Pantothenate Rescues Iron Accumulation in Pantothenate Kinase-Associated Neurodegeneration Depending on the Type of Mutation

Abstract

Neurodegeneration with brain iron accumulation (NBIA) is a group of inherited neurologic disorders in which iron accumulates in the basal ganglia resulting in progressive dystonia, spasticity, parkinsonism, neuropsychiatric abnormalities, and optic atrophy or retinal degeneration. The most prevalent form of NBIA is pantothenate kinase-associated neurodegeneration (PKAN) associated with mutations in the gene of pantothenate kinase 2 (PANK2), which is essential for coenzyme A (CoA) synthesis. There is no cure for NBIA nor is there a standard course of treatment. In the current work, we describe that fibroblasts derived from patients harbouring PANK2 mutations can reproduce many of the cellular pathological alterations found in the disease, such as intracellular iron and lipofuscin accumulation, increased oxidative stress, and mitochondrial dysfunction. Furthermore, mutant fibroblasts showed a characteristic senescent morphology. Treatment with pantothenate, the PANK2 enzyme substrate, was able to correct all pathological alterations in responder mutant fibroblasts with residual PANK2 enzyme expression. However, pantothenate had no effect on mutant fibroblasts with truncated/incomplete protein expression. The positive effect of pantothenate in particular mutations was also confirmed in induced neurons obtained by direct reprograming of mutant fibroblasts. Our results suggest that pantothenate treatment can stabilize the expression levels of PANK2 in selected mutations. These results encourage us to propose our screening model as a quick and easy way to detect pantothenate-responder patients with PANK2 mutations. The existence of residual enzyme expression in some affected individuals raises the possibility of treatment using high dose of pantothenate.

Down Regulation Of The Expression Of Mitochondrial Phosphopantetheinyl-Proteins In Pantothenate Kinase-Associated Neurodegeneration: Pathophysiological Consequences and Therapeutic Perspectives

“…Interestingly, supplementation with pantothenate (500µM), the substrate of the PANK2 enzyme, was able to stabilize the expression levels of the mutant enzyme in selected patients, P1 and P2, but not in P3 broblasts with a frame shift mutation ( Fig. 1a and 1b) (8). To further characterize the pathological consequences of CoA de ciency in PANK2 mutations, we then examined the expression of cytosolic and mitochondrial proteins carrying 4′-phosphopantetheine cofactors, an intermediate metabolite in the CoA biosynthesis pathway.…”

“…In a previous work, we analyzed PANK2 expression levels in broblast cell lines derived from three PKAN patients and three healthy subjects (8). Two PKAN patients, P1 and P2, harbouring compound heterozygous mutations and decreased PANK2 expression levels, while patient P3 carried a homozygous frame shift mutation that results in the complete lack of PANK2 expression (8).…”

“…Western blotting was performed using standard Methods described in previous manuscripts of the research group (8). After protein transfer, membranes were incubated with various primary antibodies diluted 1:1000, and then with the corresponding secondary antibody coupled to horseradish peroxidase at a 1:10000 dilution.…”

“…The enzyme alteration causes coenzyme A de ciency, mitochondria dysfunction and low energy production, intracellular iron accumulation, alterations in cell membranes renewal and impaired protection against oxidative damage, which provokes lipid peroxidation and pathological changes of cell membranes, and eventually cell demise (4,6). Altered mitochondrial membrane potential and defective mitochondrial respiration have been demonstrated in PANK2-defective neurons derived from KO mice (7) and in cellular models derived from PKAN patients (8)(9)(10). However, the precise pathological mechanisms involved in PKAN are not completely understood.…”

Phenotypic expression and founder effect of PANK2 c.1583C>T (p.T528M) mutation in Serbian pantothenate kinase-associated neurodegeneration patients

“…A genotype-phenotype correlation is not always clear because of the number of PANK2 rare variants in homozygous or compound heterozygous states. The majority of PANK2 mutations reduces or abolishes the activity of the enzyme, and recent therapeutic options are oriented toward treatment with pantothenate, the PANK2 enzyme substrate [15,16]. Results of in vitro studies suggest that such treatment can stabilize the expression levels of PANK2 only in selected mutation, underlining the importance of precise PANK2 genotypization in each PKAN case [16].…”