Sakari Mäntyselkä

Our new preprint suggest that in vitro mechanical cyclic stretching alone induces many similar molecular responses as exercise in vivo.

I thank all the co-authors and especially my PhD supervisors @juhahulmi.bsky.social @riikka-k.bsky.social and Elina Kalenius.

We also manipulated PHGDH in different ways in human myoblasts and myotubes. Although we found rather mixed results on the importance of PHGDH for protein synthesis, our other findings, together with the existing literature, suggest that PHGDH is important in myogenesis. 3/3

Glycolytic metabolism and biomass production from glucose in human skeletal muscle growth | American Journal of Physiology-Cell Physiology | American Physiological Society Skeletal muscle is the main consumer of glucose after a mixed meal, and resistance exercise further increases muscle glucose uptake. Emerging evidence suggests that glucose uptake in muscles is not only stored as glycogen or used as a fuel but can also be incorporated into other biomass during growth. We aimed to study the utilization of glucose-derived carbons for protein, RNA, and lipid synthesis during human skeletal muscle (HSkM) cell growth. We also investigated whether muscle growth in vivo by resistance training (RT) affects the abundance of metabolites and enzymes required for these processes in human muscle. We found that differentiated HSkM cells incorporated glucose-derived carbon into proteins, RNA, and lipids, and anabolic stimulation further increased these processes. Liquid chromatography-mass spectrometry metabolomics and proteomics revealed that 10 weeks of RT in humans increased essential metabolites and enzymes for nucleotide, serine, and glycine synthesis, including phosphoglycerate dehydrogenase (PHGDH) in muscle. We also examined whether the PHGDH enzyme, starting the serine synthesis pathway branching from glycolysis, is sufficient and essential for human muscle protein, RNA, and lipid anabolism. We found that PHGDH inhibitors decreased protein synthesis and glucose-derived carbon incorporation into macromolecules, whereas manipulation of PHGDH abundance had mixed effects. Moreover, PHGDH was revealed to be important for myogenesis. The data suggest that glucose is not only used for ATP generation but also as a building block in human muscle cell growth. The results open new avenues for studies investigating the mechanisms of RT and muscle growth in improving muscle glucose metabolism.

We found that human muscle cells (myotubes) utilized glucose-derived carbon for the synthesis of RNA, protein, and lipids. Moreover, certain essential metabolites and enzymes (e.g., PHGDH) required for this process were elevated in response to resistance training. 2/3

I am pleased to share our new research article (in press version) entitled Glycolytic metabolism and biomass production from glucose in human skeletal muscle growth. Link in the comments. 1/3 #myoblue #SkeletalMuscle

Individual responses to exercise training as the main theme of an international conference in Jyväskylä, November 19–21, 2025 Why do some people progress faster in exercise training than others? How can training responses be predicted, and how does genetics influence the outcomes of training? These questions are addressed at the international coaching science conference.

Why do some progress faster in resistance training? 💪
How do genetics and physiology shape training responses? 🏋️‍♀️
Join us in Jyväskylä, Finland, Nov 19–21 for the Inter-Individual Variation in Resistance Training Responses Conference.
www.jyu.fi/en/news/indi...

Eli Lilly in $650M pact to boost muscle
#myoblue
www.nature.com/articles/s41...

I assume that today will be a great talk!

One major, unsolved problem is all those unknown signals in MS metabolomics data. To predict what they are, Mike Skinneder has developed DeeMet. He will give the 17th HyperMet talk next Thursday at 15 h Munich time. Join here (please RT): tum-conf.zoom-x.de/j/6392132327...

Really looking forward to Lykke Sylow given the 16th HyperMet talk this Thursday 15 h. Whe will talk about the effect of hypertrophy stimulation on fat mass and glucose homeostasis (recent preprint). Please RT and join here: tum-conf.zoom-x.de/j/6903199711...

Our pre-print is now available 🤓

Conference: Inter-individual variation in exercise. Please join! The speakers are e.g.
@mackinprof.bsky.social, @abigailmackey1.bsky.social, M Bamman, T Hornberger, M Roberts, B Schoenfeld, M Perola, G Nader, E Sillanpää, A Hecksteden, W Derave, P Atherton, J Ahtiainen and me.
tinyurl.com/34xzsdss

#myoblue

A comparison of human skeletal muscle cell maturation in 2D versus 3D culture: A quantitative proteomic study. #myoblue

physoc.onlinelibrary.wiley.com/doi/10.14814...

The commonly used antibiotic streptomycin reduces protein synthesis and differentiation in cultured C2C12 myotubes The antibiotic streptomycin is an integral part of cell culture medium. Because streptomycin inhibits bacterial protein synthesis, streptomycin might also have off-target effects on muscle cell funct...

The commonly used antibiotic streptomycin reduces protein synthesis and differentiation in cultured C2C12 myotubes
physoc.onlinelibrary.wiley.com/doi/10.14814...

Very interesting study! Congratulations!

This review highlights the molecular mechanisms that regulate glucose utilization in skeletal muscle, the primary site of glucose storage and oxidation.

Erik A. Richter, et al.
doi.org/10.1152/phys...
#GlucoseMetabolism #InsulinSensitization

Serine synthesis pathway enzyme PHGDH is critical for muscle cell biomass, anabolic metabolism, and mTORC1 signaling | American Journal of Physiology-Endocrinology and Metabolism | American Physiologi... Cells use glycolytic intermediates for anabolism, e.g., via the serine synthesis and pentose phosphate pathways. However, we still understand poorly how these metabolic pathways contribute to skeletal...

Very interesting study! We have studied the role of serine synthesis in muscle cell growth using cultured muscle cells and NCT-503 and CBR-5884. journals.physiology.org/doi/full/10....

De novo serine biosynthesis is protective in mitochondrial disease Jackson et al. show that serine becomes an essential amino acid in mitochondrial muscle disease, delaying disease progression. Blocking local biosynthesis of serine challenges cellular phospholipid ho...

Muscle needs to make serine from glucose to protect the fibers from mitochondrial disease. Read our story, a tour de force of Anastasiia Marmyleva and Christopher Jackson @SWAN @STEMM Helsinki University www.cell.com/cell-reports...

#myoblue

I look forward to the results of the human clinical trial in the future! Very interesting research area! clinicaltrials.gov/study/NCT056...

Insights into human muscle biology from human primary skeletal muscle cell culture - Journal of Muscle Research and Cell Motility This review arises from the symposium held in honour of Prof Jenny Morgan at UCL in 2024 and the authors would like to acknowledge the outstanding contribution that Prof Morgan has made to the field o...

Considerations of working with human primary muscle cells - happy to have contributed to this important topic. Thank you Tom Francis and Steve Harridge for inviting me and Casper Soendenbroe to join you!

link.springer.com/article/10.1...

I can fully recommend Juha Hulmi! I am a final year PhD student in Juha's group.

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Excited to share this! We found that muscles "remember" at the proteome level that they have been training. We also report quite reproducible proteome response to resistance training.

physoc.onlinelibrary.wiley.com/doi/full/10....

@jphysiol.bsky.social @varjosal.bsky.social

Scientists, academics, researchers: We’re excited to share that @altmetric.com is now tracking mentions of your research on Bluesky! 🧪

Human skeletal muscle possesses both reversible proteomic signatures and a retained proteomic memory after repeated resistance training Investigating repeated resistance training separated by a training break enables exploration of the potential for a proteomic memory of skeletal muscle growth. Our aim was to examine skeletal muscle p...

Great study by my PhD supervisor Juha Hulmi and my colleague PhD student Eeli Halonen and their team and collaborators like @varjosal.bsky.social et al!
"Human skeletal muscle possesses both reversible proteomic signatures and a retained proteomic memory..." #myoblue
www.biorxiv.org/content/10.1...

Very interesting and great study by Horberger Lab and their collaborators! "Identification of a Resistance Exercise-Specific Signaling Pathway that Drives Skeletal Muscle Growth" www.researchsquare.com/article/rs-4... #myoblue