Biology subjects

Rustan, A. C.

Publications and source records attributed to Rustan, A. C..

3 recordsLinked to original sources

bioRxiv2026

Intrinsic IL-6 expression reduces rhIL-6-induced JAK/STAT activation and promotes glucose and oleic acid oxidation in cultured human myoblasts

Interleukin-6 (IL-6), produced by skeletal muscle and extramuscular tissues, regulates skeletal muscle function through the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. However, the interaction between intrinsic (locally produced) IL-6 and extrinsic (circulating) IL-6 in skeletal muscle remains unclear. We investigated whether and how intrinsic expression of IL-6 in cultured primary human myoblasts influences their response to extrinsic stimulation with recombinant human IL-6 (rhIL-6). Using gene silencing, we found that suppression of intrinsic IL-6 enhanced rhIL-6-induced phosphorylation of STAT1 and STAT3. Silencing STAT3 also increased rhIL-6-induced STAT1 phosphorylation, but silencing STAT1 had no effect on STAT3 phosphorylation. Pretreatment of myoblasts with neutralising anti-IL-6 antibodies increased phosphorylation of STAT1 and STAT3 induced by 50 ng/mL rhIL-6, whereas pretreatment with 5 ng/mL rhIL-6 reduced this response. Despite increased JAK/STAT signalling, IL-6 silencing decreased glucose and oleic acid uptake and oxidation under both basal and rhIL-6-stimulated conditions. Collectively, our results imply that intrinsic IL-6 restrains activation of the JAK/STAT pathway by extrinsic IL-6, but acts synergistically with it to promote myoblast energy metabolism.

cell biology↗

bioRxiv2025

PDK1: one abbreviation, two kinases, relentless confusion

Despite peer review, hundreds of biomedical articles contain errors due to identical abbreviations that refer to different proteins. This includes PDK1, denoting both pyruvate dehydrogenase kinase 1 and 3-phosphoinositide-dependent protein kinase 1. Our analysis shows that one-out-of-five articles with the term PDK1 on PubMed, published in 2019-2026, state incorrect antibodies, refer to incorrect sequences for PCR, gene silencing, or plasmids, merge the properties of the two proteins, or incorrectly cite the other protein. Confusion extends to websites of biotechnology providers, where PDK1 antibodies and recombinant proteins were misattributed. To mitigate PDK1 abbreviation misuse, we recommend using unique protein abbreviations, clear antibody and sequence identification, and implementation of more rigorous peer review processes, supported by our newly developed PDK1-TermTracker citation network visualization and analysis service.

biochemistry↗

bioRxiv2025

MyoFuse: A fully AI-based workflow for automated quantification of skeletal muscle cell fusion in vitro

BackgroundThe myogenic fusion index (FI) is commonly used in skeletal muscle cell culture to assess the ability of myoblasts to form myotubes, as the ratio of myoblast nuclei fused with myotubes over the total number of myoblasts. The manual quantification of the FI from 2D microscopy images is tedious and biased, thus several automated methods have been developed. However, they still face challenges such as efficient nucleus segmentation and classification of fused and isolated myoblast nuclei. Here, we developed a novel workflow entirely based on AI for fully automated and unbiased quantification of the FI. ResultsUsing current methods, we show that myoblast nuclei located above or below myotubes can significantly corrupt accurate FI computation. To circumvent this issue, we developed MyoFuse which enables an accurate and high-throughput segmentation and classification of myonuclei. It comprises a nuclei segmentation step using Cellpose, followed by a classification network trained with Svetlana. MyoFuse demonstrated strong accuracy when tested against manual annotation in mouse C2C12 and human primary myotubes. The trained classifier is able to differentiate myotube nuclei from myoblast nuclei based on myotube cytoplasm staining only. Experimental comparisons also highlighted that the previously developed methods lead to a significant overestimation of the FI. ConclusionIn summary, we underscore the lack of accuracy of traditional methods for automated FI quantification. MyoFuse enables a direct and accurate segmentation of nuclei even in nuclei clusters frequently observed in myotubes. This workflow thus offers a new and more reliable method to evaluate the FI. It also limits the selection bias by processing large images.

cell biology↗