Different contributions of nonmuscle myosin IIA and IIB to the organization of stress fiber subtypes in fibroblasts

Masahiro Kuragano, Taro Q.P. Uyeda, Keiju Kamijo, Yota Murakami, Masayuki Takahashi*, Yu Li Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Stress fibers (SFs) are contractile, force-generating bundled structures that can be classified into three subtypes, namely ventral SFs (vSFs), transverse arcs (TAs), and dorsal SFs. Nonmuscle myosin II (NMII) is the main component of SFs. This study examined the roles of the NMII isoforms NMIIA and NMIIB in the organization of each SF subtype in immortalized fibroblasts. Knockdown (KD) of NMIIA (a major isoform) resulted in loss of TAs from the lamella and caused the lamella to lose its flattened shape. Exogenous expression of NMIIB rescued this defect in TA formation. However, the TAs that formed on exogenous NMIIB expression in NMIIA-KD cells and the remaining TAs in NMIIB-KD cells, which mainly consisted of NMIIB and NMIIA, respectively, failed to rescue the defect in lamellar flattening. These results indicate that both isoforms are required for the proper function of TAs in lamellar flattening. KD of NMIIB resulted in loss of vSFs from the central region of the cell body, and this defect was not rescued by exogenous expression of NMIIA, indicating that NMIIA cannot replace the function of NMIIB in vSF formation. Moreover, we raised the possibility that actin filaments in vSFs are in a stretched conformation.

Original languageEnglish
Pages (from-to)911-922
Number of pages12
JournalMolecular biology of the cell
Issue number8
Publication statusPublished - 2018 Apr 15

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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