The Patched dependence receptor triggers apoptosis through a DRAL-caspase-9 complex

Nat Cell Biol. 2009 Jun;11(6):739-46. doi: 10.1038/ncb1880. Epub 2009 May 24.


Sonic hedgehog (Shh) and its main receptor, Patched (Ptc), are implicated in both neural development and tumorigenesis. Besides its classic morphogenic activity, Shh is also a survival factor. Along this line, Ptc has been shown to function as a dependence receptor; it induces apoptosis in the absence of Shh, whereas its pro-apoptotic activity is blocked in the presence of Shh. Here we show that, in the absence of its ligand, Ptc interacts with the adaptor protein DRAL (downregulated in rhabdomyosarcoma LIM-domain protein; also known as FHL2). DRAL is required for the pro-apoptotic activity of Ptc both in immortalized cells and during neural tube development in chick embryos. We demonstrate that, in the absence of Shh, Ptc recruits a protein complex that includes DRAL, one of the caspase recruitment (CARD)-domain containing proteins TUCAN (family member, 8) or NALP1 (NLR family, pyrin domain containing 1) and apical caspase-9. Ptc triggers caspase-9 activation and enhances cell death through a caspase-9-dependent mechanism. Thus, we propose that in the absence of its ligand Shh the dependence receptor Ptc serves as the anchor for a caspase-activating complex that includes DRAL, and caspase-9.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • CARD Signaling Adaptor Proteins / genetics
  • CARD Signaling Adaptor Proteins / metabolism
  • Caspase 9 / metabolism*
  • Cell Line
  • Chick Embryo
  • Hedgehog Proteins / genetics
  • Hedgehog Proteins / metabolism*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • LIM-Homeodomain Proteins
  • Multiprotein Complexes / metabolism
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism
  • Patched Receptors
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction / physiology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Two-Hybrid System Techniques


  • Adaptor Proteins, Signal Transducing
  • Apoptosis Regulatory Proteins
  • CARD Signaling Adaptor Proteins
  • CARD8 protein, human
  • FHL2 protein, human
  • Hedgehog Proteins
  • Homeodomain Proteins
  • LIM-Homeodomain Proteins
  • Multiprotein Complexes
  • Muscle Proteins
  • NLRP1 protein, human
  • Neoplasm Proteins
  • Patched Receptors
  • RNA, Small Interfering
  • Receptors, Cell Surface
  • SHH protein, human
  • Transcription Factors
  • Caspase 9