In:
The FASEB Journal, Wiley, Vol. 30, No. S1 ( 2016-04)
Abstract:
Hemodynamic forces are intimately linked with cardiac morphogenesis. Trabeculation develops after cardiac looping, and mutations in Notch signaling result in congenital heart defects. The mechanotransduction mechanisms underlying trabeculation remain elusive. We assessed whether shear stress up‐regulated Notch signaling to modulate trabeculation with implications for contractile function. We implemented the light‐sheet method Selective Plane Illumination Microscopy (SPIM) for fast imaging and high axial resolution of myocardium (3‐D+time) in live zebrafish embryos. 3‐D quantification revealed attenuation in trabeculated myocardium in response to reduced viscosity and shear stress by Gata1a ‐morpholino oligonucleotides (MO) micro‐injection and in the absence of atrial contractions in wea mutants. However, co‐injection with Nrg‐1 mRNA rescued trabeculation and restored mRNA expression of Notch ligands (Dll4, Jagged‐1 and Jagged‐2), receptor (Notch 1b), and signaling components (Nrg‐1 and ErbB2). Trabeculation was inhibited in response to 1) arresting hemodynamic forces by blocking cardiac Troponin T type 2a via Tnnt2a ‐MO, and 2) depleting endocardium via the use of the cloche mutant. Tnnt2a ‐MO down‐regulated Notch target genes to a greater extent than did Gata1a ‐MO and exhibited a thin ventricular wall without trabeculation, and cloche mutant expressed low levels of Notch‐related genes. A pulsatile flow system (t average =23 dyn·cm −2 at 1 Hz) corroborated shear stress activation of Notch target genes. Gata1a MO and the ErbB2 inhibitor AG1478 further reduced ventricular strain and fractional shortening, coupled with increased systolic and diastolic volume. Gata1a MO micro‐injection and wea mutant resulted in an attenuation of trabecular network in the ventricle in association with a reduction in WSS. However, rescuing notch signaling by Nrg‐1 mRNA partially restored trabeculation. Cloche mutant and tnnt2a MO also resulted in a significant reduction in trabeculation. The 4‐D optical SPIM technique has provided an unprecedented spatial and temporal resolution to link hemodynamics with development of trabeculationin live zebrafish embryos. Thus, light‐sheets elucidate hemodynamic modulation of trabeculation by activation of Notch signaling with translational implications in contractile function in ventricular non‐compactionin zebrafish model. Support or Funding Information This study was supported by the National Institutes of Health HL118650 (T.K.H.), HL083015 (T.K.H.), HD069305 (N.C.C., T.K.H.), HL111437 (T.K.H., N.C.C.), T32HL007895 (R.R.S.P.), and AHA Pre‐Doctoral Fellowship 15PRE21400019 (J.L.).
Type of Medium:
Online Resource
ISSN:
0892-6638
,
1530-6860
DOI:
10.1096/fasebj.30.1_supplement.554.3
Language:
English
Publisher:
Wiley
Publication Date:
2016
detail.hit.zdb_id:
1468876-1
detail.hit.zdb_id:
639186-2
SSG:
12
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