Amino acid residues critical for anaplastic lymphoma kinase receptor cleavage

Abstract

The overexpression and phosphorylation of the wild type Anaplastic Lymphoma Kinase (ALK) receptor in neuroblastoma has been associated with a worse prognosis for patients suffering from high risk neuroblastoma. Recent evidence has shown that truncated forms of the ALK receptor may be capable of promoting downstream pathways associated with ALK activation and increased cellular proliferation. ALK has been shown to cleave into 220kDa and 140kDa bands in vivo, but the exact location of the cleavage site within the ALK protein has not yet been characterized. By generating amino acid substitutions around the putative cleavage site of ALK, we sought to determine if we could inhibit ALK cleavage. We were able to significantly inhibit cleavage through substitutions in amino acids L655 and F656 surrounding our predicted cleavage site. These amino acids may potentially play a critical role in enzymatic identification of the ALK cleavage site and mediating ALK cleavage. Future studies are necessary in order to determine if ALK constructs with three amino acid substitutions around the cleavage site will show complete ALK cleavage inhibition and determine the relationship between ALK cleavage and activation of downstream pathways.