Regulation of Megalin and Clathrin-Mediated Endocytosis by Amp-Activated Protein Kinase

Abstract

<p>AMP-activated protein kinase (AMPK) is a metabolic stress sensor, activated at low ATP levels. Our previous studies found AMPK activation reduced cell surface β1-integrin levels which are regulated by clathrin-mediated endocytosis (CME), an internalization mechanism dependent on adaptor proteins and triggered by cytosolic motif of a protein. This indicates that metabolic stress influences expression of some cell surface proteins, likely as a result of AMPK signaling regulating endocytosis. Integrin and Megalin both contain Dab2 recruiting NPXY motif and may both be regulated through AMPK. I confirmed that AMPK activation increased Dab2 recruitment to clathrin structures at the cell surface but decreased when ARFGAP3 and Arf6 are silenced. Using a transgenic LLC-PK1 cell-line I was able to observe increased levels of miniMegalin on cell surface after AMPK stimulation. In conclusion, this work highlights AMPK regulation of endocytic membrane traffic and that it varies depending on the cell type.</p>