Regionalization of browning revealed by whole subcutaneous adipose tissue imaging

Corinne Barreau (1) , Elodie Labit (1) , Christophe Guissard (1) , Jacques Rouquette (2) , Marie-Laure Boizeau (2) , Souleymane Gani Koumassi (2) , Audrey Carrière (1) , Yannick Jeanson (1) , Sandra Berger-Müller (1) , Cécile Dromard (1) , Franck Plouraboué (3) , Louis Casteilla (1) , Anne Lorsignol (1)

1 STROMALab
2 ITAV - Institut des Technologies Avancées en sciences du Vivant
3 IMFT - Institut de mécanique des fluides de Toulouse

Objective: White and brown adipose tissues play a major role in the regulation of metabolic functions. With the explosion of obesity and metabolic disorders, the interest in adipocyte biology is growing constantly. While several studies have demonstrated functional differences between adipose fat pads, especially in their involvement in metabolic diseases, there are no data available on possible heterogeneity within an adipose depot. Methods: This study investigated the three-dimensional (3-D) organization of the inguinal fat pad in adult mice by combining adipose tissue clearing and autofluorescence signal acquisition by confocal microscopy. In addition, the study analyzed the expression of genes involved in adipocyte biology and browning at the mARN and protein levels in distinct areas of the inguinal adipose tissue, in control conditions and after cold exposure. Results: Semiautomated 3-D image analysis revealed an organization of the fat depot showing two regions: the core was structured into segmented lobules, whereas the periphery appeared unsegmented. Perilipin immunostaining showed that most of the adipocytes located in the core region had smaller lipid droplets, suggesting a brown-like phenotype. qPCR analysis showed a higher expression of the browning markers Ucp1, Prdm16, Ppargc1a, and Cidea in the core region than at the periphery. Finally, cold exposure induced upregulation of thermogenic gene expression associated with an increase of UCP1 protein, specifically in the core region of the inguinal fat depot. Conclusions: Altogether, these data demonstrate a structural and functional heterogeneity of the inguinal fat pad, with an anatomically restricted browning process in the core area.

Mots clés: Lobules; Segmentation; Adipose tissue.

Domaines: Mécanique des fluides [physics.class-ph]

Corinne Barreau, Elodie Labit, Christophe Guissard, Jacques Rouquette, Marie-Laure Boizeau, et al.. Regionalization of browning revealed by whole subcutaneous adipose tissue imaging. Obesity, 2016, vol. 00 (n° 00), pp. 1-9. ⟨10.1002/oby.21455⟩. ⟨hal-01299930⟩