Scope Three fluorescence biosensors were developed based on a 3T3-L1 preadipocyte line that stably expressed Nfkb-RE/GFP, Fabp4-P/CFP, and Nrf2-P/YFP fluorescent reporters. We hypothesized that nutraceuticals’ inflammatory, adipogenic, and antioxidant status will be identified based on the change in fluorescence in reporter adipocytes. We validated these assays with activators of NFκB, FABP4-regulating PPARγ, NFR2 and, thereafter, tested known and unknown properties of mangosteens (MG), the xanthone metabolites in mangosteen fruit. Methods and results We validated inflammatory and adipogenic properties of α-MG using a Nfkb-RE/GFP biosensor assay. Next, we identified unique properties of γ-MG, a minor mangosteen xanthone. γ-MG suppressed adipogenesis and adiponectin, but inhibited the Nfkb-RE/GFP reporter and secretion of inflammatory MCP-1 as compared to the control adipocytes. We found that the inhibition of adipogenesis and Nfkb-mediated inflammation depends on a dose-dependent reduction of Nrf2 promoter activity by α-MG. The Nrf2 inhibition resulted in the reduced Pparg expression. α-MG did not directly influence Pparg activity in Fabp4-P/CFP adipocytes. Conclusion α-MG-mediated antioxidant response via Nrf2 is a mechanism preventing adipogenesis and inflammation in adipocytes. Combined application of high-throughput biosensors could provide an effective platform for the identification of nutraceuticals and the mechanism of their actions in adipocytes and, potentially, in obese patients.

The deregulation of B cell differentiation has been shown to contribute to autoimmune disorders, hematological cancers, and aging. We provide evidence that the retinoic acid-producing enzyme aldehyde dehydrogenase 1a1 (Aldh1a1) is an oncogene suppressor in specific splenic IgG1+/CD19− and IgG1+/CD19+ B cells populations. Aldh1a1 regulated transcription factors during B cell differentiation in a sequential manner: 1) retinoic acid receptor alpha (Rara) in IgG1+/CD19− and 2) zinc finger protein Zfp423 and peroxisome proliferator-activated receptor gamma (Pparg) in IgG1+/CD19+ splenocytes. In Aldh1a1−/− mice, splenic IgG1+/CD19− and IgG1+/CD19+ B cells acquired expression of proto-oncogenic genes c-Fos, c-Jun, and Hoxa10 that resulted in splenomegaly. Human multiple myeloma B cell lines also lack Aldh1a1 expression; however, ectopic Aldh1a1 expression rescued Rara and Znf423 expression in these cells. Our data highlight a mechanism by which an enzyme involved in vitamin A metabolism can improve B cell resistance to oncogenesis.

Unraveling mechanisms regulating gammopathies, abnormal immunoglobulin production is necessary to improve treatments of a number of blood cancers, such as multiple myeloma. Retinoic acid and retinaldehyde, a transcriptionally active metabolites of vitamin A, play a key role in differentiation processes. RA is produced by the aldehyde dehydrogenase‐1 family of enzymes (Aldh1a1, a2, a3). Our objective was to identify key genes regulating the cellular levels of these metabolites.Our studies in healthy subjects’ showed that Aldh1a1 is the predominantly expressed Aldh1 enzyme in circulating B cells comprising majority of PBMC fraction. In contrast, two myeloma B cell lines, U266 and RPMI8226 lack Aldh1a1 expression. PBMC from multiple myeloma patients showed an expression profile similar to that of U266. We showed that similar to human B cells, naïve (CD19−) and committed (CD19+) splenic B cells from WT mice predominantly expressed Aldh1a1, whereas in Aldh1a1−/− mice these B cells were complete depleted of Aldh1 expression. In both genotypes B cell differentiation from CD19− to CD19+ phenotype was associated with the loss of Aldh1a1 and a2. The change in the RA production in CD19− and CD19+ cells was accompanied by changed levels of key proteins such as RARa, HoxA10, and PPARg. Our studies suggest that Aldh1 enzymes are important for regulation of Ig production and their deficiency is associated with malignant B cells.Grant Funding Source: Nutrition (ASN)