Philip Beachy, PhD

My lab studies the function of Hedgehog proteins and other extracellular signals in morphogenesis (pattern formation) and in injury repair and regeneration (pattern maintenance). We study how the distribution of such signals is regulated in tissues, how cells perceive and respond to distinct concentrations of signals, and how such signaling pathways arose in evolution. We also study the normal roles of such signals in stem-cell physiology and their abnormal roles in the formation and expansion of cancer stem cells.

The Ernest and Amelia Gallo Professor, Professor of Urology, of Developmental Biology and, by courtesy, of Chemical and Systems Biology

Publications

  • Dispatched uses Na+ flux to power release of lipid-modified Hedgehog. Nature Wang, Q., Asarnow, D. E., Ding, K., Mann, R. K., Hatakeyama, J., Zhang, Y., Ma, Y., Cheng, Y., Beachy, P. A. 2021

    Abstract

    The Dispatched protein, which is related to the NPC1 and PTCH1 cholesterol transporters1,2 and to H+-driven transporters of the RND family3,4, enables tissue-patterning activity of the lipid-modified Hedgehog protein by releasing it from tightly-localized sites of embryonic expression5-10. Here we determine a cryo-electron microscopy structure of the mouse protein Dispatched homologue 1 (DISP1), revealing three Na+ ions coordinated within a channel that traverses its transmembrane domain. We find that the rate of Hedgehog export is dependent on the Na+ gradient across the plasma membrane. The transmembrane channel and Na+ binding are disrupted in DISP1-NNN, a variant with asparagine substitutions for three intramembrane aspartateresidues that each coordinate and neutralize the charge of one of the three Na+ ions. DISP1-NNN and variants that disrupt single Na+ sites retain binding to, but are impaired in export of the lipid-modified Hedgehog protein to the SCUBE2 acceptor. Interaction of the amino-terminalsignallingdomain of theSonic hedgehog protein(ShhN) with DISP1 occurs via an extensive buried surface area and contacts with an extended furin-cleaved DISP1 arm. Variability analysis reveals that ShhN binding is restricted to one extreme of a continuous series of DISP1 conformations. The bound and unbound DISP1 conformations display distinct Na+-site occupancies, which suggests a mechanism by which transmembrane Na+ flux may power extraction of the lipid-linked Hedgehog signal from the membrane. Na+-coordinating residues in DISP1 are conserved in PTCH1 and other metazoan RND family members, suggesting that Na+ flux powers their conformationally driven activities.

    View details for DOI 10.1038/s41586-021-03996-0

    View details for PubMedID 34707294

  • Hedgehog pathway activation through nanobody-mediated conformational blockade of the Patched sterol conduit. Proceedings of the National Academy of Sciences of the United States of America Zhang, Y., Lu, W., Bulkley, D. P., Liang, J., Ralko, A., Han, S., Roberts, K. J., Li, A., Cho, W., Cheng, Y., Manglik, A., Beachy, P. A. 2020

    Abstract

    Activation of the Hedgehog pathway may have therapeutic value for improved bone healing, taste receptor cell regeneration, and alleviation of colitis or other conditions. Systemic pathway activation, however, may be detrimental, and agents amenable to tissue targeting for therapeutic application have been lacking. We have developed an agonist, a conformation-specific nanobody against the Hedgehog receptor Patched1 (PTCH1). This nanobody potently activates the Hedgehog pathway in vitro and in vivo by stabilizing an alternative conformation of a Patched1 "switch helix," as revealed by our cryogenic electron microscopy structure. Nanobody-binding likely traps Patched in one stage of its transport cycle, thus preventing substrate movement through the Patched1 sterol conduit. Unlike the native Hedgehog ligand, this nanobody does not require lipid modifications for its activity, facilitating mechanistic studies of Hedgehog pathway activation and the engineering of pathway activating agents for therapeutic use. Our conformation-selective nanobody approach may be generally applicable to the study of other PTCH1 homologs.

    View details for DOI 10.1073/pnas.2011560117

    View details for PubMedID 33139559

  • Smoothened stimulation by membrane sterols drives Hedgehog pathway activity. Nature Deshpande, I., Liang, J., Hedeen, D., Roberts, K. J., Zhang, Y., Ha, B., Latorraca, N. R., Faust, B., Dror, R. O., Beachy, P. A., Myers, B. R., Manglik, A. 2019

    Abstract

    Hedgehog signalling is fundamental to embryonic development and postnatal tissue regeneration1. Aberrant postnatal Hedgehog signalling leads to several malignancies, including basal cell carcinoma and paediatric medulloblastoma2. Hedgehog proteins bind to and inhibit the transmembrane cholesterol transporter Patched-1 (PTCH1), which permits activation of the seven-transmembrane transducer Smoothened (SMO) via a mechanism that is poorly understood. Here we report the crystal structure of active mouse SMO bound to both the agonist SAG21k and to an intracellular binding nanobody that stabilizes a physiologically relevant active state. Analogous to other G protein-coupled receptors, the activation of SMO is associated with subtle motions in the extracellular domain, and larger intracellular changes. In contrast to recent models3-5, a cholesterol molecule that is critical for SMO activation is bound deep within the seven-transmembrane pocket. We propose that the inactivation of PTCH1 by Hedgehog allows a transmembrane sterol to access this seven-transmembrane site (potentially through a hydrophobic tunnel), which drives the activation of SMO. These results-combined with signalling studies and molecular dynamics simulations-delineate the structural basis for PTCH1-SMO regulation, and suggest a strategy for overcoming clinical resistance to SMO inhibitors.

    View details for DOI 10.1038/s41586-019-1355-4

    View details for PubMedID 31263273

  • Structural Basis for Cholesterol Transport-like Activity of the Hedgehog Receptor Patched. Cell Zhang, Y., Bulkley, D. P., Xin, Y., Roberts, K. J., Asarnow, D. E., Sharma, A., Myers, B. R., Cho, W., Cheng, Y., Beachy, P. A. 2018

    Abstract

    Hedgehog protein signals mediate tissue patterning and maintenance by binding to and inactivating their common receptor Patched, a 12-transmembrane protein that otherwise would suppress the activity of the 7-transmembrane protein Smoothened. Loss of Patched function, the most common cause of basal cell carcinoma, permits unregulated activation of Smoothened and of the Hedgehog pathway. A cryo-EM structure of the Patched protein reveals striking transmembrane domain similarities to prokaryotic RND transporters. A central hydrophobic conduit with cholesterol-like contents courses through the extracellular domain and resembles that used by other RND proteins to transport substrates, suggesting Patched activity in cholesterol transport. Cholesterol activity in the inner leaflet of the plasma membrane is reduced by PTCH1 expression but rapidly restored by Hedgehog stimulation, suggesting that PTCH1 regulates Smoothened by controlling cholesterol availability.

    View details for PubMedID 30415841

  • Cilia-Associated Oxysterols Activate Smoothened. Molecular cell Raleigh, D. R., Sever, N., Choksi, P. K., Sigg, M. A., Hines, K. M., Thompson, B. M., Elnatan, D., Jaishankar, P., Bisignano, P., Garcia-Gonzalo, F. R., Krup, A. L., Eberl, M., Byrne, E. F., Siebold, C., Wong, S. Y., Renslo, A. R., Grabe, M., McDonald, J. G., Xu, L., Beachy, P. A., Reiter, J. F. 2018; 72 (2): 316

    Abstract

    Primary cilia are required for Smoothened to transduce vertebrate Hedgehog signals, but how Smoothened accumulates in cilia and is activated is incompletely understood. Here, we identify cilia-associated oxysterols that promote Smoothened accumulation in cilia and activate the Hedgehog pathway. Our data reveal that cilia-associated oxysterols bind to two distinct Smoothened domains to modulate Smoothened accumulation in cilia and tune the intensity of Hedgehog pathway activation. We find that the oxysterol synthase HSD11beta2 participates in the production of Smoothened-activating oxysterols and promotes Hedgehog pathway activity. Inhibiting oxysterol biosynthesis impedes oncogenic Hedgehog pathway activation and attenuates the growth of Hedgehog pathway-associated medulloblastoma, suggesting that targeted inhibition of Smoothened-activating oxysterol production may be therapeutically useful for patients with Hedgehog-associated cancers.

    View details for PubMedID 30340023