posted on 2023-12-08, 19:05authored byWei-Hsuan Wang, Yi-Chun Kao, Chiao-Hui Hsieh, Shin-Yu Tsai, Chantal Hoi Yin Cheung, Hsuan-Cheng Huang, Hsueh-Fen Juan
Mitochondrial division inhibitor 1 (Mdivi-1) is a well-known
synthetic
compound aimed at inhibiting dynamin-related protein 1 (Drp1) to suppress
mitochondrial fission, making it a valuable tool for studying mitochondrial
dynamics. However, its specific effects beyond Drp1 inhibition remain
to be confirmed. In this study, we employed integrative proteomics
and phosphoproteomics to delve into the molecular responses induced
by Mdivi-1 in SK-N-BE(2)C cells. A total of 3070 proteins and 1945
phosphorylation sites were identified, with 880 of them represented
as phosphoproteins. Among these, 266 proteins and 97 phosphorylation
sites were found to be sensitive to the Mdivi-1 treatment. Functional
enrichment analysis unveiled their involvement in serine biosynthesis
and extrinsic apoptotic signaling pathways. Through targeted metabolomics,
we observed that Mdivi-1 enhanced intracellular serine biosynthesis
while reducing the production of C24:1-ceramide. Within these regulated
phosphoproteins, dynamic dephosphorylation of proteasome subunit alpha
type 3 serine 250 (PSMA3-S250) occurred after Mdivi-1 treatment. Further
site-directed mutagenesis experiments revealed that the dephosphorylation-deficient
mutant PSMA3-S250A exhibited a decreased cell survival. This research
confirms that Mdivi-1’s inhibition of mitochondrial division
leads to various side effects, ultimately influencing cell survival,
rather than solely targeting Drp1 inhibition.