Biomedical subjects

V P Kedar

Publications and source records attributed to V P Kedar.

4 recordsLinked to original sources

PubMed1991

Regulation of laminin expression by interferon.

Regulation of laminin (LMN) expression by interferon (IFN) treatment has been studied in murine LB and 3T3 cells, human lung epithelial (A549) and foreskin fibroblast (FS4) cells, and bovine aortic endothelial cells. Using various morphological and biochemical techniques, our data show an increased expression of LMN following IFN treatment, with a corresponding increase in the mRNA levels. These observations may have considerable significance in various phases of wound healing, since exogenous LMN has been shown to increase the migration of epithelial cells and may lead to rapid healing of burn, traumatic, or infectious injuries.

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PubMed1991

Thrombin stimulation of synthesis and secretion of fibronectin by human A549 epithelial cells and mouse LB fibroblasts.

Thrombin, a serine protease generated at wound sites, takes part in multiple biological functions, including wound healing. The present report elucidates the effect of thrombin on fibronectin (FN) synthesis and secretion in fibroblasts and epithelial cells. Subconfluent cultures of mouse LB fibroblasts and human A549 epithelial cells were exposed to various concentrations of bovine plasma thrombin at 37 degrees C for 16 hr. After exposure, cells were processed for determination of cell-associated and secreted FN by metabolic labeling, immunoprecipitation, immunofluorescence, and peroxidase immunocytochemistry. The correlation of FN production with cell growth was studied by a combined procedure of peroxidase immunocytochemistry and light microscopic autoradiography. The amounts of cell-associated and secreted FN were significantly increased with dose increments of thrombin. The increases were most evident in secreted FN. The increase of cell-associated FN was also evidenced by results from immunofluorescence and immunocytochemical studies. Ultrastructurally, the intracellular FN was localized in rough endoplasmic reticulum, Golgi complexes, and secretory granules, whereas non-released extracellular FN was localized in the plasma membrane of cell-to-cell contacts and in the extracellular fibrils. More intense cytoplasmic FN staining was observed in cells that were not labeled with [3H]-thymidine, indicating that FN production may vary with different phases of cell growth. The results imply that thrombin may play an important role in the early phases of wound healing.

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PubMed1988

Purification and analysis of murine 2-5A-dependent RNase.

2-5A-dependent RNase (RNase L, RNase F) is an enzyme which mediates effects of 2-5A (px(A2'p)nA; x = 2 or 3, n greater than or equal to 2) in cells. 2-5A binding activity present in mouse liver extracts was measured using a 32P-labeled 2-5A derivative. Analysis of Scatchard plots was consistent with a single noninteracting 2-5A binding site with a Ka of 2.5 X 10(10) M-1. Similarly, affinity labeling of proteins with a 32P-labeled 2-5A derivative revealed a single, high-affinity 2-5A-binding protein of Mr 80,000. This 2-5A-binding protein was the only mouse liver protein specifically and consistently eluted by 2-5A from an affinity resin consisting of core(2-5A) covalently attached to cellulose. The 2-5A-eluted protein could degrade polyuridylic acid but not polycytidylic acid. Furthermore, when the 2-5A-eluted protein was electrophoresed into a polyuridylic acid-containing, nondenaturing gel, a band of degraded polyuridylic acid was demonstrated after incubation with 2-5A. There was no band of degraded polyuridylic acid when the elution was performed either in the absence of oligonucleotide or in the presence of low amounts of a closely related analog of 2-5A, p3I2'pA2'pA. Therefore, the Mr 80,000 2-5A-binding protein and the 2-5A-dependent RNase were almost certainly the same protein. Finally, the Mr 80,000 2-5A-binding protein was purified to homogeneity by electroelution from a polyacrylamide gel.

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PubMedDate not supplied

Interferon enhances fibronectin expression in various cell types.

Fibronectin (FN), a normal plasma and extracellular matrix glycoprotein, plays a significant role in various phases of wound healing. At wound site FN is synthesized locally by various cell types involved in the healing process (viz. epithelial, endothelial, fibroblast and macrophage cells) or deposited from the plasma. The present study was undertaken to investigate the in vitro effect of IFN on FN synthesis as well as release in the culture medium by various cell types. Indirect immunofluorescence and immunoelectron microscopy studies, using specific antibodies, revealed that IFN treatment resulted in significantly more staining for FN as compared to untreated control cells. Metabolic labeling with 35S-methionine, immunoprecipitation and SDS-page studies showed an increase in FN synthesis and release by IFN treated cells. In addition, to determine whether this increased synthesis was reflected at mRNA levels, poly (A)+ RNA was isolated from human lung epithelial cells (A549) and probed with FN specific cDNA. We found that IFN treatment increased the level of FN mRNA.

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