title: Differential role of nonmuscle myosin II isoforms during blebbing of MCF-7 cells.
abstract: Bleb formation has been correlated with nonmuscle myosin II (NM-II) activity. Whether three isoforms of NM-II (NM-IIA, -IIB and -IIC) have the same or differential roles in bleb formation is not well understood. Here we report that ectopically expressed, GFP-tagged NM-II isoforms exhibit different types of membrane protrusions, such as multiple blebs, lamellipodia, combinations of both, or absence of any such protrusions in MCF-7 cells. Quantification suggests that 50% of NM-IIA-GFP-, 29% of NM-IIB-GFP-, and 19% of NM-IIC1-GFP-expressing MCF-7 cells show multiple bleb formation, compared with 36% of cells expressing GFP alone. Of interest, NM-IIB has an almost 50% lower rate of dissociation from actin filament than NM-IIA and -IIC1 as determined by FRET analysis both at cell and bleb cortices. We induced bleb formation by disruption of the cortex and found that all three NM-II-GFP isoforms can reappear and form filaments but to different degrees in the growing bleb. NM-IIB-GFP can form filaments in blebs in 41% of NM-IIB-GFP-expressing cells, whereas filaments form in only 12 and 3% of cells expressing NM-IIA-GFP and NM-IIC1-GFP, respectively. These studies suggest that NM-II isoforms have differential roles in the bleb life cycle.
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Sumit K
authors.initials: SK
authors.lastname: Dey
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Raman K
authors.initials: RK
authors.lastname: Singh
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Shyamtanu
authors.initials: S
authors.lastname: Chattoraj
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Shekhar
authors.initials: S
authors.lastname: Saha
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai 400076, India.
authors.forename: Alakesh
authors.initials: A
authors.lastname: Das
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
authors.affiliation: Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Sengupta
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai 400076, India.
authors.forename: Shamik
authors.initials: S
authors.lastname: Sen
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India bcssj@iacs.res.in.
authors.forename: Siddhartha S
authors.initials: SS
authors.lastname: Jana
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D022081:Cell Surface Extensions / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D024507:Nonmuscle Myosin Type IIA / Q000378:metabolism*; D024501:Nonmuscle Myosin Type IIB / Q000378:metabolism*; D020033:Protein Isoforms; D011554:Pseudopodia / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; D024507:Nonmuscle Myosin Type IIA; D024501:Nonmuscle Myosin Type IIB