Identification of Novel Protein Targets of Dimethyl Fumarate Modification in Neurons and Astrocytes Reveal Actions Independent of Keap1 Activation

ABSTRACT: The fumarate ester dimethyl fumarate (DMF) has been introduced recently for the treatment of relapsing remitting multiple sclerosis (RRMS), a chronic inflammatory condition resulting in neuronal demyelination and axonal loss. The complete mechanism of DMF action is unknown, but involves the depletion of intracellular glutathione and modification of thiols on Kelch-like ECH-associated protein 1 (Keap1), which in turn induces the expression of antioxidant response element genes. Previous work by our laboratory has shown that DMF reacts with a wide range of protein thiols in adipocytes, detected following ester hydrolysis by an antibody recognizing succinated proteins. We proposed that other intracellular thiol residues may also be irreversibly modified by DMF in neurons and astrocytes. DMF treatment of primary rodent neurons and astrocytes, as well as differentiated N1E-115 cells, resulted in the modification of 24 novel target proteins by mass spectrometry. Using this approach, we confirmed the identification and site of modification of the identified proteins, which include cofilin-1, tubulin and collapsin response mediator protein 2 (CRMP2). An in vitro functional assay that measures the ability of cofilin-1 to sever the actin cytoskeleton demonstrated that DMF-modified cofilin-1 loses activity and generates less monomeric actin, potentially inhibiting cofilin’s cytoskeletal remodeling activity; an effect that could be beneficial in the modulation of myelination during RRMS. DMF modification of tubulin did not significantly impact axonal lysosomal trafficking. The oxygen consumption rate of N1E-115 neurons and the levels of proteins related to mitochondrial energy production were only slightly affected by the highest doses of DMF, confirming that DMF treatment does not impair cellular respiratory function. In summary, we demonstrate that in addition to the stimulation of the antioxidant response, DMF resulted in electrophilic modification of novel protein targets that provide new insight on the mechanisms supporting the neuroprotective and re-myelination benefits associated with DMF treatment.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Rattus Norvegicus (rat) Mus Musculus (mouse)

TISSUE(S): Brain, Neuron, Permanent Cell Line Cell, Cell Culture, Astrocyte

DISEASE(S): Relapsing-remitting Multiple Sclerosis

SUBMITTER: Norma Frizzell  

LAB HEAD: Norma Frizzell

PROVIDER: PXD008314 | Pride | 2019-02-19

REPOSITORIES: Pride