miR-223-3p as a Potential Biomarker and Player for Adipose Tissue Dysfunction Preceding Type 2 Diabetes Onset

Circulating microRNAs (miRNAs) have been proposed as biomarkers for type 2 diabetes (T2D). Adipose tissue (AT), for which dysfunction is widely associated with T2D development, has been reported as a major source of circulating miRNAs. However, the role of dysfunctional AT in the altered pattern of circulating miRNAs associated with T2D onset remains unexplored. Herein, we investigated the relationship between T2D-associated circulating miRNAs and AT function, as well as the role of preadipocytes and adipocytes as secreting cells of candidate circulating miRNAs. Among the plasma miRNAs related to T2D onset in the CORonary Diet Intervention with Olive oil and cardiovascular PREVention (CORDIOPREV) cohort, baseline miR-223-3p levels (diminished in patients who next developed T2D [incident-T2D]) were significantly related to AT insulin resistance (IR). Baseline serum from incident-T2D participants induced inflammation and IR in 3T3-L1 adipocytes. We demonstrated that tumor necrosis factor (TNF)-alpha inhibited miR-223-3p secretion while enhancing miR-223-3p intracellular accumulation in 3T3-L1 (pre)adipocytes. Overexpression studies showed that an intracellular increase of miR-223-3p impaired glucose and lipid metabolism in these cells. Our findings provide mechanistic insights into the alteration of circulating miRNAs preceding T2D, unveiling both preadipocytes and adipocytes as miR-223-3p-secreting cells and suggesting that inflammation promotes miR-223-3p intracellular accumulation, which might contribute to (pre)adipocyte dysfunction and body metabolic dysregulation

miR-223-3p as a potential biomarker and player for adipose tissue dysfunction preceding type 2 diabetes onset

Circulating microRNAs (miRNAs) have been proposed as biomarkers for type 2 diabetes (T2D). Adipose tissue (AT), for which dysfunction is widely associated with T2D development, has been reported as a major source of circulating miRNAs. However, the role of dysfunctional AT in the altered pattern of circulating miRNAs associated with T2D onset remains unexplored. Herein, we investigated the relationship between T2D-associated circulating miRNAs and AT function, as well as the role of preadipocytes and adipocytes as secreting cells of candidate circulating miRNAs. Among the plasma miRNAs related to T2D onset in the CORonary Diet Intervention with Olive oil and cardiovascular PREVention (CORDIOPREV) cohort, baseline miR-223-3p levels (diminished in patients who next developed T2D [incident-T2D]) were significantly related to AT insulin resistance (IR). Baseline serum from incident-T2D participants induced inflammation and IR in 3T3-L1 adipocytes. We demonstrated that tumor necrosis factor (TNF)-alpha inhibited miR-223-3p secretion while enhancing miR-223-3p intracellular accumulation in 3T3-L1 (pre)adipocytes. Overexpression studies showed that an intracellular increase of miR-223-3p impaired glucose and lipid metabolism in these cells. Our findings provide mechanistic insights into the alteration of circulating miRNAs preceding T2D, unveiling both preadipocytes and adipocytes as miR-223-3p-secreting cells and suggesting that inflammation promotes miR-223-3p intracellular accumulation, which might contribute to (pre)adipocyte dysfunction and body metabolic dysregulation

Hepatic p63 regulates steatosis via IKK beta/ER stress

p53 family members control several metabolic and cellular functions. The p53 ortholog p63 modulates cellular adaptations to stress and has a major role in cell maintenance and proliferation. Here we show that p63 regulates hepatic lipid metabolism. Mice with liver-specific p53 deletion develop steatosis and show increased levels of p63. Down-regulation of p63 attenuates liver steatosis in p53 knockout mice and in diet-induced obese mice, whereas the activation of p63 induces lipid accumulation. Hepatic overexpression of N-terminal transactivation domain TAp63 induces liver steatosis through IKK beta activation and the induction of ER stress, the inhibition of which rescues the liver functions. Expression of TAp63, IKK beta and XBP1s is also increased in livers of obese patients with NAFLD. In cultured human hepatocytes, TAp63 inhibition protects against oleic acid-induced lipid accumulation, whereas TAp63 overexpression promotes lipid storage, an effect reversible by IKK beta silencing. Our findings indicate an unexpected role of the p63/IKK beta/ER stress pathway in lipid metabolism and liver disease.We deeply thank Dr Manuel Serrano (Spanish National Cancer Research Center, CNIO, Spain) for kindly providing p53 null mice and critically reading the article. This work has been supported by grants from Ministerio de Economia y Competitividad (C.D.: BFU2014-55,871; R.N.: BFU2015-70,664-R; M.M.M.: BFU2013-44229-R; A.C.: SAF2016-79381-R, FEDER/UE; GS: SAF2013-43506-R; M.L.M.-C.: SAF2014-54658-R; M.L.: SAF2015-71026-R; P.A.: SAF2015-64352-R; B.G.-T.: FPI Severo Ochoa CNIC program SVP-2013-067639), Xunta de Galicia (M.L.: 2015-CP079; R.N.: 2015-CP080 and PIE13/00024), Comunidad de Madrid (G.S.: S2010/BMD-2326); Fondo de Investigaciones Sanitarias (M.M.: PI10/01692), Fundacion SEEN (R.N.), GV-Departamento de Salud-2013111114 (to M.L.M.-C.), ISCIII: PIE14/00031 (to M.L.M.-C.), Junta Provincial de Bizkaia-AECC (to M.L.M.-C.), AECC (T.C.D.); Basque Department of Industry, Tourism and Trade (Etortek) (A.C.), the BBVA foundation (A.C.), Fundacion AstraZeneca (R.N.) Centro de Investigacion Biomedica en Red (CIBER) de Fisiopatologia de la Obesidad y Nutricion (CIBERobn). CIBERobn is an initiative of the Instituto de Salud Carlos III (ISCIII) of Spain, which is supported by FEDER funds. The participation of A.C. and A.Z.-L. as part of CIBERONC was co-funded with FEDER funds. The research leading to these results has also received funding from the European Community's Seventh Framework Programme under the following grant: A.C.: ERC StG-336343; R.N.: ERC StG-281408 and G.S.: ERC StG-260464.S