Pre-administration of BAX-inhibiting peptides decrease the loss of the nigral dopaminergic neurons in rats

Apoptotic cell death in disease-Current understanding of the NCCD 2023

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions. Here, the Nomenclature Committee on Cell Death (NCCD) gathered to critically summarize an abundant pre-clinical literature mechanistically linking the core apoptotic apparatus to organismal homeostasis in the context of disease.

Tumor necrosis factor α–induced protein 3 mediates inflammation and neuronal autophagy in Parkinson's disease via the NFκB and mTOR pathways

This study aimed to probe the function of tumor necrosis factor α-induced protein 3 (TNFAIP3) in the pathogenesis of Parkinson disease (PD) with its association with autophagy and inflammatory response. TNFAIP3 was reduced in the SN of PD patients (the GSE54282 dataset) and mice and in the MPP⁺-treated SK-N-SH cells. TNFAIP3 inhibited inflammatory response and enhanced autophagy, thereby alleviating PD in mice. NFκB and mTOR pathways were activated in the SN of PD mice and MPP⁺-treated cells. TNFAIP3 blocked the two pathways by preventing the p65 nuclear translocation and stabilizing DEPTOR, an endogenous inhibitor of mTOR. NFκB activator LPS and mTOR activator MHY1485 reversed the effects of TNFAIP3 on mitigation of injury in PD mice and in SK-N-SH cells induced with MPP⁺. Altogether, TNFAIP3 played a neuroprotective role in MPTP-induced mice by restricting NFκB and mTOR pathways.

Epigallocatechin-3-gallate: A phytochemical as a promising drug candidate for the treatment of Parkinson’s disease

Epigallocatechin 3-gallate (EGCG), an abundant polyphenolic component derived from green tea extract, possesses versatile bioactivities that can combat many diseases. During the last decade, EGCG was shown to be effective in experimental models of Parkinson’s disease (PD). Several experimental studies have suggested that it has pleiotropic neuroprotective effects, which has enhanced the appeal of EGCG as a therapeutic strategy in PD. In this review, we compiled recent updates and knowledge of the molecular mechanisms underlying the neuroprotective effects of EGCG in PD. We focused on the effects of EGCG on apoptosis, oxidative stress, inflammation, ferroptosis, modulation of dopamine production, and the aggregation of α-synuclein. The review highlights the pharmacological features of EGCG and its therapeutic implications in PD. Taken together, the accumulated data indicate that EGCG is a promising neuroprotective compound for the treatment of PD.

Cell Death-Osis of Dopaminergic Neurons and the Role of Iron in Parkinson's Disease

Significance: There is still no cure for neurodegenerative diseases, such as Parkinson's disease (PD). Current treatments are based on the attempt to reduce dopaminergic neuronal loss, and multidisciplinary approaches have been used to provide only a temporary symptoms' relief. In addition to the difficulties of drugs developed against PD to access the brain, the specificity of those inhibitory compounds could be a concern. This because neurons might degenerate by activating distinct signaling pathways, which are often initiated by the same stimulus. Recent Advances: Apoptosis, necroptosis, and ferroptosis were shown to significantly contribute to PD progression and, so far, are the main death programs described as capable to alter brain homeostasis. Their activation is characterized by different biochemical and morphological features, some of which might even share the same molecular players. Critical Issues: If there is a pathological need to engage, in PD, multiple death programs, sequentially or simultaneously, is not clear yet. Possibly the activation of apoptosis, necroptosis, and/or ferroptosis correlates to different PD stages and symptom severities. This would imply that the efficacy of therapeutic approaches against neuronal death might depend on the death program they target and the relevance of this death pathway on a specific PD phase. Future Directions: In this review, we describe the molecular mechanisms underlying the activation of apoptosis, necroptosis, and ferroptosis in PD. Understanding the interrelationship between different death pathways' activation in PD is of utmost importance for the development of therapeutic approaches against disease progression. Antioxid. Redox Signal. 35, 453-473.

MCL1 as a Therapeutic Target in Parkinson's Disease?

Dopamine neurons in the substantia nigra (SN) pars compacta are selectively lost during the progression of Parkinson's disease (PD). Recent work performed on the role of the Bcl2 family (highly specialized proteins which control cellular survival and death) in midbrain dopamine neurons has led to the identification of the Bcl2 factor Mcl1 as a weak link in the survival of these neurons. We hypothesize that the regulation of BCL2 proteins may explain this selective vulnerability, and may even provide a novel therapeutic opportunity - strengthening weak links such as MCL1 could result in a delay or complete abrogation of cell death during PD.

Balancing Apoptosis and Autophagy for Parkinson's Disease Therapy: Targeting BCL-2

Apoptosis and autophagy are important intracellular processes that maintain organism homeostasis and promote survival. Autophagy selectively degrades damaged cellular organelles and protein aggregates, while apoptosis removes damaged or aged cells. Maintaining a balance between autophagy and apoptosis is critical for cell fate, especially for long-lived cells such as neurons. Conversely, their imbalance is associated with neurodegenerative diseases such as Parkinson's disease (PD), which is characterized by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Restoring the balance between autophagy and apoptosis is a promising strategy for the treatment of PD. Some core proteins engage in cross talk between apoptosis and autophagy, including B cell lymphoma (BCL)-2 family members. This Review summarizes the role of BCL-2 members in the regulation of apoptosis and autophagy and discusses potential therapeutic approaches that target this balance for PD treatment.

Survival of midbrain dopamine neurons depends on the Bcl2 factor Mcl1

Mitochondria-dependent apoptosis plays an important role in the embryonic development of the midbrain dopaminergic system as well as in Parkinson’s disease. Central to mitochondria-dependent apoptosis is the Bcl2 family of apoptosis-regulating proteins. However, it was unclear which Bcl2 proteins are important for the survival of dopaminergic neurons. Here, we identify Mcl1 as a critical Bcl2 pro-survival factor in midbrain dopaminergic neurons. Using a chemical biology approach to inhibit various components of the apoptotic machinery in the dopaminergic MN9D cell line or the control neuroblastoma N2A cell line, we find that functional inhibition of Mcl1 with the high affinity small molecule inhibitor UMI-77 results in a rapid and dose-dependent loss of viability, selectively in dopaminergic cells. In-depth analysis of the apoptotic signaling pathway reveals that chemical inhibition of Mcl1 results in the activation of Bax, activation of cleaved caspase-3 and finally cell death. The dependence of mouse dopaminergic midbrain neurons on Mcl1 was confirmed using ex vivo slice cultures from Pitx3GFP/+ and wildtype mice. In mouse dopaminergic midbrain neurons positive for the midbrain dopaminergic marker Pitx3, or tyrosine hydroxylase, UMI-77 treatment caused a dramatic increase in cleaved caspase 3, indicating that Mcl1 activity is required for basal neuronal survival. Overall, our results suggest that Mcl1 is of critical importance to dopaminergic neurons and is a weak link in the chain controlling cellular survival. Boosting the pro-survival function of Mcl1 should be pursued as a therapeutic approach to augment the resilience of midbrain dopaminergic neurons to apoptotic stress in Parkinson’s disease.