Man Kin Wong

All Publications

• SMCHD1 activates the expression of genes required for the expansion of human myoblasts NUCLEIC ACIDS RESEARCH Wong, M., Hachmer, S., Gardner, E., Runfola, V., Arezza, E., Megeney, L. A., Emerson Jr, C. P., Gabellini, D., Dilworth, F. 2024

  Abstract

  SMCHD1 is an epigenetic regulatory protein known to modulate the targeted repression of large chromatin domains. Diminished SMCHD1 function in muscle fibers causes Facioscapulohumeral Muscular Dystrophy (FSHD2) through derepression of the D4Z4 chromatin domain, an event which permits the aberrant expression of the disease-causing gene DUX4. Given that SMCHD1 plays a broader role in establishing the cellular epigenome, we examined whether loss of SMCHD1 function might affect muscle homeostasis through additional mechanisms. Here we show that acute depletion of SMCHD1 results in a DUX4-independent defect in myoblast proliferation. Genomic and transcriptomic experiments determined that SMCHD1 associates with enhancers of genes controlling cell cycle to activate their expression. Amongst these cell cycle regulatory genes, we identified LAP2 as a key target of SMCHD1 required for the expansion of myoblasts, where the ectopic expression of LAP2 rescues the proliferation defect of SMCHD1-depleted cells. Thus, the epigenetic regulator SMCHD1 can play the role of a transcriptional co-activator for maintaining the expression of genes required for muscle progenitor expansion. This DUX4-independent role for SMCHD1 in myoblasts suggests that the pathology of FSHD2 may be a consequence of defective muscle regeneration in addition to the muscle wasting caused by spurious DUX4 expression.

  View details for DOI 10.1093/nar/gkae600

  View details for Web of Science ID 001266366700001

  View details for PubMedID 38994563

• A fast Myosin super enhancer dictates muscle fiber phenotype through competitive interactions with Myosin genes. Nature communications Dos Santos, M., Backer, S., Auradé, F., Wong, M. M., Wurmser, M., Pierre, R., Langa, F., Do Cruzeiro, M., Schmitt, A., Concordet, J. P., Sotiropoulos, A., Jeffrey Dilworth, F., Noordermeer, D., Relaix, F., Sakakibara, I., Maire, P. 2022; 13 (1): 1039

  Abstract

  The contractile properties of adult myofibers are shaped by their Myosin heavy chain isoform content. Here, we identify by snATAC-seq a 42 kb super-enhancer at the locus regrouping the fast Myosin genes. By 4C-seq we show that active fast Myosin promoters interact with this super-enhancer by DNA looping, leading to the activation of a single promoter per nucleus. A rainbow mouse transgenic model of the locus including the super-enhancer recapitulates the endogenous spatio-temporal expression of adult fast Myosin genes. In situ deletion of the super-enhancer by CRISPR/Cas9 editing demonstrates its major role in the control of associated fast Myosin genes, and deletion of two fast Myosin genes at the locus reveals an active competition of the promoters for the shared super-enhancer. Last, by disrupting the organization of fast Myosin, we uncover positional heterogeneity within limb skeletal muscles that may underlie selective muscle susceptibility to damage in certain myopathies.

  View details for DOI 10.1038/s41467-022-28666-1

  View details for PubMedID 35210422

  View details for PubMedCentralID PMC8873246

• Chromatin and transcription factor profiling in rare stem cell populations using CUT&Tag. STAR protocols Li, Y., Nakka, K., Olender, T., Gingras-Gelinas, P., Wong, M. M., Robinson, D. C., Bandukwala, H., Palii, C. G., Neyret, O., Brand, M., Blais, A., Dilworth, F. J. 2021; 2 (3): 100751

  Abstract

  Muscle stem cells (MuSCs) are a rare stem cell population that provides myofibers with a remarkable capacity to regenerate after tissue injury. Here, we have adapted the Cleavage Under Target and Tagmentation technology to the mapping of the chromatin landscape and transcription factor binding in 50,000 activated MuSCs isolated from injured mouse hindlimb muscles. We have applied this same approach to human CD34+ hematopoietic stem and progenitor cells. This protocol could be adapted to any rare stem cell population. For complete details on the use and execution of this protocol, please refer to Robinson et al. (2021).

  View details for DOI 10.1016/j.xpro.2021.100751

  View details for PubMedID 34467227

  View details for PubMedCentralID PMC8384913

• Transcription Factor AP4 Mediates Cell Fate Decisions: To Divide, Age, or Die. Cancers Wong, M. M., Joyson, S. M., Hermeking, H., Chiu, S. K. 2021; 13 (4)

  Abstract

  Activating Enhancer-Binding Protein 4 (AP4)/transcription factor AP4 (TFAP4) is a basic-helix-loop-helix-leucine-zipper transcription factor that was first identified as a protein bound to SV40 promoters more than 30 years ago. Almost 15 years later, AP4 was characterized as a target of the c-Myc transcription factor, which is the product of a prototypic oncogene that is activated in the majority of tumors. Interestingly, AP4 seems to represent a central hub downstream of c-Myc and N-Myc that mediates some of their functions, such as proliferation and epithelial-mesenchymal transition (EMT). Elevated AP4 expression is associated with progression of cancer and poor patient prognosis in multiple tumor types. Deletion of AP4 in mice points to roles of AP4 in the control of stemness, tumor initiation and adaptive immunity. Interestingly, ex vivo AP4 inactivation results in increased DNA damage, senescence, and apoptosis, which may be caused by defective cell cycle progression. Here, we will summarize the roles of AP4 as a transcriptional repressor and activator of target genes and the contribution of protein and non-coding RNAs encoded by these genes, in regulating the above mentioned processes. In addition, proteins interacting with or regulating AP4 and the cellular signaling pathways altered after AP4 dysregulation in tumor cells will be discussed.

  View details for DOI 10.3390/cancers13040676

  View details for PubMedID 33567514

  View details for PubMedCentralID PMC7914591

• Intron Retained, Transcript Detained: Intron Retention as a Hallmark of the Quiescent Satellite Cell State. Developmental cell Nakka, K., Kovac, R., Wong, M. M., Dilworth, F. J. 2020; 53 (6): 623-625

  Abstract

  Molecular signatures defining quiescence in muscle satellite cells (mSCs) remain enigmatic. In this issue of Developmental Cell, Yue et al. adapted an in vivo fixation approach to isolate dormant mSCs from healthy muscle. Characterizing the transcriptome from these cells, they identified intron retention as a novel hallmark of mSC quiescence.

  View details for DOI 10.1016/j.devcel.2020.05.028

  View details for PubMedID 32574590

• Ectopic AP4 expression induces cellular senescence via activation of p53 in long-term confluent retinal pigment epithelial cells. Experimental cell research Wang, Y., Wong, M. M., Zhang, X., Chiu, S. K. 2015; 339 (1): 135-46

  Abstract

  When cells are grown to confluence, cell-cell contact inhibition occurs and drives the cells to enter reversible quiescence rather than senescence. Confluent retinal pigment epithelial (RPE) cells exhibiting contact inhibition was used as a model in this study to examine the role of overexpression of transcription factor AP4, a highly expressed transcription factor in many types of cancer, in these cells during long-term culture. We generated stable inducible RPE cell clones expressing AP4 or AP4 without the DNA binding domain (DN-AP4) and observed that, when cultured for 24 days, RPE cells with a high level of AP4 exhibit a large, flattened morphology and even cease proliferating; these changes were not observed in DN-AP4-expressing cells or non-induced cells. In addition, AP4-expressing cells exhibited senescence-associated β-galactosidase activity and the senescence-associated secretory phenotype. We demonstrated that the induced cellular senescence was mediated by enhanced p53 expression and that AP4 regulates the p53 gene by binding directly to two of the three E-boxes present on the promoter of the p53 gene. Moreover, we showed that serum is essential for AP4 in inducing p53-associated cellular senescence. Collectively, we showed that overexpression of AP4 mediates cellular senescence involving in activation of p53 in long-term post-confluent RPE cells.

  View details for DOI 10.1016/j.yexcr.2015.09.013

  View details for PubMedID 26439195

• Cropped, Drosophila transcription factor AP-4, controls tracheal terminal branching and cell growth BMC DEVELOPMENTAL BIOLOGY Wong, M., Liu, M., Chiu, S. 2015; 15: 20

  Abstract

  Endothelial or epithelial cellular branching is vital in development and cancer progression; however, the molecular mechanisms of these processes are not clear. In Drosophila, terminal cell at the end of some tracheal tube ramifies numerous fine branches on the internal organs to supply oxygen. To discover more genes involved in terminal branching, we searched for mutants with very few terminal branches using the Kiss enhancer-trap line collection.In this analysis, we identified cropped (crp), encoding the Drosophila homolog of the transcription activator protein AP-4. Overexpressing the wild-type crp gene or a mutant that lacks the DNA-binding region in either the tracheal tissues or terminal cells led to a loss-of-function phenotype, implying that crp can affect terminal branching. Unexpectedly, the ectopic expression of cropped also led to enlarged organs, and cell-counting experiments on the salivary glands suggest that elevated levels of AP-4 increase cell size and organ size. Like its mammalian counterpart, cropped is controlled by dMyc, as ectopic expression of dMyc in terminal cells increased cellular branching and the Cropped protein levels in vivo.We find that the branching morphogenesis of terminal cells of the tracheal tubes in Drosophila requires the dMyc-dependent activation of Cropped/AP-4 protein to increase the cell growth of terminal cells.

  View details for DOI 10.1186/s12861-015-0069-6

  View details for Web of Science ID 000354347500001

  View details for PubMedID 25888431

  View details for PubMedCentralID PMC4430030

• Luminescent ruthenium(II) complex bearing bipyridine and N-heterocyclic carbene-based C∧N∧C pincer ligand for live-cell imaging of endocytosis. Scientific reports Tsui, W. K., Chung, L. H., Wong, M. M., Tsang, W. H., Lo, H. S., Liu, Y., Leung, C. H., Ma, D. L., Chiu, S. K., Wong, C. Y. 2015; 5: 9070

  Abstract

  Luminescent ruthenium(II)-cyanide complex with N-heterocyclic carbene pincer ligand C(∧)N(∧)C = 2,6-bis(1-butylimidazol-2-ylidene)pyridine and 2,2'-bipyridine (bpy) shows minimal cytotoxicity to both human breast carcinoma cell (MCF-7) and human retinal pigmented epithelium cell (RPE) in a wide range of concentration (0.1-500 μM), and can be used for the luminescent imaging of endocytosis of the complex in these cells.

  View details for DOI 10.1038/srep09070

  View details for PubMedID 25765974

  View details for PubMedCentralID PMC4357851

• Effects of nanoparticle size and cell type on high sensitivity cell detection using a localized surface plasmon resonance biosensor. Biosensors & bioelectronics Liu, F., Wong, M. M., Chiu, S. K., Lin, H., Ho, J. C., Pang, S. W. 2014; 55: 141-8

  Abstract

  A localized surface plasmon resonance (LSPR) effect was used to distinguish cell concentration on ordered arrays of Au nanoparticles (NPs) on glass substrates. Human-derived retinal pigment epithelial RPE-1 cells with flatter bodies and higher confluency were compared with breast cancer MCF-7 cells. Nanosphere lithography was used to form Au NPs with average diameters of 500 and 60 nm in order to compare cell detection range, resonance peak shift, and cell concentration sensitivity. A larger cell concentration range was detected on the larger 500 nm Au NPs compared to 60 nm Au NPs (8.56 × 10(3)-1.09 × 10(6) vs. 3.43 × 10(4)-2.73 × 10(5)cells/ml). Resonance peak shift could distinguish RPE-1 from MCF-7 cells on both Au NPs. RPE-1 cells consistently displayed larger resonance peak shifts compared to MCF-7 cells until the detection became saturated at higher concentration. For both types of cells, higher concentration sensitivity in the range of ~10(4)-10(6)cells/ml was observed on 500 nm compared to 60 nm Au NPs. Our results show that cells on Au NPs can be detected in a large range and at low concentration. Optimal cell sensing can be achieved by altering the dimensions of Au NPs according to different cell characteristics and concentrations.

  View details for DOI 10.1016/j.bios.2013.11.075

  View details for PubMedID 24373953

• Taxifolin enhances andrographolide-induced mitotic arrest and apoptosis in human prostate cancer cells via spindle assembly checkpoint activation. PloS one Zhang, Z. R., Al Zaharna, M., Wong, M. M., Chiu, S. K., Cheung, H. Y. 2013; 8 (1): e54577

  Abstract

  Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

  View details for DOI 10.1371/journal.pone.0054577

  View details for PubMedID 23382917

  View details for PubMedCentralID PMC3557238

• Differential actions of chlorhexidine on the cell wall of Bacillus subtilis and Escherichia coli. PloS one Cheung, H. Y., Wong, M. M., Cheung, S. H., Liang, L. Y., Lam, Y. W., Chiu, S. K. 2012; 7 (5): e36659

  Abstract

  Chlorhexidine is a chlorinated phenolic disinfectant used commonly in mouthwash for its action against bacteria. However, a comparative study of the action of chlorhexidine on the cell morphology of gram-positive and gram-negative bacteria is lacking. In this study, the actions of chlorhexidine on the cell morphology were identified with the aids of electron microscopy. After exposure to chlorhexidine, numerous spots of indentation on the cell wall were found in both Bacillus subtilis and Escherichia coli. The number of indentation spots increased with time of incubation and increasing chlorhexidine concentration. Interestingly, the dented spots found in B. subtilis appeared mainly at the hemispherical caps of the cells, while in E. coli the dented spots were found all over the cells. After being exposed to chlorhexidine for a prolonged period, leakage of cellular contents and subsequent ghost cells were observed, especially from B subtilis. By using 2-D gel/MS-MS analysis, five proteins related to purine nucleoside interconversion and metabolism were preferentially induced in the cell wall of E. coli, while three proteins related to stress response and four others in amino acid biosynthesis were up-regulated in the cell wall materials of B. subtilis. The localized morphological damages together with the biochemical and protein analysis of the chlorhexidine-treated cells suggest that chlorhexidine may act on the differentially distributed lipids in the cell membranes/wall of B. subtilis and E. coli.

  View details for DOI 10.1371/journal.pone.0036659

  View details for PubMedID 22606280

  View details for PubMedCentralID PMC3350502

• Cadmium Sulfide Silver Nanoplate Hybrid Structure: Synthesis and Fluorescence Enhancement JOURNAL OF PHYSICAL CHEMISTRY C Lin, S., Wong, M., Pat, P., Wong, C., Chiu, S., Pun, E. 2011; 115 (44): 21604-21609

  View details for DOI 10.1021/jp2059326

  View details for Web of Science ID 000296394300010