title: PKA regulatory subunit R2B is required for murine and human adipocyte differentiation.
abstract: ADIPOGENESIS IS A COMPLEX PROCESS MODULATED BY SEVERAL FACTORS, INCLUDING CAMP SIGNALING. THE MAIN CAMP TARGET IS PROTEIN KINASE A (PKA), A TETRAMERIC ENZYME WITH FOUR REGULATORY SUBUNITS SHOWING TISSUE-SPECIFIC EXPRESSION AND FUNCTION: PRKAR2B is the main regulatory subunit in adipose tissue in mice and in adult humans. This study aimed to evaluate the expression of PKA regulatory subunits in human adipose tissue during fetal development and to investigate their role in the differentiation of 3T3-L1 and primary human preadipocytes. The expression of PKA regulatory subunits was evaluated in fetal adipose tissue (immunohistochemistry) and in cultured 3T3-L1 and primary human preadipocytes (western blot analysis). Cultured cells were transiently transfected with siRNA against PRKAR2B and induced to differentiate. Differentiation was evaluated by intracellular triglyceride staining (Oil Red O) and expression of molecular markers of adipocyte differentiation. In this study, we found that PRKAR2B is the main regulatory subunit in human adipose tissue during fetal development, from 12 weeks of gestation to the end of gestation, as well as in 3T3-L1 and primary human preadipocytes. The expression of PRKAR2B increases progressively during in vitro differentiation. The silencing of PRKAR2B abolishes the increase in the expression of peroxisome proliferator-activated receptor gamma (PPARγ (PPARG)), fatty acid synthase, aP2 (FABP4), and lipoprotein lipase, as well as intracellular triglyceride accumulation, resulting in impaired adipocyte differentiation in both mouse and human cell systems. In conclusion, PRKAR2B is the key PKA regulatory subunit involved in mouse and human adipose tissue development. The physiological increase in the expression of PRKAR2B is an essential event in adipogenesis in both mice and humans, and it might represent a possible target for future strategies for obesity treatment.
authors.affiliation: Endocrinology and Diabetology UnitDepartment of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Pad.Granelli, Via F. Sforza, 35, 20122 Milan, Italy Diabetology and Metabolic Disease UnitIRCCS Policlinico San Donato, San Donato Milanese, Italy Endocrinology UnitIRCCS Policlinico S.Donato, Department of Biomedical Sciences for Health, University of Milan, Milan, Italy Unit of Human PathologyDepartment of Health Sciences, San Paolo Hospital Medical School, University of Milan, Milano, Italy Surgical DepartmentOspedale Sacra Famiglia Fatebenefratelli, Erba, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Peverelli
authors.forename: Federica
authors.initials: F
authors.lastname: Ermetici
authors.forename: Sabrina
authors.initials: S
authors.lastname: Corbetta
authors.forename: Ettore
authors.initials: E
authors.lastname: Gozzini
authors.forename: Laura
authors.initials: L
authors.lastname: Avagliano
authors.forename: Marco A
authors.initials: MA
authors.lastname: Zappa
authors.forename: Gaetano
authors.initials: G
authors.lastname: Bulfamante
authors.forename: Paolo
authors.initials: P
authors.lastname: Beck-Peccoz
authors.forename: Anna
authors.initials: A
authors.lastname: Spada
authors.forename: Giovanna
authors.initials: G
authors.lastname: Mantovani
keywords: PKA; adipocytes; cAMP; differentiation