Uncovering mechanisms of thiazolidinediones on osteogenesis and adipogenesis using spatial fluxomics

Highlights•MSDC-0602K differentially affects BM-MSCs and AT-MSCs.•Bioorthogonal click chemistry allowed measurement of pyruvate pools.•Subcellular metabolic flux analysis revealed rewiring of pyruvate pathways.•Metabolic flux analysis of TG synthesis showed distinct adipogenic strategies.AbstractObjectiveInsulin-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-0602 K, on human mesenchymal stem cells (MSCs).MethodsWe 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-0602 K differentially affected bone marrow-derived MSCs (BM-MSCs) and adipose tissue-derived MSCs (AT-MSCs). In BM-MSCs, MSDC-0602 K promoted osteoblastic differentiation and suppressed adipogenesis. This effect was clearly distinct from that of the earlier drugs and that on AT-MSCs.ResultsFluxomic 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-0602 K retains the capacity to inhibit MPC, akin to rosiglitazone but unlike pioglitazone, enabling the utilization of alternative metabolic pathways. Notably, MSDC-0602 K exhibits a limited lipogenic potential compared to both rosiglitazone and pioglitazone, each of which employs a distinct lipogenic strategy.ConclusionsThese 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.Graphical abstract