Unique integrated stress response sensors regulate cancer cell susceptibility when Hsp70 activity is compromised
Abstract
AMPK, AMP-activated protein Kinase; AKT, AK strain Transforming serine/threonine kinase; ASNS, asparagine synthetase; ATF4, activating transcription factor 4; ATF6, activating transcription factor 6; BiP, Immunoglobulin Binding Protein; CHOP, C/EBP homologous protein; CQ, chloroquine; DTT, 1,4-Dithiothreitol; EBSS, Earle's balanced salt solution; eIF2α, eukaryotic initiation factor 2 alpha; ER, endoplasmic reticulum; ERAD, endoplasmic reticulum associated degradation; FBS, fetal bovine serum; GCN2, general control non-derepressible 2 factor; GFP, green fluorescent protein; HER2, epidermal growth factor receptor 2; HIF1α, Hypoxia Inducible Factor 1 Subunit Alpha; HRI, heme-regulated inhibitor kinase; Hsp70, heat shock protein 70; IRE1, inositol-required enzyme 1; ISR, integrated stress response; MAL3-101, phenylmethyl 4-[1,1'-biphenyl]-4-yl-1-[6-[[2-(butylamino)-1-[3-(methoxycarbonyl)-4-(2-methoxy-2-oxoethoxy)phenyl]-2-oxoethyl]hexylamino]-6-oxohexyl]-1,2,3,4-tetrahydro-6-methyl-2-oxo-5-pyrimidinecarboxylate; mTOR, mechanistic Target Of Rapamycin; PBS, phosphate buffered saline; PERK, PKR-like endoplasmic reticulum resident kinase; PI, propidium iodide; PKR, Protein Kinase RNA-activated; RFP, red fluorescent protein; RPPA, Reverse Phase Protein Array; S6K, 70‐kDa ribosomal protein S6 kinase; TNBC, triple negative breast cancer; UPR, unfolded protein response; XbpI, X-box binding protein 1.
Data availability
All data generated or analysed during this study are included in the manuscript and source files.
Article and author information
Author details
Funding
European Molecular Biology Laboratory (post-doctoral fellowship (ALTF 823-2016))
- Sara Sannino
National Institutes of Health (F30CA250167)
- Megan E Yates
National Institutes of Health (GM131732)
- Jeffrey L Brodsky
National Institutes of Health (DK79307)
- Jeffrey L Brodsky
National Institutes of Health (P30CA047904)
- Jeffrey L Brodsky
Howard Hughes Medical Institute (Howard Hughes Medical Institute Collaborative Innovation award)
- Jeffrey L Brodsky
University of Pittsburgh (Translational and Precision Pharmacology programs (pilot grant))
- Jeffrey L Brodsky
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Franz-Ulrich Hartl, Max Planck Institute for Biochemistry, Germany
Version history
- Received: November 18, 2020
- Accepted: June 27, 2021
- Accepted Manuscript published: June 28, 2021 (version 1)
- Accepted Manuscript updated: June 29, 2021 (version 2)
- Version of Record published: July 12, 2021 (version 3)
Copyright
© 2021, Sannino et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Further reading
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A functional nervous system is built upon the proper morphogenesis of neurons to establish the intricate connection between them. The microtubule cytoskeleton is known to play various essential roles in this morphogenetic process. While many microtubule-associated proteins (MAPs) have been demonstrated to participate in neuronal morphogenesis, the function of many more remains to be determined. This study focuses on a MAP called HMMR in mice, which was originally identified as a hyaluronan binding protein and later found to possess microtubule and centrosome binding capacity. HMMR exhibits high abundance on neuronal microtubules and altering the level of HMMR significantly affects the morphology of neurons. Instead of confining to the centrosome(s) like cells in mitosis, HMMR localizes to microtubules along axons and dendrites. Furthermore, transiently expressing HMMR enhances the stability of neuronal microtubules and increases the formation frequency of growing microtubules along the neurites. HMMR regulates the microtubule localization of a non-centrosomal microtubule nucleator TPX2 along the neurite, offering an explanation for how HMMR contributes to the promotion of growing microtubules. This study sheds light on how cells utilize proteins involved in mitosis for non-mitotic functions.
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- Biochemistry and Chemical Biology
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Transport and localization of melanosome at the periphery region of melanocyte are depended on myosin-5a (Myo5a), which associates with melanosome by interacting with its adaptor protein melanophilin (Mlph). Mlph contains four functional regions, including Rab27a-binding domain, Myo5a GTD-binding motif (GTBM), Myo5a exon F-binding domain (EFBD), and actin-binding domain (ABD). The association of Myo5a with Mlph is known to be mediated by two specific interactions: the interaction between the exon-F-encoded region of Myo5a and Mlph-EFBD and that between Myo5a-GTD and Mlph-GTBM. Here, we identify a third interaction between Myo5a and Mlph, that is, the interaction between the exon-G-encoded region of Myo5a and Mlph-ABD. The exon-G/ABD interaction is independent from the exon-F/EFBD interaction and is required for the association of Myo5a with melanosome. Moreover, we demonstrate that Mlph-ABD interacts with either the exon-G or actin filament, but cannot interact with both of them simultaneously. Based on above findings, we propose a new model for the Mlph-mediated Myo5a transportation of melanosomes.