PT  - JOURNAL ARTICLE
AU  - Sapthaswaran Veerapathiran
AU  - Cathleen Teh
AU  - Shiwen Zhu
AU  - Indira Kartigayen
AU  - Vladimir Korzh
AU  - Paul T. Matsudaira
AU  - Thorsten Wohland
TI  - Wnt3 distribution in the zebrafish brain is determined by expression, diffusion and multiple molecular interactions
AID  - 10.1101/2020.05.29.124560
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.29.124560
4099  - http://biorxiv.org/content/early/2020/05/30/2020.05.29.124560.short
4100  - http://biorxiv.org/content/early/2020/05/30/2020.05.29.124560.full
AB  - Wnt3 proteins are lipidated and glycosylated, secreted signaling molecules that play an important role in zebrafish neural patterning and brain development. However, the transport mechanism of lipid-modified Wnts through the hydrophilic extracellular environment for long-range action remains unresolved. Here, we determine how Wnt3 accomplishes long-range distribution in the zebrafish brain. First, we characterize the Wnt3-producing source and Wnt3-receiving target regions. Subsequently, we analyze Wnt3 mobility at different length scales by fluorescence correlation spectroscopy and fluorescence recovery after photo-bleaching. We demonstrate that Wnt3 spreads extracellularly and interacts with heparan sulfate proteoglycans (HSPG). We then determine the binding affinity of Wnt3 to its receptor, Frizzled1 (Fzd1), using fluorescence cross-correlation spectroscopy, and show that the co-receptor, low-density lipoprotein receptor-related protein 5 (Lrp5), is required for Wnt3-Fzd1 interaction. Our results are consistent with the extracellular distribution of Wnt3 by a diffusive mechanism that is modified by tissue morphology, interactions with HSPG and Lrp5-mediated receptor binding, to regulate zebrafish brain development.Competing Interest StatementThe authors have declared no competing interest.