Biomolecular alterations detected in multiple sclerosis skin fibroblasts using Fourier transform infrared spectroscopy.

Multiple sclerosis (MS) is the leading cause of non-traumatic disability in young adults. New avenues are needed to help predict individuals at risk for developing MS and aid in diagnosis, prognosis, and outcome of therapeutic treatments. Previously, we showed that skin fibroblasts derived from patients with MS have altered signatures of cell stress and bioenergetics, which likely reflects changes in their protein, lipid, and biochemical profiles. Here, we used Fourier transform infrared (FTIR) spectroscopy to determine if the biochemical landscape of MS skin fibroblasts were altered when compared to age- and sex-matched controls (CTRL). More so, we sought to determine if FTIR spectroscopic signatures detected in MS skin fibroblasts are disease specific by comparing them to amyotrophic lateral sclerosis (ALS) skin fibroblasts. Spectral profiling of skin fibroblasts from MS individuals suggests significant alterations in lipid and protein organization and homeostasis, which may be affecting metabolic processes, cellular organization, and oxidation status. Sparse partial least squares-discriminant analysis of spectral profiles show that CTRL skin fibroblasts segregate well from diseased cells and that changes in MS and ALS may be unique. Differential changes in the spectral profile of CTRL, MS, and ALS cells support the development of FTIR spectroscopy to detect biomolecular modifications in patient-derived skin fibroblasts, which may eventually help establish novel peripheral biomarkers.

Signatures of cell stress and altered bioenergetics in skin fibroblasts from patients with multiple sclerosis.

Multiple sclerosis (MS) is a central nervous system inflammatory demyelinating disease and the most common cause of non-traumatic disability in young adults. Despite progress in the treatment of the active relapsing disease, therapeutic options targeting irreversible progressive decline remain limited. Studies using skin fibroblasts derived from patients with neurodegenerative disorders demonstrate that cell stress pathways and bioenergetics are altered when compared to healthy individuals. However, findings in MS skin fibroblasts are limited. Here, we collected skin fibroblasts from 24 healthy control individuals, 30 patients with MS, and ten with amyotrophic lateral sclerosis (ALS) to investigate altered cell stress profiles. We observed endoplasmic reticulum swelling in MS skin fibroblasts, and increased gene expression of cell stress markers including BIP, ATF4, CHOP, GRP94, P53, and P21. When challenged against hydrogen peroxide, MS skin fibroblasts had reduced resiliency compared to ALS and controls. Mitochondrial and glycolytic functions were perturbed in MS skin fibroblasts while exhibiting a significant increase in lactate production over ALS and controls. Our results suggest that MS skin fibroblasts have an underlying stress phenotype, which may be disease specific. Interrogating MS skin fibroblasts may provide patient specific molecular insights and aid in prognosis, diagnosis, and therapeutic testing enhancing individualized medicine.

A conserved motif mediates both multimer formation and allosteric activation of phosphoglycerate mutase 5.

Phosphoglycerate mutase 5 (PGAM5) is an atypical mitochondrial Ser/Thr phosphatase that modulates mitochondrial dynamics and participates in both apoptotic and necrotic cell death. The mechanisms that regulate the phosphatase activity of PGAM5 are poorly understood. The C-terminal phosphoglycerate mutase domain of PGAM5 shares homology with the catalytic domains found in other members of the phosphoglycerate mutase family, including a conserved histidine that is absolutely required for catalytic activity. However, this conserved domain is not sufficient for maximal phosphatase activity. We have identified a highly conserved amino acid motif, WDXNWD, located within the unique N-terminal region, which is required for assembly of PGAM5 into large multimeric complexes. Alanine substitutions within the WDXNWD motif abolish the formation of multimeric complexes and markedly reduce phosphatase activity of PGAM5. A peptide containing the WDXNWD motif dissociates the multimeric complex and reduces but does not fully abolish phosphatase activity. Addition of the WDXNWD-containing peptide in trans to a mutant PGAM5 protein lacking the WDXNWD motif markedly increases phosphatase activity of the mutant protein. Our results are consistent with an intermolecular allosteric regulation mechanism for the phosphatase activity of PGAM5, in which the assembly of PGAM5 into multimeric complexes, mediated by the WDXNWD motif, results in maximal activation of phosphatase activity. Our results suggest the possibility of identifying small molecules that function as allosteric regulators of the phosphatase activity of PGAM5.