REV-ERBα Mitigates Astrocyte Activation and Protects Dopaminergic Neurons from Damage.

Parkinson's disease (PD) is characterized by astrocyte activation and disruptions in circadian rhythm. Within the astrocyte population, two distinct reactive states exist: A1 and A2. A1 astrocytes are associated with neurotoxicity and inflammation, while A2 astrocytes exhibit neuroprotective functions. Our investigation focused on the role of REV-ERBα, a member of the nuclear receptor superfamily and a key regulator of the circadian clock, in astrocyte activation. We observed that REV-ERBα expression in A1 astrocytes was reduced to one-third of its normal level. Notably, activation of REV-ERBα prompted a transformation of astrocytes from A1 to A2. Mechanistically, REV-ERBα inhibition was linked to the classical NF-κB pathway, while it concurrently suppressed the STAT3 pathway. Furthermore, astrocytes with low REV-ERBα expression were associated with dopaminergic neurons apoptosis. Intriguingly, the opposite effect was observed when using a REV-ERBα agonist, which mitigated astrocyte activation and reduced dopaminergic neuron damage by 50%. In summary, our study elucidates the pivotal role of REV-ERBα in modulating astrocyte function and its potential implications in PD pathogenesis.

The biphasic role of Hspb1 on ferroptotic cell death in Parkinson's disease.

Rationale: Ferroptosis-driven loss of dopaminergic neurons plays a pivotal role in the pathogenesis of Parkinson's disease (PD). In PD patients, Hspb1 is commonly observed at abnormally high levels in the substantia nigra. The precise consequences of Hspb1 overexpression in PD, however, have yet to be fully elucidated. Methods: We used human iPSC-derived dopaminergic neurons and Coniferaldehyde (CFA)-an Nrf2 agonist known for its ability to cross the blood-brain barrier-to investigate the role of Hspb1 in PD. We examined the correlation between Hspb1 overexpression and Nrf2 activation and explored the transcriptional regulation of Hspb1 by Nrf2. Gene deletion techniques were employed to determine the necessity of Nrf2 and Hspb1 for CFA's neuroprotective effects. Results: Our research demonstrated that Nrf2 can upregulate the transcription of Hspb1 by directly binding to its promoter. Deletion of either Nrf2 or Hspb1 gene abolished the neuroprotective effects of CFA. The Nrf2-Hspb1 pathway, newly identified as a defense mechanism against ferroptosis, was shown to be essential for preventing neurodegeneration progression. Additionally, we discovered that prolonged overexpression of Hspb1 leads to neuronal death and that Hspb1 released from ruptured cells can trigger secondary cell death in neighboring cells, exacerbating neuroinflammatory responses. Conclusions: These findings highlight a biphasic role of Hspb1 in PD, where it initially provides neuroprotection through the Nrf2-Hspb1 pathway but ultimately contributes to neurodegeneration and inflammation when overexpressed. Understanding this dual role is crucial for developing therapeutic strategies targeting Hspb1 and Nrf2 in PD.

Protein tyrosine phosphatase receptor type O serves as a key regulator of insulin resistance-induced α-synuclein aggregation in Parkinson's disease.

Insulin resistance (IR) was found to be a critical element in the pathogenesis of Parkinson's disease (PD), facilitating abnormal α-synuclein (α-Syn) aggregation in neurons and thus promoting PD development. However, how IR contributes to abnormal α-Syn aggregation remains ill-defined. Here, we analyzed six PD postmortem brain transcriptome datasets to reveal module genes implicated in IR-mediated α-Syn aggregation. In addition, we induced IR in cultured dopaminergic (DA) neurons overexpressing α-Syn to identify IR-modulated differentially expressed genes (DEGs). Integrated analysis of data from PD patients and cultured neurons revealed 226 genes involved in α-Syn aggregation under IR conditions, of which 53 exhibited differential expression between PD patients and controls. Subsequently, we conducted an integrated analysis of the 53 IR-modulated genes employing transcriptome data from PD patients with different Braak stages and DA neuron subclasses with varying α-Syn aggregation scores. Protein tyrosine phosphatase receptor type O (PTPRO) was identified to be closely associated with PD progression and α-Syn aggregation. Experimental validation in a cultured PD cell model confirmed that both mRNA and protein of PTPRO were reduced under IR conditions, and the downregulation of PTPRO significantly facilitated α-Syn aggregation and cell death. Collectively, our findings identified PTPRO as a key regulator in IR-mediated α-Syn aggregation and uncovered its prospective utility as a therapeutic target in PD patients with IR.

Umbilical cord blood-derived exosomes attenuate dopaminergic neuron damage of Parkinson's disease mouse model.

BACKGROUND: Umbilical cord blood (UCB) is a rich source of multifunctional stem cells characterized by low immunogenicity. Recent research in the fields of aging and regenerative medicine has revealed the potential of human umbilical cord blood-derived exosomes (UCB-Exos) in promoting wound healing, anti-aging, and regeneration. However, their role in neurodegenerative diseases, specifically Parkinson's disease (PD), remains unexplored. This study investigates the potential therapeutic effects and underlying mechanisms of UCB-Exos on PD. METHODS: Large extracellular vesicles (LEv), Exos, and soluble fractions (SF) of human UCB plasma were extracted to investigate their effects on motor dysfunction of the MPTP-induced PD mouse model and identify the key components that improve PD symptoms. UCB-Exos were administered by the caudal vein to prevent or treat the PD mouse model. The motor function and pathological markers were detected. Differentially expressed gene and KEGG enrichment pathways were screened by transcriptome sequence. MN9D and SH-SY5Y cells were cultured and evaluated for cell viability, oxidative stress, cell cycle, and aging-related indexes by qRT-PCR, western blot, immunofluorescence, and flow cytometry. The protein expression level of the MAPK p38 and ERK1/2 signaling pathway was detected by western blot. RESULTS: We observed that LEv, Exos, and SF all exhibited potential in ameliorating motor dysfunction in MPTP-induced PD model mice, with UCB-Exos demonstrating the most significant effect. UCB-Exos showed comparable efficacy in preventing and treating motor dysfunction, cognitive decline, and substantia nigra pathological damage in PD mice. Further investigations revealed that UCB-Exos could potentially alleviate oxidative damage, aging and degeneration, and energy metabolism disorders in neurons. Transcriptome sequencing results corroborated that genes differentially expressed due to UCB-Exos were primarily enriched in the neuroactive ligand-receptor interaction, Dopaminergic synapse, and MAPK signaling pathway. We also observed that UCB-Exos significantly inhibited the hyperphosphorylation of the MAPK p38 and ERK1/2 signaling pathways both in vitro and in vivo. CONCLUSIONS: Our study provides a comprehensive evaluation of UCB-Exos on the neuroprotective effects and suggests that inhibition of hyperphosphorylation of MAPK p38 and ERK 1/2 signaling pathways by regulating transcription levels of HspB1 and Ppef2 may be the key mechanism for UCB-Exos to improve PD-related pathological features.

Dopaminergic neurons lacking Caspase-3 avoid apoptosis but undergo necrosis after MPTP treatment inducing a Galectin-3-dependent selective microglial phagocytic response.

Parkinson's Disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the Substantia nigra pars compacta (SNpc). Apoptosis is thought to play a critical role in the progression of PD, and thus understanding the effects of antiapoptotic strategies is crucial for developing potential therapies. In this study, we developed a unique genetic model to selectively delete Casp3, the gene encoding the apoptotic protein caspase-3, in dopaminergic neurons (TH-C3KO) and investigated its effects in response to a subacute regime of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration, which is known to trigger apoptotic loss of SNpc dopaminergic neurons. We found that Casp3 deletion did not protect the dopaminergic system in the long term. Instead, we observed a switch in the cell death pathway from apoptosis in wild-type mice to necrosis in TH-C3KO mice. Notably, we did not find any evidence of necroptosis in our model or in in vitro experiments using primary dopaminergic cultures exposed to 1-methyl-4-phenylpyridinium in the presence of pan-caspase/caspase-8 inhibitors. Furthermore, we detected an exacerbated microglial response in the ventral mesencephalon of TH-C3KO mice in response to MPTP, which mimicked the microglia neurodegenerative phenotype (MGnD). Under these conditions, it was evident the presence of numerous microglial phagocytic cups wrapping around apparently viable dopaminergic cell bodies that were inherently associated with galectin-3 expression. We provide evidence that microglia exhibit phagocytic activity towards both dead and stressed viable dopaminergic neurons through a galectin-3-dependent mechanism. Overall, our findings suggest that inhibiting apoptosis is not a beneficial strategy for treating PD. Instead, targeting galectin-3 and modulating microglial response may be more promising approaches for slowing PD progression.

Orphan receptor-GPR52 inverse agonist efficacy in ameliorating chronic stress-related deficits in reward motivation and phasic accumbal dopamine activity in mice.

Reward processing dysfunctions e.g., anhedonia, apathy, are common in stress-related neuropsychiatric disorders including depression and schizophrenia, and there are currently no established therapies. One potential therapeutic approach is restoration of reward anticipation during appetitive behavior, deficits in which co-occur with attenuated nucleus accumbens (NAc) activity, possibly due to NAc inhibition of mesolimbic dopamine (DA) signaling. Targeting NAc regulation of ventral tegmental area (VTA) DA neuron responsiveness to reward cues could involve either the direct or indirect-via ventral pallidium (VP)-pathways. One candidate is the orphan G protein-coupled receptor GPR52, expressed by DA receptor 2 NAc neurons that project to VP. In mouse brain-slice preparations, GPR52 inverse agonist (GPR52-IA) attenuated evoked inhibitory postsynaptic currents at NAc-VP neurons, which could disinhibit VTA DA neurons. A mouse model in which chronic social stress leads to reduced reward learning and effortful motivation was applied to investigate GPR52-IA behavioral effects. Control and chronically stressed mice underwent a discriminative learning test of tone-appetitive behavior-sucrose reinforcement: stress reduced appetitive responding and discriminative learning, and these anticipatory behaviors were dose-dependently reinstated by GPR52-IA. The same mice then underwent an effortful motivation test of operant behavior-tone-sucrose reinforcement: stress reduced effortful motivation and GPR52-IA dose-dependently restored it. In a new cohort, GRABDA-sensor fibre photometry was used to measure NAc DA activity during the motivation test: in stressed mice, reduced motivation co-occurred with attenuated NAc DA activity specifically to the tone that signaled reinforcement of effortful behavior, and GPR52-IA ameliorated both deficits. These findings: (1) Demonstrate preclinical efficacy of GPR52 inverse agonism for stress-related deficits in reward anticipation during appetitive behavior. (2) Suggest that GPR52-dependent disinhibition of the NAc-VP-VTA-NAc circuit, leading to increased phasic NAc DA signaling of earned incentive stimuli, could account for these clinically relevant effects.

Olfactory Projections to Locomotor Control Centers in the Sea Lamprey.

Although olfaction is well known to guide animal behavior, the neural circuits underlying the motor responses elicited by olfactory inputs are poorly understood. In the sea lamprey, anatomical evidence shows that olfactory inputs project to the posterior tuberculum (PT), a structure containing dopaminergic (DA) neurons homologous to the mammalian ventral tegmental area and the substantia nigra pars compacta. Olfactory inputs travel directly from the medial olfactory bulb (medOB) or indirectly through the main olfactory bulb and the lateral pallium (LPal). Here, we characterized the transmission of olfactory inputs to the PT in the sea lamprey, Petromyzon marinus. Abundant projections from the medOB were observed close to DA neurons of the PT. Moreover, electrophysiological experiments revealed that PT neurons are activated by both the medOB and LPal, and calcium imaging indicated that the olfactory signal is then relayed to the mesencephalic locomotor region to initiate locomotion. In semi-intact preparations, stimulation of the medOB and LPal induced locomotion that was tightly associated with neural activity in the PT. Moreover, PT neurons were active throughout spontaneously occurring locomotor bouts. Altogether, our observations suggest that the medOB and LPal convey olfactory inputs to DA neurons of the PT, which in turn activate the brainstem motor command system to elicit locomotion.

Transient Increases in Neural Oscillations and Motor Deficits in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms like tremors and bradykinesia. PD's pathology involves the aggregation of α-synuclein and loss of dopaminergic neurons, leading to altered neural oscillations in the cortico-basal ganglia-thalamic network. Despite extensive research, the relationship between the motor symptoms of PD and transient changes in brain oscillations before and after motor tasks in different brain regions remain unclear. This study aimed to investigate neural oscillations in both healthy and PD model mice using local field potential (LFP) recordings from multiple brain regions during rest and locomotion. The histological evaluation confirmed the significant dopaminergic neuron loss in the injection side in 6-OHDA lesioned mice. Behavioral tests showed motor deficits in these mice, including impaired coordination and increased forelimb asymmetry. The LFP analysis revealed increased delta, theta, alpha, beta, and gamma band activity in 6-OHDA lesioned mice during movement, with significant increases in multiple brain regions, including the primary motor cortex (M1), caudate-putamen (CPu), subthalamic nucleus (STN), substantia nigra pars compacta (SNc), and pedunculopontine nucleus (PPN). Taken together, these results show that the motor symptoms of PD are accompanied by significant transient increases in brain oscillations, especially in the gamma band. This study provides potential biomarkers for early diagnosis and therapeutic evaluation by elucidating the relationship between specific neural oscillations and motor deficits in PD.

Exploring the potential mechanism of atrazine-induced dopaminergic neurotoxicity based on integration strategy.

BACKGROUND: Atrazine (ATR), a commonly used herbicide, is linked to dopaminergic neurotoxicity, which may cause symptoms resembling Parkinson's disease (PD). This study aims to reveal the molecular regulatory networks responsible for ATR exposure and its effects on dopaminergic neurotoxicity based on an integration strategy. METHODS: Our approach involved network toxicology, construction of protein-protein interaction (PPI) networks, gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, as well as molecular docking techniques. Subsequently, we validated the predicted results in PC12 cells in vitro. RESULTS: An integrated analysis strategy indicating that 5 hub targets, including mitogen-activated protein kinase 3 (Mapk3), catalase (Cat), heme oxygenase 1 (Hmox1), tumor protein p53 (Tp53), and prostaglandin-endoperoxide synthase 2 (Ptgs2), may play a crucial role in ATR-induced dopaminergic injury. Molecular docking indicated that the 5 hub targets exhibited certain binding activity with ATR. Cell counting kit-8 (CCK8) results illustrated a dose-response relationship in PC12 cells. Real-time quantitative polymerase chain reaction (RT-qPCR) displayed notable changes in the expression of hub targets mRNA levels, with the exception of Mapk3. Western blotting results suggested that ATR treatment in PC12 cells resulted in an upregulation of the Cat, Hmox1, and p-Mapk3 protein expression levels while causing a downregulation in Tp53, Ptgs2, and Mapk3. CONCLUSION: Our findings indicated that 5 hub targets identified could play a vital role in ATR-induced dopaminergic neurotoxicity in PC12 cells. These results provide preliminary support for further investigation into the molecular mechanism of ATR-induced toxicity.

Modulation of human induced neural stem cell-derived dopaminergic neurons by DREADD reveals therapeutic effects on a mouse model of Parkinson's disease.

BACKGROUND: Stem cell-based therapy is a promising strategy for treating Parkinson's disease (PD) characterized by the loss of dopaminergic neurons. Recently, induced neural stem cell-derived dopaminergic precursor cells (iNSC-DAPs) have been emerged as a promising candidate for PD cell therapy because of a lower tumor-formation ability. Designer receptors exclusively activated by designer drugs (DREADDs) are useful tools for examining functional synaptic connections with host neurons. METHODS: DREADD knock-in human iNSCs to express excitatory hM3Dq and inhibitory hM4Di receptors were engineered by CRISPR. The knock-in iNSCs were differentiated into midbrain dopaminergic precursor cells (DAPs) and transplanted into PD mice. The various behavior test such as the Apomorphine-induced rotation test, Cylinder test, Rotarod test, and Open field test were assessed at 4, 8, or 12 weeks post-transplantation with or without the administration of CNO. Electrophysiology were performed to assess the integrated condition and modulatory function to host neurons. RESULTS: DREADD expressing iNSCs were constructed with normal neural stem cells characteristics, proliferation ability, and differentiation potential into dopaminergic neuorns. DAPs derived from DREADD expressing iNSC showed matched function upon administration of clozapine N-oxide (CNO) in vitro. The results of electrophysiology and behavioral tests of transplanted PD mouse models revealed that the grafts established synaptic connections with downstream host neurons and exhibited excitatory or inhibitory modulation in response to CNO in vivo. CONCLUSION: iNSC-DAPs are a promising candidate for cell replacement therapy for Parkinson's disease. Remote DREADD-dependent activation of iNSC-DAP neurons significantly enhanced the beneficial effects on transplanted mice with Parkinson's disease.

Cryogel microcarriers loaded with glial cell line-derived neurotrophic factor enhance the engraftment of primary dopaminergic neurons in a rat model of Parkinson's disease.

Objective.Cryogel microcarriers made of poly(ethylene glycol) diacrylate and 3-sulfopropyl acrylate have the potential to act as delivery vehicles for long-term retention of neurotrophic factors (NTFs) in the brain. In addition, they can potentially enhance stem cell-derived dopaminergic (DAergic) cell replacement strategies for Parkinson's disease (PD), by addressing the limitations of variable survival and poor differentiation of the transplanted precursors due to neurotrophic deprivation post-transplantation in the brain. In this context, to develop a proof-of-concept, the aim of this study was to determine the efficacy of glial cell line-derived NTF (GDNF)-loaded cryogel microcarriers by assessing their impact on the survival of, and reinnervation by, primary DAergic grafts after intra-striatal delivery in Parkinsonian rat brains.Approach.Rat embryonic day 14 ventral midbrain cells were transplanted into the 6-hydroxydopamine-lesioned striatum either alone, or with GDNF, or with unloaded cryogel microcarriers, or with GDNF-loaded cryogel microcarriers.Post-mortem, GDNF and tyrosine hydroxylase immunostaining were used to identify retention of the delivered GDNF within the implanted cryogel microcarriers, and to identify the transplanted DAergic neuronal cell bodies and fibres in the brains, respectively.Main results.We found an intact presence of GDNF-stained cryogel microcarriers in graft sites, indicating their ability for long-term retention of the delivered GDNF up to 4 weeks in the brain. This resulted in an enhanced survival (1.9-fold) of, and striatal reinnervation (density & volume) by, the grafted DAergic neurons, in addition to an enhanced sprouting of fibres within graft sites.Significance.This data provides an important proof-of-principle for the beneficial effects of neurotrophin-loaded cryogel microcarriers on engraftment of cells in the context of cell replacement therapy in PD. For clinical translation, further studies will be needed to assess the impact of cryogel microcarriers on the survival and differentiation of stem cell-derived DAergic precursors in Parkinsonian rat brains.

Tyrosine hydroxylase expression and neuronal loss in the male and female adolescent ventral tegmental area.

Adolescence is a critical period of development characterized by numerous behavioral and neuroanatomical changes. While studies of adolescent neurodevelopment typically compare adolescent age groups with young adults, there are fewer studies that assess developmental trajectories within the adolescent period. In the adolescent prefrontal cortex, some maturational changes take place linearly/chronologically, while others are associated specifically with pubertal onset. The adolescent ventral tegmental area (VTA), a primary source of forebrain dopamine, is relatively understudied during this period. In the present study, dopamine neuron number, total neuron number and tyrosine hydroxylase expression are assessed in the male and female rat VTA at three timepoints: postnatal day(P) 30 (pre-pubertal), P40 (post-pubertal for females, pre-pubertal for males) and P60 (post-pubertal). There was a non-significant trend for a reduction in total VTA neuron number between P30 and P60, but there was a significant reduction in dopamine neuron number across age. The expression of tyrosine hydroxylase did not change with age. However, in a second cohort of subjects, brain tissue was collected pre-pubertal, from recently post-pubertal males and females, and young adults. In this cohort, there was a sex-specific and transient decrease in tyrosine hydroxylase expression in recently post-pubertal males. These results suggest a selective pruning of VTA dopamine cells between early adolescence and young adulthood, while pubertal onset may coincide with a rapid maturation of these neurons. These findings may have implications for psychiatric disorders associated with dopamine dysfunction that tend to manifest during adolescence.

Dopaminergic system and neurons: Role in multiple neurological diseases.

The dopaminergic system is a complex and powerful neurotransmitter system in the brain. It plays an important regulatory role in motivation, reward, cognition, and motor control. In recent decades, research in the field of the dopaminergic system and neurons has increased exponentially and is gradually becoming a point of intervention in the study and understanding of a wide range of neurological diseases related to human health. Studies have shown that the dopaminergic system and neurons are involved in the development of many neurological diseases (including, but not limited to Parkinson's disease, schizophrenia, depression, attention deficit hyperactivity disorder, etc.) and that dopaminergic neurons either have too much stress or too weak function in the dopaminergic system can lead to disease. Therefore, targeting dopaminergic neurons is considered key to treating these diseases. This article provides a comprehensive review of the dopaminergic system and neurons in terms of brain region distribution, physiological function and subtypes of dopaminergic neurons, as well as the role of the dopaminergic system and neurons in a variety of diseases.

Role of ventral tegmental area dopamine neurons in fear memory retention in post-traumatic stress disorder model rats.

Ventral tegmental area (VTA) dopamine (DA) neurons have been found to substantially associate with post-traumatic stress disorder (PTSD) pathology, however, whether and how these DA neurons affect fear memory management in PTSD individuals remains largely unknown. In this study, we utilized auditory conditioned foot-shock to evaluate the fear memory retrieval and retention characteristics in a single prolonged stress-induced PTSD rat model. We employed chemogenetic technology to specifically activate VTA DA neurons to examine the freezing behaviors responding to the conditioned stimuli. In vivo extracellular electrophysiological analyses were used to identify VTA DA neuronal firing alterations due to the chemogenetic activation. The results demonstrated that PTSD model rats showed comparable fear memory retrieval (Day 2 after the conditioned foot-shock), but significant enhancements in fear memory retention (Day 8 after the conditioned foot-shock), compared to normal control rats. Chemogenetic activation of VTA DA neurons markedly diminished the retention of fear memory in PTSD model rats, which appeared concomitantly with increases in the firing activities of the DA neurons. These findings revealed that PTSD induced the persistence of fear memory, which could be attenuated by activation of VTA DA neurons. It is presumed that VTA dopaminergic signals may serve as a prospective option for PTSD treatment.

Upregulation of γ-synuclein in the prefrontal cortex and hippocampus following dopamine depletion: A study using the striatal 6-hydroxydopamine hemiparkinsonian rat model.

Synucleins, including α-synuclein (α-syn), ß-syn, and γ-syn, have been implicated in various synucleinopathies, notably Parkinson's disease (PD), which has generated increased interest in understanding their roles. Although α-syn and ß-syn have contrasting neuropathological consequences, the precise role of γ-syn remains unclear. This study validated non-motor symptoms, specifically anxiety-like behavior, along with the degradation of dopaminergic (DAergic) neurons in the nigrostriatal system and DAergic neurites in the prefrontal cortex and hippocampus of rats infused with striatal 6-hydroxydopamine (6-OHDA). Our study further investigated the alterations in γ-syn expression levels in the prefrontal cortices and hippocampi of these 6-OHDA-treated rats, aiming to establish foundational insights into the neuropathophysiology of DA depletion, a central feature of PD. Our findings revealed a significant increase in the expression of γ-syn mRNA and protein in these brain regions, in contrast to unaltered α- and ß-syn expression levels. This suggests a distinct role of γ-syn within the neurobiological milieu under conditions of DA deficiency. Overall, our data shed light on the neurobiological changes observed in the hemiparkinsonian rat model induced with 6-OHDA, underscoring the potential significance of γ-syn in PD pathology.

Exploring the neuroprotective potential of Nrf2-pathway activators against annonacin toxicity.

Modulation of the Nrf2 pathway, a master regulator of the antioxidant response and cellular metabolism, has been suggested as a promising therapeutic strategy in tauopathies, a heterogeneous group of neurodegenerative disorders characterized by intracellular proteinaceous inclusions of abnormally phosphorylated tau. Here, we explored the neuroprotective potential of different Nrf2-pathway activators in human immortalized dopaminergic neurons against annonacin-induced toxicity, a mitochondrial inhibitor associated with a PSP-like syndrome and capable of mimicking tauopathy-like features. Interestingly, we observed heterogenous and compound-dependent neuroprotective effects among the different Nrf2-pathway activators. With the exception of Fyn inhibitors, all the selected Nrf2-pathway activators improved cell viability and the oxidative status, and reduced the annonacin-induced tau hyperphosphorylation and neurite degeneration, particularly the p62-activators. However, improvement of the impaired mitochondrial function was only observed by the Bach-1 inhibitor. Surprisingly, we found evidence that ezetimibe, an approved drug for hypercholesterolemia, prevents the transcriptional upregulation of 4R-tau triggered by annonacin insult. Overall, our results suggest that the neuroprotective effects of the Nrf2-pathway activators against annonacin toxicity may rely on the specific mechanism of action, intrinsic to each compound, and possibly on the concomitant modulation of additional signaling pathways. Further research will be needed to fully understand how synergistic modulation of metabolic adaptation and cell survival can be exploit to develop new therapeutical strategies for tauopathies and eventually other neurodegenerative diseases.

Pathological characteristics of axons and alterations of proteomic and lipidomic profiles in midbrain dopaminergic neurodegeneration induced by WDR45-deficiency.

BACKGROUND: Although WD repeat domain 45 (WDR45) mutations have been linked to ß -propeller protein-associated neurodegeneration (BPAN), the precise molecular and cellular mechanisms behind this disease remain elusive. This study aims to shed light on the impacts of WDR45-deficiency on neurodegeneration, specifically axonal degeneration, within the midbrain dopaminergic (DAergic) system. We hope to better understand the disease process by examining pathological and molecular alterations, especially within the DAergic system. METHODS: To investigate the impacts of WDR45 dysfunction on mouse behaviors and DAergic neurons, we developed a mouse model in which WDR45 was conditionally knocked out in the midbrain DAergic neurons (WDR45cKO). Through a longitudinal study, we assessed alterations in the mouse behaviors using open field, rotarod, Y-maze, and 3-chamber social approach tests. We utilized a combination of immunofluorescence staining and transmission electron microscopy to examine the pathological changes in DAergic neuron soma and axons. Additionally, we performed proteomic and lipidomic analyses of the striatum from young and aged mice to identify the molecules and processes potentially involved in the striatal pathology during aging. Further more, primary midbrain neuronal culture was employed to explore the molecular mechanisms leading to axonal degeneration. RESULTS: Our study of WDR45cKO mice revealed a range of deficits, including impaired motor function, emotional instability, and memory loss, coinciding with the profound reduction of midbrain DAergic neurons. The neuronal loss, we observed massive axonal enlargements in the dorsal and ventral striatum. These enlargements were characterized by the accumulation of extensively fragmented tubular endoplasmic reticulum (ER), a hallmark of axonal degeneration. Proteomic analysis of the striatum showed that the differentially expressed proteins were enriched in metabolic processes. The carbohydrate metabolic and protein catabolic processes appeared earlier, and amino acid, lipid, and tricarboxylic acid metabolisms were increased during aging. Of note, we observed a tremendous increase in the expression of lysophosphatidylcholine acyltransferase 1 (Lpcat1) that regulates phospholipid metabolism, specifically in the conversion of lysophosphatidylcholine (LPC) to phosphatidylcholine (PC) in the presence of acyl-CoA. The lipidomic results consistently suggested that differential lipids were concentrated on PC and LPC. Axonal degeneration was effectively ameliorated by interfering Lpcat1 expression in primary cultured WDR45-deficient DAergic neurons, proving that Lpcat1 and its regulated lipid metabolism, especially PC and LPC metabolism, participate in controlling the axonal degeneration induced by WDR45 deficits. CONCLUSIONS: In this study, we uncovered the molecular mechanisms underlying the contribution of WDR45 deficiency to axonal degeneration, which involves complex relationships between phospholipid metabolism, autophagy, and tubular ER. These findings greatly advance our understanding of the fundamental molecular mechanisms driving axonal degeneration and may provide a foundation for developing novel mechanistically based therapeutic interventions for BPAN and other neurodegenerative diseases.

Novel Therapeutic Horizons: SNCA Targeting in Parkinson's Disease.

Alpha-synuclein (αSyn) aggregates are the primary component of Lewy bodies, which are pathological hallmarks of Parkinson's disease (PD). The toxicity of αSyn seems to increase with its elevated expression during injury, suggesting that therapeutic approaches focused on reducing αSyn burden in neurons could be beneficial. Additionally, studies have shown higher levels of SNCA mRNA in the midbrain tissues and substantia nigra dopaminergic neurons of sporadic PD post-mortem brains compared to controls. Therefore, the regulation of SNCA expression and inhibition of αSyn synthesis could play an important role in the pathogenesis of injury, resulting in an effective treatment approach for PD. In this context, we summarized the most recent and innovative strategies proposed that exploit the targeting of SNCA to regulate translation and efficiently knock down cytoplasmatic levels of αSyn. Significant progress has been made in developing antisense technologies for treating PD in recent years, with a focus on antisense oligonucleotides and short-interfering RNAs, which achieve high specificity towards the desired target. To provide a more exhaustive picture of this research field, we also reported less common but highly innovative strategies, including small molecules, designed to specifically bind 5'-untranslated regions and, targeting secondary nucleic acid structures present in the SNCA gene, whose formation can be modulated, acting as a transcription and translation control. To fully describe the efficiency of the reported strategies, the effect of αSyn reduction on cellular viability and dopamine homeostasis was also considered.

Regulation of TIR-1/SARM-1 by miR-71 Protects Dopaminergic Neurons in a C. elegans Model of LRRK2-Induced Parkinson's Disease.

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by symptoms such as bradykinesia, resting tremor, and rigidity, primarily driven by the degradation of dopaminergic (DA) neurons in the substantia nigra. A significant contributor to familial autosomal dominant PD cases is mutations in the LRRK2 gene, making it a primary therapeutic target. This study explores the role of microRNAs (miRNAs) in regulating the proteomic stress responses associated with neurodegeneration in PD using C. elegans models. Our focus is on miR-71, a miRNA known to affect stress resistance and act as a pro-longevity factor in C. elegans. We investigated miR-71's function in C. elegans models of PD, where mutant LRRK2 expression correlates with dopaminergic neuronal death. Our findings reveal that miR-71 overexpression rescues motility defects and slows dopaminergic neurodegeneration in these models, suggesting its critical role in mitigating the proteotoxic effects of mutant LRRK2. Conversely, miR-71 knockout exacerbates neuronal death caused by mutant LRRK2. Additionally, our data indicate that miR-71's neuroprotective effect involves downregulating the toll receptor domain protein tir-1, implicating miR-71 repression of tir-1 as vital in the response to LRRK2-induced proteotoxicity. These insights into miR-71's role in C. elegans models of PD not only enhance our understanding of molecular mechanisms in neurodegeneration but also pave the way for potential research into human neurodegenerative diseases, leveraging the conservation of miRNAs and their targets across species.

Opposite regulation by L-DOPA receptor GPR143 of the long and short forms of the dopamine D2 receptors.

Dopamine (DA) D2 receptors (D2Rs) have 2 isoforms, a long form (D2L) and a short form (D2S). D2L is predominantly postsynaptic in the striatal medium spiny neurons and cholinergic interneurons. D2S is principally presynaptic autoreceptors in the nigrostriatal DA neurons. Recently, we demonstrated that L-3,4-dihydroxyphenylalanine (L-DOPA) augments D2L function through the coupling between D2L and GPR143, a receptor of L-DOPA that was originally identified as the gene product of ocular albinism 1. Here we show that GPR143 modifies the functions of D2L and D2S in an opposite manner. Haloperidol-induced catalepsy was attenuated in DA neuron-specific Gpr143 gene-deficient (Dat-cre;Gpr143flox/y) mice, compared with wild-type (Wt) mice. Haloperidol increased in vivo DA release from the dorsolateral striatum, and this increase was augmented in Gpr143-/y mice compared with Wt mice. A D2R agonist quinpirole-induced increase in the phosphorylation of GSK3ß(pGSK3ß(S9)) was enhanced in Chinese hamster ovary (CHO) cells coexpressing D2L and GPR143 compared with cells expressing D2L alone, while it was suppressed in cells coexpressing D2S and GPR143 compared with D2S alone, suggesting that GPR143 differentially modifies D2R functions depending on its isoforms of D2L and D2S.