HN1 Functions in Protein Synthesis Regulation via mTOR-RPS6 Axis and Maintains Nucleolar Integrity

Abstract

Haematological and Neurological Expressed 1 (HN1) is an oncogene for various cancers and previously has been linked with centrosome clustering and cell cycle pathways. Moreover, HN1 has recently been reported to activate mTOR signalling, which is the regulator of ribosome biogenesis and maintenance. We explored the role of HN1 in mTOR signalling through various gain- and loss-of-function experiments using biochemical approaches in different cell lines. We demonstrated for the first time that HN1 is required for nucleolar organiser region (NOR) integrity and function. Immunoprecipitation-based association and colocalization studies demonstrated that HN1 is an important component of the mTOR-RPS6 axis, and its depletion results with reduced mRNA translation in mammalian cancer cell lines. This study also demonstrated that the depletion of HN1 leads to the irregular distribution of nucleolar structures, potentially leading to cell cycle deregulation as reported previously. Accordingly, components of the translation machinery aggregate with a distinct speckled pattern, lose their essential interactions and ultimately impair mRNA translation efficiency when the HN1 is depleted. These results suggest that HN1 is an essential component of the nucleolus, required for ribosome biogenesis as well as global mRNA translation.

Keywords

HN1 / mTOR / nucleolin / nucleolus integrity / ribosome biogenesis / RPS6

References

[1] H. Li, S. Fan, Z. Gong, J. Y. K. Chan, M. C. F. Tong, and G. G. Chen, “Role of Hematological and Neurological Expressed 1 (HN1) in Human Cancers,” Critical Reviews in Oncology/Hematology 201 (2024): 104446, https://doi.org/10.1016/j.critrevonc.2024.104446.

[2] W. Tang, Y.-H. Lai, X.-D. Han, P. M. C. Wong, L. L. Peters, and D. H. K. Chui, “Murine Hn1 on Chromosome 11 Is Expressed in Hemopoietic and Brain Tissues,” Mammalian Genome 8, no. 9 (1997): 695-696, https://doi.org/10.1007/s003359900540.

[3] J. Chen, J. Qiu, F. Li, et al., “HN1 Promotes Tumor Associated Lymphangiogenesis and Lymph Node Metastasis via NF-κB Signaling Activation in Cervical Carcinoma,” Biochemical and Biophysical Research Communications 530, no. 1 (2020): 87-94, https://doi.org/10.1016/j.bbrc.2020.05.062.

[4] Z. Liu, D. Yang, Y. Li, Y. Jiao, and G. Lv, “HN1 as a Diagnostic and Prognostic Biomarker for Liver Cancer,” Bioscience Reports 40, no. 7 (2020): BSR20200316, https://doi.org/10.1042/BSR20200316.

[5] Z. Pan, Q. Fang, L. Li, et al., “HN1 Promotes Tumor Growth and Metastasis of Anaplastic Thyroid Carcinoma by Interacting With STMN1,” Cancer Letters 501 (2021): 31-42, https://doi.org/10.1016/j.canlet.2020.12.026.

[6] N. Karpova, Y. Bobinnec, S. Fouix, P. Huitorel, and A. Debec, “Jupiter, a New Drosophila Protein Associated With Microtubules,” Cell Motility and the Cytoskeleton 63, no. 5 (2006): 301-312, https://doi.org/10.1002/cm.20124.

[7] G. Zhou, J. Wang, Y. Zhang, et al., “Cloning, Expression and Subcellular Localization of HN1 and HN1L Genes, as Well as Characterization of Their Orthologs, Defining an Evolutionarily Conserved Gene Family,” Gene 331 (2004): 115-123, https://doi.org/10.1016/j.gene.2004.02.025.

[8] A. Javed, G. Özduman, L. Varışlı, B. E. Öztürk, and K. S. Korkmaz, “HN1 Is Enriched in the S-Phase, Phosphorylated in Mitosis, and Contributes to Cyclin B1 Degradation in Prostate Cancer Cells,” Biology 12, no. 2 (2023): 189, https://doi.org/10.3390/biology12020189.

[9] L. Varisli, A. Javed, B. E. Ozturk, et al., “HN1 Interacts With γ-Tubulin to Regulate Centrosomes in Advanced Prostate Cancer Cells,” Cell Cycle 20, no. 17 (2021): 1723-1744, https://doi.org/10.1080/15384101.2021.1962624.

[10] J. Feng, Y. Liu, T. Fang, J. Zhu, G. Wang, and J. Li, “Hematological and Neurological Expressed 1 (HN1) Activates c-Myc Signaling by Inhibiting Ubiquitin-Mediated Proteasomal Degradation of c-Myc in Hepatocellular Carcinoma,” Cell Biology International 47, no. 3 (2023): 560-572, https://doi.org/10.1002/cbin.11957.

[11] R. Wang, Y. Fu, M. Yao, et al., “The HN1/HMGB1 Axis Promotes the Proliferation and Metastasis of Hepatocellular Carcinoma and Attenuates the Chemosensitivity to Oxaliplatin,” FEBS Journal 289, no. 20 (2022): 6400-6419, https://doi.org/10.1111/febs.16531.

[12] C. Enenkel, R. W. Kang, F. Wilfling, and O. P. Ernst, “Intracellular Localization of the Proteasome in Response to Stress Conditions,” Journal of Biological Chemistry 298, no. 7 (2022): 102083, https://doi.org/10.1016/j.jbc.2022.102083.

[13] H. Mahboubi and U. Stochaj, “Cytoplasmic Stress Granules: Dynamic Modulators of Cell Signaling and Disease,” Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease 1863, no. 4 (2017): 884-895, https://doi.org/10.1016/j.bbadis.2016.12.022.

[14] D. A. Altomare and A. R. Khaled, “Homeostasis and the Importance for a Balance Between AKT/mTOR Activity and Intracellular Signaling,” Current Medicinal Chemistry 19, no. 22 (2012): 3748-3762, https://doi.org/10.2174/092986712801661130.

[15] P. Li, L.-H. Qian, Y.-N. Liao, et al., “Hematological and Neurological Expressed 1 Promotes Tumor Progression Through mTOR Signaling in Ovarian Cancer,” Reproductive Sciences 31, no. 7 (2024): 1868-1880, https://doi.org/10.1007/s43032-024-01456-4.

[16] A. A. Alasar, Ö. Tüncel, A. B. Gelmez, B. Sağlam, İ. E. Vatansever, and B. Akgül, “Genomewide m6A Mapping Uncovers Dynamic Changes in the m6A Epitranscriptome of Cisplatin-Treated Apoptotic HeLa Cells,” Cells 11, no. 23 (2022): 3905, https://doi.org/10.3390/cells11233905.

[17] L. Varisli, C. Gonen-Korkmaz, B. Debelec-Butuner, et al., “Ubiquitously Expressed Hematological and Neurological Expressed 1 Downregulates Akt-Mediated GSK3β Signaling, and Its Knockdown Results in Deregulated G2/M Transition in Prostate Cells,” DNA and Cell Biology 30, no. 6 (2011): 419-429, https://doi.org/10.1089/dna.2010.1128.

[18] S. Ramon y Cajal, J. Castellvi, S. Hümmer, V. Peg, J. Pelletier, and N. Sonenberg, “Beyond Molecular Tumor Heterogeneity: Protein Synthesis Takes Control,” Oncogene 37, no. 19 (2018): 2490-2501, https://doi.org/10.1038/s41388-018-0152-0.

[19] M. Goelzer, J. Goelzer, M. L. Ferguson, C. P. Neu, and G. Uzer, “Nuclear Envelope Mechanobiology: Linking the Nuclear Structure and Function,” Nucleus 12, no. 1 (2021): 90-114, https://doi.org/10.1080/19491034.2021.1962610.

[20] A. Németh and G. Längst, “Genome Organization in and Around the Nucleolus,” Trends in Genetics 27, no. 4 (2011): 149-156, https://doi.org/10.1016/j.tig.2011.01.002.

[21] F.-M. Boisvert, S. van Koningsbruggen, J. Navascués, and A. I. Lamond, “The Multifunctional Nucleolus,” Nature Reviews Molecular Cell Biology 8, no. 7 (2007): 574-585, https://doi.org/10.1038/nrm2184.

[22] A. V. Cerqueira and B. Lemos, “Ribosomal DNA and the Nucleolus as Keystones of Nuclear Architecture, Organization, and Function,” Trends in Genetics 35, no. 10 (2019): 710-723, https://doi.org/10.1016/j.tig.2019.07.011.

[23] U. Stochaj and S. C. Weber, “Nucleolar Organization and Functions in Health and Disease,” Cells 9, no. 3 (2020): 526, https://doi.org/10.3390/cells9030526.

[24] V. Tiku and A. Antebi, “Nucleolar Function in Lifespan Regulation,” Trends in Cell Biology 28, no. 8 (2018): 662-672, https://doi.org/10.1016/j.tcb.2018.03.007.

[25] A. Corman, O. Sirozh, V. Lafarga, and O. Fernandez-Capetillo, “Targeting the Nucleolus as a Therapeutic Strategy in Human Disease,” Trends in Biochemical Sciences 48, no. 3 (2023): 274-287, https://doi.org/10.1016/j.tibs.2022.09.006.

[26] M. Derenzini, L. Montanaro, and D. Treré, “What the Nucleolus Says to a Tumour Pathologist,” Histopathology 54, no. 6 (2009): 753-762, https://doi.org/10.1111/j.1365-2559.2008.03168.x.

[27] K. A. Elsharawy, M. S. Toss, S. Raafat, et al., “Prognostic Significance of Nucleolar Assessment in Invasive Breast Cancer,” Histopathology 76, no. 5 (2020): 671-684, https://doi.org/10.1111/his.14036.

[28] H. Hirai, “Chromosome Dynamics Regulating Genomic Dispersion and Alteration of Nucleolus Organizer Regions (NORs),” Cells 9, no. 4 (2020): 971, https://doi.org/10.3390/cells9040971.

[29] B. McStay, “Nucleolar Organizer Regions: Genomic ‘Dark Matter’ Requiring Illumination,” Genes and Development 30, no. 14 (2016): 1598-1610, https://doi.org/10.1101/gad.283838.116.

[30] M. Tsekrekou, K. Stratigi, and G. Chatzinikolaou, “The Nucleolus: In Genome Maintenance and Repair,” International Journal of Molecular Sciences 18, no. 7 (2017): 1411, https://doi.org/10.3390/ijms18071411.

[31] A. Gentilella, S. C. Kozma, and G. Thomas, “A Liaison Between mTOR Signaling, Ribosome Biogenesis and Cancer,” Biochimica et Biophysica Acta (BBA)-Gene Regulatory Mechanisms 1849, no. 7 (2015): 812-820, https://doi.org/10.1016/j.bbagrm.2015.02.005.

[32] T. Goto, F. Tokunaga, and O. Hisatomi, “Hematological- and Neurological-Expressed Sequence 1 Gene Products in Progenitor Cells During Newt Retinal Development,” Stem Cells International 2012 (2012): 1-6, https://doi.org/10.1155/2012/436042.

[33] T. Özar, A. Javed, G. Özduman, and K. S. Korkmaz, “HN1 Is a Novel Dedifferentiation Factor Involved in Regulating the Cell Cycle and Microtubules in SH-SY5Y Neuroblastoma Cells,” Journal of Cellular Biochemistry (2024): 1-14, https://doi.org/10.1002/jcb.30569.

[34] L. Jiao, Y. Liu, X.-Y. Yu, et al., “Ribosome Biogenesis in Disease: New Players and Therapeutic Targets,” Signal Transduction and Targeted Therapy 8, no. 1 (2023): 15, https://doi.org/10.1038/s41392-022-01285-4.

[35] G. Özduman, F. Şimşek, A. Javed, and K. S. Korkmaz, “HN1 Expression Contributes to Mitotic Fidelity Through Aurora A-PLK1-Eg5 Axis,” Cytoskeleton (2024): 1-11, https://doi.org/10.1002/cm.21928.

RIGHTS & PERMISSIONS

2025 The Author(s). Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.