Ciliary Adenylyl Cyclases control the Hedgehog pathway

Vuolo, Laura; Herrera, Antonio; Torroba, Blanca; Menéndez, Anghara; Pons, Sebastián

doi:10.1242/jcs.172635

Cited by 46 publications

(37 citation statements)

References 40 publications

(30 reference statements)

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“…Adenylyl cyclase 5 and 6 (AC5/6) localize to cilia (23). We performed siRNA knockdown in IMCD3 cells to test whether the tonic cAMP production depends on AC5/6.…”

Section: Resultsmentioning

confidence: 99%

Cilia have high cAMP levels that are inhibited by Sonic Hedgehog-regulated calcium dynamics

Moore

Stepanchick

Tewson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

108

133

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Protein kinase A (PKA) phosphorylates Gli proteins, acting as a negative regulator of the Hedgehog pathway. PKA was recently detected within the cilium, and PKA activity specifically in cilia regulates Gli processing. Using a cilia-targeted genetically encoded sensor, we found significant basal PKA activity. Using another targeted sensor, we measured basal ciliary cAMP that is fivefold higher than whole-cell cAMP. The elevated basal ciliary cAMP level is a result of adenylyl cyclase 5 and 6 activity that depends on ciliary phosphatidylinositol (3,4,5)-trisphosphate (PIP3), not stimulatory G protein (Gαs), signaling. Sonic Hedgehog (SHH) reduces ciliary cAMP levels, inhibits ciliary PKA activity, and increases Gli1. Remarkably, SHH regulation of ciliary cAMP and downstream signals is not dependent on inhibitory G protein (Gαi/o) signaling but rather Ca2+ entry through a Gd3+-sensitive channel. Therefore, PIP3 sustains high basal cAMP that maintains PKA activity in cilia and Gli repression. SHH activates Gli by inhibiting cAMP through a G protein-independent mechanism that requires extracellular Ca2+ entry.

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“…Adenylyl cyclase 5 and 6 (AC5/6) localize to cilia (23). We performed siRNA knockdown in IMCD3 cells to test whether the tonic cAMP production depends on AC5/6.…”

Section: Resultsmentioning

confidence: 99%

Cilia have high cAMP levels that are inhibited by Sonic Hedgehog-regulated calcium dynamics

Moore

Stepanchick

Tewson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

108

133

View full text Add to dashboard Cite

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“…It has been challenging to observe changes in PKA enzymatic activity or cAMP levels in response to Hh ligands, though it is possible that such changes are restricted to a microdomain or to the cilium (41, 42). A direct regulatory role has been suggested based on the observation that GPR161 is cleared from the ciliary membrane in response to SHH or SMO agonists (8, 9).…”

Section: Discussionmentioning

confidence: 99%

G protein–coupled receptors control the sensitivity of cells to the morphogen Sonic Hedgehog

et al. 2018

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The morphogen Sonic Hedgehog (SHH) patterns tissues during development by directing cell fates in a concentration-dependent manner. The SHH signal is transmitted across the membrane of target cells by the heptahelical transmembrane protein Smoothened (SMO), which activates the GLI family of transcription factors through a mechanism that is undefined in vertebrates. Using CRISPR-edited null alleles and small molecule inhibitors, we systematically analyzed the epistatic interactions between SMO and three proteins implicated in SMO signaling: the heterotrimeric G-protein subunit GαS, G protein–coupled receptor kinase 2 (GRK2), and the GαS-coupled receptor GPR161. Our experiments uncovered a signaling mechanism that modifies the sensitivity of target cells to SHH and consequently changes the shape of the SHH dose-response curve. In both fibroblasts and spinal neural progenitors, the loss of GPR161, previously implicated as an inhibitor of basal SHH signaling, increased the sensitivity of target cells across the entire spectrum of SHH concentrations. Surprisingly, GRK2, thought to function by antagonizing GPR161, and Gαs, which is activated by GPR161, influenced SHH signaling even in cells lacking GPR161. We propose that the sensitivity of target cells to Hedgehog (Hh) morphogens, and the consequent effects on gene expression and differentiation outcomes, can be controlled by signals from G-protein coupled receptors that converge on Gαs and Protein Kinase A.

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“…Protein kinase A is activated by cyclic AMP (cAMP), and several adenylyl cyclases that produce cAMP, including AC3, AC5 and AC6, are enriched in cilia (Bishop et al, 2007; Mick et al, 2015; Vuolo et al, 2015). These, in turn, are regulated by G protein coupled receptors (GPCRs), including Gpr161, which activates ACIII and thereby increases cAMP levels (Mukhopadhyay et al 2013).…”

Section: Cilia Are Required For Both Keeping the Pathway Off And Turnmentioning

confidence: 99%

Primary Cilia and Mammalian Hedgehog Signaling

Bangs

Anderson

2016

Cold Spring Harb Perspect Biol

503

489

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It has been a decade since it was discovered that primary cilia have an essential role in Hedgehog signaling in mammals. This discovery came from screens in the mouse that identified a set of genes that are required for both normal Hedgehog signaling and for the formation of primary cilia. Since then, dozens of mouse mutations have been identified that disrupt cilia in a variety of ways and have complex effects on Hedgehog signaling. Here we summarize the genetic and developmental studies used to deduce how Hedgehog signal transduction is linked to cilia and the complex effects that perturbation of cilia structure can have on Hh signaling. We conclude by describing the current status of our understanding of the cell-type specific regulation of ciliogenesis and how that determines the ability of cells to respond to Hedgehog ligands.

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Ciliary Adenylyl Cyclases control the Hedgehog pathway

Cited by 46 publications

References 40 publications

Cilia have high cAMP levels that are inhibited by Sonic Hedgehog-regulated calcium dynamics

Cilia have high cAMP levels that are inhibited by Sonic Hedgehog-regulated calcium dynamics

G protein–coupled receptors control the sensitivity of cells to the morphogen Sonic Hedgehog

Primary Cilia and Mammalian Hedgehog Signaling

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