OBJECTIVE: Insulin-sensitizing drugs, despite their broad use against type 2 diabetes, can adversely affect bone health, and the mechanisms underlying these side effects remain largely unclear. Here, we investigated the different metabolic effects of a series of thiazolidinediones, including rosiglitazone, pioglitazone, and the second-generation compound MSDC-0602K, on human mesenchymal stem cells (MSCs). METHODS: We developed 13C subcellular metabolomic tracer analysis measuring separate mitochondrial and cytosolic metabolite pools, lipidomic network-based isotopologue models, and bioorthogonal click chemistry, to demonstrate that MSDC-0602K differentially affected bone marrow-derived MSCs (BM-MSCs) and adipose tissue-derived MSCs (AT-MSCs). In BM-MSCs, MSDC-0602K promoted osteoblastic differentiation and suppressed adipogenesis. This effect was clearly distinct from that of the earlier drugs and that on AT-MSCs. RESULTS: Fluxomic data reveal unexpected differences between this drug's effect on MSCs and provide mechanistic insight into the pharmacologic inhibition of mitochondrial pyruvate carrier 1 (MPC). Our study demonstrates that MSDC-0602K retains the capacity to inhibit MPC, akin to rosiglitazone but unlike pioglitazone, enabling the utilization of alternative metabolic pathways. Notably, MSDC-0602K exhibits a limited lipogenic potential compared to both rosiglitazone and pioglitazone, each of which employs a distinct lipogenic strategy. CONCLUSIONS: These findings indicate that the new-generation drugs do not compromise bone structure, offering a safer alternative for treating insulin resistance. Moreover, these results highlight the ability of cell compartment-specific metabolite labeling by click reactions and tracer metabolomics analysis of complex lipids to discover molecular mechanisms within the intersection of carbohydrate and lipid metabolism.

Chemistry of Bioconjugates Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo nám 2 166 10 Prague Czechia

Laboratory of Metabolism of Bioactive Lipids Institute of Physiology of the Czech Academy of Sciences Videnska 1083 14200 Prague Czechia

Laboratory of Molecular Physiology of Bone Institute of Physiology of the Czech Academy of Sciences Videnska 1083 14200 Prague Czechia

Laboratory of Molecular Physiology of Bone Institute of Physiology of the Czech Academy of Sciences Videnska 1083 14200 Prague Czechia; Faculty of Science Charles University Albertov 6 128 00 Prague Czech Republic

Laboratory of Translational Metabolism Institute of Physiology of the Czech Academy of Sciences Videnska 1083 14200 Prague Czechia

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