中ちゅう心しんとなる

expression, godan verb (-ru)

play a central role; take a leading part

Used when someone or something is at the core of an activity, project, or group, often implying active leadership or being the main figure.

• 彼かの女じょはプロジェクトで中ちゅう心しんとなって活かつ躍やくした。

  She played a central role in the project.

• この会かい議ぎでは、環かん境きょう問もん題だいが中ちゅう心しんとなるだろう。

  Environmental issues will likely take center stage at this conference.