Curcumin reduces alpha synuclein protein clumps in mice by targeting the UBC9 enzyme

A study on mice reveals that curcumin from turmeric protects dopamine neurons and reduces toxic protein buildup by targeting the UBC9 enzyme. Researchers at Nanjing Medical University and Sun Yat-Sen University have discovered that curcumin, a natural compound found in turmeric, can lessen brain changes and movement difficulties in a mouse model of Parkinson's. The study shows that curcumin works by turning down a specific cellular protein tagging system known as SUMOylation, which normally contributes to the toxic accumulation of alpha-synuclein. Alpha-synuclein is a protein that normally aids nerve cell communication, but in Parkinson's it misfolds into sticky aggregates that damage dopamine-producing neurons in a brain region called the substantia nigra. Cells use various chemical tags to control how proteins behave. One of these tags is called SUMO1, attached via a process known as SUMOylation. While protein tagging can sometimes protect cells, excessive SUMO1 tagging often stabilizes harmful alpha-synuclein aggregates and prevents the brain from clearing them away. To investigate whether curcumin could interrupt this harmful cycle, scientists injected lab-made alpha-synuclein clumps into the brains of mice to create a model of the condition. Six months later, once brain changes were established, the mice received a daily intravenous dose of curcumin at 25 milligrams per kilogram of body weight for one month. The treatment yielded noticeable improvements in both behaviour and brain structure. Mice treated with curcumin performed significantly better in physical mobility tests, such as remaining balanced on a rotating rod and moving around open areas, while also displaying fewer anxiety-like behaviours. At a microscopic level, curcumin helped preserve dopamine-producing nerve cells in the substantia nigra and boosted overall dopamine levels in the striatum, the area of the brain responsible for coordinating movement. The amount of phosphorylated alpha-synuclein, the toxic form found in brain protein clumps, dropped substantially following treatment. The researchers traced these protective effects directly to changes in cellular tagging. Curcumin selectively reduced the levels of an essential enzyme called UBC9, which acts as the main carrier for attaching SUMO1 tags to proteins. By lowering UBC9 activity, curcumin reduced harmful SUMOylation and allowed another tagging system, called ubiquitination, to take over. Ubiquitin tags act as molecular recycling markers, signaling the cell to break down and dispose of damaged alpha-synuclein before it can form lasting toxic clumps. Other enzymes involved in the tagging process, including SAE2 and PIAS1, remained unchanged, confirming that UBC9 is the specific primary target of curcumin. These findings highlight UBC9-mediated SUMOylation as a promising target for future therapies aimed at slowing down protein aggregation and protecting brain health.