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Microgravity induces proteomics changes involved in endoplasmic reticulum stress and mitochondrial protection

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ABSTRACT

On Earth, biological systems have evolved in response to environmental stressors, interactions dictated by physical forces that include gravity. The absence of gravity is an extreme stressor and the impact of its absence on biological systems is ill-defined. Astronauts who have spent extended time under conditions of minimal gravity (microgravity) experience an array of biological alterations, including perturbations in cardiovascular function. We hypothesized that physiological perturbations in cardiac function in microgravity may be a consequence of alterations in molecular and organellar dynamics within the cellular milieu of cardiomyocytes. We used a combination of mass spectrometry-based approaches to compare the relative abundance and turnover rates of 848 and 196 proteins, respectively, in rat neonatal cardiomyocytes exposed to simulated microgravity or normal gravity. Gene functional enrichment analysis of these data suggested that the protein content and function of the mitochondria, ribosomes, and endoplasmic reticulum were differentially modulated in microgravity. We confirmed experimentally that in microgravity protein synthesis was decreased while apoptosis, cell viability, and protein degradation were largely unaffected. These data support our conclusion that in microgravity cardiomyocytes attempt to maintain mitochondrial homeostasis at the expense of protein synthesis. The overall response to this stress may culminate in cardiac muscle atrophy.

No MeSH data available.


Related in: MedlinePlus

Overview of study work flow.(A) Schematic overview of SILAC experiments. NRCMs were placed in SILAC and split into groups designated for 12, 48, and 120 h following which cell pellets were analyzed. (B) Mass Spectrometry work flow. Cell pellets were lysed, proteins were digested and analyzed by area under the curve (AUC) following separation through LC/MS/MS.
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f1: Overview of study work flow.(A) Schematic overview of SILAC experiments. NRCMs were placed in SILAC and split into groups designated for 12, 48, and 120 h following which cell pellets were analyzed. (B) Mass Spectrometry work flow. Cell pellets were lysed, proteins were digested and analyzed by area under the curve (AUC) following separation through LC/MS/MS.

Mentions: A rotating wall bioreactor engineered by NASA was used to simulate microgravity14. This bioreactor perpetually suspends cells without inducing shear, thereby creating a net gravity vector of zero315. Primary rat neonatal cardiomyocytes were placed into simulated microgravity (μg) or normal gravity (1xg) conditions (Fig. 1A). High-resolution nanoscale liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed as outlined in Fig. 1B on cells isolated over time at 12, 48, or 120 h from μg or 1xg conditions.


Microgravity induces proteomics changes involved in endoplasmic reticulum stress and mitochondrial protection
Overview of study work flow.(A) Schematic overview of SILAC experiments. NRCMs were placed in SILAC and split into groups designated for 12, 48, and 120 h following which cell pellets were analyzed. (B) Mass Spectrometry work flow. Cell pellets were lysed, proteins were digested and analyzed by area under the curve (AUC) following separation through LC/MS/MS.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037457&req=5

f1: Overview of study work flow.(A) Schematic overview of SILAC experiments. NRCMs were placed in SILAC and split into groups designated for 12, 48, and 120 h following which cell pellets were analyzed. (B) Mass Spectrometry work flow. Cell pellets were lysed, proteins were digested and analyzed by area under the curve (AUC) following separation through LC/MS/MS.
Mentions: A rotating wall bioreactor engineered by NASA was used to simulate microgravity14. This bioreactor perpetually suspends cells without inducing shear, thereby creating a net gravity vector of zero315. Primary rat neonatal cardiomyocytes were placed into simulated microgravity (μg) or normal gravity (1xg) conditions (Fig. 1A). High-resolution nanoscale liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed as outlined in Fig. 1B on cells isolated over time at 12, 48, or 120 h from μg or 1xg conditions.

View Article: PubMed Central - PubMed

ABSTRACT

On Earth, biological systems have evolved in response to environmental stressors, interactions dictated by physical forces that include gravity. The absence of gravity is an extreme stressor and the impact of its absence on biological systems is ill-defined. Astronauts who have spent extended time under conditions of minimal gravity (microgravity) experience an array of biological alterations, including perturbations in cardiovascular function. We hypothesized that physiological perturbations in cardiac function in microgravity may be a consequence of alterations in molecular and organellar dynamics within the cellular milieu of cardiomyocytes. We used a combination of mass spectrometry-based approaches to compare the relative abundance and turnover rates of 848 and 196 proteins, respectively, in rat neonatal cardiomyocytes exposed to simulated microgravity or normal gravity. Gene functional enrichment analysis of these data suggested that the protein content and function of the mitochondria, ribosomes, and endoplasmic reticulum were differentially modulated in microgravity. We confirmed experimentally that in microgravity protein synthesis was decreased while apoptosis, cell viability, and protein degradation were largely unaffected. These data support our conclusion that in microgravity cardiomyocytes attempt to maintain mitochondrial homeostasis at the expense of protein synthesis. The overall response to this stress may culminate in cardiac muscle atrophy.

No MeSH data available.


Related in: MedlinePlus