Potential role of serotonin as a biological reductant associated with copper transportation

Unraveling Copper Imbalance in Autism Spectrum Disorder: Mechanistic Insights from the Valproic Acid Mouse Model

Abnormal copper (Cu) levels are often closely associated with neurological disorders including neurodevelopmental conditions, such as autism spectrum disorder (ASD). However, the mechanisms underlying the disruption of Cu homeostasis in critical organs, such as the brain, remain unclear. In this study, we elucidated the molecular mechanisms of Cu imbalance in the brain of a valproic acid (VPA) mouse model along with the changes in specific metabolites. Significant alterations occurred in proteins associated with primary Cu-related metabolism in specific regions of the brain (prefrontal cortex, amygdala, cerebellum, and hippocampus), resulting in a direct elevation of Cu ions within the brain tissues (control: 5.05 ± 0.61 μg/g vs model: 6.28 ± 0.81 μg/g, p = 0.015). Furthermore, the brain metabolic profiles revealed significant upregulation of lipids, particularly phospholipid metabolites. Typical neurotransmitters, for example, dopamine (DA) (p < 0.0001) and serotonin (5-HT) (p = 0.02) were upregulated in amygdala. Other small metabolites like glutathione (GSH) (p = 0.0004) also exhibited notable variation in brain. The potential impact of Cu toxicity on the signaling pathways of key metabolites was then evaluated, providing new insights into the role of Cu in metabolism of neurotransmitters in the brain. Our finding sheds molecular aberrations associated with essential element metabolism in the brain, providing new elemental perspectives for understanding the pathogenic mechanisms underlying ASD.

Psychiatric Symptoms in Wilson's Disease-Consequence of ATP7B Gene Mutations or Just Coincidence?-Possible Causal Cascades and Molecular Pathways

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism. The genetic defect in WD affects the ATP7B gene, which encodes the ATP7B transmembrane protein, which is essential for maintaining normal copper homeostasis in the body. It is primarily expressed in the liver and acts by incorporating copper into ceruloplasmin (Cp), the major copper transport protein in the blood. In conditions of excess copper, ATP7B transports it to bile for excretion. Mutations in ATP7B lead to impaired ATP7B function, resulting in copper accumulation in hepatocytes leading to their damage. The toxic "free"-unbound to Cp-copper released from hepatocytes then accumulates in various organs, contributing to their damage and clinical manifestations of WD, including hepatic, neurological, hematological, renal, musculoskeletal, ophthalmological, psychiatric, and other effects. While most clinical manifestations of WD correspond to identifiable organic or cellular damage, the pathophysiology underlying its psychiatric manifestations remains less clearly understood. A search for relevant articles was conducted in PubMed/Medline, Science Direct, Scopus, Willy Online Library, and Google Scholar, combining free text and MeSH terms using a wide range of synonyms and related terms, including "Wilson's disease", "hepatolenticular degeneration", "psychiatric manifestations", "molecular mechanisms", "pathomechanism", and others, as well as their combinations. Psychiatric symptoms of WD include cognitive disorders, personality and behavioral disorders, mood disorders, psychosis, and other mental disorders. They are not strictly related to the location of brain damage, therefore, the question arises whether these symptoms are caused by WD or are simply a coincidence or a reaction to the diagnosis of a genetic disease. Hypotheses regarding the etiology of psychiatric symptoms of WD suggest a variety of molecular mechanisms, including copper-induced CNS toxicity, oxidative stress, mitochondrial dysfunction, mitophagy, cuproptosis, ferroptosis, dysregulation of neurotransmission, deficiencies of neurotrophic factors, or immune dysregulation. New studies on the expression of noncoding RNA in WD are beginning to shed light on potential molecular pathways involved in psychiatric symptomatology. However, current evidence is still insufficient to definitively establish the cause of psychiatric symptoms in WD. It is possible that the etiology of psychiatric symptoms varies among individuals, with multiple biological and psychological mechanisms contributing to them simultaneously. Future studies with larger samples and comprehensive analyses are necessary to elucidate the mechanisms underlying the psychiatric manifestations of WD and to optimize diagnostics and therapeutic approaches.

Imbalance of Essential Metals in Traumatic Brain Injury and Its Possible Link with Disorders of Consciousness

Dysfunction of the complex cerebral networks underlying wakefulness and awareness is responsible for Disorders of Consciousness (DoC). Traumatic Brain Injury (TBI) is a common cause of DoC, and it is responsible for a multi-dimensional pathological cascade that affects the proper functioning of the brainstem and brain consciousness pathways. Iron (Fe), Zinc (Zn), and Copper (Cu) have a role in the neurophysiology of both the ascending reticular activating system, a multi-neurotransmitter network located in the brainstem that is crucial for consciousness, and several brain regions. We aimed to summarize the role of these essential metals in TBI and its possible link with consciousness alterations. We found that TBI alters many neuronal molecular mechanisms involving essential metals, causing neurodegeneration, neural apoptosis, synaptic dysfunction, oxidative stress, and inflammation. This final pattern resembles that described for Alzheimer's disease (AD) and other neurological and psychiatric diseases. Furthermore, we found that amantadine, zolpidem, and transcranial direct current stimulation (tDCS)-the most used treatments for DoC recovery-seem to have an effect on essential metals-related pathways and that Zn might be a promising new therapeutic approach. This review summarizes the neurophysiology of essential metals in the brain structures of consciousness and focuses on the mechanisms underlying their imbalance following TBI, suggesting their possible role in DoC. The scenario supports further studies aimed at getting a deeper insight into metals' role in DoC, in order to evaluate metal-based drugs, such as metal complexes and metal chelating agents, as potential therapeutic options.

Expanding the Landscape of Amino Acid-Rich Antimicrobial Peptides: Definition, Deployment in Nature, Implications for Peptide Design and Therapeutic Potential

Unlike the α-helical and β-sheet antimicrobial peptides (AMPs), our knowledge on amino acid-rich AMPs is limited. This article conducts a systematic study of rich AMPs (>25%) from different life kingdoms based on the Antimicrobial Peptide Database (APD) using the program R. Of 3425 peptides, 724 rich AMPs were identified. Rich AMPs are more common in animals and bacteria than in plants. In different animal classes, a unique set of rich AMPs is deployed. While histidine, proline, and arginine-rich AMPs are abundant in mammals, alanine, glycine, and leucine-rich AMPs are common in amphibians. Ten amino acids (Ala, Cys, Gly, His, Ile, Lys, Leu, Pro, Arg, and Val) are frequently observed in rich AMPs, seven (Asp, Glu, Phe, Ser, Thr, Trp, and Tyr) are occasionally observed, and three (Met, Asn, and Gln) were not yet found. Leucine is much more frequent in forming rich AMPs than either valine or isoleucine. To date, no natural AMPs are simultaneously rich in leucine and lysine, while proline, tryptophan, and cysteine-rich peptides can simultaneously be rich in arginine. These findings can be utilized to guide peptide design. Since multiple candidates are potent against antibiotic-resistant bacteria, rich AMPs stand out as promising future antibiotics.