RESUMEN
The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at 20-25 somite stage in the distal zebrafish pronephros, stc1-expressing cells undergo apical constriction, and are subsequently extruded to form a distinct gland on top of the distal pronephric tubules at 50 âh post fertilization (hpf). Several transcription factors (e.g. Hnf1b, Irx3b, Tbx2a/b) and signaling pathways (e.g. Notch) control CS development. We report now that Fgf signaling is required to commit tubular epithelial cells to differentiate into stc1-expressing CS cells. Inhibition of Fgf signaling by SU5402, dominant-negative Fgfr1, or depletion of fgf8a prevented CS formation and stc1 expression. Ablation experiments revealed that CS have the ability to partially regenerate via active cell migration involving extensive filopodia and lamellipodia formation. Activation of Wnt signaling curtailed stc1 expression, but had no effect on CS formation. Thus, our observations identify Fgf signaling as a crucial component of CS cell fate commitment.
Asunto(s)
Diferenciación Celular , Glándulas Endocrinas/embriología , Factores de Crecimiento de Fibroblastos , Pronefro/embriología , Vía de Señalización Wnt , Proteínas de Pez Cebra , Pez Cebra , Animales , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Glicoproteínas/genética , Glicoproteínas/metabolismo , Pez Cebra/embriología , Pez Cebra/genética , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
Developing organisms need to adapt to environmental variations as well as to rapid changes in substrate availability and energy demands imposed by fast-growing tissues and organs. Little is known about the adjustments that kidneys undergo in response to these challenges. We performed single-cell RNA sequencing of zebrafish pronephric duct cells to understand how the developing kidney responds to changes in filtered substrates and intrinsic energy requirements. We found high levels of glucose transporters early in development and increased expression of monocarboxylate transporters at later times. This indicates that the zebrafish embryonic kidney displays a high glucose transporting capacity during early development, which is replaced by the ability to absorb monocarboxylates and amino acids at later stages. This change in transport capacity was accompanied by the upregulation of mitochondrial carriers, indicating a switch to increased oxidative phosphorylation to meet the increasing energy demand of a developing kidney.NEW & NOTEWORTHY The zebrafish embryonic kidney has high levels of glucose transporters during early development, which are replaced by monocarboxylate and amino acid transporters later on. Inhibition of Na+-glucose cotransporter-dependent glucose transport by sotagliflozin also increased slc2a1a expression, supporting the idea that the glucose transport capacity is dynamically adjusted during zebrafish pronephros development. Concurrent upregulation of mitochondrial SCL25 transporters at later stages supports the idea that the pronephros adjusts to changing substrate supplies and/or energy demands during embryonic development.
Asunto(s)
Metabolismo Energético/genética , Perfilación de la Expresión Génica , Pronefro/metabolismo , ARN Mensajero/genética , Análisis de la Célula Individual , Proteínas Transportadoras de Solutos/genética , Transcriptoma , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Regulación del Desarrollo de la Expresión Génica , Pronefro/embriología , ARN Mensajero/metabolismo , RNA-Seq , Proteínas Transportadoras de Solutos/metabolismo , Pez Cebra/embriología , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
BACKGROUND: Hepatitis E virus (HEV) infection is now recognized as a major cause of acute hepatitis worldwide. HEV specific antibodies develop shortly after infection and are thought to confer protection. CASE PRESENTATION: We report an immunocompromised patient who developed chronic HEV infection despite the presence of high level antibodies. HEV infection was detected using RT-PCR upon diagnostic evaluation due to increased liver enzymes. Upon retrospective analysis of stored serum samples we found that the patient was HEV RNA positive since 7 months. Chronic HEV infection was successfully treated with ribavirin. CONCLUSIONS: In conclusion, the patient suffered from a chronic course of HEV infection, which was successfully treated with ribavirin. Our case underlines the importance of RT-PCR for HEV diagnostics in immunosuppressed patients and supports the notion that HEV antibodies do not confer universal protection. Counseling patients at risk for chronic HEV infection seems advisable. The role of the humoral and T-cell mediated immune response in cases of HEV reinfection deserves further study.
