Abstract
Strains of uropathogenic Escherichia coli (UPEC) encode filamentous adhesive organelles called type 1 pili that promote bacterial colonization and invasion of the bladder epithelium. Type 1 pilus-mediated interactions with host receptors, including alpha3beta1 integrin, trigger localized actin rearrangements that lead to internalization of adherent bacteria via a zipper-like mechanism. Here we report that type 1 pilus-mediated bacterial invasion of bladder cells also requires input from host microtubules and histone deacetylase 6 (HDAC6), a cytosolic enzyme that, by deacetylating alpha-tubulin, can alter the stability of microtubules along with the recruitment and directional trafficking of the kinesin-1 motor complex. We found that disruption of microtubules by nocodazole or vinblastine treatment, as well as microtubule stabilization by taxol, inhibited host cell invasion by UPEC, as did silencing of HDAC6 expression or pharmacological inhibition of HDAC6 activity. Invasion did not require two alternate HDAC6 substrates, Hsp90 and cortactin, but was dependent upon the kinesin-1 light chain KLC2 and an upstream activator of HDAC6, aurora A kinase. These results indicate that HDAC6 and microtubules act as vital regulatory elements during the invasion process, possibly via indirect effects on kinesin-1 and associated cargos.