Cat and mouth game: genetic influences on initiation and progression of feline tooth resorption | A cat and mouth game: genetic influences on initiation and progression of feline tooth resorption

Feline tooth resorption (TR) is a painful and progressive disease characterised by the destruction of mineralised tissue. This is caused by the dysregulation of odontoclasts; specialised cells which resorb teeth and responsible for tooth shedding, sharing many similarities with osteoclast, bone resorbing cells. TR is one of the most common dental problems found in cats; affecting 29%-70% of the domestic cat population. Currently, there are no effective treatments for TR; tooth extraction or coronal amputation are the only solutions. This is due to the aetiology of TR remaining unknown. Various factors such as genetic, inflammatory, and mechanical factors have been implicated in the development of TR but is still being investigated. The highest prevalence of TR is observed in pure bred cats, implying genetic cause of odontoclast dysregulation. The aim of this MSc project was to investigate the expression of genes by odontoclast within TR affected and unaffected samples and their function in resorption activity. Using data from transcriptome analysis by RNA sequencing, many differentially genes were identified between TR affected and unaffected cats. To localise this differential expression, feline dental samples were collected to localise the expression of specific differentially expressed genes within affected samples. Immunohistochemistry was performed to stain for targets MMP9, CTSK, and P2XR4 which co-localised with tartrate resistant acid phosphatase activity found in osteoclasts/odontoclasts in resorptive lesions on TR affected teeth. To elucidate the role of MMP9, CTSK, and P2XR4 in osteoclast/odontoclast differentiation and resorption, osteoclasts were transfected with siRNA via electroporation to target these three genes using an established protocol for deriving osteoclasts from feline bone marrow in vitro. Cells were seeded onto hydroxyapatite covered wells plates to assess osteoclast differentiation and resorptive activity. RNA extraction and quantitative PCR was performed on transfected cells to investigate the effect of siRNA on MMP9, CTSK, and P2XR4 expression. Through further bioinformatics analysis of RNAseq data, a large number of single nucleotide polymorphisms (SNPs) were found and impact on gene function was predicted. The results from this study indicate key components of odontoclast formation in TR positive teeth and their associated pathways. Further testing of candidate genes and assessing their downstream products may provide potential therapeutic targets for feline TR using the methods and results indicated in this study.