Biology subjects

Pritchard, M. T.

Publications and source records attributed to Pritchard, M. T..

4 recordsLinked to original sources

bioRxiv2025

Targeting Ogt in ADPKD mitigates metabolic reprogramming and renal cystogenesis, extending survival

Aberrant cell metabolism drives autosomal dominant polycystic kidney disease (ADPKD). O-GlcNAcylation, a metabolically regulated post-translational modification, is elevated in ADPKD kidneys. Using rapidly and slowly progressive ADPKD mouse models, we demonstrate that deleting O-GlcNAc transferase (Ogt) reduces renal cystogenesis and extends survival in a rapidly progressive model from postnatal day 21 to over a year. Pharmacological OGT inhibition similarly reduced cyst formation of patient-derived renal epithelial cells in vitro. In Pkd1 conditional knockout kidneys, Ogt deletion maintained phosphorylated AMPK and mitochondrial respiratory chain complex levels, preserving cellular energy sensing and production. Further, metabolomic analysis revealed normalization of glycolysis and of the hexosamine and hyaluronic acid biosynthesis pathways. In contrast, dysregulation of these pathways in Pkd1 conditional knockout kidneys culminated in increased tricarboxylic acid cycle entry, increased O-GlcNAc, and increased hyaluronic acid in the extracellular matrix, respectively. These findings identify Ogt as a central metabolic regulator and therapeutic target, linking metabolism to intracellular and extracellular mechanisms of cyst formation.

cell biology↗

bioRxiv2024

Multinucleated giant cells are hallmarks of ovarian aging with unique immune and degradation-associated molecular signatures

The ovary is one of the first organs to exhibit signs of aging, characterized by reduced tissue function, chronic inflammation, and fibrosis. Multinucleated giant cells (MNGCs), formed by macrophage fusion, typically occur in chronic immune pathologies, including infectious and non-infectious granulomas and the foreign body response1, but are also observed in the aging ovary2-4. The function and consequence of ovarian MNGCs remain unknown as their biological activity is highly context-dependent, and their large size has limited their isolation and analysis through technologies such as single-cell RNA sequencing. In this study, we define ovarian MNGCs through a deep analysis of their presence across age and species using advanced imaging technologies as well as their unique transcriptome using laser capture microdissection. MNGCs form complex interconnected networks that increase with age in both mouse and nonhuman primate ovaries. MNGCs are characterized by high Gpnmb expression, a putative marker of ovarian and non-ovarian MNGCs5,6. Pathway analysis highlighted functions in apoptotic cell clearance, lipid metabolism, proteolysis, immune processes, and increased oxidative phosphorylation and antioxidant activity. Thus, MNGCs have signatures related to degradative processes, immune function, and high metabolic activity. These processes were enriched in MNGCs compared to primary ovarian macrophages, suggesting discrete functionality. MNGCs express CD4 and colocalize with T-cells, which were enriched in regions of MNGCs, indicative of a close interaction between these immune cell types. These findings implicate MNGCs in modulation of the ovarian immune landscape during aging given their high penetrance and unique molecular signature that supports degradative and immune functions.

cell biology↗

bioRxiv2024

Self-organizing ovarian somatic organoids preserve cellular heterogeneity and reveal cellular contributions to ovarian aging

Ovarian somatic cells are essential for reproductive function, but no existing ex vivo models recapitulate the cellular heterogeneity or interactions within this compartment. We engineered a novel ovarian somatic organoid model by culturing a stroma-enriched fraction of mouse ovaries in scaffold-free agarose micromolds. Ovarian somatic organoids self-organized, maintained diverse cell populations, produced extracellular matrix, and secreted hormones. Organoids generated from reproductively old mice exhibited reduced aggregation and growth compared to young counterparts, as well as differences in cellular composition. Interestingly, matrix fibroblasts from old mice demonstrated upregulation of pathways associated with the actin cytoskeleton and downregulation of cell adhesion pathways, indicative of increased cellular stiffness which may impair organoid aggregation. Cellular morphology, which is regulated by the cytoskeleton, significantly changed with age and in response to actin depolymerization. Moreover, actin depolymerization rescued age-associated organoid aggregation deficiency. Overall, ovarian somatic organoids have advanced fundamental knowledge of cellular contributions to ovarian aging.

cell biology↗

bioRxiv2023

Global Transcriptomics of Congenital Hepatic Fibrosis in Autosomal Recessive Polycystic Kidney Disease using PCK rats

Congenital hepatic fibrosis / Autosomal recessive polycystic kidney disease (CHF/ARPKD) is an inherited neonatal disease induced by mutations in the PKHD1 gene and characterized by cysts, and robust pericystic fibrosis in liver and kidney. The PCK rat is an excellent animal model which carries a Pkhd1 mutation and exhibits similar pathophysiology. We performed RNA-Seq analysis on liver samples from PCK rats over a time course of postnatal day (PND) 15, 20, 30, and 90 using age-matched Sprague-Dawley (SD) rats as controls to characterize molecular mechanisms of CHF/ARPKD pathogenesis. A comprehensive differential gene expression (DEG) analysis identified 1298 DEGs between PCK and SD rats. The genes overexpressed in the PCK rats at PND 30 and 90 were involved cell migration (e.g. Lamc2, Tgfb2, and Plet1), cell adhesion (e.g. Spp1, Adgrg1, and Cd44), and wound healing (e.g. Plat, Celsr1, Tpm1). Connective tissue growth factor (Ctgf) and platelet-derived growth factor (Pdgfb), two genes associated with fibrosis, were upregulated in PCK rats at all time-points. Genes associated with MHC class I molecules (e.g. RT1-A2) or involved in ribosome assembly (e.g. Pes1) were significantly downregulated in PCK rats. Upstream regulator analysis showed activation of proteins involved tissue growth (MTPN) and inflammation (STAT family members) and chromatin remodeling (BRG1), and inhibition of proteins involved in hepatic differentiation (HNF4) and reduction of fibrosis (SMAD7). The increase in mRNAs of four top upregulated genes including Reg3b, Aoc1, Tm4sf20, and Cdx2 was confirmed at the protein level using immunohistochemistry. In conclusion, these studies indicate that a combination of increased inflammation, cell migration and wound healing, and inhibition of hepatic function, decreased antifibrotic gene expression are the major underlying pathogenic mechanisms in CHF/ARPKD.

pathology↗