Iterative use of nuclear receptor Nr5a2 regulates multiple stages of liver and pancreas development

Abstract

The stepwise progression of common endoderm progenitors into differentiated liver and pancreas organs is regulated by a dynamic array of signals that are not well understood. The nuclear receptor subfamily 5, group A, member 2 gene nr5a2, also known as Liver receptor homolog-1 (Lrh-1) is expressed in several tissues including the developing liver and pancreas. Here, we interrogate the role of Nr5a2 at multiple developmental stages using genetic and chemical approaches and uncover novel pleiotropic requirements during zebrafish liver and pancreas development. Zygotic loss of nr5a2 in a targeted genetic null mutant disrupted the development of the exocrine pancreas and liver, while leaving the endocrine pancreas intact. Loss of nr5a2 abrogated exocrine pancreas markers such as trypsin, while pancreas progenitors marked by ptf1a or pdx1 remained unaffected, suggesting a role for Nr5a2 in regulating pancreatic acinar cell differentiation. In the developing liver, Nr5a2 regulates hepatic progenitor outgrowth and differentiation, as nr5a2 mutants exhibited reduced hepatoblast markers hnf4α and prox1 as well as differentiated hepatocyte marker fabp10a. Through the first in vivo use of Nr5a2 chemical antagonist Cpd3, the iterative requirement for Nr5a2 for exocrine pancreas and liver differentiation was temporally elucidated: chemical inhibition of Nr5a2 function during hepatopancreas progenitor specification was sufficient to disrupt exocrine pancreas formation and enhance the size of the embryonic liver, suggesting that Nr5a2 regulates hepatic versus pancreatic progenitor fate choice. Chemical inhibition of Nr5a2 at a later time during pancreas and liver differentiation was sufficient to block the formation of mature acinar cells and hepatocytes. These findings define critical iterative and pleiotropic roles for Nr5a2 at distinct stages of pancreas and liver organogenesis, and provide novel perspectives for interpreting the role of Nr5a2 in disease.

Forward Genetic Screens in Zebrafish Identify Pre-mRNA-Processing Pathways Regulating Early T Cell Development

“…( ela3l , try , amy2a , cpa1 ) genes suggest that the downstream effects of snapc3 , lsm8 , and tnpo3 mutations converge on malfunction of the exocrine pancreas (Table S7). This conclusion is supported by the fact that in all three mutants, aberrant splicing of the NR5A2 transcription factor also occurs (Table S6), which is required for liver and exocrine pancreas development (Nissim et al., 2016). We also note that the gene encoding the brush-border membrane glycoprotein Trehalase ( treh ) is affected by intron retention in all three mutants, adding to impaired absorption of carbohydrates.…”

Conserved and Exapted Functions of Nuclear Receptors in Animal Development

“…In the pancreas, LRH-1 functions in the formation of the multipotent progenitor cell, which eventually gives rise to a number of different pancreatic cell types [248]. In zebrafish, LRH-1 also functions in gut, liver, and pancreas development and synergizes with Wnt signaling pathways [249,250]. Both SF-1 and LRH-1 bind and respond to phospholipids [251].…”

Making It New Again

“…Additional work from the Goessling group demonstrated that nuclear receptor subfamily 5, group A, member 2 gene ( nr5a2 ) is also important for determining liver-pancreas fate. By using a combination of morpholinos, mutants and drugs to target Nr5a2 in developing zebrafish, they identified a requirement during exocrine, but not endocrine, pancreas development, and for liver growth (Nissim et al, 2016). This suggests that Nr5a2 has different roles at different states of development, first, in priming the hepatopancreatic progenitors, and then in their outgrowth.…”