SM22 is required for the maintenance of actin-rich structures generated during bacterial infections
- Department of Biological Sciences, Simon Fraser University, 8888 University Dr Shrum Science Centre Rm B7239, Burnaby, BC, Canada V5A1S6 (United States)
- Department of Medicine, University of Chicago, 5841 S. Maryland Ave, MC6026, Rm BH-M644, Chicago, IL 60637 (United States)
Highlights: • SM22 colocalizes with actin at EPEC pedestals and L. monocytogenes comet tails, • SM22 depletion reduces EPEC pedestals and L. monocytogenes comet tail abundance, • SM22 overexpression enhances L. monocytogenes comet tail formation. The host actin cytoskeleton is utilized by an assortment of pathogenic bacteria to colonize and cause disease in their hosts. Two prominently studied actin-hijacking bacteria are enteropathogenic Escherichia coli (EPEC) and Listeria monocytogenes. EPEC form actin-rich pedestals atop its host cells to move across the intestinal epithelia, while Listeria monocytogenes generate branched actin networks arranged as actin clouds around the bacteria and as comet tails for propulsion within and amongst their host cells. Previous mass spectrometry analysis revealed that a member of the calponin family of actin-bundling proteins, transgelin/SM22 was enriched in EPEC pedestals. To validate that finding and examine the role of SM22 during infections, we initially immunolocalized SM22 in EPEC and L. monocytogenes infected cells, used siRNA to deplete SM22 and EGFP-SM22 to overexpress SM22, then quantified the alterations to the bacterially generated actin structures. SM22 concentrated at all bacterially-generated actin structures. Depletion of SM22 resulted in fewer pedestals and comet tails and caused comet tails to shorten. The decrease in comet tail abundance caused a proportional increase in actin clouds whereas overexpression of SM22 reversed the actin cloud to comet tail proportions and increased comet tail length, while not influencing EPEC pedestal abundance. Thus, we demonstrate that SM22 plays a role in regulating the transitions and morphological appearance of bacterially generated actin-rich structures during infections.
- OSTI ID:
- 23082693
- Journal Information:
- Experimental Cell Research, Journal Name: Experimental Cell Research Journal Issue: 1 Vol. 369; ISSN 0014-4827; ISSN ECREAL
- Country of Publication:
- United States
- Language:
- English
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