Takami Takizawa

Human Villous Trophoblasts Express and Secrete Placenta-Specific MicroRNAs into Maternal Circulation via Exosomes

In this study, we performed small RNA library sequencing using human placental tissues to identify placenta-specific miRNAs. We also tested the hypothesis that human chorionic villi could secrete miRNAs extracellularly via exosomes, which in turn enter into maternal circulation. By small RNA library sequencing, most placenta-specific miRNAs (e.g., MIR517A) were linked to a miRNA cluster on chromosome 19. The miRNA cluster genes were differentially expressed in placental development. Subsequent validation by real-time PCR and in situ hybridization revealed that villous trophoblasts express placenta-specific miRNAs. The analysis of small RNA libraries from the blood plasma showed that the placenta-specific miRNAs are abundant in the plasma of pregnant women. By real-time PCR, we confirmed the rapid clearance of the placenta-specific miRNAs from the plasma after delivery, indicating that such miRNAs enter into maternal circulation. By using the trophoblast cell line BeWo in culture, we demonstrated that miRNAs are indeed extracellularly released via exosomes. Taken together, our findings suggest that miRNAs are exported from the human placental syncytiotrophoblast into maternal circulation, where they could target maternal tissues. Finally, to address the biological functions of placenta-specific miRNAs, we performed a proteome analysis of BeWo cells transfected with MIR517A. Bioinformatic analysis suggests that this miRNA is possibly involved in tumor necrosis factor-mediated signaling. Our data provide important insights into miRNA biology of the human placenta.

MicroRNA (miRNA) cloning analysis reveals sex differences in miRNA expression profiles between adult mouse testis and ovary

MicroRNAs (miRNAs) are endogenous non-coding small RNAs that can regulate the expression of complementary mRNA targets. Identifying tissue-specific miRNAs is the first step toward understanding the biological functions of miRNAs, which include the regulation of tissue differentiation and the maintenance of tissue identity. In this study, we performed small RNA library sequencing in adult mouse testis and ovary to reveal their characteristic organ- and gender-specific profiles and to elucidate the characteristics of the miRNAs expressed in the reproductive system. We obtained 10,852 and 11 744 small RNA clones from mouse testis and ovary respectively (greater than 10,000 clones per organ), which included 6630 (159 genes) and 10,192 (154 genes) known miRNAs. A high level of efficiency of miRNA library sequencing was achieved: 61% (6630 miRNA clones/10,852 small RNA clones) and 87% (10,192/11,744) for adult mouse testis and ovary respectively. We obtained characteristic miRNA signatures in testis and ovary; 55 miRNAs were detected highly, exclusively, or predominantly in adult mouse testis and ovary, and discovered two novel miRNAs. Male-biased expression of miRNAs occurred on the X-chromosome. Our data provide important information on sex differences in miRNA expression that should facilitate studies of the reproductive organ-specific roles of miRNAs.

Hydroxysteroid (17-β) Dehydrogenase 1 Is Dysregulated by Mir-210 and Mir-518c That Are Aberrantly Expressed in Preeclamptic Placentas: A Novel Marker for Predicting Preeclampsia

In this study, to search for novel preeclampsia (PE) biomarkers, we focused on microRNA expression and function in the human placenta complicated with PE. By comprehensive analyses of microRNA expression, we identified 22 microRNAs significantly upregulated in preeclamptic placentas, 5 of which were predicted in silico to commonly target the mRNA encoding hydroxysteroid (17-&bgr;) dehydrogenase 1 (HSD17B1), a steroidogenetic enzyme expressed predominantly in the placenta. In vivo HSD17B1 expression, at both the mRNA and protein levels, was significantly decreased in preeclamptic placentas. Of these microRNAs, miR-210 and miR-518c were experimentally validated to target HSD17B1 by luciferase assay, real-time PCR, and ELISA. Furthermore, we found that plasma HSD17B1 protein levels in preeclamptic pregnant women reflected the decrease of its placental expression. Moreover, a prospective cohort study of plasma HSD17B1 revealed a significant reduction of plasma HSD17B1 levels in pregnant women at 20 to 23 and 27 to 30 weeks of gestation before PE onset compared with those with normal pregnancies. The sensitivities/specificities for predicting PE at 20 to 23 and 27 to 30 weeks of gestation were 0.75/0.67 (cutoff value=21.9 ng/mL) and 0.88/0.51 (cutoff value=30.5 ng/mL), and the odds ratios were 6.09 (95% CI: 2.35–15.77) and 7.83 (95% CI: 1.70–36.14), respectively. We conclude that HSD17B1 is dysregulated by miR-210 and miR-518c that are aberrantly expressed in preeclamptic placenta and that reducing plasma level of HSD17B1 precedes the onset of PE and is a potential prognostic factor for PE.

Development of ichthyosiform skin compensates for defective permeability barrier function in mice lacking transglutaminase 1

Transglutaminase 1 (TGase 1) is one of the genes implicated in autosomal recessive congenital ichthyosis. Skin from TGase 1(-/-) mice, which die as neonates, lacks the normal insoluble cornified envelope and has impaired barrier function. Characterization of in situ dye permeability and transepidermal water loss revealed defects in the development of the skin permeability barrier in TGase 1(-/-) mice. In the stratum corneum of the skin, tongue, and forestomach, intercellular lipid lamellae were disorganized, and the corneocyte lipid envelope and cornified envelope were lacking. Neonatal TGase 1(-/-) mouse skin was taut and erythrodermic, but transplanted TGase 1(-/-) mouse skin resembled that seen in severe ichthyosis, with epidermal hyperplasia and marked hyperkeratosis. Abnormalities in those barrier structures remained, but transepidermal water loss was improved to control levels in the ichthyosiform skin. From these results, we conclude that TGase 1 is essential to the assembly and organization of the barrier structures in stratified squamous epithelia. We suggest that the ichthyosiform skin phenotype in TGase 1 deficiency develops the massive hyperkeratosis as a physical compensation for the defective cutaneous permeability barrier required for survival in a terrestrial environment.

RT-PCR-based analysis of microRNA (miR-1 and -124) expression in mouse CNS.

More than 700 microRNAs (miRNAs) have been cloned, and the functions of these molecules in developmental timing, cell proliferation, and cancer have been investigated widely. MiRNAs are analyzed with Northern blot and sequential colony evaluation; however, reverse transcription-polymerase chain reaction (RT-PCR)-based miRNA assay remains to be developed. In this report, we describe improved real-time RT-PCR methods using specific or non-specific RT primer for the semi-quantitative analysis of miRNA expression. The use of the new methods in a model study revealed differential expression of miRNA-1 (miR-1) and miR-124 in mouse organs. Specifically, our methods revealed that miR-124 concentrations in the mouse central nervous system (CNS; cerebral cortex, cerebellum, and spinal cord) were more than 100 times those in other organs. By contrast, miR-1 expression in the CNS was 100-1000 times lower than that in skeletal muscle and heart. Furthermore, we revealed anatomically regional differences in miR-124 expression within the CNS: expression ratios versus the cerebral cortex were 60.7% for the cerebellum and 35.4% for the spinal cord. These results suggest that our RT-PCR-based methods would be a powerful tool for studies of miRNA expression that is associated with various neural events.

Ultrastructural localization of S100A3, a cysteine-rich, calcium binding protein, in human scalp hair shafts revealed by rapid-freezing immunocytochemistry.

We have characterized the subcellular distribution of S100A3, a cysteine-rich calcium binding protein, in human scalp hair shaft. This was accomplished using rapid-freezing immunocytochemistry, a technique that combines rapid-freezing, freeze-substitution fixation without chemical fixatives, and subsequent electron microscopic detection of immunocytochemical labeling. This technique preserves both the antigenicity and the ultrastructural integrity of fully keratinized tissues, which are highly unmanageable when prepared for immunoelectron microscopy. In the hair shaft, S100A3 was primarily identified in the endocuticle and was also present in the intermacrofibrillar matrix surrounding macrofibril bundles of intermediate filament keratins in cortex cells. Double immunolabeling of S100A3 and hair keratins revealed the in situ spatial relationship between them. In the endocuticle, S100A3 was present on the inner portion of the endocuticle adjacent to the cell membrane complex, whereas hair keratins were present on the outer portion. These results provide the first ultrastructural evidence that an S100 protein is localized in specific subcompartments in human hair cells.

Sexually Dimorphic Expression of the Novel Germ Cell Antigen TEX101 During Mouse Gonad Development

Abstract Prospermatogonia, or gonocytes, are the cells that differentiate from primordial germ cells to the first mature type of spermatogonia in the developing testis. Although prospermatogonia play a central role in this stage (i.e., prespermatogenesis), the details regarding their characterization have not been fully elucidated. Recently, we identified a novel mouse testicular germ cell-specific antigen, TES101 reactive protein (TES101RP), in the adult mouse testis. The protein TES101RP is also designated as protein TEX101. In the present study, we investigated the expression of TEX101 on germ cells in developing mouse gonads using histochemical techniques (i.e., immunohistochemistry, BrdU labeling, and TUNEL staining) and reverse transcription-polymerase chain reaction. TEX101 appeared on germ cells in both male and female gonads after the pregonadal period. In the testis, TEX101 was expressed constitutively on surviving prospermatogonia during prespermatogenesis. After the initiation of spermatogenesis, the prospermatogonia differentiated into spermatogonia. TEX101 expression disappeared from the spermatogonia, but reappeared on spermatocytes and spermatids. In the ovary, TEX101 was expressed on germ cells until the start of folliculogenesis; TEX101 was not detected on oocytes that were surrounded by follicular cells. These findings indicate that TEX101 is a specific marker for both male and female germ cells during gonadal development. Because the on and off switching of TEX101 expression in germ cells almost parallels the kinetics of gametogenesis, TEX101 may play an important physiological role in germ cell development.

Human Exosomal Placenta-Associated miR-517a-3p Modulates the Expression of PRKG1 mRNA in Jurkat Cells

ABSTRACT During pregnancy, human placenta-associated microRNAs (miRNAs) derived from the miRNA cluster in human chromosome 19 are expressed in villous trophoblasts and secreted into maternal circulation via exosomes; however, little is known about whether circulating placenta-associated miRNAs are transferred into maternal immune cells via exosomes, and modulate expression of target genes in the recipient cells. We employed an in vitro model of trophoblast-immune cell communication using BeWo cells (a human trophoblast cell line) and Jurkat cells (a human leukemic T-cell line) and investigated whether BeWo exosomal placenta-associated miRNAs can suppress expression of target genes in the recipient Jurkat cells. Using this system, we identified PRKG1 as a target gene of placenta-associated miRNA miR-517a-3p. Moreover, we demonstrated that BeWo exosomal miR-517a-3p was internalized into Jurkat cells and subsequently suppressed the expression of PRKG1 in recipient Jurkat cells. Furthermore, using peripheral blood natural killer (NK) cells in vivo, we confirmed that circulating miR-517a-3p was delivered into maternal NK cells as it was into Jurkat cells in vitro. Placenta-associated miR-517a-3p was incorporated into maternal NK cells in the third trimester, and it was rapidly cleared after delivery. Expression levels of miR-517a-3p and its target mRNA PRKG1 were inversely correlated in NK cells before and after delivery. These in vitro and in vivo results suggest that exosome-mediated transfer of placenta-associated miRNAs and subsequent modulation of their target genes occur in maternal NK cells. The present study provides novel insight into our understanding of placenta-maternal communication.

TEX101 is shed from the surface of sperm located in the caput epididymidis of the mouse

It is generally believed that cell-to-cell cross-talk and signal transduction are mediated by cell surface molecules that play diverse and important regulatory roles in spermatogenesis and fertilization. Recently, we identified a novel plasma membrane-associated protein, TES101-reactive protein (TES101RP, or TEX101), on mouse testicular germ cells. In this study, we investigate Tex101 mRNA expression in the adult mouse testis using in situ hybridization, and we examine the fate of TEX101 during sperm transport by immunohistochemical and Western blot analyses. Tex101 mRNA was expressed in a stage-specific manner in spermatocytes and in step 1-9 spermatids of the testis, but not in spermatogonia. Although the TEX101 protein remained on the cell surfaces of step 10-16 spermatids and testicular sperm, it was shed from epididymal sperm located in the caput epididymidis. The results of this study provide additional information on germ cell-specific TEX101 expression during spermatogenesis and post-testicular sperm maturation.

Glucose-6-phosphate dehydrogenase cytochemistry using a copper ferrocyanide method and its application to rapidly frozen cells

Abstract We describe an improved copper ferrocyanide-based method for cytochemical detection of glucose-6-phosphate dehydrogenase (G6PD), which was used to localize the enzyme within the ultrastructure of rat hepatocytes and adrenocortical cells. With this method, glutaraldehyde fixation and the addition of exogenous electron carriers (for example, phenazine methosulfate) to the cytochemical reaction medium were essential. Copper ferrocyanide reaction product showing the distribution of G6PD was readily recognized at the light microscopic level as Hatchett’s brown staining and at the electron microscopic level as electron-dense deposits. Within stained regions, enzyme cytochemical G6PD activity was found to be associated with ribosome-like structures. Because G6PD is a soluble, cytosolic enzyme, its displacement or extraction may occur during conventional fixation. We, therefore, combined a rapid-freezing technique with G6PD enzyme cytochemistry. The resultant rapid-freezing enzyme cytochemistry enabled us to show the subcellular distribution of G6PD in a more life-like state; the localization of G6PD in rapidly frozen cells was in substantial agreement with that in conventionally fixed cells.