Kaverina Natalya V, Eng Diana G, Schneider Remington R S, Pippin Jeffrey W, Shankland Stuart J
Division of Nephrology, University of Washington, Seattle, Washington.
Division of Nephrology, University of Washington, Seattle, Washington
Am J Physiol Renal Physiol. 2016 Jun 1;310(11):F1397-413. doi: 10.1152/ajprenal.00369.2015. Epub 2016 Apr 13.
The current studies used genetic fate mapping to prove that adult podocytes can be partially replenished following depletion. Inducible NPHS2-rtTA/tetO-Cre/RS-ZsGreen-R reporter mice were generated to permanently label podocytes with the ZsGreen reporter. Experimental focal segmental glomerulosclerosis (FSGS) was induced with a cytotoxic podocyte antibody. On FSGS day 7, immunostaining for the podocyte markers p57, synaptopodin, and podocin were markedly decreased by 44%, and this was accompanied by a decrease in ZsGreen fluorescence. The nuclear stain DAPI was absent in segments of reduced ZsGreen and podocyte marker staining, which is consistent with podocyte depletion. Staining for p57, synaptopodin, podocin, and DAPI increased at FSGS day 28 and was augmented by the ACE inhibitor enalapril, which is consistent with a partial replenishment of podocytes. In contrast, ZsGreen fluorescence did not return and remained significantly low at day 28, indicating replenishment was from a nonpodocyte origin. Despite administration of bromodeoxyuridine (BrdU) thrice weekly throughout the course of disease, BrdU staining was not detected in podocytes, which is consistent with an absence of proliferation. Although ZsGreen reporting was reduced in the tuft at FSGS day 28, labeled podocytes were detected along the Bowman's capsule in a subset of glomeruli, which is consistent with migration from the tuft. Moreover, more than half of the migrated podocytes coexpressed the parietal epithelial cell (PEC) proteins claudin-1, SSeCKS, and PAX8. These results show that although podocytes can be partially replenished following abrupt depletion, a process augmented by ACE inhibition, the source or sources are nonpodocyte in origin and are independent of proliferation. Furthermore, a subset of podocytes migrate to the Bowman's capsule and begin to coexpress PEC markers.
目前的研究使用基因命运图谱来证明，成年足细胞在耗竭后可得到部分补充。构建了可诱导的NPHS2-rtTA/tetO-Cre/RS-ZsGreen-R报告基因小鼠，用ZsGreen报告基因永久标记足细胞。用细胞毒性足细胞抗体诱导实验性局灶节段性肾小球硬化（FSGS）。在FSGS第7天，足细胞标志物p57、突触素和足动蛋白的免疫染色显著降低了44%，同时ZsGreen荧光也降低。在ZsGreen和足细胞标志物染色减少的节段中没有核染色DAPI，这与足细胞耗竭一致。在FSGS第28天，p57、突触素、足动蛋白和DAPI的染色增加，血管紧张素转换酶抑制剂依那普利可增强这种增加，这与足细胞的部分补充一致。相比之下，ZsGreen荧光在第28天没有恢复，仍然显著较低，表明补充来自非足细胞来源。尽管在疾病过程中每周三次给予溴脱氧尿苷（BrdU），但在足细胞中未检测到BrdU染色，这与缺乏增殖一致。虽然在FSGS第28天，肾小球毛细血管袢中ZsGreen报告基因减少，但在一部分肾小球的鲍曼囊周围检测到标记的足细胞，这与从毛细血管袢迁移一致。此外，超过一半的迁移足细胞共表达壁层上皮细胞（PEC）蛋白claudin-1、SSeCKS和PAX8。这些结果表明，虽然足细胞在突然耗竭后可以得到部分补充，这一过程可通过ACE抑制增强，但补充来源是非足细胞来源，且与增殖无关。此外，一部分足细胞迁移到鲍曼囊并开始共表达PEC标志物。
