Crosstalk of Hedgehog and mTORC1 Pathways

Area of Science:

• Cell Biology
• Molecular Biology
• Developmental Biology

Background:

• Primary cilia coordinate Hedgehog (Hh) and mTOR signaling pathways, vital for embryonic development and cellular metabolism.
• Crosstalk between Hh and mTOR signaling is observed in cancer cells, suggesting a complex interplay.
• Several studies indicate mechanisms of crosstalk, including TGFβ mediation and regulation of GLI transcription factors.

Purpose of the Study:

• To explore the crosstalk between Hedgehog (Hh) and mTOR signaling pathways.
• To investigate the role of primary cilia in coordinating these signaling networks.
• To synthesize current knowledge and highlight areas of complexity and contradiction in Hh-mTOR interactions.

Main Methods:

• Literature review and synthesis of existing research on Hh and mTOR signaling.
• Analysis of studies investigating crosstalk mechanisms, including molecular regulators and signaling intermediates.
• Examination of observations from cancer cell studies and developmental contexts.

Main Results:

• Increased PI3K/AKT/mTOR activity enhances Hh signaling via GLI factors.
• Hh signaling positively regulates mTORC1 by upregulating NKX2.2, downregulating mTOR inhibitors.
• Kinases like DYRK2, DYRK1A, and DYRK1B show varied regulatory roles in both Hh and mTORC1 pathways, highlighting pathway complexity.

Conclusions:

• The interaction between Hh and mTORC1 signaling is likely more widespread than currently recognized.
• Contradictory findings and the involvement of multiple partners indicate that the Hh-mTORC1 interplay is not fully elucidated.
• Further research is needed to resolve discrepancies and fully understand the complex crosstalk between these essential signaling pathways.