Why would MP fold an jack or queen when you limped preflop and are betting here? unless you are the tightest player on earth i'm not automatically putting you on an ace here, that's silly. preflop you likely have the best hand, on the flop you have high pair and a gutshot to the nut straight, on the turn you have high trips, still a straight draw, and now have a draw to aces full if someone (unlikely) has the straight or hits their flush.

3 bet the turn, call down U/I if capped.