AUTHOR=Zhang Chong , Huang Rui , Ma Xirui , Chen Jiehui , Han Xinlu , Li Li , Luo Lingfei , Ruan Hua , Huang Honghui 

TITLE=The Ribosome Biogenesis Factor Ltv1 Is Essential for Digestive Organ Development and Definitive Hematopoiesis in Zebrafish

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.704730

DOI=10.3389/fcell.2021.704730

ISSN=2296-634X

ABSTRACT=<p>Ribosome biogenesis is a fundamental activity in cells. Ribosomal dysfunction underlies a category of diseases called ribosomopathies in humans. The symptomatic characteristics of ribosomopathies often include abnormalities in craniofacial skeletons, digestive organs, and hematopoiesis. Consistently, disruptions of ribosome biogenesis in animals are deleterious to embryonic development with hypoplasia of digestive organs and/or impaired hematopoiesis. In this study, <italic>ltv1</italic>, a gene involved in the small ribosomal subunit assembly, was knocked out in zebrafish by clustered regularly interspaced short palindromic repeats (CRISPRs)/CRISPR associated protein 9 (Cas9) technology. The recessive lethal mutation resulted in disrupted ribosome biogenesis, and <italic>ltv1</italic><sup>Δ14/Δ14</sup> embryos displayed hypoplastic craniofacial cartilage, digestive organs, and hematopoiesis. In addition, we showed that the impaired cell proliferation, instead of apoptosis, led to the defects in exocrine pancreas and hematopoietic stem and progenitor cells (HSPCs) in <italic>ltv1</italic><sup>Δ14/Δ14</sup> embryos. It was reported that loss of function of genes associated with ribosome biogenesis often caused phenotypes in a P53-dependent manner. In <italic>ltv1</italic><sup>Δ14/Δ14</sup> embryos, both P53 protein level and the expression of <italic>p53</italic> target genes, Δ<italic>113p53</italic> and <italic>p21</italic>, were upregulated. However, knockdown of <italic>p53</italic> failed to rescue the phenotypes in <italic>ltv1</italic><sup>Δ14/Δ14</sup> larvae. Taken together, our data demonstrate that LTV1 ribosome biogenesis factor (Ltv1) plays an essential role in digestive organs and hematopoiesis development in zebrafish in a P53-independent manner.</p>