RT Journal Article SR Electronic T1 mTORC1 hampers Hedgehog signaling in Tsc2 deficient cells JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202302419 DO 10.26508/lsa.202302419 VO 7 IS 11 A1 Larsen, Lasse Jonsgaard A1 Østergaard, Elsebet A1 Møller, Lisbeth Birk YR 2024 UL https://www.life-science-alliance.org/content/7/11/e202302419.abstract AB The mTORC1-complex is negatively regulated by TSC1 and TSC2. Activation of Hedgehog signaling is strictly dependent on communication between Smoothened and the Hedgehog-signaling effector and transcription factor, GLI2, in the primary cilium. Details about this communication are not known, and we wanted to explore this further. Here we report that in Tsc2−/− MEFs constitutively activated mTORC1 led to mis-localization of Smoothened to the plasma membrane, combined with increased concentration of GLI2 in the cilia and reduced Hedgehog signaling, measured by reduced expression of the Hedgehog target gene, Gli1. Inhibition of mTORC1 rescued the cellular localization of Smoothened to the cilia, reduced the cilia concentration of GLI2, and restored Hedgehog signaling. Our results reveal evidence for a two-step activation process of GLI2. The first step includes GLI2 stabilization and cilium localization, whereas the second step includes communication with cilia-localized Smoothened. We found that mTORC1 inhibits the second step. This is the first demonstration that mTORC1 is involved in the regulation of Hedgehog signaling.All relevant data of this study are available within the article and its Supplementary Information files or from corresponding author on request.