The BHLH Protein Nulp1 is Essential for Femur Development Via Acting As a Cofactor in Wnt Signaling in Drosophila

Overview

Journal Curr Mol Med

Publisher Bentham Science Publishers

Specialty Molecular Biology

Date 2018 Feb 14

PMID 29437009

Authors

Q Zeng

Y Wan

P Zhu

M Zhao

F Jiang

J Chen

M Tang

X Zhu

Y Li

H Zha

Y Wang

M Hu

X Mo

Y Zhang

Y Chen

X Ye

R Bodmer

K Ocorr

Z Jiang

J Zhuang

W Yuan

X Wu

Affiliations

Soon will be listed here.

Abstract

Background: The basic helix-loop-helix (bHLH) protein families are a large class of transcription factors, which are associated with cell proliferation, tissue differentiation, and other important development processes. We reported that the Nuclear localized protein-1 (Nulp1) might act as a novel bHLH transcriptional factor to mediate cellular functions. However, its role in development in vivo remains unknown.

Methods: Nulp1 (dNulp1) mutants are generated by CRISPR/Cas9 targeting the Domain of Unknown Function (DUF654) in its C terminal. Expression of Wg target genes are analyzed by qRT-PCR. We use the Top-Flash luciferase reporter assay to response to Wg signaling.

Results: Here we show that Drosophila Nulp1 (dNulp1) mutants, generated by CRISPR/Cas9 targeting the Domain of Unknown Function (DUF654) in its C terminal, are partially homozygous lethal and the rare escapers have bent femurs, which are similar to the major manifestation of congenital bent-bone dysplasia in human Stuve- Weidemann syndrome. The fly phenotype can be rescued by dNulp1 over-expression, indicating that dNulp1 is essential for fly femur development and survival. Moreover, dNulp1 overexpression suppresses the notch wing phenotype caused by the overexpression of sgg/GSK3β, an inhibitor of the canonical Wnt cascade. Furthermore, qRT-PCR analyses show that seven target genes positively regulated by Wg signaling pathway are down-regulated in response to dNulp1 knockout, while two negatively regulated Wg targets are up-regulated in dNulp1 mutants. Finally, dNulp1 overexpression significantly activates the Top-Flash Wnt signaling reporter.

Conclusion: We conclude that bHLH protein dNulp1 is essential for femur development and survival in Drosophila by acting as a positive cofactor in Wnt/Wingless signaling.

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