Injection of bovine parathyroid poly(A)+ RNA into Xenopus oocytes confers sensitivity to high extracellular calcium.
Injection of bovine parathyroid poly(A)+ RNA into Xenopus oocytes confers sensitivity to high extracellular calcium.
复制标题
将牛甲状旁腺多聚 (A) RNA 注射到非洲爪蟾卵母细胞中可赋予其对高细胞外钙的敏感性。
DOI：
10.1002/jbmr.5650090219
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Shoback,DM
中科院分区：
文献类型：
--
作者：
Chen,TH;Pratt,SA;Shoback,DM
Parathyroid cells detect increments in the extracellular [Ca2+], which lead to substantial increases in intracellular free Ca2+([Ca2+]i) and, ultimately, to suppression of parathyroid hormone (PTH) secretion. To determine whether mRNA from parathyroid tissue could confer sensitivity to high extracellular Ca2+, we isolated and injected total bovine parathyroid poly(A)+RNA intoXenopus laevisoocytes. To assess translational activity of the RNA, PTH released into the media was measured. Intact PTH was detected in the medium for ≤48 h, and injection of increasing amounts of RNA (∼0.5–50 ng/oocyte) led to the release of greater quantities of PTH. We screened for the expression of a putative Ca2+sensor molecule by measuring45Ca efflux from preloaded oocytes, in response to raising extracellular [Ca2+] from 0.7 to 5.7 mM. This increment in [Ca2+] stimulated45Ca efflux by 249 ± 52 cpm over 20 min from eggs injected with parathyroid poly(A)+RNA (n= 22). This response was significantly greater than45Ca efflux from any group of controls exposed to the same change in extracellular Ca2+(p< 0.02), including oocytes injected with either water, cRNA for the platelet‐derived growth factor (PDGF) BB receptor, or T cell poly(A)+RNA. Size‐fractionation of poly(A)+RNA over sucrose gradients demonstrated that mRNA, which induced responsiveness to high extracellular Ca2+, was present in fractions with transcripts of ˜5–9 kB. Injection of these fractions also conferred sensitivity to the presence of Ba2+or Sr2+(both at 5 mM) in the media. These findings establish that parathyroid cells express mRNA for a molecule capable of detecting changes in the extracellular divalent cation concentration. This molecule may play a role in secretory responses mediated by Ca2+in the parathyroid.
