Browsing by Author "Tan, Zhiyong"

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    CCL2/CCR2 signaling elicits itch- and pain-like behavior in a murine model of allergic contact dermatitis
    (Elsevier, 2019) Jiang, Haowu; Cui, Huan; Wang, Tao; Shimada, Steven G.; Sun, Rui; Tan, Zhiyong; Ma, Chao; LaMotte, Robert H.; Pharmacology and Toxicology, School of Medicine
    Spontaneous itch and pain are the most common symptoms in various skin diseases, including allergic contact dermatitis (ACD). The chemokine (C-C motif) ligand 2 (CCL2, also referred to as monocyte chemoattractant protein 1 (MCP-1)) and its receptor CCR2 are involved in the pathophysiology of ACD, but little is known of the role of CCL2/CCR2 for the itch- and pain-behaviors accompanying the murine model of this disorder, termed contact hypersensitivity (CHS). C57BL/6 mice previously sensitized to the hapten, squaric acid dibutyl ester, applied to the abdomen were subsequently challenged twice with the hapten delivered to either the cheek or to the hairy skin of the hind paw resulting in CHS at that site. By 24 h after the 2nd challenge to the hind paw CCL2 and CCR2 mRNA, protein, and signaling activity were upregulated in the dorsal root ganglion (DRG). Calcium imaging and whole-cell current-clamp recordings revealed that CCL2 directly acted on its neuronal receptor, CCR2 to activate a subset of small-diameter, nociceptive-like DRG neurons retrogradely labeled from the CHS site. Intradermal injection of CCL2 into the site of CHS on the cheek evoked site-directed itch- and pain-like behaviors which could be attenuated by prior delivery of an antagonist of CCR2. In contrast, CCL2 failed to elicit either type of behavior in control mice. Results are consistent with the hypothesis that CHS upregulates CCL2/CCR2 signaling in a subpopulation of cutaneous small diameter DRG neurons and that CCL2 can activate these neurons through neuronal CCR2 to elicit itch- and pain-behavior. Targeting the CCL2/CCR2 signaling might be beneficial for the treatment of the itch and pain sensations accompanying ACD in humans.
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    The impact of SBF2 on taxane-induced peripheral neuropathy
    (PLOS, 2022-01-05) Cunningham, Geneva M.; Shen, Fei; Wu, Xi; Cantor, Erica L.; Gardner, Laura; Philips, Santosh; Jiang, Guanglong; Bales, Casey L.; Tan, Zhiyong; Liu, Yunlong; Wan, Jun; Fehrenbacher, Jill C.; Schneider, Bryan P.; Medical and Molecular Genetics, School of Medicine
    Taxane-induced peripheral neuropathy (TIPN) is a devastating survivorship issue for many cancer patients. In addition to its impact on quality of life, this toxicity may lead to dose reductions or treatment discontinuation, adversely impacting survival outcomes and leading to health disparities in African Americans (AA). Our lab has previously identified deleterious mutations in SET-Binding Factor 2 (SBF2) that significantly associated with severe TIPN in AA patients. Here, we demonstrate the impact of SBF2 on taxane-induced neuronal damage using an ex vivo model of SBF2 knockdown of induced pluripotent stem cell-derived sensory neurons. Knockdown of SBF2 exacerbated paclitaxel changes to cell viability and neurite outgrowth while attenuating paclitaxel-induced sodium current inhibition. Our studies identified paclitaxel-induced expression changes specific to mature sensory neurons and revealed candidate genes involved in the exacerbation of paclitaxel-induced phenotypes accompanying SBF2 knockdown. Overall, these findings provide ex vivo support for the impact of SBF2 on the development of TIPN and shed light on the potential pathways involved.
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    Passage number affects differentiation of sensory neurons from human induced pluripotent stem cells
    (Springer Nature, 2022-09-23) Cantor, Erica L.; Shen, Fei; Jiang, Guanglong; Tan, Zhiyong; Cunningham, Geneva M.; Wu, Xi; Philips, Santosh; Schneider, Bryan P.; Medicine, School of Medicine
    Induced pluripotent stem cells (iPSCs) are a valuable resource for neurological disease-modeling and drug discovery due to their ability to differentiate into neurons reflecting the genetics of the patient from which they are derived. iPSC-derived cultures, however, are highly variable due to heterogeneity in culture conditions. We investigated the effect of passage number on iPSC differentiation to optimize the generation of sensory neurons (iPSC-dSNs). Three iPSC lines reprogrammed from the peripheral blood of three donors were differentiated into iPSC-dSNs at passage numbers within each of the following ranges: low (5-10), intermediate (20-26), and high (30-38). Morphology and pluripotency of the parent iPSCs were assessed prior to differentiation. iPSC-dSNs were evaluated based on electrophysiological properties and expression of key neuronal markers. All iPSC lines displayed similar morphology and were similarly pluripotent across passage numbers. However, the expression levels of neuronal markers and sodium channel function analyses indicated that iPSC-dSNs differentiated from low passage numbers better recapitulated the sensory neuron phenotype than those differentiated from intermediate or high passage numbers. Our results demonstrate that lower passage numbers may be better suited for differentiation into peripheral sensory neurons.
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    Permeation Mechanism of Potassium Ions through the Large Conductance Ca2+-Activated Potassium Channel
    (ACS, 2019-08) Guo, Jingkang; Tan, Zhiyong; Ji, Yonghua; Pharmacology and Toxicology, School of Medicine
    The permeation of the potassium ion (K+) through the selectivity filter (SF) of the large conductance Ca2+-activated potassium (Slo1) channel remains an interesting question to study. Although the mode of K+ entering and leaving the SF has been revealed, the mechanism of K+ passing through the SF is still not clear. In the present study, the pattern of K+ permeation through the SF is investigated by chemical computation and data mining based on the molecular structure of Slo1 from Aplysia californica. Both bond configurations and the free energy of K+s inside the SF was studied using Discovery Studio software. The results suggested that, to accommodate increasing energy levels and to tolerate more K+s, 4-fold symmetric subunits of SF can only move at one direction that is perpendicular to the center axis. In addition, two configurations of chemical bonds between K+s and the SF are usually employed including the chelate configuration under low free energy and the complex configuration under high free energy conditions. Moreover, three patterns of bond configurations for multiple K+s within the SF are used to accommodate the energetic changes of the SF, and each pattern is composed of one or two subconformations. These findings likely resulted from the evolutionary optimization of the protein function of Slo1. The specific conductance and the voltage-gating of the Slo1 channel can be reinterpreted with the permeation mechanism of K+s found in the current study. The permeation mechanism of K+s through the SF can be used to understand the interaction between various toxins and the Slo1 channel, and can be employed to develop new drugs targeting relevant ion channels.
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    SAT074 Induction Of Insulin Hypersecretion Uncovers Distinctions Between Adaptive And Maladaptive Endoplasmic Reticulum Stress Response In Beta Cells
    (The Endocrine Society, 2023-10-05) Roy, Gitanjali; Rodrigues dos Santos, Karina; Kwakye, Michael B.; Tan, Zhiyong; Johnson, Travis S.; Kalwat, Michael A.; Biostatistics and Health Data Science, School of Medicine
    Pancreatic islet β-cells release insulin to maintain glucose homeostasis. β-cells must translate, package, and secrete large amounts of insulin. During this process the unfolded protein response of the endoplasmic reticulum (UPRER) is induced to maintain these functions. However, stimuli that force β-cell to secrete insulin at enhanced rates and for prolonged durations risk inducing the terminal UPRER and eventual apoptosis. In a chemical screen for insulin secretion modulators, we discovered SW016789 which caused hypersecretion of insulin and led to a transient induction of the UPRER, but not apoptosis. In contrast, SERCA2 ER Ca2+ pump inhibitor thapsigargin induces the terminal UPRER. We hypothesized that SW016789 can be used as a tool compound to discover genes involved in β-cell adaptation to hypersecretion-induced stress. We performed time course transcriptomics in MIN6 β-cells exposed to SW016789 (5 µM) or thapsigargin (100 nM) from 0-24 h. Unbiased analyses using a Dirichlet process Gaussian process (DPGP) method revealed clusters of genes temporally co-regulated and the genes within these clusters were distinct between SW016789 and thapsigargin treatments. In particular, after 6 h of SW016789-induced hypersecretion we found a highly induced cluster of genes (SW cluster 3) enriched in adaptive UPRER factors (e.g. Manf). Conversely, most of the thapsigargin-induced genes clustered at 24 h and were enriched for terminal UPRER factors (e.g. Txnip). Pathway analysis of SW cluster 3 indicated that genes involved in in regulation of mRNA methylation and ER-associated degradation were also induced by SW016789 sooner and with greater amplitude than by thapsigargin, suggesting distinct differences in the handling of protein translation and degradation. From the SW cluster 3 genes we selected proteins known to be ER-associated or secreted and generated stable transgenic or CRISPR knockout MIN6 β-cell lines for each. Our data suggest altered expression of these factors may impair glucose-stimulated insulin secretion responses and alter cell viability in presence or absence of ER stressors including cytokines, thapsigargin, and tunicamycin. In conclusion, we have successfully shown that pharmacological induction of insulin hypersecretion can induce a distinct transcriptional outcome from that of canonically-induced UPRER and that we can take advantage of this property to discover new β-cell regulatory pathways and targets. We envision this dataset as a resource for the secretory biology and islet biology communities.