Rounded Cells (rounded + cell)

Distribution by Scientific Domains


Selected Abstracts


Calyculin A,induced actin phosphorylation and depolymerization in renal epithelial cells

CYTOSKELETON, Issue 4 2003
Luo Gu
This study reports actin phosphorylation and coincident actin cytoskeleton alterations in renal epithelial cell line, LLC-PK1. Serine phosphorylation of actin was first observed in vitro after the cell lysate was incubated with phosphatase inhibitors and ATP. Both the phosphorylated actin and actin kinase activities were found in the cytoskeletal fraction. Actin phosphorylation was later detected in living LLC-PK1 cells after incubation with the phosphatase inhibitor calyculin A. Calyculin A,induced actin phosphorylation was associated with reorganization of the actin cytoskeleton, including net actin depolymerization, loss of cell-cell junction and stress fiber F-actin filaments, and redistribution of F-actin filaments in the periphery of the rounded cells. Actin phosphorylation was abolished by 3-h ATP depletion but not by the non-specific kinase inhibitor staurosporine. These results demonstrate that renal epithelial cells contain kinase/phosphatase activities and actin can be phosphorylated in LLC-PK1 cells. Actin phosphorylation may play an important role in regulating the organization of the actin cytoskeleton in renal epithelium. Cell Motil. Cytoskeleton 54:286,295, 2003. © 2003 Wiley-Liss, Inc. [source]


Differentiation of human ameloblast-lineage cells in vitro

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2006
Qiaomei Yan
Previous studies have shown that ameloblast-like cells can be selectively cultured from the enamel organ in a serum-free medium with low calcium concentrations. The purpose of this study was to further characterize this culture system to identify differentiated ameloblast-lineage cells. Tooth organs from 19,24-wk-old fetal cadavers were either frozen and cryosectioned for immunostaining, or digested in collagenase/dispase for cell culture. The cells were grown in keratinocyte media supplemented with 0.05 mM calcium, and characterized by morphology and immunofluorescence. Epithelial clones with two distinct morphologies, including smaller cobblestone-shaped cells and larger (5,15 times in size) rounded cells, began to form between day 8 and day 12 after culture. The cobblestone-shaped cells continued to proliferate in culture, while the larger cells proliferated slowly or not at all. These larger cells formed filopodia, usually had two or more nuclei and a radiating cytoplasm at the cell margin, and were more abundant with increasing time in culture. Both cell types stained for cytokeratin 14, and the larger cells appeared more differentiated, showing stronger staining for amelogenin and ameloblastin. Immunofluorescence of the tooth bud sections showed staining for these matrix proteins as ameloblasts differentiated from the inner enamel epithelium. These results show the successful culture of differentiating ameloblast-lineage cells, and lay a foundation for use of these cells to further understand ameloblast biology with application to tooth enamel tissue engineering. [source]


Control of chondrocyte gene expression by actin dynamics: a novel role of cholesterol/Ror-, signalling in endochondral bone growth

JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 9b 2009
Anita Woods
Abstract Elucidating the signalling pathways that regulate chondrocyte differentiation, such as the actin cytoskeleton and Rho GTPases, during development is essential for understanding of pathological conditions of cartilage, such as chondrodysplasias and osteoarthritis. Manipulation of actin dynamics in tibia organ cultures isolated from E15.5 mice results in pronounced enhancement of endochondral bone growth and specific changes in growth plate architecture. Global changes in gene expression were examined of primary chondrocytes isolated from embryonic tibia, treated with the compounds cytochalasin D, jasplakinolide (actin modifiers) and the ROCK inhibitor Y27632. Cytochalasin D elicited the most pronounced response and induced many features of hypertrophic chondrocyte differentiation. Bioinformatics analyses of microarray data and expression validation by real-time PCR and immunohistochemistry resulted in the identification of the nuclear receptor retinoid related orphan receptor-, (Ror-,) as a novel putative regulator of chondrocyte hypertrophy. Expression of Ror-, target genes, (Lpl, fatty acid binding protein 4 [Fabp4], Cd36 and kruppel-like factor 5 [Klf15]) were induced during chondrocyte hypertrophy and by cytochalasin D and are cholesterol dependent. Stimulation of Ror-, by cholesterol results in increased bone growth and enlarged, rounded cells, a phenotype similar to chondrocyte hypertrophy and to the changes induced by cytochalasin D, while inhibition of cholesterol synthesis by lovastatin inhibits cytochalasin D induced bone growth. Additionally, we show that in a mouse model of cartilage specific (Col2-Cre) Rac1, inactivation results in increased Hif-1, (a regulator of Rora gene expression) and Ror-,+ cells within hypertrophic growth plates. We provide evidence that cholesterol signalling through increased Ror-, expression stimulates chondrocyte hypertrophy and partially mediates responses of cartilage to actin dynamics. [source]


Well-differentiated neuroendocrine carcinoma (malignant carcinoid) of the extrahepatic biliary tract: report of two cases and literature review

APMIS, Issue 8 2010
SALVATORE SQUILLACI
Squillaci S, Marchione R, Piccolomini M, Colombo F, Bucci F, Bruno M, Bisceglia M. Well-differentiated neuroendocrine carcinoma (malignant carcinoid) of the extrahepatic biliary tract: report of two cases and literature review. APMIS 2010; 118: 543,56. The objectives of this study were to evaluate the frequency of carcinoid tumors of the extrahepatic biliary ducts (EHBDs) and the pathologic progression and the role of surgery in the management of this disease. We describe two cases of malignant carcinoids of the EHBDs, which presented as common bile duct tumors in two adult male patients, aged 52 and 70 years, who were diagnosed histologically on surgical resection specimens. A comprehensive review of the literature has also been performed with a focus on survival data. Microscopically, the tumors presented herein were composed of relatively small rounded cells with a trabecular or nesting pattern. Both cases were diffusely immunopositive for chromogranin and synaptophysin, and one of them was also focally reactive with somatostatin and pancreatic polypeptide. There was no expression in any of these tumors of thyroid transcription factor-1 (TTF-1), gastrin, insulin, glucagon, vasoactive intestinal peptide (VIP) and prolactin. The tumor showed transmural invasion in both cases, with lymph node metastasis and subcapsular liver tissue infiltration in one. Both patients are alive with no evidence of disease 41 months and 59 months, respectively, after surgery. Despite being extremely uncommon, with only 70 cases reported to date, carcinoids should be included in the differential diagnosis of EHBD tumors. This study emphasizes the necessity of complete surgical resection as the gold standard treatment for these lesions, and the importance of a correct pathologic diagnosis for prognostic implications. [source]