Expression and subcellular localization of mammalian formin Fhod3 in the embryonic and adult heart

Meikun Kan-o, Ryu Takeya, Kenichiro Taniguchi, Yoshihisa Tanoue, Ryuji Tominaga, Hideki Sumimoto

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The formin family proteins play pivotal roles in actin filament assembly via the FH2 domain. The mammalian formin Fhod3 is highly expressed in the heart, and its mRNA in the adult heart contains exons 11, 12, and 25, which are absent from non-muscle Fhod3 isoforms. In cultured neonatal cardiomyocytes, Fhod3 localizes to the middle of the sarcomere and appears to function in its organization, although it is suggested that Fhod3 localizes differently in the adult heart. Here we show, using immunohistochemical analysis with three different antibodies, each recognizing distinct regions of Fhod3, that Fhod3 localizes as two closely spaced bands in middle of the sarcomere in both embryonic and adult hearts. The bands are adjacent to the M-line that crosslinks thick myosin filaments at the center of a sarcomere but distant from the Z-line that forms the boundary of the sarcomere, which localization is the same as that observed in cultured cardiomyocytes. Detailed immunohistochemical and immuno-electron microscopic analyses reveal that Fhod3 localizes not at the pointed ends of thin actin filaments but to a more peripheral zone, where thin filaments overlap with thick myosin filaments. We also demonstrate that the embryonic heart of mice specifically expresses the Fhod3 mRNA isoform harboring the three alternative exons, and that the characteristic localization of Fhod3 in the sarcomere does not require a region encoded by exon 25, in contrast to an essential role of exons 11 and 12. Furthermore, the exon 25-encoded region appears to be dispensable for actin-organizing activities both in vivo and in vitro, albeit it is inserted in the catalytic FH2 domain.

Original languageEnglish
Article numbere34765
JournalPloS one
Volume7
Issue number4
DOIs
Publication statusPublished - Apr 16 2012

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Sarcomeres
sarcomeres
exons
Exons
heart
Actins
Myosins
myosin
microfilaments
Actin Cytoskeleton
Cardiac Myocytes
RNA Isoforms
active sites
actin
Catalytic Domain
Protein Isoforms
electrons
Electrons
Messenger RNA
antibodies

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Expression and subcellular localization of mammalian formin Fhod3 in the embryonic and adult heart. / Kan-o, Meikun; Takeya, Ryu; Taniguchi, Kenichiro; Tanoue, Yoshihisa; Tominaga, Ryuji; Sumimoto, Hideki.

In: PloS one, Vol. 7, No. 4, e34765, 16.04.2012.

Research output: Contribution to journalArticle

Kan-o, Meikun ; Takeya, Ryu ; Taniguchi, Kenichiro ; Tanoue, Yoshihisa ; Tominaga, Ryuji ; Sumimoto, Hideki. / Expression and subcellular localization of mammalian formin Fhod3 in the embryonic and adult heart. In: PloS one. 2012 ; Vol. 7, No. 4.
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