Biology subjects

Griffin, C. T.

Publications and source records attributed to Griffin, C. T..

8 recordsLinked to original sources

bioRxiv2025

TNFα and Endothelial IL-1 Receptor Signaling Drive Peritubular Capillary Regression and Fibrosis in Obstructive Kidney Injury

Capillary regression destabilizes tissue homeostasis and contributes to chronic organ dysfunction, yet the inflammatory pathways that drive pathological vessel loss remain incompletely defined. We previously identified the inflammatory cytokines TNF and IL-1 as conserved mediators of physiological vessel regression in the neonatal mouse eye, but whether these cytokines contribute to pathological capillary regression in adult mice is unknown. In this study, we investigated the capillary regression that occurs along with inflammation in murine kidneys following irreversible unilateral ureteral obstruction (UUO) surgical challenge. Mice lacking genes encoding global TNF, the endothelial IL-1 receptor IL-1R1, or both (double knockout, DKO) were examined at 10 days after UUO surgery. While loss of the individual genes did not affect peritubular capillary (PTC) regression, PTC regression was significantly reduced in DKO mice. This reduction in PTC regression correlated with less expression of the tubular epithelial injury marker KIM-1. DKO kidneys also displayed less fibrosis by Picrosirius Red and Massons trichrome staining. These findings demonstrate that TNF and endothelial IL-1R1 cooperatively drive pathological capillary regression in the irreversible UUO model of chronic kidney injury and that preservation of PTCs correlates with less renal tubular injury and fibrosis at 10 days after injury. NEW & NOTEWORTHYPathological PTC regression drives progressive kidney injury, but its inflammatory triggers are unclear. Using the UUO model, this study identifies cooperative TNF and endothelial IL-1R1 signaling as key drivers of capillary loss. While deletion of either pathway alone was insufficient, combined loss preserved PTCs, reduced tubular injury, and attenuated fibrosis. These findings highlight synergistic inflammatory signaling in microvascular loss and suggest dual targeting may help preserve PTC integrity in chronic kidney disease.

pathology↗

bioRxiv2025

Limb proportions predict aquatic habits and soft-tissue flippers in extinct amniotes

IN BRIEFGordon et al. use a phylogenetic machine-learning approach incorporating linear and geometric morphometric analyses (including >11,000 original linear measurements) to characterize osteological correlates of interdigital webbing, soft-tissue flippers, and aquatic habits in amniotes. They find that relative hand length can reconstruct soft-tissue phenotypes and aquatic habits in extinct amniotes with >90% accuracy, enabling a more phylogenetically comprehensive investigation of limb evolution among bona fide aquatic and terrestrial species. This investigation reveals distinct morphometric landscapes for limb evolution in mammals and reptiles and clarifies the aquatic habits of multiple extinct groups with historically ambiguous ecologies. In addition, it debuts a versatile supervised machine-learning approach for reconstructing cryptic phenotypes from fossil material. O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/661573v1_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@38ca68org.highwire.dtl.DTLVardef@708fb4org.highwire.dtl.DTLVardef@1eaa6f6org.highwire.dtl.DTLVardef@7795c6_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIForelimb proportions reliably predict soft-tissue flippers and highly/fully aquatic habits with >90% accuracy across amniotes. C_LIO_LIInterdigital webbing cannot be predicted from the bones alone using previously suggested correlates. C_LIO_LIAll Paleozoic marine reptiles known to date lived at most an amphibious lifestyle, regularly voyaging onto land. C_LIO_LIPhylogenetic Receiver-Operating Characteristic (ROC) analysis effectively reconstructs cryptic phenotypes in extinct species. C_LI

paleontology↗

bioRxiv2025

A novel function for endothelial protease-activated receptors in modulating insulin receptor activity with implications for diabetes

Thrombin, a serine protease with increased activity in diabetics, signals through protease-activated receptors 1 and 4 (PAR1/PAR4) on endothelial cells (ECs). While studying the roles of endothelial PAR1/4 in diabetic pathology, we found that mice with inducible deletion of both receptors on ECs (Par1/4iECko) displayed increased insulin sensitivity and were protected against streptozotocin (STZ)-induced diabetes. Concordantly, we found that cultured primary ECs with PAR1/4 deficiency had increased basal activity/phosphorylation of the insulin receptor (IR) and insulin transcytosis. This elevated IR activity correlated with reduced activity of protein tyrosine phosphatase 1B (PTP1B), which is a negative regulator of IR activity. Lastly, Par1/4iECkomice with additional deletion of one allele of the IR gene demonstrated restoration of diabetic phenotypes after STZ treatment, indicating that these phenotypes are driven by heightened IR activity. These findings establish a novel link between endothelial PAR signaling and IR regulation, underscoring the critical role of ECs in metabolic homeostasis and identifying a potential therapeutic target for diabetes. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/644607v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@4a5d4forg.highwire.dtl.DTLVardef@34012corg.highwire.dtl.DTLVardef@391efeorg.highwire.dtl.DTLVardef@21e3f8_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Targeting endothelial ERG to mitigate vascular regression and neuronal ischemia in retinopathies

Retinopathy of prematurity (ROP) and diabetic retinopathy (DR) are ocular disorders in which a loss of retinal vasculature leads to ischemia followed by a compensatory neovascularization response. In mice, this is modeled using oxygen-induced retinopathy (OIR), whereby neonatal animals are transiently housed under hyperoxic conditions that result in central retina vessel regression and subsequent neovascularization. Using endothelial cell (EC)-specific gene deletion, we found that loss of two ETS-family transcription factors, ERG and FLI1, led to regression of OIR-induced neovascular vessels but failed to improve visual function, suggesting that relevant retinal damage occurs prior to and independently of neovascularization. Turning our attention to the initial stage of OIR, we found that hyperoxia repressed ERG expression in retinal ECs of wild type mice, raising the possibility that oxygen-induced ERG downregulation promotes vessel regression during the initiation of OIR-induced pathology. We therefore developed a murine model of EC-specific ERG overexpression and found it sufficient to prevent hyperoxia-induced vascular regression, neuronal cell death, and neovascularization in the OIR model. Importantly, ERG overexpression also improved visual function in OIR-challenged mice. Moreover, we show that both ERG and FLI1 are downregulated in the retinal vessels of human patients with early stages of DR, suggesting that neovascular disorders of the eye may share common mechanisms underlying pathological retinal capillary regression. Collectively, these data suggest that the regulation of vascular regression by EC-expressed ETS transcription factors may be adapted towards novel therapeutic approaches for the prevention and/or alleviation of ocular neovascular disorders.

pathology↗

bioRxiv2024

Endothelial RIPK3 minimizes organotypic inflammation and vascular permeability in ischemia-reperfusion injury

Recent studies have revealed a link between endothelial receptor-interacting protein kinase 3 (RIPK3) and vascular integrity. During mouse embryonic development, hypoxia can trigger elevated endothelial RIPK3 that contributes to lethal vascular rupture. However, it is unknown whether RIPK3 regulate endothelial barrier function in adult vasculature under hypoxic injury conditions such as ischemia-reperfusion (I/R) injury. Here we performed inducible genetic deletion of endothelial Ripk3 (RipkiECKO) in mice, which led to elevated vascular permeability in the small intestine and multiple distal organs after intestinal I/R injury. Mechanistically, this vascular permeability correlated with increased endothelial secretion of IL-6 and organ-specific expression of VCAM-1 and ICAM-1 adhesion molecules. Circulating monocyte depletion with clodronate liposomes reduced permeability in organs with elevated adhesion molecules, highlighting the contribution of monocyte adhesion and extravasation to RipkiECKO barrier dysfunction. These results elucidate mechanisms by which RIPK3 regulates endothelial inflammation to minimize vascular permeability in I/R injury. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/625188v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1b3ef3forg.highwire.dtl.DTLVardef@201e47org.highwire.dtl.DTLVardef@a402e0org.highwire.dtl.DTLVardef@1b8f5cb_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

Acetaminophen Overdose Reveals Protease-Activated Receptor 4 as a Low-Expressing but Potent Receptor on the Hepatic Endothelium

Background & AimsHepatic endothelial cell (EC) dysfunction and centrilobular hepatocyte necrosis occur with acetaminophen (APAP) overdose. The protease thrombin, which is acutely generated during APAP overdose, can signal through protease-activated receptors 1 and 4 (PAR1/PAR4). PAR1 is a high-affinity thrombin receptor that is known to signal on ECs, whereas PAR4 is a low-affinity thrombin receptor, and evidence for its expression and function on ECs is mixed. This study aims to exploit the high levels of thrombin generated during APAP overdose to determine (1) if hepatic endothelial PAR4 is a functional receptor, and (2) endothelial-specific functions for PAR1 and PAR4 in a high thrombin setting. MethodsWe generated mice with conditional deletion(s) of Par1/Par4 in ECs and overdosed them with APAP. Hepatic vascular permeability, erythrocyte congestion/bleeding, and liver function were assessed following overdose. Additionally, we investigated the expression levels of endothelial PARs and how they influence transcription in APAP-overdosed liver ECs using endothelial Translating Ribosome Affinity Purification followed by next-generation sequencing (TRAPseq). ResultsWe found that mice deficient in high-expressing endothelial Par1 or low-expressing Par4 had equivalent reductions in APAP-induced hepatic vascular instability but no effect on hepatocyte necrosis. Additionally, mice with loss of endothelial Par1 and Par4 had reduced permeability at an earlier time point after APAP overdose when compared to mice singly deficient in either receptor in ECs. We also found that endothelial PAR1--but not PAR4--can regulate transcription in hepatic ECs. ConclusionsLow-expressing PAR4 can react similarly to high-expressing PAR1 in APAP-overdosed hepatic ECs, demonstrating that PAR4 is a potent thrombin receptor. Additionally, these receptors are functionally redundant but act divergently in their expression and ability to influence transcription in hepatic ECs. NOMENCLATUREF2r and F2rl3 are the gene names for PAR1 and PAR4, respectively. For simplicity, we hereafter refer to these genes as Par1 and Par4.

cell biology↗

bioRxiv2023

Epigenetic Regulation of Endothelial Extracellular Matrix Components is Critical for Murine Lung Development

BackgroundThe chromatin remodeling enzymes BRG1 (brahma-related gene 1) and CHD4 (chromodomain helicase DNA binding protein 4) independently regulate transcription of genes critical for vascular development, but their coordinated impact on vessels in late- stage embryos has not been explored. MethodsIn this study we genetically deleted endothelial Brg1 and Chd4 in mixed background mice (Brg1fl/fl;Chd4fl/fl;VE-Cadherin-Cre+), and littermates that were negative for Cre recombinase were used as controls. Perinatal lung tissue was analyzed by immunostaining, immunoblots, and flow cytometry. Quantitative reverse transcription PCR was used to determine gene expression, and chromatin immunoprecipitation revealed gene targets of BRG1 and CHD4 in cultured endothelial cells (ECs). ResultsWe found that Brg1/Chd4 double mutants died soon after birth with small and compact lungs. Despite having normal cellular composition, distal air sacs of the mutant lungs displayed diminished ECM (extracellular matrix) components and TGF{beta} (transforming growth factor beta) signaling, which typically promotes matrix synthesis. Transcripts for collagen- and elastin-related genes and the TGF{beta} ligand Tgfb1 were decreased in mutant lung ECs, but genetic deletion of endothelial Tgfb1 failed to recapitulate the small lungs and ECM defects seen in Brg1/Chd4 mutants. We instead found several ECM genes to be direct targets of BRG1 and CHD4 in cultured ECs. ConclusionsCollectively, our data highlight essential roles for ECs in promoting ECM deposition at late stages of embryonic lung development. Moreover, this endothelial ECM production is epigenetically regulated. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/552718v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@210be1org.highwire.dtl.DTLVardef@192ee2dorg.highwire.dtl.DTLVardef@1530595org.highwire.dtl.DTLVardef@1938529_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIGenetic deletion of the chromatin remodeling enzymes BRG1 and CHD4 in endothelial cells of late-stage mouse embryos (Brg1/Chd4-ECdko) results in small and compact lungs at birth. C_LIO_LIMutant embryos display reduced collagen IV deposition, dysregulated elastin fibers, and diminished TGF{beta}1 in the distal air sacs. C_LIO_LIOur combined in vitro and in vivo analyses indicate that BRG1 and CHD4 epigenetically regulate collagen IV- and elastin-related gene expression in embryonic ECs to promote proper lung development. C_LI

developmental biology↗

bioRxiv2023

Cytokine-Mediated Degradation of the Transcription Factor ERG Impacts the Pulmonary Vascular Response to Systemic Inflammatory Challenge

BackgroundDuring infectious diseases, pro-inflammatory cytokines transiently destabilize interactions between adjacent vascular endothelial cells (ECs) to facilitate the passage of immune molecules and cells into tissues. However, in the lung the resulting vascular hyperpermeability can lead to organ dysfunction. Previous work identified the transcription factor ERG as a master regulator of endothelial homeostasis. Here we investigate whether the sensitivity of pulmonary blood vessels to cytokine-induced destabilization is due to organotypic mechanisms affecting the ability of endothelial ERG to protect lung ECs from inflammatory injury. MethodsCytokine-dependent ubiquitination and proteasomal degradation of ERG was analyzed in cultured Human Umbilical Vein ECs (HUVECs). Systemic administration of TNF or the bacterial cell wall component lipopolysaccharide (LPS) was used to cause a widespread inflammatory challenge in mice; ERG protein levels were assessed by immunoprecipitation, immunoblot, and immunofluorescence. Murine Erg deletion was genetically induced in ECs (Ergfl/fl;Cdh5(PAC)CreERT2), and multiple organs were analyzed by histology, immunostaining, and electron microscopy. ResultsIn vitro, TNF promoted the ubiquitination and degradation of ERG in HUVECs, which was blocked by the proteasomal inhibitor MG132. In vivo, systemic administration of TNF or LPS resulted in a rapid and substantial degradation of ERG within lung ECs, but not ECs of the retina, heart, liver, or kidney. Pulmonary ERG was also downregulated in a murine model of influenza infection. Ergfl/fl;Cdh5(PAC)-CreERT2 mice spontaneously recapitulated aspects of inflammatory challenges, including lung-predominant vascular hyperpermeability, immune cell recruitment, and fibrosis. These phenotypes were associated with a lung-specific decrease in the expression of Tek, a gene target of ERG previously implicated in maintaining pulmonary vascular stability during inflammation. ConclusionsCollectively, our data highlight a unique role for ERG in pulmonary vascular function. We propose that cytokine-induced ERG degradation and subsequent transcriptional changes in lung ECs play critical roles in the destabilization of pulmonary blood vessels during infectious diseases.

cell biology↗