1
|
Mahalingan KK, Grotjahn DA, Li Y, Lander GC, Zehr EA, Roll-Mecak A. Structural basis for α-tubulin-specific and modification state-dependent glutamylation. Nat Chem Biol 2024:10.1038/s41589-024-01599-0. [PMID: 38658656 DOI: 10.1038/s41589-024-01599-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 03/06/2024] [Indexed: 04/26/2024]
Abstract
Microtubules have spatiotemporally complex posttranslational modification patterns. Tubulin tyrosine ligase-like (TTLL) enzymes introduce the most prevalent modifications on α-tubulin and β-tubulin. How TTLLs specialize for specific substrate recognition and ultimately modification-pattern generation is largely unknown. TTLL6, a glutamylase implicated in ciliopathies, preferentially modifies tubulin α-tails in microtubules. Cryo-electron microscopy, kinetic analysis and single-molecule biochemistry reveal an unprecedented quadrivalent recognition that ensures simultaneous readout of microtubule geometry and posttranslational modification status. By binding to a β-tubulin subunit, TTLL6 modifies the α-tail of the longitudinally adjacent tubulin dimer. Spanning two tubulin dimers along and across protofilaments (PFs) ensures fidelity of recognition of both the α-tail and the microtubule. Moreover, TTLL6 reads out and is stimulated by glutamylation of the β-tail of the laterally adjacent tubulin dimer, mediating crosstalk between α-tail and β-tail. This positive feedback loop can generate localized microtubule glutamylation patterns. Our work uncovers general principles that generate tubulin chemical and topographic complexity.
Collapse
Affiliation(s)
- Kishore K Mahalingan
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Danielle A Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute La Jolla, La Jolla, CA, USA
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute La Jolla, La Jolla, CA, USA
| | - Elena A Zehr
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
- Biochemistry & Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA.
| |
Collapse
|
2
|
Arabkari V, Barua D, Hossain MM, Webber M, Smith T, Gupta A, Gupta S. miRNA-378 Is Downregulated by XBP1 and Inhibits Growth and Migration of Luminal Breast Cancer Cells. Int J Mol Sci 2023; 25:186. [PMID: 38203358 PMCID: PMC10778669 DOI: 10.3390/ijms25010186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/13/2023] [Accepted: 12/16/2023] [Indexed: 01/12/2024] Open
Abstract
X-box binding protein 1 (XBP1) is a transcription factor that plays a crucial role in the unfolded protein response (UPR), a cellular stress response pathway involved in maintaining protein homeostasis in the endoplasmic reticulum (EnR). While the role of XBP1 in UPR is well-characterised, emerging evidence suggests its involvement in endocrine resistance in breast cancer. The transcriptional activity of spliced XBP1 (XBP1s) is a major component of its biological effects, but the targets of XBP1s in estrogen receptor (ER)-positive breast cancer are not well understood. Here, we show that the expression of miR-378 and PPARGC1B (host gene of miR-378) is downregulated during UPR. Using chemical and genetic methods, we show that XBP1s is necessary and sufficient for the downregulation of miR-378 and PPARGC1B. Our results show that overexpression of miR-378 significantly suppressed cell growth, colony formation, and migration of ER-positive breast cancer cells. Further, we found that expression of miR-378 sensitised the cells to UPR-induced cell death and anti-estrogens. The expression of miR-378 and PPARGC1B was downregulated in breast cancer, and higher expression of miR-378 is associated with better outcomes in ER-positive breast cancer. We found that miR-378 upregulates the expression of several genes that regulate type I interferon signalling. Analysis of separate cohorts of breast cancer patients showed that a gene signature derived from miR-378 upregulated genes showed a strong association with improved overall and recurrence-free survival in breast cancer. Our results suggest a growth-suppressive role for miR-378 in ER-positive breast cancer where downregulation of miR-378 by XBP1 contributes to endocrine resistance in ER-positive breast cancer.
Collapse
Affiliation(s)
- Vahid Arabkari
- Discipline of Pathology, Cancer Progression and Treatment Research Group, Lambe Institute for Translational Research, School of Medicine, University of Galway, H91TK33 Galway, Ireland; (V.A.); (D.B.); (M.M.H.); (M.W.)
- Krefting Research Centre, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, University of Gothenburg, 40530 Gothenburg, Sweden
| | - David Barua
- Discipline of Pathology, Cancer Progression and Treatment Research Group, Lambe Institute for Translational Research, School of Medicine, University of Galway, H91TK33 Galway, Ireland; (V.A.); (D.B.); (M.M.H.); (M.W.)
| | - Muhammad Mosaraf Hossain
- Discipline of Pathology, Cancer Progression and Treatment Research Group, Lambe Institute for Translational Research, School of Medicine, University of Galway, H91TK33 Galway, Ireland; (V.A.); (D.B.); (M.M.H.); (M.W.)
- Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong 4331, Bangladesh
| | - Mark Webber
- Discipline of Pathology, Cancer Progression and Treatment Research Group, Lambe Institute for Translational Research, School of Medicine, University of Galway, H91TK33 Galway, Ireland; (V.A.); (D.B.); (M.M.H.); (M.W.)
| | - Terry Smith
- Molecular Diagnostic Research Group, College of Science, University of Galway, H91TK33 Galway, Ireland;
| | - Ananya Gupta
- Discipline of Physiology, School of Medicine, University of Galway, H91TK33 Galway, Ireland;
| | - Sanjeev Gupta
- Discipline of Pathology, Cancer Progression and Treatment Research Group, Lambe Institute for Translational Research, School of Medicine, University of Galway, H91TK33 Galway, Ireland; (V.A.); (D.B.); (M.M.H.); (M.W.)
| |
Collapse
|