Biology subjects

Watts, D.

Publications and source records attributed to Watts, D..

6 recordsLinked to original sources

bioRxiv2025

First study of an aye-aye (Daubentonia madagascariensis) mother's anxiety behaviors peripartum

Anxiety is a negative psychological state induced by stress triggers that can be examined in animals which exhibit repetitive, self-directed behaviors. Primate mothers face anxiety due to birthing, infant health, and social relations. In this study, a mother aye-aye (Daubentonia madagascariensis) was observed to assess anxiety behaviors. It was hypothesized that the behaviors would change over time. With Duke IACUC approval, Pelco IMM12027-1S cameras were placed in the Duke Lemur Center (DLC) aye-aye mothers enclosure to record her activity. Over three days peripartum, full 24-hour footage and continuous focal animal sampling were used to note the time, duration, and type of repetitive scratching, grooming, etc. Data were then analyzed using Chi-square, Fishers Exact, and Kruskal Wallis tests. The results showed that the day before birth, the mother repeatedly constructed and deconstructed nests eight times more than engaging in any other behavior (n=212x), while on the day of birth, the mother scratched (n=87x) and groomed (n=60x) herself a lot. The day after birth, the mother was hyper-vigilant (n=32x). Thus, the hypothesis was supported as the mother exhibited signs of anxiety by engaging in different anxiety-related behaviors over the three-day period. While limitations such as a small sample size (n=1) and possible abnormal parturition behavior are evident, this study is the first to examine maternal anxiety in aye-ayes. The results can help husbandry staff create more comfortable environments for the rare and difficult-to-see captive aye-ayes.

animal behavior and cognition↗

bioRxiv2025

Hypoxia Inducible Factor 1α-driven steroidogenesis impacts systemic hematopoiesis

Glucocorticoids regulate hematopoiesis, but how chronic elevation of endogenous glucocorticoid production affects hematopoietic stem cell (HSC) function and immune cell development remains incompletely understood. Using an adrenocortical cell-specific HIF1 (Hypoxia inducible Factor-1)-deficient mouse model (P2H1Ad.Cortex) resulting in elevated glucocorticoid (GC) levels, we here demonstrate that sustained GC exposure promotes hematopoietic stem and progenitor cell (HSPC) expansion while shifting HSCs toward a more quiescent and metabolically restrained state. Functionally, these HSCs exhibited enhanced regenerative potential, as evidenced by superior donor chimerism in transplantation assays. In addition, we observed a striking increase in myeloid progenitors, as well as in their progeny (monocytes and granulocytes). Conversely, B-cell differentiation in the bone marrow was severely impaired, with a strong block at the pre-pro-B cell stage. To determine whether these phenotypes were driven by glucocorticoid receptor (GR) signaling, we performed transplantation experiments using GR-deficient or WT control bone marrow into P2H1Ad.Cortex or WT littermate recipients. This approach decisively demonstrated that both the increase in myeloid cells and the block in B-cell differentiation were GR-dependent, confirming that GC-GR signaling plays a pivotal role in shaping hematopoiesis. Taken together, our findings clearly suggest a direct role for chronic glucocorticoid exposure in regulating HSC function, lineage differentiation, and stress hematopoiesis. The mouse model of adrenocortical cell-specific HIF1 deficiency provides a valuable tool to study the long-term effects of elevated glucocorticoid levels on hematopoietic regulation and may provide further insight into hematologic disorders associated with chronic therapeutic glucocorticoid administration. Article Summary- Our study aimed to elucidate how chronic elevation of glucocorticoids impacts hematopoietic stem cell function and immune cell development using an adrenocortical cell-specific HIF1-deficient mouse model. - The main conclusion is that sustained glucocorticoid exposure, through glucocorticoid receptor signaling, promotes hematopoietic stem and progenitor cell expansion with enhanced regenerative potential while skewing lineage differentiation toward myeloid expansion and impeding B-cell development.

immunology↗

bioRxiv2024

HIF1α controls steroidogenesis under acute hypoxic stress

BackgroundHypoxia is a critical physiological and pathological condition known to influence various cellular processes, including steroidogenesis. While previous studies, including our own, have highlighted the regulatory effects of Hypoxia-Inducible Factor 1 (HIF1) on steroid production, the specific molecular mechanisms remain poorly understood. This study investigates the role of hypoxia and HIF1 in steroid biosynthesis across multiple experimental models during acute exposure to low oxygen levels. MethodsTo assess the extent to which acute hypoxia modulates steroidogenesis, we employed several approaches, including the Y1 adrenocortical cell line, an ex vivo adrenal gland explant model, and a conditional HIF1-deficient mouse line in the adrenal cortex. We focused on various regulatory patterns that may critically suppress steroidogenesis. ResultsIn Y1 cells and adrenal gland explants, hypoxia induced the upregulation of specific microRNAs, leading to the suppression of mRNA levels of key steroidogenic enzymes and reduced steroid hormone production. The hypoxia/HIF1-dependent induction of these microRNAs and the consequent modulation of steroid production were confirmed in vivo. Notably, using our conditional HIF1-deficient mouse line, we found that the increase in miRNA expression under hypoxic conditions is directly dependent on HIF1. Furthermore, the regulation of steroidogenic enzymes (e.g., StAR and Cyp11a1) and steroid production occurred at the level of protein translation, revealing an unexpected layer of control under hypoxic conditions in vivo. ConclusionsThese findings elucidate the molecular mechanisms underlying acute hypoxia-induced changes in steroid biosynthesis and may also be useful in developing new strategies for various steroid hormone pathologies.

molecular biology↗

bioRxiv2024

Endoglin regulates the integrity of the bone marrow vasculature

Endoglin (Eng) is an accessory receptor for transforming growth factor-{beta} (TGF-{beta}) that is critical for maintaining vascular integrity. Mutations in Eng cause hereditary hemorrhagic telangiectasia (HHT), resulting in arteriovenous malformations (AVMs) and blood abnormalities. Despite the known association between Eng deficiency and AVMs, the underlying mechanisms are unclear. In addition, the role of the bone marrow (BM), a major source of immune and blood cells, in endothelial Eng (EC-Eng) deficiency is unexplored. We show that BM blood vessels conditionally deficient in Eng (cKO) undergo a structured remodeling process over four weeks, with distinct proliferative and resolution phases. These phases involve angiogenic set points, the involvement of integrins, and the modulation of vascular integrity. In addition, we observe changes in hematopoietic stem and progenitor cells (HSPC) and circulating granulocytes, along with reduced red blood cells and platelets due to splenic sequestration. Using a conditional heterozygous EC-Eng deficient mouse model, reflecting the genetics of HHT patients, we identify vascular changes similar to those in the cKO model. Taken together, using multiple in vivo approaches, we suggest that reduced Eng expression in the endothelium drives significant BM vascular remodeling, sharing mechanisms with early vascular processes associated with AVM formation. Explanation of NoveltyOur findings reveal that BM blood vessels deficient in endoglin undergo an orchestrated remodeling process with distinct proliferative and resolution phases over several weeks. We identify specific angiogenic set points and profound alterations in vascular integrity, along with hematopoietic changes starting at the level of hematopoietic stem and progenitor cells. These findings advance our understanding of the role of Eng in vascular remodeling and may provide novel therapeutic targets for HHT. Key PointsO_LIConditional EC-Eng deficiency leads to vascular remodeling in the BM of mice in a temporally orchestrated manner. C_LIO_LIEC-Eng facilitates vascular integrity, hematopoietic homeostasis, and immune cell mobilization. C_LI

molecular biology↗

bioRxiv2020

Hypoxia pathway proteins regulate the synthesis and release of epinephrine in the mouse adrenal gland

The adrenal gland and its hormones regulate numerous fundamental biological processes; however, the impact of hypoxia signalling on its function remains scarcely understood. Here, we reveal that deficiency of HIF (Hypoxia Inducible Factors) prolyl hydroxylase domain protein-2 (PHD2) in the adrenal medulla of mice results in HIF2-mediated reduction in phenylethanolamine N-methyltransferase (PNMT) expression, and consequent reduction in epinephrine synthesis. Concomitant loss of PHD2 in renal erythropoietin (EPO) producing cells stimulated HIF2-driven EPO overproduction, excessive RBC formation (erythrocytosis) and systemic hypoglycaemia. Using mouse lines displaying only EPO-induced erythrocytosis or anaemia, we show that hypo- or hyperglycaemia is necessary and sufficient to respectively enhance or reduce exocytosis of epinephrine from the adrenal gland. Based on these results, we propose that the PHD2-HIF2 axis in the adrenal medulla and beyond regulates both synthesis and release of catecholamines, especially epinephrine. Our findings are also of great significance in view of the small molecule PHD inhibitors being tested in phase III global clinical development trials for use in renal anaemia patients.

molecular biology↗

bioRxiv2018

Schlafen 11 Restricts Flavivirus Replication

Schlafen 11 (Slfn11) is a ubiquitously expressed interferon stimulating gene (ISG) that controls synthesis of proteins by regulating tRNA abundance. Likely through this mechanism, Slfn11 has previously been shown to impair human immunodeficiency virus 1 (HIV-1) infection and the expression of codon-biased open reading frames. Because replication of positive-sense single-stranded RNA [(+)ssRNA viruses] requires the immediate translation of the incoming viral genome whereas negative sense, single stranded [(-)ssRNA] viruses carry at infection an RNA replicase that makes multiple translation competent copies of the incoming viral genome, we reasoned that (+)ssRNA viruses will be more sensitive to the effect of Slfn11 on protein synthesis than (-)ssRNA viruses. To evaluate this hypothesis, we tested the effects of Slfn11 on the replication of a panel of ssRNA viruses in the human glioblastoma cell line A172, which naturally expresses Slfn11. Depletion of Slfn11 in this cell line significantly increased the replication of (+)ssRNA viruses from the Flavivirus family, including West Nile (WNV), dengue (DENV), and Zika virus (ZIKV) but had no significant effect on the replication of the (-)ssRNA viruses vesicular stomatitis (VSV, Rhabdoviridae family) and Rift Valley fever (RVFV, Phenuiviridae family). Despite that WNV titers in Slfn11-deficient cells were almost 100-fold higher than in cells expressing this protein; they produced approximately two-fold less viral particles, as determined by PCR-based quantification of virion-associated WNV RNA in the cell culture supernatant. These data indicated that Slfn11 impairs WNV fitness but does not affect other steps of the viral life cycle including entry, viral RNA replication and translation, and budding. Similarly to the proposed anti-HIV-1 mechanism of Slfn11, this protein prevented WNV-induced down-regulation of a subset of tRNAs implicated in the translation of 19% of the viral polyprotein. Importantly, we provided evidence suggesting that the broad anti-viral activity of Slfn11 requires other cellular proteins, since overexpression of Slfn11 in cells that naturally lack the expression of this protein, did not impair WNV or HIV-1 infection. In summary, this study demonstrates that Slfn11 restricts flaviviruses replication by impairing viral fitness.\n\nAUTHOR SUMMARYThe host targets mechanisms that viruses have evolved to optimize replication. We provide evidence that the cellular protein Schlafen 11 (Slf11) impairs replication of flaviviruses, including West Nile (WNV), dengue (DENV), and Zika virus (ZIKV). However, replication of single-stranded, negative RNA viruses was not affected. Specifically, Slf11 decreases the fitness of WNV potentially by preventing virus-induced modifications of the host tRNA repertoire that could lead to enhanced viral protein folding. Furthermore, we demonstrated that Slf11 is not the limiting factor of this novel broad anti-viral pathway.

microbiology↗