De Santis L, Gandolfi F, Pennarossa G, Maffei S, Gismano E, Intra G, Candiani M, Brevini T A L
Department of Ob/Gyn IVF Unit, San Raffele Scientific Institute, Milan, Italy,
J Assist Reprod Genet. 2015 Apr;32(4):645-52. doi: 10.1007/s10815-015-0437-y. Epub 2015 Jan 27.
In this study we hypothesized that the mRNA vector Staufen mediates RNA relocalization during meiotic maturation, and by virtue of its interactions with endoplasmic reticulum, provides a possible mechanism by which protein synthesis is regulated.
We assessed the expression of staufen (STAU) and calreticulin (CALR), the latter adopted as a marker of the endoplasmic reticulum, in human oocytes at different stages of maturation: GV, metaphase MI and MII. Oocytes were subjected to polymerase chain reaction in order to investigate the expression of STAU and CALR. The corresponding protein products were identified by immunofluorescence and confocal laser scanning microscopy.
STAU and CALR were constantly expressed and selectively localized during oocyte maturation. At the GV stage the both proteins displayed a dispersed distribution localization throughout the cytoplasm. Progressing to the MII stage, STAU tended to compartmentalize towards the cortical area of the oocyte clustering in granules of larger sizes. At the MII stage, CALR assumed a pattern reminiscent and possibly coincident with the position of the meiotic spindle.
The changing pattern of STAU distribution during meiotic maturation of human oocytes implicates a novel mechanism for the regulation of protein synthesis based on mRNA localization. Moreover, the unique disposition of CALR at the MII spindle uncovers a physical interaction with endoplasmic reticulum that may mediate cytoskeletal remodelling during oocyte maturation.
在本研究中，我们假设mRNA载体Staufen在减数分裂成熟过程中介导RNA重新定位，并凭借其与内质网的相互作用，提供了一种调节蛋白质合成的可能机制。
我们评估了在不同成熟阶段的人类卵母细胞中Staufen（STAU）和钙网蛋白（CALR，后者作为内质网的标志物）的表达：GV期、中期MI和MII期。对卵母细胞进行聚合酶链反应以研究STAU和CALR的表达。通过免疫荧光和共聚焦激光扫描显微镜鉴定相应的蛋白质产物。
STAU和CALR在卵母细胞成熟过程中持续表达并选择性定位。在GV期，这两种蛋白质在整个细胞质中呈分散分布。进入MII期后，STAU倾向于向卵母细胞的皮质区域分隔，聚集在较大尺寸的颗粒中。在MII期，CALR呈现出一种与减数分裂纺锤体位置相似且可能重合的模式。
人类卵母细胞减数分裂成熟过程中STAU分布模式的变化暗示了一种基于mRNA定位的蛋白质合成调节新机制。此外，CALR在MII纺锤体处的独特分布揭示了其与内质网的物理相互作用，这可能在卵母细胞成熟过程中介导细胞骨架重塑。
