Persistent mechanical stretch-induced calcium overload and MAPK signal activation contributed to SCF reduction in colonic smooth muscle in vivo and in vitro

Abstract

Gastrointestinal (GI) distention is a common pathological characteristic in most GI motility disorders (GMDs), however, their detail mechanism remains unknown. In this study, we focused on Ca²⁺ overload of smooth muscle, which is an early intracellular reaction to stretch, and its downstream MAPK signaling and also reduction of SCF in vivo and in vitro. We successfully established colonic dilation mouse model by keeping incomplete colon obstruction for 8 days. The results showed that persistent colonic dilation clearly induced Ca²⁺ overload and activated all the three MAPK family members including JNK, ERK and p38 in smooth muscle tissues. Similar results were obtained from dilated colon of patients with Hirschsprung's disease and stretched primary mouse colonic smooth muscle cells (SMCs). Furthermore, we demonstrated that persistent stretch-induced Ca²⁺ overload was originated from extracellular Ca²⁺ influx and endoplasmic reticulum (ER) Ca²⁺ release identified by treating with different Ca²⁺ channel blockers, and was responsible for the persistent activation of MAPK signaling and SCF reduction in colonic SMCs. Our results suggested that Ca²⁺ overload caused by smooth muscle stretch led to persistent activation of MAPK signaling which might contribute to the decrease of SCF and development of the GMDs.

Keywords:

• Calcium overload
• colonic smooth muscle
• gastrointestinal motility disorder
• interstitial cell of Cajal
• MAPK signaling

Acknowledgements

We greatly appreciate Prof. Jie Du in Beijing Institute of Heart, Lung and Blood Vessel Diseases, Anzhen Hospital Affiliated the Capital Medical University for his kind support in the application of Flexcell system.

Disclosure statement

The authors declare no conflict of interest.

Funding

This study was supported by the National Science Foundation of China (81300285, 81572322 and 31371220), the Specialized Research Fund for the Doctoral Program of Higher Education of China (20121107120020), the Scientific Research Key Program of Beijing Municipal Commission of Education (KZ201310025020) and the Beijing Natural Science Foundation (7152023).