Extension of Health Span and Life Span in Drosophila by S107 Requires the calstabin Homologue FK506-BP2

Universal Prime Editing Therapeutic Strategy for RyR1-Related Myopathies: A Protective Mutation Rescues Leaky RyR1 Channel

RyR1-related myopathies (RyR1-RMs) include a wide range of genetic disorders that result from mutations in the RYR1 gene. Pathogenic variants lead to defective intracellular calcium homeostasis and muscle dysfunction. Fixing intracellular calcium leaks by stabilizing the RyR1 calcium channel has been identified as a promising therapeutic target. Gene therapy via prime editing also holds great promise as it can cure diseases by correcting genetic mutations. However, as more than 700 variants have been identified in the RYR1 gene, a universal treatment would be a more suitable solution for patients. Our investigation into the RyR1-S2843A mutation has yielded promising results. Using a calcium leak assay, we determined that the S2843A mutation was protective when combined with pathogenic mutations and significantly reduced the Ca2+ leak of the RyR1 channel. Our study demonstrated that prime editing can efficiently introduce the protective S2843A mutation. In vitro experiments using the RNA electroporation of the prime editing components in human myoblasts achieved a 31% introduction of this mutation. This article lays the foundation for a new therapeutic approach for RyR1-RM, where a unique once-in-a-lifetime prime editing treatment could potentially be universally applied to all patients with a leaky RyR1 channel.

Enhanced Age-Dependent Motor Impairment in Males of Drosophila melanogaster Modeling Spinocerebellar Ataxia Type 1 Is Linked to Dysregulation of a Matrix Metalloproteinase

Over the past two decades, Drosophila melanogaster has proven to be successful in modeling the polyglutamine (polyQ) (caused by CAG repeats) family of neurodegenerative disorders, including the faithful recapitulation of pathological features such as polyQ length-dependent formation of protein aggregates and progressive neuronal degeneration. In this study, pan-neuronal expression of human Ataxin-1 with long polyQ repeat of 82 amino acids was driven using an elav-GAL4 driver line. This would essentially model the polyQ disease spinocerebellar ataxia type 1 (SCA1). Longevity and behavioral analysis of male flies expressing human Ataxin-1 revealed compromised lifespan and accelerated locomotor activity deficits both in diurnal activity and negative geotaxis response compared to control flies. Interestingly, this decline in motor response was coupled to an enhancement of matrix metalloproteinase 1 (dMMP1) expression together with declining expression of extracellular matrix (ECM) fibroblast growth factor (FGF) signaling by hedgehog (Hh) and branchless (bnl) and a significant decrease in expression of survival motor neuron gene (dsmn) in old (30 d) flies. Taken together, our results indicate a role for dysregulation of matrix metalloproteinase in polyQ disease with consequent impact on ECM signaling factors, as well as SMN at the neuromuscular junction causing overt physiological and behavioral deficits.

Polysaccharides Extracted from Dendrobium officinale Grown in Different Environments Elicit Varying Health Benefits in Caenorhabditis elegans

Dendrobium officinale is one of the most widely used medicinal herbs, especially in Asia. In recent times, the polysaccharide content of D. officinale has garnered attention due to the numerous reports of its medicinal properties, such as anticancer, antioxidant, anti-diabetic, hepatoprotective, neuroprotective, and anti-aging activities. However, few reports of its anti-aging potential are available. Due to high demand, the wild D. officinale is scarce; hence, alternative cultivation methods are being employed. In this study, we used the Caenorhabditis elegans model to investigate the anti-aging potential of polysaccharides extracted from D. officinale (DOP) grown in three different environments; tree (TR), greenhouse (GH), and rock (RK). Our findings showed that at 1000 µg/mL, GH-DOP optimally extended the mean lifespan by 14% and the maximum lifespan by 25% (p < 0.0001). TR-DOP and RK-DOP did not extend their lifespan at any of the concentrations tested. We further showed that 2000 µg/mL TR-DOP, GH-DOP, or RK-DOP all enhanced resistance to H₂O₂-induced stress (p > 0.05, p < 0.01, and p < 0.01, respectively). In contrast, only RK-DOP exhibited resistance (p < 0.01) to thermal stress. Overall, DOP from the three sources all increased HSP-4::GFP levels, indicating a boost in the ability of the worms to respond to ER-related stress. Similarly, DOP from all three sources decreased α-synuclein aggregation; however, only GH-DOP delayed β-amyloid-induced paralysis (p < 0.0001). Our findings provide useful information on the health benefits of DOP and also provide clues on the best practices for cultivating D. officinale for maximum medicinal applications.

TM2D genes regulate Notch signaling and neuronal function in Drosophila

TM2 domain containing (TM2D) proteins are conserved in metazoans and encoded by three separate genes in each model organism species that has been sequenced. Rare variants in TM2D3 are associated with Alzheimer's disease (AD) and its fly ortholog almondex is required for embryonic Notch signaling. However, the functions of this gene family remain elusive. We knocked-out all three TM2D genes (almondex, CG11103/amaretto, CG10795/biscotti) in Drosophila and found that they share the same maternal-effect neurogenic defect. Triple null animals are not phenotypically worse than single nulls, suggesting these genes function together. Overexpression of the most conserved region of the TM2D proteins acts as a potent inhibitor of Notch signaling at the γ-secretase cleavage step. Lastly, Almondex is detected in the brain and its loss causes shortened lifespan accompanied by progressive motor and electrophysiological defects. The functional links between all three TM2D genes are likely to be evolutionarily conserved, suggesting that this entire gene family may be involved in AD.

Proteomic Analysis of Red Ginseng on Prolonging the Life Span of Male Drosophila melanogaster

Ginseng (Panax ginseng C. A. Mey.) is a traditional medicine that has been utilized for over 2000 years in Asia and shows varied pharmacological effects. Red ginseng (RG) is steamed and dried ginseng root and is considered to be more effective. Heating inactivates its catabolic enzymes and increases the activities of RG, which can improve the immune system, alleviate fatigue, and has anti-inflammatory effects and antioxidant activity. In addition, RG has a good anti-aging effect, but its mechanism is unclear. Senescence, a side-effect of normal developmental and metabolic processes, is a gradual decline in physiological integrity and function of the body. Senescence is usually associated with a variety of diseases, including neurodegenerative diseases and diabetes. Research on anti-aging and the prolongation of life span has always been a focus topic. In this study, we investigated the molecular mechanism of RG that results in prolonged the life span for male Drosophila melanogaster. Isobaric tag for relative and absolute quantitation (iTRAQ) was used to identify protein changes in an old male D. melanogaster treated with RG. The differential proteins were verified by qRT-PCR and western blotting. The results showed that 12.5 mg/ml RG prolonged its life span significantly. iTRAQ results showed that, compared to the control group, 32 upregulated proteins and 62 downregulated proteins displayed significantly differential expression in the RG group. In this study, we explored the pathways that RG may participate in that extend the life span of D. melanogaster, and the results showed that the PI3K/AKT/FoxO pathway was involved. In addition, 4E-BP increased and participated in the regulation of life span.

Sarcoplasmic reticulum Ca2+ decreases with age and correlates with the decline in muscle function in Drosophila

Sarcopenia, the loss of muscle mass and strength associated with age, has been linked to impairment of the cytosolic Ca2+ peak that triggers muscle contraction, but mechanistic details remain unknown. Here we explore the hypothesis that a reduction in sarcoplasmic reticulum (SR) Ca2+ concentration ([Ca2+]SR) is at the origin of this loss of Ca2+ homeostasis. We engineered Drosophila melanogaster to express the Ca2+ indicator GAP3 targeted to muscle SR, and we developed a new method to calibrate the signal into [Ca2+]SRin vivo [Ca2+]SR fell with age from ∼600 µM to 50 µM in close correlation with muscle function, which declined monotonically when [Ca2+]SR was <400 µM. [Ca2+]SR results from the pump-leak steady state at the SR membrane. However, changes in expression of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump and of the ryanodine receptor leak were too modest to explain the large changes seen in [Ca2+]SR Instead, these changes are compatible with increased leakiness through the ryanodine receptor as the main determinant of the [Ca2+]SR decline in aging muscle. In contrast, there were no changes in endoplasmic reticulum [Ca2+] with age in brain neurons.This article has an associated First Person interview with the first author of the paper.

Dynamics expression of DmFKBP12/Calstabin during embryonic early development of Drosophila melanogaster

Background

Calcium signaling are conserved from invertebrates to vertebrates and plays critical roles in many molecular mechanisms of embryogenesis and postnatal development. As a critical component of the signaling pathway, the RyR medicated calcium-induced calcium release signaling system, has been well studied along with their regulator FK506-binding protein 12 (FKBP12/Calstabin). Lack of FKBP12 is known to result in lethal cardiac dysfunction in mouse. However, precisely how FKBP12 is regulated and effects calcium signaling in Drosophila melanogaster remains largely unknown.

Results

In this study, we identified both temporal and localization changes in expression of DmFKBP12, a translational and transcriptional regulator of Drosophila RyR (DmRyR) and FKBP12, through embryonic development. DmFKBP12 is first expressed at the syncytial blastoderm stage and undergoes increased expression during the cellular blastoderm and early gastrulation stages. At late gastrulation, DmFKBP12 expression begins to decline until it reaches homeostasis, which it then maintains throughout the rest of development. Throughout these described changes in expression, DmFKBP12 mRNA remain stable, which indicates that protein dynamics are attributed to regulation at the mRNA to protein translation level. In addition to temporal changes in expression, dynamic expression profiles during Drosophila development also revealed DmFKBP12 localization. Although DmFKBP12 is distributed evenly between the anterior to posterior poles of the blastoderm egg, the protein is expressed more strongly in the cortex of the early Drosophila gastrula with the highest concentration found in the basement membrane of the cellular blastoderm. Fertilized egg, through the profile as under-membrane cortex distribution concentering onto basement at cellular blastoderm, to the profile as three-gem layer localization in primitive neuronal and digestion architecture of early Drosophila gastrula. By late gastrulation, DmFKBP12 is no longer identified in the yolk or lumen of duct structures and has relocated to the future brain (suboesophageal and supraesophageal ganglions), ventral nervous system, and muscular system. Throughout these changes in distribution, in situ DmFKBP12 mRNA monitoring detected equal distribution of DmFKBP12 mRNA, once again indicating that regulation of DmFKBP12 occurs at the translational level in Drosophila development.

Conclusion

As a critical regulator of the DmRyR-FKBP complex, DmFKBP12 expression in Drosophila fluctuates temporally and geographically with the formation of organ systems. These finding indicate that DmFKBP12 and RyR associated calcium signaling plays an essential role in the successful development of Drosophila melanogaster. Further study on the differences between mammalian RyR-FKBP12 and Drosophila DmRyR-FKBP12 can be exploited to develop safe pesticides.

Electronic supplementary material

The online version of this article (10.1186/s13578-019-0270-6) contains supplementary material, which is available to authorized users.

Transcriptomics of aged Drosophila motor neurons reveals a matrix metalloproteinase that impairs motor function

The neuromuscular junction (NMJ) is responsible for transforming nervous system signals into motor behavior and locomotion. In the fruit fly Drosophila melanogaster, an age-dependent decline in motor function occurs, analogous to the decline experienced in mice, humans, and other mammals. The molecular and cellular underpinnings of this decline are still poorly understood. By specifically profiling the transcriptome of Drosophila motor neurons across age using custom microarrays, we found that the expression of the matrix metalloproteinase 1 (dMMP1) gene reproducibly increased in motor neurons in an age-dependent manner. Modulation of physiological aging also altered the rate of dMMP1 expression, validating dMMP1 expression as a bona fide aging biomarker for motor neurons. Temporally controlled overexpression of dMMP1 specifically in motor neurons was sufficient to induce deficits in climbing behavior and cause a decrease in neurotransmitter release at neuromuscular synapses. These deficits were reversible if the dMMP1 expression was shut off again immediately after the onset of motor dysfunction. Additionally, repression of dMMP1 enzymatic activity via overexpression of a tissue inhibitor of metalloproteinases delayed the onset of age-dependent motor dysfunction. MMPs are required for proper tissue architecture during development. Our results support the idea that matrix metalloproteinase 1 is acting as a downstream effector of antagonistic pleiotropy in motor neurons and is necessary for proper development, but deleterious when reactivated at an advanced age.

Rejuvenation of the aged neuromuscular junction by exercise

Age-dependent declines in muscle function are observed across species. The loss of mobility resulting from the decline in muscle function represents an important health issue and a key determinant of quality of life for the elderly. It is believed that changes in the structure and function of the neuromuscular junction are important contributors to the observed declines in motor function with increased age. Numerous studies indicate that the aging muscle is an important contributor to the deterioration of the neuromuscular junction but the cellular and molecular mechanisms driving the degeneration of the synapse remain incompletely described. Importantly, growing data from both animal models and humans indicate that exercise can rejuvenate the neuromuscular junction and improve motor function. In this review we will focus on the role of muscle-derived neurotrophin signaling in the rejuvenation of the aged neuromuscular junction in response to exercise.