Gene expression analysis of aging muscle chronically treated with AICAR to induce AMPK activity

Jouber Calixto

Introduction

AICAR mimics the intracellular accumulation of AMP that occurs during energy stress (e.g. during exercise).
Among other targets, AICAR activates AMP-activated protein kinase (AMPK), which is thought to mediate many of its effects through altered gene expression and other mechanisms.
AICAR delays myoblast senescence (Yoon et al. 2019), improves muscle regeneration and function in various myopathy models (Peralta et al. 2016; Ljubicic et al. 2011), and healthy young mice (Narkar et al. 2008).

Introduction

Contraction-induced AMPK activation is attenuated in aged muscle (Hardman et al. 2014; Reznick et al. 2007), which may contribute to age-related muscle dysfunction.
Hypothesis: Chronic AICAR administration will reverse many age-related changes in gene expression in old skeletal muscle. Differentially expressed genes (DEGs) can be investigated by RNA sequencing.

Sarcopenia

Affects 20-50% of adults over the age of 60 years
Muscle atrophy in old age
Reduced strength
Functional decline
Increased risk of falling

Chronic AICAR injections improve treadmill endurance in old mice

Chronic AICAR injections increase body weight in old mice

Aging alters gene expression profile

DEGs in Old Saline versus Young Saline

AICAR rescues expression profile

DEGs in Old Saline versus Young Saline AND Old AICAR

Clustering of DEGs

Gene set enrichment analysis

Genes up-regulated in OS

Gene set enrichment analysis

Genes down-regulated in OS

Enriched KEGG pathways

Genes down-regulated in OS

Enriched MeSH terms

Genes down-regulated in OS

Conclusions

Affects 20-50% of adults over the age of 60 years
Muscle atrophy in old age
Reduced strength
Functional decline
Increased risk of falling

Future directions

How are specific genes within ontologies affected?
How much of AICAR’s effect is due to AMPK activation?
Determine transcription factors that are affected – how is AICAR affecting them? Through AMPK?

Special thanks

Faculty

Dr. David Thomson
Dr. Shalene Wilcox
Dr. Jonathon Hill

Undergraduate students

Andrew Smith
Kole Brodowski
Connor Johnson

Graduate cohort

Isaac Stirland
Sebastian Valencia

Funding

NIH (Grant R01 AR-051928)
BYU Gerontology Program Grant

References

Hardman, Shalene E., Derrick E. Hall, Alyssa J. Cabrera, Chad R. Hancock, and David M. Thomson. 2014. “The Effects of Age and Muscle Contraction on AMPK Activity and Heterotrimer Composition.” Experimental Gerontology 55 (July): 120–28. https://doi.org/10.1016/j.exger.2014.04.007.

Ljubicic, V., P. Miura, M. Burt, L. Boudreault, S. Khogali, J. A. Lunde, J.-M. Renaud, and B. J. Jasmin. 2011. “Chronic AMPK Activation Evokes the Slow, Oxidative Myogenic Program and Triggers Beneficial Adaptations in Mdx Mouse Skeletal Muscle.” Human Molecular Genetics 20 (17): 3478–93. https://doi.org/10.1093/hmg/ddr265.

Narkar, Vihang A., Michael Downes, Ruth T. Yu, Emi Embler, Yong-Xu Wang, Ester Banayo, Maria M. Mihaylova, et al. 2008. “AMPK and PPARδ Agonists Are Exercise Mimetics.” Cell 134 (3): 405–15. https://doi.org/10.1016/j.cell.2008.06.051.

Peralta, Susana, Sofia Garcia, Han Yang Yin, Tania Arguello, Francisca Diaz, and Carlos T. Moraes. 2016. “Sustained AMPK Activation Improves Muscle Function in a Mitochondrial Myopathy Mouse Model by Promoting Muscle Fiber Regeneration.” Human Molecular Genetics 25 (15): 3178–91. https://doi.org/10.1093/hmg/ddw167.

Reznick, Richard M., Haihong Zong, Ji Li, Katsutaro Morino, Irene K. Moore, Hannah J. Yu, Zhen-Xiang Liu, et al. 2007. “Aging-Associated Reductions in AMP-Activated Protein Kinase Activity and Mitochondrial Biogenesis.” Cell Metabolism 5 (2): 151–56. https://doi.org/10.1016/j.cmet.2007.01.008.

Yoon, Kyeong Jin, Didi Zhang, Seok-Jin Kim, Min-Chul Lee, and Hyo Youl Moon. 2019. “Exercise-Induced AMPK Activation Is Involved in Delay of Skeletal Muscle Senescence.” Biochemical and Biophysical Research Communications 512 (3): 604–10. https://doi.org/10.1016/j.bbrc.2019.03.086.