Abstract
The microtubule-associated protein, doublecortin-like kinase 1 (DCLK1), is highly expressed in a range of cancers and is a prominent therapeutic target for kinase inhibitors. The physiological roles of DCLK1 kinase activity and how it is regulated remain elusive. Here, we analyze the role of mammalian DCLK1 kinase activity in regulating microtubule binding. We found that DCLK1 autophosphorylates a residue within its C-terminal tail to restrict its kinase activity and prevent aberrant hyperphosphorylation within its microtubule-binding domain. Removal of the C-terminal tail or mutation of this residue causes an increase in phosphorylation within the doublecortin domains, which abolishes microtubule binding. Therefore, autophosphorylation at specific sites within DCLK1 has diametric effects on the molecule's association with microtubules. Our results suggest a mechanism by which DCLK1 modulates its kinase activity to tune its microtubule-binding affinity. These results provide molecular insights for future therapeutic efforts related to DCLK1's role in cancer development and progression.
Highlights
Growth is an essential process of life
The architecture of doublecortin-like kinase 1 (DCLK1) suggests it likely has the flexibility to autophosphorylate its N-terminal half due to an intrinsically disordered region between the DC2 domain and the kinase domain (Figure 3C, aa 263-374). These results indicate that the loss of microtubule binding of DCLK1- C is due to an increase in phosphorylation at multiple sites, as opposed to a single site whose phosphorylation status dictates microtubule binding
We have found that DCLK1 autophosphorylates within its C-terminal tail to prevent aberrant hyper-phosphorylation within its microtubule-binding domain
Summary
Growth is an essential process of life. Unchecked cellular growth, is a hallmark of cancer. Many studies have focused on developing small molecule inhibitors against DCLK1 kinase activity in an effort to control cancer growth [15,16,17] It is currently unclear if DCLK1 kinase activity, microtubule-binding activity, or both are involved in the molecule’s functions during cell division. Our data lead to a model in which DCLK1 autophosphorylates its C-terminal tail to modulate the activity of its own kinase domain and subsequently the level of phosphorylation within its microtubule-binding domains. To our knowledge, this is the first example of a self-regulatory MAP that can tune its microtubule-binding properties based on autophosphorylation state. Our results uncover a novel intramolecular regulation of microtubule binding within a prominent family of MAPs and may have implications for DCLK1’s known roles in tumor development and cancer progression
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