Polyamines Counteract Carbonate-Driven Proteasome Stalling in Alkaline Conditions

Abstract

Cancer cells tend to increase intracellular pH and, at the same time, are known to intensively produce and uptake polyamines such as spermine. Here, we show that various amines, including biogenic polyamines, boost the activity of proteasomes in a dose-dependent manner. Proteasome activity in the classical amine-containing buffers, such as 2-(N-morpholino)ethanesulfonic acid (MES), Tris, (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), glycylglycine, bis-Tris propane, and bicine, has a skewed distribution with a maximum at pH of 7.0–8.0. The activity of proteasomes in buffers containing imidazole and bis-Tris is maintained almost on the same level, in the pH range of 6.5–8.5. The third type of activation is observed in buffers based on the amino acids arginine and ornithine, as well as the natural polyamines spermine and spermidine. Proteasome activity in these buffers is dramatically increased at pH values greater than 7.5. Anionic buffers such as phosphate or carbonate, in contrast, inhibit proteasome activity during alkalization. Importantly, supplementation of a carbonate–phosphate buffer with spermine counteracts carbonate-driven proteasome stalling in alkaline conditions, predicting an additional physiological role of polyamines in maintaining the metabolism and survival of cancer cells.

At the Cutting Edge against Cancer: A Perspective on Immunoproteasome and Immune Checkpoints Modulation as a Potential Therapeutic Intervention

“…All these conditions lead to a decrease in protein quality control and make UPS a suitable target for cancer therapy [ 218 , 219 ]. Accordingly, a number of proteasome based-strategies have been proposed, spanning from (i) inhibition of proteasome proteolytic activity, (ii) modulation of the abundance of proteasome regulatory particles (i.e., 19S or PA28) and of their interaction with the 20S to (iii) modulation of the activity of enzymes involved in proteasome subunit post-translational modifications and (iv) interference with transport of natural low-molecular-weight proteasome activators (e.g., spermine) [ 62 , 226 , 227 , 228 , 229 , 230 , 231 , 232 ]. Additionally, a series of strategies targeting the ubiquitination cascade have been studied.…”

Biogenic Polyamines and Related Metabolites

“…To decrease the polyamine pool, OAZ1 binds to an ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, and targets it for ubiquitin-independent degradation by the 26S proteasome. In this Special Issue, Kudriaeva et al [ 8 ] demonstrate that spermine and spermidine boost the activity of proteasomes in a dose-dependent manner. This observation may be of interest for a better understanding of mechanisms of proteasome-mediated proteolysis and also for maintaining polyamine homeostasis in a cell.…”