Browsing by Subject "Molecular pathways"

Now showing 1 - 4 of 4
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    77822 PSD95-nNOS interaction alters the basolateral amygdala transcriptome following fear conditioning: implications for molecular mechanisms underlying PTSD
    (Cambridge University Press, 2021) Patel, Jheel; Haulcomb, Melissa; Li, Liangping; Jiang, Guanglong; Dustrude, Erik; Liu, Yunlong; Lai, Yvonne; Molosh, Andrei; Shekhar, Anantha; Medicine, School of Medicine
    ABSTRACT IMPACT: This research takes a transcriptomic approach to parse genes and molecular pathways that underlie the fear memory circuitry and, in doing so, identifies therapeutic targets that can further be developed into treatments for fear disorders, such as post-traumatic stress disorder. OBJECTIVES/GOALS: Normal fear learning produces avoidance behavior that promotes survival, but excessive and persistent fear after trauma can lead to development of phobias and post-traumatic stress disorder (PTSD). Our goal is to understand the mechanism and identify novel genetic targets underlying fear responses. METHODS/STUDY POPULATION: Involvement of the basolateral amygdala (BLA) in fear acquisition is well established and requires activation of N-methyl-D-aspartic acid receptors (NMDARs). At a cellular level, NMDAR activation leads to production of nitric oxide (NO) by a process mediated by interaction between postsynaptic density protein 95 (PSD95) and neuronal nitric oxide synthase (nNOS). To elucidate mechanisms underlying the role of the PSD95-nNOS-NO pathway in conditioned fear, here we use rodent behavioral paradigms, pharmacological treatment with a small molecule PSD95-nNOS inhibitor, RNA-sequencing, and an AAV-mediated knockdown of the nNOS gene in the BLA. RESULTS/ANTICIPATED RESULTS: We show that treatment with ZL006 attenuates rodent cued-fear consolidation. Additionally, with RNA-sequencing, expression of 516 genes was altered in the BLA following fear expression; of these genes, 83 were restored with systemic ZL006 treatment. Network data and gene ontology enrichment analyses further revealed that cGMP effects, insulin-like growth factor binding, and cognition-related pathways were significantly altered. Finally, we show that a BLA-specific knockdown of nNOS attenuates cued fear consolidation, without adverse effects on other memory and motor behaviors. DISCUSSION/SIGNIFICANCE OF FINDINGS: Via a model of NMDAR-mediated fear consolidation, our results reveal novel pathways and genetic targets that underlie plasticity of fear memory circuitry. Importantly, these results will inform future therapeutic strategies for targeting fear related disorders like PTSD.
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    Glucocorticoid induced osteoporosis and mechanisms of intervention
    (2017-03) Sato, Amy Yoshiko; Bellido, Teresita; Plotkin, Lilian I.; Pavalko, Fredrick M.; Robling, Alexander G.
    Glucocorticoid excess is a leading cause of osteoporosis. The loss of bone mass and strength corresponds to the increase in fractures exhibited after three months of glucocorticoid therapy. Glucocorticoids induce the bone cellular responses of deceased bone formation, increased osteoblast/osteocyte apoptosis, and transient increased bone resorption, which result in rapid bone loss and degradation of bone microarchitecture. The current standard of care for osteoporosis is bisphosphonate treatment; however, these agents further suppress bone formation and increase osteonecrosis and low energy atypical fracture risks. Thus, there is an unmet need for interventions that protect from glucocorticoid therapy. The purpose of these studies was to investigate novel mechanisms that potentially interfere with glucocorticoid-induced bone loss. We chose to explore pathways that regulate endoplasmic reticulum stress, the canonical Wnt pathway, and Pyk2 activity. Pharmacologic reduction of endoplasmic reticulum stress through salubrinal administration protected against glucocorticoid-induced bone loss by preservation of bone formation and osteoblast/osteocyte viability. In contrast, inhibition of Wnt antagonist Sost/sclerostin and inhibition of Pyk2 signaling did not prevent glucocorticoid-induced reductions in bone formation; however, both Sost/sclerostin and Pyk2 deficiency protected against bone loss through inhibition of increases in resorption. Overall, these studies demonstrate the significant contributions of reductions in bone formation, increased osteoblast/osteocyte apoptosis, and elevations in resorption to the rapid 6-12% bone loss exhibited during the first year of glucocorticoid therapy. However, glucocorticoid excess also induces skeletal muscle weakness, which is not reversed by bisphosphonate treatment or the interventions reported here of salubrinal, Sost/sclerostin inhibition, or Pyk2 deficiency. Further, the novel finding of increased E3 ubiquitin ligase atrophy signaling induce by glucocorticoids in both bone and muscle, by tissue-specific upstream mechanisms, provides opportunities for therapeutic combination strategies. Thus, future studies are warranted to investigate the role of E3 ubiquitin ligase signaling in the deleterious glucocorticoid effects of bone and muscle.
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    Protection From Glucocorticoid-Induced Osteoporosis by Anti-Catabolic Signaling in the Absence of Sost/Sclerostin
    (Wiley, 2016-10) Sato, Amy Y.; Cregor, Meloney; Delgado-Calle, Jesus; Condon, Keith W.; Allen, Matthew R.; Peacock, Munro; Plotkin, Lilian I.; Bellido, Teresita; Anatomy, Cell Biology and Physiology, School of Medicine
    Excess of glucocorticoids, either due to disease or iatrogenic, increases bone resorption and decreases bone formation and is a leading cause of osteoporosis and bone fractures worldwide. Improved therapeutic strategies are sorely needed. We investigated whether activating Wnt/β-catenin signaling protects against the skeletal actions of glucocorticoids, using female mice lacking the Wnt/β-catenin antagonist and bone formation inhibitor Sost. Glucocorticoids decreased the mass, deteriorated the microarchitecture, and reduced the structural and material strength of bone in wild-type (WT), but not in Sost-/- mice. The high bone mass exhibited by Sost-/- mice is due to increased bone formation with unchanged resorption. However, unexpectedly, preservation of bone mass and strength in Sost-/- mice was due to prevention of glucocorticoid-induced bone resorption and not to restoration of bone formation. In WT mice, glucocorticoids increased the expression of Sost and the number of sclerostin-positive osteocytes, and altered the molecular signature of the Wnt/β-catenin pathway by decreasing the expression of genes associated with both anti-catabolism, including osteoprotegerin (OPG), and anabolism/survival, such as cyclin D1. In contrast in Sost-/- mice, glucocorticoids did not decrease OPG but still reduced cyclin D1. Thus, in the context of glucocorticoid excess, activation of Wnt/β-catenin signaling by Sost/sclerostin deficiency sustains bone integrity by opposing bone catabolism despite markedly reduced bone formation and increased apoptosis. This crosstalk between glucocorticoids and Wnt/β-catenin signaling could be exploited therapeutically to halt resorption and bone loss induced by glucocorticoids and to inhibit the exaggerated bone formation in diseases of unwanted hyperactivation of Wnt/β-catenin signaling.
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    A serine protease KLK8 emerges as a regulator of regulators in memory: Microtubule protein dependent neuronal morphology and PKA-CREB signaling
    (Nature Publishing Group, 2018-07-02) Konar, Arpita; Kumar, Ashish; Maloney, Bryan; Lahiri, Debomoy K.; Thakur, Mahendra K.; Psychiatry, School of Medicine
    The multitude of molecular pathways underlying memory impairment in neurological disorders and aging-related disorders has been a major hurdle against therapeutic targeting. Over the years, neuronal growth promoting factors, intracellular kinases, and specific transcription factors, particularly cyclic AMP response element-binding protein (CREB), have emerged as crucial players of memory storage, and their disruption accompanies many cognitive disabilities. However, a molecular link that can influence these major players and can be a potential recovery target has been elusive. Recent reports suggest that extracellular cues at the synapses might evoke an intracellular signaling cascade and regulate memory function. Herein, we report novel function of an extracellular serine protease, kallikrein 8 (KLK8/Neuropsin) in regulating the expression of microtubule associated dendrite growth marker microtubule-associated protein (MAP2)c, dendrite architecture and protein kinase A (PKA)-CREB signaling. Both knockdown of KLK8 via siRNA transfection in mouse primary hippocampal neurons and via intra-hippocampal administration of KLK8 antisense oligonucleotides in vivo reduced expression of MAP2c, dendrite length, dendrite branching and spine density. The KLK8 mediated MAP2c deficiency in turn inactivated PKA and downstream transcription factor phosphorylated CREB (pCREB), leading to downregulation of memory-linked genes and consequent impaired memory consolidation. These findings revealed a protease associated novel pathway of memory impairment in which KLK8 may act as a "regulator of regulators", suggesting its exploration as an important therapeutic target of memory disorders.