Regulation of cytoskeletal proteins involved in cell contact formation during differentiation of granulosa cells on extracellular matrix.

Abstract

The organzation and the expression of cytoskeletal proteins involved in determining cell contact and shape were analyzed in granulosa cells during their differentiation on extracellular matrix (ECM)-coated culture plates. Rat granulosa cells from preovulatory follicles displayed an epithelial shape on ECM and formed multilayered aggregates with numerous gap junctions between neighboring cells. These cells had few actin cables and often only a diffuse pattern of actin and a low amount of vinculin in very thin focal adhesion sites. In contrast, cells grown on plastic formed a monolayer of fiat cells with a reduced number of gap junctions but with numerous stress fibers and abundant large vinculin-containing focal contacts. On ECM, the cells were stimulated to produce high levels of progesterone, while only trace amounts of the steroid accumulated in cells on plastic dishes. Two-dimensional gel electrophoretic analysis of [35Smethionine-labeled cells revealed a dramatic decrease in vinculin, a-ain, and actin synthesis in cells grown on ECM, as compared to cells grown on plastic, while the synthesis of the tubulins and of the intermediate filament protein vimentin remained unchanged. RNA blot analysis showed a marked decrease in actin mRNA levels in cells from ECM plates, while the level of tubulin mRNA remained essentially unchanged. It is concluded that the differentiation of granulesa cells on ECM in vitro is associated with changes in cell shape and cell contacts add that such changes in cell morphology are accompanied by simultaneous alterations in the organization and expression of cytoskeletal proteins that are involved in determining these cellular structures.Numerous lines of evidence suggest that important growthrelated cellular functions such as cell proliferation (1), expression of the differentiated phenotype (2-7), response to tissue-specific hormones (8), and tissue morphogenesis during embryonic development (9, 10) are modulated through changes in cell shape (for reviews, see refs. 11 and 12). Since cytoskeletal elements are responsible for determining cell morphology and shape, our studies on cell configurationrelated gene expression (13)(14)(15)(16)(17) were directed toward investigating the possible existence of a linkage between the expression of genes coding for cytoskeletal proteins and the organization in the cell of the respective proteins (for reviews, see refs. 18 and 19).The extracellular matrix (ECM), a natural substrate produced by cells, affects cell proliferation, migration, and differentiation in vivo (20)(21)(22)(23). The culturing of cells on ECM was shown to enhance cell differentiation (7, 9) and also to affect cell shape via reorganization of the cytoskeletal networks (24,25). In previous studies, it was found that granulosa cells associated with the basement membrane, in the preovulatory follicle, contained a higher density of receptors to luteinizing hormone and a higher steroidogenic activity as compared to more distal cell layers (26,27). In this report, we studied th...

Suppression of tumorigenicity in simian virus 40-transformed 3T3 cells transfected with alpha-actinin cDNA.

“…We have studied a-actinin, since it is a major component involved in microfilament stabilization and in linking microfilaments to AJs (34). In addition, a-actinin expression is modulated during growth activation and differentiation (21)(22)(23)(24) and is significantly decreased in SVT2 cells. The relationship between a-actinin expression and the tumorigenic phenotype was addressed directly by elevating a-actinin levels in tumor cells that express diminished amounts of this protein.…”

“…For example, after serum stimulation of quiescent 3T3 cells and in regenerating liver, the expression of a-actinin is elevated (21). In contrast, during steroidogenesis (22,23) and adipogenesis (24), a-actinin synthesis is reduced.…”

Induction of albumin gene transcription in hepatocytes by extracellular matrix proteins.

“…By utilizing different culture substrata, matrices have been identified which support differentiated function in a variety of cell types (8,15,16,18) including epithelial cells (2,10,17,20,23). In primary cultures of hepatocytes, albumin synthesis and secretion is maintained for several weeks when cells are plated on a basement membrane-like matrix derived from the Engelbreth-Holm-Swarm mouse sarcoma tumor (EHS gel; described in reference 19) (4).…”

Ambulante Nachsorge aus gesundheitsökonomischer Sicht

“…16 In rat and human granulosa cells, progesterone levels have been shown to be increased in the presence of bovine corneal endothelial ECM, HR9 mouse endodermal ECM, fibronectin, laminin, and type I collagen, but decreased with Matrigel. 21,28,29,34,39,41,46 In contrast, human granulosa cells plated on laminin have decreased progesterone levels compared with uncoated plates. 56 Type I collagen coating, type I collagen gels, poly-hema modified plates, and heparincoated plates affect the production of progesterone negatively in ovine granulosa cells isolated from large follicles (4 to 7 mm).…”