Medical Biology - Research Publications

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    Trabid patient mutations impede the axonal trafficking of adenomatous polyposis coli to disrupt neurite growth
    Frank, D ; Bergamasco, M ; Mlodzianoski, MJ ; Kueh, A ; Tsui, E ; Hall, C ; Kastrappis, G ; Voss, AK ; McLean, C ; Faux, M ; Rogers, KL ; Tran, B ; Vincan, E ; Komander, D ; Dewson, G ; Tran, H (eLIFE SCIENCES PUBL LTD, 2023-12-15)
    ZRANB1 (human Trabid) missense mutations have been identified in children diagnosed with a range of congenital disorders including reduced brain size, but how Trabid regulates neurodevelopment is not understood. We have characterized these patient mutations in cells and mice to identify a key role for Trabid in the regulation of neurite growth. One of the patient mutations flanked the catalytic cysteine of Trabid and its deubiquitylating (DUB) activity was abrogated. The second variant retained DUB activity, but failed to bind STRIPAK, a large multiprotein assembly implicated in cytoskeleton organization and neural development. Zranb1 knock-in mice harboring either of these patient mutations exhibited reduced neuronal and glial cell densities in the brain and a motor deficit consistent with fewer dopaminergic neurons and projections. Mechanistically, both DUB-impaired and STRIPAK-binding-deficient Trabid variants impeded the trafficking of adenomatous polyposis coli (APC) to microtubule plus-ends. Consequently, the formation of neuronal growth cones and the trajectory of neurite outgrowth from mutant midbrain progenitors were severely compromised. We propose that STRIPAK recruits Trabid to deubiquitylate APC, and that in cells with mutant Trabid, APC becomes hyperubiquitylated and mislocalized causing impaired organization of the cytoskeleton that underlie the neuronal and developmental phenotypes.
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    Three-dimensional genome architecture coordinates key regulators of lineage specification in mammary epithelial cells
    Milevskiy, MJG ; Coughlan, HD ; Kane, SR ; Johanson, TM ; Kordafshari, S ; Chan, WF ; Tsai, M ; Surgenor, E ; Wilcox, S ; Allan, RS ; Chen, Y ; Lindeman, GJ ; Smyth, GK ; Visvader, JE (ELSEVIER, 2023-11-08)
    Although lineage-specific genes have been identified in the mammary gland, little is known about the contribution of the 3D genome organization to gene regulation in the epithelium. Here, we describe the chromatin landscape of the three major epithelial subsets through integration of long- and short-range chromatin interactions, accessibility, histone modifications, and gene expression. While basal genes display exquisite lineage specificity via distal enhancers, luminal-specific genes show widespread promoter priming in basal cells. Cell specificity in luminal progenitors is largely mediated through extensive chromatin interactions with super-enhancers in gene-body regions in addition to interactions with polycomb silencer elements. Moreover, lineage-specific transcription factors appear to be controlled through cell-specific chromatin interactivity. Finally, chromatin accessibility rather than interactivity emerged as a defining feature of the activation of quiescent basal stem cells. This work provides a comprehensive resource for understanding the role of higher-order chromatin interactions in cell-fate specification and differentiation in the adult mouse mammary gland.
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    Stuttering associated with a pathogenic variant in the chaperone protein cyclophilin 40
    Morgan, AT ; Scerri, TS ; Vogel, AP ; Reid, CA ; Quach, M ; Jackson, VE ; McKenzie, C ; Burrows, EL ; Bennett, MF ; Turner, SJ ; Reilly, S ; Horton, SE ; Block, S ; Kefalianos, E ; Frigerio-Domingues, C ; Sainz, E ; Rigbye, KA ; Featherby, TJ ; Richards, KL ; Kueh, A ; Herold, MJ ; Corbett, MA ; Gecz, J ; Helbig, I ; Thompson-Lake, DGY ; Liegeois, FJ ; Morell, RJ ; Hung, A ; Drayna, D ; Scheffer, IE ; Wright, DK ; Bahlo, M ; Hildebrand, MS (OXFORD UNIV PRESS, 2023-12-01)
    Stuttering is a common speech disorder that interrupts speech fluency and tends to cluster in families. Typically, stuttering is characterized by speech sounds, words or syllables which may be repeated or prolonged and speech that may be further interrupted by hesitations or 'blocks'. Rare variants in a small number of genes encoding lysosomal pathway proteins have been linked to stuttering. We studied a large four-generation family in which persistent stuttering was inherited in an autosomal dominant manner with disruption of the cortico-basal-ganglia-thalamo-cortical network found on imaging. Exome sequencing of three affected family members revealed the PPID c.808C>T (p.Pro270Ser) variant that segregated with stuttering in the family. We generated a Ppid p.Pro270Ser knock-in mouse model and performed ex vivo imaging to assess for brain changes. Diffusion-weighted MRI in the mouse revealed significant microstructural changes in the left corticospinal tract, as previously implicated in stuttering. Quantitative susceptibility mapping also detected changes in cortico-striatal-thalamo-cortical loop tissue composition, consistent with findings in affected family members. This is the first report to implicate a chaperone protein in the pathogenesis of stuttering. The humanized Ppid murine model recapitulates network findings observed in affected family members.
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    Two regulatory T cell populations in the visceral adipose tissue shape systemic metabolism
    Torres, SV ; Man, K ; Elmzzahi, T ; Malko, D ; Chisanga, D ; Liao, Y ; Prout, M ; Abbott, CA ; Tang, A ; Wu, J ; Becker, M ; Mason, T ; Haynes, V ; Tsui, C ; Shakiba, MH ; Hamada, D ; Britt, K ; Groom, JR ; Mccoll, SR ; Shi, W ; Watt, MJ ; Le Gros, G ; Pal, B ; Beyer, M ; Vasanthakumar, A ; Kallies, A (NATURE PORTFOLIO, 2024-03)
    Visceral adipose tissue (VAT) is an energy store and endocrine organ critical for metabolic homeostasis. Regulatory T (Treg) cells restrain inflammation to preserve VAT homeostasis and glucose tolerance. Here, we show that the VAT harbors two distinct Treg cell populations: prototypical serum stimulation 2-positive (ST2+) Treg cells that are enriched in males and a previously uncharacterized population of C-X-C motif chemokine receptor 3-positive (CXCR3+) Treg cells that are enriched in females. We show that the transcription factors GATA-binding protein 3 and peroxisome proliferator-activated receptor-γ, together with the cytokine interleukin-33, promote the differentiation of ST2+ VAT Treg cells but repress CXCR3+ Treg cells. Conversely, the differentiation of CXCR3+ Treg cells is mediated by the cytokine interferon-γ and the transcription factor T-bet, which also antagonize ST2+ Treg cells. Finally, we demonstrate that ST2+ Treg cells preserve glucose homeostasis, whereas CXCR3+ Treg cells restrain inflammation in lean VAT and prevent glucose intolerance under high-fat diet conditions. Overall, this study defines two molecularly and developmentally distinct VAT Treg cell types with unique context- and sex-specific functions.
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    A Broad-Spectrum α-Glucosidase of Glycoside Hydrolase Family 13 from Marinovum sp., a Member of the Roseobacter Clade
    Li, J ; Mui, JW-Y ; da Silva, BM ; Pires, DEV ; Ascher, DB ; Soler, NM ; Goddard-Borger, ED ; Williams, SJ (SPRINGER, 2024-01-05)
    Glycoside hydrolases (GHs) are a diverse group of enzymes that catalyze the hydrolysis of glycosidic bonds. The Carbohydrate-Active enZymes (CAZy) classification organizes GHs into families based on sequence data and function, with fewer than 1% of the predicted proteins characterized biochemically. Consideration of genomic context can provide clues to infer possible enzyme activities for proteins of unknown function. We used the MultiGeneBLAST tool to discover a gene cluster in Marinovum sp., a member of the marine Roseobacter clade, that encodes homologues of enzymes belonging to the sulfoquinovose monooxygenase pathway for sulfosugar catabolism. This cluster lacks a gene encoding a classical family GH31 sulfoquinovosidase candidate, but which instead includes an uncharacterized family GH13 protein (MsGH13) that we hypothesized could be a non-classical sulfoquinovosidase. Surprisingly, recombinant MsGH13 lacks sulfoquinovosidase activity and is a broad-spectrum α-glucosidase that is active on a diverse array of α-linked disaccharides, including maltose, sucrose, nigerose, trehalose, isomaltose, and kojibiose. Using AlphaFold, a 3D model for the MsGH13 enzyme was constructed that predicted its active site shared close similarity with an α-glucosidase from Halomonas sp. H11 of the same GH13 subfamily that shows narrower substrate specificity.
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    Ang II Promotes Cardiac Autophagy and Hypertrophy via Orai1/STIM1.
    Zheng, C-B ; Gao, W-C ; Xie, M ; Li, Z ; Ma, X ; Song, W ; Luo, D ; Huang, Y ; Yang, J ; Zhang, P ; Huang, Y ; Yang, W ; Yao, X (Frontiers Media S.A., 2021)
    The pathophysiology of cardiac hypertrophy is complex and multifactorial. Both the store-operated Ca2+ entry (SOCE) and excessive autophagy are the major causative factors for pathological cardiac hypertrophy. However, it is unclear whether these two causative factors are interdependent. In this study, we examined the functional role of SOCE and Orai1 in angiotensin II (Ang II)-induced autophagy and hypertrophy using in vitro neonatal rat cardiomyocytes (NRCMs) and in vivo mouse model, respectively. We show that YM-58483 or SKF-96365 mediated pharmacological inhibition of SOCE, or silencing of Orai1 with Orail-siRNA inhibited Ang II-induced cardiomyocyte autophagy both in vitro and in vivo. Also, the knockdown of Orai1 attenuated Ang II-induced pathological cardiac hypertrophy. Together, these data suggest that Ang II promotes excessive cardiomyocyte autophagy through SOCE/Orai1 which can be the prime contributing factors in cardiac hypertrophy.
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    Trajectory of immune evasion and cancer progression in hepatocellular carcinoma.
    Nguyen, PHD ; Wasser, M ; Tan, CT ; Lim, CJ ; Lai, HLH ; Seow, JJW ; DasGupta, R ; Phua, CZJ ; Ma, S ; Yang, J ; Suthen, SDO ; Tam, WL ; Lim, TKH ; Yeong, J ; Leow, WQ ; Pang, YH ; Soon, G ; Loh, TJ ; Wan, WK ; Chan, CY ; Cheow, PC ; Toh, HC ; Kow, A ; Dan, YY ; Kam, JH ; Iyer, S ; Madhavan, K ; Chung, A ; Bonney, GK ; Goh, BKP ; Fu, N ; Yu, VC ; Zhai, W ; Albani, S ; Chow, PKH ; Chew, V (Nature Portfolio, 2022-03-17)
    Immune evasion is key to cancer initiation and later at metastasis, but its dynamics at intermediate stages, where potential therapeutic interventions could be applied, is undefined. Here we show, using multi-dimensional analyses of resected tumours, their adjacent non-tumour tissues and peripheral blood, that extensive immune remodelling takes place in patients with stage I to III hepatocellular carcinoma (HCC). We demonstrate the depletion of anti-tumoural immune subsets and accumulation of immunosuppressive or exhausted subsets along with reduced tumour infiltration of CD8 T cells peaking at stage II tumours. Corresponding transcriptomic modification occur in the genes related to antigen presentation, immune responses, and chemotaxis. The progressive immune evasion is validated in a murine model of HCC. Our results show evidence of ongoing tumour-immune co-evolution during HCC progression and offer insights into potential interventions to reverse, prevent or limit the progression of the disease.
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    Sequential genome-wide CRISPR-Cas9 screens identify genes regulating cell-surface expression of tetraspanins
    Yang, J ; Guo, F ; San Chin, H ; Chen, GB ; Ang, CH ; Lin, Q ; Hong, W ; Fu, NY (CELL PRESS, 2023-02-28)
    Tetraspanins, a superfamily of membrane proteins, mediate diverse biological processes through tetraspanin-enriched microdomains in the plasma membrane. However, how their cell-surface presentation is controlled remains unclear. To identify the regulators of tetraspanin trafficking, we conduct sequential genome-wide loss-of-function CRISPR-Cas9 screens based on cell-surface expression of a tetraspanin member, TSPAN8. Several genes potentially involved in endoplasmic reticulum (ER) targeting, different biological processes in the Golgi apparatus, and protein trafficking are identified and functionally validated. Importantly, we find that biantennary N-glycans generated by MGAT1/2, but not more complex glycan structures, are important for cell-surface tetraspanin expression. Moreover, we unravel that SPPL3, a Golgi intramembrane-cleaving protease reported previously to act as a sheddase of multiple glycan-modifying enzymes, controls cell-surface tetraspanin expression through a mechanism associated with lacto-series glycolipid biosynthesis. Our study provides critical insights into the molecular regulation of cell-surface presentation of tetraspanins with implications for strategies to manipulate their functions, including cancer cell invasion.
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    Molecular Regulation and Oncogenic Functions of TSPAN8
    Yang, J ; Zhang, Z ; Lam, JSW ; Fan, H ; Fu, NY (MDPI, 2024-01)
    Tetraspanins, a superfamily of small integral membrane proteins, are characterized by four transmembrane domains and conserved protein motifs that are configured into a unique molecular topology and structure in the plasma membrane. They act as key organizers of the plasma membrane, orchestrating the formation of specialized microdomains called "tetraspanin-enriched microdomains (TEMs)" or "tetraspanin nanodomains" that are essential for mediating diverse biological processes. TSPAN8 is one of the earliest identified tetraspanin members. It is known to interact with a wide range of molecular partners in different cellular contexts and regulate diverse molecular and cellular events at the plasma membrane, including cell adhesion, migration, invasion, signal transduction, and exosome biogenesis. The functions of cell-surface TSPAN8 are governed by ER targeting, modifications at the Golgi apparatus and dynamic trafficking. Intriguingly, limited evidence shows that TSPAN8 can translocate to the nucleus to act as a transcriptional regulator. The transcription of TSPAN8 is tightly regulated and restricted to defined cell lineages, where it can serve as a molecular marker of stem/progenitor cells in certain normal tissues as well as tumors. Importantly, the oncogenic roles of TSPAN8 in tumor development and cancer metastasis have gained prominence in recent decades. Here, we comprehensively review the current knowledge on the molecular characteristics and regulatory mechanisms defining TSPAN8 functions, and discuss the potential and significance of TSPAN8 as a biomarker and therapeutic target across various epithelial cancers.
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    Caspase-2 does not play a critical role in cell death induction and bacterial clearance during Salmonella infection
    Engel, S ; Doerflinger, M ; Lee, AR ; Strasser, A ; Herold, MJ ; Bedoui, S ; Bachem, A (Springer Nature, 2021-12)