RESUMEN
OBJECTIVE: Reorganization of the extracellular matrix is a prerequisite for healthy adipose tissue expansion, whereas fibrosis is a key feature of adipose dysfunction and inflammation. However, very little is known about the direct effects of impaired cell-matrix interaction in adipocyte function and insulin sensitivity. The objective of this study was to determine whether integrin activity can regulate insulin sensitivity in adipocytes and thereby systemic metabolism. METHODS: We characterized integrin activity in adipose tissue and its consequences on whole-body metabolism using adipose-selective deletion of ß1 integrin (Itgb1adipo-cre) and Kindlin-2 (Kind2adipo-cre) in mice. RESULTS: We demonstrate that integrin signaling regulates white adipocyte insulin action and systemic metabolism. Consequently, loss of adipose integrin activity, similar to loss of adipose insulin receptors, results in a lipodystrophy-like phenotype and systemic insulin resistance. However, brown adipose tissue of Kind2adipo-cre and Itgb1adipo-cre mice is chronically hyperactivated and has increased substrate delivery, reduced endothelial basement membrane thickness, and increased endothelial vesicular transport. CONCLUSIONS: Thus, we establish integrin-extracellular matrix interactions as key regulators of white and brown adipose tissue function and whole-body metabolism.
Asunto(s)
Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Resistencia a la Insulina , Integrinas/metabolismo , Adipocitos Blancos/metabolismo , Animales , Proteínas del Citoesqueleto/genética , Proteínas del Citoesqueleto/metabolismo , Dieta , Dieta Alta en Grasa , Metabolismo Energético/efectos de los fármacos , Hígado Graso/metabolismo , Hígado Graso/patología , Femenino , Lipodistrofia/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Obesidad/genética , Obesidad/metabolismo , Transducción de Señal , Termogénesis/genéticaRESUMEN
The extracellular matrix is known to modulate cell adhesion and migration during tissue regeneration. However, the molecular mechanisms that fine-tune cells to extra-cellular matrix dynamics during regeneration of the peripheral nervous system remain poorly understood. Using the RSC96 Schwann cell line, we show that Sox2 directly controls fibronectin fibrillogenesis in Schwann cells in culture, to provide a highly oriented fibronectin matrix, which supports their organization and directional migration. We demonstrate that Sox2 regulates Schwann cell behaviour through the upregulation of multiple extracellular matrix and migration genes as well as the formation of focal adhesions during cell movement. We find that mouse primary sensory neurons and human induced pluripotent stem cell-derived motoneurons require the Sox2-dependent fibronectin matrix in order to migrate along the oriented Schwann cells. Direct loss of fibronectin in Schwann cells impairs their directional migration affecting the alignment of the axons in vitro. Furthermore, we show that Sox2 and fibronectin are co-expressed in proregenerative Schwann cells in vivo in a time-dependent manner during sciatic nerve regeneration. Taken together, our results provide new insights into the mechanisms by which Schwann cells regulate their own extracellular microenvironment in a Sox2-dependent manner to ensure the proper migration of neurons.