Optogenetic activation of intracellular antibodies for direct modulation of endogenous proteins

Abstract

Intracellular antibodies, such as nanobodies and single-chain variable fragments (scFv), have become powerful tools for imaging, modulating, and neutralizing endogenous target proteins. Although a variety of antibody engineering techniques have been developed, an optogenetic tool for activating intracellular antibody to precisely control its target protein has not been reported. In chapter 1, I describe an optogenetically activatable intracellular antibody (Optobody) consisting of split antibody fragments and blue light-mediated heterodimerization domains. Blue light stimulation activates the optobody, inducing it to capture its target protein and subsequently inhibit the target. In chapter 2, I expanded this optobody platform by generating various optobodies from previously developed intracellular antibodies. In chapter 3, I demonstrated that photoactivation of a gelsolin (GSN) optobody and $\beta$2 adrenergic receptor ($\beta$2AR) optobody shut down endogenous GSN activity and $\beta$2AR signaling, respectively. Applying the novel optogenetic platform to the broad pool of available intracellular antibodies will facilitate optogenetic manipulation of various endogenous proteins and may provide a basis for designing potential inducible drugs.