“Mary Tyler Moore could light up a room! She is an icon and a friend,” the statement reads. “She was my cast mate and my boss. She was incredibly funny and completely generous.”
Keaton, 65, 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.
“As an actor and comedian, she allowed me and everyone to perform,” Keaton continues. “Letting us just do our thing without any competitiveness. 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.”
The Oscar-nominee took to Twitter after he heard news of her death, writing, “Mary(MTM) was a gem. She was iconic, my boss, cast mate and a friend and I will miss her.”
Moore died on Wednesday at the age of 80. According to a source, Moore had been on a ventilator and had been hospitalized with pneumonia due to complications from her diabetes.
Her longtime rep issued a statement to PEOPLE: “Today, beloved icon, Mary Tyler Moore, passed away at the age of 80 in the company of friends and her loving husband of over 33 years, Dr. S. Robert Levine. A groundbreaking actress, producer, and passionate advocate for the Juvenile Diabetes Research Foundation, Mary will be remembered as a fearless visionary who turned the world on with her smile.”
Moore suffered from a variety of health problems and was a Type 1 diabetic. In May 2011, she underwent elective surgery to remove a benign tumor of the lining tissue of the brain.
Moore was diagnosed with diabetes at 33. “I thought I’d have to recline on a chaise the rest of my life,” she told PEOPLE in 2009. After that, she said, “there have been challenges, but I’ve triumphed.”