NANOG Plays a Hierarchical Role in the Transcription Network Regulating the Pluripotency and Plasticity of Adipose Tissue-Derived Stem Cells

Abstract

The stromal vascular cell fraction (SVF) of visceral and subcutaneous adipose tissue (VAT and SAT) has increasingly come into focus in stem cell research, since these compartments represent a rich source of multipotent adipose-derived stem cells (ASCs). ASCs exhibit a self-renewal potential and differentiation capacity. Our aim was to study the different expression of the embryonic stem cell markers <i>NANOG</i> (homeobox protein NANOG), <i>SOX2</i> (SRY (sex determining region Y)-box 2) and <i>OCT4</i> (octamer-binding transcription factor 4) and to evaluate if there exists a hierarchal role in this network in ASCs derived from both SAT and VAT. ASCs were isolated from SAT and VAT biopsies of 72 consenting patients (23 men, 47 women; age 45 ± 10; BMI between 25 ± 5 and 30 ± 5 range) undergoing elective open-abdominal surgery. Sphere-forming capability was evaluated by plating cells in low adhesion plastic. Stem cell markers CD90, CD105, CD29, CD31, CD45 and CD146 were analyzed by flow cytometry, and the stem cell transcription factors NANOG, SOX2 and OCT4 were detected by immunoblotting and real-time PCR. <i>NANOG</i>, <i>SOX2</i> and <i>OCT4</i> interplay was explored by gene silencing. ASCs from VAT and SAT confirmed their mesenchymal stem cell (MSC) phenotype expressing the specific MSC markers CD90, CD105, NANOG, SOX2 and OCT4. <i>NANOG</i> silencing induced a significant <i>OCT4</i> (70 ± 0.05%) and <i>SOX2</i> (75 ± 0.03%) downregulation, whereas <i>SOX2</i> silencing did not affect <i>NANOG</i> gene expression. Adipose tissue is an important source of MSC, and siRNA experiments endorse a hierarchical role of <i>NANOG</i> in the complex transcription network that regulates pluripotency.