The Parkinson's disease gene PINK1 activates Akt via PINK1 kinase-dependent regulation of the phospholipid PI(3,4,5)P3

Spautin-1 promotes PINK1-PRKN-dependent mitophagy and improves associative learning capability in an alzheimer disease animal model

Spautin-1 is a well-known macroautophagy/autophagy inhibitor via suppressing the deubiquitinases USP10 and USP13 and promoting the degradation of the PIK3C3/VPS34-BECN1 complex, while its effect on selective autophagy remains poorly understood. Mitophagy is a selective form of autophagy for removal of damaged and superfluous mitochondria via the autophagy-lysosome pathway. Here, we report a surprising discovery that, while spautin-1 remains as an effective autophagy inhibitor, it promotes PINK1-PRKN-dependent mitophagy induced by mitochondrial damage agents. Mechanistically, spautin-1 facilitates the stabilization and activation of the full-length PINK1 at the outer mitochondrial membrane (OMM) via binding to components of the TOMM complex (TOMM70 and TOMM20), leading to the disruption of the mitochondrial import of PINK1 and prevention of PARL-mediated PINK1 cleavage. Moreover, spautin-1 induces neuronal mitophagy in Caenorhabditis elegans (C. elegans) in a PINK-1-PDR-1-dependent manner. Functionally, spautin-1 is capable of improving associative learning capability in an Alzheimer disease (AD) C. elegans model. In summary, we report a novel function of spautin-1 in promoting mitophagy via the PINK1-PRKN pathway. As deficiency of mitophagy is closely implicated in the pathogenesis of neurodegenerative disorders, the pro-mitophagy function of spautin-1 might suggest its therapeutic potential in neurodegenerative disorders such as AD.Abbreviations: AD, Alzheimer disease; ATG, autophagy related; BafA1, bafilomycin A1; CALCOCO2/NDP52, calcium binding and coiled-coil domain 2; CCCP, carbonyl cyanide m-chlorophenyl hydrazone; COX4/COX IV, cytochrome c oxidase subunit 4; EBSS, Earle's balanced salt; ECAR, extracellular acidification rate; GFP, green fluorescent protein; IA, isoamyl alcohol; IMM, inner mitochondrial membrane; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MMP, mitochondrial membrane potential; mtDNA, mitochondrial DNA; nDNA, nuclear DNA; O/A, oligomycin-antimycin; OCR, oxygen consumption rate; OMM, outer mitochondrial membrane; OPTN, optineurin; PARL, presenilin associated rhomboid like; PINK1, PTEN induced kinase 1; PRKN, parkin RBR E3 ubiquitin protein ligase; p-Ser65-Ub, phosphorylation of Ub at Ser65; TIMM23, translocase of inner mitochondrial membrane 23; TOMM, translocase of outer mitochondrial membrane; USP10, ubiquitin specific peptidase 10; USP13, ubiquitin specific peptidase 13; VAL, valinomycin; YFP, yellow fluorescent protein.

Insulin signalling regulates Pink1 mRNA localization via modulation of AMPK activity to support PINK1 function in neurons

Mitochondrial quality control failure is frequently observed in neurodegenerative diseases. The detection of damaged mitochondria by stabilization of PTEN-induced kinase 1 (PINK1) requires transport of Pink1 messenger RNA (mRNA) by tethering it to the mitochondrial surface. Here, we report that inhibition of AMP-activated protein kinase (AMPK) by activation of the insulin signalling cascade prevents Pink1 mRNA binding to mitochondria. Mechanistically, AMPK phosphorylates the RNA anchor complex subunit SYNJ2BP within its PDZ domain, a phosphorylation site that is necessary for its interaction with the RNA-binding protein SYNJ2. Notably, loss of mitochondrial Pink1 mRNA association upon insulin addition is required for PINK1 protein activation and its function as a ubiquitin kinase in the mitophagy pathway, thus placing PINK1 function under metabolic control. Induction of insulin resistance in vitro by the key genetic Alzheimer risk factor apolipoprotein E4 retains Pink1 mRNA at the mitochondria and prevents proper PINK1 activity, especially in neurites. Our results thus identify a metabolic switch controlling Pink1 mRNA localization and PINK1 activity via insulin and AMPK signalling in neurons and propose a mechanistic connection between insulin resistance and mitochondrial dysfunction.

PINK1-PTEN axis promotes metastasis and chemoresistance in ovarian cancer via non-canonical pathway

BACKGROUND

Ovarian cancer is commonly associated with a poor prognosis due to metastasis and chemoresistance. PINK1 (PTEN-induced kinase 1) is a serine/threonine kinase that plays a crucial part in regulating various physiological and pathophysiological processes in cancer cells.

METHODS

The ATdb database and "CuratedOvarianData" were used to evaluate the effect of kinases on ovarian cancer survival. The gene expression in ovarian cancer cells was detected by Western blot and quantitative real-time PCR. The effects of gene knockdown or overexpression in vitro were evaluated by wound healing assay, cell transwell assay, immunofluorescence staining, immunohistochemistry, and flow cytometry analysis. Mass spectrometry analysis, protein structure analysis, co-immunoprecipitation assay, nuclear-cytoplasmic separation, and in vitro kinase assay were applied to demonstrate the PINK1-PTEN (phosphatase and tensin homolog) interaction and the effect of this interaction. The metastasis experiments for ovarian cancer xenografts were performed in female BALB/c nude mice.

RESULTS

PINK1 was strongly associated with a poor prognosis in ovarian cancer patients and promoted metastasis and chemoresistance in ovarian cancer cells. Although the canonical PINK1/PRKN (parkin RBR E3 ubiquitin protein ligase) pathway showed weak effects in ovarian cancer, PINK1 was identified to interact with PTEN and phosphorylate it at Serine179. Remarkably, the phosphorylation of PTEN resulted in the inactivation of the phosphatase activity, leading to an increase in AKT (AKT serine/threonine kinase) activity. Moreover, PINK1-mediated phosphorylation of PTEN impaired the nuclear import of PTEN, thereby enhancing the cancer cells' ability to resist chemotherapy and metastasize.

CONCLUSIONS

PINK1 interacts with and phosphorylates PTEN at Serine179, resulting in the activation of AKT and the inhibition of PTEN nuclear import. PINK1 promotes ovarian cancer metastasis and chemotherapy resistance through the regulation of PTEN. These findings offer new potential therapeutic targets for ovarian cancer management.

LAR Downregulation Protects the Astrocytic U251 and Cocultured SH-SY5Y Cells in a Rotenone-Induced Parkinson's Disease Cell Model

Leukocyte common antigen-related protein tyrosine phosphatase (LAR) is a member of the protein tyrosine phosphatase family that serves as a key regulator of cellular survival. It is also involved in neurodevelopment and brain disorders. This study was designed to investigate the role of LAR in a cell-based model of Parkinson's disease (PD) in which U251 and SH-SY5Y cells were used as models of astrocytes and dopaminergic neurons, respectively. Cell viability, cell death, cell morphology, protein phosphorylation and expression, ATP levels, reactive oxygen species (ROS) generation, and mitochondrial membrane potential were analyzed in the wild-type (WT) and heterozygous LAR-knockout astrocytoma U251 cells to assess the cell state, signal transduction, and mitochondrial function. LAR downregulation showed a protective effect in rotenone-exposed U251 cells by increasing cell viability, reducing cell mortality, and restoring appropriate cellular morphology. LAR downregulation enhanced IGF-1R phosphorylation and downstream signal transduction as evidenced by increases in the Akt and GSK-3β phosphorylation, as well as the upregulation of NRF2 and HO-1. The downregulation of LAR also augmented DJ-1 levels in these cells. The enhanced Akt and GSK-3β phosphorylation contributed to a reduced Bax/Bcl2 ratio and suppressed apoptosis after rotenone exposure. Heterozygous LAR-knockout U251 cells exhibited higher mitochondrial function evidenced by increased mitochondrial membrane potential, ATP contents, and reduced ROS production compared to the WT cells following rotenone exposure. Further studies showed that the astrocytic protection mediated by the heterozygous knockout of LAR was associated with the activation of Akt. A specific Akt inhibitor, MK2206, reduced the cell viability, Akt and GSK3β phosphorylation, and HO-1 and NRF2 expression in U251 cells exposed to rotenone. Astrocytes provide structural and metabolic support to maintain neuronal health. Astrocytic glial cell-derived neurotrophic factor (GDNF) production is vital for dopaminergic neuron survival. Heterozygous LAR-knockout U251 cells produced higher amounts of GDNF than the WT cells. The SH-SY5Y cells cocultured with heterozygous LAR-knockout U251 cells exhibited greater viability than that of cells cocultured with WT U251 cells in response to rotenone. Together, these findings demonstrate that the heterozygous knockout of LAR in astrocytes can play a key role in protecting both astrocytic cells and cocultured neurons in a rotenone-induced cell-based model of PD. This neuroprotective effect is attributable to the augmentation of IGF1R-Akt-GDNF signaling and the maintenance of astrocytic mitochondrial function.

The synthetic TRPML1 agonist ML-SA1 rescues Alzheimer-related alterations of the endosomal-autophagic-lysosomal system

Abnormalities in the endosomal-autophagic-lysosomal (EAL) system are an early event in Alzheimer's disease (AD) pathogenesis. However, the mechanisms underlying these abnormalities are unclear. The transient receptor potential channel mucolipin 1(TRPML1, also known as MCOLN1), a vital endosomal-lysosomal Ca2+ channel whose loss of function leads to neurodegeneration, has not been investigated with respect to EAL pathogenesis in late-onset AD (LOAD). Here, we identify pathological hallmarks of TRPML1 dysregulation in LOAD neurons, including increased perinuclear clustering and vacuolation of endolysosomes. We reveal that induced pluripotent stem cell (iPSC)-derived human cortical neurons expressing APOE ε4, the strongest genetic risk factor for LOAD, have significantly diminished TRPML1-induced endolysosomal Ca2+ release. Furthermore, we found that blocking TRPML1 function in primary neurons by depleting the TRPML1 agonist PI(3,5)P2 via PIKfyve inhibition, recreated multiple features of EAL neuropathology evident in LOAD. This included increased endolysosomal Ca2+ content, enlargement and perinuclear clustering of endolysosomes, autophagic vesicle accumulation and early endosomal enlargement. Strikingly, these AD-like neuronal EAL defects were rescued by TRPML1 reactivation using its synthetic agonist ML-SA1. These findings implicate defects in TRPML1 in LOAD EAL pathogenesis and present TRPML1 as a potential therapeutic target.

Competing endogenous RNA (ceRNA) networks in Parkinson's disease: A systematic review

Parkinson's disease (PD) is a distinctive clinical syndrome with several causes and clinical manifestations. Aside from an infectious cause, PD is a rapidly developing neurological disorder with a global rise in frequency. Notably, improved knowledge of molecular pathways and the developing novel diagnostic methods may result in better therapy for PD patients. In this regard, the amount of research on ceRNA axes is rising, highlighting the importance of these axes in PD. CeRNAs are transcripts that cross-regulate one another via competition for shared microRNAs (miRNAs). These transcripts may be either coding RNAs (mRNAs) or non-coding RNAs (ncRNAs). This research used a systematic review to assess validated loops of ceRNA in PD. The Prisma guideline was used to conduct this systematic review, which entailed systematically examining the articles of seven databases. Out of 309 entries, forty articles met all criteria for inclusion and were summarized in the appropriate table. CeRNA axes have been described through one of the shared vital components of the axes, including lncRNAs such as NEAT1, SNHG family, HOTAIR, MALAT1, XIST, circRNAs, and lincRNAs. Understanding the multiple aspects of this regulatory structure may aid in elucidating the unknown causal causes of PD and providing innovative molecular therapeutic targets and medical fields.

Impairment of insulin signaling pathway PI3K/Akt/mTOR and insulin resistance induced AGEs on diabetes mellitus and neurodegenerative diseases: a perspective review

Insulin resistance is common in type 2 diabetes mellitus (T2DM), neurodegenerative diseases, cardiovascular diseases, kidney diseases, and polycystic ovary syndrome. Impairment in insulin signaling pathways, such as the PI3K/Akt/mTOR pathway, would lead to insulin resistance. It might induce the synthesis and deposition of advanced glycation end products (AGEs), reactive oxygen species, and reactive nitrogen species, resulting in stress, protein misfolding, protein accumulation, mitochondrial dysfunction, reticulum function, and metabolic syndrome dysregulation, inflammation, and apoptosis. It plays a huge role in various neurodegenerative diseases like Parkinson's disease, Alzheimer's disease, Huntington's disease, and Amyloid lateral sclerosis. In this review, we intend to focus on the possible effect of insulin resistance in the progression of neurodegeneration via the impaired P13K/Akt/mTOR signaling pathway, AGEs, and receptors for AGEs.

Single-cell transcriptomics of human iPSC differentiation dynamics reveal a core molecular network of Parkinson's disease

Parkinson's disease (PD) is the second-most prevalent neurodegenerative disorder, characterized by the loss of dopaminergic neurons (mDA) in the midbrain. The underlying mechanisms are only partly understood and there is no treatment to reverse PD progression. Here, we investigated the disease mechanism using mDA neurons differentiated from human induced pluripotent stem cells (hiPSCs) carrying the ILE368ASN mutation within the PINK1 gene, which is strongly associated with PD. Single-cell RNA sequencing (RNAseq) and gene expression analysis of a PINK1-ILE368ASN and a control cell line identified genes differentially expressed during mDA neuron differentiation. Network analysis revealed that these genes form a core network, members of which interact with all known 19 protein-coding Parkinson's disease-associated genes. This core network encompasses key PD-associated pathways, including ubiquitination, mitochondrial function, protein processing, RNA metabolism, and vesicular transport. Proteomics analysis showed a consistent alteration in proteins of dopamine metabolism, indicating a defect of dopaminergic metabolism in PINK1-ILE368ASN neurons. Our findings suggest the existence of a network onto which pathways associated with PD pathology converge, and offers an inclusive interpretation of the phenotypic heterogeneity of PD.

MicroRNAs in the pathophysiology of Alzheimer's disease and Parkinson's disease: an overview

Neurodegenerative diseases are characterized by a progressive loss of neurons of the central nervous system (CNS) and serve as a major cause of morbidity, mortality and functional dependence especially among the elderly. Despite extensive research and development efforts, the success rate of clinical pipelines has been very limited. However, microRNAs (miRs) have been proved to be of crucial importance in regulating intracellular pathways for various pathologic conditions including those of a neurodegenerative nature. There is ample evidence of altered levels of various miRs in clinical samples of Alzheimer's disease and Parkinson's disease patients with potentially major clinical implications. In the current review, we aim to summarize the relevant literature on the role of miRs in the pathophysiology of Alzheimer's disease (AD) and Parkinson's disease (PD) as the two globally predominant neurodegenerative conditions.

Role of Akt isoforms in neuronal insulin signaling and resistance

The aim of the present study was to determine the role of Akt isoforms in insulin signaling and resistance in neuronal cells. By silencing Akt isoforms individually and in pairs, in Neuro-2a and HT22 cells we observed that, in insulin-sensitive condition, Akt isoforms differentially reduced activation of AS160 and glucose uptake with Akt2 playing the major role. Under insulin-resistant condition, phosphorylation of all isoforms and glucose uptake were severely affected. Over-expression of individual isoforms in insulin-sensitive and resistant cells differentially reversed AS160 phosphorylation with concomitant reversal in glucose uptake indicating a compensatory role of Akt isoforms in controlling neuronal insulin signaling. Post-insulin stimulation Akt2 translocated to the membrane the most followed by Akt3 and Akt1, decreasing glucose uptake in the similar order in insulin-sensitive cells. None of the Akt isoforms translocated in insulin-resistant cells or high-fat-diet mediated diabetic mice brain cells. Based on our data, insulin-dependent differential translocation of Akt isoforms to the plasma membrane turns out to be the key factor in determining Akt isoform specificity. Thus, isoforms play parallel with predominant role by Akt2, and compensatory yet novel role by Akt1 and Akt3 to regulate neuronal insulin signaling, glucose uptake, and insulin-resistance.

Dysregulated phosphoinositide 3-kinase signaling in microglia: shaping chronic neuroinflammation

Microglia are integral mediators of innate immunity within the mammalian central nervous system. Typical microglial responses are transient, intending to restore homeostasis by orchestrating the removal of pathogens and debris and the regeneration of damaged neurons. However, prolonged and persistent microglial activation can drive chronic neuroinflammation and is associated with neurodegenerative disease. Recent evidence has revealed that abnormalities in microglial signaling pathways involving phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) may contribute to altered microglial activity and exacerbated neuroimmune responses. In this scoping review, the known and suspected roles of PI3K-AKT signaling in microglia, both during health and pathological states, will be examined, and the key microglial receptors that induce PI3K-AKT signaling in microglia will be described. Since aberrant signaling is correlated with neurodegenerative disease onset, the relationship between maladapted PI3K-AKT signaling and the development of neurodegenerative disease will also be explored. Finally, studies in which microglial PI3K-AKT signaling has been modulated will be highlighted, as this may prove to be a promising therapeutic approach for the future treatment of a range of neuroinflammatory conditions.

A novel multi-target strategy to attenuate the progression of Parkinson's disease by diamine hybrid AGE/ALE inhibitor

Instead of a conventional 'one-drug-one-target approach', this article presents a novel multi-target approach with a concept of trapping simultaneously as many detrimental factors as possible involved in the progression of Parkinson's disease. These factors include reactive carbonyl species, reactive oxygen species, Fe^3+/Cu²⁺ and ortho-quinones (o-quinone), in particular. Different from the known multi-target strategies for Parkinson's disease, it is a sort of 'vacuum cleaning' strategy. The new agent consists of reactive carbonyl species scavenging moiety and reactive oxygen species scavenging and metal chelating moiety linked by a spacer. Provided that the capacity of scavenging o-quinones is demonstrated, this type of agent can further broaden its potential therapeutic profile. In order to support this new hypothetical approach, a number of simple in vitro experiments are proposed.

An Emerging Role for Phosphoinositides in the Pathophysiology of Parkinson’s Disease

Recent data support an involvement of defects in homeostasis of phosphoinositides (PIPs) in the pathophysiology of Parkinson’s disease (PD). Genetic mutations have been identified in genes encoding for PIP-regulating and PIP-interacting proteins, that are associated with familial and sporadic PD. Many of these proteins are implicated in vesicular membrane trafficking, mechanisms that were recently highlighted for their close associations with PD. PIPs are phosphorylated forms of the membrane phospholipid, phosphatidylinositol. Their composition in the vesicle’s membrane of origin, as well as membrane of destination, controls vesicular membrane trafficking. We review the converging evidence that points to the involvement of PIPs in PD. The review describes PD- and PIP-associated proteins implicated in clathrin-mediated endocytosis and autophagy, and highlights the involvement of α-synuclein in these mechanisms.

Deciphering the dual role and prognostic potential of PINK1 across cancer types

Metabolic rewiring and deregulation of the cell cycle are hallmarks shared by many cancers. Concerted mutations in key tumor suppressor genes, such as PTEN, and oncogenes predispose cancer cells for marked utilization of resources to fuel accelerated cell proliferation and chemotherapeutic resistance. Mounting research has demonstrated that PTEN-induced putative kinase 1 (PINK1) acts as a pivotal regulator of mitochondrial homeostasis in several cancer types, a function that also extends to the regulation of tumor cell proliferative capacity. In addition, involvement of PINK1 in modulating inflammatory responses has been highlighted by recent studies, further expounding PINK1's multifunctional nature. This review discusses the oncogenic roles of PINK1 in multiple tumor cell types, with an emphasis on maintenance of mitochondrial homeostasis, while also evaluating literature suggesting a dual oncolytic mechanism based on PINK1's modulation of the Warburg effect. From a clinical standpoint, its expression may also dictate the response to genotoxic stressors commonly used to treat multiple malignancies. By detailing the evidence suggesting that PINK1 possesses distinct prognostic value in the clinical setting and reviewing the duality of PINK1 function in a context-dependent manner, we present avenues for future studies of this dynamic protein.

Silencing of UCA1 Protects Against MPP+-Induced Cytotoxicity in SK-N-SH Cells via Modulating KCTD20 Expression by Sponging miR-423-5p

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. Long noncoding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) has been implicated in PD development. Nevertheless, little insight has been gained on the mechanisms of UCA1 in PD pathogenesis. The levels of UCA1, miR-423-5p and potassium channel tetramerization domain containing 20 (KCTD20) were assessed by qRT-PCR and western blot. Cell viability was gauged by the CCK-8 assay, and cell apoptosis was detected by flow cytometry. Targeted relationships among UCA1, miR-423-5p and KCTD20 were verified by dual-luciferase reporter and RNA immunoprecipitation assays. Our data showed that MPP⁺ induced UCA1 expression in SK-N-SH cells. UCA1 silencing protected against MPP⁺-evoked cytotoxicity in SK-N-SH cells. UCA1 functioned as a miR-423-5p sponge, and the protective impact of UCA1 silencing on MPP⁺-evoked cytotoxicity was mediated by miR-423-5p. KCTD20 was a direct target of miR-423-5p, and miR-423-5p overexpression mitigated MPP⁺-triggered cell injury by down-regulating KCTD20. Furthermore, UCA1 regulated KCTD20 expression by acting as a sponge of miR-423-5p in SK-N-SH cells. Our study first identified that the silencing of UCA1 protected SK-N-SH cells from MPP⁺-evoked cytotoxicity at least in part by targeting the miR-423-5p/KCTD20 axis.

Fragmentation of the Golgi complex of dopaminergic neurons in human substantia nigra: New cytopathological findings in Parkinson's disease

Fragmentation of the Golgi ribbon is a common feature of Parkinson´s disease and other neurodegenerative diseases. This alteration could be the consequence of the anterograde and retrograde transport imbalance, α-synuclein aggregates, and/or cytoskeleton alterations. Most information on this process has been obtained from cellular and animal experimental models, and as such, there is little information available on human tissue. If the information on human tissue was available, it may help to understand the cytopathological mechanisms of this disease. In the present study, we analyzed the morphological characteristics of the Golgi complex of dopaminergic neurons in human samples of substantia nigra of control and Parkinson's disease patients. We measured the expression levels of putative molecules involved in Golgi fragmentation, including α-synuclein, tubulin, and Golgi-associated regulatory and structural proteins. We show that, as a consequence of the disease, the Golgi complex is fragmented into small stacks without vesiculation. We found that only a limited number of regulatory proteins are altered. Rab1, a small GTPase regulating endoplasmic reticulum-to-Golgi transport, is the most dramatically affected, being highly overexpressed in the surviving neurons. We found that the SNARE protein syntaxin 5 forms extracellular aggregates resembling the amyloid plaques characteristic of Alzheimer's disease. These findings may help to understand the cytopathology of Parkinson's disease.

Kill one or kill the many: interplay between mitophagy and apoptosis

Mitochondria are key players of cellular metabolism, Ca²⁺ homeostasis, and apoptosis. The functionality of mitochondria is tightly regulated, and dysfunctional mitochondria are removed via mitophagy, a specialized form of autophagy that is compromised in hereditary forms of Parkinson's disease. Through mitophagy, cells are able to cope with mitochondrial stress until the damage becomes too great, which leads to the activation of pro-apoptotic BCL-2 family proteins located on the outer mitochondrial membrane. Active pro-apoptotic BCL-2 proteins facilitate the release of cytochrome c from the mitochondrial intermembrane space (IMS) into the cytosol, committing the cell to apoptosis by activating a cascade of cysteinyl-aspartate specific proteases (caspases). We are only beginning to understand how the choice between mitophagy and the activation of caspases is determined on the mitochondrial surface. Intriguingly in neurons, caspase activation also plays a non-apoptotic role in synaptic plasticity. Here we review the current knowledge on the interplay between mitophagy and caspase activation with a special focus on the central nervous system.

Mitochondria-targeted magnolol inhibits OXPHOS, proliferation, and tumor growth via modulation of energetics and autophagy in melanoma cells

Introduction:

Melanoma is an aggressive form of skin cancer for which there are no effective drugs for prolonged treatment. The existing kinase inhibitor antiglycolytic drugs (B-Raf serine/threonine kinase or BRAF inhibitors) are effective for a short time followed by a rapid onset of drug resistance.

Presentation of case:

Here, we show that a mitochondria-targeted analog of magnolol, Mito-magnolol (Mito-MGN), inhibits oxidative phosphorylation (OXPHOS) and proliferation of melanoma cells more potently than untargeted magnolol. Mito-MGN also inhibited tumor growth in murine melanoma xenografts. Mito-MGN decreased mitochondrial membrane potential and modulated energetic and mitophagy signaling proteins.

Discussion:

Results indicate that Mito-MGN is significantly more potent than the FDA-approved OXPHOS inhibitor in inhibiting proliferation of melanoma cells.

Conclusion:

These findings have implications in the treatment of melanomas with enhanced OXPHOS status due to metabolic reprogramming or drug resistance.

Alterations in α-synuclein and PINK1 expression reduce neurite length and induce mitochondrial fission and Golgi fragmentation in midbrain neurons

Accumulation of α-synuclein is a pathological hallmark of Parkinson's disease (PD) and has been linked to reductions in neurite length and axonal degeneration of midbrain dopaminergic neurons. Mutations in SNCA, which encodes α-synuclein, and loss of function mutations in PTEN-induced putative kinase-1 (PINK1) cause familial PD. There is a need to identify the mechanisms by which α-synuclein overexpression and the loss of PINK1 induce neurodegeneration in PD. To do this, we employed rat ventral midbrain cultures to investigate the effects of overexpression of wildtype or mutant (A53T) α-synuclein, and of siRNA knockdown of PINK1, on neurite length and on mitochondrial and Golgi integrity. We found reduced neurite length and increased levels of both Golgi fragmentation and mitochondrial fission in response to overexpression of wildtype or mutant α-synuclein, and to PINK1 knockdown. Reductions in neurite length induced by these two PD risk genes were significantly correlated with increases in Golgi fragmentation and mitochondrial fission. Combined α-synuclein overexpression and PINK1 knockdown induced a greater reduction in neurite length and increase in Golgi fragmentation, than either alone. This study provides novel evidence that α-synuclein overexpression and PINK1 deletion converge to induce significant increases in Golgi fragmentation and mitochondrial fission in midbrain neurons, that are correlated with decreases in neurite length. This highlights the need for further studies on these converging mechanisms in dopaminergic neurodegeneration in PD.

First person – Rachel Furlong

First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Rachel Furlong is first author on ‘The Parkinson's disease gene PINK1 activates Akt via PINK1 kinase-dependent regulation of the phospholipid PI(3,4,5)P3’, published in JCS. Rachel is a PhD student in the labs of Prof. Cora O'Neill and Prof. Aideen Sullivan at University College Cork, Ireland, investigating why neurons die in neurodegenerative disease and potential methods to prevent this.