No abstract

Kidney formation involves patterning events that induce renal progenitors to form nephrons with an intricate composition of multiple segments. Here, we performed a chemical genetic screen using zebrafish and discovered that prostaglandins, lipid mediators involved in many physiological functions, influenced pronephros segmentation. Modulating levels of prostaglandin E2 (PGE2) or PGB2 restricted distal segment formation and expanded a proximal segment lineage. Perturbation of prostaglandin synthesis by manipulating Cox1 or Cox2 activity altered distal segment formation and was rescued by exogenous PGE2. Disruption of the PGE2 receptors Ptger2a and Ptger4a similarly affected the distal segments. Further, changes in Cox activity or PGE2 levels affected expression of the transcription factors irx3b and sim1a that mitigate pronephros segment patterning. These findings show for the first time that PGE2 is a regulator of nephron formation in the zebrafish embryonic kidney, thus revealing that prostaglandin signaling may have implications for renal birth defects and other diseases.DOI: http://dx.doi.org/10.7554/eLife.17551.001

Multiciliated cells (MCCs) are specialized epithelia with apical bundles of motile cilia that direct fluid flow. MCC dysfunction is associated with human diseases of the respiratory, reproductive, and central nervous systems. Further, the appearance of renal MCCs has been cataloged in several kidney conditions, where their function is unknown. Despite their pivotal health importance, many aspects of MCC development remain poorly understood. Here, we utilized a chemical screen to identify molecules that affect MCC ontogeny in the zebrafish embryo kidney, and found prostaglandin signaling is essential both for renal MCC progenitor formation and terminal differentiation. Moreover, we show that prostaglandin activity is required downstream of the transcription factorets variant 5a(etv5a) during MCC fate choice, where modulating prostaglandin E2(PGE2) levels rescued MCC number. The discovery that prostaglandin signaling mediates renal MCC development has broad implications for other tissues, and could provide insight into a multitude of pathological states.

No abstract

The zebrafish kidney is conserved with other vertebrates, making it an excellent genetic model to study renal development. The kidney collects metabolic waste using a blood filter with specialized epithelial cells known as podocytes. Podocyte formation is poorly understood but relevant to many kidney diseases, as podocyte injury leads to progressive scarring and organ failure. zeppelin (zep) was isolated in a forward screen for kidney mutants and identified as a homozygous recessive lethal allele that causes reduced podocyte numbers, deficient filtration, and fluid imbalance. Interestingly, zep mutants had a larger interrenal gland, the telostean counterpart of the mammalian adrenal gland, which suggested a fate switch with the related podocyte lineage since cell proliferation and cell death were unchanged within the shared progenitor field from which these two identities arise. Cloning of zep by whole genome sequencing (WGS) identified a splicing mutation in breast cancer 2, early onset (brca2)/fancd1, which was confirmed by sequencing of individual fish. Several independent brca2 morpholinos (MOs) phenocopied zep, causing edema, reduced podocyte number, and increased interrenal cell number. Complementation analysis between zep and brca2ZM_00057434-/- zebrafish, which have an insertional mutation, revealed that the interrenal lineage was expanded. Importantly, overexpression of brca2 rescued podocyte formation in zep mutants, providing critical evidence that the brca2 lesion encoded by zep specifically disrupts the balance of nephrogenesis. Taken together, these data suggest for the first time that brca2/fancd1 is essential for vertebrate kidney ontogeny. Thus, our findings impart novel insights into the genetic components that impact renal development, and because BRCA2/FANCD1 mutations in humans cause Fanconi anemia and several common cancers, this work has identified a new model to further study brca2/fancd1 in disease.