Functional Significance of Point Mutations in Stress Chaperone Mortalin and Their Relevance to Parkinson Disease

Wadhwa, Renu; Ryu, Jongseong; Ahn, Hyo Min; Saxena, Nishant; Chaudhary, Anupama; Yun, Chae Ok; Kaul, Sunil C.

doi:10.1074/jbc.m114.627463

Cited by 44 publications

(33 citation statements)

References 54 publications

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“…Although primary breast cancer is often treated with surgery and radiation, it is the later stage when cells escape treatment due to chemoresistance and metastasis to the brain, bones, liver, and lungs. Mortalin was shown to activate telomerase, hnRNP-K, E2F1A, and PI3K/AKT proteins (23,37,38). In agreement with these known functions of mortalin, it has been detected as an upregulated protein in a variety of human tumors.…”

Section: Discussionmentioning

confidence: 66%

“…FBS (10%) was placed in the bottom of Transwell chamber and the assembly was incubated at 37 C for 4 to 6 hours, fixed, and stained with hematoxylin and eosin (23). In vitro Matrigel invasion assays were performed using BD BioCoat Matrigel Invasion Chamber (BD Biosciences) following the manufacturer's instructions and as described previously (23).…”

Section: Migration and Invasion Assaymentioning

confidence: 99%

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Stress Chaperone Mortalin Contributes to Epithelial-to-Mesenchymal Transition and Cancer Metastasis

Kaul

Ryu

et al. 2016

Cancer Research

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Mortalin/mthsp70 (HSPA9) is a stress chaperone enriched in many cancers that has been implicated in carcinogenesis by promoting cell proliferation and survival. In this study, we examined the clinical relevance of mortalin upregulation in carcinogenesis. Consistent with high mortalin expression in various human tumors and cell lines, we found that mortalin overexpression increased the migration and invasiveness of breast cancer cells. Expression analyses revealed that proteins involved in focal adhesion, PI3K-Akt, and JAK-STAT signaling, all known to play key roles in cell migration and epithelial-tomesenchymal transition (EMT), were upregulated in mortalinexpressing cancer cells. We further determined that expression levels of the mesenchymal markers vimentin (VIM), fibronectin (FN1), b-catenin (CTNNB1), CK14 (KRT14), and hnRNP-K were also increased upon mortalin overexpression, whereas the epithelial markers E-cadherin (CDH1), CK8 (KRT8), and CK18 (KRT18) were downregulated. Furthermore, shRNAmediated and pharmacologic inhibition of mortalin suppressed the migration and invasive capacity of cancer cells and was associated with a diminished EMT gene signature. Taken together, these findings support a role for mortalin in the induction of EMT, prompting further investigation of its therapeutic value in metastatic disease models. Cancer Res; 76(9);

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Section: Discussionmentioning

confidence: 66%

Section: Migration and Invasion Assaymentioning

confidence: 99%

Stress Chaperone Mortalin Contributes to Epithelial-to-Mesenchymal Transition and Cancer Metastasis

Kaul

Ryu

et al. 2016

Cancer Research

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“…Hsp90 and its co‐chaperones regulate tau and Aβ processing (Blair et al ., 2014), and Hsp90 may specifically protect TDP‐43 from ROS‐induced aggregation (Chang et al ., 2013a). The mitochondrial HSP70, also called ‘stress‐70’ or ‘mortalin’, is implicated in PD and in vitro longevity (Wadhwa et al ., 2015). Lamin A mutants induce nuclear protein aggregation (Hubner et al ., 2006).…”

Section: Discussionmentioning

confidence: 99%

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls

et al. 2016

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SummaryNeurodegenerative diseases are distinguished by characteristic protein aggregates initiated by disease‐specific ‘seed’ proteins; however, roles of other co‐aggregated proteins remain largely unexplored. Compact hippocampal aggregates were purified from Alzheimer's and control‐subject pools using magnetic‐bead immunoaffinity pulldowns. Their components were fractionated by electrophoretic mobility and analyzed by high‐resolution proteomics. Although total detergent‐insoluble aggregates from Alzheimer's and controls had similar protein content, within the fractions isolated by tau or Aβ1–42 pulldown, the protein constituents of Alzheimer‐derived aggregates were more abundant, diverse, and post‐translationally modified than those from controls. Tau‐ and Aβ‐containing aggregates were distinguished by multiple components, and yet shared >90% of their protein constituents, implying similar accretion mechanisms. Alzheimer‐specific protein enrichment in tau‐containing aggregates was corroborated for individuals by three analyses. Five proteins inferred to co‐aggregate with tau were confirmed by precise in situ methods, including proximity ligation amplification that requires co‐localization within 40 nm. Nematode orthologs of 21 proteins, which showed Alzheimer‐specific enrichment in tau‐containing aggregates, were assessed for aggregation‐promoting roles in C. elegans by RNA‐interference ‘knockdown’. Fifteen knockdowns (71%) rescued paralysis of worms expressing muscle Aβ, and 12 (57%) rescued chemotaxis disrupted by neuronal Aβ expression. Proteins identified in compact human aggregates, bound by antibody to total tau, were thus shown to play causal roles in aggregation based on nematode models triggered by Aβ1–42. These observations imply shared mechanisms driving both types of aggregation, and/or aggregate‐mediated cross‐talk between tau and Aβ. Knowledge of protein components that promote protein accrual in diverse aggregate types implicates common mechanisms and identifies novel targets for drug intervention.

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“…Combining the computational study with the Y2H and His-tag pull-down assays indicates that UBXN2A binds to and occupies the mortalin binding pocket within the SBD domain. As previously described (Wadhwa et al 2015). there are individual amino acids within mortalin whose mutations can dramatically change mortalin functions, including alteration in mortalin binding partners.…”

Section: Molecular Modeling Of Mortalinmentioning

confidence: 89%

“…It has been suggested that CHIP binds to mortalin and mediates proteasomal degradation of selective substrates such as p53 (Kaul et al 2007). In fact, overexpression of mortalin decreases the protein level of p53 in U2OS cells (Wadhwa et al 2015). To test whether UBXN2A can inhibit mortalin/CHIP-dependent degradation of p53 in the cytoplasm, we transiently transfected HEK293T cells with (His) 6 -CHIP E3 ubiquitin ligase ± GFP-empty or GFP-UBXN2A (see BMaterial and methods^section).…”

Section: Molecular Modeling Of Mortalinmentioning

confidence: 99%

Structural studies of UBXN2A and mortalin interaction and the putative role of silenced UBXN2A in preventing response to chemotherapy

Sane

Abdullah

Nelson

et al. 2016

Cell Stress and Chaperones

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Overexpression of the oncoprotein mortalin in cancer cells and its protein partners enables mortalin to promote multiple oncogenic signaling pathways and effectively antagonize chemotherapy-induced cell death. A UBX-domaincontaining protein, UBXN2A, acts as a potential mortalin inhibitor. This current study determines whether UBXN2A effectively binds to and occupies mortalin's binding pocket, resulting in a direct improvement in the tumor's sensitivity to chemotherapy. Molecular modeling of human mortalin's binding pocket and its binding to the SEP domain of UBXN2A followed by yeast two-hybrid and His-tag pulldown assays revealed that three amino acids (PRO442, ILE558, and LYS555) within the substrate-binding domain of mortalin are crucial for UBXN2A binding to mortalin. As revealed by chase experiments in the presence of cycloheximide, overexpression of UBXN2A seems to interfere with the mortalin-CHIP E3 ubiquitin ligase and consequently suppresses the C-terminus of the HSC70-interacting protein (CHIP)-mediated destabilization of p53, resulting in its stabilization in the cytoplasm and upregulation in the nucleus. Overexpression of UBXN2A causes a significant inhibition of cell proliferation and the migration of colon cancer cells. We silenced UBXN2A in the human osteosarcoma U2OS cell line, an enriched mortalin cancer cell, followed by a clinical dosage of the chemotherapeutic agent 5-fluorouracil (5-FU). The UBXN2A knockout U2OS cells revealed that UBXNA is essential for the cytotoxic effect achieved by 5-FU. UBXN2A overexpression markedly increased the apoptotic response of U2OS cells to the 5-FU. In addition, silencing of UBXN2A protein suppresses apoptosis enhanced by UBXN2A overexpression in U2OS. The knowledge gained from this study provides insights into the mechanistic role of UBXN2A as a potent mortalin inhibitor and as a potential chemotherapy sensitizer for clinical application.

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Functional Significance of Point Mutations in Stress Chaperone Mortalin and Their Relevance to Parkinson Disease

Cited by 44 publications

References 54 publications

Stress Chaperone Mortalin Contributes to Epithelial-to-Mesenchymal Transition and Cancer Metastasis

Stress Chaperone Mortalin Contributes to Epithelial-to-Mesenchymal Transition and Cancer Metastasis

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls

Structural studies of UBXN2A and mortalin interaction and the putative role of silenced UBXN2A in preventing response to chemotherapy

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