Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
Pediatr Res. 2011 Jul;70(1):83-9. doi: 10.1203/PDR.0b013e31821bdf1c.
Our previous studies using puromycin aminonucleoside (PAN) established that podocyte damage leads to glomerular growth arrest during development and glomerulosclerosis later in life. This study examined the potential benefit of maintaining podocyte-derived VEGF in podocyte defense and survival after PAN injury using conditional transgenic podocytes and mice, in which human VEGF-A (hVEGF) transgene expression is controlled by tetracycline responsive element (TRE) promoter and reverse tetracycline transactivator (rtTA) in podocytes. In vitro experiments used primary cultured podocytes harvested from mice carrying podocin-rtTA and TRE-hVEGF transgenes, in which hVEGF can be induced selectively. Induction of VEGF in PAN-exposed podocytes resulted in preservation of intrinsic VEGF, α-actinin-4 and synaptopodin, antiapoptotic marker Bcl-xL/Bax, as well as attenuation in apoptotic marker cleaved/total caspase-3. In vivo, compared with genotype controls, PAN-sensitive neonatal mice with physiologically relevant levels of podocyte-derived VEGF showed significantly larger glomeruli. Furthermore, PAN-induced up-regulation of desmin, down-regulation of synaptopodin and nephrin, and disruption of glomerular morphology were significantly attenuated in VEGF-induced transgenic mice. Our data indicate that podocyte-derived VEGF provides self-preservation functions, which can rescue the cell after injury and preempt subsequent deterioration of the glomerulus in developing mice.
我们之前的研究使用嘌呤霉素氨基核苷（PAN）建立了这样的观点，即足细胞损伤导致肾小球在发育过程中生长停止，而在生命后期则导致肾小球硬化。本研究使用条件性转基因足细胞和小鼠，研究了在 PAN 损伤后维持足细胞源性 VEGF 对足细胞防御和存活的潜在益处，在这些转基因动物中，人 VEGF-A（hVEGF）的转基因表达受四环素反应元件（TRE）启动子和足细胞中的反向四环素转录激活因子（rtTA）控制。体外实验使用从小鼠中分离出的原代培养的足细胞进行，这些小鼠携带 podocin-rtTA 和 TRE-hVEGF 转基因，其中 hVEGF 可以被选择性诱导。在 PAN 暴露的足细胞中诱导 VEGF 表达导致内源性 VEGF、α-辅肌动蛋白-4 和突触蛋白保留，抗凋亡标志物 Bcl-xL/Bax 增加，以及凋亡标志物 cleaved/total caspase-3 减少。在体内，与基因型对照相比，具有生理相关水平的足细胞源性 VEGF 的 PAN 敏感新生小鼠具有明显更大的肾小球。此外，在 VEGF 诱导的转基因小鼠中，PAN 诱导的波形蛋白上调、突触蛋白下调和足突缺失以及肾小球形态破坏明显减弱。我们的数据表明，足细胞源性 VEGF 提供了自我保护功能，可在损伤后挽救细胞，并防止发育中小鼠肾小球的后续恶化。
