Holt has been linked with Celtic this season.
Hughton said: "All I've seen is some press speculation. What we have in Grant is someone who has signed a contract in the summer.
"He has two years left of his contract. I think he started more games than he did last season so this is somebody who is right in there playing games.
"Anything that is heard or written about is very much speculation. For me it has not been an issue."