Publisher Take-Two issued a short statement as part of an SEC filing which read:
We are extremely grateful for his contributions. Rockstar Games has built some of the most critically acclaimed and commercially successful game worlds, a global community of passionate fans and an incredibly talented team, which remains focused on current and future projects.
Houser’s last role with the company was Vice President, Creative at Rockstar. His contributions to some of the biggest video games of the modern era have been immense, serving as lead writer on everything from Grand Theft Auto V to the Red Dead Redemption games.
This is really surprising news, to me at least. When you see people leave companies like BioWare or Blizzard, that's usually because of a merger or acquisition going weird and they no longer feel like they have the power to execute on their game-making desires. I know Rockstar is technically a part of Take Two but I've never heard of any internal friction that would seem to make a move like this likely (although of course Rockstar is pretty buttoned-up for the most part). Here's hoping his departure is just to explore new opportunities (or take a break) rather than something dramatic.