Organ Transplantation Center, the First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan Province, China.
Organ Transplantation Center, the First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan Province, China.
Biochem Biophys Res Commun. 2021 Feb 12;540:42-50. doi: 10.1016/j.bbrc.2020.12.104. Epub 2021 Jan 12.
Liver sinusoidal endothelial cells (LSECs), which play a very critical role in liver regeneration, function in hypoxic environments, but few studies have elucidated the specific mechanism. As a hypoxia-sensitive gene, Sentrin/SUMO-specific protease 1(SENP1) is upregulated in solid tumors due to hypoxia and promotes tumor proliferation. We speculate that LSECs may upregulate SENP1 in hypoxic environments and that SENP1 may act on downstream genes to allow the cells to adapt to the hypoxic environment. To elucidate the reasons for the survival of LSECs under hypoxia, we designed experiments to explore the possible mechanism. First, we cultured murine LSECs in hypoxic conditions for a certain time (24 h and 72 h), and then, we observed that the proliferation ability of the hypoxia group was higher than that of the normoxia group, and the number of unique fenestrae of the LSECs in the hypoxia group was more than that of the LSECs in the normoxia group. Then, we divided the LSECs into several groups for hypoxic culture for time points (6 h, 12 h, 24 h, 36 h, and 72 h), and we found that the expression of SENP1, HIF-1α and VEGF was significantly upregulated. Then, we silenced SENP1 and HIF-1α with si-SENP1 and si-HIF-1α, respectively. SENP1, HIF-1α and VEGF were significantly downregulated, as determined by RT-PCR, WB and ELISA. Unexpectedly, the proliferation activity of the LSECs decreased and the fenestrae disappeared more in the si-SENP1 and si-HIF-1α groups than in the control group. It is concluded that LSECs cultured under hypoxic conditions may maintain fenestrae and promote proliferation through the SENP1/HIF-1α/VEGF signaling axis, thereby adapting to the hypoxic environment.
肝窦内皮细胞（LSECs）在肝再生中起着非常关键的作用，它们在低氧环境中发挥作用，但很少有研究阐明其具体机制。作为一种缺氧敏感基因，SENP1 在实体瘤中由于缺氧而上调，并促进肿瘤增殖。我们推测，LSECs 可能在低氧环境中上调 SENP1，SENP1 可能作用于下游基因，使细胞适应低氧环境。为了阐明 LSECs 在低氧环境下存活的原因，我们设计实验来探索可能的机制。首先，我们将鼠 LSECs 在低氧条件下培养一定时间（24 h 和 72 h），然后观察到低氧组的增殖能力高于常氧组，低氧组的 LSECs 的特有窗孔数量多于常氧组。然后，我们将 LSECs 分成几组进行低氧培养不同的时间点（6 h、12 h、24 h、36 h 和 72 h），我们发现 SENP1、HIF-1α 和 VEGF 的表达明显上调。然后，我们分别用 si-SENP1 和 si-HIF-1α 沉默 SENP1 和 HIF-1α。通过 RT-PCR、WB 和 ELISA 检测，发现 SENP1、HIF-1α 和 VEGF 的表达明显下调。出乎意料的是，si-SENP1 和 si-HIF-1α 组的 LSECs 增殖活性下降，窗孔消失比对照组更明显。综上所述，在低氧条件下培养的 LSECs 可能通过 SENP1/HIF-1α/VEGF 信号轴维持窗孔并促进增殖，从而适应低氧环境。
