Project description:Injuries of the zebrafish kidney are rapidly repaired by a migratory response in two to three day-old embryos. While this migratory repair process re-establishes the integrity of the pronephric tubules independently of proliferation, fluid flow, intact cilia, or Wnt signaling, pronephros injuries before 36 hours post fertilization were repaired by a purse string-like mechanism that irreversibly occluded the pronephric tubules. Comparing the gene expression profiles between these two developmental stages and focusing on up-regulated zebrafish pronephros genes, we identified cxcl12a and myca as potential candidates orchestrating the migratory repair process. Zebrafish lines with either cxcl12a or cxcr4b mutations displayed striking repair abnormalities, confirming the requirement for cxc12a/cxcr4b signaling to override the ongoing collective cell migration and repair the pronephros injury. However, in contrast to the collective cell migration of the posterior lateral line primordium, cxc12a/cxcr4b signaling was dispensable for normal pronephros development. Zebrafish myca, the pronephros-specific homologue of human MYC, was also increased in cells participating in the repair response. The defective repair response caused by knockdown of myca resembled the abnormalities observed in cxcx12a/cxcr4b-deficient zebrafish, and was partially rescued by cxcr4b mRNA, suggesting that myca acts in part through up-regulating cxcr4b expression during the migration-based repair process. Kidney-specific knockout of Cxcl12 and Myc suppressed mitochondrial functions, reduced retinoic acid receptor signaling, and delayed the recovery after ischemic/reperfusion injury in mice. Tretinoin, known to stimulate Cxcr4 expression and mitochondrial metabolism, accelerated renal recovery. Thus, the zebrafish pronephros injury mode provides a systematic approach to identify molecules involved in the immediate repair response after kidney injury, and to design strategies to ameliorate this severe complication of human disease.
Project description:In mammals, retinal damage is followed by Müller glia cell activation and proliferation. While retinal gliosis persists in adult mammals after an insult or disease, some vertebrates, including zebrafish, have the capacity to regenerate. We believe we are the first group to show that gliosis is a fibrotic-like process in mammals’ eyes caused by differential activation of canonical and non-canonical TGFβ signaling pathways.
Project description:Kidney injury is a common complication of severe disease. Here, we report that injuries of the zebrafish embryonal kidney are rapidly repaired by a migratory response in 2-, but not in 1-day-old embryos. Gene expression profiles between these two developmental stages identify cxcl12a and myca as candidates involved in the repair process. Zebrafish embryos with cxcl12a, cxcr4b, or myca deficiency display repair abnormalities, confirming their role in response to injury. In mice with a kidney-specific knockout, Cxcl12 and Myc gene deletions suppress mitochondrial metabolism and glycolysis, and delay the recovery after ischemia/reperfusion injury. Probing these observations in zebrafish reveal that inhibition of glycolysis slows fast migrating cells and delays the repair after injury, but does not affect the slow cell movements during kidney development. Our findings demonstrate that Cxcl12 and Myc facilitate glycolysis to promote fast migratory responses during development and repair, and potentially also during tumor invasion and metastasis.
Project description:Neural crest cells are migratory progenitor cells that contribute to nearly all tissues and organs throughout the body. Their formation, migration and differentiation are regulated by a multitude of signaling pathways, that when disrupted can lead to disorders termed neurocristopathies. While work in avian and amphibian species has revealed essential factors governing the specification and induction of neural crest cells during gastrulation and neurulation in non-mammalian species, their functions do not appear to be conserved in mice, leaving major gaps in our understanding of neural crest cell formation in mammals. Here we describe Germ Cell Nuclear Factor (GCNF/Nr6a1), an orphan nuclear receptor, as a critical regulator of neural crest cell formation in mice. Gcnf null mutant mice, exhibit a major disruption of neural crest cell formation. The purpose of this experiment is to examine gene expression changes in response to Gcnf mutation in E9.0 mouse embryos.
