A board member at Los Angeles’s Museum of Contemporary Art has resigned and four “life trustees” published a letter of protest over the institution’s direction in continuing fallout over the firing last month of its longtime chief curator, writes the Los Angeles Times.

Artist John Baldessari said the ouster of curator Paul Schimmel and this week’s announcement that the museum would mount a show on the cultural influence of disco prompted his departure after 12 years on the board. The museum has incorporated more pop culture into its offerings under Jeffrey Deitch, the former art dealer hired as its director in 2010.

Four other board members have stepped down since February, with one citing other concerns about Mr. Deitch and the museum’s governance.

On Thursday the newspaper published a letter from four life trustees—an honorific bestowed on longtime supporters—that questioned its “celebrity-driven program” and called for a return to exhibitions steeped in art history. The writers were responding to a Sunday Times column defending Mr. Deitch’s leadership by billionaire philanthropist Eli Broad, another life trustee and the museum’s biggest financial backer.