By Oliver Gettell
January 25, 2017 at 05:51 PM EST
Andy Kropa/Getty Images; Elisabetta A. Villa/Getty Images

Michael Keaton has shared a heartfelt tribute to Mary Tyler Moore, the late TV icon who helped foster his early show biz career in the 1970s.

Responding to the news that Moore died Wednesday at age 80, Keaton wrote on Twitter, “Mary(MTM) was a gem. She was iconic, my boss, cast mate and a friend and I will miss her.”

In a subsequent statement provided to EW, Keaton said, “Mary Tyler Moore could light up a room! She is an icon and a friend. She was my cast mate and my boss. She was incredibly funny and completely generous. As an actor and comedian, she allowed me and everyone to perform — letting us just do our thing without any competiveness.”

He continued, “She was not only a pioneer in TV, comedy and business but she was a role model for women in general. She built an empire with MTM Enterprises and she paved the way for our new talents like Amy, Tina and others. She is truly going to be missed.”

Years before he starred in such films as Beetlejuice and Batman, Keaton worked with Moore as a cast member on two CBS variety shows: Mary, which ran for three episodes in 1978, and The Mary Tyler Moore Hour, which ran for 11 episodes the following year.

During an appearance on the Late Show in 2015, Keaton and fellow Mary alum David Letterman humorously recalled how much they dreaded learning their dance routines.

“Every Wednesday the choreographer would come in and teach us — Michael and myself and the rest of the cast — how to dance and the [do] big number,” Letterman said. “It was the worst day of my life for an entire summer.”

Keaton added, “It was unbelievably uncomfortable, was it not?”

Watch a clip of Keaton and Letterman on Mary above, and read more stars’ reactions to Moore’s death here.