Biology subjects

Kuo, Y.-M.

Publications and source records attributed to Kuo, Y.-M..

10 recordsLinked to original sources

bioRxiv2026

PRSS56 acts as an intrinsic retinal signal driving postnatal ocular axial growth and myopia susceptibility

Myopia is a leading cause of visual impairment worldwide, and high myopia markedly increases the risk of irreversible vision loss. Although visual experience guides postnatal ocular elongation, the role of intrinsic retinal growth signals remains poorly defined. Here we identify the serine protease PRSS56 as a retinal factor that promotes ocular axial growth beyond early development. Using genetic mouse models, we show that conditional inactivation of Prss56 in Muller glia reduces axial length and causes hyperopia even under dark-rearing conditions, demonstrating that PRSS56 drives axial elongation independently of light-evoked visual input during emmetropization. Conversely, Muller glia-specific overexpression of Prss56 induces axial elongation in a proteolysis-dependent manner, supporting its role as an autonomous retinal growth signal. In concordance, human genetic analyses reveal that the common PRSS56 variant rs2853447 is associated with increased axial length in individuals with myopia and high myopia, but not in non-myopes, suggesting that this variant confers a selective growth advantage in individuals predisposed to ocular elongation. Functional genomic analyses further identify a myopia-associated variant, rs2741297, within a retinal enhancer in intron 4 of PRSS56 marked by open chromatin and transcription factor occupancy. Together, these findings establish PRSS56 as an intrinsic retinal growth factor that functions beyond early eye development and support a model in which genetic and environmental factors converge on retinal pathways to modulate myopia susceptibility.

genetics↗

bioRxiv2025

BBSome-Mediated Clearance of Ubiquitinated IMPG2 Defines a Constitutive Ciliary Retrieval Pathway in Photoreceptors

The BBSome mediates the retrieval of ubiquitinated membrane proteins from cilia, but its physiological cargoes in photoreceptors remain largely unidentified. Here, we find that K63-linked ubiquitin (UbK63) chains accumulate in the outer segment (OS, equivalent of cilia) of Bbs4-/- photoreceptors from the onset of OS formation. Through quantitative profiling of the UbK63-associated OS proteome, we identify the transmembrane fragment of interphotoreceptor matrix proteoglycan 2 (IMPG2m) as a principal cargo of the BBSome. In Bbs4-/- mice, ubiquitinated IMPG2m aberrantly accumulates in OSs, and disruption of IMPG2m ubiquitination impairs its retrieval and clearance. Because full-length IMPG2 traffics to the OS to deliver its extracellular domain to the matrix, our data support a model in which IMPG2m undergoes constitutive cycling between the inner and outer segments. These findings redefine the BBSomes role in photoreceptors from quality control to constitutive membrane protein turnover.

cell biology↗

bioRxiv2023

Integrative single-cell characterization of frugivory adaptations in the bat kidney and pancreas

Frugivory evolved multiple times in mammals, including bats. However, the cellular and molecular components driving it remain largely unknown. Here, we used integrative single-cell sequencing on insectivorous and frugivorous bat kidneys and pancreases and identified key cell population, gene expression and regulatory element differences associated with frugivorous adaptation that also relate to human disease, particularly diabetes. We found an increase in collecting duct cells and differentially active genes and regulatory elements involved in fluid and electrolyte balance in the frugivore kidney. In the frugivorous pancreas, we observed an increase in endocrine and a decrease in exocrine cells and differences in genes and regulatory elements involved in insulin regulation. Combined, our work provides novel insights into frugivorous adaptation that also could be leveraged for therapeutic purposes.

genomics↗

bioRxiv2022

Granulin Loss of Function in Human Mature Brain Organoids Implicates Astrocytes in TDP-43 Pathology

Loss of function (LoF) of Tar-binding protein 43 (TDP-43) and mislocalization, together with TDP-43-positive and hyperphosphorylated inclusions, are found in postmortem tissue of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) patients, including those carrying LoF variants in the progranulin gene (GRN). Modelling TDP-43 pathology has been challenging in vivo and in vitro. We present a 3D-induced pluripotent stem cell (iPSC)-derived paradigm - mature brain organoids (mbOrg) - composed of cortical-like-astrocytes (iA) and neurons (iN). When devoid of GRN, mbOrgs spontaneously recapitulate TDP-43 mislocalization, hyperphosphorylation and LoF phenotypes. Mixing-and-matching genotypes in mbOrgs showed that GRN-/- iA are drivers for TDP-43 pathology. Finally, we rescued TDP-43 LoF by adding exogenous progranulin, demonstrating a link between TDP-43 LoF and progranulin expression. In conclusion, we present an iPSC-derived platform that shows striking features of human TDP-43 proteinopathy and provides a tool for mechanistic modelling of TDP-43 pathology and patient-tailored therapeutic screening for FTD and ALS. HighlightsO_LIGRN-/- iPSC-derived 3D paradigm (mbOrg) composed of mature cortical-like astrocytes and neurons recapitulates features of TDP-43 proteinopathy C_LIO_LIGRN-/- cortical-like astrocytes are necessary and sufficient for the development of the TDP-43 loss of function phenotype in mbOrg. C_LIO_LIA TDP-43 phenotype can be rescued in neurons by treating neuron and astrocyte co-cultures with progranulin full length protein. C_LI eTOC blurbIn this article, de Majo and colleagues present a novel 3D iPSC-derived model to study neurodegenerative disorders such as ALS and FTD. When devoid of GRN expression, these cultures present features of ALS and FTD associated pathology hardly ever observed in vitro. These phenotypes are shown to be primarily driven by diseased astrocytes and can be rescued by progranulin supplementation.

neuroscience↗

bioRxiv2022

Novel Master Regulators of Microglial Phagocytosis and Repurposed FDA-approved Drug for Treatment of Alzheimer Disease

Microglia, the innate immune cells of the brain, are essential determinants of late-onset Alzheimers Disease (LOAD) neuropathology. Here, we developed an integrative computational systems biology approach to construct causal network models of genetic regulatory programs for microglia in Alzheimers Disease (AD). This model enabled us to identify novel key driver (KDs) genes for microglial functions that can be targeted for AD pharmacotherapy. We prioritized FCER1G, HCK, LAPTM5, ITGB2, SLC1A2, PAPLN, GSAP, NTRK2, and CIRBP as KDs of microglial phagocytosis promoting neuroprotection and/or neural repair. In vitro, shRNA knockdown of each KD significantly reduced microglial phagocytosis. We repurposed riluzole, an FDA-approved ALS drug that upregulates SLC1A2 activity, and discovered that it stimulated phagocytosis of A{beta}1-42 in human primary microglia and decreased hippocampal amyloid plaque burden/phosphorylated tau levels in the brain of aged 3xTg-AD mice. Taken together, these data emphasize the utlility of our integrative approach for repurposing drugs for AD therapy.

neuroscience↗

bioRxiv2021

Hypothermia Suppresses Uncoupling of Oxidative-Phosphorylation after Neonatal Cerebral Hypoxia-Ischemia

Hypoxia-ischemia (HI), which disrupts the oxygen supply-demand balance in the brain by impairing blood oxygen supply and the cerebral metabolic rate of oxygen (CMRO2), is a leading cause of neonatal brain injury. However, it is unclear how post-HI hypothermia helps to restore the balance, as cooling reduces CMRO2. Also, how transient HI leads to secondary energy failure (SEF) in neonatal brains remains elusive. Using photoacoustic microscopy, we examined the effects of HI on CMRO2 in awake 10-day-old mice, supplemented by bioenergetic analysis of purified cortical mitochondria. Our results show that while HI suppresses ipsilateral CMRO2, it sparks a prolonged CMRO2-surge post-HI, associated with increased mitochondrial oxygen consumption, superoxide emission, and reduced mitochondrial membrane potential necessary for ATP synthesis--indicating oxidative phosphorylation (OXPHOS) uncoupling. Post-HI hypothermia prevents the CMRO2-surge by constraining oxygen extraction fraction, reduces mitochondrial oxidative stress, and maintains ATP and N-acetylaspartate levels, resulting in attenuated infarction at 24 hours post-HI. Our findings suggest that OXPHOS-uncoupling induced by the post-HI CMRO2-surge underlies SEF and blocking the surge is a key mechanism of hypothermia protection. Also, our study highlights the potential of optical CMRO2-measurements for detecting neonatal HI brain injury and guiding the titration of therapeutic hypothermia at the bedside.

neuroscience↗

bioRxiv2021

Adropin confers neuroprotection and promotes functional recovery from ischemic stroke

Adropin is a highly-conserved peptide that has been shown to preserve endothelial barrier function. Blood-brain barrier (BBB) disruption is a key pathological event in cerebral ischemia. However, the effects of adropin on ischemic stroke outcomes remain unexplored. Hypothesizing that adropin exerts neuroprotective effects by maintaining BBB integrity, we investigated the role of adropin in stroke pathology utilizing loss- and gain-of-function genetic approaches combined with pharmacological treatment with synthetic adropin peptide. Stroke decreased endogenous adropin levels in the brain and plasma. Adropin treatment or transgenic adropin overexpression robustly reduced brain injury and improved long-term sensorimotor and cognitive function in young and aged mice subjected to ischemic stroke. In contrast, genetic deletion of adropin exacerbated ischemic brain injury. Mechanistically, adropin neuroprotection depends on endothelial nitric oxide synthase and is associated with reduced BBB permeability and neuroinflammation. We identify adropin as a novel neuroprotective peptide with the potential to improve stroke outcomes.

neuroscience↗

bioRxiv2021

GLIS1 regulates trabecular meshwork function and intraocular pressure and is associated with glaucoma in humans

Chronically elevated intraocular pressure (IOP) is the major risk factor of primary open- angle glaucoma, a leading cause of blindness. Dysfunction of the trabecular meshwork (TM), which controls the outflow of aqueous humor (AqH) from the anterior chamber, is the major cause of elevated IOP. Here, we demonstrate that mice deficient in the Kruppel- like zinc finger transcriptional factor GLI-similar-1 (GLIS1) develop chronically elevated IOP. Magnetic resonance imaging and histopathological analysis reveal that deficiency in GLIS1 expression induces progressive degeneration of the TM, leading to inefficient AqH drainage from the anterior chamber and elevated IOP. Transcriptome and cistrome analyses identified several glaucoma- and extracellular matrix-associated genes as direct transcriptional targets of GLIS1. We also identified a significant association between GLIS1 variant rs941125 and glaucoma in humans (P=4.73x10-6), further supporting a role for GLIS1 into glaucoma etiology. Our study identifies GLIS1 as a critical regulator of TM function and maintenance, AqH dynamics, and IOP.

molecular biology↗

bioRxiv2018

Two factor authorization: Asf1 mediates crosstalk between H3 K14 and K56 acetylation

Acetylation of histones plays a critical role in maintaining the epigenetic state of the eukaryotic cell. One such acetylation site critical for DNA damage repair is H3K56ac. In Saccharomyces cerevisiae, H3K56ac is thought to be driven mainly by Rtt109, a lysine acetyltransferase (KAT) that associates with the histone chaperones Vps75 and Asf1. Both of these chaperones can increase the specificity of histone acetylation by Rtt109, but neither alter the selectivity. It has been shown that histones extracted from cells (Drosophila), presumably containing pre-acetylated histones, can incorporate higher amounts of H3K56ac relative to recombinant non-acetylated histones. We hypothesized that histone pre-acetylation and histone chaperones could function together to drive acetylation of H3K56. In the present study, we test this hypothesis using a series of singly acetylated histones to determine the impact of crosstalk on enzyme selectivity. Our data suggest that crosstalk between acetylation sites plays a major role in altering the selectivity of Rtt109-Vps75 and that the histone chaperone Asf1 mediates this crosstalk. Specifically, we show that H3K14ac/H4 functions with Asf1 to drive H3K56ac by Rtt109-Vps75. We identified an acidic patch in Asf1 that mediates this cross-talk and show that mutations to this region can alter the Asf1 mediated crosstalk that changes Rtt109-Vps75 selectivity. These data explain the genetic link between Gcn5, which acetylates H3K14 and Rtt109. More broadly these data demonstrate that acetylation sites can dictate site selectivity even in the absence of a bromodomain and helps to explain the limited complexity that has been observed of the histone post-translational modifications patterns by global proteomic studies.

biochemistry↗

bioRxiv2018

T Cell Activation Triggers Reversible Inosine-5'-Monophosphate Dehydrogenase Assembly

T cell-mediated adaptive immunity requires naive, unstimulated T cells to transition from a quiescent metabolic state into a highly proliferative state upon T cell receptor engagement. This complex process depends on transcriptional changes mediated by Ca2+-dependent NFAT signaling, mTOR-mediated signaling and increased activity of the guanine nucleotide biosynthetic enzyme inosine-5-monophosphate (IMP) dehydrogenase (IMPDH). Inhibitors of these pathways serve as potent immunosuppressants. Unexpectedly, we discovered that all three pathways converge to promote the assembly of IMPDH protein into micron-scale macromolecular filamentous structures in response to T cell activation. Assembly is post-transcriptionally controlled by mTOR and the Ca2+ influx regulator STIM1. Furthermore, IMPDH assembly and catalytic activity were negatively regulated by guanine nucleotide levels, suggesting a negative feedback loop that limits biosynthesis of guanine nucleotides. Filamentous IMPDH may be more resistant to this inhibition, facilitating accumulation of the higher GTP levels required for T cell proliferation.

immunology↗