Biology subjects

Hatch, S. B.

Publications and source records attributed to Hatch, S. B..

4 recordsLinked to original sources

bioRxiv2021

Small molecule screen employing patient-derived iPS hepatocytes identifies LRRK2 as a novel therapeutic target for Alpha1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency is a life-threatening condition caused by inheritance of the SERPINA1 gene Z variant. This single base pair mutation leads to protein misfolding, ER entrapment and gain of toxic function. Despite the significant unmet medical need presented by this disorder, there remain no approved medicines and the only curative option is liver transplantation. We hypothesized that an unbiased screen of human hepatocytes harbouring the Z mutation (ATZ) using small molecules targeted against protein degradation pathways would uncover novel biological insights of therapeutic relevance. Here we report the results of that screen performed in a patient-derived iPSC model of ATZ. Starting from 1,041 compounds we identified 14 targets capable of reducing polymer burden, including Leucine-rich repeat kinase-2 (LRRK2), a well-studied target in Parkinsons. Genetic deletion of LRRK2 in ATZ mice reduced polymers and associated fibrotic liver disease leading us to test a library of commercially available LRRK2 kinase inhibitors in both patient iPSC and CHO cell models. One of the molecules tested, CZC-25146, reduced polymer load, increased normal AAT secretion and reduced inflammatory cytokines with pharmacokinetic properties supporting its potential use for treating liver diseases. We therefore tested CZC-25146 in the ATZ mouse model and confirmed its efficacy for polymer reduction without signs of toxicity. Mechanistically, in both human and mouse models, our data show CZC-25146 inhibits LRRK2 kinase activity and induces autophagy. Cumulatively, these findings support the use of CZC-25146 and LRRK2 inhibitors in general in hepatic proteopathy disease research and as potential new treatment approaches for patients. One Sentence SummaryA small molecule screen in patient iPSCs with in vivo validation in mice identifies LRRK2 as a new therapeutic target for Alpha-1 Antitrypsin Deficiency.

cell biology↗

bioRxiv2020

IGF targeting perturbs global replication through ribonucleotide reductase dysfunction

IGF receptor (IGF-1R) inhibition delays repair of radiation-induced DNA double-strand breaks (DSBs), prompting us to investigate whether IGF-1R influences endogenous DNA damage. We demonstrate that IGF-1R inhibition generates endogenous DNA lesions protected by 53BP1 bodies, indicating under-replicated DNA. We detect delayed replication fork progression in IGF-inhibited or IGF-1R depleted cancer cells, with activation of ATR-CHK1 signaling and the intra-S-phase checkpoint. This phenotype reflects unanticipated regulation of global replication by IGF-1, mediated via AKT, MEK/ERK and JUN to influence expression of ribonucleotide reductase (RNR) subunit RRM2. IGF-1R inhibition or depletion downregulate RRM2, compromising RNR function and dNTP supply. The resulting delay in fork progression and hallmarks of replication stress are rescued by RRM2 overexpression, confirming RRM2 as the critical factor through which IGF-1 regulates replication. Following targeted compound screens, we identify synergy between IGF inhibition and ATM loss, with evidence that IGF inhibition compromises growth of ATM null cells and xenografts. This synthetic lethal effect reflects conversion of single-stranded lesions in IGF-inhibited cells into toxic DSBs upon ATM inhibition. These data implicate IGF-1R in alleviating replication stress, and the identified reciprocal IGF:ATM co-dependence provides an approach to exploit this effect in ATM-deficient cancers.

cancer biology↗

bioRxiv2019

The Kinase Chemogenomic Set (KCGS): An open science resource for kinase vulnerability identification

We describe the assembly and annotation of a chemogenomic set of protein kinase inhibitors as an open science resource for studying kinase biology. The set only includes inhibitors that show potent kinase inhibition and a narrow spectrum of activity when screened across a large panel of kinase biochemical assays. Currently, the set contains 187 inhibitors that cover 215 human kinases. The kinase chemogenomic set (KCGS) is the most highly annotated set of selective kinase inhibitors available to researchers for use in cell-based screens.

cell biology↗

bioRxiv2019

Cyclin F-Chk1 synthetic lethality mediated by E2F1 degradation

Cyclins are central engines of cell cycle progression when partnered with Cyclin Dependent Kinases (CDKs). Among the different cyclins controlling cell cycle progression, cyclin F does not partner with a CDK, but forms an E3 ubiquitin ligase, assembling through the F-box domain, an Skp1-Cul1-F-box (SCF) module. Although multiple substrates of cyclin F have been identified the vulnerabilities of cells lacking cyclin F are not known. Thus, we assessed viability of cells lacking cyclin F upon challenging cells with more than 200 kinase inhibitors. The screen revealed a striking synthetic lethality between Chk1 inhibition and cyclin F loss. Chk1 inhibition in cells lacking cyclin F leads to DNA replication catastrophe. The DNA replication catastrophe depends on the accumulation of E2F1 in cyclin F depleted cells. We observe that SCFcyclin F promotes E2F1 degradation after Chk1 inhibitors in a CDK dependent manner. Thus, Cyclin F restricts E2F1 activity during cell cycle and upon checkpoint inhibition to prevent DNA replication stress. Our findings pave the way for patient selection in the clinical use of checkpoint inhibitors.

cancer biology↗