Premature remodeling of fat body and fat mobilization triggered by platelet-derived growth factor/VEGF receptor in Drosophila [Research]

In Drosophila, fat body remodeling accompanied with fat mobilization is an ecdysone-induced dynamic process that only occurs during metamorphosis. Here, we show that the activated Drosophila platelet-derived growth factor/VEGF receptor (PVR) is sufficient to induce shape changes in the fat body, from thin layers of tightly conjugated polygonal cells to clusters of disaggregated round-shaped cells. These morphologic changes are reminiscent of those seen during early pupation upon initiation of fat body remodeling. Activation of PVR also triggers an early onset of lipolysis and mobilization of internal storage as revealed by the appearance of small lipid droplets and up-regulated lipolysis-related genes. We found that PVR displays a dynamic expression pattern in the fat body and peaks at the larval-prepupal transition under the control of ecdysone signaling. Removal of PVR, although it does not prevent ecdysone-induced fat body remodeling, causes ecdysone signaling to be up-regulated. Our data reveal that PVR is active in a dual-secured mechanism that involves an ecdysone-induced fat body remodeling pathway and a reinforced PVR pathway for effective lipid mobilization. Ectopic expression of activated c-kit—the mouse homolog of PVR in the Drosophila fat body—also results in a similar phenotype. This may suggest a novel function of c-kit as it relates to lipid metabolism in mammals.—Zheng, H., Wang, X., Guo, P., Ge, W., Yan, Q., Gao, W., Xi, Y., Yang, X. Premature remodeling of fat body and fat mobilization triggered by platelet-derived growth factor/VEGF receptor in Drosophila.

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