How Stimulus-responsive Extracellular Vesicle Release is Regulated and Associated to Lewy body disease

Doktorarbeit / Dissertation , 2021 , 199 Seiten , Note: N/A

Biologie - Neurobiologie

Lewy body (LB) disorders, such as dementia with LBs and Parkinson’s disease with dementia (PDD) are characterized by their pathological hallmark, i.e., the gradual appearance of LBs. Therefore, a deep understanding of the molecular and cellular mechanism, favoring the formation of LBs is required.These proteinaceous inclusions are found in different cell types of the nervous system. The key constituent protein-component of such inclusions is the protein alpha-synuclein (α-Syn). α-Syn along with other bio-active material gets secreted as content of extracellular vesicles (EVs). These vesicles not only excrete bioactive material but are also able to transport it to distant sites, and therefore have implications for disease pathology seeding and spreading.Using patch-clamp electrophysiology techniques along with simultaneous real-time molecular imaging, we determined the kinetics of EV-release in hippocampal neurons. We designed a pH-sensitive molecular tag, targeted specifically to membranes of EVs and applied this method to study stimulus-responsive MVB-PM fusion, in order to determine the kinetics, specific stimuli and regulators of such events. In addition, we analyzed the EV-content by performing mass spectrometry (MS) analysis and identifyed LBP-related molecular interactions.

Inhaltsverzeichnis (Table of Contents)

• Abstract
• Foreword
• List of abbreviations
• 1. Introduction
  • 1.1. Lewy bodies and Parkinson's disease
  • 1.2. Lewy bodies
  • 1.3. Lewy body pathology and hippocampus
  • 1.4. Lewy body pathology propagation and extra cellular vesicles
  • 1.5. Extracellular vesicle
  • 1.6. Neurotrophic factors and Lewy body pathology
  • 1.7. Functional periphery of basic fibroblast growth factor
  • 1.8. Aim and scope of the thesis
• 2. Methodology, methods, and materials
  • 2.1. Experimental design
    • 2.1.1. Patch clamp electrophysiology
    • 2.1.2. Cell cultures
    • 2.1.3. Exosome labelling
    • 2.1.4. Working model of pHluorin tag
    • 2.1.5. A suitable bioelectric stimulus
      • 2.1.5.1. 100 Hz
    • 2.1.6. Nano particle tracking analysis
    • 2.1.7. Weighted protein co-expression network analysis
  • 2.2. Material and methods
    • 2.2.1. Chemicals used for electrophysiology
    • 2.2.2. Miscellaneous
    • 2.2.3. LUHMES cell culture
    • 2.2.4. Calcium imaging fura-2 loading experiments
    • 2.2.5. Immunocytochemistry for imaging
    • 2.2.6. Other materials and resources
• 3. Results
  • 3.1. Abundant a-Syn expression and exosomal release
    • 3.1.1. α-Syn overexpression results an elongated morphology in LUHMES cells
    • 3.1.2. a-Syn overexpression resulted in enhanced secretion of extracellular vesicles in LUHMES cells
    • 3.1.3. Exosome release in LUHMES cells is calcium dependent
    • 3.1.4. α-Syn overexpression enhances extracellular vesicles in primary hippocampal neurons
  • 3.2. Calcium level and exosomal release
    • 3.2.1. A relative slower rate of MVB-PM fusion
    • 3.2.2. HFS enhanced MVB-PM fusion events with subsided success rate
  • 3.3. Growth factors and exosomal release
    • 3.3.1. The effects of growth factors are restricted largely to intraneuronal physiological environment
    • 3.3.2. bFGF regulates exosomal release
    • 3.3.3. SNARE proteins mediate bFGF regulated exosomal release

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This thesis investigates the regulation of stimulus-responsive extracellular vesicle release and its connection to Lewy body disease. It focuses on the role of calcium influx, multivesicular body (MVB) biogenesis, and the impact of basic fibroblast growth factor (bFGF) on exosome release. The work aims to elucidate the underlying mechanisms of exosome secretion and their potential involvement in the propagation of Lewy body pathology.

• Regulation of Extracellular Vesicle Release
• Role of Calcium Influx in Exosome Secretion
• Multivesicular Body Biogenesis and Exosome Formation
• Impact of Basic Fibroblast Growth Factor (bFGF) on Exosome Release
• Connection of Exosome Release to Lewy Body Disease

Zusammenfassung der Kapitel (Chapter Summaries)

The introduction provides an overview of Lewy bodies, their association with Parkinson's disease, and the role of extracellular vesicles in their propagation. It also discusses the impact of neurotrophic factors, particularly bFGF, on Lewy body pathology.

Chapter 2 details the methodology, methods, and materials used in the research. This includes descriptions of patch clamp electrophysiology, cell culture techniques, exosome labeling, and the use of bioelectric stimuli.

Chapter 3 presents the research findings. It explores the connection between α-syn expression, exosomal release, and calcium levels. The chapter also investigates the role of growth factors, particularly bFGF, in regulating exosomal release.

Schlüsselwörter (Keywords)

The main keywords of this thesis include extracellular vesicles, exosomes, Lewy body disease, Parkinson's disease, α-synuclein, calcium influx, MVB biogenesis, bFGF, SNARE proteins, neurotrophic factors, and cellular signaling pathways. This work examines the interplay between these factors and their influence on exosome secretion and its potential implications for Lewy body pathology.

• Hochschule: Technische Universität München (German Center for Neurodegenerative Diseases (DZNE))
• Note: N/A
• Autor: Rohit Kumar (Autor:in)
• Erscheinungsjahr: 2021
• Seiten: 199
• Katalognummer: V1351407
• ISBN (PDF): 9783346860774
• ISBN (Buch): 9783346860781
• Sprache: Englisch
• Schlagworte: stimulus-responsive, extracellular, vesicle, release, regulated, associated, lewy