Transferrin1 modulates rotenone-induced Parkinson's disease through affecting iron homeostasis in Drosophila melanogaster

Exploring the therapeutic potential of Chinese herbs on comorbid type 2 diabetes mellitus and Parkinson's disease: A mechanistic study

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) are chronic conditions that affect the aging population, with increasing prevalence globally. The rising prevalence of comorbidity between these conditions, driven by demographic shifts, severely impacts the quality of life of patients, posing a significant burden on healthcare resources. Chinese herbal medicine has been used to treat T2DM and PD for millennia. Pharmacological studies have demonstrated that medicinal herbs effectively lower blood glucose levels and exert neuroprotective effects, suggesting their potential as adjunctive therapy for concurrent management of T2DM and PD.

AIM OF THE STUDY

To elucidate the shared mechanisms underlying T2DM and PD, particularly focusing on the potential mechanisms by which medicinal herbs (including herbal formulas, single herbs, and active compounds) may treat these diseases, to provide valuable insights for developing therapeutics targeting comorbid T2DM and PD.

MATERIALS AND METHODS

Studies exploring the mechanisms underlying T2DM and PD, as well as the treatment of these conditions with medicinal herbs, were extracted from several electronic databases, including PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure (CNKI).

RESULTS

Numerous studies have shown that inflammation, oxidative stress, insulin resistance, impaired autophagy, gut microbiota dysbiosis, and ferroptosis are shared mechanisms underlying T2DM and PD mediated through the NLRP3 inflammasome, NF-κB, MAPK, Keap1/Nrf2/ARE, PI3K/AKT, AMPK/SIRT1, and System XC--GSH-GPX4 signaling pathways. Thirty-four medicinal herbs, including 2 herbal formulas, 4 single herbs, and 28 active compounds, have been reported to potentially exert anti-T2DM and anti-PD effects by targeting these shared mechanisms.

CONCLUSIONS

Traditional Chinese medicine effectively combats T2DM and PD through shared pathological mechanisms, highlighting their potential for application in treating these comorbid conditions.

β-asarone relieves Parkinson's disease through reducing intracellular Ca2+ in PINK1 mutant Drosophila melanogaster

β-asarone, an effective volatile oil component of Acorus chinensis, has been found to hold beneficial effects on Parkinson's disease (PD), but its mechanism remains incompletely understood. Drosophila melanogaster with PTEN induced kinase 1 (PINK1) mutations, a prototype PD model, was used in this study. We found that calcium chelation profoundly alleviated a spectrum of PD symptoms. Whereas, calcium supplementation made the case worse, suggesting accumulated calcium contributes to progression of PD. β-asarone administration decreased Ca2+ level in PD flies, accompanied by alleviated behavioral and neural defects. Further study demonstrated that β-asarone downregulated L-type Ca2+ channels (Dmca1D), which was increased in PD flies. Besides, β-asarone decreased expression of 1,4,5 - trisphosphate receptor (Itpr), which is responsible for calcium release from endoplasmic reticulum (ER). Knockdown of either Dmca1D or Itpr specifically in dopaminergic neurons alleviated behavioral and neural defects in PD flies. While overexpression of Itpr aggravated PD symptoms. The results indicated that increased intracellular calcium influx and release triggers dysregulation of calcium homeostasis in PD flies. And β-asarone prevents PD by restoring Ca2+ homeostasis. Overall, the study demonstrated that β-asarone can serve as a new prospective medication against PD or other diseases associated with dysregulation of Ca2+ homeostasis.

Mating modifies oxidative stress in the brain and confers protection against Parkinson's Disease in a Drosophila model

Mating exerts profound and multifaceted effects on the physiology of female insects, particularly influencing metabolic alterations and bolstering stress resilience. Drosophila melanogaster has emerged as an excellent model to investigate the mechanism of neurodegenerative diseases. However, interplay between mating and its impact on the Drosophila brain remains a tantalizing enigma, awaiting elucidation. Herein, we reported that mating significantly improved the climbing and jumping activity in mated females compared to the virgins in Drosophila. Mating also reduced oxidative stress in the brain. Based on the results, we found that, mated females exhibited better behavioral performance and fewer loss of dopaminergic (DA) neurons than unmated females in PINK1 RNAi flies, a well-established Parkinson's disease (PD) model. Further study demonstrated that mating led to decreased iron content in the brain, a process associated with decreased Transferrin 1 (Tsf1) and Malvolio (Mvl) and increased ferritin. Additionally, mating inhibited expression of Duox and Nox, two NADPH oxidases in Drosophila. Furthermore, Kr-h1, a transcription factor of JH, acted downstream of mating to regulate genes involved in iron metabolism and NADPH oxidases. Collectively, the findings suggested a pivotal role of mating in regulating iron metabolism and NADPH oxidases in the brain of Drosophila. Consequently, considering mating status is imperative in scientific research, particularly in the context of neurological disorders.

Copper overload exacerbates testicular aging mediated by lncRNA:CR43306 deficiency through ferroptosis in Drosophila

Testicular aging manifests as impaired spermatogenesis and morphological alterations in Drosophila. Nonetheless, the comprehensive molecular regulatory framework remains largely undisclosed. This investigation illustrates the impact of copper overload on testicular aging and underscores the interplay between copper overload and lncRNA. Copper overload triggers Cuproptosis through the mitochondrial TCA cycle, facilitating intracellular interactions with Ferroptosis, thereby governing testicular aging. Dysfunction of lncRNA:CR43306 also contributes to testicular aging in Drosophila, emphasizing the significance of lncRNA:CR43306 as a novel aging-associated lncRNA. Moreover, copper overload exacerbates spermatid differentiation defects mediated by lncRNA:CR43306 deficiency through oxidative stress, copper, and iron transport. Therapeutically, Ferrostatin-1 and Resveratrol emerge as potential remedies for addressing testicular aging. This study offers perspectives on the regulatory mechanisms involving copper overload and lncRNA:CR43306 deficiency in the context of testicular aging.

Inhibition of ferroptosis underlies EGCG mediated protection against Parkinson's disease in a Drosophila model

Ferroptosis, a new type of cell death accompanied by iron accumulation and lipid peroxidation, is implicated in the pathology of Parkinson's disease (PD), which is a prevalent neurodegenerative disorder that primarily occurred in the elderly population. Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea with known neuroprotective effects in PD patients. But whether EGCG-mediated neuroprotection against PD involves regulation of ferroptosis has not been elucidated. In this study, we established a PD model using PINK1 mutant Drosophila. Iron accumulation, lipid peroxidation and decreased activity of GPX, were detected in the brains of PD flies. Additionally, phenotypes of PD, including behavioral defects and dopaminergic neurons loss, were ameliorated by ferroptosis inhibitor ferrostatin-1 (Fer-1). Notably, the increased iron level, lipid peroxidation and decreased GPX activity in the brains of PD flies were relieved by EGCG. We found that EGCG exerted neuroprotection mainly by restoring iron homeostasis in the PD flies. EGCG inhibited iron influx by suppressing Malvolio (Mvl) expression and simultaneously promoted the upregulation of ferritin, the intracellular iron storage protein, leading to a reduction in free iron ions. Additionally, EGCG downregulated the expression of Duox and Nox, two NADPH oxidases that produce reactive oxygen species (ROS) and increased SOD enzyme activity. Finally, modulation of intracellular iron levels or regulation of oxidative stress by genetic means exerted great influence on PD phenotypes. As such, the results demonstrated that ferroptosis has a role in the established PD model. Altogether, EGCG has therapeutic potentials for treating PD by targeting the ferroptosis pathway, providing new strategies for the prevention and treatment of PD and other neurodegenerative diseases.

Neurotoxic and behavioral deficit in Drosophila melanogaster co-exposed to rotenone and iron

Exposure to environmental toxicants has been linked with the onset of different neurodegenerative diseases in animals and humans. Here, we evaluated the toxic effects of co-exposure to iron and rotenone at low concentrations in Drosophila melanogaster. Adult wild-type flies were orally exposed to rotenone (50.0 µM) and ferrous sulfate (FeSO₄; 1.0 and 10.0 µM) through the diet for 10 days. Thereafter, we evaluated markers of oxidative damage (Hydrogen Peroxide (H₂O₂), Nitric Oxide (NO), Protein Carbonyl, and malondialdehyde (MDA)), antioxidant status (catalase, Glutathione S-Transferase (GST), Total Thiol (T-SH) and Non-protein Thiol (NPSH), neurotransmission (monoamine oxidase; MAO and acetylcholinesterase, AChE) and mitochondrial respiration. The results indicated that flies fed rotenone and FeSO₄ had impaired locomotion, reduced survival rate, and AChE activity with a corresponding increase in MAO activity when compared with the control (p < 0.05). Furthermore, rotenone and FeSO₄ significantly decreased the antioxidant status with a concurrent accumulation of NO, MDA, and H₂O₂. Additionally, the activity of complex 1 and mitochondria bioenergetic capacity was compromised in the flies. These findings suggest that the combination of rotenone and FeSO₄ elicited a possible synergistic toxic response in the flies and therefore provided further insights on the use of D. melanogaster in toxicological studies.

Phenotypic analyses, protein localization, and bacteriostatic activity of Drosophila melanogaster transferrin-1

Transferrin-1 (Tsf1) is an extracellular insect protein with a high affinity for iron. The functions of Tsf1 are still poorly understood; however, Drosophila melanogaster Tsf1 has been shown to influence iron distribution in the fly body and to protect flies against some infections. The goal of this study was to better understand the physiological functions of Tsf1 in D. melanogaster by 1) investigating Tsf1 null phenotypes, 2) determining tissue-specific localization of Tsf1, 3) measuring the concentration of Tsf1 in hemolymph, 4) testing Tsf1 for bacteriostatic activity, and 5) evaluating the effect of metal and paraquat treatments on Tsf1 abundance. Flies lacking Tsf1 had more iron than wild-type flies in specialized midgut cells that take up iron from the diet; however, the absence of Tsf1 had no effect on the iron content of whole midguts, fat body, hemolymph, or heads. Thus, as previous studies have suggested, Tsf1 appears to have a minor role in iron transport. Tsf1 was abundant in hemolymph from larvae (0.4 μM), pupae (1.4 μM), adult females (4.4 μM) and adult males (22 μM). Apo-Tsf1 at 1 μM had bacteriostatic activity whereas holo-Tsf1 did not, suggesting that Tsf1 can inhibit microbial growth by sequestering iron in hemolymph and other extracellular environments. This hypothesis was supported by detection of secreted Tsf1 in tracheae, testes and seminal vesicles. Colocalization of Tsf1 with an endosome marker in oocytes suggested that Tsf1 may provide iron to developing eggs; however, eggs from mothers lacking Tsf1 had the same amount of iron as control eggs, and they hatched at a wild-type rate. Thus, the primary function of Tsf1 uptake by oocytes may be to defend against infection rather than to provide eggs with iron. In beetles, Tsf1 plays a role in protection against oxidative stress. In contrast, we found that flies lacking Tsf1 had a typical life span and greater resistance to paraquat-induced oxidative stress. In addition, Tsf1 abundance remained unchanged in response to ingestion of iron, cadmium or paraquat or to injection of iron. These results suggest that Tsf1 has a limited role in protection against oxidative stress in D. melanogaster.

Methods to Assay the Behavior of Drosophila melanogaster for Toxicity Study

Drosophila melanogaster, the fruit fly, has been widely used in biological investigation as an invertebrate alternative to mammals for its various advantages compared to other model organisms, which include short life cycle, easy handling, high prolificacy, and great availability of substantial genetic information. The behavior of Drosophila melanogaster is closely related to its growth, which can reflect the physiological conditions of Drosophila. We have optimized simple and robust behavioral assays for determining the larvae survival, adult climbing ability (mobility assay), reproductive behavior, and lifespan of Drosophila. In this chapter, we present the step-by-step detailed method for studying Drosophila behavior.

Determination of Metal Content in Drosophila melanogaster During Metal Exposure

Trace metal elements, such as zinc, iron, copper, and manganese, play catalytic or structural roles in many enzymes and numerous proteins, and accordingly, contribute to a variety of fundamental biological processes. During the past decade, the fruit fly (Drosophila melanogaster) has become an important model organism for elucidating metal homeostasis in metazoan. We have been using Drosophila as a model to study metal metabolism for many years and have optimized simple and robust assays for determining the metal content in Drosophila, such as inductively coupled plasma mass spectrometry (ICP-MS), the activity assay of enzymes dependent on metals, and staining metal ions in tissues of Drosophila. In this chapter, we present the step-by-step detailed methods for detecting the metal content in Drosophila melanogaster during metal toxicity study.