RESUMEN
Serum-free mouse embryo (SFME) cells, derived in medium in which serum is replaced with growth factors and other supplements, display distinctive properties: (i) SFME cells do not lose proliferative potential or show gross chromosomal aberration upon extended culture, (ii) these cells depend on epidermal growth factor for survival; and (iii) SFME cell proliferation is reversibly inhibited by serum. Treatment of SFME cells with serum or transforming growth factor beta led to the appearance of glial fibrillary acidic protein, a specific marker for astrocytes. The appearance of glial fibrillary acidic protein in cultures was reversed upon removal of transforming growth factor beta or serum. Cells with properties similar to SFME cells were also isolated from adult mouse brain. These results suggest a role for transforming growth factor beta in astrocyte differentiation in developing organisms and in response to injury and identify the cell type that has the unusual properties of SFME cells.
Asunto(s)
Proteína Ácida Fibrilar de la Glía/biosíntesis , Factor de Crecimiento Transformador beta/farmacología , Animales , Sangre , Células Cultivadas , Medios de Cultivo , Embrión de Mamíferos , Expresión Génica/efectos de los fármacos , Proteína Ácida Fibrilar de la Glía/genética , Proteína Ácida Fibrilar de la Glía/aislamiento & purificación , Cinética , Ratones , Ratones Endogámicos BALB C , Peso Molecular , ARN/aislamiento & purificación , ARN Mensajero/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/aislamiento & purificaciónRESUMEN
Differential screening of a cDNA library derived from mRNA of TGF beta-treated serum-free mouse embryo (astrocyte precursor) cells isolated a strongly TGF beta-regulated mRNA that codes for cystatin C, a cysteine protease inhibitor. Increase in cystatin C mRNA level was observed within four hours after treatment with picomolar concentrations of TGF beta. The increase was reversible upon removal of TGF beta and was not prevented by cycloheximide. These results suggest that cystatin C expression may represent a developmentally regulated differentiated function of astrocytes, and also suggest that cystatin C expression may be involved in the response of brain cells to platelet release of TGF beta after trauma or injury.
Asunto(s)
Cistatinas/genética , Factor de Crecimiento Transformador beta/farmacología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Células Cultivadas , Proteínas del Líquido Cefalorraquídeo/genética , Cicloheximida/farmacología , Cistatina C , Cistatinas/biosíntesis , Embrión de Mamíferos , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , ARN Mensajero/genética , Transcripción Genética/efectos de los fármacosRESUMEN
Mouse embryo cells derived in a serum-free medium formulation (SFME cells) do not exhibit growth crisis or chromosomal abnormalities and are nontumorigenic in vivo; these cells are also reversibly growth inhibited by serum or platelet-free plasma (Loo et al.; Science, 236:200-202, 1987). A portion of the inhibitory activity of serum could be extracted by charcoal, a procedure that removes steroid and thyroid hormones. Both L-3,5,3'-triiodothyronine (T3) and hydrocortisone inhibited growth of SFME cells in a reversible manner. The inhibitory activity of serum also was partially removed by treatment with anion exchange resin in a procedure designed to deplete serum of thyroid hormone. However, the effect of serum on untransformed SFME cells could not be prevented by addition of the antiglucocorticoid RU38486, and ras-transformed clones of SFME cells, which are capable of growing in serum-containing medium, retained inhibitory responses to glucocorticoid and, with some clonal variability, to T3. These results suggest that glucocorticoid or thyroid hormones may contribute to the inhibitory activity of serum on SFME cells, but additional factors are also involved.
Asunto(s)
Embrión de Mamíferos/citología , Glucocorticoides/farmacología , Hormonas Tiroideas/farmacología , Animales , División Celular/efectos de los fármacos , Línea Celular Transformada , Células Cultivadas , Medios de Cultivo/farmacología , Embrión de Mamíferos/efectos de los fármacos , Glucocorticoides/antagonistas & inhibidores , Hidrocortisona/farmacología , Ratones , Mifepristona/farmacología , Triyodotironina/farmacologíaRESUMEN
The inactivation of simian rotavirus SA-11 and human rotavirus type 2 (Wa) by ozone was compared at 4 degrees C by using single-particle virus stocks. Although the human strain was clearly more sensitive, both virus types were rapidly inactivated by ozone concentrations of 0.25 mg/liter or greater at all pH levels tested. Comparison of the virucidal activity of ozone with that of chlorine in identical experiments indicated little significant difference in rotavirus-inactivating efficiencies when the disinfectants were used at concentrations of 0.25 mg/liter or greater.
