Biology subjects

Gregory-Ksander, M.

Publications and source records attributed to Gregory-Ksander, M..

4 recordsLinked to original sources

bioRxiv2026

A genome-scale ORF screen for resilience factors that protect the RPE and restore vision in aged mice

Aging is a complex phenomenon, yet therapeutic discovery has largely relied on testing individual hypothesis-driven targets. Here, we performed a genome-scale open reading frame (ORF) screen for oxidative-stress resistance in retinal pigment epithelium (RPE) cells, which are vulnerable to oxidative damage during aging. The screen identified nine protective ORFs including antioxidant factors and an epithelial-to-mesenchymal transition regulator. Notably, we also identified three factors that reduce transcriptomic age including the cardiac transcription factor NKX2-5. NKX2-5 conferred robust oxidative resilience in vitro and in vivo. Domain dissection revealed that its homeodomain is dispensable for resilience, enabling development of NKX2-5{Delta}HD, which retained protective activity without detectable toxicity over 14 months. In middle-aged mice, subretinal NKX2-5{Delta}HD restored visual and electrophysiological function, and its systemic delivery improved grip strength and reduced frailty in late-aged mice. These findings highlight the value of unbiased, genome-scale gain-of-function screening, as resilience factors normally expressed in other contexts can be reengineered as potential therapeutics for age-related decline in other tissues.

genetics↗

bioRxiv2025

Reprogramming Factors Activate a Non-Canonical Oxidative Resilience Pathway That Can Rejuvenate RPEs and Restore Vision

Oct4, Sox2, and Klf4 (OSK) Yamanaka factors induce pluripotency and reverse age-related epigenetic changes, yet the mechanisms by which they promote rejuvenation remain poorly explored. Oxidative stress contributes to CNS aging and retinal pigmented epithelium (RPE) degeneration in age-related macular degeneration. We find that OSK expression in RPE restores retinal structure and visual function in aged mice and promotes oxidative resilience through a non-canonical, Tet2-independent pathway. Integrative functional genomics identifies GSTA4, a detoxifying enzyme that clears the lipid peroxidation byproduct 4-HNE, as a necessary and sufficient OSK effector. Dynamic GSTA4 regulation by OSK recapitulates a stem cell derived stress resilience program. GSTA4 overexpression alone enhances mitochondrial resilience, rejuvenates the aged RPE transcriptome, and reverses visual decline. GSTA4 is consistently upregulated across diverse lifespan-extending interventions suggesting a broader pro-longevity role. These findings uncover a previously unrecognized protective axis driven by Yamanaka factors that circumvents reprogramming, providing therapeutic insights for age-related diseases. HIGHLIGHTSO_LIOSK-GSTA4 provides a dynamic, Tet2-independent stress-resilience axis. C_LIO_LIFunctional genomics pinpoints GSTA4 as a direct downstream effector activated by OSK. C_LIO_LIRPE aging involves progressive accumulation of 4-HNE that can be detoxified by GSTA4. C_LIO_LIEnhancing GSTA4 rejuvenates RPE cells, restores vision and is associated with lifespan-extending interventions. C_LI

genetics↗

bioRxiv2024

Modulation of microglia activation after human donor retinal ganglion cell transplantation

Stem cell-derived retinal ganglion cell transplantation therapy offers a promising avenue for restoring vision in patients with significant retinal ganglion cell loss. The major challenge in this therapeutic approach is ensuring the survival of transplanted human donor retinal ganglion cells within the host retina. Here, we demonstrated the pivotal role of host retinal microglia and macrophages in the rejection, acceptance and survival of human donor cells. To identify the potential targets for treatment in microglia-retinal ganglion cell interaction, we assembled a single-cell atlas for mouse retina during development, aging, maturation and across neurodegenerative conditions. To our knowledge, this is the largest integrated atlas containing 1,053,629 cells including 36,080 myeloid cells. The downstream analysis highlighted phagocytosis among other known pathways involved in microglia activation, neuroinflammation and host retinal ganglion cell damage. We hypothesized that the same mechanisms are responsible for donor retinal ganglion cell removal. We showed that it is possible to improve the survival of human donor stem cell-derived retinal ganglion cells through modulation of the host retinal microglia. Pretreatment of human donor retinal ganglion cells with annexin V and/or soluble Fas ligand before transplantation led to a 2.5-fold increase in donor cell survival, including the outgrowth of axons targeting optic nerve head. Detailed analyses of the host mouse retina post-transplantation revealed morphological changes microglia and macrophages typical for activation in neuroinflammation. These findings indicate that soluble Fas ligand and annexin V treatment can be used to improve the success rate of transplantation of neurons within the retina and central nervous system.

cell biology↗

bioRxiv2019

DNA Break-Induced Epigenetic Drift as a Cause of Mammalian Aging

There are numerous hallmarks of aging in mammals, but no unifying cause has been identified. In budding yeast, aging is associated with a loss of epigenetic information that occurs in response to genome instability, particularly DNA double-strand breaks (DSBs). Mammals also undergo predictable epigenetic changes with age, including alterations to DNA methylation patterns that serve as epigenetic \"age\" clocks, but what drives these changes is not known. Using a transgenic mouse system called \"ICE\" (for inducible changes to the epigenome), we show that a tissues response to non-mutagenic DSBs reorganizes the epigenome and accelerates physiological, cognitive, and molecular changes normally seen in older mice, including advancement of the epigenetic clock. These findings implicate DSB-induced epigenetic drift as a conserved cause of aging from yeast to mammals.\n\nOne Sentence SummaryDNA breaks induce epigenomic changes that accelerate the aging clock in mammals

molecular biology↗