measurement-oxygen-consumption-rates-intact-caenorhabditis

Measurement of Oxygen Consumption Rates in Intact <em>Caenorhabditis elegans</em>

Optimal mitochondrial function is critical for healthy cellular activity, particularly in cells that have high energy demands like those in the nervous ...

Albany Medical College

Mutations in the presenilin (PSEN) encoding genes (PSEN1 and PSEN2) occur in most early onset familial Alzheimer's Disease. Despite the identification of the involvement of PSEN in Alzheimer's Disease (AD) ∼20 years ago, the underlying role of PSEN in AD is not fully understood. To gain insight into the biological function of PSEN, we investigated the role of the PSEN homolog SEL-12 in Caenorhabditis elegans. Using genetic, cell biological, and pharmacological approaches, we demonstrate that mutations in sel-12 result in defects in calcium homeostasis, leading to mitochondrial dysfunction. Moreover, consistent with mammalian PSEN, we provide evidence that SEL-12 has a critical role in mediating endoplasmic reticulum (ER) calcium release. Furthermore, we found that in SEL-12-deficient animals, calcium transfer from the ER to the mitochondria leads to fragmentation of the mitochondria and mitochondrial dysfunction. Additionally, we show that the impact that SEL-12 has on mitochondrial function is independent of its role in Notch signaling, γ-secretase proteolytic activity, and amyloid plaques. Our results reveal a critical role for PSEN in mediating mitochondrial function by regulating calcium transfer from the ER to the mitochondria. 

A γ-Secretase Independent Role for Presenilin in Calcium Homeostasis Impacts Mitochondrial Function and Morphology in Caenorhabditis elegans.

Oxidative stress is implicated in the pathogenesis of various neurodegenerative diseases, including Alzheimer's disease. Oxidative stress is a result of a disruption of the equilibrium between antioxidants and oxidants, in favor of oxidants. Since mitochondria are major sites of production and reduction of reactive oxygen species (ROS), measurement of ROS levels can help us determine if mitochondrial functional integrity has been compromised. In this protocol, we describe a method to measure the level of ROS in the nematode  using chloromethyl-2,7'-dichlorodihydrofluorescein diacetate (CM-HDCFDA).

Measurement of ROS in  Using a Reduced Form of Fluorescein.

Mitochondrial function is altered in various pathologies, highlighting the crucial role mitochondria plays in maintaining cellular homeostasis. Mitochondrial structure undergoes constant fission and fusion in response to changing cellular environment. Due to this, analyzing mitochondrial structure could provide insight into the physiological state of the cell. In this protocol, we describe a method to analyze mitochondrial structure in body wall muscles in the nematode  using both transgenic and dye-based approaches.

Analysis of Mitochondrial Structure in the Body Wall Muscle of .

Mitochondrial dysfunction and subsequent metabolic deregulation is observed in neurodegenerative diseases and aging. Mutations in the presenilin (PSEN) encoding genes ( and ) cause most cases of familial Alzheimer's disease (AD); however, the underlying mechanism of pathogenesis remains unclear. Here, we show that mutations in the  gene encoding a PSEN homolog,  result in mitochondrial metabolic defects that promote neurodegeneration as a result of oxidative stress. In  mutants, elevated endoplasmic reticulum (ER)-mitochondrial Ca signaling leads to an increase in mitochondrial Ca content which stimulates mitochondrial respiration resulting in an increase in mitochondrial superoxide production. By reducing ER Ca release, mitochondrial Ca uptake or mitochondrial superoxides in  mutants, we demonstrate rescue of the mitochondrial metabolic defects and prevent neurodegeneration. These data suggest that mutations in PSEN alter mitochondrial metabolic function via ER to mitochondrial Ca signaling and provide insight for alternative targets for treating neurodegenerative diseases.

Presenilin mutations deregulate mitochondrial Ca homeostasis and metabolic activity causing neurodegeneration in .

Neurodegenerative diseases like Alzheimer's disease (AD) are poised to become a global health crisis, and therefore understanding the mechanisms underlying the pathogenesis is critical for the development of therapeutic strategies. Mutations in genes encoding presenilin (PSEN) occur in most familial Alzheimer's disease but the role of PSEN in AD is not fully understood. In this review, the potential modes of pathogenesis of AD are discussed, focusing on calcium homeostasis and mitochondrial function. Moreover, research using  to explore the effects of calcium dysregulation due to presenilin mutations on mitochondrial function, oxidative stress and neurodegeneration is explored.

Article	Year
A γ-Secretase Independent Role for Presenilin in Calcium Homeostasis Impacts Mitochondrial Function and Morphology in Caenorhabditis elegans. Genetics\| PubMed ID: 26500256	2015
Measurement of ROS in Using a Reduced Form of Fluorescein. Bio-protocol\| PubMed ID: 29707606	2018
Analysis of Mitochondrial Structure in the Body Wall Muscle of . Bio-protocol\| PubMed ID: 29707607	2018
Presenilin mutations deregulate mitochondrial Ca homeostasis and metabolic activity causing neurodegeneration in . eLife\| PubMed ID: 29989545	2018
Role of Presenilin in Mitochondrial Oxidative Stress and Neurodegeneration in . Antioxidants (Basel, Switzerland)\| PubMed ID: 30149498	2018

Shaarika Sarasija

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