The role of microglial LRRK2 in manganese-induced inflammatory neurotoxicity via NLRP3 inflammasome and RAB10-mediated autophagy dysfunction

Therapeutic Effect of Padina arborescens Extract on a Cell System Model for Parkinson's Disease

Leucine-rich repeat kinase 2 (LRRK2) and α-synuclein are involved in the pathogenesis of Parkinson's disease. The activity of LRRK2 in microglial cells is associated with neuroinflammation, and LRRK2 inhibitors are crucial for alleviating this neuroinflammatory response. α-synuclein contributes to oxidative stress in the dopaminergic neuron and neuroinflammation through Toll-like receptors in microglia. In this study, we investigated the effect of the marine alga Padina arborescens on neuroinflammation by examining LRRK2 activation and the aggregation of α-synuclein. P. arborescens extract inhibits LRRK2 activity in vitro and decreases lipopolysaccharide (LPS)-induced LRRK2 upregulation in BV2, a mouse microglial cell line. Treatment with P. arborescens extract decreased tumor necrosis factor-α (TNF-α) gene expression by LPS through LRRK2 inhibition in BV2. It also attenuated TNF-α gene expression, inducible nitric oxide synthase, and the release of TNF-α and cellular nitric oxide in rat primary microglia. Furthermore, P. arborescens extract prevented rotenone (RTN)-induced oxidative stress in primary rat astrocytes and inhibited α-synuclein fibrilization in an in vitro assay using recombinant α-synuclein and in the differentiated human dopaminergic neuronal cell line SH-SY5Y (dSH). The extract increased lysosomal activity in dSH cells. In addition, P. arborescens extract slightly prolonged the lifespan of Caenorhabditis elegans, which was reduced by RTN treatment.

Signal Transduction Associated with Mn-induced Neurological Dysfunction

Manganese (Mn) is a heavy metal that occurs widely in nature and has a vital physiological role in growth and development. However, excessive exposure to Mn can cause neurological damage, especially cognitive dysfunction, such as learning disability and memory loss. Numerous studies on the mechanisms of Mn-induced nervous system damage found that this metal targets a variety of metabolic pathways, for example, endoplasmic reticulum stress, apoptosis, neuroinflammation, cellular signaling pathway changes, and neurotransmitter metabolism interference. This article reviews the latest research progress on multiple signaling pathways related to Mn-induced neurological dysfunction.

An Update on the Interplay between LRRK2, Rab GTPases and Parkinson's Disease

Over the last decades, research on the pathobiology of neurodegenerative diseases has greatly evolved, revealing potential targets and mechanisms linked to their pathogenesis. Parkinson's disease (PD) is no exception, and recent studies point to the involvement of endolysosomal defects in PD. The endolysosomal system, which tightly controls a flow of endocytosed vesicles targeted either for degradation or recycling, is regulated by a number of Rab GTPases. Their associations with leucine-rich repeat kinase 2 (LRRK2), a major causative and risk protein of PD, has also been one of the hot topics in the field. Understanding their interactions and functions is critical for unraveling their contribution to PD pathogenesis. In this review, we summarize recent studies on LRRK2 and Rab GTPases and attempt to provide more insight into the interaction of LRRK2 with each Rab and its relationship to PD.