Biology subjects

Park, E. S.

Publications and source records attributed to Park, E. S..

5 recordsLinked to original sources

bioRxiv2026

Adipocyte Expression of O-Glycoprotein Procollagen C-Endopeptidase Enhancer Protein 2 (PCPE2): Mechanisms Linking Fibrosis and Beiging of White Adipose Tissue

BackgroundProcollagen C-endopeptidase enhancer protein 2 (Pcpe2) has been primarily investigated in collagen processing during wound healing and is assumed to function similarly to Pcpe1 in the extracellular matrix (ECM). Our studies suggest that Pcpe2 has unique structural and functional features not shared with Pcpe1. MethodsTo study the role of Pcpe2 in adipose tissue remodeling, we created adipose tissue-specific knockout of Pcpe2 (TgAd+Pcpe2KO) and adipose tissue-specific Pcpe2 overexpressing (TgAd+Pcpe2Ox) mice and performed in vivo and ex vivo experiments. ResultsWe show that TgAd+Pcpe2KO mice are resistant to WD-induced obesity and exhibit reductions in body and fat pad mass. Promethion cage studies showed no significant differences in lean mass or food intake, yet WD-fed TgAd+Pcpe2KO mice exhibited significantly higher energy expenditure than negative Cre littermate controls. WD-fed TgAd+Pcpe2KO mice also showed reduced plasma glucose and lipoprotein lipid concentrations compared to controls. While markers of adipose tissue inflammation were reduced in WD-fed TgAd+Pcpe2KO mice. Examination of mature adipocytes from white adipose tissue showed that WD consumption greatly stimulated Pcpe2 expression, while no change in Pcpe2 expression in the stromal vascular cells was noted. However, in VAT precursor cells (PCs), the CD140b+ population showed a shift from fibroadipogenic precursors towards adipocyte PCs in TgAd+Pcpe2KO mice. This shift in PCs may account for the attenuation of local inflammation and fibrosis in the absence of Pcpe2. Ex vivo differentiation of adipose PCs showed that loss of Pcpe2 enhanced adipocyte differentiation, reducing TGF{beta}-like signaling via pSmad2/3, and increasing mitochondrial function. Furthermore, unlike Pcpe1, Pcpe2 contains a mucin-like linker domain with nine sites of O-linked glycosylation which may regulate receptor signaling at the plasma membrane. ConclusionsOur results show the ECM O-glycoprotein Pcpe2 is a robust marker of unhealthy adipose tissue expansion in humans and mice and contributes to inflammation and fibrosis associated with WD-induced obesity.

cell biology↗

bioRxiv2024

Shc1 cooperates with Frs2 and Shp2 to recruit Grb2 in FGF-induced lens development

Fibroblast growth factor (FGF) signaling elicits multiple downstream pathways, most notably the Ras/MAPK cascade facilitated by the adaptor protein Grb2. However, the mechanism by which Grb2 is recruited to the FGF signaling complex remains unresolved. Here we showed that genetic ablation of FGF signaling prevented lens induction by disrupting transcriptional regulation and actin cytoskeletal arrangements, which could be reproduced by deleting the juxtamembrane region of the FGF receptor and rescued by Kras activation. Conversely, mutations affecting the Frs2-binding site on the FGF receptor or the deletion of Frs2 and Shp2 primarily impact later stages of lens vesicle development involving lens fiber cell differentiation. Our study further revealed that the loss of Grb2 abolished MAPK signaling, resulting in a profound arrest of lens development. However, removing Grb2s putative Shp2 dephosphorylation site (Y209) neither produced a detectable phenotype nor impaired MAPK signaling during lens development. Furthermore, the catalytically inactive Shp2 mutation (C459S) only modestly impaired FGF signaling, whereas replacing Shp2s C-terminal phosphorylation sites (Y542/Y580) previously implicated in Grb2 binding only caused placental defects, perinatal lethality, and reduced lacrimal gland branching without impacting lens development, suggesting that Shp2 only partially mediates Grb2 recruitment. In contrast, we observed that FGF signaling is required for the phosphorylation of the Grb2-binding sites on Shc1 and the deletion of Shc1 exacerbates the lens vesicle defect caused by Frs2 and Shp2 deletion. These findings establish Shc1 as a critical collaborator with Frs2 and Shp2 in targeting Grb2 during FGF signaling.

developmental biology↗

bioRxiv2020

A neural m6A/YTHDF pathway is required for learning and memory in Drosophila

The roles of epitranscriptomic modifications in mRNA regulation have recently received substantial attention, with appreciation growing for their phenotypically selective impacts within the animal. We adopted Drosophila melanogaster as a model system to study m6A, the most abundant internal modification of mRNA. Here, we report proteomic and functional analyses of fly m6A-binding proteins, confirming nuclear (YTHDC) and cytoplasmic (YTHDF) YTH domain proteins as the major m6A binders. Since all core m6A pathway mutants are viable, we assessed in vivo requirements of the m6A pathway in cognitive processes. Assays of short term memory revealed an age-dependent requirement of m6A writers working via YTHDF, but not YTHDC, comprising the first phenotypes assigned to Drosophila mutants of the cytoplasmic m6A reader. These factors promote memory via neural-autonomous activities, and are required in the mushroom body, the center for associative learning. To inform their basis, we mapped m6A from wild-type and mettl3 null mutant heads, allowing robust discrimination of Mettl3-dependent m6A sites. In contrast to mammalian m6A, which is predominant in 3 UTRs, Drosophila m6A is highly enriched in 5 UTRs and occurs in an adenosine-rich context. Genomic analyses demonstrate that Drosophila m6A does not directionally affect RNA stability, but is preferentially deposited on genes with low translational efficiency. However, functional tests indicate a role for m6A in translational activation, since we observe reduced nascent protein synthesis in mettl3-KO cells. Finally, we show that ectopic YTHDF can increase m6A target reporter output in an m6A-binding dependent manner, and that this activity is required for in vivo neural function of YTHDF in memory. Altogether, we provide the first tissue-specific m6A maps in this model organism and reveal selective behavioral and translational defects for m6A/YTHDF mutants.

animal behavior and cognition↗

bioRxiv2020

Lossless Immunocytochemistry using Photo-polymerized Hydrogel Thin-films

Immunocytochemistry (ICC), or immunofluorescence microscopy, is an essential biological technique for phenotyping cells in both research and diagnostic applications. Standard ICC methods often do not work well when the cell sample contains a small number of cells (<10,000) because of the significant cell loss that occurs during washing, staining, and centrifugation steps. Cell loss is particularly relevant when working with rare cells, such as circulating tumor cells, where such losses could significantly bias experimental outcomes. In order to eliminate cell loss in ICC protocols, we present a method to encapsulate the cell sample in a photo-polymerized hydrogel thin-film. The hydrogel thin-film is permeable to antibodies and other ICC reagents, thereby allowing the use of standard ICC protocols without modification. The cell sample is physically constrained by the hydrogel at the bottom surface of a standard (unmodified) imaging microtiter plate, thereby enabling the acquisition of high-quality micrographs regardless of the properties of the cell sample or staining reagents. Furthermore, while standard ICC requires several centrifugation steps during staining and washing, our hydrogel encapsulation method requires only a single centrifugation step. This property greatly reduces the time required to perform ICC protocols and is more compatible with robotic platforms. In this study, we show that standard ICC and Cytospin protocols are extremely lossy (>70% loss) when the sample contains less than 10,000 cells, while encapsulating the cells using a permeable hydrogel thin-film results in a lossless ICC process.

bioengineering↗

bioRxiv2019

Microglial homeostasis requires balanced CSF-1/CSF-2 receptor signaling

CSF-1R haploinsufficiency causes adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). Previous studies in the Csf1r+/- mouse model of ALSP hypothesized a central role of elevated cerebral Csf2 expression. Here we show that monoallelic deletion of Csf2 rescues most behavioral deficits and histopathological changes in Csf1r+/- mice by preventing microgliosis and eliminating most microglial transcriptomic alterations, including those indicative of oxidative stress and demyelination. We also show elevation of Csf2 transcripts and of several CSF-2 downstream targets in the brains of ALSP patients, demonstrating that the mechanisms identified in the mouse model are functional in man. Our data provide new insights into the mechanisms underlying ALSP. Since both increased CSF2 levels and decreased microglial Csf1r expression have also been reported in Alzheimers disease and multiple sclerosis, we suggest that the unbalanced CSF-1R/CSF-2 signaling we describe in the present study may contribute to the pathogenesis of other neurodegenerative conditions. HighlightsO_LIALSP is a CSF1R-deficiency dementia associated with increased CSF2 expression C_LIO_LIIn Csf1r+/- ALSP mice CSF-2 promotes microgliosis by direct signaling in microglia C_LIO_LITargeting Csf2 improves cognition, myelination and normalizes microglial function C_LIO_LICSF-2 is a therapeutic target in ALSP C_LI

neuroscience↗