Eya1 interacts with Six2 and Myc to regulate expansion of the nephron progenitor pool during nephrogenesis.

Self-renewal and proliferation of nephron progenitor cells and the decision to initiate nephrogenesis are crucial events directing kidney development. Despite recent advancements in defining lineage and regulators for the progenitors, fundamental questions about mechanisms driving expansion of the progenitors remain unanswered. Here we show that Eya1 interacts with Six2 and Myc to control self-renewing cell activity. Cell fate tracing reveals a developmental restriction of the Eya1(+) population within the intermediate mesoderm to nephron-forming cell fates and a common origin shared between caudal mesonephric and metanephric nephrons. Conditional inactivation of Eya1 leads to loss of Six2 expression and premature epithelialization of the progenitors. Six2 mediates translocation of Eya1 to the nucleus, where Eya1 uses its threonine phosphatase activity to control Myc phosphorylation/dephosphorylation and function in the progenitor cells. Our results reveal a functional link between Eya1, Six2, and Myc in driving the expansion and maintenance of the multipotent progenitors during nephrogenesis.

Prenatal zinc supplementation of zinc-adequate rats adversely affects immunity in offspring.

We previously showed that zinc (Zn) supplementation of Zn-adequate dams induced immunosuppressive effects that persist in the offspring after weaning. We investigated whether the immunosuppressive effects were due to in utero exposure and/or mediated via milk using a cross-fostering design. Pregnant rats with adequate Zn nutriture were supplemented with either Zn (1.5 mg Zn in 10% sucrose) or placebo (10% sucrose) during pregnancy (3 times/wk). At postnatal d 3, 4 pups of Zn-supplemented dams (Zn-P) were exchanged with 4 of placebo-supplemented dams (P-Zn). The remaining pups continued with their biological mothers (Zn-Zn and P-P). Pups were orally immunized with dinitrophenol ovalbumin-BSA and/or cholera toxin B subunit (CTB), and serum Zn concentrations and cellular and humoral responses were assessed. Pups of Zn-supplemented dams had higher serum Zn when fostered either by placebo- or Zn-supplemented dams compared to pups of placebo-supplemented dams (P < 0.01). Postnatal Zn exposure reduced the number of Peyer's patches in both the Zn-Zn and P-Zn groups (P < 0.01). Prenatal Zn exposure suppressed CTB- (P = 0.05) and BSA-specific proliferation response of Peyer's Patch lymphocytes (P = 0.07). Prenatal Zn exposure effects on the splenocyte cytokine response were differently influenced by fostering mothers' Zn status. Antigen presenting cell (APC) activity of splenocytes was lower in the Zn-Zn group than in the P-P group (P < 0.08). In conclusion, prenatal Zn exposure increases serum Zn levels in pups and suppresses antigen-specific proliferation and antibody responses and APC function, whereas postnatal exposure may suppress the mucosal immune reservoir.

Expression of human factors CD81, claudin-1, scavenger receptor, and occludin in mouse hepatocytes does not confer susceptibility to HCV entry.

No suitable mouse model is available for studying chronic liver disease caused by hepatitis C virus (HCV). CD81, claudin-1, scavenger receptor class B type I, and occludin were recently reported to be the important factors in HCV entry into hepatocytes. We made transgenic mice (Alb-CCSO) expressing the four human proteins and examined whether HCV from a patient serum or HCV pseudoparticles (HCVpp) were capable of infecting them. HCV was not detected in the mouse serum after injecting the mice with HCV from a patient serum. We also found no indications of HCVpp entry into primary hepatocytes from Alb-CCSO mice. In addition, HCV-infectible Hep3B cells were fused with HCV-resistant primary mouse hepatocytes and the fused cells showed 35-fold lower infectivity compared to wild-type Hep3B cells, indicating that primary mouse hepatocytes have the inhibitory factor(s) in HCVpp entry. Our results suggest that the expression of the human factors does not confer susceptibility to HCV entry into the liver.

Irxl1 mutant mice show reduced tendon differentiation and no patterning defects in musculoskeletal system development.

Irxl1 (Iroquois-related homeobox like-1) is a newly identified three amino-acid loop extension (TALE) homeobox gene, which is expressed in various mesoderm-derived tissues, particularly in the progenitors of the musculoskeletal system. To analyze the roles of Irxl1 during embryonic development, we generated mice carrying a null allele of Irxl1. Mice homozygous for the targeted allele were viable, fertile, and showed reduced tendon differentiation. Skeletal morphology and skeletal muscle weight in Irxl1-knockout mice appeared normal. Expression patterns of several marker genes for cartilage, tendon, and muscle progenitors in homozygous mutant embryos were unchanged. These results suggest that Irxl1 is required for the tendon differentiation but dispensable for the patterning of the musculoskeletal system in development.

The mouse forkhead gene Foxp2 modulates expression of the lung genes.

AIMS: Foxp2 is expressed in the lung during mouse development. A monoclonal anti-mouse Foxp2 antibody was created to determine the expression pattern in the developing lung. Next, transcriptional control of two lung genes, CC10 and surfactant protein C (SPC) genes, by Foxp2 was investigated in H441 and A549 cells. Thirdly, expression patterns of Foxp2 and Foxf2 were compared in the developing lung. Finally, Foxp2 expression was determined in the Foxf2-null mice. MAIN METHODS: Immunohistochemical staining and in situ hybridization were applied to the sections of lungs in the developing embryos. KEY FINDINGS: Monoclonal anti-Foxp2 antibody demonstrated that Foxp2 was expressed in the bronchial epithelium at E10.5 and its expression became restricted to the distal portion of the elongating bronchiolar epithelium and finally to type II alveolar epithelial cells around birth and in the adult. Foxp2 activated the SPC gene promoter in the presence of Nkx2.1 in A549 cells while it repressed the CC10 gene promoter in H441 cells. Next, the expression domains of the Foxp2 and Foxf2 were found to be exclusive in the lung. Finally, the expression of Foxp2 did not change in the lung of Foxf2-null mice. SIGNIFICANCE: The Foxp2 protein is expressed in the growing distal edge of airway epithelium. When the bronchiolus elongates, Foxp2 suppresses CC10 expression. When the lung alveolus is formed, Foxp2 modulates the Nkx2.1-mediated SPC expression in type II alveolar cells. Foxp2 and Foxf2 independently play distinct roles in the alveoli and the mesenchyme, respectively.