María Mar Roca-Rodríguez1, Rajaa El Bekay1, Lourdes Garrido-Sanchez1, María Gómez-Serrano1, Leticia Coin-Aragüez1, Wilfredo Oliva-Olivera1, Said Lhamyani1, Mercedes Clemente-Postigo1, Eva García-Santos1, Resi de Luna Diaz1, Elena M Yubero-Serrano1, José M Fernández Real1, Belén Peral1, Francisco J Tinahones1. 1. Unidad de Gestión Clínica Endocrinología y Nutrición (M.M.R.R., R.E., L.G.S., L.C.A., W.O.O., S.L., M.C.P., F.J.T.), Instituto de Investigación Biomédica de Málaga, Complejo Hospitalario de Málaga (Virgen de la Victoria), Universidad de Málaga, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Málaga, Spain; Instituto de Investigaciones Biomédicas Alberto Sols (M.G.S., E.G.S., B.P.), Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain; Servicio de Cirugía General y Digestiva (R.d.L.D.), Hospital Universitario Virgen de la Victoria, Málaga, Spain; Lipids and Atherosclerosis Unit (E.M.Y.S.), IMIBIC/Reina Sofia University Hospital/University of Córdoba and CIBEROBN, Instituto de Salud Carlos III, Córdoba, Spain; and Departamento de Diabetes, Endocrinología y Nutrición (J.M.F.R.), Institut d'Investigació Biomèdica de Girona, CIBEROBN e ISCIII, Girona, Spain.
Abstract
OBJECTIVE: This study aimed to define the potential role of PTHrP on adipogenic regulation and to analyze its relationship with obesity and insulin resistance. DESIGN: This was a cross-sectional study in which visceral (VAT) and subcutaneous (SAT) adipose tissue were extracted from 19 morbidly obese, 10 obese, and 10 lean subjects. PTHrP mRNA levels were measured in VAT and SAT. VAT mesenchymal stem cells and 3T3-L1 cells were differentiated into adipocytes in presence or absence of PTHrP siRNA. PTHrP mRNA and protein levels as well as adipogenic markers were evaluated by Western blotting or qPCR. Immunohistochemistry and immunofluorescence procedures were used for PTHrP intracellular localization. RESULTS: Both human VAT and SAT express PTHrP protein mainly in the nucleolar compartment of stromal vascular fraction cells. The highest levels of PTHrP mRNA and protein expression were detected in undifferentiated mesenchymal cells and progressively decreased during adipogenesis. Remarkably, adipogenic differentiation in human mesenchymal stem cells (A-hMSC) was significantly impaired in a pthrp knockdown. PTHrP seems to be related to obesity-associated insulin resistance (IR), given that we found that PTHrP mRNA expression was higher in VAT from morbidly obese with a low IR degree (MO-L-IR) subjects than those from morbidly obese with a high IR degree (MO-H-IR) and lean subjects, and correlated positively with body mass index and hip circumference. We also found that A-hMSC from MO-L-IRs displayed higher adipogenic capacity than those from both MO-H-IRs and leans. In addition, adipogenesis was impaired in VAT from MO-H-IRs, given that mRNA expression levels of key adipogenic regulators were lower than those from MO-L-IR subjects. CONCLUSIONS: PTHrP could be a potential new therapeutic target for the reprograming of adipogenesis and adipose tissue expansion, thus possibly ameliorating the metabolic syndrome in obese subjects.
OBJECTIVE: This study aimed to define the potential role of PTHrP on adipogenic regulation and to analyze its relationship with obesity and insulin resistance. DESIGN: This was a cross-sectional study in which visceral (VAT) and subcutaneous (SAT) adipose tissue were extracted from 19 morbidly obese, 10 obese, and 10 lean subjects. PTHrP mRNA levels were measured in VAT and SAT. VAT mesenchymal stem cells and 3T3-L1 cells were differentiated into adipocytes in presence or absence of PTHrP siRNA. PTHrP mRNA and protein levels as well as adipogenic markers were evaluated by Western blotting or qPCR. Immunohistochemistry and immunofluorescence procedures were used for PTHrP intracellular localization. RESULTS: Both human VAT and SAT express PTHrP protein mainly in the nucleolar compartment of stromal vascular fraction cells. The highest levels of PTHrP mRNA and protein expression were detected in undifferentiated mesenchymal cells and progressively decreased during adipogenesis. Remarkably, adipogenic differentiation in human mesenchymal stem cells (A-hMSC) was significantly impaired in a pthrp knockdown. PTHrP seems to be related to obesity-associated insulin resistance (IR), given that we found that PTHrP mRNA expression was higher in VAT from morbidly obese with a low IR degree (MO-L-IR) subjects than those from morbidly obese with a high IR degree (MO-H-IR) and lean subjects, and correlated positively with body mass index and hip circumference. We also found that A-hMSC from MO-L-IRs displayed higher adipogenic capacity than those from both MO-H-IRs and leans. In addition, adipogenesis was impaired in VAT from MO-H-IRs, given that mRNA expression levels of key adipogenic regulators were lower than those from MO-L-IR subjects. CONCLUSIONS:PTHrP could be a potential new therapeutic target for the reprograming of adipogenesis and adipose tissue expansion, thus possibly ameliorating the metabolic syndrome in obese subjects.