Lanthionine ketimine ester improves outcome in an MPTP-induced mouse model of Parkinson's disease via suppressions of CRMP2 phosphorylation and microglial activation

Neurodegeneration models in Parkinson's disease: cellular and molecular paths to neuron death

Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects dopaminergic neurons in the substantia nigra pars compacta. It is a complex disease that is strongly influenced by environmental and genetic factors. While the exact causes of PD are not well understood, research on the effects of toxic substances that induce neuronal death has shed some light on the etiology of the disease. In addition, studies have implicated protein aggregation and impaired mitochondrial, endoplasmic reticulum (ER), proteasome, and/or lysosomal function in the pathogenesis of PD. This review focuses on the alterations in intraneuronal organelles and the role of toxic agents that lead to organelle damage and neurodegeneration that characterize PD. We describe in vivo and in vitro models that have been used to elucidate the factors that lead to the death of dopaminergic neurons and summarize the molecular mechanisms that may underlie the changes that promote neurodegeneration. A deeper understanding of the mechanisms of neuronal death may help us to develop new therapies and interventions to delay or prevent the progression of PD.

Unraveling the Nexus: The Role of Collapsin Response Mediator Protein 2 Phosphorylation in Neurodegeneration and Neuroregeneration

Neurodegenerative disease characterized by the progressive damage of the nervous system, and neuropathies caused by the neuronal injury are both led to substantial impairments in neural function and quality of life among geriatric populations. Recovery from nerve damage and neurodegenerative diseases present a significant challenge, as the central nervous system (CNS) has limited capacity for self-repair. Investigating mechanism of neurodegeneration and regeneration is essential for advancing our understanding and development of effective therapies for nerve damage and degenerative conditions, which can significantly enhance patient outcomes. Collapsin response mediator protein 2 (CRMP2) was first identified as a key mediator of axonal growth and guidance is essential for neurogenesis and neuroregeneration. Phosphorylation as a primary modification approach of CRMP2 facilitates its involvement in numerous physiological processes, including axonal guidance, neuroplasticity, and cytoskeleton dynamics. Prior research on CRMP2 phosphorylation has elucidated its involvement in the mechanisms of neurodegenerative diseases and nerve damage. Pharmacological and genetic interventions that alter CRMP2 phosphorylation have shown the potential to influence neurodegenerative diseases and promote nerve regeneration. Even with decades of research delving into the intricacies of CRMP2 phosphorylation, there remains a scarcity of comprehensive literature reviews addressing this topic. This absence of synthesis and integration of findings hampers the field's progress by preventing a holistic understanding of CRMP2's implications in neurobiology, thereby impeding potential advancements in clinical treatments and interventions. This review intends to compile investigations focused on the role of CRMP2 phosphorylation in both neurodegenerative disease models and injury models to summarizing impacts and offer novel insight for clinical therapies.

CTB-targeted protocells enhance ability of lanthionine ketenamine analogs to induce autophagy in motor neuron-like cells

Impaired autophagy, a cellular digestion process that eliminates proteins and damaged organelles, has been implicated in neurodegenerative diseases, including motor neuron disorders. Motor neuron targeted upregulation of autophagy may serve as a promising therapeutic approach. Lanthionine ketenamine (LK), an amino acid metabolite found in mammalian brain tissue, activates autophagy in neuronal cell lines. We hypothesized that analogs of LK can be targeted to motor neurons using nanoparticles to improve autophagy flux. Using a mouse motor neuron-like hybrid cell line (NSC-34), we tested the effect of three different LK analogs on autophagy modulation, either alone or loaded in nanoparticles. For fluorescence visualization of autophagy flux, we used a mCherry-GFP-LC3 plasmid reporter. We also evaluated protein expression changes in LC3-II/LC3-I ratio obtained by western blot, as well as presence of autophagic vacuoles per cell obtained by electron microscopy. Delivering LK analogs with targeted nanoparticles significantly enhanced autophagy flux in differentiated motor neuron-like cells compared to LK analogs alone, suggesting the need of a delivery vehicle to enhance their efficacy. In conclusion, LK analogs loaded in nanoparticles targeting motor neurons constitute a promising treatment option to induce autophagy flux, which may serve to mitigate motor neuron degeneration/loss and preserve motor function in motor neuron disease.

Mepirapim, a novel synthetic cannabinoid, induces Parkinson's disease-related behaviors by causing maladaptation of the dopamine system in the brain

Mepirapim is a novel synthetic cannabinoid that first appeared on the illicit drug market in 2013. In recent years, recreational abuse of Mepirapim has caused serious emergencies, posing a threat to public health. However, there are no legal regulations to prohibit the use of Mepirapim, as there is no scientific evidence for the dangerous pharmacological effects of the drug. In the present study, we investigated the dangerous neurotoxic effects of Mepirapim through behavioral and molecular experiments in mice (ICR/CD1, male, 25-30 g). In particular, based on a previous study that Mepirapim activates the dopamine system, we evaluated whether high-dose Mepirapim [single (15, 30, or 60 mg·kg^-1, i.p.) or multiple (8, 15, or 30 mg·kg^-1, i.p. × 4 at 2 h intervals)] treatment causes Parkinson's disease-related symptoms through damage to the dopamine system. In the result, we found that Mepirapim treatment caused comprehensive Parkinson's disease-related symptoms, including motor impairment, cognitive deficits and mood disorders. Furthermore, we confirmed the maladaptation in dopamine-related neurochemicals, including decreased dopamine levels, decreased tyrosine hydroxylase expression, and increased α-synuclein expression, in the brains of mice treated with Mepirapim. Taken together, these results indicate that Mepirapim has dangerous neurotoxic effects that induces Parkinson's disease-related behaviors by causing maladaptation of the dopamine system in the brain. Based on these findings, we propose the strict regulation of recreational abuse and therapeutic misuse of Mepirapim.

Effects of Lanthionine Ketimine-5-Ethyl Ester on the α-Synucleinopathy Mouse Model

Potentially druggable mechanisms underlying synaptic deficits seen in Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are under intense interrogations. In addition to defective synaptic vesicle trafficking, cytoskeletal disruption, autophagic perturbation, and neuroinflammation, hyperphosphorylation of microtubule-associated protein collapsin response mediator protein 2 (CRMP2, also known as DPYSL2) is newly determined to correlate with synaptic deficits in human DLB. The small molecule experimental therapeutic, lanthionine ketimine-5-ethyl ester (LKE), appears to interact with CRMP2 in a host of neurodegenerative mouse models, normalizing its phosphorylation level while promoting healthful autophagy in cell culture models and suppressing the proinflammatory phenotype of activated microglia. Accordingly, this study examined the effect of LKE on α-synuclein A53T transgenic (Tg) mice which were employed as a DLB model. We found that chronic administration of LKE to A53T mice suppressed (1) the accumulation of LBs, (2) neuroinflammatory activation of microglia, (3) impairment of contextual fear memory, and (4) CRMP2 phosphorylation at Thr509 in A53T Tg mice. These results suggest that CRMP2 phosphorylation by GSK3β in the hippocampus is related to pathology and memory impairment in DLB, and LKE may have clinical implications in the treatment of α-synucleinopathy.

Chemistry of Outlandish Natural Products Belonging to Sulfur Metabolism: Unrevealed Green Syntheses and Separation Strategies from the Cavallini’s Old School

The last century has been very important from the point of view of research and investigation in the fields of the chemistry and biochemistry of sulfur-containing natural products. One of the most important contributions to the discovery and study of human sulfur-containing metabolites was performed by the research group of Professor Doriano Cavallini at Sapienza University of Rome, during the last 80 years. His research brought to light the discovery of unusual sulfur metabolites that were chemically synthesized and determined in different biological specimens. Most of his synthetical strategies were performed in aqueous conditions, which nowadays can be considered totally in line with the recent concepts of the green chemistry. The aim of this paper is to describe and summarize synthetic procedures, and purification and analytical methods from the Cavallini’s school, with the purpose to provide efficient and green methodologies for the preparation and obtainment of peculiar unique sulfur-containing metabolites.

MPTP-induced mouse model of Parkinson's disease: A promising direction of therapeutic strategies

Among the popular animal models of Parkinson's disease (PD) commonly used in research are those that employ neurotoxins, especially 1-methyl- 4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). This neurotoxin exerts it neurotoxicity by causing a barrage of insults, such as oxidative stress, mitochondrial apoptosis, inflammation, excitotoxicity, and formation of inclusion bodies acting singly and in concert, ultimately leading to dopaminergic neuronal damage in the substantia nigra pars compacta and striatum. The selective neurotoxicity induced by MPTP in the nigrostriatal dopaminergic neurons of the mouse brain has led to new perspectives on PD. For decades, the MPTP-induced mouse model of PD has been the gold standard in PD research even though it does not fully recapitulate PD symptomatology, but it does have the advantages of simplicity, practicability, affordability, and fewer ethical considerations and greater clinical correlation than those of other toxin models of PD. The model has rejuvenated PD research and opened new frontiers in the quest for more novel therapeutic and adjuvant agents for PD. Hence, this review summarizes the role of MPTP in producing Parkinson-like symptoms in mice and the experimental role of the MPTP-induced mouse model. We discussed recent developments of more promising PD therapeutics to enrich our existing knowledge about this neurotoxin using this model.