Suppression of HIF-1α transcription activity prevents Golgi Condensation under hypoxia through the Proteasomal degradation of GM130

Abstract

Golgi apparatus is a dynamic organelle which the structure is distinguished into three different types: flattened, condensed and fragmented. Even though the Golgi has various structure, the structure under hypoxia, the absence of oxygen, is poorly reported. Here, we validate that the Golgi is condensed and contracted under hypoxia rather than maintaining flattened morphology considered as a regular shape. Interestingly, suppression of Hypoxia inducible factor- I alpha (HIF-1α) prevents the structural abnormality of the Golgi. Moreover, we validate that the transcriptional activation of HIF-1α is essential to promote the Golgi condensation using by several mutated HIF-1α. In addition, we proposed a mechanism that GM130, a Golgi structural protein, is degraded by proteasome under HIF-1α activation condition. Ubiquitinated GM130 for proteasomal degradation is prevented by the depletion of HIF-1α. These results compromise that the Golgi condensation is promoted by activation of HIF-1α under hypoxia, and this transcriptional factor induces proteasomal degradation of GM130.