Lynne Koplin, chief merchandising officer of True Religion Apparel Inc., has resigned from the firm after a nearly four-year tenure.

Koplin, who joined True Religion in 2010 after serving as president of Tommy Bahama’s women’s division at Oxford Industries Inc., is said to be leaving for personal reasons. The company confirmed her exit but declined to comment on the reasons behind it or plans to fill the post.

Gary Harvey and Rosella Giuliani, creative director and senior vice president of merchandising, respectively, at the Vernon, Calif.-based premium denim firm, previously reported to Koplin and now will report to David Conn, chief executive officer.

Koplin changed jobs on a regular basis during her four years at the company, joining as chief operating officer in 2010 and in 2011 succeeding Michael Egeck as president when he left the firm to become ceo of Nike’s Hurley brand.

She became interim ceo last March when Jeffrey Lubell, who founded the company in March 2002, stepped down as chairman, ceo and creative director in the midst of the company’s investigation of strategic alternatives and after the company’s board said it wouldn’t renew his employment contract when it expired three months later.

True Religion’s exploration of its options ultimately led to the company’s acquisition by TowerBrook Capital Partners LP for $835 million in July, at which time Koplin was appointed to her most recent post and Conn was brought in as ceo.

Koplin began her career in retail and held merchandising posts at I. Magnin, Marshall Field & Co. and Burdines before moving into wholesale, where she distinguished herself at first as a swimwear expert, working at Warnaco Group Inc.’s Anne Cole unit and later as president of Apparel Ventures Inc., which held the license for Tommy Bahama swimwear.

True Religion’s executive ranks also include Eric Bauer, chief operating officer and chief financial officer, and Mary Alderete, who joined the company from Levi Strauss & Co. last month as chief marketing officer.