Biology subjects

Fields, T. A.

Publications and source records attributed to Fields, T. A..

8 recordsLinked to original sources

bioRxiv2026

Differential Protection against Acetaminophen-induced Liver and Kidney Injury by N-Acetylcysteine and Fomepizole in Female Mice

Acetaminophen (APAP) overdose is the leading cause of acute liver failure and is frequently complicated by acute kidney injury (AKI), which worsens clinical outcomes. Although N-acetylcysteine (NAC) effectively attenuates APAP-induced hepatotoxicity by restoring hepatic glutathione (GSH), its efficacy against AKI remains limited, suggesting distinct mechanisms of renal injury. We investigated the role of GSH homeostasis and potential beneficial effects of NAC and Fomepizole (4-methylpyrazole) in APAP-induced liver and kidney injury using female C57BL/6J mice, which naturally lack renal CYP2E1 expression and therefore provide a unique model to examine nephrotoxicity independent of renal CYP2E1-mediated bioactivation. Female mice received APAP (300 or 600 mg/kg) with or without buthionine sulfoximine (BSO, 50 mg/kg) to inhibit GSH synthesis, NAC (500 mg/kg) to promote GSH recovery, or Fomepizole (50 mg/kg) to inhibit CYP2E1-mediated bioactivation. APAP overdose caused severe hepatotoxicity, whereas kidney injury remained minimal during the first 24 h. Although BSO markedly enhanced hepatic GSH depletion and liver injury, it did not significantly worsen renal dysfunction or tubular injury. In contrast, NAC substantially reduced liver injury and improved survival after severe APAP overdose; yet renal dysfunction progressed by 48 h, accompanied by tubular vacuolation, increased KIM-1 and osteopontin expression, and tubular cell death. Fomepizole substantially protected both organs from injury. These findings demonstrate that delayed APAP-induced AKI can develop independent of the severity of liver injury, even with effective NAC-mediated hepatoprotection. On the other hand, Fomepizole protects against AKI in female mice by a CYP2E1-independent mechanism.

pharmacology and toxicology↗

bioRxiv2026

Differentiating Hepatic and Renal Toxicity Reveals CYP-Independent Mechanisms of Acetaminophen-Induced Acute Kidney Injury

Acetaminophen (APAP) overdose is the leading cause of acute liver failure (ALF), with acute kidney injury (AKI) contributing substantially to morbidity and mortality in those patients. To determine whether APAP-induced AKI depends on hepatic CYP2E1-mediated bioactivation, we used CYP2E1^flox/flox^ mice treated with AAV8-TBG-Cre to selectively delete hepatic CYP2E1 while preserving renal metabolism. Male and female mice received APAP (600 mg/kg) and were evaluated up to 48 hours for liver and kidney injury. Liver-specific CYP2E1 deletion reduced APAP hepatotoxicity, confirming the absence of hepatic NAPQI formation. Despite this protection, both male and female mice treated with AAV8-TBG-Cre and APAP developed progressive renal injury, with marked increases in blood urea nitrogen (BUN) and creatinine, tubular vacuolation, and strong induction of KIM-1 and osteopontin, along with apoptotic cell death at 48 hours. Notably, female mice, lacking renal CYP2E1 and displaying no detectable renal protein adducts, still progressed to AKI, demonstrating that kidney injury can occur through CYP-independent mechanisms. Given that APAP-induced AKI is a delayed injury, we further considered p-aminophenol (PAP), a deacetylation product of APAP, as a potential CYP-independent contributor. These findings support the concept that non-CYP pathways, including PAP formation, may contribute to kidney injury during the later phase of toxicity, although this pathway likely represents only one component of a multifactorial injury process. Together, these results demonstrate that APAP-induced AKI is a kidney-intrinsic process that can develop independently of both hepatic and renal CYP2E1 activity, emphasizing the need for kidney-specific therapeutic strategies for preventing APAP-induced renal injury.

pharmacology and toxicology↗

bioRxiv2026

Anti-Polyamine Therapy Restrains Kidney Cyst Growth in an Orthologous Mouse Model of Autosomal Dominant Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common monogenic kidney disease worldwide. Tolvaptan is currently the only approved intervention to slow kidney cyst growth, but its indication is limited to rapidly progressing ADPKD and use compromises quality of life. Hence, new therapeutic options are of high clinical importance. Metabolic dysregulation is a hallmark of kidney cyst growth, including reprogramming of arginine metabolism and polyamine production. Sustained increases in polyamine synthesis drive pathological epithelial cell proliferation, tissue remodeling, and activation of M2-like macrophages, all known drivers of PKD. Difluoromethylornithine (DFMO) is an FDA approved irreversible inhibitor of ornithine decarboxylase (ODC1), the rate limiting enzyme in the arginine-polyamine pathway. Here, we treated C57Bl6/J p.R3277C (Pkd1RC/RC) mice for five months with DFMO-supplemented drinking water to test if DFMO treatment can slow kidney cyst growth in an orthologous model of ADPKD that mimics the disease pathophysiology seen in patients. At study end, Pkd1RC/RC mice treated with DFMO presented with significantly reduced percent kidney weight normalized to body weight as well as kidney cystic index and cyst number compared to control. Kidney RNA-seq analyses revealed correction of many genes and pathways perturbed in PKD post DFMO treatment, as well as overall heathier kidney cellular architecture as inferred by RNAseq-base cell type deconvolution. Our data highlight significant potential to repurpose DFMO for the treatment of patients with ADPKD and investigate the role of polyamines in modulating epithelial as well as myeloid cell fate in the setting of PKD.

pharmacology and toxicology↗

bioRxiv2023

Notch3 deletion regulates HIV-1 gene expression and systemic inflammation to ameliorate chronic kidney disease

Antiretroviral therapy (ART) has decreased HIV-1 associated morbidity. However, despite ART, immune cells remain latently infected and slowly release viral proteins, leading to chronic inflammation and HIV-1 associated comorbidities. New strategies are needed to target viral proteins and inflammation. We found activation of Notch3 in several renal cells of the HIV-1 mouse model (HIV-Tg26) and in patients with HIV associated Nephropathy. We hypothesized that targeting Notch3 activation constitutes an effective therapy for HIV-related chronic kidney diseases (HIV-CKD). We generated HIV-Tg26 mice with Notch3 knocked out (Tg-N3KO). Compared to HIV-Tg26 mice at 3 months, HIV-Tg-N3KO mice showed a marked reduction in renal injury, skin lesions and mortality rate. Bulk RNA sequencing revealed that N3KO not only reduced renal infiltrating cells but significantly reduced the expression of HIV genes. Moreover, Notch3 activated the HIV-promoter and induction of HIV-1 resulted in increased Notch3 activation indicating a feedback mechanism. Further, bone marrow derived macrophages (BMDMs) from HIV-Tg26 mice showed activation of Notch3 indicating systemic effects. Consistent with that, systemic levels of TNF-, MCP-1 and other inflammatory chemokines and cytokines were reduced in Tg-N3KO mice. Thus, Notch3 inhibition/deletion has a dual therapeutic effect in HIV-CKD and may extend to other HIV-related pathologies.

molecular biology↗

bioRxiv2020

DOT1L primarily acts as a transcriptional repressor in hematopoietic progenitor cells

DOT1L is essential for early hematopoiesis but the precise mechanisms remain largely unclear. The only known function of DOT1L is histone H3 lysine 79 (H3K79) methylation. We generated two mouse models; a Dot1L-knockout (Dot1L-KO), and another possessing a point mutation in its methyltransferase domain (Dot1L-MM) to determine the role of its catalytic activity during early hematopoiesis. We observed that Dot1L-KO embryos suffered from severe anemia, while Dot1L-MM embryos showed minimal to no anemia. However, ex vivo culture of Dot1L-MM hematopoietic progenitors (HPCs) exhibited defective development of myeloid and mixed progenitors. DOT1L is a well-recognized, cell-type specific epigenetic regulator of gene expression. To elucidate the mechanisms underlying such diverse hematopoietic properties of Dot1L-KO and Dot1L-MM HPCs, we examined their whole transcriptomes. Extensively self-renewing erythroblast (ESRE) cultures were established using yolk sac (YS) cells collected on embryonic day 10.5 (E10.5). Dot1l-KO and Dot1l-MM cells expanded significantly less than the wildtype cells and showed slower progression through the cell cycle. Total RNA extracted from the wildtype and Dot1l-mutant ESRE cells were subjected to RNA-seq analyses. We observed that the majority (~82%) of the differentially expressed genes (DEGs) were upregulated in both of the Dot1L-mutants, which suggests that DOT1L predominantly acts as a transcriptional repressor in HPCs. We also observed that about ~40% of the DEGs were unique to either of the mutant group, suggesting that DOT1L possesses both methyltransferase domain-dependent and -independent functions. We further analyzed Gene Ontology and signaling pathways relevant to the DEGs common to both mutant groups and those that were unique to either group. Among the common DEGs, we observed upregulation of CDK inhibitors, which explains the cell cycle arrest in both of the Dot1L-mutant progenitors.

developmental biology↗

bioRxiv2020

DOT1L methyltransferase regulates the calcium influx in erythroid progenitor cells in response to erythropoietin

Erythropoietin (EPO) signaling plays a vital role in erythropoiesis by regulating proliferation and lineage-specific differentiation of hematopoietic progenitor cells. An important downstream response of EPO signaling is calcium influx, which is regulated by transient receptor potential channel (TRPC) proteins, particularly TRPC2 and TRPC6. While EPO induces Ca2+influx through TRPC2, TRPC6 inhibits the function of TRPC2. Thus, interactions between TRPC2 and TRPC6 regulate the rate of Ca2+influx in EPO-induced erythropoiesis. In this study, we observed that the expression of TRPC6 in c-KIT positive erythroid progenitor cells is regulated by DOT1L. DOT1L is a methyltransferase that plays an important role in many biological processes during embryonic development, including early erythropoiesis. We previously reported that Dot1L knockout (Dot1L-KO) hematopoietic progenitors in the yolk sac failed to develop properly, which resulted in lethal anemia. In this study, we have detected a marked downregulation of Trpc6 gene expression in Dot1L-KO progenitor cells in the yolk sac compared to wildtype. However, the expression of Trpc2, the positive regulator of Ca2+influx, remained unchanged. The promoter and the proximal region of the Trpc6 gene loci exhibited an enrichment of H3K79 methylation, which is mediated solely by DOT1L. As the loss of DOT1L affects the expression of TRPC6, which inhibits Ca2+influx by TRPC2, Dot1L-KO progenitor cells in the yolk sac exhibit accelerated and sustained high levels of Ca2+influx. Such heightened Ca2+ levels might have detrimental effects on the development of hematopoietic progenitor cells in response to erythropoietin.

developmental biology↗

bioRxiv2020

The Role of DOT1L Methyltransferase Activity in Fetal Hematopoiesis

Early mammalian erythropoiesis requires the DOT1L methyltransferase. We demonstrated that loss of DOT1L in mutant mice resulted in lethal anemia during midgestation. The molecular mechanisms by which DOT1L regulates embryonic erythropoiesis have not yet been elucidated. In this study, a methyltransferase mutant mouse line (Dot1L-MM) was generated to determine whether the methyltransferase activity of DOT1L is essential for erythropoiesis. Dot1L-MM mice displayed embryonic lethality between embryonic days 10.5 and 13.5, similar to Dot1lL knockout (Dot1L-KO) mice. However, when examined at E10.5, unlike the Dot1L-KO, Dot1L-MM embryos did not exhibit evidence of anemia. In ex vivo hematopoietic differentiation cultures, Dot1L-KO and Dot1L-MM yolk sac (YS) cells both formed reduced numbers of myeloid, and mixed hematopoietic colonies. Erythroid colonies were able to be formed in numbers equal to wildtype embryos. Extensively self-renewing erythroblast (ESRE) cultures were established using YS cells from E10.5 embryos. Dot1L-KO and Dot1L-MM cells expanded significantly less than wild-type cells and exhibited increased cell death. Strikingly, Dot1L-KO and Dot1L-MM cells of YS origin exhibited profound genomic instability, implicating DOT1L methyltransferase activity in maintenance of the genome as well as viability of hematopoietic progenitors. Our results indicate that the methyltransferase activity of DOT1L plays an important role early murine hematopoiesis.

developmental biology↗

bioRxiv2020

Wireless Programmable Recording and Stimulation of Deep Brain Activity in Freely Moving Humans

Current implantable devices that allow for recording and stimulation of brain activity in humans are not inherently designed for research and thus lack programmable control and integration with wearable sensors. We developed a platform that enables wireless and programmable intracranial electroencephalographic recording and deep brain stimulation integrated with wearable technologies. This methodology, when used in freely moving humans with implanted neural devices, can provide an ecologically valid environment conducive to elucidating the neural mechanisms underlying naturalistic behaviors and developing viable therapies for neurologic and psychiatric disorders.

neuroscience↗