Chavey Carine, Boucher Jérémie, Monthouël-Kartmann Marie-Noëlle, Sage E Helene, Castan-Laurell Isabelle, Valet Philippe, Tartare-Deckert Sophie, Van Obberghen Emmanuel
Institut National de la Santé et de la Recherche Médicale U145, IFR 50, Avenue de Valombrose, 06107 Nice Cedex 2, France.
Obesity (Silver Spring). 2006 Nov;14(11):1890-7. doi: 10.1038/oby.2006.220.
To explore the regulation of secreted protein acidic and rich in cysteine (SPARC) expression and its role in adipose tissue.
We studied the regulation of SPARC expression in transgenic mice expressing the human beta3 and alpha2 adrenergic receptors on a murine beta3 adrenergic receptor null background that became obese under a high-fat diet mainly as a result of adipose tissue hyperplasia. Furthermore, we analyzed its expression in human adipose tissue and its regulation during adipocyte differentiation.
SPARC protein in adipose tissue was increased in obese transgenic mice compared with control mice, indicating that SPARC expression was associated with adipose tissue hyperplasia. Both SPARC mRNA and protein were detected in human adipose tissue. Comparing adipocytes and vascular stroma, we found that SPARC expression was mainly associated with the adipocyte fraction. Consistent with this, SPARC transcript increased during differentiation of human primary preadipocytes. 3T3-L1 preadipocytes showed an increase in SPARC expression in differentiated cells but with biphasic expression during the process. After induction in committed cells, SPARC mRNA and protein levels declined as differentiation began and returned to elevated levels in fully differentiated adipocytes.
SPARC expression correlated with adipose tissue hyperplasia and adipogenesis. Therefore, SPARC seems to play a role in adipose tissue physiology as it is involved in growth and differentiation.
探讨富含半胱氨酸的酸性分泌蛋白（SPARC）的表达调控及其在脂肪组织中的作用。
我们研究了在小鼠β3肾上腺素能受体缺失背景下表达人β3和α2肾上腺素能受体的转基因小鼠中SPARC表达的调控情况，这些小鼠在高脂饮食下主要由于脂肪组织增生而肥胖。此外，我们分析了其在人脂肪组织中的表达及其在脂肪细胞分化过程中的调控。
与对照小鼠相比，肥胖转基因小鼠脂肪组织中的SPARC蛋白增加，表明SPARC表达与脂肪组织增生有关。在人脂肪组织中检测到SPARC mRNA和蛋白。比较脂肪细胞和血管基质，我们发现SPARC表达主要与脂肪细胞部分相关。与此一致的是，人原代前脂肪细胞分化过程中SPARC转录本增加。3T3-L1前脂肪细胞在分化细胞中SPARC表达增加，但在此过程中呈双相表达。在定向细胞诱导后，随着分化开始，SPARC mRNA和蛋白水平下降，并在完全分化的脂肪细胞中恢复到升高水平。
SPARC表达与脂肪组织增生和脂肪生成相关。因此，SPARC似乎在脂肪组织生理学中发挥作用，因为它参与生长和分化。
