Posttranslational regulation of polycystin-2 protein expression as a novel mechanism of cholangiocyte reaction and repair from biliary damage.
Posttranslational regulation of polycystin-2 protein expression as a novel mechanism of cholangiocyte reaction and repair from biliary damage.
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DOI：
10.1002/hep.28138
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发表时间：
2015-12
期刊：
影响因子：
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通讯作者：
Strazzabosco M
中科院分区：
文献类型：
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作者：
Spirli C;Villani A;Mariotti V;Fabris L;Fiorotto R;Strazzabosco M
多囊蛋白-2（PC2/TRPP2）是瞬时受体电位通道（TRP）家族的成员，是一种非选择性钙通道。PC2/TRPP2突变与多囊肝疾病相关。PC2缺陷型胆管细胞显示cAMP产生增加、ERK 1/2通路的PKA依赖性激活、HIF 1 α介导的VEGF产生以及囊肿生长和进展的刺激。胆管细胞中ERK/HIF 1 α/VEGF通路的激活在胆道损伤修复过程中起关键作用。我们假设在胆管损伤/修复过程中PC2水平受到调节，导致ERK/HIF 1 α/VEGF通路的激活。在胆管损伤（Mdr2 −/−-KO，胆管结扎，DDC治疗）的小鼠肝脏中，PC2蛋白表达（而非其基因表达）显著降低。用促炎细胞因子、一氧化氮（NO）供体和ER应激物处理colangiocytes），增加ERK 1/2磷酸化、HIF 1 α转录活性、VEGF分泌、VEGFR2磷酸化和下调PC 2蛋白表达，而不影响PC 2基因表达。促进蛋白体PC2降解的泛素样蛋白Herp和NEK的表达增加。用蛋白酶体抑制剂MG-132预处理恢复了用细胞因子处理的细胞中PC 2的表达，但在用NO供体或ER应激物处理的细胞中没有。在这些条件下，通过干扰自噬途径来抑制PC2降解。用蛋白酶体抑制剂硼替佐米治疗DDC-小鼠和Mdr2 −/−-小鼠，恢复了PC 2的表达，并显著降低了小管反应、纤维化和p-ERK 1/2。总之，在响应胆道损伤，PC2的表达是调制post-conflictionally由蛋白酶体或自噬途径。PC2下调与ERK 1/2激活和HIF 1 α介导的VEGF分泌增加有关。能够恢复PC2表达并减少胆管反应和纤维化的治疗可能代表胆道疾病的新治疗方法。
Polycystin-2 (PC2 /TRPP2), a member of the transient receptor potential channels (TRP) family, is a non-selective calcium channel. Mutations in PC2/TRPP2 are associated with Polycystic Liver Diseases. PC2-defective cholangiocytes shows increased production of cAMP, PKA-dependent activation of the ERK1/2 pathway, HIF1α-mediated VEGF production, and stimulation of cyst growth and progression. Activation of the ERK/HIF1α/VEGF pathway in cholangiocytes plays a key role during repair from biliary damage. We hypothesized that PC2 levels are modulated during biliary damage/repair, resulting in activation of the ERK/HIF1α/VEGF pathway. PC2 protein expression, but not its gene expression, was significantly reduced in mouse livers with biliary damage (Mdr2−/−-KO, bile duct ligation, DDC-treatment). Treatment of colangiocytes with pro-inflammatory cytokines, nitric oxide (NO) donors and ER stressors), increased ERK1/2 phosphorylation, HIF1α transcriptional activity, secretion of VEGF, VEGFR2 phosphorylation and downregulated PC2 protein expression without affecting PC2 gene expression. Expression of Herp and NEK, ubiquitin-like proteins that promote proteosomal PC2 degradation was increased. Pre-treatment with the proteasome inhibitor MG-132 restored the expression of PC2 in cells treated with cytokines but not in cells treated with NO donors or with ER stressors. In these conditions, PC2 degradation was instead inhibited by interfering with the autophagy pathway. Treatment of DDC-mice and of Mdr2−/−-mice with the proteasome inhibitor bortezomib, restored PC2 expression and significantly reduced the ductular reaction, fibrosis and p-ERK1/2. In conclusion, in response to biliary damage, PC2 expression is modulated post-translationally by the proteasome or the autophagy pathways. PC2-dowregulation is associated with activation of ERK1/2 and increase of HIF1α-mediated VEGF secretion. Treatments able to restore PC2 expression and to reduce ductular reaction and fibrosis may represent a new therapeutic approach in biliary diseases.