Your status doesn't matter if your I-485 is submitted. You are still J1 status before I-485 application is approved. I-485 application is a petition of adjustment of status (AOS). If the application is not approved, your status is not adjusted and keeps previous status, J1, H1 or whatever else. If the application is approved, you status becomes GC holder.
From another viewpoint, you have to maintain a valid status before I-485 is approved.