In this talk, I'll give a brief summary of how one-loop
renormalize both bulk and brane eﬀective interactions for geometries sourced by codimension-two
branes. I'll then discuss what these results imply for a six-dimensional
supergravity model which aims to capture the features that make extra-dimensional
physics attractive for understanding naturalness issues in particle physics.
I'll also emphasize the role that brane back-reaction plays in yielding
unexpected results, and present a one-loop contribution to the 4D vacuum energy
whose size is set by the KK scale.