The Role of Microtubules and Microfilaments in the Invasion of Eukaryotic Cells by Bacteria Serratia Grimesii and Serratia Proteamaculans

Objective: Serratia are opportunistic Gram-negative bacteria. Some species of these bacteria (including Serratia grimesi i and Serratia proteamaculans ) have been shown to cause diseases. It has been reported that S. grimesii and S. proteamaculans are able to invade non-phagocytic human cells. Bacterial invasion of host cells may be accompanied by both microfilament and microtubule rearrangements. Material and methods: In this study, we quantitatively compared the contribution of actin and microtubule rearrangements to the invasion intensity of S. grimesii and S. proteamaculans into M-HeLa and Caco-2 cells using the inhibitory assay. Results and discussion: We found that inhibition of actin cytoskeletal rearrangements by cytochalasin D did not significantly affect cell sensitivity to S. grimesii , but resulted in a two-fold increase in S. proteamaculans invasion into M-HeLa cells. Conclusions: We suggest that this effect may be related to the induction of cortical actin polymerization during incubation of M-HeLa cells with S. proteamaculans . Actin polymerization possibly takes place with the participation of type IV protein secretion system proteins found in S. proteamaculans but not in S. grimesii . Microtubules of epithelial cells play an important role in the internalization of S. grimesii and S. proteamaculans bacteria, since blocking their functions with colchicine and paclitaxel reduced the number of intracellular bacteria several-fold.