Programmed cell death is well established as a key factor in the development of the vertebrate nervous system of which the retina is a unique sensory component. However, it is of utmost importance for the survival of post-mitotic tissues such as the retina that the execution of the cell death program is kept under stringent control once development is complete. This is exemplified by the many retinal dystrophies where aberrant apoptosis results in loss of distinct cell layers in the mature retina and often culminates in blindness. In this study, we report that the extracellular signal-regulated kinase (ERK1/2) pathway plays a key role in the regulation of apoptosis during retinal development. We show that as the retina matures, the emphasis shifts towards survival and ERK1/2 is activated resulting in phosphorylation of the potent BH3-only protein Bim(EL) and a dramatic decline in Bim(EL) expression via proteasomal degradation. We find that activation of ERK1/2 also occurs in response to injury in retinal explants. However, this is a transient response and appears to be overcome by Jun N-terminal kinase activation resulting in induction of Bim(EL) mRNA and photoreceptor apoptosis. Our findings provide new insights into the intracellular pathways responsible for regulating apoptosis during neuronal development and degeneration.
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http://dx.doi.org/10.1111/j.1471-4159.2010.07056.x | DOI Listing |
J Comp Neurol
January 2025
Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India.
Direction selectivity is a fundamental feature in the visual system. In the retina, direction selectivity is independently computed by ON and OFF circuits. However, the advantages of extracting directional information from these two independent circuits are unclear.
View Article and Find Full Text PDFCell Death Dis
January 2025
Laboratory of Developmental Cell Biology and Disease, State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China.
Epithelial-to-mesenchymal transition (EMT) is a critical and complex process involved in normal embryonic development, tissue regeneration, and tumor progression. It also contributes to retinal diseases, such as age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR). Although absent in melanoma 2 (AIM2) has been linked to inflammatory disorders, autoimmune diseases, and cancers, its role in the EMT of the retinal pigment epithelium (RPE-EMT) and retinal diseases remains unclear.
View Article and Find Full Text PDFCurr Top Dev Biol
January 2025
Center for Translational Vision Research, Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States; Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States; Department of Chemistry, University of California Irvine, Irvine, CA, United States; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States. Electronic address:
Vitamin A (all-trans-retinol; at-Rol) and its derivatives, known as retinoids, have been adopted by vertebrates to serve as visual chromophores and signaling molecules, particularly in the eye/retina. Few tissues rely on retinoids as heavily as the retina, and the study of genetically modified mouse models with deficiencies in specific retinoid-metabolizing proteins has allowed us to gain insight into the unique or redundant roles of these proteins in at-Rol uptake and storage, or their downstream roles in retinal development and function. These processes occur during embryogenesis and continue throughout life.
View Article and Find Full Text PDFCurr Top Dev Biol
January 2025
Development, Aging, and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States. Electronic address:
All-trans RA (ATRA) is a small molecule derived from retinol (vitamin A) that directly controls gene expression at the transcriptional level by serving as a ligand for nuclear ATRA receptors. ATRA is produced by ATRA-generating enzymes that convert retinol to retinaldehyde (retinol dehydrogenase; RDH10) followed by conversion of retinaldehyde to ATRA (retinaldehyde dehydrogenase; ALDH1A1, ALDH1A2, or ALDH1A3). Determining what ATRA normally does during vertebrate development has been challenging as studies employing ATRA gain-of-function (RA treatment) often do not agree with genetic loss-of-function studies that remove ATRA via knockouts of ATRA-generating enzymes.
View Article and Find Full Text PDFPLoS Pathog
January 2025
Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America.
The intracellular protozoan Toxoplasma gondii manipulates host cell signaling to avoid targeting by autophagosomes and lysosomal degradation. Epidermal Growth Factor Receptor (EGFR) is a mediator of this survival strategy. However, EGFR expression is limited in the brain and retina, organs affected in toxoplasmosis.
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