Targeted disruption of the Reg protein receptor gene : The relationship of the Reg-Reg receptor system with pancreatic 13-cell replication.

再生基因(Reg)编码一种分泌型蛋白，通过其受体(RegR)作为自分泌/旁分泌生长因子诱导胰腺13细胞增殖。在体外和体内积累的证据-包括使用REG转基因和REG^&lt；/-&gt；小鼠-表明REG蛋白也参与了各种组织中的再生细胞增殖，如胃肠道、神经和心血管细胞。在这里，我们用靶向干扰RegR的小鼠来研究REG-REG受体系统在组织再生和发育中的影响。杂合突变小鼠(RegR^&lt；+/-&gt；)具有正常的生育力和寿命，并保持与它们的野生型队列相似的体重和血糖水平。此外，RegR^-lt；+/-&gt；组小鼠胰腺β细胞质量与野生型无差异，但其组织中RegRmRNA和蛋白的表达水平约为野生型的一半。然后，我们与RegR^&lt；+/-&gt；小鼠进行杂交，发现完全不存在RegR^(+/-)幼鼠，这表明该基因对胚胎是致命的。杂合子的定时妊娠显示，RegR^(+/-)在性交后8.5至9.5天死亡。由于REG^(+/-)小鼠的β细胞再生活性降低，我们通过部分胰腺切除的方法诱导了REG^(+/-)小鼠胰腺β细胞的复制。手术后，RegR^(+/-)小鼠胰腺β细胞的BrdU掺入率和增殖细胞核抗原阳性细胞数均低于RegR^(+/+)鼠。这些结果表明，REG-REG受体系统对于小鼠的正常发育以及胰腺β细胞的复制都是必不可少的。

Reg (Regenerating gene) gene encodes a secretory protein that induces pancreatic 13-cell proliferation as an autocrine/paracrine growth factor via Reg receptor (RegR). Accumulating in vitro and in vivo evidence- including that using Reg transgenic and Reg^</-> mice suggest that Reg protein is also involved in regenerative cell proliferation in a variety of tissues such as gastrointestinal, neural and cardiovascular cells. Here, we produced mice with a targeted disruption of RegR to investigate the impact of the Reg-Reg receptor system in tissue regeneration and development. The heterozygous mutant mice (RegR^<+/-> had normal fertility and lifespans and maintained similar body weight and blood glucose level to those of their wild-type cohorts. In addition, there was no difference in pancreatic β-cell mass between RegR^<+/-> mice and the wild type whereas the mRNA and protein levels of RegR in the tissues of RegR^<+/-> mice were about half of the wild type. We then intercrossed RegR^<+/-> mice and found the total absence of RegR^(+/-) pups, indicating that this genotype is embryonic lethal. Timed pregnancies of heterozygotes revealed that RegR^(+/-) die between 8.5 and 9.5 days post coitum. As Reg^(+/-) mice showed the decreased β-cell regenerating activity, we induced pancreatic β-cell replication by partial pancreatectomy in RegR^<+/-> mice. Both the BrdU incorporation and the PCNA positive cells in pancreatic β-cells of RegR^(+/-) mice were decreased compared to those of RegR^(+/+) mice after surgery. These results indicate that the Reg-Reg receptor system is essential for normal mouse development as well as for replication of pancreatic β-cells.