Elucidating the role of serine protease kallikrein 6 in oligodendrocyte maturation & myelination
O'Neill, Sharon M.
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Multiple sclerosis (MS) is a chronic central nervous system disease featuring exacerbations of inflammation and demyelination that cause progressively debilitating clinical effects over time. Current treatments for multiple sclerosis are limited in their ability to impact overall disease progression. Research aimed at generation of novel potential therapeutics for MS is needed. Recently, kallikrein 6 (KLK6), a member of the kallikrein (KLK) family of secreted serine proteases, was found to be elevated in the cerebrospinal fluid and brain of MS patients. The fifteen known tissue-based KLKs cleave proteins through a similar mechanism, but have different binding pocket specificity, diverse localization in human tissues, and multiple biological functions. KLKs have been linked to normal human physiology (e.g. KLK4, enamel formation) and disease (e.g. KLK3, prostate cancer). KLK6 is one of the highest expressed serine proteases in the healthy human brain and is expressed predominately in mature oligodendrocytes in both human and mouse brain. The role of KLK6 in oligodendrocyte maturation, myelination, and disease is not fully understood. To evaluate the role of KLK6 in oligodendrocyte maturation, I used a pluripotent in vitro primary cell system to assess the impact of exogenous KLK6 and modulators of the KLK6 pathway on oligodendrocyte maturation. I demonstrate that signaling through KLK6 decreases the number of mature oligodendrocytes in culture, whereas blockade of KLK6 signaling increases the number of mature oligodendrocytes in culture in the presence of triiodothyronine higher than either agent alone. This work suggests that KLK6 modulation impacts oligodendrocyte maturation. To understand the potential impact of KLK6 pathway inhibition on remyelination, I used the toxin cuprizone to induce demyelination in mice. I found that animals treated with a KLK6 inhibitor had increased myelin staining in the corpus callosum compared to vehicle-treated. This work suggests that KLK6 modulates oligodendrocyte maturation and myelination and may be relevant for improving myelin-related therapeutic outcomes, particularly in multiple sclerosis.