pLG72 induces superoxide radicals via interaction and aggregation with SOD1

Interpretable machine learning to evaluate relationships between DAO/DAOA (pLG72) protein data and features in clinical assessments, functional outcome, and cognitive function in schizophrenia patients

Machine learning has been proposed to utilize D-amino acid oxidase (DAO) and DAO activator (DAOA [or pLG72]) protein levels to ascertain disease status in schizophrenia. However, it remains unclear whether machine learning can effectively evaluate clinical features in relation to DAO and DAOA in schizophrenia patients. We employed an interpretable machine learning (IML) framework including linear regression, least absolute shrinkage and selection operator (Lasso) models, and generalized additive models (GAMs) to analyze DAO/DAOA levels using 380 Taiwanese schizophrenia patients. Additionally, we incorporated 27 parameters encompassing demographic variables, clinical assessments, functional outcomes, and cognitive function as features. The IML framework facilitated linear and non-linear relationships between features and DAO/DAOA. DAO levels demonstrated significant associations with the 17-item Hamilton Depression Rating Scale (HAMD17) based on linear regression. The Lasso model identified four features-HAMD17, age, working memory, and overall cognitive function (OCF)-and highlighted HAMD17 as the most significant feature, using DAO from chronically stable patients. Utilizing DAOA from acutely exacerbated patients, the Lasso model also identified four features-OCF, Scale for the Assessment of Negative Symptoms 20-item, quality of life scale (QLS), and category fluency-and emphasized OCF as the most significant feature. Furthermore, GAMs revealed a non-linear relationship between category fluency and DAO in chronically stable patients, as well as between QLS and DAOA in acutely exacerbated patients. The study suggests that an IML framework holds promise for assessing linear and non-linear relationships between DAO/DAOA and various features in clinical assessments, functional outcomes, and cognitive function in patients with schizophrenia.

The presence and clinical significance of autoantibodies in amyotrophic lateral sclerosis: a narrative review

Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease, which is characterized by the selective loss of the upper and lower motor neurons. The pathogenesis of ALS remains to be elucidated and has been connected to genetic, environmental and immune conditions. Evidence from clinical and experimental studies has suggested that the immune system played an important role in ALS pathophysiology. Autoantibodies are essential components of the immune system. Several autoantibodies directed at antigens associated with ALS pathogenesis have been identified in the serum and/or cerebrospinal fluid of ALS patients. The aim of this review is to summarize the presence and clinical significance of autoantibodies in ALS.

Biochemical Properties and Physiological Functions of pLG72: Twenty Years of Investigations

In 2002, the novel human gene G72 was associated with schizophrenia susceptibility. This gene encodes a small protein of 153 amino acids, named pLG72, which represents a rare case of primate-specific protein. In particular, the rs2391191 single nucleotide polymorphism (resulting in in the R30K substitution) was robustly associated to schizophrenia and bipolar disorder. In this review, we aim to summarize the results of 20 years of biochemical investigations on pLG72. The main known role of pLG72 is related to its ability to bind and inactivate the flavoenzyme d-amino acid oxidase, i.e., the enzyme that controls the catabolism of d-serine, the main NMDA receptor coagonist in the brain. pLG72 was proposed to target the cytosolic form of d-amino acid oxidase for degradation, preserving d-serine and protecting the cell from oxidative stress generated by hydrogen peroxide produced by the flavoenzyme reaction. Anyway, pLG72 seems to play additional roles, such as affecting mitochondrial functions. The level of pLG72 in the human body is still a controversial issue because of its low expression and challenging detection. Anyway, the intriguing hypothesis that pLG72 level in blood could represent a suitable marker of Alzheimer’s disease progression (a suggestion not sufficiently established yet) merits further investigations.

Is the primate-specific protein pLG72 affecting SOD1 functionality and superoxide formation?

pLG72 is a primate-specific protein of enigmatic function that was proposed to modulate mitochondria fragmentation and the activity of the peroxisomal enzyme D-amino acid oxidase (DAAO). DAAO is deputed to degradation of the NMDA receptor co-agonist D-serine in human brain and the R199W substitution in DAAO was identified in a familial case of amyotrophic lateral sclerosis (ALS). A recent work reported that U87 glioblastoma cells ectopically expressing pLG72 showed a lower proliferation, produced superoxide radicals, induced SOD1 aggregation and decreased its activity. Because of the role of SOD1 in eliminating ROS species and its relevance in ALS we evaluated the link between pLG72 and SOD1 using both wild-type pLG72 and its R30K variant related to schizophrenia susceptibility. In vitro studies on recombinant proteins excluded the establishment of a stable complex and that pLG72 could affect SOD1 activity and stability. At cellular level, ectopic expression of pLG72 in glioblastoma U87 cells did not affect cell viability and ROS/superoxide production: only caspase activity (a marker of apoptosis) was slightly increased in cells expressing the R30K pLG72 variant. SOD1 and pLG72 did not colocalize in transfected U87 glioblastoma cells: pLG72 largely localised to mitochondria and SOD1 was largely cytosolic. Moreover, the ectopic expression of pLG72 appeared not to alter the expression of SOD1 and its aggregation. Altogether, the combination of biochemical and cellular studies allow to exclude that pLG72 modulates SOD1 function and aggregation, thus that it could play a role in ALS susceptibility.

Chlorella vulgaris supplementation effects on performances, oxidative stress and antioxidant genes expression in liver and ovaries of New Zealand White rabbits

Oxidative stress is an exclusive biochemical complication affecting reproduction; hence, dietary antioxidant supplementation for its attenuation is a required nutrition - reproduction improvement strategy. On this background, Chlorella vulgaris (a natural antioxidant) was supplemented to grower female rabbits to maturity. The rabbits were thirty-five in number randomly distributed into five experimental groups in a completely randomized design. Control group was fed only basal feed while treatment groups were fed diets containing 40 %, 60 %, 80 % and 100 % Chlorella vulgaris biomass as T1, T2, T3 and T4 respectively at 500 mg per animal body weight (kg) along with the basal feed daily. Performance records were obtained, blood was collected, and at the end uterus, ovaries and liver were removed from sacrificed animals for analysis. Serum, uterus and liver oxidative stress status were determined while RNA isolated from liver and ovaries samples were used for antioxidant genes expression analysis. Oxidative stress status and antioxidant enzymes activities were determined using chemical assays while antioxidant gene expression levels were determined using real-time quantitative PCR system. There was significant difference in feed intake (p < 0.014), final body weights (p < 0.008), empty carcass weights (p < 0.001) and commercial carcass weights (p < 0.001) of the rabbits as results of the microalgae supplementation. There was also significant difference in malondialdehyde (MDA) concentrations (p < 0.050), total antioxidant capacity (TAC) (p < 0.050) and protein carbonyl (PCO) concentrations (p < 0.050) due to the supplementation of the microalgae; in addition, supplementation of the microalgae significantly improved activities of superoxide dismutase (SOD) (p < 0.050), catalase (CAT) (p < 0.050) and reduced glutathione (GSH) concentration (p < 0.050). Furthermore, there was significant difference in relative expression of primary antioxidant genes sod1 (p < 0.050) and gpx1 (p < 0.050); however, there was no significant difference in relative expression of bre (p > 0.050) and ucp1 (p > 0.050). The study concluded from the outcomes stated above that supplementation of microalgae Chlorella vulgaris improved performances of rabbits through attenuation of oxidative stress, enhancement of antioxidant enzymes activities as well as up-regulation of primary antioxidant genes. Hence, it was recommended as dietary supplement for protection against oxidative stress and improved productivity in rabbits and other food producing mammalian species. In addition, further studies into assessment of its effects on expression of transcripts and immune modulation genes in rabbits and other animals is warranted as future studies in order to established its potential as beneficial nutraceutical for animals and human.