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. / 2019-06-12T00:00:00Z

GPR17, a uracil nucleotide cysteinyl leukotriene receptor, belongs to the GPCR (G protein coupled receptor) family. It has been shown recently that inhibiting this protein in the nervous system in mice can lead to blockage of oligodendrocyte maturation, which supports myelin repair. Interestingly, our laboratory found GPR17 in thrombocytes. However, we do not know whether it has any function in thrombocyte aggregation or the nature of the ligand. In this paper, we studied the role of GPR17 in hemostasis, which is a fundamental defense mechanism in the event of injury. Using zebrafish as a model system, our laboratory has studied specifically thrombocytes, which play a significant role in hemostasis. The major reasons to use zebrafish as a model system are that their thrombocytes are functionally equivalent to human platelets, the adult fish are amenable to knockdown experiments, and they are readily available in the market. This study was performed by using a piggy back knockdown method where we used a chemical hybrid of control morpholino and an antisense oligonucleotide sequence leads to the degradation the mRNA for GPR17. After knockdown GPR17 in thrombocytes, the percent difference of the thrombocytes aggregation between the control and knockdown blood samples was measured by flow cytometry. We used various thrombocyte agonists to study differences in aggregation between the control and knockdown blood samples. The study showed that knockdown of GPR17 resulted in no significant differences in percent thrombocyte aggregation between control and agonist treated samples except for a slight increase in collagen-treated samples. Thus, it appears that GPR17 has no significant role in hemostasis.