INTRAFOLLICULAR REGULATION OF OVARIAN TGF-B1 EXPRESSION

转化生长因子β 1 （tgf - β 1）已被确定为一种潜在的重要卵巢内生长因子，因为它对卵泡膜和颗粒细胞功能的显著影响，以及tgf - β 1和卵泡发生的生长工作的定位，但我们对其在细胞水平上的调节及其与卵巢功能的关系的了解仍然存在明显的缺陷。解开TGF- beta1功能及其调控之谜是本项目的长期目标。利用猪卵巢的培养细胞和完整的半卵泡，建立了tgf - β 1表达调控模型。数据表明，尽管两种细胞类型都表达tgf - β 1mrna，但只有caa细胞表达和分泌生长因子。FSH、LH和cAMP在培养的两种分离细胞中均不刺激tgf - β切片。然而，在小的半卵泡中，FSH而不是LH会像cAMP一样刺激tgf - β的分泌。我们假设，卵泡细胞在卵泡发育过程中表达和分泌tgf - β 1，但它是在FSH作用于颗粒细胞的指导下进行的。我们进一步假设fsh刺激的颗粒细胞产物通过激活PLA/PKC信号转导系统来调节卵泡膜细胞tgf - β的表达。为了进一步阐明TGF-beta1在滤泡间的调节作用，我们将确定TGF-beta1是否在颗粒中而不在卵泡细胞中自动表达，是否通过TGF- β I型和II型受体的选择性表达介导，以及自身表达或受体表达是否随卵泡发育而改变。FSH和tgf - β在颗粒细胞中相互调节另一受体表达的程度将被确定。颗粒细胞通过分泌因子直接调节细胞膜TGF- beta1表达的程度将通过共培养实验进行检验。卵泡tgf - β 1表达是否随卵泡发育从FSH转变为LH。最后，我们将研究一种胞质蛋白的选择性颗粒细胞表达，这种胞质蛋白能够结合tgf - β 1 mRNA 5'-非翻译区的调控茎环结构，从而抑制翻译。这可能是颗粒细胞差异表达tgf - β 1 mRNA而非生长因子的机制。相信本文所述研究的完成将提供有关tgf - β 1在卵泡间、旁分泌调节方面的新颖而重要的信息，这将有助于深入了解其在卵泡发育中的作用。

Transforming growth factor beta1 (TGF-beta1) has been identified as a potentially important intraovarian growth factor due to its pronounced effects upon theca and granulosa cell function and the localization of the growth of work regarding TGF-beta1 and folliculogenesis, there remains a notable deficit in our knowledge regarding its regulation at the cellular level and how this relates to ovarian function. Solving the riddle regarding TGF- beta1 function and regulation represents the long term goals of this project. Using both cultured cells and intact hemi-follicles from the porcine ovary, a model for the regulation of TGF-beta1 expression has been formulated. Data suggest that although both cell types express TGF-beta1mRNA, only theca cells express and secrete the growth factor. Neither FSH, LH, nor cAMP stimulates TGF-beta section in either isolated cell type in culture. In small hemi-follicles, however, FSH but not LH stimulates TGF-beta1 secretion as does cAMP. We hypothesize that theca cells express and secrete TGF-beta1 during follicle development but that it is under the direction of FSH acting upon granulosa cells. We further hypothesize that a FSH-stimulated granulosa cell product regulates theca cell TGF-beta expression by activating the PLA/PKC signal transduction system. To further delineate the inter-follicular regulation of TGF-beta1 it will be established whether TGF- beta1 auto expression occurs in granulosa but not theca cells, whether this is mediated by selective expression of TGF-beta type I and II receptors, and whether auto-expression or receptor expression change with follicle development. The extent to which FSH and TGF-beta1 reciprocally regulate the expression of the other receptor in granulosa cells will be determined. The extent to which granulosa cells can directly regulate theca cell TGF- beta1 expression via secretory factors will be tested by co-culture experiments. Whether follicular TGF-beta1 expression switches from FSH to LH governance with follicle development will be determined. Lastly, the selective granulosa cell expression of a cytosolic protein capable of binding to a regulatory stem-loop structure of the TGF-beta1 mRNA 5'-untranslated region which inhibits translation will be investigated. This may be the mechanism by which granulosa cells differentially express TGF-beta1 mRNA but not the growth factor. It is believed that completion of the studies described herein will provide novel and important information regarding inter-follicular, paracrine regulation of TGF-beta1, which will provide insight into its role during follicle development.