1
|
Hardin WR, Alas GCM, Taparia N, Thomas EB, Steele-Ogus MC, Hvorecny KL, Halpern AR, Tůmová P, Kollman JM, Vaughan JC, Sniadecki NJ, Paredez AR. The Giardia ventrolateral flange is a lamellar membrane protrusion that supports attachment. PLoS Pathog 2022; 18:e1010496. [PMID: 35482847 PMCID: PMC9089883 DOI: 10.1371/journal.ppat.1010496] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/10/2022] [Accepted: 04/04/2022] [Indexed: 12/01/2022] Open
Abstract
Attachment to the intestinal epithelium is critical to the lifestyle of the ubiquitous parasite Giardia lamblia. The ventrolateral flange is a sheet-like membrane protrusion at the interface between parasites and attached surfaces. This structure has been implicated in attachment, but its role has been poorly defined. Here, we identified a novel actin associated protein with putative WH2-like actin binding domains we named Flangin. Flangin complexes with Giardia actin (GlActin) and is enriched in the ventrolateral flange making it a valuable marker for studying the flanges' role in Giardia biology. Live imaging revealed that the flange grows to around 1 μm in width after cytokinesis, then remains uniform in size during interphase, grows in mitosis, and is resorbed during cytokinesis. A flangin truncation mutant stabilizes the flange and blocks cytokinesis, indicating that flange disassembly is necessary for rapid myosin-independent cytokinesis in Giardia. Rho family GTPases are important regulators of membrane protrusions and GlRac, the sole Rho family GTPase in Giardia, was localized to the flange. Knockdown of Flangin, GlActin, and GlRac result in flange formation defects. This indicates a conserved role for GlRac and GlActin in forming membrane protrusions, despite the absence of canonical actin binding proteins that link Rho GTPase signaling to lamellipodia formation. Flangin-depleted parasites had reduced surface contact and when challenged with fluid shear force in flow chambers they had a reduced ability to remain attached, confirming a role for the flange in attachment. This secondary attachment mechanism complements the microtubule based adhesive ventral disc, a feature that may be particularly important during mitosis when the parental ventral disc disassembles in preparation for cytokinesis. This work supports the emerging view that Giardia's unconventional actin cytoskeleton has an important role in supporting parasite attachment.
Collapse
Affiliation(s)
- William R. Hardin
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Germain C. M. Alas
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Nikita Taparia
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | - Elizabeth B. Thomas
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Melissa C. Steele-Ogus
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Kelli L. Hvorecny
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Aaron R. Halpern
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Pavla Tůmová
- Institute of Immunology and Microbiology, 1 Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Nathan J. Sniadecki
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
- Bioengineering, University of Washington, Seattle, Washington, United States of America
- Lab Medicine & Pathology, University of Washington, Seattle, Washington, United States of America
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington, United States of America
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Alexander R. Paredez
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| |
Collapse
|
2
|
Beussman KM, Rodriguez ML, Leonard A, Taparia N, Thompson CR, Sniadecki NJ. Micropost arrays for measuring stem cell-derived cardiomyocyte contractility. Methods 2016; 94:43-50. [PMID: 26344757 PMCID: PMC4761463 DOI: 10.1016/j.ymeth.2015.09.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 12/14/2022] Open
Abstract
Stem cell-derived cardiomyocytes have the potential to be used to study heart disease and maturation, screen drug treatments, and restore heart function. Here, we discuss the procedures involved in using micropost arrays to measure the contractile forces generated by stem cell-derived cardiomyocytes. Cardiomyocyte contractility is needed for the heart to pump blood, so measuring the contractile forces of cardiomyocytes is a straightforward way to assess their function. Microfabrication and soft lithography techniques are utilized to create identical arrays of flexible, silicone microposts from a common master. Micropost arrays are functionalized with extracellular matrix protein to allow cardiomyocytes to adhere to the tips of the microposts. Live imaging is used to capture videos of the deflection of microposts caused by the contraction of the cardiomyocytes. Image analysis code provides an accurate means to quantify these deflections. The contractile forces produced by a beating cardiomyocyte are calculated by modeling the microposts as cantilever beams. We have used this assay to assess techniques for improving the maturation and contractile function of stem cell-derived cardiomyocytes.
Collapse
Affiliation(s)
- Kevin M Beussman
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Marita L Rodriguez
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Andrea Leonard
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Nikita Taparia
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Curtis R Thompson
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Nathan J Sniadecki
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA.
| |
Collapse
|