Departamento de Ciencias Básicas, Facultad de Medicina, Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, 4090541, Concepción, Chile.
Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Laboratorio de Antioxidantes, Universidad de Concepción. Barrio Universitario s/n, Box 160-C, Concepción, Chile.
J Physiol Biochem. 2019 Jun;75(2):209-215. doi: 10.1007/s13105-019-00679-3. Epub 2019 Apr 24.
The mammary gland increases energy requirements during pregnancy and lactation to support epithelial proliferation and milk nutrients synthesis. Lactose, the principal carbohydrate of the milk, is synthetized in the Golgi of mammary epithelial cells by lactose synthase from glucose and UPD galactose. We studied the temporal changes in the expression of GLUT1 and GLUT8 in mammary gland and their association with lactose synthesis and proliferation in BALB/c mice. Six groups were used: virgin, pregnant at 2 and 17 days, lactating at 2 and 10 days, and weaning at 2 days. Temporal expression of GLUT1 and GLUT8 transporters by qPCR, western blot and immunohistochemistry, and its association with lactalbumin, Ki67, and cytokeratin 18 within mammary tissue was studied, along with subcellular localization. GLUT1 and GLUT8 transporters increased their expression during mammary gland progression, reaching 20-fold increasing in GLUT1 mRNA at lactation (p < 0.05) and 2-fold at protein level for GLUT1 and GLUT8 (p < 0.05 and 0.01, respectively). The temporal expression pattern was shared with cytokeratin 18 and Ki67 (p < 0.01). Endogenous GLUT8 partially co-localized with 58 K protein and α-lactalbumin in mammary tissue and with Golgi membrane-associated protein 130 in isolated epithelial cells. The spatial-temporal synchrony between expression of GLUT8/GLUT1 and alveolar cell proliferation, and its localization in cis-Golgi associated to lactose synthase complex, suggest that both transporters are involved in glucose uptake into this organelle, supporting lactose synthesis.
在怀孕和哺乳期,乳腺会增加能量需求,以支持上皮细胞增殖和乳汁营养物质的合成。乳糖是乳汁的主要碳水化合物,由乳糖合酶从葡萄糖和 UDP 半乳糖合成。我们研究了 BALB/c 小鼠乳腺中 GLUT1 和 GLUT8 的表达随时间的变化,及其与乳糖合成和增殖的关系。使用了 6 个组:处女、怀孕 2 天和 17 天、泌乳 2 天和 10 天、断奶 2 天。通过 qPCR、western blot 和免疫组织化学研究了 GLUT1 和 GLUT8 转运蛋白的时空表达,及其与乳白蛋白、Ki67 和细胞角蛋白 18 在乳腺组织中的关系,同时还研究了其亚细胞定位。GLUT1 和 GLUT8 转运蛋白在乳腺发育过程中表达增加,在泌乳时 GLUT1mRNA 增加 20 倍(p<0.05),GLUT1 和 GLUT8 的蛋白水平分别增加 2 倍(p<0.05 和 0.01)。这种时空表达模式与细胞角蛋白 18 和 Ki67 共享(p<0.01)。内源性 GLUT8 与 58K 蛋白和α-乳白蛋白在乳腺组织中部分共定位,与分离的上皮细胞中的高尔基膜相关蛋白 130 共定位。GLUT8/GLUT1 的表达与肺泡细胞增殖的时空同步性,以及其在与乳糖合酶复合物相关的顺式高尔基体内的定位,表明这两种转运蛋白都参与了葡萄糖进入这个细胞器,以支持乳糖的合成。