Abstract
Bone marrow adipocyte formation plays a role in bone homeostasis and whole body energy metabolism. However, the transcriptional landscape and signaling pathways associated with adipocyte lineage commitment and maturation are not fully delineated. Thus, we performed global gene expression profiling during adipocyte differentiation of human bone marrow stromal (mesenchymal) stem cells (hMSCs) and identified 2,589 up-regulated and 2,583 down-regulated mRNA transcripts. Pathway analysis on the up-regulated gene list untraveled enrichment in multiple signaling pathways including insulin receptor signaling, focal Adhesion, metapathway biotransformation, a number of metabolic pathways e.g. selenium metabolism, Benzo(a)pyrene metabolism, fatty acid, triacylglycerol, ketone body metabolism, tryptophan metabolism, and catalytic cycle of mammalian flavin-containing monooxygenase (FMOs). On the other hand, pathway analysis on the down-regulated genes revealed significant enrichment in pathways related to cell cycle regulation. Based on these data, we assessed the effect of pharmacological inhibition of FAK signaling using PF-573228, PF-562271, and InsR/IGF-1R using NVP-AEW541 and GSK-1904529A on adipocyte differentiation. hMSCs exposed to FAK or IGF-1R/InsR inhibitors exhibited fewer adipocyte formation (27–58% inhibition, P<0005). Concordantly, the expression of adipocyte-specific genes AP2, AdipoQ, and CEBPα was significantly reduced. On the other hand, we did not detect significant effects on cell viability as a result of FAK or IGF-1R/InsR inhibition. Our data identified FAK and insulin signaling as important intracellular signaling pathways relevant to bone marrow adipogenesis.
Highlights
There is an increasing interest in studying the biology of bone marrow adipocytes (BMA) due to a shift in our understanding of their role as a passive filler of bone marrow space left behind during conditions of hematopoiesis impairment or bone loss [1] to an active tissue participating in bone and bone marrow homeostasis and whole body energy metabolism [2]
We report that Focal adhesion kinase (FAK) and insulin receptor signaling pathways regulate bone marrow adipogenesis
Adipocytic differentiation human mesenchymal stem cell (hMSC) were seeded into four-well plates and exposed to adipogenic induction media composed of Dulbecco’s modified Eagle medium (DMEM), 10% fetal bovine serum (FBS), 10% horse serum (Gibco, U.S.A.), 100 μM dexamethasone (Sigma, U.K.), 1 μM Rosiglitazone (BRL) (Novo Nordisk Bagsvaerd, Denmark), 3 μg/ml insulin (Sigma, U.K.), 450 μM isobutylmethylxanthine (IBMX) (Sigma, U.K.), and 1% penicillin-streptomycin (Sigma, U.K.) supplemented with FAK inhibitors (PF-573228 and PF-562271) or insulin-like growth factor 1 receptor (IGF-1R)/insulin receptor (InsR) inhibitors (NVP-AEW541 and GSK1904529A), which were purchased from Selleckchem Inc. (Selleckchem Inc., Houston, TX, U.S.A.)
Summary
There is an increasing interest in studying the biology of bone marrow adipocytes (BMA) due to a shift in our understanding of their role as a passive filler of bone marrow space left behind during conditions of hematopoiesis impairment or bone loss [1] to an active tissue participating in bone and bone marrow homeostasis and whole body energy metabolism [2]. Multipotent MSCs become committed to adipocytic lineage, while in the maturation c 2018 The Author(s).
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