I just had this same problem and fixed it.
If you have a "Missing server side dependencies" error in your Central Administration health analyzer then you first need to follow these instructions
(I know this looks like it's not related but I promise you, it is!)
Credit goes to John D. Palm for the first part of the solution to this problem.
the second thing you need to do, now that the timer service is running is you need to sync the profiles, or you can just wait an hour and they will sync by themselves. I like to do things by hand so I know I have the right answer. The way you do that is go into Central Administration > Monitoring > Job Definitions and then go down to these two jobs and run them now and in this order:
User Profile Service Application - User Profile Change Job
User Profile Service Application - User Profile to SharePoint Full Synchronization
Once you do that, reload your discussion threads in list view and you will see the profile pictures showing up. Let your people know that these pictures won't update on the fly. If they change their profile picture, the old picture will still show in the discussion thread until The sync job runs. By default the User profile change job is set to run hourly.