The fall from grace of a rising star in China’s Communist Party sheds light on how a reshuffle of the country’s top officials may play out under the leadership of President Xi Jinping later this year.

Sun Zhengcai, 53, the youngest member of the ruling Politburo, was replaced Saturday as party chief of the southwestern metropolis of Chongqing. He is under investigation for violating party regulations, according to four officials with knowledge of the matter.