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Translesion synthesis (TLS) polymerases mediate DNA damage bypass during replication. The TLS polymerase Rev1 has two important functions in the TLS pathway, including dCMP transferase activity and acting as a scaffolding protein for other TLS polymerases at the C‐terminus. Because of the former activity, Rev1 bypasses apurinic/apyrimidinic sites by incorporating dCMP, whereas the latter activity mediates assembly of multipolymerase complexes at the DNA lesions. We generated rev1 mutants lacking each of these two activities in Oryzias latipes (medaka) fish and analyzed cytotoxicity and mutagenicity in response to the alkylating agent diethylnitrosamine (DENA). Mutant lacking the C‐terminus was highly sensitive to DENA cytotoxicity, whereas mutant with reduced dCMP transferase activity was slightly sensitive to DENA cytotoxicity, but exhibited a higher tumorigenic rate than wild‐type fish. There was no significant difference in the frequency of DENA‐induced mutations between mutant with reduced dCMP transferase activity and wild‐type cultured cell. However, loss of heterozygosity (LOH) occurred frequently in cells with reduced dCMP transferase activity. LOH is a common genetic event in many cancer types and plays an important role on carcinogenesis. To our knowledge, this is the first report to identify the involvement of the catalytic activity of Rev1 in suppression of LOH., LOH is a common genetic event in many cancer types and plays an important role on carcinogenesis. We found defect in the catalytic activity of rev1 exhibited a higher tumorigenic rate and high frequency of LOH. To our knowledge, this is the first report to identify the involvement of the catalytic activity of Rev1 in suppression of LOH.

Genetic mosaic analysis is a powerful means of addressing the sites of gene action in multicellular organisms. In conventional genetic analysis, the generation of desired mosaic patterns is difficult to control due to the randomness of generating the genetic mosaic which often renders the analysis laborious and time consuming. The infrared laser-evoked gene operator (IR-LEGO) microscope system facilitates genetic mosaic analysis by enabling gene induction in targeted single cells in a living organism. However, the level of gene induction is not controllable due to the usage of a heat-shock promoter. Here, we applied IR-LEGO to examine the cell-cell interactions mediated by semaphoring-plexin signaling in Caenorhabditis elegans by inducing wild-type semaphorin/plexin in single cells within the population of mutant cells lacking the relevant proteins. We found that the cell contact-dependent termination of the extension of vulval precursor cells is elicited by the forward signaling mediated by the semaphorin receptor, PLX-1, but not by the reverse signaling via the transmembrane semaphorin, SMP-1. By utilizing Cre/loxP recombination coupled with the IR-LEGO system to induce SMP-1 at a physiological level, we found that SMP-1 interacts with PLX-1 only in trans upon contact between vulval precursor cells. In contrast, when overexpressed, SMP-1 exhibits the ability to cis-interact with PLX-1 on a single cell. These results indicate that mosaic analysis with IR-LEGO, especially when combined with an in vivo recombination system, efficiently complements conventional methods.

Patients with severe hypophosphatasia (HPP) develop osteogenic impairment with extremely low alkaline phosphatase (ALP) activity, resulting in a fatal course during infancy. Mesenchymal stem cells (MSCs) differentiate into various mesenchymal lineages, including bone and cartilage. The efficacy of allogeneic hematopoietic stem cell transplantation for congenital skeletal and storage disorders is limited, and therefore we focused on MSCs for the treatment of HPP. To determine the effect of MSCs on osteogenesis, we performed multiple infusions of ex vivo expanded allogeneic MSCs for two patients with severe HPP who had undergone bone marrow transplantation (BMT) from asymptomatic relatives harboring the heterozygous mutation. There were improvements in not only bone mineralization but also muscle mass, respiratory function, and mental development, resulting in the patients being alive at the age of 3. After the infusion of MSCs, chimerism analysis of the mesenchymal cell fraction isolated from bone marrow in the patients demonstrated that donor-derived DNA sequences existed. Adverse events of BMT were tolerated, whereas those of MSC infusion did not occur. However, restoration of ALP activity was limited, and normal bony architecture could not be achieved. Our data suggest that multiple MSC infusions, following BMT, were effective and brought about clinical benefits for patients with lethal HPP. Allogeneic MSC-based therapy would be useful for patients with other congenital bone diseases and tissue disorders if the curative strategy to restore clinically normal features, including bony architecture, can be established.

The mechanical features of individual cells have been regarded as unique indicators of their states, which could constantly change in accordance with cellular events and diseases. Particularly, cancer progression was characterized by the disruption and/or reorganization of actin filaments causing mechanical changes. Thus, mechanical characterization of cells could become an effective cytotechnological approach for early detection of cancer. To develop mechanical cytotechnology, it would be necessary to clarify the mechanical properties in various cell adhesion states. In this study, we investigated the surface mechanical behavior of cancer and normal cells in the adherent and suspended states using atomic force microscopy. Adherent normal stromal cells showed high surface stiffness due to developed actin cap structures on their apical surface, whereas cancer cells did not have developed filamentous actin structures, and their surface stiffness was low. Upon cell detachment from the substrate, filamentous actin structures of adherent normal stromal cells reorganized to the cortical region and their surface stiffness decreased consequently however, the stiffness of suspended normal cells remained higher than that of cancer cells. These suspended state actin structures were similar, regardless of the cell type. Furthermore, the mechanical responses of the cancer and normal stromal cells to perturbation of the actin cytoskeleton were different, suggesting distinct regulatory mechanisms for actin cytoskeleton in cancer and normal cells in both adherent and suspended states. Therefore, cancer cells possess specific mechanical and actin cytoskeleton features different from normal stromal cells.

Bone marrow (BM) transplantation (BMT) is one of the treatment strategies for congenital metabolic disease, but leukemia secondary to intensive cytoreductive treatment is a major concern. Besides BM cells, mesenchymal stem cells (MSC) are also used for transplantation. An 8-month-old girl with hypophosphatasia underwent transplantation of haploidentical BM cells followed by two transplants of MSC obtained from her father to facilitate osteogenesis. Fludarabine(Flu)/cyclophosphamide (CPA)/anti-thymocyte globulin were used for myeloablative conditioning, but the patient developed therapy-related leukemia harboring t(9;22)(q34;q11.2); minor BCR-ABL (t-leukemia with Ph) at the age of 32 months. At the age of 40 months she underwent a second BM and third MSC transplant from the same donor. Thereafter, she achieved complete histological and molecular remission. The present case suggests that the combination of cytotoxic agents (Flu/CPA) and MSC led to t-leukemia with Ph as a consequence of chromosome instability and suppression of host anti-tumor immunity.

Feline McDonough Sarcoma (FMS)-like tyrosine kinase 4 (FLT4) is a marker for lymphatic vessels and some high endothelial venules in human adult tissues. We generated a transgenic medaka fish in which the lymphatic vessels and some blood vessels are visible in vivo by transferring the promoter of medaka flt4 driving the expression of enhanced green fluorescent protein (EGFP) using a see-through medaka line. To do this, we identified and cloned medaka flt4 and generated a construct in which the promoter was the 4-kb region upstream of the translation initiation site. The fluorescent signal of EGFP could be observed with little background, and the expression pattern correlated well with that of flt4 determined by whole-mount RNA in situ hybridization. Because a see-through medaka line is transparent until adult, the model is useful for visualizing the lymphatic vessels not only in embryo and fry but also in adult. This model will be a useful tool for analyzing lymphatic development.

G protein-coupled receptors are critical regulators of diverse developmental processes such as oocyte maturation, fertilization, gastrulation, and organogenesis. To further study the molecular mechanisms underlying these processes, we cloned and characterized the orphan leucine-rich repeat-containing G protein-coupled receptor 6 (LGR6), a stem cell marker in mammalian hair follicles, in medaka fish, Oryzias latipes. To examine the expression pattern of lgr6, we performed whole-mount in situ hybridization (WISH) during embryogenesis. The expression of lgr6 was first detected as a band in the anterior part of the posterior brain vesicle in 0.5-1 day post fertilization (dpf) embryos. This band disappeared by 2 dpf, but new signals appeared in the otic vesicles bordering the original band and also detected in the nasal placode and posterior lateral line primordia. At later stages (3-5 dpf), lgr6 was widely expressed in the brain, otic vesicle, neuromasts, root of the pectoral fin, cranial cartilage, and gut. Then, we conducted more detailed expression analysis of lgr6 in adult gut using WISH and immunohistochemical staining. Lgr6-positive cells were detected in the crypt-like proliferative zone and in parts of the villus. We also performed RT-PCR of mRNAs from different tissues. The lgr6 mRNA was found highest in the kidney and gill. The transcript was also present in the brain, heart, liver, spleen, intestine, skeletal muscle, testis, and ovary, similar to that of mammalian LGR6. These results suggest that medaka lgr6 plays an important role in organ development during embryogenesis and serves as a good molecular marker for future studies of postembryonic organ-specific development in mammals.

The Col2a1 gene is expressed in notochord, otic vesicle, cartilaginous tissue and the anlage of endochondral bone during development in higher vertebrates. Type II collagen, a homotrimeric product of the Col2a1 gene, functions as a key regulatory protein for cartilage development and endochondral ossification. In medaka and zebrafish, a single homolog of the col2a1 gene has been identified. However, it is necessary to note that many genes are duplicated in teleost fishes. To clarify function of col2a1 genes in teleost fishes and to further understand the process of cartilage development and endochondral ossification, we cloned and mapped the gene loci of two col2a1 orthologs in medaka. The proteins encoded by both medaka col2a1a and col2a1b genes were highly conserved (85.3% and 82.6%) relative to human COL2A1, but synteny was not observed. We also examined the expression patterns of col2a1a and col2a1b during embryonic development. Whole-mount insitu hybridization data suggests that expression patterns of both medaka co2a1a and col2a1b genes are similar to that of zebrafish co2a1 in the early embryonic stages. In medaka, the two col2a1 genes show a closely correlated pattern of spatial and temporal expression. In late embryonic stages, however, there were differences in both expression patterns in the pectoral fin. This study is the first report of two homologs of col2a1 in teleosts and also the first examination of col2a1a and col2a1b expression patterns in this group.

Mesenchymal stromal cells (MSCs) derived from human bone marrow have capability to differentiate into cells of mesenchymal lineage (7). Especially, the differentiation capability towards osteogenic cells is very well known. We have already used the patient's MSCs for the treatments of osteoarthritis (8), bone necrosis (2) and bone tumor cases (5). In most cases, the MSCs were culture- expanded from patient's fresh bone marrow cells, and then combined with porous ceramics. The MSCs/ceramics composites were further cultured in a medium containing dexamethasone to promote osteogenic differentiation of the MSCs. In this culture condition, we could detect bone forming osteoblasts together with mineralized bone matrix on the ceramics (7); therefore, we could fabricate cultured bone using patient's bone marrow and ceramics. However, the proliferation and differentiation capability of the MSCs are variable and many lose their capabilities after several passages. With the aim of conferring higher capability on human bone marrow MSCs, some of transcription factors could be introduced into the MSCs. This review paper demonstrates the importance of the transcription factors to promote the osteogenesis as well as proliferation capabilities of human MSCs.

The expression of four transcription factors (OCT3/4, SOX2, KLF4, and MYC) can reprogram mouse as well as human somatic cells to induced pluripotent stem (iPS) cells. We generated iPS cells from mesenchymal stromal cells (MSCs) derived from human third molars (wisdom teeth) by retroviral transduction of OCT3/4, SOX2, and KLF4 without MYC, which is considered as oncogene. Interestingly, some of the clonally expanded MSCs could be used for iPS cell generation with 30–100-fold higher efficiency when compared with that of other clonally expanded MSCs and human dermal fibroblasts. Global gene expression profiles demonstrated some up-regulated genes regarding DNA repair/histone conformational change in the efficient clones, suggesting that the processes of chromatin remodeling have important roles in the cascade of iPS cells generation. The generated iPS cells resembled human embryonic stem (ES) cells in many aspects, including morphology, ES marker expression, global gene expression, epigenetic states, and the ability to differentiate into the three germ layers in vitro and in vivo. Because human third molars are discarded as clinical waste, our data indicate that clonally expanded MSCs derived from human third molars are a valuable cell source for the generation of iPS cells.

Heat shock protein promoters (hsp promoters) are powerful tools for investigating gene functions, as the expression of targeted genes can be controlled simply by heating. However, there have been no reports of the utilization of an endogeneous medaka (Oryzias latipes) hsp promoter to induce exogenous gene expression in medaka. We identified and cloned a functional medaka hsp promoter (olphsp70.1) and verified its ability to act as an inducible promoter both in vitro and in vivo. The hsp promoter efficiently induced exogenous gene expression in cultured cells, developing embryos, and also in adult fishes. When used to control the expression of Venus, a variant of yellow fluorescent protein, in transgenic medaka, the hsp promoter was functional in all tissues except for the gonads of adults. These results indicate that the medaka hsp promoter can be a powerful tool for inducing exogenous gene expression and investigating gene functions both in vitro and in vivo in medaka.

Heat shock promoters are powerful tools for the precise control of exogenous gene induction in living organisms. In addition to the temporal control of gene expression, the analysis of gene function can also require spatial restriction. Recently, we reported a new method for in vivo, single-cell gene induction using an infrared laser-evoked gene operator (IR-LEGO) system in living nematodes (Caenorhabditis elegans). It was demonstrated that infrared (IR) irradiation could induce gene expression in single cells without incurring cellular damage. Here, we report the application of IR-LEGO to the small fish, medaka (Japanese killifish; Oryzias latipes) and zebrafish (Danio rerio), and a higher plant (Arabidopsis thaliana). Using easily observable reporter genes, we successfully induced gene expression in various tissues in these living organisms. IR-LEGO has the potential to be a useful tool in extensive research fields for cell/tissue marking or targeted gene expression in local tissues of small fish and plants.

Methods for turning on/off gene expression at any desired time and place in vivo would be useful for analyzing various biological processes. We have developed a novel microscopic system utilizing an infrared laser, IR-LEGO (infrared-laser evoked gene operator), which is designed to deposit heat locally in living organisms. We have shown that IR-LEGO enables us to induce the heat shock response efficiently in targeted single cells of C. elegans worms, thereby driving expression of a transgene under the control of a heat shock promoter. By using IR-LEGO we attempted to rescue several mutant phenotypes of worms at the single-cell level. Diverse cell behaviors including differentiation and migration of target cells can be manipulated by gene induction mediated by IR-LEGO. Our results showed that IR-LEGO can be used to manipulate cell-autonomous as well as cell-nonautonomous behaviors, further confirming that irradiation using IR-LEGO has no harmful effects on the targets. Thus, IR-LEGO serves as valuable tools for manipulating biological processes in living organisms.

Egr1 and Egr3 are zinc finger-type transcription factors and known as synaptic activity-inducible immediate-early genes. Egr1 also plays important roles in many aspects of vertebrate development. Egr3 is known as the gene that is related to biological rhythm and muscular development, but its behavior in the central nervous system during development is not clear. We cloned the cDNA of the egr1 and egr3 orthologs in medaka, and examined their expression patterns during embryonic development using whole-mount in situ hybridization. Medaka egr3 was the first cloned egr3 gene in fish. The expression of egr1 mRNA was first detected at 1day post-fertilization (dpf). It was expressed in the whole embryonic body. At 3dpf, the egr1 mRNA was strongly expressed in the telencephalon, diencephalon, hypothalamus, optic tectum, dorsal medulla oblongata, retina, heart, pharynx, and pectoral fin. The expression of egr3 mRNA was first detected at 3dpf. It was expressed in the telencephalon, hypothalamus, optic tectum, and pharynx. By sectioning the whole-mount specimens, expression of both the egr1 and egr3 mRNAs were observed in the telencephalon, hypothalamus, and optic tectum. However, the positions at which the genes were expressed were different.

The transparent bodies of see-through medaka fish has led to their use as models for in vivo cell and tissue imaging. However, these fish may also prove useful as models for pathological processes. Accumulating reports show that pathology in fish is similar to that in mammals, including humans. In this study, pathological characterization, comparison of data from rodents and in vivo pharmacological analyses of isoproterenol (Iso)-treated fish were performed. Larval fish showed cardiac hypertrophy-like changes after exposure to10 microg/ml Iso for more than one day. Hearts of Iso-treated fish had a larger size and a thicker wall, especially in the ventricle, compared with normal hearts. Several messenger RNA levels dose-dependently increased in Iso-treated fish in a manner similar to that in rodents. Symptoms that accompany mammalian cardiac hypertrophy, such as congestion, were also observed. Propranolol (Pro), a non-selective beta-adrenoceptor blocker (AR), significantly protected the increase in heart rate and volume and other simultaneous symptoms induced by Iso exposure. Athletic capability, measured by optomotor response, showed a dose-dependent decrease after Iso treatment, but was protected by Pro. In contrast, metoprolol (Met) and butoxamine (Btx), selective beta1- and beta2-AR blockers, had little effect in this analysis. These results show that Iso-treated fish develop pathologies analogous to those found in mammalian systems, suggesting that medaka fish can be used for investigation of cardiac hypertrophy; however, drug affinity differences should be considered between species.

Medaka is a small Asian freshwater teleost and has been an excellent model for fertilization studies for more than 50 years. Therefore, experimental procedures for in vitro fertilization (IVF) and cryopreservation of sperm are well established. In contrast, since the eggs or early embryos can not be cryopreserved, many females are killed to obtain unfertilized eggs for IVF. Recent progress in genomics is establishing medaka as a new model animal in functional genomics, and numerous mutant and transgenic strains have been established and stored as frozen sperm. Accumulated preserved resources require a simple and reliable recovery method for IVF. In this paper, we describe a method for obtaining a large number of unfertilized eggs without killing females, using sterile interspecific hybrids between Oryzias latipes and O. curvinotus. However, there is no report about the normality of offspring that were obtained by IVF using unfertilized eggs spawned in mating with the sterile hybrid male. In this paper, we have confirmed the reliability of the method regarding the influences on the next generation and also assessed conditions for efficient collection of unfertilized eggs. The method would be useful not only for fertilization studies but also for keeping transgenics and mutants, including a mutant library for a reverse genetic approach.

Xeroderma pigmentosum group A (XP-A) is a genetic disorder in which there is an abnormality in nucleotide excision repair that causes hypersensitivity to sunlight and multiple skin cancers. The development of central and peripheral neurological disorders not correlated to ultraviolet light exposure is associated with XP-A. The genes responsible for XP-A have been identified and a XPA knockout mouse has been generated. These knockout mice exhibit cutaneous symptoms, but they do not show neurological disorders. The mechanism of pathogenesis of neurological disorders is still unclear and therapeutic methods have not been established. Therefore, we generated XP-A patient-derived human induced pluripotent stem cells (XPA-iPSCs) to produce in vitro models of neurological disorders. We obtained iPSC lines from fibroblasts of two patients carrying different mutations. Drugs screened using XPA-iPSC lines can be helpful for treating XP-A patients in Japan. Additionally, we revealed that these iPSCs have the potential to differentiate into neural lineage cells, including dopaminergic neurons, which decrease in XP-A patients. Our results indicate that expression of the normal XPA gene without mutations is not required for generation of iPSCs and differentiation of iPSCs into neural lineage cells. XPA-iPSCs may become useful models that clarify our understanding of neurological pathogenesis and help to establish therapeutic methods.

This research was originally published in the Journal of Biological Chemistry. Tadato Ban, Kenichi Morigaki, Hisashi Yagi, Takashi Kawasaki, Atsuko Kobayashi, Shunsuke Yuba, Hironobu Naiki and Yuji Goto. Real-time and Single Fibril Observation of the Formation of Amyloid β Spherulitic Structures. J. Biol. Chem. 2006; 281, 33677–33683. © the American Society for Biochemistry and Molecular Biology, In Alzheimer disease, amyloid β, a 39-43-residue peptide produced by cleavage from a large amyloid precursor protein, undergoes conformational change to form amyloid fibrils and deposits as senile amyloid plaques in the extracellular cerebral cortices of the brain. However, the mechanism of how the intrinsically linear amyloid fibrils form spherical senile plaques is unknown. With total internal reflection fluorescence microscopy combined with the use of thioflavin T, an amyloid-specific fluorescence dye, we succeeded in observing the formation of the senile plaque-like spherulitic structures with diameters of around 15 μm on the chemically modified quartz surface. Real-time observation at a single fibrillar level revealed that, in the absence of tight contact with the surface, the cooperative and radial growth of amyloid fibrils from the core leads to a huge spherulitic structure. The results suggest the underlying physicochemical mechanism of senile plaque formation, essential for obtaining insight into prevention of Alzheimer disease.

Non-neuronal acetylcholine (ACh) is predicted to function as a local cell signaling molecule. However, the physiological significance of the synthesis of non-neuronal ACh in the intestine remains unclear. Here, experiments using crypt–villus organoids that lack nerve and immune cells in culture led us to suggest that endogenous ACh is synthesized in the intestinal epithelium to evoke growth and differentiation of the organoids through activation of muscarinic ACh receptors (mAChRs). The extracts of the cultured organoids showed a noticeable capacity for ACh synthesis that was sensitive to a potent inhibitor of choline acetyltransferase. Imaging MS revealed endogenous ACh localized in the epithelial layer in mouse small intestinal epithelium in vivo, suggesting that there are non-neuronal resources of ACh. Treatment of organoids with carbachol downregulated the growth of organoids and the expression of marker genes for epithelial cells. On the other hand, antagonists for mAChRs enhanced the growth and differentiation of organoids, indicating the involvement of mAChRs in regulating the proliferation and differentiation of Lgr5-positive stem cells. Collectively, our data provide evidence that endogenous ACh released from intestinal epithelium maintains homeostasis of intestinal epithelial cell growth and differentiation via mAChRs in mice.

Social familiarity affects mating preference among various vertebrates. Here, we show that visual contact of a potential mating partner before mating (visual familiarization) enhances female preference for the familiarized male, but not for an unfamiliarized male, in medaka fish. Terminal-nerve gonadotropin-releasing hormone 3 (TN-GnRH3) neurons, an extrahypothalamic neuromodulatory system, function as a gate for activating mating preferences based on familiarity. Basal levels of TN-GnRH3 neuronal activity suppress female receptivity for any male (default mode). Visual familiarization facilitates TN-GnRH3 neuron activity (preference mode), which correlates with female preference for the familiarized male. GnRH3 peptides, which are synthesized specifically in TN-GnRH3 neurons, are required for the mode-switching via self-facilitation. Our study demonstrates the central neural mechanisms underlying the regulation of medaka female mating preference based on visual social familiarity.

Background Cryptochromes (CRY), members of the DNA photolyase/cryptochrome protein family, regulate the circadian clock in animals and plants. Two types of animal CRYs are known, mammalian CRY and Drosophila CRY. Both CRYs participate in the regulation of circadian rhythm, but they have different light dependencies for their reactions and have different effects on the negative feedback loop which generates a circadian oscillation of gene expression. Mammalian CRYs act as a potent inhibitor of transcriptional activator whose reactions do not depend on light, but Drosophila CRY functions as a light-dependent suppressor of transcriptional inhibitor. Results We cloned seven zebrafish genes that carry members of the DNA photolyase/cryptochrome protein family; one (6-4)photolyase and six cry genes. A sequence analysis and determination of their in vitro functions showed that these zebrafish cry genes constitute two groups. One has a high sequence similarity to mammalian cry genes and inhibits CLOCK:BMAL1 mediated transcription. The other, which has a higher sequence similarity to the Drosophila cry gene rather than the mammalian cry genes, does not carry transcription inhibitor activity. The expressions of these cry genes oscillate in a circadian manner, but their patterns differ. Conclusions These findings suggest that functionally diverse cry genes are present in zebrafish and each gene has different role in the molecular clock.

Objective— Infrared laser–evoked gene operator is a new microscopic method optimized to heat cells in living organisms without causing photochemical damage. By combining the promoter system for the heat shock response, infrared laser–evoked gene operator enables laser-mediated gene induction in targeted cells. We applied this method to the vascular system in zebrafish embryos and demonstrated its usability to investigate mechanisms of vascular morphogenesis in vivo. Approach and Results— We used double-transgenic zebrafish with fli1:nEGFP to identify the endothelial cells, and with hsp:mCherry to carry out single-cell labeling. Optimizing the irradiation conditions, we finally succeeded in inducing the expression of the mCherry gene in single targeted endothelial cells, at a maximum efficiency rate of 60%. In addition, we indicated that this system could be used for laser ablation under certain conditions. To evaluate infrared laser–evoked gene operator, we applied this system to the endothelial cells of the first intersegmental arteries, and captured images of the connection between the vascular systems of the brain and spinal cord. Conclusions— Our results suggest that the infrared laser–evoked gene operator system will contribute to the elucidation of the mechanisms underlying vascular morphogenesis by controlling spatiotemporal gene activation in single endothelial cells, by labeling or deleting individual vessels in living embryos.

Xeroderma pigmentosum (XP) is an autosomal recessive disorder characterized by a high frequency of skin cancer on sun-exposed areas, and neurological complications. XP has a defect in the early step(s) of nucleotide-excision repair (NER) and consists of eight different genetic complementation groups (groups A-G and a variant). We established XPA (group-A XP) gene-deficient mice by gene targeting of mouse embryonic stem (ES) cells. The XPA-deficient mice showed neither obvious physical abnormalities nor pathological alterations, but were defective in NER and highly susceptible to ultraviolet-B- or 9,10-dimethyl-1,2-benz[a]anthracene-induced skin carcinogenesis. These findings provide in vivo evidence that the XPA protein protects mice from carcinogenesis initiated by ultraviolet or chemical carcinogen. The XPA-deficient mice may provide a good in vivo model to study the high incidence of skin carcinogenesis in group A XP patients.

Bone marrow (BM) transplantation (BMT) is one of the treatment strategies for congenital metabolic disease, but leukemia secondary to intensive cytoreductive treatment is a major concern. Besides BM cells, mesenchymal stem cells (MSC) are also used for transplantation. An 8-month-old girl with hypophosphatasia underwent transplantation of haploidentical BM cells followed by two transplants of MSC obtained from her father to facilitate osteogenesis. Fludarabine(Flu)/cyclophosphamide (CPA)/anti-thymocyte globulin were used for myeloablative conditioning, but the patient developed therapy-related leukemia harboring t(9;22)(q34;q11.2); minor BCR-ABL (t-leukemia with Ph) at the age of 32 months. At the age of 40 months she underwent a second BM and third MSC transplant from the same donor. Thereafter, she achieved complete histological and molecular remission. The present case suggests that the combination of cytotoxic agents (Flu/CPA) and MSC led to t-leukemia with Ph as a consequence of chromosome instability and suppression of host anti-tumor immunity.

Intracellular transport is spatiotemporally controlled by microtubule-dependent motor proteins, including kinesins. In order to elucidate the mechanisms controlling kinesin expression, it is important to analyze their genomic regulatory regions. In this study, we cloned the neuronal tissue-specific kinesin in medaka fish and generated transgenic fish which mimic endogenous neuronal kinesin expression in order to elucidate the mechanisms which regulate kinesin expression. Searches for medaka neuronal orthologues by RT-PCR identified a candidate gene expressed only in neuronal tissues. Using BAC clones, we determined the cDNA sequence and the gene structure of the candidate neuronal kinesin. Evolutionary analysis indicated that the candidate gene encoded medaka KIF5Aa. The endogenous medaka orthologue was found to be expressed only in the nervous system, including the brain and spinal cord, while expression of KIF5Ab was not exclusive to neuronal tissues. Transgenic (Tg) medaka that expressed EGFP under the control of the 6.9 kbp 5' and 1.9kbp 3' flanking regions of the KIF5Aa gene showed characteristic expression throughout the nervous system, including the brain, spinal cord, olfactory pit, eye and cranial nerve. Immunohistological analysis showed that EGFP expression in Tg fish co-localized with expression of HuC/D, a neuronal marker. These results demonstrate that the 6.9 kbp 5' and 1.9 kbp 3' flanking regions of medaka KIF5Aa have neuronal-specific promoter activity mimicking endogenous expression of medaka KIF5Ab. This transgenic fish strain will be useful for further functional analysis of the effects of these regulatory regions on gene expression.

Generation of induced pluripotent stem (iPS) cells have the potential for investigation of molecular mechanisms of disease, understanding the development of human tissues, and clinical applications. Although it was reported that various kinds of human somatic cells reprogrammed into iPS cells, most of them showed low reprogramming efficiency. Previously, we reported that clonally-expanded mesenchymal stromal/stem cells (MSCs) derived from tooth germs of human third molars efficiently reprogrammed into iPS cells by retroviral transduction of OCT3/4, SOX2, and KLF4 without c-MYC. Our data indicated that human third molars, which usually discarded as clinical wastes, are a valuable cell source for generation of iPS cells. Here, we describe detailed methods of the MSCs preparation and iPS cells generation from the MSCs.

Mesenchymal stem cells (MSCs) have been extensively investigated for their applications in regenerative medicine. Successful use of MSCs in cell-based therapies will rely on the ability to effectively identify their properties and functions with a relatively non-destructive methodology. In this study, we measured the surface stiffness and thickness of rat MSCs with atomic force microscopy and clarified their relation at a single-cell level. The role of the perinuclear actin cap in regulating the thickness, stiffness, and proliferative activity of these cells was also determined by using several actin cytoskeleton-modifying reagents. This study has helped elucidate a possible link between the physical properties and the physiological function of the MSCs, and the corresponding regulatory role of the actin cytoskeleton.

Bone marrow-derived mesenchymal stem cells (BMSCs) and adipose tissue-derived mesenchymal stem cells (AMSCs) have been used clinically for tissue regeneration; however, their proliferation/differentiation potentials are limited. Recently, induced pluripotent stem cells (iPSCs), known to have nearly unlimited potential to proliferate and differentiate into cells of all three germ layers, have gained wide interest in regenerative medicine. Here, we generated iPSCs from frozen-stocked AMSCs and BMSCs and examined their biological characteristics by comparative analyses. Although the iPSCs were more challenging to generate from the BMSCs than the AMSCs, both iPSC populations expressed pluripotent markers, such as stage-specific embryonic antigen (SSEA)-3, SSEA-4, tumour-related antigens (TRAs) TRA-1-60 and TRA-1-81, OCT3/4 and NANOG. Furthermore, both cell populations differentiated well into three germ layer-derived cells, both in vitro and in vivo. These results indicate that iPSCs derived from frozen AMSCs/BMSCs exhibit equally acceptable iPSC characteristics and have potential in clinical applications as an alternative source of autogenous stem cells.

Heat shock promoters are powerful tools for the precise control of exogenous gene induction in living organisms. In addition to the temporal control of gene expression, the analysis of gene function can also require spatial restriction. Recently, we reported a new method for in vivo, single-cell gene induction using an infrared laser-evoked gene operator (IR-LEGO) system in living nematodes (Caenorhabditis elegans). It was demonstrated that infrared (IR) irradiation could induce gene expression in single cells without incurring cellular damage. Here, we report the application of IR-LEGO to the small fish, medaka (Japanese killifish; Oryzias latipes) and zebrafish (Danio rerio), and a higher plant (Arabidopsis thaliana). Using easily observable reporter genes, we successfully induced gene expression in various tissues in these living organisms. IR-LEGO has the potential to be a useful tool in extensive research fields for cell/tissue marking or targeted gene expression in local tissues of small fish and plants.

Background Pmp22, a member of the junction protein family Claudin/EMP/PMP22, plays an important role in myelin formation. Increase of pmp22 transcription causes peripheral neuropathy, Charcot-Marie-Tooth disease type1A (CMT1A). The pathophysiological phenotype of CMT1A is aberrant axonal myelination which induces a reduction in nerve conduction velocity (NCV). Several CMT1A model rodents have been established by overexpressing pmp22. Thus, it is thought that pmp22 expression must be tightly regulated for correct myelin formation in mammals. Interestingly, the myelin sheath is also present in other jawed vertebrates. The purpose of this study is to analyze the evolutionary conservation of the association between pmp22 transcription level and vertebrate myelin formation, and to find the conserved non-coding sequences for pmp22 regulation by comparative genomics analyses between jawed fishes and mammals. Results A transgenic pmp22 over-expression medaka fish line was established. The transgenic fish had approximately one fifth the peripheral NCV values of controls, and aberrant myelination of transgenic fish in the peripheral nerve system (PNS) was observed. We successfully confirmed that medaka fish pmp22 has the same exon-intron structure as mammals, and identified some known conserved regulatory motifs. Furthermore, we found novel conserved sequences in the first intron and 3'UTR. Conclusion Medaka fish undergo abnormalities in the PNS when pmp22 transcription increases. This result indicates that an adequate pmp22 transcription level is necessary for correct myelination of jawed vertebrates. Comparison of pmp22 orthologs between distantly related species identifies evolutionary conserved sequences that contribute to precise regulation of pmp22 expression.

Prox1 is a prospero-related homeobox gene. Prox1 is expressed in various internal organs and is related to those differentiations. Small fishes such as the zebrafish and the medaka are useful model animals in the clarification of the mechanism of development. The zebrafish prox1 is also identified, and it contributes to clarifying the function of prox1. However, it is necessary to note that many genes are duplicated in teleost fishes. In this study, we identified the orthologs of the mammalian prox1 gene in the medaka. The gene was also duplicated in the medaka, and we named it prox1a and prox1b. In silico analysis from the perspective of synteny indicated that medaka prox1a was similar to the prox1 gene of other vertebrates. Medaka prox1a was expressed in all internal organs that we have examined by RT-PCR. In contrast, medaka prox1b expression was limited to the brain, heart, liver, kidney, thymus, gill, testis, and ovary. This suggests that the two prox1 genes do not have a complementary relationship. In addition, we examined their expression patterns during embryonic development using whole-mount in situ hybridization. The expression pattern of prox1a showed a pattern similar to that of zebrafish prox1. In contrast, medaka prox1b was expressed asymmetrically in part of the central nervous system, especially strongly in the right side of the habenula.

Methods for turning on and off gene expression at the experimentalist's discretion would be useful for analyzing various biological processes. They would also serve as valuable tools for manipulating biological processes in living organisms. We have been developing a novel microscopic system utilizing an infraredinfrared laser laser, IR-LEGO (infrared-laser evoked gene operator), which is designed to deposit heat locally in living organisms. We have shown that IR-LEGO enables us to induce the heat shock response efficiently in targeted single cells of C. elegans worms, thereby driving expression of a transgene under the control of a heat shock promoter. Compared with the Coumarin dye laser, which had been used for targeted gene induction mediated by the heat shock response, we expect that the IR-laser can heat biological tissues much more efficiently and is less harmful to cells. Combination of IR-LEGO with other techniques for gene manipulation, such as the in vivo recombination and RNA interference, would further widen its scope of application.

Though DNA polymerase I (poll) of Escherichia (E.) coli is understood to play a role in repair synthesis of excision repair, it is still obscure whether DNA polymerase beta (pol beta) plays a similar role in eukaryotic cells. To estimate the role of pol beta in excision repair processes, we inserted the rat pol beta gene into several mutant E. coli defective in a diverse set of enzymatic activities of poll. UV resistance was seen only when the 5'----3' exonuclease (exo) activity of poll molecules remained. Therefore it is suggested that 5'----3' exo activity as well as pol beta activity are essential for repair synthesis of excision repair in eukaryotic cells.

Medaka is a small Asian freshwater teleost and has been an excellent model for fertilization studies for more than 50 years. Therefore, experimental procedures for in vitro fertilization (IVF) and cryopreservation of sperm are well established. In contrast, since the eggs or early embryos can not be cryopreserved, many females are killed to obtain unfertilized eggs for IVF. Recent progress in genomics is establishing medaka as a new model animal in functional genomics, and numerous mutant and transgenic strains have been established and stored as frozen sperm. Accumulated preserved resources require a simple and reliable recovery method for IVF. In this paper, we describe a method for obtaining a large number of unfertilized eggs without killing females, using sterile interspecific hybrids between Oryzias latipes and O. curvinotus. However, there is no report about the normality of offspring that were obtained by IVF using unfertilized eggs spawned in mating with the sterile hybrid male. In this paper, we have confirmed the reliability of the method regarding the influences on the next generation and also assessed conditions for efficient collection of unfertilized eggs. The method would be useful not only for fertilization studies but also for keeping transgenics and mutants, including a mutant library for a reverse genetic approach.

Ectopic expression via transgene is powerful means for functional analysis of genes of multicellular organisms in vivo. Use of tissue-specific promoters for ectopic expression is limited by their inherent properties to drive gene expression in a restricted temporal-spatial expression pattern. We have developed a novel microscopic system utilizing an infrared laser, IR-LEGO (infrared-laser evoked gene operator) in order to induce heat shock response efficiently in targeted single cells of living organisms, thereby driving expression of a transgene under the control of a heat shock promoter. The system utilizes IR light because we expect that the IR laser can heat biological tissues much more efficiently and is less harmful to cells compared with a Coumarin dye laser, which was used in previous studies. When applied to living nematode C. elegans worms under appropriate conditions, IR-LEGO induced gene expression effectively and reproducibly in targeted single cells. Heat shock-induced cells underwent subsequent development normally, suggesting that the IR-LEGO-mediated heat shock induction does not cause significant cell damages. The system would enable us to induce gene expression in temporally and spatially regulated manners in any organisms, for which transgenic technology is available.

Usually, tissue specific promoters are used to examine the function of a gene of interest in vivo in transgenic lines of model organisms such as C. elegans and mice, complementing the genetic analysis with mosaic organisms. However, use of tissue specific promoters is limited by their inherent properties to drive gene expression in a restricted temporal-spatial expression pattern. It is desirable to develop techniques for regulating gene expression in a controllable way both temporally and spatially at single cell resolution. Once such techniques have been established in model organisms, they would serve as a basis for developing techniques to manipulate cellular behavior in other organisms including human. In this paper, we will first summarize previous attempts to drive gene expression at a desired time and space by using inducible promoters, in particular heat shock promoters. Then, we will examine problems encountered in the previous attempts, and report our new approach to circumvent them.

Importin alpha1 (also referred to as NPI1 or importin alphaS1) gene encodes a member of the cytosolic receptor protein superfamily that recognizes classical monopartite and bipartite basic type nuclear localization signals and mediates nuclear protein import via an importin beta-dependent pathway. Here we report on the organization of the importin alpha1 locus in the mouse genome. The gene is approximately 40 kb in length from the translation initiation codon to the poly(A) additional site. The translated region of the gene is comprised of 13 coding exons and the exon-intron boundaries conform to the GT/AG rule. Importin alpha1 was mapped to a middle region of mouse chromosome 16 by fluorescence in situ hybridization analysis. Moreover, it was found by reverse transcriptase polymerase chain reaction analysis that importin alpha1 is widely expressed in various tissues in adult mice and at various stages during embyogenesis. This study is the first example that provides detailed genomic information on nuclear transport factors such as importins and exportins and provides a basis for further studies such as the generation of mutants in mice for purposes of investigating the role of importin alpha1 in development and differentiation.

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others.

The process of active nuclear protein transport is mediated by the nuclear localization signal (NLS). An NLS-containing karyophile forms a stable complex, termed the nuclear pore-targeting complex, to target nuclear pores. The alpha-subunit of the complex (importin-alpha) binds to the NLS and the beta-subunit (importin-beta) carries the alpha-subunit, bound to the NLS substrate, into the nucleus. To date, five mouse alpha-subunits have been identified and classified into three subfamilies (alpha-P, alpha-Q, and alpha-S). The expression of these alpha-subunits and the beta-subunit in various adult mouse tissues was examined by immunoblotting and immunohistochemistry using antibodies specific for each subfamily of the alpha-subunit or the beta-subunit. The beta-subunit was found to be ubiquitously expressed, whereas each subfamily of the alpha-subunit showed a unique expression pattern in various tissues, especially in brain and testis. In brain, the expression of alpha-P was not observed, whereas alpha-S was significantly expressed in Purkinje cells, and pyramidal cells of the hippocampus and cerebral cortex. In testis, alpha-P was expressed predominantly in primary spermatocytes, whereas alpha-Q was found mainly in Leydig cells. Expression of alpha-S was detected in almost all cells in convoluted seminiferous tubules and Leydig cells to a similar extent. These results suggest that nuclear protein import may be controlled in a tissue-specific manner by alpha-subunit family proteins.