An administrator can subscribe users or groups to a topic. In this case the topic will be added to the users MyTopic page.
In addition administrators can grant user permissions for a topic:
Read: users can read the content of an article but can't add annotation or copy/create content into the topic
Publish: user has the permission to add annotation for an article , copy article into the topic, post manual content into the topic, e-mail content into the topic.
Manage: user has administrative rights for the topic.
For details watch this video clip.