Increased abundance of the adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain and leucine zipper motif (APPL1) in patients with obesity and type 2 diabetes: evidence for altered adiponectin signalling

• DOI: 10.1007/s00125-011-2173-x
• Publication Date: 2011-05-11T12:04:53Z
• Authors: R. M. Holmes; Z. Yi; E. De Filippis; R. Berria; S. Shahani; P. Sathyanarayana; V. Sherman; K. Fujiwara; C. Meyer; C. Christ-Roberts; H. Hwang; J. Finlayson; L. Q. Dong; L. J. Mandarino; M. Bajaj
• Keywords: Pleckstrin homology domain; Adiponectin receptor 1; Phosphotyrosine-binding domain

The adiponectin signalling pathway is largely unknown, but recently the adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain and leucine zipper motif (APPL1), has been shown to interact directly with receptor (ADIPOR)1. APPL1 present in C2C12 myoblasts mouse skeletal muscle, its presence human muscle not investigated. Samples from type 2 diabetic, lean non-diabetic obese participants were analysed by: immunoprecipitation western blot; HPLC-electrospray ionisation (ESI)-mass spectrometry (MS) analysis; peak area analysis by MS; HPLC-ESI-MS/MS/MS RT-PCR of mRNA. Immunoprecipitation blot indicated a band specific APPL1. Tryptic digestion HPLC-ESI-MS whole-muscle homogenate unambiguously identified 56% sequence coverage. Peak MS validated results, showing levels be significantly increased diabetic as compared participants. Targeted phosphopeptide showed that was phosphorylated specifically on Ser401. mRNA expression After bariatric surgery morbidly subsequent weight loss, abundance reduced (p < 0.05) association an increase plasma 0.01), ADIPOR1 AMP-activated kinase (AMPK) phosphorylation 0.05). higher muscle; vivo Improvements hyperglycaemia hypoadiponectinaemia following loss are associated APPL1, AMPK phosphorylation.