Cell Biology International

Estrogen and progesterone, while regulating uterine functions, also regulate the number of caveolae and the level of caveolin. Large numbers of caveolae, as well as elevated expression of caveolin‐1 and caveolin‐2 isoforms in the myometrium of ovariectomised (OVX) rats were detected. 17β‐estradiol (E2) has a downregulating effect: the treatment of OVX rats with E2 (5μg/animal) reduced the formation of caveolae by approx. 90%. Western blots clearly demonstrated the reduction of membrane caveolin‐1 and −2 content. Progesterone treatment (2.5mg/animal) alone did not cause any substantial change, but prevented the effect of estrogen. Control experiments showed that the quantity of Na⁺/K⁺‐ATPase, a plasma membrane protein excluded from caveolae, was not downregulated by E2. The administration of the pure estrogen receptor (ERα) antagonist ICI 182,780 (1mg/animal) not only compensated for the inhibitory effect of E2, but further increased the level of caveolin‐1 in the myometrium of OVX rats and facilitated the formation of caveolae by ∼70%. In contrast, the partial antagonist tamoxifen (1mg/animal) mimicked the effect of estrogen. The amount of caveolin also changed during pregnancy. During the first half of pregnancy the expression of caveolin was suppressed, but it gradually increased until delivery. Our results indicate that the formation and number of caveolae are influenced by the physiological state of the uterus in a hormone dependent manner.

This study demonstrates cytotoxic and genotoxic potential of juglone, a chief constituent of walnut, and its underlying mechanisms against melanoma cells. MTT assay and clonogenic assay were used to study cytotoxicity, micronucleus assay to assess genotoxicity, glutathione (GSH) assay and 2′,7′‐dicholorofluorescein diacetate (DCFH‐DA) assay to evaluate the oxidative stress induction. Apoptosis/necrosis induction was analysed by flow cytometry. We observed a concentration‐dependent decrease in cell survival with a corresponding increase in the lactate dehydrogenase levels. A dose‐dependent increase in the frequency of micronucleated binucleate cells indicated the potential of juglone to induce cytogenetic damage in melanoma tumor cells. Moreover, results of the micronuclei study indicated division delay in the proliferating cell population by showing decrease in the cytokinesis blocked proliferation index. Further, juglone‐induced apoptosis and necrosis could be demonstrated by oligonucleosomal ladder formation, microscopic analysis, increase in the hypodiploid fraction (sub Go peak in DNA histogram), as well as an increased percentage of AnnexinV(+)/PI(+) cells detected by flow cytometry. A significant concentration‐dependent decrease in the glutathione levels and increase in dichlorofluorescein (DCF) fluorescence after juglone treatment confirmed the ability of juglone to generate intracellular reactive oxygen species. The cytotoxic effect of juglone can be attributed to mechanisms including the induction of oxidative stress, cell membrane damage, and a clastogenic action leading to cell death by both apoptosis and necrosis.

Lens epithelial cells undergo epithelial‐mesenchymal transition (EMT) after injury as in cataract extraction, leading to fibrosis of the lens capsule. We have recently shown that TGF‐β‐induced EMT in lens epithelial cells depends on PI3 kinase/Akt signal pathway. In this report, we suggest Smad3 is necessary for TGF‐β‐induced EMT by showing that the expression of dominant‐negative Smad3 blocks the expression of α‐smooth muscle actin (α‐SMA) and morphological changes. We also show that TGF‐β induces a biphasic change in Rho activity, and that Y27632, a selective inhibitor of Rho effector ROCK, inhibits TGF‐β‐induced EMT in vitro and in vivo. We finally show that Smad3 activation and Rho signal activation is independent each other. All of these findings suggest that Rho/ROCK activation together with Smad3 is necessary for TGF‐β‐induced EMT in lens epithelial cells.

Metallothionein presence and amount were determined in the unfertilized eggs of six sea urchin species by silver saturation assay and gel‐chromatography of cell extracts. The results showed high levels of metallothionein in the egg cytoplasm of the two Mediterranean species Paracentrotus lividus and Sphaerechinus granularis. No metallothionein was found either in the eggs of Arbacia lixula, or in those of the three Eastern species Strongylocentrotus intermedius, Temnopleurus hardwickii and Clypeaster japonicus. However, the extracts of the latter three species revealed the presence of zinc bound in a macromolecular form, thus suggesting the existence of metal‐binding proteins distinct from metallothioneins.

Our investigations demonstrate that proline‐containing dipeptides can provoke a chemosensory response from the unicellular Tetrahymena pyriformis The chemotactic effects of the dipeptides have a close relationship with the side chain and the lipophilicity of the amino‐terminal amino acid. Comparison of ‘mirror’ variants of proline‐containing dipeptides points to the fact that dipeptides with small side chain and non‐polar character amino acids (Gly‐Pro, Ala‐Pro) are preferred on the amino‐terminal end. In the case of amino acids with very variable side chains, small (Pro‐Gly) and the large side chain and non‐polar character amino acids (Pro‐Leu, Pro‐Phe) on the carboxyl‐terminal end can induce significant chemotactic responses. With valine on any terminus the proline‐containing dipeptide induced a weak repellent effect.

The effect of hydrostatic pressure on the paracellular ion conductance (Gp) composed of the Na⁺ conductance (G_Na) and the Cl⁻ conductance (G_Cl) has been Investigated. Gp, G_Na and G_Cl were time‐dependently increased after applying an osmotic gradient generated by NaCl with basolateral hypotonicity. Hydrostatic pressure (1–4 cm H₂O) applied from the basolateral side enhanced the osmotic gradient‐induced increase in Gp, G_Na and G_Cl in a magnitude‐dependent manner, while the hydrostatic pressure applied from the apical side diminished the osmotic gradient‐induced increase in Gp, G_Na and G_Cl. How the hydrostatic pressure influences Gp, G_Na and G_Cl under an isosmotic condition was also investigated. Gp, G_Na and G_Cl were stably constant under a condition with basolateral application of sucrose canceling the NaCl‐generated osmotic gradient (an isotonic condition). Even under this stable condition, the basolaterally applied hydrostatic pressure drastically elevated Gp, G_Na and G_Cl, while apically applied hydrostatic pressure had little effect on Gp, G_Na or G_Cl. Taken together, these observations suggest that certain factors controlled by the basolateral osmolality and the basolaterally applied hydrostatic pressure mainly regulate the Gp, G_Na and G_Cl.

Để đánh giá vai trò của yếu tố tăng trưởng tế bào gan (HGF) và androgen trong sự phát triển của các tế bào biểu mô tuyến tiền liệt, chúng tôi đã tách biệt các tế bào biểu mô tuyến tiền liệt ventral của chuột và nuôi cấy chúng trong ma trận gel collagen loại I ba chiều dưới điều kiện không có huyết thanh. Mặc dù các tế bào biểu mô tuyến tiền liệt có xu hướng chết trong môi trường cơ sở có bổ sung insulin, 5α-dihydrotestosterone (DHT) đã ngăn chặn sự chết tế bào, và HGF đã kích thích nhẹ sự phát triển. Ngược lại, sự đồng tồn tại của DHT và HGF đã gia tăng đáng kể sự phát triển và biến hình nhánh của các tế bào biểu mô. Một số sự phát triển được hình thành dưới những điều kiện này cho thấy cấu trúc mở rộng giống như các ống tuyến tiền liệt hoặc phế nang. Kiểm tra môi trường được điều chỉnh bởi các tế bào mô đệm đã tiết lộ rằng có một hoạt động kích thích tăng trưởng hiện diện trong môi trường đã điều chỉnh. Một phần lớn của hoạt động này đã bị loại bỏ bởi chống HGF IgG. Những quan sát này gợi ý rằng HGF được sản xuất bởi các tế bào mô đệm của tuyến tiền liệt và hỗ trợ sự kích thích của androgen đối với sự tăng trưởng của các tế bào biểu mô.

The size and number of secretory granules in late larval salivary glands of Drosophila melanogaster have been related to interecdysial and early metamorphic development represented by well‐known puffs in polytene chromosomes. Interecdysial period (puff stage 1 (PS1)) is characterized by presence of numerous small granules (11,000 per cell). The transition from PSI to early metamorphic phase (PS2 and upwards), induced by rapid elevation in endogenous steroid hormone ecdysone, is accompanied by continuous growth of granule diameter with concomitant reduction in their number per cell. In the PS4, just prior to secretion, ∼3000 mature granules occur per cell. The mature state is associated with the change from hyperbolic to Gaussian distribution of granule number over their size range. Similar changes in secretory granule parameters were observed in interecdysial salivary glands explanted from 3rd instar larvae and cultured in vitro in medium containing 5×10⁻⁶m ecdysone.

We have isolated mouse DLG6 (mDLG6) cDNA clones by RT‐PCR and then by using the RT‐PCR products to screen a mouse brain cDNA library. The deduced amino acid sequence of mDLG6 shows 79.2% and 82.7% overall identity to human (hDLG6) and rat DLG6 (rDLG6), respectively. In situ hybridization revealed that mDLG6 mRNA is predominantly expressed in embryonic and adult brain.