Kulkarni SS and Khokha MK (2018), WDR5 regulates left-right patterning via chroma...

XB-ART-55418

Development January 1, 2018; 145 (23):

WDR5 regulates left-right patterning via chromatin-dependent and -independent functions.

Kulkarni SS , Khokha MK .

Abstract
Congenital heart disease (CHD) is a major cause of infant mortality and morbidity, yet the genetic causes and mechanisms remain opaque. In a patient with CHD and heterotaxy, a disorder of left-right (LR) patterning, a de novo mutation was identified in the chromatin modifier gene WDR5 WDR5 acts as a scaffolding protein in the H3K4 methyltransferase complex, but a role in LR patterning is unknown. Here, we show that Wdr5 depletion leads to LR patterning defects in Xenopus via its role in ciliogenesis. Unexpectedly, we find a dual role for WDR5 in LR patterning. First, WDR5 is expressed in the nuclei of monociliated cells of the LR organizer (LRO) and regulates foxj1 expression. LR defects in wdr5 morphants can be partially rescued with the addition of foxj1 Second, WDR5 localizes to the bases of cilia. Using a mutant form of WDR5, we demonstrate that WDR5 also has an H3K4-independent role in LR patterning. Guided by the patient phenotype, we identify multiple roles for WDR5 in LR patterning, providing plausible mechanisms for its role in ciliopathies like heterotaxy and CHD.

PubMed ID: 30377171
PMC ID: PMC6288385
Article link: Development
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: arl13b dand5 dkk1 dnah9 foxj1 foxj1.2 lefty myf5 nodal1 nodal3.1 otx2 pitx2 rfx2 shh sox2 tuba4b tubg1 wdr5 wnt8a
GO keywords: heart development [+]
Antibodies: Arl13b Ab3 Tuba4b Ab5 Tubg1 Ab4 wdr5 Ab1
Morpholinos: wdr5 MO4 wdr5 MO5

Disease Ontology terms: visceral heterotaxy [+]
OMIMs: HETEROTAXY, VISCERAL, 1, X-LINKED; HTX1

Article Images: [+] show captions

	Figure 1: Wdr5 depletion alters left-right patterning in Xenopus tropicalis. (a, b) Percentage of embryos that have abnormal (a) pitx2 or (b) dand5 expression. Embryos were injected at the one-cell stage or in one cell at the two-cell stage with wdr5 MO. L, left; R, right; Bilateral: signal present on both sides; Absent, signal absent on both sides; Reduced: signal reduced on both sides. (c, d, e, f, g) Percentage of embryos that have abnormal pitx2 expression. Embryos were injected at the one-cell stage with (c) scrambled MO, (d) wdr5 MO, wdr5 MO + human WDR5-3xGFP, scrambled MO injected on the right or left side of embryos, (e) Second wdr5 MO, (f) wdr5 MO, wdr5 MO + K7Q-WDR5-3XGFP, or K7Q-WDR5-3XGFP, or (g) wdr5 MO and wdr5 MO + human 26-334-3xGFP. Experiments were repeated 3 times. ‘n’ = number of embryos. ★, ★★ and ★★★ indicate P < 0.05, P <0.005 and P <0.0005.
	Figure 2: Wdr5 depletion affects cilia morphology in the LRO of Xenopus tropicalis. (a) Cilia in control and wdr5 morphant Xenopus LROs marked by anti-acetylated α-tubulin (green) and F-actin marked by phalloidin (red). (b, c) Number of cilia normalized to the LRO area (b) and length of cilia (c) between uninjected controls and wdr5 morphants. Data is presented as box plot with 95% confidence interval. ‘n’ = number of embryos. (d) Number of cilia posteriorly localized in the LRO cells in uninjected controls and wdr5 morphants. Experiments were repeated 2 times. ★ and ★★★ indicate P <0.05 and P <0.0005.
	Figure 3: WDR5 has chromatin dependent and independent roles in ciliogenesis in the LRO (a) In situ hybridization for foxj1 in the Xenopus LRO in uninjected controls and wdr5 morphants at stage 16. Embryos were bisected to reveal expression of foxj1 in the entire GRP (left panels, dorsal to top and ventral view so right margin of LRO is to the left. Margin of GRPs marked by white lines). GRPs were again bisected within the LRO (dashed white line) to reveal foxj1 expression within the tissue (right panels, dorsal to the top and arrows mark the ventral surface indicated by dashed white box at the bottom where the LRO resides and showing loss of foxj1 in the ventral tissue). D, dorsal, V, ventral. (b) Percentage of embryos that have abnormal foxj1 expression in control and wdr5 morphant Xenopus LROs.
	Figure 4: Domain analysis of WDR5 Localization of different deletion constructs for WDR5-3xGFP at the ciliary base and nuclei of the Xenopus LRO. LUT used for WDR5-3xGFP is green, and for Arl13b-Cherry, LUT is Hot Magenta.
	Figure S1: Early markers of LR patterning in Xenopus. (a) In situ hybridization for coco in the Xenopus LRO showing normal and abnormal expression patterns. Images are ventral views with anterior to the top. (b) In situ hybridization for pitx2 in Xenopus lateral plate mesoderm showing normal and abnormal expression pattern. Lateral views with dorsal to the top. Embryo sides are indicated above figure.
	Figure S2: Wdr5 depletion leads to defective cilia in the LRO. Scanning electron microscope (SEM) images showing cilia morphology (red arrows) in the LRO of uninjected controls and wdr5 morphants.
	Figure S3: Early markers of dorso-ventral development and cilia cell fate. (a) In situ hybridization for early developmental markers at stage 10-11 Xenopus embryos in uninjected controls (top row) and wdr5 morphants (bottom row). All vegetal views with dorsal to the left (at stage 10-11). (b) In situ hybridization for sox2 at stage 14, with an anterior view with dorsal to the top. (c) In situ hybridization for dand5 and xnr1 in the Xenopus LRO at stage 16. Margin of the LRO is indicated by dashed white lines. (d) In situ hybridization for shh and lefty at stage 16, with an anterior view with dorsal to the top. (e) In situ hybridization for rfx2 and dnah9 in the Xenopus LRO at stage 16. Margin of the LRO is indicated by dashed white lines. (f) Quantification of in situ hybridization for the midline marker dand5, xnr1, shh, lefty, rfx2 and dnah9. Abnormal is either reduced or absent expression compared to wildtype expression (normal). Experiments were repeated 2-3 times. ‘n’ = number of embryos.
	Figure S4: WDR5 is specifically localized to the base of cilia Immunofluorescence showing localization of WDR5 (green) and γ tubulin (magenta) in monociliated human RPE cell. WDR5 signal is lost after incubating the antibody with the blocking peptide. Box region shows the base of cilia where WDR5 is localized in control but not in the blocking control. Experiment was repeated 2 times.

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