PHD1, PHD2, and PHD3 are prolyl hydroxylase domain proteins that regulate the stability of hypoxiainducible factor ␣ subunits (HIF-␣). To determine the roles of individual PHDs during mouse development, we disrupted all three Phd genes and found that Phd2 ؊/؊ embryos died between embryonic days 12.5 and 14.5 whereas Phd1؊/؊ or Phd3 ؊/؊ mice were apparently normal. In Phd2 ؊/؊ mice, severe placental and heart defects preceded embryonic death. Placental defects included significantly reduced labyrinthine branching morphogenesis, widespread penetration of the labyrinth by spongiotrophoblasts, and abnormal distribution of trophoblast giant cells. The expression of several trophoblast markers was also altered, including an increase in the spongiotrophoblast marker Mash2 and decreases in the labyrinthine markers Tfeb and Gcm1. In the heart, trabeculae were poorly developed, the myocardium was remarkably thinner, and interventricular septum was incompletely formed. Surprisingly, while there were significant global increases in HIF-␣ protein levels in the placenta and the embryo proper, there was no specific HIF-␣ increase in the heart. Taken together, these data indicate that among all three PHD proteins, PHD2 is uniquely essential during mouse embryogenesis.

Polycythemia is often associated with erythropoietin (EPO) overexpression and defective oxygen sensing. In normal cells, intracellular oxygen concentrations are directly sensed by prolyl hydroxylase domain (PHD)-containing proteins, which tag hypoxia-inducible factor (HIF) ␣ subunits for polyubiquitination and proteasomal degradation by oxygen-dependent prolyl hydroxylation. Here we show that different PHD isoforms differentially regulate HIF-␣ stability in the adult liver and kidney and suppress Epo expression and erythropoiesis through distinct mechanisms. Although Phd1 ؊/؊ or Phd3 ؊/؊ mice had no apparent defects, double knockout of Phd1 and Phd3 led to moderate erythrocytosis. HIF-2␣, which is known to activate Epo expression, accumulated in the liver. In adult mice deficient for PHD2, the prototypic Epo transcriptional activator HIF-1␣ accumulated in both the kidney and liver. Elevated HIF-1␣ levels were associated with dramatically increased concentrations of both Epo mRNA in the kidney and Epo protein in the serum, which led to severe erythrocytosis. In contrast, heterozygous mutation of Phd2 had no detectable effects on blood homeostasis. These findings suggest that PHD1/3 double deficiency leads to erythrocytosis partly by activating the hepatic HIF-2␣/Epo pathway, whereas PHD2 deficiency leads to erythrocytosis by activating the renal Epo pathway. (Blood. 2008; 111:3229-3235)

HEV markers (HEV RNA and anti-HEV) were detected in donors with elevated ALT levels who were widely distributed over Japan. The prevalence and incidence were higher in eastern Japan than in western Japan.

The spread of the domestic infection of HEV was observed in qualified blood donors in Japan. A higher prevalence of IgG anti-HEV was observed in male donors, older donors and in donors residing in eastern Japan. Further studies are necessary to clarify the potential risk of transfusion-transmission of HEV in Japan.

Malignant mesothelioma is an aggressive tumor of serosal surfaces, which is refractory to current treatment options. Arsenic trioxide (As 2 O 3 ) is used clinically to treat acute promyelocytic leukemia, and also to inhibit proliferation of several solid tumors including hepatoma, esophageal, and gastric cancer in vitro. Here we found that As 2 O 3 inhibited cell viability of a mesothelioma cell line, NCI-H2052. As 2 O 3 induced apoptosis of NCI-H2052 cells, which was accompanied by activation of c-Jun NH 2 -terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, and caspase-3. zVAD-fmk, a broad-spectrum caspase inhibitor, inhibited As 2 O 3 -induced apoptosis and activation of caspase-3, but not that of JNK1/2 and ERK1/2. Small interfering RNAs (siRNAs) targeting JNK1/2 suppressed As 2 O 3 -induced caspase-3 activation and apoptosis, indicating that JNK1/2 regulate As 2 O 3 -induced apoptosis though caspase cascade. Furthermore, JNK1 siRNA abrogated As 2 O 3 -induced JNK2 phosphorylation and JNK2 siRNA abrogated As 2 O 3 -induced JNK1 phosphorylation, suggesting that JNK1 and JNK2 interact with each other. Moreover, JNK1 siRNA, but not JNK2 siRNA, abrogated As 2 O 3 -induced ERK1/2 phosphorylation. JNK2 siRNA together with PD98059, a specific MAPK/ERK kinase inhibitor, suppressed As 2 O 3 -induced apoptosis more significantly than JNK2 siRNA alone. These results indicated that As 2 O 3 induces apoptosis of NCI-H2052 cells mainly through JNK1/2 activation, and that ERK1/2 is involved in As 2 O 3 -induced apoptosis when JNK1/2 are inactivated.