engleski

Localization and interaction dynamics of Gli1, SuFu and GSK3beta in HEK293 cells

The Hedgehog-Gli (Hh-Gli) signalling pathway plays a crucial role in embryonic development, but is mainly inactive in adult tissues. Impaired signalling during development can lead to various developmental malformations. Aberrant activation of this pathway in adult tissues has been implicated in the development of cancers in various organs. Although the basics of the signalling pathway are well known there are mechanisms regulating the pathway that are not fully understood yet. For example, the interactions between the transcription factor Gli1 and its regulators Suppressor of Fused (SuFu) and GSK3. The mechanism controlling the association of the SuFu/Gli1 complex to microtubules, the role of GSK3 in activated cells or the transport dynamics of these proteins in and out of the primary cilium. To fully understand the functioning of this pathway, it is essential to establish the localization and interaction dynamics between its components. We used human embryonic kidney cells (HEK293) as a model, since they have adequate expression of pathway genes. Our results revealed an interesting pattern. Gli1, SuFu and their regulator GSK3 co-localized in highly specific cytoplasmic spots of positive staining. These spots also stained positively for -tubulin, a centrosomal marker, suggesting that these proteins accumulate in the centrosome, which gives rise to basal bodies of the primary cilia. In our hands the primary cilia were undetectable under tested conditions. After adding exogenous Shh protein the accumulation of these proteins in the centrosomes decreased and translocation of Gli1 to the nucleus was observed. On the other hand, Ptch and Shh also co-localized in the cytoplasm but not in the centrosome. Gli3, the transcription repressor, showed cytoplasmic localization as well, in the region similar to that of Ptch and Shh. We have shown an interesting pattern of interactions between the effector of the Hh-Gli signalling pathway, Gli1, and its regulators, SuFu and GSK3, positioning them all in the same organelle, the centrosome, demonstrating that even without primary cilia these proteins accumulate in specific regions, centrosomes, suggesting that that is where the regulatory processes between them take place.

Hh-Gli signaling pathway; Gli1; SuFu; GSK3beta

nije evidentirano