A Nuclear Phosphatase-Kinase Signaling Complex That Supports Acute Myeloid Leukemia

Polyanskaya, Sofya A (July 2020) A Nuclear Phosphatase-Kinase Signaling Complex That Supports Acute Myeloid Leukemia. PhD thesis, Cold Spring Harbor Laboratory.

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Abstract

Acute myeloid leukemia (AML) cells rely on phospho-signaling pathways to gain unlimited proliferation potential. A tightly regulated balance between phosphorylation and dephosphorylation, sustained by coordinated and competing activities of phosphatases and kinases, lies at the basis of cellular signaling. Given the advances of the past two decades in designing potent and selective inhibitors against phosphatases and kinases, these phosphosignaling enzymes present some of the priority targets in AML. Here, we used domain-focused CRISPR screening to identify the nuclear phosphatase SCP4 as a dependency in AML. We provide evidence that this enzyme is likely dispensable in normal hematopoietic progenitor cells and could constitute a novel therapeutic target in leukemia. Using CRISPR exon scanning and gene complementation assays, we showed that the catalytic function of SCP4 was essential in AML. Our work, for the first time, elucidates a link between SCP4 and human cancer and provides a context for a deeper understanding of the molecular functions of this poorly studied phosphatase. Through mass spectrometry analysis of the SCP4 interactome, we identify the kinase paralogs STK35 and PDIK1L as binding partners and substrates of the SCP4 phosphatase domain. STK35/PDIK1L signaling roles and biochemical interactions are largely unknown, and this study sheds light on their involvement in leukemogenesis. We showed that STK35 and PDIK1L catalytic activity was required in AML. Moreover, these kinases function redundantly in the same pathway as SCP4 to maintain leukemia cell proliferation. We found that SCP4 regulated STK35/PDIK1L through two distinct mechanisms: promoting kinase stability and kinase catalytic activity. Our study provides the first genetic evidence that the conserved serine residue at the DFG+2 position could serve as the site of inhibitory phosphorylation at the kinases activation loop. Overall, our findings reveal a novel phosphatase-kinase signaling complex that supports the pathogenesis of AML.

Item Type:	Thesis (PhD)
Subjects:	bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > SCP4 diseases & disorders > cancer > cancer types > acute myeloid leukemia Investigative techniques and equipment > CRISPR-Cas9 bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > kinase bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > PDIK1L bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein phosphatase bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > STK35
CSHL Authors:	Polyanskaya, Sofya
Communities:	CSHL labs > Vakoc lab School of Biological Sciences > Theses
Depositing User:	Sasha Luks-Morgan
Date:	25 July 2020
Date Deposited:	01 Sep 2021 13:34
Last Modified:	01 Sep 2021 13:34
URI:	https://repository.cshl.edu/id/eprint/40336

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