Expression and trafficking of placental microRNAs at the feto-maternal interface.

During pregnancy, placental trophoblasts at the feto-maternal interface produce a broad repertoire of microRNA (miRNA) species. These species include miRNA from the primate-specific chromosome 19 miRNA cluster (C19MC), which is expressed nearly exclusively in the placenta. Trafficking of these miRNAs among the maternal, placental, and fetal compartments is unknown. To determine miRNA expression and trafficking patterns during pregnancy, we sequenced miRNAs in triads of human placenta and of maternal and fetal blood and found large subject-to-subject variability, with C19MC exhibiting compartment-specific expression. We therefore created humanized mice that transgenically express the entire 160-kb human C19MC locus or lentivirally express C19MC miRNA members selectively in the placenta. C19MC transgenic mice expressed a low level of C19MC miRNAs in diverse organs. When pregnant, female C19MC mice exhibited a strikingly elevated (>40-fold) expression of C19MC miRNA in the placenta, compared with other organs, that resembled C19MC miRNAs patterns in humans. Our mouse models showed that placental miRNA traffic primarily to the maternal circulation and that maternal miRNA can traffic to the placenta and even into the fetal compartment. These findings define an extraordinary means of nonhormonal, miRNA-based communication between the placenta and feto-maternal compartments.-Chang, G., Mouillet, J.-F., Mishima, T., Chu, T., Sadovsky, E., Coyne, C. B., Parks, W. T., Surti, U., Sadovsky, Y. Expression and trafficking of placental microRNAs at the feto-maternal interface.

Rapid G0/1 transition and cell cycle progression in CD8+ T cells compared to CD4+ T cells following in vitro stimulation.

T-cell population consists of two major subsets, CD4+ T cells and CD8+ T cells, which can be distinguished by the expression of CD4 or CD8 molecules, respectively. Although they play quite different roles in the immune system, many of their basic cellular processes such as proliferation following stimulation are presumably common. In this study, we have carefully analyzed time-course of G0/1 transition as well as cell cycle progression in the two subsets of quiescent T-cell population following in vitro growth stimulation. We found that CD8+ T cells promote G0/1 transition more rapidly and drive their cell cycle progression faster compared to CD4+ T cells. In addition, expression of CD25 and effects of its blockade revealed that IL-2 is implicated in the rapid progression, but not the earlier G0/1 transition, of CD8+ T cells.

Rapid proliferation of activated lymph node CD4(+) T cells is achieved by greatly curtailing the duration of gap phases in cell cycle progression.

Peripheral T cells are in G0 phase and do not proliferate. When they encounter an antigen, they enter the cell cycle and proliferate in order to initiate an active immune response. Here, we have determined the first two cell cycle times of a leading population of CD4(+) T cells stimulated by PMA plus ionomycin in vitro. The first cell cycle began around 10 h after stimulation and took approximately 16 h. Surprisingly, the second cell cycle was extremely rapid and required only 6 h. T cells might have a unique regulatory mechanism to compensate for the shortage of the gap phases in cell cycle progression. This unique feature might be a basis for a quick immune response against pathogens, as it maximizes the rate of proliferation.

The unique expression and function of miR-424 in human placental trophoblasts.

Placental hypoperfusion causes cellular hypoxia and is associated with fetal growth restriction and preeclampsia. In response to hypoxia, the repertoire of genes expressed in placental trophoblasts changes, which influences key cellular processes such as differentiation and fusion. Diverse miRNAs were recently found to modulate the cellular response to hypoxia. Here we show that miR-424, which was previously shown to be upregulated by hypoxia in nontrophoblastic cell types, is uniquely downregulated in primary human trophoblasts by hypoxia or chemicals known to hinder cell differentiation. We also identify FGFR1 as a direct target of miR-424 in human trophoblasts. This effect is unique to miR-424 and is not seen with other members of this miRNA family that are expressed in trophoblasts, such as miR-15 and miR-16. Our findings establish a unique role for miR-424 during differentiation of human trophoblasts.

The lipase cofactor CGI58 controls placental lipolysis.

In eutherians, the placenta plays a critical role in the uptake, storage, and metabolism of lipids. These processes govern the availability of fatty acids to the developing fetus, where inadequate supply has been associated with substandard fetal growth. Whereas lipid droplets are essential for the storage of neutral lipids in the placenta and many other tissues, the processes that regulate placental lipid droplet lipolysis remain largely unknown. To assess the role of triglyceride lipases and their cofactors in determining placental lipid droplet and lipid accumulation, we assessed the role of patatin like phospholipase domain containing 2 (PNPLA2) and comparative gene identification-58 (CGI58) in lipid droplet dynamics in the human and mouse placenta. While both proteins are expressed in the placenta, the absence of CGI58, not PNPLA2, markedly increased placental lipid and lipid droplet accumulation. These changes were reversed upon restoration of CGI58 levels selectively in the CGI58-deficient mouse placenta. Using co-immunoprecipitation, we found that, in addition to PNPLA2, PNPLA9 interacts with CGI58. PNPLA9 was dispensable for lipolysis in the mouse placenta yet contributed to lipolysis in human placental trophoblasts. Our findings establish a crucial role for CGI58 in placental lipid droplet dynamics and, by extension, in nutrient supply to the developing fetus.

MiR-205 silences MED1 in hypoxic primary human trophoblasts.

Acting through degradation of target mRNA or inhibition of translation, microRNAs (miRNAs) regulate development, differentiation, and cellular response to diverse cues. We analyzed changes in miRNA expression in human placental trophoblasts exposed to hypoxia, which may result from hypoperfusion and placental injury. Using an miRNA microarray screen, confirmed by Northern blot analysis, we defined a set of seven miRNAs (miR-93, miR-205, miR-224, miR-335, miR-424, miR-451, and miR-491) that are differentially regulated in primary trophoblasts exposed to hypoxia. We combined in silico prediction of miRNA targets with gene expression profiling data to identify a series of potential targets for the miRNAs, which were further analyzed using luciferase reporter assays. Among experimentally confirmed targets, we found that the transcriptional coactivator MED1, which plays an important role in placental development, is a target for miR-205. Using gain- and loss-of-function assays, we confirmed that miR-205 interacts with a specific target in the 3'-UTR sequence of MED1 and silences MED1 expression in human trophoblasts exposed to hypoxia, suggesting that miR-205 plays a role in trophoblast injury.

Identification of obstructive jaundice-related microRNAs in mouse liver.

BACKGROUND/AIMS: Although microRNAs are known to be post-transcriptional regulators in physiological and pathological events in the liver, their role in the obstructive jaundice liver remains unclear. METHODOLOGY: We sequenced the small RNA libraries of the bile duct ligation (BDL) mouse liver to detect the in vivo microRNA expression profiles of obstructive jaundice. We also validated the differential expression of microRNAs in the BDL liver using real-time PCR. Laser microdissection was performed to identify the origin of BDL-related microRNAs. An IL6-treated normal intrahepatic biliary epithelial cell line was used as an in vitro model of obstructive jaundice. RESULTS: We found microRNAs that were upregulated in the BDL liver (let-7a, let-7d, let-7f, let-7g, miR-21, miR-125a-5p, miR-125b-5p, miR-194, miR-199a-3p, miR-199a-5p, miR-214, miR-221, and miR-486). Furthermore, laser-microdissection analysis showed that miR-199a-5p was significantly upregulated in the intrahepatic bile duct of the BDL liver. The in vitro expression of miR-199a-5p was appreciably elevated in accordance with increased proliferation of IL6-treated cells. CONCLUSIONS: We revealed dynamic changes in microRNA expression during obstructive jaundice using the BDL model. MiR-199a-5p was likely associated with the proliferation of intrahepatic bile ducts. Our data will facilitate further study of the pathophysiological role(s) of microRNAs in the obstructive jaundice liver.

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.

Overexpression of PIK3CA is associated with lymph node metastasis in esophageal squamous cell carcinoma.

The genomic region containing PIK3CA was found to be amplified in esophageal squamous cell carcinoma (ESCC) tissue. PIK3CA at 3q26, which encodes the p110alpha catalytic subunit of phosphatidylinositol (PI) 3-kinase, is a unique intracellular signal transducer characterized by its lipid substrate specificity. In order to characterize PIK3CA in ESCC, we investigated hot-spot mutations in exons 1, 9 and 20, the copy number gain, the expression levels of mRNA and protein. Analysis in exon 9 of the PIK3CA gene revealed mutation in 7.7% (4 of 52) of ESCC samples. No mutation was detected in either exon 1 or exon 20. Copy number amplifications of PIK3CA were found in 12 of the 45 patients (26.7%). PIK3CA mRNAs were examined in 37 ESCC patients as determined by quantitative RT-PCR and the mean mRNA level of PIK3CA in ESCC tissues was 2.61-fold higher compared with that in corresponding non-tumorous esophageal epithelia (P<0.001). Immunohistochemically, positive immunoreaction for PIK3CA was detectable in 33 of 66 (50.0%) ESCC cases, while it was not detectable in the remaining 33 cases. Furthermore, comparing the cases with negative staining with those with positive staining for PIK3CA, the presence of node metastasis was significantly correlated with those with positive staining (P<0.05). This study is the first report providing comprehensive analysis of PIK3CA expression in ESCC. These results indicate that PIK3CA may play a crucial role in the development of ESCC and serve as an indicator for lymph node metastasis.

MicroRNA profiling of human intrahepatic cholangiocarcinoma cell lines reveals biliary epithelial cell-specific microRNAs.

Intrahepatic cholangiocarcinoma (ICC), which arises in the small bile ducts of the liver, is the second most common liver malignancy. Although modulation of microRNA (miRNA) expression has been shown to be a potent sign of malignant tumors, miRNA profiles of ICC remains unclear. We performed sequencing analysis of the small RNA libraries of 2 ICC cell lines (HuCCT1 and MEC) and one normal intrahepatic biliary epithelial cell line (HIBEpiC) to produce the miRNA profiles of ICC in vitro. Furthermore, by means of the real-time polymerase chain reaction (PCR) we validated the differential expression of miRNAs cloned exclusively or predominantly from each of the cell lines. A total of 35,759 small RNA clones were obtained from the 3 cell lines. We identified 27 miRNAs that were expressed exclusively or predominantly in each cell line. Subsequent validation with the real-time PCR confirmed that the miRNAs hsa-miR-22, -125a, -127, -199a, -199a*, -214, -376a, and -424 were expressed specifically in HIBEpiC but were downregulated in the ICC cell lines. Our study provides important information for facilitating studies of the functional role(s) of miRNAs in carcinogenesis of the hepatobiliary system. The biliary epithelial cell-specific miRNAs identified in this study may serve as potential biomarkers for ICC.

SnoN overexpression is predictive of poor survival in patients with esophageal squamous cell carcinoma.

BACKGROUND: Earlier studies have identified the minimal overlapping region of amplification at 3q26 in esophageal squamous cell carcinoma (ESCC) by comparative genomic hybridization (CGH) analysis. These include PIK3CA which encodes the p110alpha catalytic subunit of phosphatidylinositol (PI) 3-kinase, a telomerase RNA component (TERC), a squamous cell carcinoma-related oncogene (SCCRO), ecotropic viral integration site-1 (EVI-1), and a Ski-related novel oncogene (SnoN). In the present study, we investigated the mRNA levels of four candidate genes (TERC, SCCRO, EVI-1, and SnoN) to determine whether genes other than PIK3CA are targets for amplification at 3q26 in ESCC. And also, we examined SnoN expression in ESCC samples. METHODS: Fifty-nine representative cases with ESCC were selected from our archives. We performed quantitative RT-PCR of four candidate genes (TERC, SCCRO, EVI-1, and SnoN) and immunohistochemistry for SnoN. Finally, we correlated these findings with the clinicopathological characteristics to determine their interrelationship. RESULTS: Among the four genes we tested, only SnoN mRNA was consistently overexpressed in primary ESCC, compared with those in corresponding nontumorous esophageal epithelia (P < 0.001). Immunoreactive SnoN was detectable in 31 of 59 (52.5%) esophageal squamous cell carcinoma specimens. The levels of SnoN expression were found to correlate with the depth of invasion and recurrence (P < 0.05). Furthermore, patients with positive staining for SnoN displayed more unfavorable outcomes than patients with negative staining (P < 0.05). CONCLUSION: SnoN is likely to be the target of the amplification at 3q26 in ESCC and plays an important role in the development of ESCC, influencing disease-specific survival.

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.

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.

Intact feto-placental growth in microRNA-210 deficient mice.

MicroRNA-210 (miR-210) has been implicated in homeostatic adaptation during hypoxia. We hypothesized that miR-210 deficiency impacts feto-placental growth. As expected, mir-210 knockout (ko) mice exhibited markedly reduced placental miR-210 expression, compared to wild-type (wt) mice. Mating of mir-210 heterozygotes resulted in near Mendelian progeny distribution, with insignificant differences between wt and ko animals with regard to embryo or placental weight and gross morphology. Intriguingly, exposure of mice to non-severe hypoxia (O2 = 12%) between E11.5-E17.5 reduced placental miR-210 expression, with slight expression changes of some miR-210 target mRNAs. Thus, miR-210 is likely dispensable for feto-placental growth in normoxia or non-severe hypoxia.

Determinants of effective lentivirus-driven microRNA expression in vivo.

Manipulation of microRNA (miRNA) levels, including overexpression of mature species, has become an important biological tool, even motivating miRNA-based therapeutics. To assess key determinants of miRNA overexpression in a mammalian system in vivo, we sought to bypass the laborious generation of a transgenic animal by exploiting placental trophoblast-specific gene manipulation using lentiviral vectors, which has been instrumental in elucidating trophoblast biology. We examined the impact of several key components of miRNA stem loops and their flanking sequences on the efficiency of mature miRNA expression in vivo. By combining established and novel approaches for miRNA expression, we engineered lentivirus-driven miRNA expression plasmids, which we tested in the mouse placenta. We found that reverse sense inserts minimized single-strand splicing and degradation, and that maintaining longer, poly-A-containing arms flanking the miRNA stem-loop markedly enhanced transgenic miRNA expression. Additionally, we accomplished overexpression of diverse mammalian, drosophila, or C. elegans miRNAs, either based on native context or using a "cassette" replacement of the mature miRNA sequence. Together, we have identified primary miRNA sequences that are paramount for effective expression of mature miRNAs, and validated their role in mice. Principles established by our findings may guide the design of efficient miRNA vectors for in vivo use.

The expression of SCDGF/PDGF-C/fallotein and SCDGF-B/PDGF-D in the rat central nervous system.

We examined the expression patterns of the two homologous genes, spinal cord-derived growth factor (SCDGF)/platelet-derived growth factor (PDGF)-C/fallotein and SCDGF-B/PDGF-D in the rat central nervous system. In the spinal cord, SCDGF/PDGF-C/fallotein was expressed in the floor plate at embryonic day (E) 11 and also in the ventricular zone at E16 but not in adult. However, SCDGF-B/PDGF-D was prominently expressed in the adult motoneurons, although faint expression was observed in the ventral ventricular zone at E16. Also in the brain, the expression of SCDGF/PDGF-C/fallotein was more remarkable at E16 than at adult. It was highly expressed in the cortex, pontine area and choroid plexus at E16. Contrary to SCDGF/PDGF-C/fallotein, SCDGF-B/PDGF-D expression was notable in several nuclei at adult.

The expression and post-transcriptional regulation of FSTL1 transcripts in placental trophoblasts.

INTRODUCTION: Follistatin-like-1 (FSTL1) is a widely expressed secreted protein with diverse but poorly understood functions. Originally described as a pro-inflammatory molecule, it has recently been reported to play a role in signaling pathways that regulate development and homeostasis. Distinctively, FSTL1 harbors within its 3'-UTR the sequence encoding microRNA-198 (miR-198), shown to be inversely regulated relative to FSTL1 expression and to exhibit opposite actions on cellular processes such as cell migration. We sought to investigate the expression of FSTL1 and to assess its interplay with miR-198 in human trophoblasts. METHODS: We used a combination of northern blot analyses, quantitative PCR, small RNA sequencing, western blot and immunohistochemistry to characterize FSTL1 and miR-198 expression in placental trophoblasts. We also used reporter assays to examine the post-transcriptional regulation of FSTL1 and assess its putative regulation by miR-198. RESULTS: We detected the expression of FSTL1 transcript in both the human extravillous trophoblast line HTR-8/SVneo and in primary term human villous trophoblasts. We also found that the expression of FSTL1 was largely restricted to extravillous trophoblasts. Hypoxia enhanced the expression of FSTL1 protein in cultured primary villous trophoblasts. Interestingly, we did not detect any evidence for expression or function of mature miR-198 in human trophoblasts. DISCUSSION: Our data indicate that placental FSTL1 is expressed particularly in extravillous trophoblasts. We also found no evidence for placental expression of miR-198, or for its regulation of FSTL1, implying that the post-transcriptional regulation of FSTL1 by miR-198 is tissue specific.

Fc gamma receptor IIb participates in maternal IgG trafficking of human placental endothelial cells.

The human placental transfer of maternal IgG is crucial for fetal and newborn immunity. Low-affinity immunoglobulin gamma Fc region receptor IIb2 (FCGR2B2 or FcγRIIb2) is exclusively expressed in an IgG-containing, vesicle-like organelle (the FCGR2B2 compartment) in human placental endothelial cells; thus, we hypothesized that the FCGR2B2 compartment functions as an IgG transporter. In this study, to examine this hypothesis, we performed in vitro bio-imaging analysis of IgG trafficking by FCGR2B2 compartments using human umbilical vein endothelial cells transfected with a plasmid vector containing enhanced GFP-tagged FCGR2B2 (pFCGR2B2-EGFP). FCGR2B2-EGFP signals were detected as intracellular vesicular structures similar to FCGR2B2 compartments in vivo. The internalization and transcytosis of IgG was significantly higher in the pFCGR2B2-EGFP-transfected cells than in the mock-transfected cells, and the majority of the internalized IgG was co-localized with the FCGR2B2-EGFP signals. Furthermore, we isolated FCGR2B2 compartments from the human placenta and found that the Rab family of proteins [RAS-related protein Rab family (RABs)] were associated with FCGR2B2 compartments. Among the RABs, RAB3D was expressed predominantly in placental endothelial cells. The downregulation of RAB3D by small interfering RNA (siRNA) resulted in a marked reduction in the FCGR2B2-EGFP signals at the cell periphery. Taken together, these findings suggest that FCGR2B2 compartments participate in the transcytosis of maternal IgG across the human placental endothelium and that RAB3D plays a role in regulating the intracellular dynamics of FCGR2B2 compartments.

Expression of DDAH1 in chick and rat embryos.

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is an enzyme that metabolizes methylated arginine to citrulline and methylamine, thus working to produce nitric oxide (NO). We isolated a gene encoding chick DDAH1. In situ hybridization analysis revealed characteristic DDAH1 mRNA expression in the embryonic spinal cord, which was especially strong in the ventral horn and dorsal root ganglion (DRG). DDAH1 was also detected in the brain, kidney, digestive tract, and in other tissues. We examined the expression pattern of DDAH1 in developing rats and compared this with the expression pattern in chicks. The expression pattern in the rats was very similar to that in the chicks, but there were some differences between the chicks and rats in the amount of DDAH1 detected in the heart, liver, lung, and DRG. We also investigated neural nitric oxide synthase (nNOS) mRNA expression patterns in rat embryos. The DDAH1 expression patterns were completely different from nNOS expression patterns. Our study suggests that DDAH1 plays an important role in development.