Rao Poornima, Roccisana Jennifer, Takane Karen K, Bottino Rita, Zhao Allan, Trucco Massimo, García-Ocaña Adolfo
Division of Endocrinology, BST-E-1140, University of Pittsburgh, 200 Lothrop St., Pittsburgh, PA 15261, USA.
Diabetes. 2005 Jun;54(6):1664-75. doi: 10.2337/diabetes.54.6.1664.
Akt is an important intracellular mediator of beta-cell growth and survival in rodents. However, whether constitutive activation of Akt in human beta-cells enhances the survival and function of transplanted islets is unknown. In the current study, we examined the efficacy of constitutive activation of Akt in improving human islet transplant outcomes using a marginal mass model in diabetic severe combined immunodeficient (SCID) mice. Human islets transduced with adenoviruses encoding constitutively active Akt1 (Adv-CA-Akt) displayed increased total and phosphorylated Akt and Akt kinase activity compared with control islets. Expression of CA-Akt in human islets induced a significant increase in beta-cell replication and a significant decrease in beta-cell death induced by serum and glucose deprivation or chronic hyperglycemia. Two control groups of islets (1,500 uninfected or adenovirus LacZ [Adv-LacZ]-transduced human islet equivalents [IEQs]) transplanted under the kidney capsule of streptozotocin-induced diabetic SCID mice were insufficient to correct hyperglycemia. Importantly and in marked contrast to these controls, 1,500 Adv-CA-Akt-transduced IEQs were capable of restoring euglycemia in diabetic SCID mice. Moreover, blood glucose normalization persisted for at least 6 months. Human plasma insulin at day 54 after transplant was 10-fold higher in Adv-CA-Akt islet recipients (2.4 +/- 0.4 ng/ml) compared with those receiving Adv-LacZ islets (0.25 +/- 0.08 ng/ml) (P < 0.05). In summary, expression of CA-Akt in human islets improves islet transplant outcomes in a subcapsular renal graft model in SCID mice. Akt is an attractive target for future strategies aimed at reducing the number of islets required for successful islet transplantation in humans.
Akt是啮齿动物胰岛β细胞生长和存活的重要细胞内介质。然而,Akt在人β细胞中的组成性激活是否能提高移植胰岛的存活和功能尚不清楚。在本研究中,我们使用糖尿病重症联合免疫缺陷(SCID)小鼠的边缘质量模型,研究了Akt组成性激活对改善人胰岛移植结果的效果。与对照胰岛相比,用编码组成性活性Akt1的腺病毒(Adv-CA-Akt)转导的人胰岛显示总Akt和磷酸化Akt增加,Akt激酶活性增强。CA-Akt在人胰岛中的表达导致β细胞复制显著增加,血清和葡萄糖剥夺或慢性高血糖诱导的β细胞死亡显著减少。将两组对照胰岛(1500个未感染或腺病毒LacZ [Adv-LacZ]转导的人胰岛当量[IEQ])移植到链脲佐菌素诱导的糖尿病SCID小鼠的肾被膜下,不足以纠正高血糖。重要的是,与这些对照形成鲜明对比的是,1500个Adv-CA-Akt转导的IEQ能够使糖尿病SCID小鼠恢复正常血糖。此外,血糖正常化持续至少6个月。移植后第54天,Adv-CA-Akt胰岛受体的人血浆胰岛素(2.4±0.4 ng/ml)比接受Adv-LacZ胰岛的受体(0.25±0.08 ng/ml)高10倍(P<0.05)。总之,CA-Akt在人胰岛中的表达改善了SCID小鼠肾被膜下移植模型中的胰岛移植结果。Akt是未来旨在减少人类成功胰岛移植所需胰岛数量的策略的一个有吸引力的靶点。