Schisandrin B suppresses TGFβ1-induced stress fiber formation by inhibiting myosin light chain phosphorylation.
BACKGROUND
Schisandra chinensis fruit extract (SCE) has been used as a traditional oriental medicine for treating vascular diseases. However, the pharmacologic effects and mechanisms of SCE on vascular fibrosis are still largely unknown. Transforming growth factor β1 (TGFβ1)-mediated cellular changes are closely associated with the pathogenesis of vascular fibrotic diseases. Particularly, TGFβ1 induces actin stress fiber formation that is a crucial mechanism underlying vascular smooth muscle cell (VSMC) migration in response to vascular injury. In this study, we investigated the effect of SCE and its active ingredients on TGFβ1-induced stress fiber assembly in A7r5 VSMCs.


METHODS
To investigate pharmacological actions of SCE and its ingredients on TGFβ1-treated VSMCs, we have employed molecular and cell biological technologies, such as confocal microscopy, fluorescence resonance energy transfer, western blotting, and radiometric enzyme analyses.


RESULTS
We found that SCE inhibited TGFβ1-induced stress fiber formation and cell migration. Schisandrin B (SchB) showed the most prominent effect among the active ingredients of SCE tested. SchB reduced TGFβ1-mediated phosphorylation of myosin light chain, and this effect was independent of RhoA/Rho-associated kinase pathway. Fluorescence resonance energy transfer and radiometric enzyme assays confirmed that SchB inhibited myosin light chain kinase activity. We also showed that SchB decreased TGFβ1-mediated induction of α-smooth muscle actin by inhibiting Smad signaling.


CONCLUSIONS
The present study demonstrates that SCE and its active ingredient SchB suppressed TGFβ1-induced stress fiber formation at the molecular level. Therefore, our findings may help future investigations to develop multi-targeted therapeutic strategies that attenuate VSMC migration and vascular fibrosis.
Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Institute of Human-Environment Interface Biology, Seoul National University, Seoul 110-799, Republic of Korea.
Jung Nyeo
JN
Chun
Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Republic of Korea; Department of Medicine, University of Ulsan, College of Medicine, Seoul 138-736, Republic of Korea.
Sang-Yeob
SY
Kim
Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
Eun-Jung
EJ
Park
Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
Eun Jung
EJ
Kwon
Department of Biochemistry and Cell Biology, Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea.
Dong-Jun
DJ
Bae
Department of Biochemistry and Cell Biology, Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea.
In-San
IS
Kim
Department of Urology, Medical School and Institute for Medical Sciences, Chonbuk National University, Jeonju 561-712, Republic of Korea.
Hye Kyung
HK
Kim
Department of Urology, Medical School and Institute for Medical Sciences, Chonbuk National University, Jeonju 561-712, Republic of Korea.
Jong Kwan
JK
Park
Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
Sung Won
SW
Lee
Department of Biotechnology, Yeungnam University, Gyeongsan 712-749, Republic of Korea.
Hyun Ho
HH
Park
Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Institute of Human-Environment Interface Biology, Seoul National University, Seoul 110-799, Republic of Korea.
Insuk
I
So
Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Institute of Human-Environment Interface Biology, Seoul National University, Seoul 110-799, Republic of Korea. Electronic address: jhjeon2@snu.ac.kr.
Ju-Hong
JH
Jeon
D000199:Actins / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D034242:Cyclooctanes / Q000302:isolation & purification / Q000494:pharmacology; D005638:Fruit; D017705:Lignans / Q000302:isolation & purification / Q000494:pharmacology*; D008518:Medicine, East Asian Traditional; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects; D018994:Myosin Light Chains / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D011083:Polycyclic Compounds / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D032141:Schisandra / Q000737:chemistry*; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism; D022502:Stress Fibers / Q000187:drug effects* / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000494:pharmacology
D000199:Actins; D034242:Cyclooctanes; D017705:Lignans; D018994:Myosin Light Chains; D010936:Plant Extracts; D011083:Polycyclic Compounds; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; C015499:schizandrin B
Schisandra chinensis; Schisandrin B; Stress fiber; TGFβ1; Vascular fibrosis; Vascular smooth muscle cell