Functional assessment of Keratin 10 (KRT10) variants identified in patients with life-threatening bacterial infections

Abstract

Invasive bacterial infection is a leading cause of childhood mortality, accounting for a quarter of child deaths globally (Liu et al., 2015). Although numerous projects have focused on rare single- gene mutations in specific immune pathways predisposing individuals to invasive bacterial infection. Patients with these rare mutations are unable to produce factors that are essential to fighting the infection. Exome data from children (one month to 18 years) suffering from invasive bacterial infections were recruited during the study to identify new potential causative mutations. After undergoing gene enrichment analyses, these patients revealed mutations in protective immune signaling pathways involved in sensing invading bacteria. These variants affect the N- terminal and road domains, which interacts with different invasive bacteria such as Staphylococcus aureus. Since such an interaction is required for bacterial binding, the mutations may impact bacterial uptake, potentially contributing to life-threatening infection. We investigate rare damaging variants in the KRT10 gene that could result in KRT10 that enhances cellular attachment with an invasive bacterial infection. Nine missense KRT10 mutations introduced into the pCMV6-KRT10 wild-type plasmid using site-directed mutagenesis. Then, western blot was used to assess the impact of the variants on protein expression. Our findings show that KRT10 mutations express a protein to a similar level to wild-type in HEK293 cells. We investigated in vitro the effect of KRT10 missense mutation in bacterial adhesion and invasion. Based on the findings of the S.aureus adhesion and invasion assays our results provide a brief experimental explanation for some KRT10 missense mutations located in functional domains disturbing normal function, resulting in enhanced specific bacterial infections that lead to life-threatening cases.