“21 Jump Street” star Brie Larson has been cast as Joseph Gordon-Levitt’s sister in the “Dark Knight Rises” thesp’s directorial debut “Don Jon’s Addiction.”Gordon-Levitt wrote the script and stars as a porn-addicted, modern day Don Juan who sets out to become a less selfish person after meeting a recently widowed older woman (Julianne Moore). Scarlett Johansson co-stars in the dark comedy alongside Rob Brown and Tony Danza, the latter of whom plays the protag’s father. Ram Bergman (“Looper”) produced the pic with Nicolas Chartier, whose Voltage Pictures financed the film, which is close to wrapping production. Larson will segue from “Don Jon’s Addiction” to James Ponsoldt’s indie “The Spectacular Now,” which stars Shailene Woodley and Miles Teller. Thesp is attached to co-star alongside Olivia Wilde in two upcoming indie comedies — Christopher Storer’s “Relanxious” and Peter Bogdanovich’s “Squirrels to the Nuts.” She’s also expected to return for the “21 Jump Street” sequel. Larson is repped by the Gersh Agency and ROAR.