Ko Onodera

Rescue of the embryonic lethal hematopoietic defect reveals a critical role for GATA‐2 in urogenital development

Mutations resulting in embryonic or early postnatal lethality could mask the activities of any gene in unrelated and temporally distinct developmental pathways. Targeted inactivation of the transcription factor GATA‐2 gene leads to mid‐gestational death as a consequence of hematopoietic failure. We show here that a 250 kbp GATA‐2 yeast artificial chromosome (YAC) is expressed strongly in both the primitive and definitive hematopoietic compartments, while two smaller YACs are not. This largest YAC also rescues hematopoiesis in vitro and in vivo, thereby localizing the hematopoietic regulatory cis element(s) to between 100 and 150 kbp 5′ to the GATA‐2 structural gene. Introducing the YAC transgene into the GATA‐2−/− genetic background allows the embryos to complete gestation; however, newborn rescued pups quickly succumb to lethal hydroureternephrosis, and display a complex array of genitourinary abnormalities. These findings reveal that GATA‐2 plays equally vital roles in urogenital and hematopoietic development.

Validation of the Multiple Sensor Mechanism of the Keap1-Nrf2 System

The Keap1-Nrf2 system plays a critical role in cellular defense against electrophiles and reactive oxygen species. Keap1 possesses a number of cysteine residues, some of which are highly reactive and serves as sensors for these insults. Indeed, point mutation of Cys151 abrogates the response to certain electrophiles. However, this mutation does not affect the other set of electrophiles, suggesting that multiple sensor systems reside within the cysteine residues of Keap1. The precise contribution of each reactive cysteine to the sensor function of Keap1 remains to be clarified. To elucidate the contribution of Cys151 in vivo, in this study we adopted transgenic complementation rescue assays. Embryonic fibroblasts and primary peritoneal macrophages were prepared from mice expressing the Keap1-C151S mutant. These cells were challenged with various Nrf2 inducers. We found that some of the inducers triggered only marginal responses in Keap1-C151S-expressing cells, while others evoked responses in a comparable magnitude to those observed in the wild-type cells. We found that tert-butyl hydroquinone, diethylmaleate, sulforaphane, and dimethylfumarate were Cys151 preferable, whereas 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PG-J(2)), 2-cyano-3,12 dioxooleana-1,9 diene-28-imidazolide (CDDO-Im), ebselen, nitro-oleic acid, and cadmium chloride were Cys151 independent. Experiments with embryonic fibroblasts and primary macrophages yielded consistent results. Experiments testing protective effects against the cytotoxicity of 1-chloro-2,4-dinitrobenzene of sulforaphane and 15d-PG-J(2) in Keap1-C151S-expressing macrophages revealed that the former inducer was effective, while the latter was not. These results thus indicate that there exists distinct utilization of Keap1 cysteine residues by different chemicals that trigger the response of the Keap1-Nrf2 system, and further substantiate the notion that there are multiple sensing mechanisms within Keap1 cysteine residues.

Perinatal synthetic lethality and hematopoietic defects in compound mafG::mafK mutant mice

Prior studies exploring the mechanisms controlling erythroid gene regulation implicated MARE (Maf recognition element) cis‐elements as crucial to the transcriptional activity of many erythroid genes. Numerous transcription factors can elicit responses through MAREs, including not only the AP‐1 family proteins, but also a growing list of factors composed of Cap‐N‐Collar (CNC)–small Maf heterodimers. While these factors can activate transcription from MAREs in co‐transfection assays, mouse germline mutations in cnc genes tested to date have failed to reveal primary erythroid phenotypes. Here we report that after combining the mafK and mafG targeted null alleles, mutant animals display several synthetic phenotypes, including erythroid deficiencies. First, compound homozygous small maf gene mutants survive embryogenesis, but die postnatally. Secondly, compound mutant animals develop severe neurological disorders. Thirdly, they exhibit an exacerbated mafG deficiency in megakaryopoiesis, specifically in proplatelet formation, resulting in profound thrombocytopenia. Finally, the compound mutant animals develop severe anemia accompanied by abnormal erythrocyte morphology and membrane protein composition. These data provide direct evidence that the small Maf transcription factors play an important regulatory role in erythropoiesis.

Prospective Comparison of Surgery Alone and Chemoradiotherapy With Selective Surgery in Resectable Squamous Cell Carcinoma of the Esophagus

PURPOSE Esophagectomy remains the mainstay treatment for esophageal cancer, although retrospective studies have suggested that chemoradiotherapy (CRT) is as effective as surgery. To determine whether CRT can substitute for surgery as the primary treatment modality, we performed a prospective direct comparison of outcomes after treatment in patients with resectable esophageal cancer who had received CRT and those who had undergone surgery. METHODS AND MATERIALS Eligible patients had resectable T1-3N0-1M0 thoracic esophageal cancer. After the surgeon explained the treatments in detail, the patients selected either CRT (CRT group) or surgery (OP group). The CRT course consisted of two cycles of cisplatin and fluorouracil with split-course concurrent radiotherapy of 60Gy in 30 fractions. Patients with progressive disease during CRT and/or with persistent or recurrent disease after CRT underwent salvage resection. RESULTS Of 99 eligible patients with squamous cell carcinoma registered between January 2001 and December 2005, 51 selected CRT and 48 selected surgery. Of the patients in the CRT group, 13 (25.5%) underwent esophagectomy as salvage therapy. The 3- and 5-year survival rates were 78.3% and 75.7%, respectively, in the CRT group compared with 56.9% and 50.9%, respectively, in the OP group (p = 0.0169). Patients in the OP group had significantly more metastatic recurrence than those in the CRT group. CONCLUSIONS Treatment outcomes among patients with resectable thoracic esophageal squamous cell carcinoma were comparable or superior after CRT (with salvage therapy if needed) to outcomes after surgery alone.

Characterization of the Murine mafF Gene

Small Maf proteins are obligatory heterodimeric partner molecules of mammalian Cap’n’Collar proteins that together control a wide variety of eukaryotic genes. Although both MafK and MafG are expressed in overlapping but distinct tissue distribution patterns during embryonic development, the physiological consequences of loss-of-function mutations in either gene are modest. This suggested that compensation by the third small Maf protein, MafF, might be a major reason for such mild phenotypes and that further analysis of MafF might therefore provide important insights for understanding small Maf regulatory function(s). We therefore cloned, mapped, transcriptionally and developmentally characterized, and finally disrupted themafF gene. We show that murine mafF is transcriptionally regulated by three different promoters and is most abundantly expressed in the lung. The lacZ gene inserted into the mafF locus revealed prominent expression sites in the gut, lung, liver, outflow tract of the heart, cartilage, bone membrane, and skin but not in hematopoietic cells at any developmental stage. Homozygous mafF null mutant mice were born in a normal Mendelian ratio and displayed no obvious functional deficiencies, indicating that MafF activity may be dispensable even in tissues where the expression of other small Maf proteins is quite low.

Upstream and downstream of erythroid transcription factor GATA-1

All mature blood lineages in the peripheral circulation are derived from pluripotent haematopoietic stem cell. Progressive lineage‐restriction of this stem cell is executed, in part, by the interplay and cross‐talk between a host of lineage‐restricted as well as ubiquitous transcription factors. To elucidate the regulatory mechanisms underlying the erythroid gene regulation, it is essential to understand how individual transcription factors contribute to the regulation of specific target genes, and how these erythroid transcription factor genes are regulated in turn. These key issues of mammalian development have been addressed by examining the activities controlling the prototype transcription factor, GATA‐1. The transcriptional regulation of GATA‐1 has been intensively investigated, thereby leading to the identification of its developmental stage‐specific regulatory sequences. Loss‐of‐function mutant animals, combined with specific marking of the primitive and definitive erythroid lineages have also shed new insight into how GATA‐1 activity is required in vivo at specific developmental stages. Procedures have also been developed for ascertaining whether or not the GATA‐1 protein actually binds in vivo to regulatory GATA motifs in candidate target genes. Application of a similar multifaceted approach should enable investigators to examine the physiological roles that any transcription factor might play in vivo during the differentiation of any well defined cell lineage.

Long-Term Results of Radiochemotherapy for Solitary Lymph Node Metastasis After Curative Resection of Esophageal Cancer

PURPOSE To evaluate the long-term efficacy and toxicity of definitive radiochemotherapy for solitary lymph node metastasis after curative surgery of esophageal cancer. METHODS AND MATERIALS We performed a retrospective review of 35 patients who underwent definitive radiochemotherapy at Tohoku University Hospital between 2000 and 2009 for solitary lymph node metastasis after curative esophagectomy with lymph node dissection for esophageal cancer. Radiotherapy doses ranged from 60 to 66 Gy (median, 60 Gy). Concurrent chemotherapy was platinum based in all patients. The endpoints of the present study were overall survival, cause-specific survival, progression-free survival, irradiated-field control, overall tumor response, and prognostic factors. RESULTS The median observation period for survivors was 70.0 months. The 5-year overall survival was 39.2% (median survival, 39.0 months). The 5-year cause-specific survival, progression-free survival, and irradiated-field control were 43.3%, 31.0% and 59.9%, respectively. Metastatic lesion, size of the metastatic lymph node, and performance status before radiochemotherapy were significantly correlated with prognosis. Complete response and partial response were observed in 22.9% and 57.1% of the patients, respectively. There was no Grade 3 or higher adverse effect based on the Common Terminology Criteria for Adverse Events (CTCAE v3.0) in the late phase. CONCLUSIONS Based on our study findings, approximately 40% of patients with solitary lymph node metastasis after curative resection for esophageal cancer have a chance of long-term survival with definitive radiochemotherapy.

One enhancer mediates mafK transcriptional activation in both hematopoietic and cardiac muscle cells

Members of the small Maf family of transcription factors play important roles in hematopoiesis. Using transgenic assays, we discovered a tissue‐specific enhancer 3′ to the mafK gene. This enhancer directs mafK transcription in hematopoietic as well as in developing cardiac muscle cells, and was thus designated the hematopoietic and cardiac enhancer of mafK (HCEK). Only two of four GATA consensus motifs identified within HCEK contributed to enhancer activity, and both of these sites were required for both cardiac and hematopoietic transcriptional activation. The expression profile of MafK significantly overlapped that of GATA‐1 in hematopoietic cells and of GATA‐4/‐6 in cardiac tissues. Each of these GATA factors bound with high specificity to both of the critical GATA sites in HCEK. Hence, the mafK gene is regulated by different GATA proteins in the hematopoietic and cardiac compartments through the same two GATA‐binding sites in HCEK. These data provide the first in vivo demonstration that distinct members of a related transcription factor family activate the tissue‐specific expression of a single target gene using the same cis‐regulatory element.

Esophagectomy using a thoracoscopic approach with an open laparotomic or hand-assisted laparoscopic abdominal stage for esophageal cancer: analysis of survival and prognostic factors in 315 patients.

&NA;Survival and prognostic factors were analyzed in 315 patients with esophageal cancer undergoing thoracoscopic-assisted esophagectomy (TAE). The 5-year survival rate of 57.8% was satisfactory, indicating the oncological feasibility of TAE. Perioperative outcomes affected overall survival in the whole cohort but not in the subgroup treated with 2 endoscopic stages. Objective:To estimate the oncological feasibility of thoracoscopic-assisted esophagectomy (TAE) for esophageal cancer and to clarify the prognostic impact of perioperative factors after TAE. Background:Favorable perioperative outcomes of TAE versus open surgery have been demonstrated. However, survival data after TAE in a large cohort are limited, and no information on the prognostic influence of perioperative factors after TAE is available. Methods:Prospectively collected data for 315 patients undergoing TAE for esophageal cancer were analyzed. Survival was compared with the Kaplan-Meier analysis and Cox regression analysis between 2 surgical approaches: thoracoscopic and hand-assisted laparoscopic esophagectomy (THLE) and thoracoscopic and open laparotomic esophagectomy (TOE). Factors affecting overall survival were identified with Cox multivariate regression analysis in the whole cohort and the THLE subgroup. Results:THLE and TOE were performed in 153 and 162 patients, respectively. The overall 5-year survival of the whole cohort was 57.8%, with no difference between the THLE and the TOE group. Multivariate analysis of the 315 patients identified the following prognostic factors: blood loss, blood transfusion, intensive care unit stay, cardiovascular complications, pathological T and N stages, lymphatic invasion, intramural metastasis, and number of metastatic nodes. In the THLE subgroup, cerebral comorbidity, histological subtype, pathological T stage, and number of metastatic nodes were independent prognostic factors. Conclusions:TAE was oncologically feasible. Perioperative factors affected survival in the whole cohort, but did not in the THLE subgroup. However, the reduced perioperative factor effect in this subgroup would be small because the survival rates of the 2 surgical approaches were equal.

Use of the pinna reflex as a test of hearing in mutant mice

Although it is a gross measure, the pinna reflex test is easily administered and is, therefore, incorporated as a general screening tool in mutagenesis programs. Our recent application of this approach indicated that mutant mice lacking one of the small Maf proteins, in this case MafG, failed to exhibit a pinna reflex. In contrast, littermate controls, with the same mixed 129/CD1 background, and including both wild type and heterozygous mutant animals, passed the test. Because previous studies indicate that mafG is expressed in both cochlear and vestibular parts of the mouse inner ear, the source of this ‘presumed deafness’ was further assessed by making round window recordings to determine compound action potential thresholds. Auditory brainstem responses were also acquired to assess function along portions of the central auditory pathway. In all cases, responses in homozygous mutants (–/–) were comparable to those obtained from littermate controls, either wild type (+/+) or heterozygous mutants (+/–). Gross anatomy of the organ of Corti was also found to be similar in all three groups of mice. Hence, the lack of a pinna reflex must relate to nonauditory causes.