Neurolysin Knockout Mice Generation and Initial Phenotype Characterization

Diogo M.L.P Cavalcanti,Leandro M Castro,José C Rosa Neto,Marilia Seelaender,Rodrigo X Neves,Vitor Oliveira,Fábio L Forti,Leo K Iwai,Fabio C Gozzo,Mihail Todiras,Ines Schadock,Carlos C Barros,Michael Bader,Emer S Ferro

doi:10.1074/jbc.m113.539148

Abstract

The oligopeptidase neurolysin (EC 3.4.24.16; Nln) was first identified in rat brain synaptic membranes and shown to ubiquitously participate in the catabolism of bioactive peptides such as neurotensin and bradykinin. Recently, it was suggested that Nln reduction could improve insulin sensitivity. Here, we have shown that Nln KO mice have increased glucose tolerance, insulin sensitivity, and gluconeogenesis. KO mice have increased liver mRNA for several genes related to gluconeogenesis. Isotopic label semiquantitative peptidomic analysis suggests an increase in specific intracellular peptides in gastrocnemius and epididymal adipose tissue, which likely is involved with the increased glucose tolerance and insulin sensitivity in the KO mice. These results suggest the exciting new possibility that Nln is a key enzyme for energy metabolism and could be a novel therapeutic target to improve glucose uptake and insulin sensitivity.

Highlights

Neurolysin is known to cleave several bioactive peptides in vitro
Global analysis of intracellular peptides profile in soleus, gastrocnemius, liver, and epididymal adipose tissue quantified by LC-ESI-MS as Nln substrate, product, or neither substrate or product
The percentages indicate the amounts of intracellular peptides that are substrates, products, or not cleaved by Nln (n ϭ 5)

Summary

Introduction

Results: Neurolysin knock-out mice showed increased glucose tolerance, insulin sensitivity, and gluconeogenesis, which likely relates to increased expression of both specific liver mRNAs and intracellular peptides. We have shown that Nln KO mice have increased glucose tolerance, insulin sensitivity, and gluconeogenesis. Isotopic label semiquantitative peptidomic analysis suggests an increase in specific intracellular peptides in gastrocnemius and epididymal adipose tissue, which likely is involved with the increased glucose tolerance and insulin sensitivity in the KO mice. These results suggest the exciting new possibility that Nln is a key enzyme for energy metabolism and could be a novel therapeutic target to improve glucose uptake and insulin sensitivity

Results

Discussion

Conclusion