寡突膠質細胞(Oligodendrocyte)為產生髓鞘的細胞，是中樞神經系統(CNS)中不可或缺的存在，而髓鞘對於支持軸突結構和加速電訊號傳導尤為重要。氧氣對於寡突膠質細胞分化和白質發育至關重要，而缺少氧氣會引發寡突膠質細胞死亡並導致相關的疾病。Casein Kinase 2 (CK2)是一種絲胺酸/蘇胺酸激酶可以調節多種細胞路徑，包括細胞增殖、分化和對缺氧狀況的反應。實驗室之前研究結果表明，過度表現CK2的α次單元可以促進寡突膠質細胞分化並加速腦白質修復和髓鞘再生，但是CK2α在腦缺氧過程中對寡突膠質細胞之影響有待釐清。本研究發現缺氧環境會導致寡突膠質細胞中CK2α的表達減少，且寡突膠質細胞中CK2α過度表達會導致寡突膠質細胞在缺氧條件下死亡。為了探討CK2α從促進分化到誘導細胞死亡的作用機轉，我們利用免疫沉降法搭配質譜分析發現了寡突膠質細胞中一個潛在的CK2α磷酸化目標，即Bcl2相關轉錄因子Bclaf1，在缺氧時會促進寡突膠質細胞凋亡。實驗處理臨床級CK2抑制劑 Silmitasertib (cx-4945)降低Bclaf1磷酸化和已知可抑制Bclaf1表現量的薑黃素(curcumin)，可以減少表現Caspase-3剪切蛋白的凋亡細胞，從而提高缺氧條件下寡突膠質細胞的數量，以利後續白質修復與髓鞘再生。總而言之，阻斷CK2-Bclaf1路徑有利於保護白質免受缺氧損傷。

Oligodendrocytes (OLs) are indispensable in the central nervous system (CNS) as the main producers of myelin sheaths, which are crucial for supporting axonal structure and speeding up electrical signal conduction. Oxygen accessibility is critical for OL differentiation and white matter development, while hypoxia triggers OL cell death and contributes to interconnected diseases. Casein kinase 2 (CK2), a serine/threonine kinase, regulates multiple cellular processes, including cell proliferation, differentiation, apoptosis, and the response to hypoxia. Recent findings in our lab show that CK2α promotes OL differentiation and accelerates white matter repair and remyelination after injury. However, the specific mechanisms by which CK2α influences OLs under hypoxic conditions remain unclear and warrant further investigation. This study reveals that hypoxia induces a reduction in CK2α expression in OLs, while overexpression of CK2α under hypoxic conditions leads to OL apoptosis marked by cleaved caspase-3. To investigate the transition of CK2α from promoting differentiation to inducing cell death, we assumed immunoprecipitation (IP) coupled with mass spectrometry (MSp), identifying the Bcl2-associated transcription factor (Bclaf1) as a potential CK2α phosphorylation target in OLs. Under hypoxic conditions, Bclaf1 levels and its phosphorylation positively contribute to OL apoptosis. Treatment with Silmitasertib (CX-4945), a clinical-grade CK2 inhibitor, and an herbal supplement, curcumin, which is known to suppress Bclaf1 expression, valuably reduces Bclaf1 level and phosphorylation, and decreases the number of apoptotic OLs in vitro and in vivo. These treatments collectively increase the survival of OLs under hypoxic conditions, thereby promoting subsequent white matter repair and myelination. Collectively, blocking the CK2-Bclaf1 signaling pathway could be advantageous for protecting white matter from hypoxic injury.

1. J. Stiles, T. L. Jernigan, The basics of brain development. Neuropsychol Rev 20, 327-348 (2010).
2. C. Lebel, S. Deoni, The development of brain white matter microstructure. Neuroimage 182, 207-218 (2018).
3. J. Dubois et al., The early development of brain white matter: a review of imaging studies in fetuses, newborns and infants. Neuroscience 276, 48-71 (2014).
4. C. D. Cristobal, H. K. Lee, Development of myelinating glia: An overview. Glia 70, 2237-2259 (2022).
5. A. S. Saab, I. D. Tzvetanova, K. A. Nave, The role of myelin and oligodendrocytes in axonal energy metabolism. Curr Opin Neurobiol 23, 1065-1072 (2013).
6. B. M. Morrison, Y. Lee, J. D. Rothstein, Oligodendroglia: metabolic supporters of axons. Trends Cell Biol 23, 644-651 (2013).
7. R. D. McKinnon, T. Matsui, M. Dubois-Dalcq, S. A. Aaronson, FGF modulates the PDGF-driven pathway of oligodendrocyte development. Neuron 5, 603-614 (1990).
8. P. Li et al., Expression of NG2 and platelet-derived growth factor receptor alpha in the developing neonatal rat brain. Neural Regen Res 12, 1843-1852 (2017).
9. M. K. Fard et al., BCAS1 expression defines a population of early myelinating oligodendrocytes in multiple sclerosis lesions. Sci Transl Med 9 (2017).
10. M. Buntinx et al., Characterization of three human oligodendroglial cell lines as a model to study oligodendrocyte injury: morphology and oligodendrocyte-specific gene expression. J Neurocytol 32, 25-38 (2003).
11. C. W. Campagnoni, G. D. Carey, A. T. Campagnoni, Synthesis of myelin basic proteins in the developing mouse brain. Arch Biochem Biophys 190, 118-125 (1978).
12. Q. R. Lu et al., Common developmental requirement for Olig function indicates a motor neuron/oligodendrocyte connection. Cell 109, 75-86 (2002).
13. E. Sock, M. Wegner, Using the lineage determinants Olig2 and Sox10 to explore transcriptional regulation of oligodendrocyte development. Dev Neurobiol 81, 892-901 (2021).
14. M. B. Rone et al., Oligodendrogliopathy in Multiple Sclerosis: Low Glycolytic Metabolic Rate Promotes Oligodendrocyte Survival. J Neurosci 36, 4698-4707 (2016).
15. B. M. Affeldt, A. Obenaus, J. Chan, A. C. Pardo, Region specific oligodendrocyte transcription factor expression in a model of neonatal hypoxic injury. Int J Dev Neurosci 61, 1-11 (2017).
16. M. Ziemka-Nalecz et al., Impact of neonatal hypoxia-ischaemia on oligodendrocyte survival, maturation and myelinating potential. J Cell Mol Med 22, 207-222 (2018).
17. K. L. P. Long et al., Regional gray matter oligodendrocyte- and myelin-related measures are associated with differential susceptibility to stress-induced behavior in rats and humans. Transl Psychiatry 11, 631 (2021).
18. V. A. Russell et al., Response variability in Attention-Deficit/Hyperactivity Disorder: a neuronal and glial energetics hypothesis. Behav Brain Funct 2, 30 (2006).
19. R. D. Fields, Myelination: an overlooked mechanism of synaptic plasticity? Neuroscientist 11, 528-531 (2005).
20. F. Wang et al., Enhancing Oligodendrocyte Myelination Rescues Synaptic Loss and Improves Functional Recovery after Chronic Hypoxia. Neuron 99, 689-701 e685 (2018).
21. H. Nguyen, W. Zhu, S. Baltan, Casein Kinase 2 Signaling in White Matter Stroke. Front Mol Biosci 9, 908521 (2022).
22. C. Y. Wang et al., Daam2 phosphorylation by CK2alpha negatively regulates Wnt activity during white matter development and injury. Proc Natl Acad Sci U S A 120, e2304112120 (2023).
23. C. Borgo, C. D'Amore, S. Sarno, M. Salvi, M. Ruzzene, Protein kinase CK2: a potential therapeutic target for diverse human diseases. Signal Transduct Target Ther 6, 183 (2021).
24. D. Mottet, S. P. Ruys, C. Demazy, M. Raes, C. Michiels, Role for casein kinase 2 in the regulation of HIF-1 activity. Int J Cancer 117, 764-774 (2005).
25. S. Q. Liu et al., Matrine promotes oligodendrocyte development in CNS autoimmunity through the PI3K/Akt signaling pathway. Life Sci 180, 36-41 (2017).
26. A. Bernardo, C. Plumitallo, C. De Nuccio, S. Visentin, L. Minghetti, Curcumin promotes oligodendrocyte differentiation and their protection against TNF-alpha through the activation of the nuclear receptor PPAR-gamma. Sci Rep 11, 4952 (2021).
27. S. Stone et al., NF-kappaB Activation Protects Oligodendrocytes against Inflammation. J Neurosci 37, 9332-9344 (2017).
28. Z. Yu, J. Zhu, H. Wang, H. Li, X. Jin, Function of BCLAF1 in human disease. Oncol Lett 23, 58 (2022).
29. L. Lamy et al., Control of autophagic cell death by caspase-10 in multiple myeloma. Cancer Cell 23, 435-449 (2013).
30. R. Zhang et al., Bclaf1 regulates c-FLIP expression and protects cells from TNF-induced apoptosis and tissue injury. European Molecular Biology Organization Rep 23, e52702 (2022).
31. K. I. Savage et al., Identification of a BRCA1-mRNA splicing complex required for efficient DNA repair and maintenance of genomic stability. Mol Cell 54, 445-459 (2014).
32. A. W. Shao et al., Bclaf1 is an important NF-kappaB signaling transducer and C/EBPbeta regulator in DNA damage-induced senescence. Cell Death Differ 23, 865-875 (2016).
33. M. Lowe et al., Cry2 Is Critical for Circadian Regulation of Myogenic Differentiation by Bclaf1-Mediated mRNA Stabilization of Cyclin D1 and Tmem176b. Cell Rep 22, 2118-2132 (2018).
34. Y. Wen et al., Bclaf1 promotes angiogenesis by regulating HIF-1alpha transcription in hepatocellular carcinoma. Oncogene 38, 1845-1859 (2019).
35. M. Tsuji, M. A. Wilson, M. S. Lange, M. V. Johnston, Minocycline worsens hypoxic-ischemic brain injury in a neonatal mouse model. Exp Neurol 189, 58-65 (2004).
36. C. Bai et al., Curcumin induces mitochondrial apoptosis in human hepatoma cells through BCLAF1-mediated modulation of PI3K/AKT/GSK-3beta signaling. Life Sci 306, 120804 (2022).
37. J. Zhu, J. Qu, Y. Fan, R. Zhang, X. Wang, Curcumin Inhibits Invasion and Epithelial-Mesenchymal Transition in Hepatocellular Carcinoma Cells by Regulating TET1/Wnt/beta-catenin Signal Axis. Bull Exp Biol Med 173, 770-774 (2022).
38. T. Itoh, A. Itoh, D. Pleasure, Bcl-2-related protein family gene expression during oligodendroglial differentiation. J Neurochem 85, 1500-1512 (2003).
39. L. C. Fogarty et al., Mcl-1 and Bcl-xL are essential for survival of the developing nervous system. Cell Death Differ 26, 1501-1515 (2019).
40. Y. Liu, X. Zhang, Expression of cellular oncogene Bcl-xL prevents coronavirus-induced cell death and converts acute infection to persistent infection in progenitor rat oligodendrocytes. J Virol 79, 47-56 (2005).
41. U. F. FitzGerald, T. Gilbey, S. Brodie, S. C. Barnett, Transcription factor expression and cellular redox in immature oligodendrocyte cell death: effect of Bcl-2. Mol Cell Neurosci 22, 516-529 (2003).
42. S. A. Back, X. Gan, Y. Li, P. A. Rosenberg, J. J. Volpe, Maturation-dependent vulnerability of oligodendrocytes to oxidative stress-induced death caused by glutathione depletion. J Neurosci 18, 6241-6253 (1998).
43. E. Pinteaux, M. Perraut, G. Tholey, Distribution of mitochondrial manganese superoxide dismutase among rat glial cells in culture. Glia 22, 408-414 (1998).
44. A. Bernardo, A. Greco, G. Levi, L. Minghetti, Differential lipid peroxidation, Mn superoxide, and bcl-2 expression contribute to the maturation-dependent vulnerability of oligodendrocytes to oxidative stress. J Neuropathol Exp Neurol 62, 509-519 (2003).
45. J. E. Merrill, L. J. Ignarro, M. P. Sherman, J. Melinek, T. E. Lane, Microglial cell cytotoxicity of oligodendrocytes is mediated through nitric oxide. J Immunol 151, 2132-2141 (1993).
46. B. Gao et al., The Histone Acetyltransferase Gcn5 Positively Regulates T Cell Activation. J Immunol 198, 3927-3938 (2017).
47. J. P. McPherson et al., Essential role for Bclaf1 in lung development and immune system function. Cell Death Differ 16, 331-339 (2009).
48. L. Fang et al., Enhanced breast cancer progression by mutant p53 is inhibited by the circular RNA circ-Ccnb1. Cell Death Differ 25, 2195-2208 (2018).
49. X. Liu, L. Wu, L. Wang, Y. Li, Identification and classification of glioma subtypes based on RNA-binding proteins. Comput Biol Med 174, 108404 (2024).
50. H. Wu et al., Targeting the BCKDK/BCLAF1/MYC/HK2 axis to alter aerobic glycolysis and overcome Trametinib resistance in lung cancer. Cell Death Differ 10.1038/s41418-025-01531-6 (2025).
51. Y. Y. Lee, Y. B. Yu, H. P. Gunawardena, L. Xie, X. Chen, BCLAF1 is a radiation-induced H2AX-interacting partner involved in gammaH2AX-mediated regulation of apoptosis and DNA repair. Cell Death Dis 3, e359 (2012).
52. C. Qin et al., Bclaf1 critically regulates the type I interferon response and is degraded by alphaherpesvirus US3. PLoS Pathog 15, e1007559 (2019).
53. Z. Ai, Revealing key regulators of neutrophil function during inflammation by re-analysing single-cell RNA-seq. PLoS One 17, e0276460 (2022).
54. S. Baltan et al., CK2 inhibition protects white matter from ischemic injury. Neurosci Lett 687, 37-42 (2018).
55. C. Bastian et al., CK2 inhibition confers functional protection to young and aging axons against ischemia by differentially regulating the CDK5 and AKT signaling pathways. Neurobiol Dis 126, 47-61 (2019).
56. J. Bliesath et al., Combined inhibition of EGFR and CK2 augments the attenuation of PI3K-Akt-mTOR signaling and the killing of cancer cells. Cancer Lett 322, 113-118 (2012).
57. A. Siddiqui-Jain et al., CX-4945, an orally bioavailable selective inhibitor of protein kinase CK2, inhibits prosurvival and angiogenic signaling and exhibits antitumor efficacy. Cancer Res 70, 10288-10298 (2010).
58. B. Guerra et al., Protein kinase CK2 inhibition is associated with the destabilization of HIF-1alpha in human cancer cells. Cancer Lett 356, 751-761 (2015).
59. H. A. Park, K. Broman, E. A. Jonas, Oxidative stress battles neuronal Bcl-xL in a fight to the death. Neural Regen Res 16, 12-15 (2021).
60. G. Cozza et al., Biochemical and cellular mechanism of protein kinase CK2 inhibition by deceptive curcumin. Federation of European Biochemical Societies J 287, 1850-1864 (2020).
61. W. Yu et al., Curcumin Protects Neonatal Rat Cardiomyocytes against High Glucose-Induced Apoptosis via PI3K/Akt Signalling Pathway. J Diabetes Res 2016, 4158591 (2016).
62. J. Ahn, H. Lee, S. Kim, T. Ha, Curcumin-induced suppression of adipogenic differentiation is accompanied by activation of Wnt/beta-catenin signaling. Am J Physiol Cell Physiol 298, C1510-1516 (2010).