Cover Story Current Issue
At the turn of the 19th century, Ivan Pavlov and others established that the secretion of pancreatic juice is induced upon entry of acidic chyme into the duodenum, and that this pancreatic secretion is accelerated by infusion of hydrochloric acid (HCL) into the stomach. Pavlov hypothesized that secretion of pancreatic juice is induced via a neuronal reflex; however, pancreatic secretion prevailed in dogs following denervation of the intestinal vagal and splanchnic nerves, indicating that pancreatic secretion must be mediated by another, as yet unknown, mechanism.
Current Issue
No UCP1 in the kidney
No UCP1 in the kidney
Objectives
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.
Methods
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.
Results
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.
Conclusions
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.
Articles in Press
No UCP1 in the kidney
No UCP1 in the kidney
Objectives
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.
Methods
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.
Results
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.
Conclusions
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.
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You are what you eat
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