Genetic Analysis Reveals a Hierarchy of Interactions between Polycystin-Encoding Genes and Genes Controlling Cilia Function during Left-Right Determination.
During mammalian development, left-right (L-R) asymmetry is established by a cilia-driven leftward fluid flow within a midline embryonic cavity called the node. This 'nodal flow' is detected by peripherally-located crown cells that each assemble a primary cilium which contain the putative Ca2+ channel PKD2. The interaction of flow and crown cell cilia promotes left side-specific expression of Nodal in the lateral plate mesoderm (LPM). Whilst the PKD2-interacting protein PKD1L1 has also been implicated in L-R patterning, the underlying mechanism by which flow is detected and the genetic relationship between Polycystin function and asymmetric gene expression remains unknown. Here, we characterize a Pkd1l1 mutant line in which Nodal is activated bilaterally, suggesting that PKD1L1 is not required for LPM Nodal pathway activation per se, but rather to restrict Nodal to the left side downstream of nodal flow. Epistasis analysis shows that Pkd1l1 acts as an upstream genetic repressor of Pkd2. This study therefore provides a genetic pathway for the early stages of L-R determination. Moreover, using a system in which cultured cells are supplied artificial flow, we demonstrate that PKD1L1 is sufficient to mediate a Ca2+ signaling response after flow stimulation. Finally, we show that an extracellular PKD domain within PKD1L1 is crucial for PKD1L1 function; as such, destabilizing the domain causes L-R defects in the mouse. Our demonstration that PKD1L1 protein can mediate a response to flow coheres with a mechanosensation model of flow sensation in which the force of fluid flow drives asymmetric gene expression in the embryo.
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Daniel T
DT
Grimes
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Jennifer L
JL
Keynton
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.|School of Biological Sciences, University of Reading, Whiteknights, Reading, United Kingdom.|Diamond Light Source, Beamline B23, Chilton, Didcot, United Kingdom.
Maria T
MT
Buenavista
Chapman University and the University of California, Irvine, Irvine, California, United States of America.
Xingjian
X
Jin
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Saloni H
SH
Patel
Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University and CREST, Japan Science and Technology Corporation (JST), Suita, Japan.
Shinohara
S
Kyosuke
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Jennifer
0000-0003-3841-2222
J
Vibert
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Debbie J
DJ
Williams
Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University and CREST, Japan Science and Technology Corporation (JST), Suita, Japan.
Hiroshi
H
Hamada
Diamond Light Source, Beamline B23, Chilton, Didcot, United Kingdom.
Rohanah
R
Hussain
Chapman University and the University of California, Irvine, Irvine, California, United States of America.
Surya M
SM
Nauli
MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom.
Dominic P
DP
Norris
D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002923:Cilia / Q000235:genetics*; D004622:Embryo, Mammalian / Q000166:cytology; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics*; D008648:Mesoderm / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D008822:Mice, Transgenic; D055457:Nodal Protein / Q000096:biosynthesis / Q000235:genetics*; D017434:Protein Structure, Tertiary; D050396:TRPP Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics*
D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D055457:Nodal Protein; D050396:TRPP Cation Channels; C119003:Dte protein, mouse; C526008:Nodal protein, mouse; C486742:Pkd1l1 protein, mouse