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Now showing 1 - 10 of 321
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    mRNA cap-binding protein eIF4E1 is a novel regulator of Toxoplasma gondii latency
    (bioRxiv, 2023-10-09) Holmes, Michael J.; Bastos, Matheus S.; Dey, Vishakha; Severo, Vanessa; Wek, Ronald C.; Sullivan, William J., Jr.; Pharmacology and Toxicology, School of Medicine
    The protozoan parasite Toxoplasma gondii causes serious opportunistic disease due to its ability to persist in patients as latent tissue cysts. The molecular mechanisms coordinating conversion between proliferative parasites (tachyzoites) and dormant cysts (bradyzoites) are not fully understood. We previously showed that phosphorylation of eIF2α accompanies bradyzoite formation, suggesting that this clinically relevant process involves regulation of mRNA translation. In this study, we investigated the composition and role of eIF4F multi-subunit complexes in translational control. Using CLIPseq, we find that the cap-binding subunit, eIF4E1, localizes to the 5’-end of all tachyzoite mRNAs, many of which show evidence of stemming from heterogenous transcriptional start sites. We further show that eIF4E1 operates as the predominant cap-binding protein in two distinct eIF4F complexes. Using genetic and pharmacological approaches, we found that eIF4E1 deficiency triggers efficient spontaneous formation of bradyzoites without stress induction. Consistent with this result, we also show that stress-induced bradyzoites exhibit reduced eIF4E1 expression. Overall, our findings establish a novel role for eIF4F in translational control required for parasite latency and microbial persistence.
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    Genetic and pharmacologic alterations of claudin9 levels suffice to induce functional and mature inner hair cells
    (bioRxiv, 2023-10-10) Chen, Yingying; Lee, Jeong Han; Li, Jin; Park, Seojin; Perez Flores, Maria C.; Peguero, Braulio; Kersigo, Jennifer; Kang, Mincheol; Choi, Jinsil; Levine, Lauren; Gratton, Michael Anne; Fritzsch, Bernd; Yamoah, Ebenezer N.; Pharmacology and Toxicology, School of Medicine
    Hearing loss is the most common form of sensory deficit. It occurs predominantly due to hair cell (HC) loss. Mammalian HCs are terminally differentiated by birth, making HC loss incurable. Here, we show the pharmacogenetic downregulation of Cldn9, a tight junction protein, generates robust supernumerary inner HCs (IHCs) in mice. The putative ectopic IHCs have functional and synaptic features akin to typical IHCs and were surprisingly and remarkably preserved for at least fifteen months >50% of the mouse's life cycle. In vivo, Cldn9 knockdown using shRNA on postnatal days (P) P1-7 yielded analogous functional putative ectopic IHCs that were equally durably conserved. The findings suggest that Cldn9 levels coordinate embryonic and postnatal HC differentiation, making it a viable target for altering IHC development pre- and post-terminal differentiation.
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    Critical Role of Novel O-GlcNAcylation of S550 and S551 on the p65 Subunit of NF-κB in Pancreatic Cancer
    (MDPI, 2023-09-27) Motolani, Aishat; Martin, Matthew; Wang, Benlian; Jiang, Guanglong; Alipourgivi, Faranak; Huang, Xiumei; Safa, Ahmad; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
    Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a mere 5-year survival of ~10%. This highlights the urgent need for innovative treatment options for PDAC patients. The nuclear factor κB (NF-κB) is a crucial transcription factor that is constitutively activated in PDAC. It mediates the transcription of oncogenic and inflammatory genes that facilitate multiple PDAC phenotypes. Thus, a better understanding of the mechanistic underpinnings of NF-κB activation holds great promise for PDAC diagnosis and effective therapeutics. Here, we report a novel finding that the p65 subunit of NF-κB is O-GlcNAcylated at serine 550 and 551 upon NF-κB activation. Importantly, the overexpression of either serine-to-alanine (S-A) single mutant (S550A or S551A) or double mutant (S550A/S551A) of p65 in PDAC cells impaired NF-κB nuclear translocation, p65 phosphorylation, and transcriptional activity, independent of IκBα degradation. Moreover, the p65 mutants downregulate a category of NF-κB-target genes, which play a role in perpetuating major cancer hallmarks. We further show that overexpression of the p65 mutants inhibited cellular proliferation, migration, and anchorage-independent growth of PDAC cells compared to WT-p65. Collectively, we discovered novel serine sites of p65 O-GlcNAcylation that drive NF-κB activation and PDAC phenotypes, thus opening new avenues by inhibiting the NF-κB O-GlcNAcylation enzyme, O-GlcNAc transferase (OGT), for PDAC treatment in the future.
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    KDM2A Deficiency in the Liver Promotes Abnormal Liver Function and Potential Liver Damage
    (MDPI, 2023-09-27) Martin, Matthew; Motolani, Aishat; Kim, Hyeong-Geug; Collins, Amy M.; Alipourgivi, Faranak; Jin, Jiamin; Wei, Han; Wood, Barry A.; Ma, Yao-Ying; Dong, X. Charlie; Mirmira, Raghavendra G.; Lu, Tao; Pharmacology and Toxicology, School of Medicine
    Dysregulation of metabolic functions in the liver impacts the development of diabetes and metabolic disorders. Normal liver function can be compromised by increased inflammation via the activation of signaling such as nuclear factor (NF)-κB signaling. Notably, we have previously identified lysine demethylase 2A (KDM2A)—as a critical negative regulator of NF-κB. However, there are no studies demonstrating the effect of KDM2A on liver function. Here, we established a novel liver-specific Kdm2a knockout mouse model to evaluate KDM2A’s role in liver functions. An inducible hepatic deletion of Kdm2a, Alb-Cre-Kdm2afl/fl (Kdm2a KO), was generated by crossing the Kdm2a floxed mice (Kdm2afl/fl) we established with commercial albumin-Cre transgenic mice (B6.Cg-Tg(Alb-cre)21Mgn/J). We show that under a normal diet, Kdm2a KO mice exhibited increased serum alanine aminotransferase (ALT) activity, L-type triglycerides (TG) levels, and liver glycogen levels vs. WT (Kdm2afl/fl) animals. These changes were further enhanced in Kdm2a liver KO mice in high-fat diet (HFD) conditions. We also observed a significant increase in NF-κB target gene expression in Kdm2a liver KO mice under HFD conditions. Similarly, the KO mice exhibited increased immune cell infiltration. Collectively, these data suggest liver-specific KDM2A deficiency may enhance inflammation in the liver, potentially through NF-κB activation, and lead to liver dysfunction. Our study also suggests that the established Kdm2afl/fl mouse model may serve as a powerful tool for studying liver-related metabolic diseases.
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    A transcriptional network required for bradyzoite development in Toxoplasma gondii is dispensable for recrudescent disease
    (Springer Nature, 2023-09-28) Sokol-Borrelli, Sarah L.; Reilly, Sarah M.; Holmes, Michael J.; Orchanian, Stephanie B.; Massmann, Mackenzie D.; Sharp, Katherine G.; Cabo, Leah F.; Alrubaye, Hisham S.; Martorelli Di Genova, Bruno; Lodoen, Melissa B.; Sullivan, William J., Jr.; Boyle, Jon P.; Pharmacology and Toxicology, School of Medicine
    Identification of regulators of Toxoplasma gondii bradyzoite development and cyst formation is the most direct way to address the importance of parasite development in long-term persistence and reactivation of this parasite. Here we show that a T. gondii gene (named Regulator of Cystogenesis 1; ROCY1) is sufficient for T. gondii bradyzoite formation in vitro and in vivo. ROCY1 encodes an RNA binding protein that has a preference for 3' regulatory regions of hundreds of T. gondii transcripts, and its RNA-binding domains are required to mediate bradyzoite development. Female mice infected with ΔROCY1 parasites have reduced (>90%) cyst burden. While viable parasites can be cultivated from brain tissue for up to 6 months post-infection, chronic brain-resident ΔROCY1 parasites have reduced oral infectivity compared to wild type. Despite clear defects in bradyzoite formation and oral infectivity, ΔROCY1 parasites were able to reactivate with similar timing and magnitude as wild type parasites for up to 5 months post-infection. Therefore while ROCY1 is a critical regulator of the bradyzoite developmental pathway, it is not required for parasite reactivation, raising new questions about the persisting life stage responsible for causing recrudescent disease.
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    Covariates of Knowledge, Attitude, Practice, and Burdens among the Caregivers of Hypertensive Patients
    (Hindawi, 2023-08-21) Nath, Sudipta Deb; Chowdhury, Afrin Sultana; Pinky, Susmita Dey; Akter, Kazi Mahmuda; Nourin, Nishat Anjum; Chowdhury, Tonmoy; Fahid, Hossain Ahmed; Sharmin, K. M. Shailah; Rana, Md. Mashud; Alam, Nazmul; Ahsan, Md. Moinul; Mannan, Adnan; Pharmacology and Toxicology, School of Medicine
    Caregivers of hypertensive patients play a significant role in ensuring adequate patient care and lowering the risk of hypertension-related complications. Caregivers are ideal study subjects for identifying gaps in hypertension management. Our study aimed to assess the knowledge, attitude, and practice (KAP) of hypertensive patients' caregivers, to identify their extent of involvement in patients' care, and to assess their care-related attributes. A descriptive cross-sectional study was conducted from August 2020 to February 2021 in the eight largest tertiary care medical college hospitals and all eight divisions of Bangladesh, with 949 caregivers enrolled. Data were collected using a pretested interviewer-administered questionnaire through snowball sampling and analyzed using a one-way ANOVA, independent-sample T-test, and chi-square test. Among the 949 interviewed caregivers, 541 (57.0%) were female, and 479 (50.5%) were aged 18 to 25 years. The percentage scores regarding overall knowledge, attitude, and practice of the caregivers were 54.83 ± 17.95, 47.95 ± 24.05, and 61.26 ± 17.50, respectively. Caregivers' education, history of hypertension, residence, age, relationship with the patient, occupation, and caregiving duration were significantly associated with the KAP scores. In addition, factors such as relationship with the patient, age, educational status, occupation, residence, and caregiving duration/day had significant correlations with all types of burden. Findings of this study suggest the necessity for awareness programs for the caregivers of hypertensive patients to diminish the gap in their KAP and improve their mental and physical health.
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    Disease-associated astrocytes and microglia markers are upregulated in mice fed high fat diet
    (Springer Nature, 2023-08-09) Lin, Li; Basu, Rashmita; Chatterjee, Debolina; Templin, Andrew T.; Flak, Jonathan N.; Johnson, Travis S.; Pharmacology and Toxicology, School of Medicine
    High-fat diet (HFD) is associated with Alzheimer's disease (AD) and type 2 diabetes risk, which share features such as insulin resistance and amylin deposition. We examined gene expression associated with astrocytes and microglia since dysfunction of these cell types is implicated in AD pathogenesis. We hypothesize gene expression changes in disease-associated astrocytes (DAA), disease-associated microglia and human Alzheimer's microglia exist in diabetic and obese individuals before AD development. By analyzing bulk RNA-sequencing (RNA-seq) data generated from brains of mice fed HFD and humans with AD, 11 overlapping AD-associated differentially expressed genes were identified, including Kcnj2, C4b and Ddr1, which are upregulated in response to both HFD and AD. Analysis of single cell RNA-seq (scRNA-seq) data indicated C4b is astrocyte specific. Spatial transcriptomics (ST) revealed C4b colocalizes with Gfad, a known astrocyte marker, and the colocalization of C4b expressing cells with Gad2 expressing cells, i.e., GABAergic neurons, in mouse brain. There also exists a positive correlation between C4b and Gad2 expression in ST indicating a potential interaction between DAA and GABAergic neurons. These findings provide novel links between the pathogenesis of obesity, diabetes and AD and identify C4b as a potential early marker for AD in obese or diabetic individuals.
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    Atlas of Plasmodium falciparum intraerythrocytic development using expansion microscopy
    (eLife Sciences, 2023-12-18) Liffner, Benjamin; Cepeda Diaz, Ana Karla; Blauwkamp, James; Anaguano, David; Frolich, Sonja; Muralidharan, Vasant; Wilson, Danny W.; Dvorin, Jeffrey D.; Absalon, Sabrina; Pharmacology and Toxicology, School of Medicine
    Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample by ~4.5×. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have cataloged 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the outer centriolar plaque and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the outer centriolar plaque until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an association with the outer centriolar plaque during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology.
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    The protein phosphatase PPKL is a key regulator of daughter parasite development in Toxoplasma gondii
    (American Society for Microbiology, 2023-10-25) Yang, Chunlin; Doud, Emma H.; Sampson, Emily; Arrizabalaga, Gustavo; Pharmacology and Toxicology, School of Medicine
    Apicomplexan parasites, including Toxoplasma gondii, encode many plant-like proteins, which play significant roles and present attractive targets for drug development. In this study, we have characterized the plant-like protein phosphatase PPKL, which is unique to the parasite and absent in its mammalian host. We have shown that its localization changes as the parasite divides. In non-dividing parasites, it is present in the cytoplasm, nucleus, and preconoidal region. As the parasite begins division, PPKL is enriched in the preconoidal region and the cortical cytoskeleton of nascent parasites. Later in the division, PPKL is present in the basal complex ring. Conditional knockdown of PPKL showed that it is essential for parasite propagation. Moreover, parasites lacking PPKL exhibit uncoupling of division, with normal DNA duplication but severe defects in forming daughter parasites. While PPKL depletion does not impair the duplication of centrosomes, it affects the stability of cortical microtubules. Both co-immunoprecipitation and proximity labeling identified the kinase DYRK1 as a potential functional partner of PPKL. Complete knockout of DYRK1 causes parasites to exhibit division defects with predominantly asynchronous divisions. Global phosphoproteomics analysis revealed a significant increase in phosphorylation of the microtubule-associated protein SPM1 in PPKL-depleted parasites, suggesting that PPKL regulates cortical microtubules by mediating the phosphorylation state of SPM1. More importantly, the phosphorylation of cell cycle-associated kinase Crk1, a known regulator of daughter cell assembly, is altered in PPKL-depleted parasites. Thus, we propose that PPKL regulates daughter parasite development by influencing the Crk1-dependent signaling pathway. IMPORTANCE: Toxoplasma gondii can cause severe disease in immunocompromised or immunosuppressed patients and during congenital infections. Treating toxoplasmosis presents enormous challenges since the parasite shares many biological processes with its mammalian hosts, which results in significant side effects with current therapies. Consequently, proteins that are essential and unique to the parasite represent favorable targets for drug development. Interestingly, Toxoplasma, like other members of the phylum Apicomplexa, has numerous plant-like proteins, many of which play crucial roles and do not have equivalents in the mammalian host. In this study, we found that the plant-like protein phosphatase PPKL appears to be a key regulator of daughter parasite development. With the depletion of PPKL, the parasite shows severe defects in forming daughter parasites. This study provides novel insights into the understanding of parasite division and offers a new potential target for the development of antiparasitic drugs.
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    Trauma-Informed Care in the Classroom: Our Experience with a Content Warning in a Medical School Course
    (Springer, 2022-04-28) Stout, Julianne; Martin, Angelika I.; Pharmacology and Toxicology, School of Medicine
    Trauma is now recognized as a common human experience that has consequences, including adverse effects on learning outcomes. Principles of trauma-informed care include awareness of the impact of trauma and use of strategies to prevent retraumatization. While well-described in medical and mental health care, these principles have been inconsistently applied in the medical education classroom. Content warnings can be part of a trauma-informed classroom approach that notifies learners about potentially distressing topics, allows individuals to employ self-care, and seeks to resist retraumatization. This article describes our experience integrating a content warning about reproductive topics in a second-year medical school course.