Podocytes are lost from glomeruli before completing apoptosis
Podocytes are lost from glomeruli before completing apoptosis
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DOI：
10.1152/ajprenal.00080.2022
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发表时间：
2022-11-01
影响因子：
4.2
通讯作者：
Matsusaka，Taiji
中科院分区：
文献类型：
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作者：
Yamamoto，Kazuyoshi;Okabe，Masahiro;Matsusaka，Taiji
尽管足细胞凋亡在体外研究中已被广泛报道，但在体内情况下的报道较少。为了研究这种差异，我们使用LMB 2（一种人（h）CD 25定向免疫毒素）分析了足细胞在体外和体内的染色过程。LMB 2在2天内以半胱天冬酶-3、Bak 1和Bcl-2依赖性方式诱导56.8 ± 13.6%的表达hCD 25的培养足细胞死亡。LMB 2诱导典型的凋亡特征，包括TUNEL染色和无乳酸脱氢酶渗漏的碎裂核。在体内，LMB 2有效地消除了NEP 25小鼠中表达hCD 25的足细胞。由LMB 2损伤的足细胞偶尔被染色为裂解的半胱天冬酶-3和裂解的核纤层蛋白A，但从未被染色为TUNEL。尿沉渣含有TUNEL阳性足细胞。为了检查肾小球滤过的作用，我们在安乐死前1天在用LMB 2处理的NEP 25小鼠中进行单侧输尿管梗阻。梗阻侧肾小球中核纤层蛋白A阳性足细胞的比例显著高于对侧（50.1 ± 5.4%vs.29.3 ± 4.1%，P < 0.001）。为了进一步检查没有肾小球过滤的死亡过程，我们用LMB 2处理从NEP 25小鼠的肾单位祖细胞产生的肾类器官。足细胞显示TUNEL染色和核碎裂。这些结果表明，在激活凋亡半胱天冬酶，足细胞脱落，并在核碎裂之前丢失在尿中，肾小球过滤的物理力促进脱离。这种现象可能是为什么最终的凋亡是没有观察到在足细胞在vivo.NEW & NOTEWORTHThis报告澄清为什么形态学上确定的凋亡是没有观察到在足细胞在vivo。当caspase-3在足细胞中被激活时，这些细胞立即从肾小球分离，并在DNA片段化发生之前在尿液中丢失。肾小球滤过促进了分离。这一现象解释了为什么体内足细胞很少显示TUNEL染色，也从不显示凋亡小体。
Although apoptosis of podocytes has been widely reported in in vitro studies, it has been less frequently and less definitively documented in in vivo situations. To investigate this discrepancy, we analyzed the dying process of podocytes in vitro and in vivo using LMB2, a human (h)CD25-directed immunotoxin. LMB2 induced cell death within 2 days in 56.8 ± 13.6% of cultured podocytes expressing hCD25 in a caspase-3, Bak1, and Bax-dependent manner. LMB2 induced typical apoptotic features, including TUNEL staining and fragmented nuclei without lactate dehydrogenase leakage. In vivo, LMB2 effectively eliminated hCD25-expressing podocytes in NEP25 mice. Podocytes injured by LMB2 were occasionally stained for cleaved caspase-3 and cleaved lamin A but never for TUNEL. Urinary sediment contained TUNEL-positive podocytes. To examine the effect of glomerular filtration, we performed unilateral ureteral obstruction in NEP25 mice treated with LMB2 1 day before euthanasia. In the obstructed kidney, glomeruli contained significantly more cleaved lamin A-positive podocytes than those in the contralateral kidney (50.1 ± 5.4% vs. 29.3 ± 4.1%,P< 0.001). To further examine the dying process without glomerular filtration, we treated kidney organoids generated from nephron progenitor cells of NEP25 mice with LMB2. Podocytes showed TUNEL staining and nuclear fragmentation. These results indicate that on activation of apoptotic caspases, podocytes are detached and lost in the urine before nuclear fragmentation and that the physical force of glomerular filtration facilitates detachment. This phenomenon may be the reason why definitive apoptosis is not observed in podocytes in vivo.NEW & NOTEWORTHYThis report clarifies why morphologically definitive apoptosis is not observed in podocytes in vivo. When caspase-3 is activated in podocytes, these cells are immediately detached from the glomerulus and lost in the urine before DNA fragmentation occurs. Detachment is facilitated by glomerular filtration. This phenomenon explains why podocytes in vivo rarely show TUNEL staining and never apoptotic bodies.