IU Indianapolis ScholarWorks :: Browsing by Author "Lasagna-Reeves, Cristian"

Browsing by Author "Lasagna-Reeves, Cristian"

Now showing 1 - 9 of 9

Contributions of the Presynaptic Protein Bassoon to Tau Pathogenesis and Neurodegeneration
(2024-05) Patel, Henika Sanjaybhai; Oblak, Adrian; Lasagna-Reeves, Cristian; McKinzie, David; Kim, Jungsu; Webb, Ian; Murray, Melissa
Neurodegenerative tauopathies, characterized by the aggregation of misfolded tau protein, pose a significant clinical and scientific challenge. A high-molecular-weight (HMW) tau species is known to be involved in spreading tau pathology. However, the nature and composition of this species remain elusive, hindering targeted interventions. There are four main chapters in this dissertation. The first chapter highlights the existing knowledge about tau and its role in neurodegenerative tauopathies and discusses the possible contribution of protein interactors in the pathogenesis of tau pathology. The second chapter investigates the association between pathological hallmarks and functional deficits in the aged PS19 tauopathy model. The findings indicate that a diverse spectrum of pathological tau species may underly different symptoms and that neuroinflammation might contribute to functional deficits independent of tau pathology. In the third chapter, we isolated and characterized the HMW tau species with seeding capabilities from the PS19 brains. Using unbiased quantitative mass spectrometry analysis, we identified Bassoon (BSN), a presynaptic protein, as a crucial interactor of the HMW tau seed. BSN overexpression exacerbated tau-seeding and toxicity both in vitro and in the Drosophila model of tauopathy. Conversely, the downregulation of BSN reduced tau spreading and overall disease pathology in the PS19 mice, indicating the important role of BSN in taumediated pathogenesis. In chapter four, we studied the disease-associated p.Pro3866Ala missense mutation in BSN and further evaluated the mechanisms through which BSN could induce toxicity and neurodegeneration. Using CRISPR-Cas9 technology, we developed a knock-in mouse model harboring the BSN P3866A missense mutation in the endogenous murine Bsn. We observed somatic BSN accumulation suggesting that the P3866A mutation might be enhancing the aggregation propensity of BSN and provide a conducive environment to promote tau aggregation. Furthermore, we observed dysregulation in protein degradation pathways, neuroinflammation, and enhanced synapse elimination by microglia. These findings underscore the pivotal role of BSN in providing a favorable environment for tau aggregation and influencing the properties of the tau seed, thereby contributing to neurodegenerative processes. Overall, our results indicate that targeting BSN could be a potential therapeutic intervention for neurodegenerative diseases.
Deletion of miR‐33, a regulator of the ABCA1–APOE pathway, ameliorates neuropathological phenotypes in APP/PS1 mice
(Wiley, 2024) Tate, Mason; Wijeratne, H. R. Sagara; Kim, Byungwook; Philtjens, Stéphanie; You, Yanwen; Lee, Do-Hun; Gutierrez, Daniela A.; Sharify, Daniel; Wells, Megan; Perez-Cardelo, Magdalena; Doud, Emma H.; Fernandez-Hernando, Carlos; Lasagna-Reeves, Cristian; Mosley, Amber L.; Kim, Jungsu; Biochemistry and Molecular Biology, School of Medicine
Introduction: Rare variants in ABCA1 increase the risk of developing Alzheimer's disease (AD). ABCA1 facilitates the lipidation of apolipoprotein E (apoE). This study investigated whether microRNA-33 (miR-33)-mediated regulation of this ABCA1-APOE pathway affects phenotypes of an amyloid mouse model. Methods: We generated mir-33+/+;APP/PS1 and mir-33-/-;APP/PS1 mice to determine changes in amyloid pathology using biochemical and histological analyses. We used RNA sequencing and mass spectrometry to identify the transcriptomic and proteomic changes between our genotypes. We also performed mechanistic experiments by determining the role of miR-33 in microglial migration and amyloid beta (Aβ) phagocytosis. Results: Mir-33 deletion increases ABCA1 levels and reduces Aβ accumulation and glial activation. Multi-omics studies suggested miR-33 regulates the activation and migration of microglia. We confirm that the inhibition of miR-33 significantly increases microglial migration and Aβ phagocytosis. Discussion: These results suggest that miR-33 might be a potential drug target by modulating ABCA1 level, apoE lipidation, Aβ level, and microglial function. Highlights: Loss of microRNA-33 (miR-33) increased ABCA1 protein levels and the lipidation of apolipoprotein E. Loss of miR-33 reduced amyloid beta (Aβ) levels, plaque deposition, and gliosis. mRNAs and proteins dysregulated by miR-33 loss relate to microglia and Alzheimer's disease. Inhibition of miR-33 increased microglial migration and Aβ phagocytosis in vitro.
Evaluation of Alpha-Synuclein and Tau Antiaggregation Activity of Urea and Thiourea-Based Small Molecules for Neurodegenerative Disease Therapeutics
(American Chemical Society, 2024) Ganegamage, Susantha K.; Ademoye, Taiwo A.; Patel, Henika; Alnakhala, Heba; Tripathi, Arati; Nguyen, Cuong Calvin Duc; Pham, Khai; Plascencia-Villa, Germán; Zhu, Xiongwei; Perry, George; Tian, Shiliang; Dettmer, Ulf; Lasagna-Reeves, Cristian; Fortin, Jessica S.; Anatomy, Cell Biology and Physiology, School of Medicine
Alzheimer's disease (AD) and Parkinson's disease (PD) are multifactorial, chronic diseases involving neurodegeneration. According to recent studies, it is hypothesized that the intraneuronal and postsynaptic accumulation of misfolded proteins such as α-synuclein (α-syn) and tau, responsible for Lewy bodies (LB) and tangles, respectively, disrupts neuron functions. Considering the co-occurrence of α-syn and tau inclusions in the brains of patients afflicted with subtypes of dementia and LB disorders, the discovery and development of small molecules for the inhibition of α-syn and tau aggregation can be a potentially effective strategy to delay neurodegeneration. Urea is a chaotropic agent that alters protein solubilization and hydrophobic interactions and inhibits protein aggregation and precipitation. The presence of three hetero atoms (O/S and N) in proximity can coordinate with neutral, mono, or dianionic groups to form stable complexes in the biological system. Therefore, in this study, we evaluated urea and thiourea linkers with various substitutions on either side of the carbamide or thiocarbamide functionality to compare the aggregation inhibition of α-syn and tau. A thioflavin-T (ThT) fluorescence assay was used to evaluate the level of fibril formation and monitor the anti-aggregation effect of the different compounds. We opted for transmission electron microscopy (TEM) as a direct means to confirm the anti-fibrillar effect. The oligomer formation was monitored via the photoinduced cross-linking of unmodified proteins (PICUP). The anti-inclusion and anti-seeding activities of the best compounds were evaluated using M17D intracellular inclusion and biosensor cell-based assays, respectively. Disaggregation experiments were performed with amyloid plaques extracted from AD brains. The analogues with indole, benzothiazole, or N,N-dimethylphenyl on one side with halo-substituted aromatic moieties had shown less than 15% cutoff fluorescence obtained with the ThT assay. Our lead molecules 6T and 14T reduced α-syn oligomerization dose-dependently based on the PICUP assays but failed at inhibiting tau oligomer formation. The anti-inclusion effect of our lead compounds was confirmed using the M17D neuroblastoma cell model. Compounds 6T and 14T exhibited an anti-seeding effect on tau using biosensor cells. In contrast to the control, disaggregation experiments showed fewer Aβ plaques with our lead molecules (compounds 6T and 14T). Pharmacokinetics (PK) mice studies demonstrated that these two thiourea-based small molecules have the potential to cross the blood-brain barrier in rodents. Urea and thiourea linkers could be further improved for their PK parameters and studied for the anti-inclusion, anti-seeding, and disaggregation effects using transgenic mice models of neurodegenerative diseases.
The Neuroinflammatory Response Associated to Cerebral Amyloid Angiopathy (CAA)
(2021-12) Taylor, Xavier Nathaniel; Kim, Jungsu; Landreth, Gary; Oblak, Adrian; Vidal, Ruben; Lasagna-Reeves, Cristian
Cerebral amyloid angiopathy (CAA) is characterized by the cerebrovascular deposition of amyloid. The mechanisms underlying the contribution of CAA to neurodegeneration are not fully understood. In this dissertation, there are three main chapters. The first chapter investigates existing evidence regarding the amyloid diversity in CAA and its relation to tau pathology and immune response, as well as the possible contribution of molecular and cellular mechanisms, previously associated with parenchymal amyloid in Alzheimer disease (AD) and AD-related dementias, to the pathogenesis of CAA. The second chapter demonstrates differential glial reactivity and activation associated with early-stage CAA in a mouse model of Familial Danish Dementia (FDD), a neurodegenerative disease characterized by vascular accumulation of Danish amyloid (ADan). We show that early-stage CAA is associated with dysregulation in immune response networks and lipid processing, severe astrogliosis with a neurotoxic A1-astrocytic phenotype, characterized by increased expression of Complement Component 3 (C3), and decreased levels of Triggering Receptor Expressed On Myeloid Cells 2 (Trem2) with no significant reactive microgliosis. Our results also indicate how cholesterol accumulation and Apolipoprotein E (ApoE) are associated with vascular amyloid deposits at the early stages of pathology. Furthermore, we demonstrate A1 astrocytic mediation of Trem2 and microglia homeostasis. In the final chapter, we addressed whether inflammatory stimulus of other cell types are capable of inducing a subtype of neurotoxic astrocytes. Here we show a subtype of C3+ neurotoxic astrocyte are induced by activated endothelial cells that is distinct from astrocytes classically activated by microglia. We show that endothelial activated astrocytes have upregulated expression of A1-astrocytic genes and exhibit a distinctive extracellular matrix remodeling profile. Finally, we demonstrate that endothelial activated astrocytes are Decorin-positive and are associated to vascular amyloid deposits but not parenchymal amyloid plaques in mouse models and AD/CAA patients. These findings show the existence of potentially extensive and subtle functional diversity of C3+-reactive astrocytes.
The Impact of INPP5D on Microglia Response to Tau Pathology in Alzheimer's Disease
(2025-02) Soni, Dishaben Miteshkumar; Truitt, William A.; Oblak, Adrian L.; Lasagna-Reeves, Cristian; Bissel, Stephanie J.; Chu, Shaoyou
Alzheimer’s Disease (AD), the most prevalent form of dementia, is neuropathologically defined by the extracellular buildup of amyloid-beta (Aβ) plaques, the formation of intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein, and progressive neuronal degeneration, ultimately leading to cognitive decline. Genetic studies have identified immune-related risk genes linked to AD, underscoring the regulatory role of microglia in AD pathogenesis. Among these genes, INPP5D, which is exclusively expressed by microglia in the brain, has been associated with an increased risk for AD. Elevated INPP5D expression in microglia correlates with amyloid-plaque burden in human AD brain tissue, and studies indicate that INPP5D deficiency modulates amyloid pathology, with effects differing by disease stage and model system. While INPP5D modulation has been shown to impact amyloid pathology, its influence on tau pathology remains largely unexplored. This dissertation seeks to illuminate the role of INPP5D in tau pathogenesis. Our initial studies demonstrated a positive correlation between INPP5D expression and tau-seeding activity in human AD brain samples. Likewise, we observed increased INPP5D expression associated with phospho-tau AT8 levels in PS19 mice, indicating a significant link between INPP5D and tau pathology. Building on these findings, we explored the effect of Inpp5d haplodeficiency on tau pathogenesis in PS19 mice, revealing that Inpp5d haplodeficiency recovered motor functions, mitigated tau pathology, lowered proinflammatory cytokine levels and altered microglial morphology without affecting the overall cellular composition. Transcriptomic analysis also showed the upregulation of genes involved in cell migration, immune response, angiogenesis, and wound healing. These results highlight a complex interplay between Inpp5d, tau pathology, and behavioral outcomes, supporting Inpp5d’s involvement in tau pathogenesis. To explore this further, we treated primary microglia isolated from Wildtype, Inpp5d+/-, and Inpp5d-/- mice with recombinant mutant tau-preformed fibrils and insolubletau extracted from PS19 mice brains. Our results revealed increased tau uptake in Inpp5d+/- and Inpp5d-/- microglia, suggesting that Inpp5d modulation enhances tau uptake, potentially influencing disease progression through altered microglial response. While further research is needed to clarify the mechanisms through which INPP5D influences tau pathogenesis, our findings highlight INPP5D as a promising therapeutic target for modulating tau pathology and improving microglial function in AD.
The Role of ABI3 in Obesity and Metabolic Regulation
(2024-04) Smith, Daniel Curtis; Oblak, Adrian; Kim, Jungsu; Flak, Jonathan; Lasagna-Reeves, Cristian; Evans-Molina, Carmella
Abelson Interactor Protein 3 is an adaptor protein involved in cytoskeletal remodeling. ABI3 is predominantly expressed within mononuclear phagocytotic immune cells within the brain, such as macrophages, peripherally, and microglia. Until recently, little was known about the function of the ABI3 protein, and even less was known regarding its role in disease. Following the identification of a rare mutation within ABI3 that increases the risk of developing Alzheimer’s disease, our laboratory began to investigate the impact of deleting Abi3 in mouse models. While we initially set out to investigate ABI3 in the context of neurodegeneration, we unexpectedly discovered that loss of Abi3 led to obesity in mice. This discovery and the subsequent efforts to uncover the mechanisms by which loss of Abi3 induces obesity are the subject of this dissertation. First, we demonstrate that deletion of Abi3 leads to severe obesity in aged mice. We identified significant Abi3-dependent transcriptomic changes within the hypothalamus, but not adipose tissue, of these mice. These changes occurred within pathways related to immune function, and subsequent immunostaining revealed decreased microglia number and area within the mediobasal hypothalamus of Abi3-/- mice. Next, we performed a longitudinal high-fat diet study to explore the impact of loss of Abi3 on mouse body weight and metabolic regulation during chronic nutrient excess and control conditions. Intriguingly, we found that only female Abi3-/- mice exhibited increased body weight during high-fat diet feeding. Subsequent transcriptomics from the hypothalamus of female Abi3+/+ and Abi3-/- mice from both high-fat and control diet groups revealed cytoskeletal-related changes only in the obese, high-fat diet-fed female Abi3-/- mice. Follow-up immunostaining revealed decreased microglia coverage within the mediobasal hypothalamus of the obese, high-fat diet-fed female Abi3-/- mice. While much remains to be explored regarding the precise role of ABI3 in the setting of energy balance regulation and obesity, our investigations revealed that loss of ABI3 is sufficient to induce obesity and appears to occur through altered microglia function within the hypothalamus. This dissertation represents a critical first step in the investigation of a novel regulator of obesity pathology.
Translational Responses of Motor Neurons to Neurodegeneration in ALS Identifies FGF21 as a Critical Myogenic Regulatory Factor That Slows Disease Progression
(2021-12) Stansberry, Wesley Michael; Oblak, Adrian; Landreth, Gary; Lasagna-Reeves, Cristian; Pierchala, Brian; Walker, Chandler
The neuromuscular junction (NMJ) is a chemical synapse that is the site of skeletal muscle innervation by spinal motor neurons and the maintenance of the NMJ is critical for preserving musculoskeletal homeostasis. Under normal physiological conditions, spinal motor neurons have significant regenerative potential and can regrow axons in response to peripheral nerve injury. In diseases such as amyotrophic lateral sclerosis (ALS), the NMJ is dismantled and motor neurons selectively degenerate resulting in progressive muscle wasting and eventual fatal paralysis. Interestingly, some motor neurons are more resistant to degeneration, with slow motor neurons persisting for longer and, in some cases, reinnervating fast, vacant NMJ endplates, underscoring the vital role of motor neurons in supporting skeletal muscle in disease states. In this dissertation we explore the role of motor neurons in skeletal muscle maintenance in ALS. We adapted the RiboTag methodology developed by Sanz et al. to perform ribosomal profiling of motor neurons in two mouse models of ALS. In chapter two we evaluated the translatome of spinal motor neurons in the Ubqln2P497S proteostasis model. The most significant finding from this study was the dramatic downregulation of muscle-related transcripts in motor neuron cell bodies in ALS, raising the possibility of motor neurons translating mRNAs previously thought to be muscle cell-type specific in direct support of the skeletal muscles they innervate. In chapter three, another RiboTag screen comparing a sciatic nerve crush model of acute injury and the Sod1G93A ALS model identified Fgf21, a metabolic and stress-inducible hormone, as one of the most upregulated ALS-specific transcripts. Transgenic mouse models where Fgf21 is conditionally knocked out in Sod1G93A motor neurons showed reduced motor neuron survival and NMJ innervation. Behavioral and survival trials with Sod1G93A mice showed a dramatic reduction in locomotion and lifespan when Fgf21 was conditionally knocked out of motor neurons. Taken together, these data suggest Fgf21 functions in a neuroprotective capacity in ALS pathology. Here we evaluate the functions of Fgf21 and the mechanisms by which it promotes motor neuron survival and skeletal muscle innervation and metabolism.
TYK2 regulates tau levels, phosphorylation and aggregation in a tauopathy mouse model
(Springer Nature, 2024) Kim, Jiyoen; Tadros, Bakhos; Liang, Yan Hong; Kim, Youngdoo; Lasagna-Reeves, Cristian; Sonn, Jun Young; Chung, Dah-eun Chloe; Hyman, Bradley; Holtzman, David M.; Zoghbi, Huda Yahya; Anatomy, Cell Biology and Physiology, School of Medicine
Alzheimer's disease is one of at least 26 diseases characterized by tau-positive accumulation in neurons, glia or both. However, it is still unclear what modifications cause soluble tau to transform into insoluble aggregates. We previously performed genetic screens that identified tyrosine kinase 2 (TYK2) as a candidate regulator of tau levels. Here we verified this finding and found that TYK2 phosphorylates tau at tyrosine 29 (Tyr29) leading to its stabilization and promoting its aggregation in human cells. We discovered that TYK2-mediated Tyr29 phosphorylation interferes with autophagic clearance of tau. We also show that TYK2-mediated phosphorylation of Tyr29 facilitates pathological tau accumulation in P301S tau-transgenic mice. Furthermore, knockdown of Tyk2 reduced total tau and pathogenic tau levels and rescued gliosis in a tauopathy mouse model. Collectively, these data suggest that partial inhibition of TYK2 could thus be a strategy to reduce tau levels and toxicity.
Utilization of a Human Induced Pluripotent Stem Cell Model of Microglial Fractalkine Signaling Dysfunction in Alzheimer's Disease
(2025-03) Tutrow, Kaylee D.; Meyer, Jason; Bissel, Stephanie; Kim, Jungsu; Lasagna-Reeves, Cristian
Dysfunctional microglial activity has been identified as a potential mechanism leading to accumulation of amyloid beta and pTau and subsequent neurodegeneration in Alzheimer's Disease (AD). The CX3CR1/fractalkine axis serves as a mechanism for bidirectional communication between microglia and neurons, respectively, to promote an anti-inflammatory microglial state. Previous studies have demonstrated that deficiency in CX3CR1 signaling leads microglia to develop a more pro-inflammatory phenotype, induces phagocytic deficits, and increases susceptibility of neurons to cell death. The CX3CR1-V249I polymorphism was recently identified as a potential risk allele for AD. However, the role offractalk:ine dysfunction in human cells and the mechanisms by which microglia with the CX3CR1-V249I SNP contribute to neurodegeneration remain unclear. To address this shortcoming, we utilized human induced pluripotent stem cells and CRISPR/Cas9 technology to elucidate the effects of the V249I polymorphism on human microglia-like cells (hMGLs). We demonstrate effective differentiation from paired isogenic control and CX3CR1-V249I backgrounds into hMGLs. Transcriptional profiling via RNA-seq analyses demonstrated alterations in pathways such as apoptosis, toll-like receptor signaling, and the inflammasome due to the CX3CR1-V249I SNP. Both heterozygous and homozygous microglia bearing the V249I allele demonstrated decreased phagocytosis of amyloid beta in vitro compared to controls, with this effect modulated by the presence of fractalkine in heterozygous but not homozygous V249I hMGLs. Both heterozygous and homozygous V249I microglia exhibited increased stress-induced cell death compared to controls, with homozygous hMGLs demonstrating increased cell death at earlier time points. These findings suggest that the CX3CR1-V249I polymorphism may confer a dysfunctional microglia phenotype, which may subsequently contribute to neuronal dysfunction. Further investigation of microglia in neuron co-culture models demonstrated that the CX3CR1-V249I variant conferred altered neuronal excitability. Collectively, the results of this study highlight the importance of understanding CX3CR1 function in AD pathology to identify targetable mechanisms for intervention.

Browsing by Author "Lasagna-Reeves, Cristian"

Results Per Page

Sort Options