Sousa-Filho Celso Pereira Batista, Petrovic Natasa
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
Mol Metab. 2025 May;95:102127. doi: 10.1016/j.molmet.2025.102127. Epub 2025 Mar 20.
Several recent studies have indicated the presence of UCP1 in the kidney, challenging the paradigm that UCP1 is only found in brown and beige adipocytes and broadening the (patho)physiological significance of UCP1. The kidney localization has been the direct result of immunohistochemical investigations and an inferred outcome from multiple lines of reporter mice. These findings require confirmation and further physiological characterization.
We examined UCP1 expression in the kidney using immunohistochemistry and qPCR. Transversal sections through or near the kidney hilum, consistently including perirenal brown fat and adjacent kidney tissue, were analyzed with four UCP1 antibodies.
In addition to detecting UCP1 in perirenal adipose tissue, we observed distinct immunopositive structures in the kidney with our in-house UCP1-antibody, 'C10', in apparent agreement with earlier reports. To corroborate this, we tested the C10-antibody on kidney sections from UCP1-ablated mice but found equal reactivity in these UCP1-negative tissues. We then tested the widely used antibody ab10983, previously employed in kidney studies. Also here, the positive signal persisted in UCP1-ablated mice, clearly invalidating earlier findings. UCP1 qPCR studies also failed to detect UCP1 mRNA above background. Finally, two highly specific antibodies, E9Z2V and EPR20381, accurately detected UCP1 in perirenal adipose tissue but showed no signal in the kidney.
When appropriate controls are implemented, there is no evidence for the presence of UCP1 in the kidney. Consequently, this conclusion also implies that the results from UCP1 reporter mice, specifically regarding kidney expression of the UCP1 gene - though possibly applicable to other tissues - require reconfirmation before being accepted as evidence for the presence of UCP1 in non-adipose tissues.
最近的几项研究表明肾脏中存在解偶联蛋白1（UCP1），这对UCP1仅存在于棕色和米色脂肪细胞中的范式提出了挑战，并拓宽了UCP1的（病理）生理意义。肾脏定位是免疫组织化学研究的直接结果，也是多条报告基因小鼠实验推断出的结果。这些发现需要得到证实并作进一步的生理学特征描述。
我们使用免疫组织化学和定量聚合酶链反应（qPCR）检测肾脏中UCP1的表达。用四种UCP1抗体分析通过肾门或肾门附近的横向切片，这些切片始终包括肾周棕色脂肪和相邻的肾脏组织。
除了在肾周脂肪组织中检测到UCP1外，我们用自制的UCP1抗体“C10”在肾脏中观察到明显的免疫阳性结构，这显然与早期报告一致。为了证实这一点，我们在UCP1基因敲除小鼠的肾脏切片上测试了C10抗体，但在这些UCP1阴性组织中发现了相同的反应性。然后，我们测试了在肾脏研究中广泛使用的抗体ab10983。同样，在UCP1基因敲除小鼠中阳性信号依然存在，这显然使早期的研究结果无效。UCP1的qPCR研究也未能在背景之上检测到UCP1信使核糖核酸（mRNA）。最后，两种高度特异性的抗体E9Z2V和EPR20381在肾周脂肪组织中准确检测到了UCP1，但在肾脏中未显示信号。
当采用适当的对照时，没有证据表明肾脏中存在UCP1。因此，这一结论还意味着，UCP1报告基因小鼠的结果，特别是关于UCP1基因在肾脏中的表达——尽管可能适用于其他组织——在被接受为非脂肪组织中存在UCP1的证据之前，需要重新确认。
