Neuroprotective effects of ZL006 in Aβ1-42-treated neuronal cells

ZL006 mitigates anxiety-like behaviors induced by closed head injury through modulation of the neural circuit from the medial prefrontal cortex to amygdala

Closed head injury is a prevalent form of traumatic brain injury with poorly understood effects on cortical neural circuits. Given the emotional and behavioral impairments linked to closed head injury, it is vital to uncover brain functional deficits and their driving mechanisms. In this study, we employed a robust viral tracing technique to identify the alteration of the neural pathway connecting the medial prefrontal cortex to the basolateral amygdala, and we observed the disruptions in neuronal projections between the medial prefrontal cortex and the basolateral amygdala following closed head injury. Remarkably, our results highlight that ZL006, an inhibitor targeting PSD-95/nNOS interaction, stands out for its ability to selectively reverse these aberrations. Specifically, ZL006 effectively mitigates the disruptions in neuronal projections from the medial prefrontal cortex to basolateral amygdala induced by closed head injury. Furthermore, using chemogenetic approaches, we elucidate that activating the medial prefrontal cortex projections to the basolateral amygdala circuit produces anxiolytic effects, aligning with the therapeutic potential of ZL006. Additionally, ZL006 administration effectively mitigates astrocyte activation, leading to the restoration of medial prefrontal cortex glutamatergic neuron activity. Moreover, in the context of attenuating anxiety-like behaviors through ZL006 treatment, we observe a reduction in closed head injury-induced astrocyte engulfment, which may correlate with the observed decrease in dendritic spine density of medial prefrontal cortex glutamatergic neurons.

Neuronal Nitric Oxide Synthase and Post-Translational Modifications in the Development of Central Nervous System Diseases: Implications and Regulation

In the Central Nervous System (CNS), Nitric Oxide (NO) is mainly biosynthesized by neuronal Nitric Oxide Synthase (nNOS). The dysregulated activation of nNOS in neurons is critical in the development of different conditions affecting the CNS. The excessive production of NO by nNOS is responsible for a number of proteins' post-translational modifications (PTMs), which can lead to aberrant biochemical pathways, impairing CNS functions. In this review, we briefly revise the main implications of dysregulated nNOS in the progression of the most prevalent CNS neurodegenerative disorders, i.e., Alzheimer's disease (AD) and Parkinson's disease, as well as in the development of neuronal disorders. Moreover, a specific focus on compounds able to modulate nNOS activity as promising therapeutics to tackle different neuronal diseases is presented.

nNOS and Neurological, Neuropsychiatric Disorders: A 20-Year Story

In the central nervous system, nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS). In the past 20 years, the studies in our group and other laboratories have suggested a significant involvement of nNOS in a variety of neurological and neuropsychiatric disorders. In particular, the interactions between the PDZ domain of nNOS and its adaptor proteins, including post-synaptic density 95, the carboxy-terminal PDZ ligand of nNOS, and the serotonin transporter, significantly influence the subcellular localization and functions of nNOS in the brain. The nNOS-mediated protein-protein interactions provide new attractive targets and guide the discovery of therapeutic drugs for neurological and neuropsychiatric disorders. Here, we summarize the work on the roles of nNOS and its association with multiple adaptor proteins on neurological and neuropsychiatric disorders.

RALBP1 in Oxidative Stress and Mitochondrial Dysfunction in Alzheimer's Disease

The purpose of our study is to understand the role of the RALBP1 gene in oxidative stress (OS), mitochondrial dysfunction and cognition in Alzheimer's disease (AD) pathogenesis. The RALPB1 gene encodes the 76 kDa protein RLIP76 (Rlip). Rlip functions as a stress-responsive/protective transporter of glutathione conjugates (GS-E) and xenobiotic toxins. We hypothesized that Rlip may play an important role in maintaining cognitive function. The aim of this study is to determine whether Rlip deficiency in mice is associated with AD-like cognitive and mitochondrial dysfunction. Brain tissue obtained from cohorts of wildtype (WT) and Rlip^+/- mice were analyzed for OS markers, expression of genes that regulate mitochondrial fission/fusion, and synaptic integrity. We also examined mitochondrial ultrastructure in brains obtained from these mice and further analyzed the impact of Rlip deficiency on gene networks of AD, aging, stress response, mitochondrial function, and CREB signaling. Our studies revealed a significant increase in the levels of OS markers and alterations in the expression of genes and proteins involved in mitochondrial biogenesis, dynamics and synapses in brain tissues from these mice. Furthermore, we compared the cognitive function of WT and Rlip^+/- mice. Behavioral, basic motor and sensory function tests in Rlip^+/- mice revealed cognitive decline, similar to AD. Gene network analysis indicated dysregulation of stress-activated gene expression, mitochondrial function and CREB signaling genes in the Rlip^+/- mouse brain. Our results suggest that Rlip deficiency-associated increases in OS and mitochondrial dysfunction could contribute to the development or progression of OS-related AD processes.

Sorafenib not only impairs endothelium-dependent relaxation but also promotes vasoconstriction through the upregulation of vasoconstrictive endothelin type B receptors

As a VEGF-targeting agent, sorafenib has been used to treat a number of solid tumors but can easily lead to adverse vascular effects. To elucidate the underlying mechanism, rat mesenteric arteries were subjected to organ cultured in the presence of different concentrations of sorafenib (0, 3, 6 and 9 mg/L) with or without inhibitors (U0126, 10-5 M; SB203580, 10-5 M; SP200126, 10-5 M) of MAPK kinases, and then acetylcholine- or sodium nitroprusside-induced vasodilation and sarafotoxin 6c-induced vasoconstriction were monitored by a sensitive myograph. The NO synthetases, the nitrite levels, the endothelial marker CD31,the ETB and ETA receptors and the phosphorylation of MAPK kinases were studied. Next, rats were orally administrated by sorafenib for 4 weeks (7.5 and 15 mg/kg/day), and their blood pressure, plasma ET-1, the ETB and ETA receptors and the phosphorylation of MAPK kinases in the mesenteric arteries were investigated. The results showed that sorafenib impairs endothelium-dependent vasodilation due to decreased NO levels and the low expression of eNOS and iNOS. Weak staining for CD31 indicated that sorafenib induced endothelial damage. Moreover, sorafenib caused the upregulation of vasoconstrictive ETB receptors, the enhancement of ETB receptor-mediated vasoconstriction and the activation of JNK/MAPK. Blocking the JNK, ERK1/2 and p38/MAPK signaling pathways by using the inhibitors significantly abolished ETB receptor-mediated vasoconstriction. Furthermore, it was observed that the oral administration of sorafenib caused an increase in blood pressure and plasma ET-1, upregulation of the ETB receptor and the activation of JNK in the mesenteric arteries. In conclusion, sorafenib not only impairs endothelium-dependent vasodilatation but also enhances ETB receptor-mediated vasoconstriction, which may be the causal factors for hypertension and other adverse vascular effects in patients treated with sorafenib.

nNOS-mediated protein-protein interactions: promising targets for treating neurological and neuropsychiatric disorders

Neurological and neuropsychiatric disorders are one of the leading causes of disability worldwide and affect the health of billions of people. Nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS) in the brain. Inhibiting nNOS benefits a variety of neurological and neuropsychiatric disorders, including stroke, depression and anxiety disorders, post-traumatic stress disorder, Parkinson's disease, Alzheimer's disease, chronic pain, and drug addiction. Due to critical roles of nNOS in learning and memory and synaptic plasticity, direct inhibition of nNOS may cause severe side effects. Importantly, interactions of several proteins, including post-synaptic density 95 (PSD-95), carboxy-terminal PDZ ligand of nNOS (CAPON) and serotonin transporter (SERT), with the PSD/Disc-large/ZO-1 homologous (PDZ) domain of nNOS have been demonstrated to influence the subcellular distribution and activity of the enzyme in the brain. Therefore, it will be a preferable means to interfere with nNOS-mediated protein-protein interactions (PPIs), which do not lead to undesirable effects. Herein, we summarize the current literatures on nNOS-mediated PPIs involved in neurological and neuropsychiatric disorders, and the discovery of drugs targeting the PPIs, which is expected to provide potential targets for developing novel drugs and new strategy for the treatment of neurological and neuropsychiatric disorders.