Biology subjects

John, S. W.

Publications and source records attributed to John, S. W..

6 recordsLinked to original sources

bioRxiv2026

Molecular profiling implicates immune-driven adaptive homeostasis in maintaining intraocular pressure with age

Aging and ocular hypertension are primary risk factors for glaucoma - a major cause of blindness worldwide. Ocular hypertension results from dysfunction in the outflow tissues - the trabecular meshwork (TM) and Schlemm's canal (SC), which are key regulators of intraocular pressure (IOP) homeostasis. Despite lifelong multifaceted stress to the outflow pathway, ocular hypertension sufficient to develop glaucoma occurs in only a minority of individuals. The mechanisms that preserve physiological IOP with aging in most individuals remain poorly understood. Using single-cell RNA sequencing and protein validation in mouse outflow tissues, we found that aging is accompanied by subtype-specific changes in TM cells, including altered extracellular matrix maintenance, reduced trophic signaling to SC, and increased profibrotic signaling. Coincident with these changes, we observed age-dependent immune remodeling, marked by increased macrophage abundance in outflow tissues. Our model predicts that macrophages maintain SC homeostasis via VEGFA signaling - normally supplied by the TM and required for normal SC function, but impaired with age. This pattern supports a paradigm in which adaptive immune remodeling contributes to preserving IOP homeostasis despite progressive aging-associated cellular dysfunction. More broadly, we identify the TM/SC outflow pathway as a model for understanding how aging tissues preserve physiological function through coordinated structural, trophic, and adaptive immune remodeling.

cell biology↗

bioRxiv2026

Developing Potent and Selective TBK1 Molecular Glue Degraders for Cancer Immunotherapy

Immune checkpoint blockade (ICB) has transformed cancer therapy across multiple tumour types, yet primary and acquired resistance remain major barriers to durable benefit. TANK-binding kinase 1 (TBK1) has emerged as an attractive target to enhance anti-tumour immunity, acting as a serine/threonine kinase that restrains immunogenic cell death and downstream immune activation. Here we report the discovery of a first-in-class TBK1 molecular glue degrader (MGD), CCT412020, identified through high-throughput proteomics screening of a next-generation molecular glue library. CCT412020 induces rapid, potent and selective TBK1 degradation across a panel of breast cancer cell lines. A cryo-EM structure of CCT412020 in complex with CRBN/{Delta}BPB-DDB1 and TBK1-homodimer reveals an unexpected binding mode that bypasses the canonical G-loop and instead engages an unconventional site at the TBK1 homodimer interface. Functionally, TBK1 loss via CCT412020 sensitises tumour cells to TNF- and interferon-driven responses and reduced viability across a broad range of cancer cell lines. Together, these findings establish CCT412020 as a mechanistically distinct TBK1 degrader and provide a framework for developing TBK1-targeted degraders as immunomodulatory anti-cancer agents to overcome ICB resistance.

cancer biology↗

bioRxiv2020

Genetic background modifies vulnerability to glaucoma related phenotypes in Lmx1b mutant mice

Variants in the LIM homeobox transcription factor 1-beta gene (LMX1B) predispose individuals to elevated intraocular pressure (IOP), a key risk factor for glaucoma. However, the effect of LMX1B mutations varies widely between individuals. To better understand mechanisms underlying LMX1B-related phenotypes and individual differences, we backcrossed the Lmx1bV265D (also known as Lmx1bIcst) allele onto the C57BL/6J (B6), 129/Sj (129), C3A/BLiA-Pde6b+/J (C3H), and DBA/2J-Gpnmb+ (D2-G) strain backgrounds. Strain background had a significant effect on the onset and severity of ocular phenotypes in Lmx1bV265D/+ mutant mice. Mice of the B6 background were the most susceptible to developing elevated IOP, severe anterior segment developmental anomalies (including malformed eccentric pupils, iridocorneal strands, and corneal abnormalities) and glaucomatous nerve damage. In contrast, Lmx1bV265D mice of the 129 background were the most resistant to developing anterior segment abnormalities, had less severe IOP elevation than B6 mutants at young ages, and showed no detectable nerve damage. To identify genetic modifiers of susceptibility to Lmx1bV265D-induced glaucoma-associated phenotypes, we performed a mapping cross between mice of the B6 (susceptible) and 129 (resistant) backgrounds. We identified a modifier locus on Chromosome 18, with the 129 allele(s) substantially lessening severity of ocular phenotypes, as confirmed by congenic analysis. By demonstrating a clear effect of genetic background in modulating Lmx1b-induced phenotypes, by providing a panel of strains with different phenotypic severities and by identifying a modifier locus, this study lays a foundation for better understanding the roles of LMX1B in glaucoma with the goal of developing new treatments.

genetics↗

bioRxiv2020

Oral pyruvate prevents glaucomatous neurodegeneration

Intraocular pressure-sensitive retinal ganglion cell degeneration is a hallmark of glaucoma, the leading cause of irreversible blindness. Converging evidence indicates that age-related bioenergetic insufficiency increases the vulnerability of retinal ganglion cells to intraocular pressure. To investigate further, we used metabolomics and RNA-sequencing to examine early glaucoma in DBA/2J mice. We demonstrate an intraocular pressure-dependent decline in retinal pyruvate levels coupled to dysregulated glucose metabolism prior to detectable optic nerve degeneration. Oral supplementation of pyruvate strongly protected from neurodegeneration in pre-clinical models of glaucoma. We detected mTOR activation at the mechanistic nexus of neurodegeneration and metabolism. Rapamycin-induced inhibition of mTOR robustly prevented glaucomatous neurodegeneration. Bioenergetic enhancement, in combination with intraocular pressure reduction, therefore provides a readily translatable strategy that warrants investigation in clinical trials. FundingVetenskapsr[a]det 2018-02124 and StratNeuro StartUp grant (PAW). Pete Williams is supported by the Karolinska Institutet in the form of a Board of Research Faculty Funded Career Position and by St. Erik Eye Hospital philanthropic donations. EY011721 and the Barbra and Joseph Cohen Foundation and startup funds from Columbia University (SWMJ). Simon John is an Investigator of HHMI.

neuroscience↗

bioRxiv2019

Suppression of homeostatic gene expression and increased expression of metabolism-related genes are early features of glaucoma in optic nerve head microglia

Glaucoma is the leading cause of irreversible vision loss. Ocular hypertension is a major risk factor for glaucoma and recent work has demonstrated critical early neuroinflammatory insults occur in the optic nerve head following ocular hypertension. Microglia and infiltrating monocytes are likely candidates to drive these neuroinflammatory insults. However, the exact molecular identity / transcriptomic profile of microglia early following ocular hypertensive insults is unknown. To elucidate the molecular identity of microglia during early glaucoma pathogenesis, we performed RNA-sequencing of microglia mRNA from the optic nerve head of a genetic mouse model of glaucoma (DBA/2J) at a time point following ocular hypertensive insults, but preceding detectable neurodegeneration (with microglia identified as being CD45lo/CD11b+/CD11c-). Furthermore, RNA-sequencing was performed on optic nerve head microglia from mice treated with radiation therapy, a potent therapy preventing neuroinflammatory insults. Transcriptomic profiling of optic nerve head microglia mRNA identifies early metabolic priming with marked changes in mitochondrial gene expression, and changes to phagocytosis, inflammatory, and sensome pathways. The data predict that many functions of microglia that help maintain tissue homeostasis are affected. Comparative analysis of these data with data from previously published whole optic nerve head tissue or monocyte-only samples from DBA/2J mice demonstrate that many of the neuroinflammatory signatures in these data sets arise from infiltrating monocytes and not reactive microglia. Finally, our data demonstrate that radiation therapy of DBA/2J mice potently abolishes these microglia metabolic transcriptomic changes at the same time points. Together, our data provide a unique resource for the community to help drive further hypothesis generation and testing in glaucoma.

neuroscience↗

bioRxiv2018

PRSS56 is required for the developmental positioning of ocular angle structures

Angle-closure glaucoma (ACG) is a severe form of glaucoma affecting up to 16 million people worldwide. In ACG, physical blockage of the ocular drainage tissue by the peripheral iris impedes the drainage of aqueous humor resulting in elevated intraocular pressure (IOP) and subsequent optic nerve damage. Despite the high prevalence of ACG, the precise mechanism(s) underlying pathogenesis are only partially understood. We have previously demonstrated that a mutation in the gene encoding the serine protease PRSS56 causes an ACG phenotype in mice. Notably, Prss56 mutant mice exhibit a reduced ocular axial length and a lens occupying a larger ocular volume compared to WT mice, recapitulating characteristic features of human AGC. Our findings utilizing mouse genetic models demonstrate that loss of PRSS56 function results in altered configuration of ocular angle structures characterized by a posterior shift in the positioning of the ocular drainage tissue relative to the ciliary body and iris during development, leading to a physical blockage of drainage structure (angle closure) and high IOP. Utilizing a previously employed genetic strategy of rescuing mutant Prss56 mediated reduction in ocular size by inactivation of EGR1 (Egr1;Prss56 double mutants) we determined the influence of ocular size on developmental positioning of the ocular angle tissues. Our findings suggest that abnormal positioning of the drainage structure as a result of loss of PRSS56 function is uncoupled from its effect on ocular axial length reduction. Furthermore, we demonstrate that the IOP elevation observed in Prss56 mutant mice is genetic context-dependent and identify a dominant modifier locus on Chromosome 2 of the C3H/HeJ genome conferring susceptibility to high IOP. Overall, our findings reveal a novel role for PRSS56 in the proper configuration of the iridocorneal angle and provide new insight into the developmental pathways implicated in glaucoma pathogenesis.

genetics↗