---
_id: '14401'
abstract:
- lang: eng
text: "Background: \r\nPro-apoptotic BAX is a central mediator of retinal ganglion
cell (RGC) death after optic nerve damage. BAX activation occurs in two stages
including translocation of latent BAX to the mitochondrial outer membrane (MOM)
and then permeabilization of the MOM to facilitate the release of apoptotic signaling
molecules. As a critical component of RGC death, BAX is an attractive target for
neuroprotective therapies and an understanding of the kinetics of BAX activation
and the mechanisms controlling the two stages of this process in RGCs is potentially
valuable in informing the development of a neuroprotective strategy.\r\nMethods:\r\nThe
kinetics of BAX translocation were assessed by both static and live-cell imaging
of a GFP-BAX fusion protein introduced into RGCs using AAV2-mediated gene transfer
in mice. Activation of BAX was achieved using an acute optic nerve crush (ONC)
protocol. Live-cell imaging of GFP-BAX was achieved using explants of mouse retina
harvested 7 days after ONC. Kinetics of translocation in RGCs were compared to
GFP-BAX translocation in 661W tissue culture cells. Permeabilization of GFP-BAX
was assessed by staining with the 6A7 monoclonal antibody, which recognizes a
conformational change in this protein after MOM insertion. Assessment of individual
kinases associated with both stages of activation was made using small molecule
inhibitors injected into the vitreous either independently or in concert with
ONC surgery. The contribution of the Dual Leucine Zipper-JUN-N-Terminal Kinase
cascade was evaluated using mice with a double conditional knock-out of both Mkk4
and Mkk7.\r\nResults:\r\nONC induces the translocation of GFP-BAX in RGCs at a
slower rate and with less intracellular synchronicity than 661W cells, but exhibits
less variability among mitochondrial foci within a single cell. GFP-BAX was also
found to translocate in all compartments of an RGC including the dendritic arbor
and axon. Approximately 6% of translocating RGCs exhibited retrotranslocation
of BAX immediately following translocation. Unlike tissue culture cells, which
exhibit simultaneous translocation and permeabilization, RGCs exhibited a significant
delay between these two stages, similar to detached cells undergoing anoikis.
Translocation, with minimal permeabilization could be induced in a subset of RGCs
using an inhibitor of Focal Adhesion Kinase (PF573228). Permeabilization after
ONC, in a majority of RGCs, could be inhibited with a broad spectrum kinase inhibitor
(sunitinib) or a selective inhibitor for p38/MAPK14 (SB203580). Intervention of
DLK-JNK axis signaling abrogated GFP-BAX translocation after ONC.\r\nConclusions:\r\nA
comparison between BAX activation kinetics in tissue culture cells and in cells
of a complex tissue environment shows distinct differences indicating that caution
should be used when translating findings from one condition to the other. RGCs
exhibit both a delay between translocation and permeabilization and the ability
for translocated BAX to be retrotranslocated, suggesting several stages at which
intervention of the activation process could be exploited in the design of a therapeutic
strategy."
acknowledgement: "The authors would like to thank Mr. Joel Dietz for management of
the mouse colony and helpful advice for conducting quantitative PCR studies and
Mr. Santoshi Kinoshita at the Translational Research Initiative in Pathology laboratory
at the University of Wisconsin-Madison for cutting sections analyzed in this study.\r\nThis
work was supported by National Eye Institute grants R01 EY030123 (RWN), R01 EY018606
(RTL), P30 EY016665 (Department of Ophthalmology and Visual Sciences, University
of Wisconsin-Madison), T32 EY027721 (RJD) and F31 EY030739 (OJM). Additional funding
was provided by the BrightFocus Foundation (RWN) and unrestricted grants from Research
to Prevent Blindness, Inc to the Department of Ophthalmology and Visual Sciences
(University of Wisconsin-Madison) and to the Department of Ophthalmology (University
of Rochester)."
article_number: '67'
article_processing_charge: Yes
article_type: original
author:
- first_name: Margaret E
full_name: Maes, Margaret E
id: 3838F452-F248-11E8-B48F-1D18A9856A87
last_name: Maes
orcid: 0000-0001-9642-1085
- first_name: Ryan J.
full_name: Donahue, Ryan J.
last_name: Donahue
- first_name: Cassandra L.
full_name: Schlamp, Cassandra L.
last_name: Schlamp
- first_name: Olivia J.
full_name: Marola, Olivia J.
last_name: Marola
- first_name: Richard T.
full_name: Libby, Richard T.
last_name: Libby
- first_name: Robert W.
full_name: Nickells, Robert W.
last_name: Nickells
citation:
ama: Maes ME, Donahue RJ, Schlamp CL, Marola OJ, Libby RT, Nickells RW. BAX activation
in mouse retinal ganglion cells occurs in two temporally and mechanistically distinct
steps. Molecular Neurodegeneration. 2023;18. doi:10.1186/s13024-023-00659-8
apa: Maes, M. E., Donahue, R. J., Schlamp, C. L., Marola, O. J., Libby, R. T., &
Nickells, R. W. (2023). BAX activation in mouse retinal ganglion cells occurs
in two temporally and mechanistically distinct steps. Molecular Neurodegeneration.
Springer Nature. https://doi.org/10.1186/s13024-023-00659-8
chicago: Maes, Margaret E, Ryan J. Donahue, Cassandra L. Schlamp, Olivia J. Marola,
Richard T. Libby, and Robert W. Nickells. “BAX Activation in Mouse Retinal Ganglion
Cells Occurs in Two Temporally and Mechanistically Distinct Steps.” Molecular
Neurodegeneration. Springer Nature, 2023. https://doi.org/10.1186/s13024-023-00659-8.
ieee: M. E. Maes, R. J. Donahue, C. L. Schlamp, O. J. Marola, R. T. Libby, and R.
W. Nickells, “BAX activation in mouse retinal ganglion cells occurs in two temporally
and mechanistically distinct steps,” Molecular Neurodegeneration, vol.
18. Springer Nature, 2023.
ista: Maes ME, Donahue RJ, Schlamp CL, Marola OJ, Libby RT, Nickells RW. 2023. BAX
activation in mouse retinal ganglion cells occurs in two temporally and mechanistically
distinct steps. Molecular Neurodegeneration. 18, 67.
mla: Maes, Margaret E., et al. “BAX Activation in Mouse Retinal Ganglion Cells Occurs
in Two Temporally and Mechanistically Distinct Steps.” Molecular Neurodegeneration,
vol. 18, 67, Springer Nature, 2023, doi:10.1186/s13024-023-00659-8.
short: M.E. Maes, R.J. Donahue, C.L. Schlamp, O.J. Marola, R.T. Libby, R.W. Nickells,
Molecular Neurodegeneration 18 (2023).
date_created: 2023-10-08T22:01:15Z
date_published: 2023-09-26T00:00:00Z
date_updated: 2024-01-30T14:34:21Z
day: '26'
ddc:
- '570'
department:
- _id: SaSi
doi: 10.1186/s13024-023-00659-8
external_id:
isi:
- '001071403800001'
pmid:
- '37292963'
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oa_version: Published Version
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publication: Molecular Neurodegeneration
publication_identifier:
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publication_status: published
publisher: Springer Nature
quality_controlled: '1'
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status: public
title: BAX activation in mouse retinal ganglion cells occurs in two temporally and
mechanistically distinct steps
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 18
year: '2023'
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