Journal of Histochemistry & Cytochemistry

Jiang, Yi-zhou; Wang, Kai; Fang, Roy; Zheng, Jing

doi: 10.1369/jhc.2010.955955pmid: 20354149

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, mediates many biological processes, including fetal development. In this study, we examined AhR protein expression in human placentas from normal (N) and severe preeclamptic (sPE) pregnancies, as well as human fetal tissues from the second trimester of pregnancy, using immunohistochemistry and/or Western blot analysis. In the placentas, the AhR immuno-reactivity was present primarily in syncytiotrophoblasts. The AhR staining was also seen in endothelium of large blood vessels in villi and endothelium of umbilical cord arteries and veins. No difference in AhR protein levels was found between N and sPE placentas. In fetal tissues, the AhR immunoreactivity was localized in lung, kidney, esophagus, pancreas, liver, testicle, thymus gland, retina, and choroid, mainly in epithelial cells, whereas it was absent in heart, brain, sclera, and thoracic aorta. These findings suggest that the AhR plays a critical role in syncytiotrophoblasts of human placentas and epithelium of many fetal organs. These data also imply that human placentas and those fetal organs with high AhR expression (e.g., lung, kidney, liver, pancreas, and thymus gland) during fetal development are highly susceptible to environmental toxicants such as dioxin.

Kwon, Osun; Miller, Shane; Li, Nan; Khan, Akhtar; Kadry, Zakiyah; Uemura, Tadahiro

doi: 10.1369/jhc.2010.956011pmid: 20354148

In ischemic acute kidney injury, renal blood flow is decreased. We have previously shown that reperfused, transplanted kidneys exhibited ischemic injury to vascular endothelium and that preservation of peritubular capillary endothelial integrity may be critical to recovery from ischemic injury. We hypothesized that bone marrow–derived (BMD) endothelial progenitor cells (EPCs) might play an important role in renal functional recovery after ischemia. We tested this hypothesis in recipients of cadaveric renal allografts before and for 2 weeks after transplantation. We found that the numbers of circulating CD34-positive EPCs and CD146-positive endothelial cells (ECs) decreased immediately after ischemia–reperfusion. In renal allograft tissues obtained 1 hr after reperfusion, CD34-positive cells were more frequently observed along the endothelial lining of peritubular capillaries compared with non-ischemic controls. Moreover, 0–17.5% of peritubular capillary ECs were of recipient origin. In contrast, only 0.1–0.7% of tubule cells were of recipient origin. Repeat graft biopsy samples obtained 35 and 73 days after transplant did not contain capillary ECs of recipient origin, whereas 1.4% and 12.1% of tubule cells, respectively, were of recipient origin. These findings suggest that BMD EPCs and ECs may contribute to en-dothelial repair immediately after ischemia–reperfusion.

Liu, Yichen; Gao, Yan; Wu, Yan; Wu, Yonghong; Wang, Hangyan; Zhang, Chenggang

doi: 10.1369/jhc.2010.955021pmid: 20421594

Cerebral ischemia–reperfusion (I/R) insults result in neuronal cell death, brain tissue loss, and severe neurological deficits. However, the underlying mechanism is still not fully understood. Heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 belongs to a family of RNA-binding proteins that plays a central role in pre-mRNA processing. Recent studies have revealed that hnRNP A2/B1 may be involved in the progress of I/R; therefore, the present study aimed to examine expression patterns of hnRNP A2/B1 to better understand posttranscriptional regulations in cerebral I/R insults. Focal cerebral I/R models were induced by right middle cerebral artery occlusion (MCAO) for 120 min followed by 3, 6, 12, 24, 48, and 72 hr of reperfusion in male Sprague-Dawley rats. We employed immunohistochemistry to examine expression of hnRNP A2/B1 in rat cerebral cortex (including cingulate cortex, striate cortex, temporal cortex, and piriform cortex) and hippocampus after I/R insults. Results showed that expression of hnRNP A2/B1 was significantly downregulated in cerebral cortex and hippocampus from 3 to 24 hr of reperfusion after MCAO for 120 min, but significantly upregulated at 48 hr of reperfusion. Unexpectedly, translocation of hnRNP A2/B1 from nucleus to cytoplasm and even to neurites was observed in cerebral cortex at 3 hr of reperfusion, reaching a peak at 24 hr of reperfusion, but not in hippocampus, indicating different posttranscriptional regulation patterns in different brain regions. Interestingly, translocation of hnRNP A2/B1 was only observed in cerebral cortex with MCAO but not in the opposite side, suggesting an I/R–specific expression pattern in the brain. Our data suggest that hnRNP A2/B1 participates in posttranscriptional regulation of neurons in cerebral cortex and hippocampus that suffered I/R insults, although posttranscriptional regulation is more extensive in neuronal cells of cerebral cortex than in hippocampus.

Teranishi, Keitaro; Kaneko, Toyoji

doi: 10.1369/jhc.2010.955492pmid: 20421593

The kidney plays a crucial role in the regulation of water and ion balances in both freshwater and seawater fishes. However, the complicated structures of the kidney hamper comprehensive understanding of renal functions. In this study, to investigate the structure of sterically disposed renal tubules, we examined spatial, cellular, and intracellular localization of Na+/K+-ATPase in the kidney of the Japanese eel. The renal tubule was composed of the first (PT-I) and second (PT-II) segments of the proximal tubule and the distal tubule (DT), followed by the collecting ducts (CDs). Light microscopic immunocytochemistry detected Na+/K+-ATPase along the renal tubules and CD; however, the subcellular distribution of the Na+/K+-ATPase immunoreaction varied among different segments. Electron microscopic immunocytochemistry further revealed that Na+/K+-ATPase was distributed on the basal infoldings of PT-I, PT-II, and DT cells. Three-dimensional analyses showed that the renal tubules meandered in a random pattern through lymphoid tissues, and then merged into the CD, which was aligned linearly. Among the different segments, the DT and CD cells showed more-intense Na+/K+-ATPase immunoreaction in freshwater eel than in seawater-acclimated eel, confirming that the DT and CD segments are important in freshwater adaptation, or hyperosmoregulation.

Suzuki, Sayuri; Namiki, Jun; Shibata, Shinsuke; Mastuzaki, Yumi; Okano, Hideyuki

doi: 10.1369/jhc.2010.955609pmid: 20421592

Nestin is an intermediate filament protein that is known as a neural stem/progenitor cell marker. It is expressed in undifferentiated central nervous system (CNS) cells during development, but also in normal adult CNS and in CNS tumor cells. Additionally, nestin is expressed in endothelial cells (ECs) of CNS tumor tissues and of adult tissues that replenish by angiogenesis. However, the regulation of nestin expression in vascular endothelium has not been analyzed in detail. This study showed that nestin expression was observed in proliferating endothelial progenitor cells (EPCs), but not in mature ECs. In adherent cultured cells derived from bone marrow cells, EPCs that highly expressed nestin also expressed the endothelial marker CD31 and the proliferation marker Ki67. ECs cultured without growth factors showed attenuated nestin immunoreactivity as they matured. Trans-genic mice that carried the enhanced green fluorescent protein under the control of the CNS-specific second intronic enhancer of the nestin gene showed no reporter gene expression in EPCs. This indicated that the mechanisms of nestin gene expression were different in EPCs and CNS cells. Immunohistochemistry showed nestin expression in neovascular cells from two distinct murine models. Our results demonstrate that nestin can be used as a marker protein for neovascularization.

Park, Ji Young; No, Hee Sung; Ahn, You Ran; Oh, Seung Hoon; Kim, Young Seok; Kim, Sook Young; Jang, Kee Taek; Kim, Sun Wook; Chung, Jae Hoon; Min, Yong Ki; Heo, Jin Seok; Choi, Seong Ho; Choi, Dong Wook; Lee, Myung-Shik; Lee, Moon Kyu; Kim, Jae Hyeon;

Nio-Kobayashi, Junko; Iwanaga, Toshihiko

doi: 10.1369/jhc.2010.956227pmid: 20421595

Galectin-1 and galectin-3, β-galactoside–binding lectins, are predominantly expressed in the regressing corpus luteum (CL) of mouse ovary. This study revealed the expression patterns and cellular localizations of galectins during CL formation and regression by ISH and IHC. Galectin-1 mRNA expression temporarily increased in active CL, preceding the expression of progesterone degradation enzyme 20α-hydroxysteroid dehydrogenase (20α-HSD), which represents functional luteolysis. The expressions of both galectin-1 and galectin-3 remarkably increased in the structurally regressing CL, which vigorously expressed 20α-HSD and contained abundant apoptotic luteal cells. Ultrastructurally, galectin-1– and galectin-3–immunoreactive cells were identified as fibroblasts and infiltrating macrophages, respectively. In addition, some populations of luteal cells themselves expressed galectin-3 in regressing CL and formed unique demarcation membranes in the cytoplasm, showing a non-typical apoptotic feature. Ovary of adult mice with repeated estrus cycles contained CL of three different generations. Among them, the old CL formed during previous estrus cycles consisted of galectin-3–positive luteal cells. The galectin-3–positive old CL was resistant to apoptosis and seemed to be eliminated by a mechanism different from apoptosis. The stage- and cell-specific expression of galectin in CL suggests its differential contribution to luteolysis, and this expression may be mediated by major regulatory molecules of CL function, prolactin and/or prostaglandin F2α.

Weissenbacher, Tobias; Brüning, Ansgar; Kimmich, Tanja; Makovitzky, Josef; Gingelmaier, Andrea; Mylonas, Ioannis

doi: 10.1369/jhc.2010.956185pmid: 20458061

Inhibins and activins are important regulators of the female reproductive system. A novel inhibin subunit, named βC, has been identified and demonstrated to be expressed in several human tissues. We demonstrate here that inhibin βC is expressed in human placenta. Expression of the inhibin βC subunit was demonstrated at the protein level by means of immunohistochemical evaluation and at the transcriptional level by an inhibin βC-specific RT-PCR analysis. Expression of inhibin βC was detected in the human chorionic carcinoma cell lines JEG and BeWo. Although the precise role of this novel inhibin subunit in human placenta development and homeostasis is unclear, analogies with other inhibin sub-units and the strong expression of βC in normal human trophoblast cells and chorionic carcinoma cells suggest that βC may be involved in autocrine/paracrine signaling pathways, angiogenesis, decidualization, and tissue remodeling under normal and malignant conditions. Additionally, JEG and BeWo express βC and, therefore, can be used as a cell culture model for further functional analysis of this subunit in the human placenta.

Akiyama, Kosuke; Miyashita, Takenori; Matsubara, Ai; Mori, Nozomu

doi: 10.1369/jhc.2010.956045pmid: 20458062

The endolymphatic sac (ES) is a part of the membranous labyrinth. ES is believed to perform endolymph absorption, which is dependent on several ion transporters, including Na+/K+/2Cl− cotransporter type 2 (NKCC-2) and Na+/K+-ATPase. NKCC-2 is typically recognized as a kidney-specific ion transporter expressed in the apical membrane of the absorptive epithelium. NKCC-2 expression has been confirmed only in the rat and human ES other than the kidney, but the detailed localization features of NKCC-2 have not been investigated in the ES. Thus, we evaluated the specific site expressing NKCC-2 by immunohistochemical assessment. NKCC-2 expression was most frequently seen in the intermediate portion of the ES, where NKCC-2 is believed to play an important role in endolymph absorption. In addition, NKCC-2 expression was also observed on the apical membranes of ES epithelial cells, and Na+/K+-ATPase coexpression was observed on the basolateral membranes of ES epithelial cells. These results suggest that NKCC-2 performs an important role in endolymph absorption and that NKCC-2 in apical membranes and Na+/K+-ATPase in basolateral membranes work coordinately in the ES in a manner similar to that in renal tubules.