia (NAMs) were enriched in optic tectum, had active cathepsin activity, and preferentially engulfed neuronal corpses. These data yielded a functionally annotated atlas of zebrafish microglia (https://www.annamolofskylab.org/microglia-sequencing). Furthermore, they reveal that molecularly distinct phagocytic programs mediate synaptic remodeling and cell engulfment, and establish zebrafish hindbrain as a model circuit for investigating microglial-synapse interactions.

scholarly journals In situ and transcriptomic identification of microglia in synapse-rich regions of the developing zebrafish brain

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nicholas J. Silva ◽  
Leah C. Dorman ◽  
Ilia D. Vainchtein ◽  
Nadine C. Horneck ◽  
Anna V. Molofsky
Keyword(s):  
Danio Rerio ◽  
Optic Tectum ◽  
Apoptotic Cell ◽  
Mrna Sequencing ◽  
Zebrafish Brain ◽  
Synaptic Remodeling ◽  
Cathepsin Activity ◽  
Synaptic Region ◽  
Cell Engulfment

AbstractMicroglia are brain resident macrophages that play vital roles in central nervous system (CNS) development, homeostasis, and pathology. Microglia both remodel synapses and engulf apoptotic cell corpses during development, but whether unique molecular programs regulate these distinct phagocytic functions is unknown. Here we identify a molecularly distinct microglial subset in the synapse rich regions of the zebrafish (Danio rerio) brain. We found that ramified microglia increased in synaptic regions of the midbrain and hindbrain between 7 and 28 days post fertilization. In contrast, microglia in the optic tectum were ameboid and clustered around neurogenic zones. Using single-cell mRNA sequencing combined with metadata from regional bulk sequencing, we identified synaptic-region associated microglia (SAMs) that were highly enriched in the hindbrain and expressed multiple candidate synapse modulating genes, including genes in the complement pathway. In contrast, neurogenic associated microglia (NAMs) were enriched in the optic tectum, had active cathepsin activity, and preferentially engulfed neuronal corpses. These data reveal that molecularly distinct phagocytic programs mediate synaptic remodeling and cell engulfment, and establish the zebrafish hindbrain as a model for investigating microglial-synapse interactions.

scholarly journals Critical Effects on Akt Signaling in Adult Zebrafish Brain Following Alterations in Light Exposure

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 637
Author(s):  
Nicholas S. Moore ◽  
Robert A. Mans ◽  
Mackenzee K. McCauley ◽  
Colton S. Allgood ◽  
Keri A. Barksdale
Keyword(s):  
Optic Tectum ◽  
Visual Processing ◽  
Environmental Enrichment ◽  
Glycogen Synthase ◽  
Light Exposure ◽  
Hsp70 Expression ◽  
Light Cycle ◽  
Adult Zebrafish ◽  
Sleep State ◽  
Zebrafish Brain

Evidence from human and animal studies indicate that disrupted light cycles leads to alterations of the sleep state, poor cognition, and the risk of developing neuroinflammatory and generalized health disorders. Zebrafish exhibit a diurnal circadian rhythm and are an increasingly popular model in studies of neurophysiology and neuropathophysiology. Here, we investigate the effect of alterations in light cycle on the adult zebrafish brain: we measured the effect of altered, unpredictable light exposure in adult zebrafish telencephalon, homologous to mammalian hippocampus, and the optic tectum, a significant visual processing center with extensive telencephalon connections. The expression of heat shock protein-70 (HSP70), an important cell stress mediator, was significantly decreased in optic tectum of adult zebrafish brain following four days of altered light exposure. Further, pSer473-Akt (protein kinase B) was significantly reduced in telencephalon following light cycle alteration, and pSer9-GSK3β (glycogen synthase kinase-3β) was significantly reduced in both the telencephalon and optic tectum of light-altered fish. Animals exposed to five minutes of environmental enrichment showed significant increase in pSer473Akt, which was significantly attenuated by four days of altered light exposure. These data show for the first time that unpredictable light exposure alters HSP70 expression and dysregulates Akt-GSK3β signaling in the adult zebrafish brain.

scholarly journals Survivin in relation to Bcl-2, Bax and in situ apoptotic cell death in anaplastic thyroid carcinoma

2011 ◽  
Vol 63 (4) ◽  
pp. 955-963
Author(s):  
Sonja Selemetjev ◽  
Dubravka Cvejic ◽  
Svetlana Savin ◽  
I. Paunovic ◽  
S. Tatic
Keyword(s):  
Cell Death ◽  
Thyroid Carcinoma ◽  
Apoptotic Cell ◽  
Anaplastic Thyroid Carcinoma ◽  
Apoptotic Cell Death ◽  
Staining Score ◽  
Human Malignancy ◽  
Apoptotic Pathways ◽  
Individual Scores

Anaplastic thyroid carcinoma (ATC) is a rare but highly aggressive human malignancy. It is known that disturbances in apoptotic pathways have a great impact on tumor progression and aggressiveness. In this study the apoptosisrelated molecules Bcl-2 (antiapoptotic), Bax (proapoptotic) and survivin (an inhibitor of apoptosis) were analyzed immunohistochemically in thirty archival cases of ATC. In situ apoptotic cell death was analyzed by the TUNEL method. Mean Bcl-2 staining score (calculated from individual scores from 0-3) was low compared to those for Bax and survivin (p<0.05). High expression of survivin was associated with high Bax expression, and was significantly segregated from high Bcl-2 expressing cases (p<0.05). Despite high Bax expression, apoptotic cell death was low in the investigated carcinomas. In addition, the mean apoptotic index in high survivin expressing carcinomas was significantly lower than in low survivin expressing carcinomas (p<0.05). It could be concluded that down-regulation of Bcl-2 is counterbalanced by up-regulation of survivin, which may overcome the effects of high Bax expression, and, at least partly, explain the low apoptosis rate and high biological aggressiveness of ATC.

scholarly journals Impairment of Apoptotic Cell Engulfment by Pyocyanin, a Toxic Metabolite ofPseudomonas aeruginosa

2008 ◽  
Vol 177 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Stephen M. Bianchi ◽  
Lynne R. Prince ◽  
Kathleen McPhillips ◽  
Lucy Allen ◽  
Helen M. Marriott ◽  
...  
Keyword(s):  
Apoptotic Cell ◽  
Toxic Metabolite ◽  
Cell Engulfment

scholarly journals Two Alternative Mechanisms That Regulate the Presentation of Apoptotic Cell Engulfment Signal in Caenorhabditis elegans

2007 ◽  
Vol 18 (8) ◽  
pp. 3180-3192 ◽  
Author(s):  
Victor Venegas ◽  
Zheng Zhou
Keyword(s):  
Caenorhabditis Elegans ◽  
Abc Transporter ◽  
Germ Cells ◽  
Mammalian Cells ◽  
Developmental Stages ◽  
Apoptotic Cell ◽  
Somatic Cells ◽  
Apoptotic Cells ◽  
Phospholipid Scramblase ◽  
Cell Engulfment

Phosphatidylserine exposed on the surface of apoptotic mammalian cells is considered an “eat-me” signal that attracts phagocytes. The generality of using phosphatidylserine as a clearance signal for apoptotic cells in animals and the regulation of this event remain uncertain. Using ectopically expressed mouse MFG-E8, a secreted phosphatidylserine-binding protein, we detected specific exposure of phosphatidylserine on the surface of apoptotic cells in Caenorhabditis elegans. Masking the surface phosphatidylserine inhibits apoptotic cell engulfment. CED-7, an ATP-binding cassette (ABC) transporter, is necessary for the efficient exposure of phosphatidylserine on apoptotic somatic cells, and for the recognition of these cells by phagocytic receptor CED-1. Alternatively, phosphatidylserine exposure on apoptotic germ cells is not CED-7 dependent, but instead requires phospholipid scramblase PLSC-1, a homologue of mammalian phospholipid scramblases. Moreover, deleting plsc-1 results in the accumulation of apoptotic germ cells but not apoptotic somatic cells. These observations suggest that phosphatidylserine might be recognized by CED-1 and act as a conserved eat-me signal from nematodes to mammals. Furthermore, the two different biochemical activities used in somatic cells (ABC transporter) and germ cells (phospholipid scramblase) suggest an increased complexity in the regulation of phosphatidylserine presentation in response to apoptotic signals in different tissues and during different developmental stages.

scholarly journals Apoptosis in the Mouse Central Nervous System in Response to Infection with Mouse-Neurovirulent Dengue Viruses

1998 ◽  
Vol 72 (1) ◽  
pp. 823-829 ◽  
Author(s):  
Philippe Desprès ◽  
Marie-Pascale Frenkiel ◽  
Pierre-Emmanuel Ceccaldi ◽  
Claudia Duarte Dos Santos ◽  
Vincent Deubel
Keyword(s):  
Central Nervous System ◽  
Cell Death ◽  
Nervous System ◽  
Virus Infection ◽  
Virus Replication ◽  
Parental Strain ◽  
Apoptotic Cell ◽  
Neuronal Cell ◽  
Induced Apoptosis

ABSTRACT Apoptosis has been suggested as a mechanism by which dengue (DEN) virus infection may cause neuronal cell death (P. Desprès, M. Flamand, P.-E. Ceccaldi, and V. Deubel, J. Virol. 70:4090–4096, 1996). In this study, we investigated whether apoptotic cell death occurred in the central nervous system (CNS) of neonatal mice inoculated intracerebrally with DEN virus. We showed that serial passage of a wild-type human isolate of DEN virus in mouse brains selected highly neurovirulent variants which replicated more efficiently in the CNS. Infection of newborn mice with these neurovirulent variants produced fatal encephalitis within 10 days after inoculation. Virus-induced cell death and oligonucleosomal DNA fragmentation were observed in mouse brain tissue by day 9. Infected mouse brain tissue was assayed for apoptosis by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and for virus replication by immunostaining of viral antigens and in situ hybridization. Apoptotic cell death and DEN virus replication were restricted to the neurons of the cortical and hippocampal regions. Thus, DEN virus-induced apoptosis in the CNS was a direct result of virus infection. In the murine neuronal cell line Neuro 2a, neuroadapted DEN virus variants showed infection patterns similar to those of the parental strain. However, DEN virus-induced apoptosis in these cells was more pronounced after infection with the neurovirulent variants than after infection with the parental strain.

scholarly journals Differences in DNA Fragmentation following Transient Cerebral or Decapitation Ischemia in Rats

1995 ◽  
Vol 15 (5) ◽  
pp. 728-737 ◽  
Author(s):  
J. P. MacManus ◽  
I. E. Hill ◽  
E. Preston ◽  
I. Rasquinha ◽  
T. Walker ◽  
...  
Keyword(s):  
Dna Damage ◽  
Gel Electrophoresis ◽  
Time Course ◽  
Apoptotic Cell ◽  
Forebrain Ischemia ◽  
Dna Breaks ◽  
Double Labeling ◽  
Ca1 Region ◽  
Cell Death Pathway

The time course of appearance of cells with DNA damage was studied in rats following transient severe forebrain ischemia. This DNA damage could be detected by in situ end-labeling on brain sections. The breaks in DNA appeared selectively by day 1 in the striatum and later in the CA1 region of the hippocampus. It was possible by double labeling to show that there was no DNA damage in astrocytes. The DNA breaks consisted of laddered DNA fragments indicative of an ordered apoptotic type of internucleosomal cleavage, which persisted without smearing for up to 7 days of reperfusion. In contrast, the DNA breaks following ischemia induced by decapitation were random and, after gel electrophoresis, consisted of smeared fragments of multiple sizes. There was some early regional cellular death, restricted to the dentate of the hippocampus, prior to the pannecrotic degeneration. It is concluded that transient forebrain ischemia leads to a type of neuronal destruction that is not random necrosis but that shares some component of the apoptotic cell death pathway.

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