👤 Jonathan Phan

Chemical investigation of the soft coral Sclerophytum humesi led to the discovery of (±)-norsclerohumin A (1), a pair of enantiomeric norsesquiterpenoids possessing an unprecedented oxatricyclo[7.2.1.0 Show less

Discrete subaortic stenosis (DSS) is a congenital heart disease in which a fibrotic membrane forms below the aortic valve; the underlying cellular mechanisms are currently unknown. Since an elevated pressure gradient in the left ventricular outflow tract (LVOT) is a distinguishing feature of DSS, it is hypothesized that the membrane formation is caused by elevated wall shear stress applied to the endocardial endothelial cells (EECs) that line the LVOT, triggering fibrosis. To correlate shear stress to an EEC fibrotic phenotype, we applied fluid shear stress to EECs at physiological and pathological shear rates using a cone-and-plate device, designed to recapitulate physiological wall shear stress in a controlled in vitro environment. Controlled shear stress regimes were applied to EECs to replicate the conditions observed in DSS patients. We found that elevated shear stress triggered EEC alignment as well as endothelial-to-mesenchymal transformation (EndMT) signaling pathways driven by upregulation of SNAI1 gene expression. The EECs were then treated with a small molecule inhibitor of Snail1 protein, CYD19, to attempt to attenuate EndMT signaling, and subsequently subjected to pathological shear stress. The Snail1 inhibitor did downregulate selected markers of EndMT signaling, although only transiently. Interestingly, the application of shear stress had a greater effect on the EEC gene and protein expression than did the Snail1 inhibition. This investigation of EEC response to shear stress reveals the pronounced and complex effect of this mechanical stimulation on the EEC phenotype. Further study should reveal the mechanisms that drive fibrosis and the formation of the DSS membrane. Show less

Apolipoprotein B (APOB) rs676210 polymorphism has been associated with altered lipid metabolism and cardiovascular risk in various populations; however, data from Vietnamese populations remain limited. This study aimed to investigate the association of the APOB rs676210 variant with lipid profiles among Vietnamese individuals newly diagnosed with elevated low-density lipoprotein cholesterol (LDL-C). A cross-sectional study was conducted among 69 Vietnamese adults newly diagnosed with elevated LDL-C (≥130 mg/dL) at a tertiary hospital in Southern Vietnam. Participants were genotyped for APOB rs676210 using real-time polymerase chain reaction (PCR) with allele-specific probes. Lipid profile components, including LDL-C, high-density lipoprotein cholesterol (HDL-C), non-HDL-C, and ApoB, were compared across genotype groups (AA vs GA/GG) and alleles (A vs G). Statistical analyses involved t tests, chi-square tests, and multivariable linear regression adjusted for age, sex, the BMI, and diabetes. P<.05 was considered statistically significant. Of the 69 participants, 32 (46.4%) carried the AA genotype, while 37 (53.6%) carried the GA or the GG genotype. The AA genotype was associated with significantly higher LDL-C (mean 5.19, SD 0.95, vs mean 4.37, SD 0.97, mmol/L; P<.001), non-HDL-C (mean 5.94, SD 1.08, vs mean 5.31, SD 1.22 mmol/L; P=.03), and ApoB (mean 149.5, SD 26.3, vs mean 136.9, SD 15.2, mg/dL; P=.02) and lower HDL-C (mean 1.26, SD 0.31, vs mean 1.44, SD 0.39, mmol/L; P=.03) compared to the GA/GG genotype. Allele-based analysis showed that carriers of the A allele (98/138, 71%) also had higher LDL-C (mean 4.91, SD 1.02, vs mean 4.36, SD 0.97, mmol/L; P=.004) and ApoB (mean 145.6, SD 23.2, vs mean 135.9, SD 16.0, mg/dL; P=.02) than G allele carriers (40/138, 29%). These associations remained significant after multivariate adjustment. APOB rs676210 polymorphism is associated with significant differences in lipid profiles among Vietnamese adults with elevated LDL-C. Specifically, the A allele and the AA genotype confer a more atherogenic profile, suggesting potential utility as a genetic marker in lipid screening and personalized cardiovascular risk management in this population. Show less

Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated with trained immunity and have long-term impacts on hematopoietic stem and progenitor cell (HSPC) development but can also compromise their function. While many cytokines support emergency myelopoiesis, less is known about the mechanisms that temper these events. When mice that lack the cytokine IL-27 were infected with Show less

Regulatory T (Treg) cells express high levels of the IL-27R, and in the setting of infection and autoimmunity, the cytokine IL-27 promotes Treg cell activities that mitigate tissue pathology. However, IL-27 appears dispensable for Treg cell development and maintenance as lineage-specific depletion of the IL-27R on Treg cells does not impact these populations at steady state. In contrast, when mice were generated in which the Treg compartment comprised a mix of IL-27R-sufficient and -deficient Treg cells, those that lacked IL-27R were at a competitive disadvantage. Aging experiments illustrate that IL-27R-deficient Treg cells are preferentially eroded, and this defect was associated with reduced expression of CD122, the β chain of the IL-2/15R. Moreover, blockade of CD122 led to a similar loss of Treg cells, and in vitro and in vivo studies highlight that IL-27 promotes Treg cell expression of CD122 and improves responsiveness to IL-2/15. These datasets reveal that homeostatic IL-27 signals provide a competitive advantage that shapes the composition of the Treg cell pool by modulating responsiveness to growth factors. Show less

Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated with trained immunity and have long-term impacts on hematopoietic stem and progenitor cell (HSPC) development but can also compromise their function. While many cytokines support emergency myelopoiesis, less is known about the mechanisms that temper these events. When mice that lack the cytokine IL-27 were infected with Show less

Coronary artery disease (CAD) remains a leading cause of morbidity and mortality worldwide. Lipoprotein (a) [Lp(a)] has emerged as an independent risk factor for CAD, but its role in predicting coronary severity in Vietnamese populations remains unclear. To evaluate the value of Lp(a) in predicting the severity of coronary artery stenosis in chronic CAD. This cross-sectional study was conducted at Tam Anh General Hospital from June 2024 to June 2025, including 138 patients diagnosed with chronic CAD. Demographic, clinical, laboratory, and coronary angiographic data were collected. CAD severity was assessed using the Gensini score. Logistic regression and ROC analysis were employed to evaluate the predicting value of Lp(a). Severe CAD (Gensini score >40) was present in 31.9% of the cohort. Patients with Lp(a) ≥30 mg/dL exhibited a significantly higher prevalence of severe CAD (72.5% vs. 8.0%). Lp(a) levels correlated strongly with the Gensini score. The optimal cut-off for predicting severe CAD was 30.6 mg/dL (AUC = 0.869). Multivariate analysis confirmed Lp(a) as an independent predictor. Lp(a) ≥30 mg/dL is strongly associated with severe coronary artery stenosis. Lp(a) is a valuable independent predictor of CAD severity and may serve as an essential tool for risk stratification in clinical practice. Show less

Fibroblast-like synoviocytes (FLSs) play a crucial role in the pathogenesis of arthritis. However, the impact of small extracellular vesicles (sEVs) secreted by FLSs on osteoclastogenesis remains incompletely understood. In this study, we aimed to investigate the role of tumor necrosis factor (TNF)- and lysophosphatidic acid (LPA)-activated FLSs in sEV-mediated release of osteoclastogenic miRNAs and elucidate their functional contribution to osteoclastogenesis. Stimulation of SW982 cells with LPA or TNF significantly increased sEV secretion. TNF upregulated autotaxin expression and promoted sEV release; however, small interfering RNA (siRNA)-mediated knockdown (KD) of LPAR1 attenuated the increase in sEV release induced by the TNF-autotaxin-LPA axis. Notably, stimulation with TNF or LPA elevated syntenin-1 expression without altering its mRNA level. Furthermore, KD of the syntenin-1 gene (SDCBP) suppressed the LPA-induced increase in sEV release, indicating that syntenin-1 may mediate sEV secretion induced by the TNF-autotaxin-LPA-LPAR1 axis. sEVs derived from TNF- or LPA-treated SW982 cells stimulated osteoclastogenesis. We identified miR-31-5p as an osteoclastogenic miRNA enriched in sEVs. Expression levels of miR-31-5p in sEVs from TNF- and LPA-stimulated rheumatoid arthritis (RA) FLSs were significantly higher than in those from unstimulated RA FLSs. Treatment with a miR-31-5p mimic enhanced osteoclastogenesis by targeting large tumor suppressor kinase 2 (LATS2), whereas treatment with its inhibitor suppressed the sEV-mediated promotion of osteoclastogenesis. These findings reveal a mechanism by which TNF- and LPA-activated FLSs may facilitate sEV-mediated delivery of osteoclastogenic miRNAs, such as miR-31-5p, to osteoclast precursors, thereby contributing to osteoclast formation and bone destruction. Show less

Genetic tests are important in the classification, treatment, and prognosis of acute myeloid leukemia (AML). The present study aimed to detect genetic abnormalities and investigate the correlation between gene abnormalities and the treatment results of childhood AML. A descriptive cross-sectional study of 35 children with de novo AML was established between 2017 and 2022 at Hue Central Hospital, Vietnam. Parameters of age, gender, gene fusions, remission, relapse rate, and survival rates were investigated. The male-to-female ratio was 1.92:1. The mean age was 7.3±4.9 years. The multiplex reverse transcription polymerase chain reaction (RT-PCR) using the HemaVision 28N kit test results showed that 12 (34.3%) patients had genetic abnormalities, of which five (14.2%) patients had AML1/ETO fusion, three (8.6%) had PML/RARA fusion, two (5.7%) had MLL/AF6 fusion, one (2.9%) had KMT2A/MLLT10 fusion, and one (2.9%) had AML1/ETO and BCR/ABL1 fusion. Prognostic grouping according to genetic mutation showed eight (22.9%) patients with a favorable prognosis, 23 (65.7%) patients with an intermediate prognosis, and four (11.4%) patients with a poor prognosis. There were significant relationships between the remission rate and the genetic risk group. The remission rates for poor, intermediate, and good prognosis groups were 25%, 43.5%, and 100%, respectively. However, there were no statistical correlations between the relapse rate, the overall survival rate, and the event-free survival rate with the genetic risk group. Genetic abnormalities have a role in the classification, prognosis, and treatment of AML patients. However, treatment outcomes in AML are influenced by multiple factors beyond genetics, including infection-related complications, nutritional status, socioeconomic conditions, supportive care infrastructure, and access to intensive chemotherapy and transplant services. Supportive care plays an important role in the treatment outcome of childhood AML. Show less

Endothelial-to-mesenchymal transition (EndMT) has been implicated in inflammatory vascular pathologies such as atherosclerosis. The nonfibrillar collagen type VIII functions as a pivotal player in atherogenesis, but its role in EndMT is not well understood. We assessed the role of the α 1 chain of collagen type VIII (COL8A1) in inflammatory EndMT. Single-cell RNA-seq analysis of murine and human endothelial cells exposed to atherogenic stimuli in vivo revealed increased COL8A1 expression. Immunofluorescent analyses showed that COL8A1 expression was increased in murine atherosclerotic lesions, coinciding with the decreased expression of the endothelial marker platelet endothelial cell adhesion molecule-1. Treatment of human aortic endothelial cells (HAECs) with tumor necrosis factor-α (TNF-α) induced inflammatory EndMT. Interestingly, TNF-α treatment had a biphasic effect on COL8A1 expression in HAECs, with an initial downregulation followed by upregulation at 5 days of treatment. HAECs were then subjected to either exogenous recombinant COL8A1 (rcol8a1) exposure, lentiviral COL8A1 overexpression, or COL8A1 siRNA inhibition. Functionally, COL8A1 knockdown in HAECs suppressed endothelial gene programs, impaired tube formation, and enhanced NF-κB/Snail activation. Conversely, recombinant COL8A1 or lentiviral overexpression preserved endothelial morphology and markers and attenuated TNF-α-induced EndMT. Our findings suggest that COL8A1 is a key regulator of endothelial stability during inflammatory stress. Its transient inhibition facilitates early EndMT via NF-kB/Snail signaling, whereas its later induction in advanced disease reflects endothelial remodeling within atherosclerotic lesions. These findings identify COL8A1 as both a biomarker and a potential therapeutic target in vascular disease. Show less

The molecular characterization of male breast cancer (MaBC) has received limited attention in research, mostly because of its low incidence rate, accounting for only 0.5% to 1% of all reported cases of breast cancer each year. Managing MaBC presents significant challenges, with most treatment protocols being adapted from those developed for female breast cancer. Utilizing whole-genome sequencing (WGS) and state-of-the-art analyses, the genomic features of 10 MaBC cases (n = 10) were delineated and correlated with clinical and histopathologic characteristics. Using fluorescence in situ hybridization, an additional cohort of 18 patients was interrogated to supplement WGS findings. The genomic landscape of MaBC uncovered significant genetic alterations that could influence diagnosis and treatment. We found common somatic mutations in key driver genes, such as FAT1, GATA3, SMARCA4, and ARID2. Our study also mapped out structural variants that impact cancer-associated genes, such as ARID1A, ESR1, GATA3, NTRK1, and NF1. Using a WGS-based classifier, homologous recombination deficiency (HRD) was identified in 2 cases, both presenting with deleterious variants in BRCA2. Noteworthy was the observation of FGFR1 amplification in 21% of cases. Altogether, we identified at least 1 potential therapeutic target in 8 of the 10 cases, including high tumor mutational burden, FGFR1 amplification, and HRD. Our study is the first WGS characterization of MaBC, which uncovered potentially relevant variants, including structural events in cancer genes, HRD signatures, and germline pathogenic mutations. Our results demonstrate unique genetic markers and potential treatment targets in MaBC, thereby underlining the necessity of tailoring treatment strategies for this understudied patient population. These WGS-based findings add to the growing knowledge of MaBC genomics and highlight the need to expand research on this type of cancer. Show less

Phosphatidylinositol 4-kinase IIIα (PI4KIIIα) is the major enzyme responsible for generating phosphatidylinositol (4)-phosphate [PI(4)P] at the plasma membrane. This lipid kinase forms two multicomponent complexes, both including a palmitoylated anchor, EFR3. Whereas both PI4KIIIα complexes support production of PI(4)P, the distinct functions of each complex and mechanisms underlying the interplay between them remain unknown. Here, we present roles for differential palmitoylation patterns within a tri-cysteine motif in EFR3B (Cys5, Cys7 and Cys8) in controlling the distribution of PI4KIIIα between these two complexes at the plasma membrane and corresponding functions in phosphoinositide homeostasis. Spacing of palmitoyl groups within three doubly palmitoylated EFR3B 'lipoforms' affects both interactions between EFR3B and TMEM150A, a transmembrane protein governing formation of a PI4KIIIα complex functioning in rapid phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] resynthesis following phospholipase C signaling, and EFR3B partitioning within liquid-ordered and -disordered regions of the plasma membrane. This work identifies a palmitoylation code involved in controlling protein-protein and protein-lipid interactions that affect a plasma membrane-resident lipid biosynthetic pathway. Show less

G-quadruplex (G4) binding proteins regulate important biological processes, but their interaction networks are poorly understood. We report the first use of G4 as a warhead of a proteolysis-targeting chimera (G4-PROTAC) for targeted degradation of a G4-binding protein (RHAU/DHX36). G4-PROTAC provides a new way to explore G4-protein networks and to develop potential therapeutics. Show less

G-quadruplex (G4) is a non-canonical four-stranded nucleic acid structure and the RHAU helicase has been identified to have high specificity for recognition of parallel-stranded G4s. We have designed and synthesized two stapled peptide analogues of the G4-specfic motif of RHAU, which preserve the G4 binding ability. Characterization of these peptides identified the stapled variants to exhibit higher helical formation propensity in aqueous buffer in comparison to the native RHAU sequence. Moreover, the stapled peptides exhibit superior enzymatic stability towards α-chymotrypsin. Our stapled RHAU peptides can serve as a new tool for targeting G4 nucleic acid structures. Show less

G-quadruplexes (G4) are secondary structures of nucleic acids that can form in cells and have diverse biological functions. Several biologically important proteins interact with G-quadruplexes, of which RHAU (or DHX36) - a helicase from the DEAH-box superfamily, was shown to bind and unwind G-quadruplexes efficiently. We report a X-ray co-crystal structure at 1.5 Å resolution of an N-terminal fragment of RHAU bound to an exposed tetrad of a parallel-stranded G-quadruplex. The RHAU peptide folds into an L-shaped α-helix, and binds to a G-quadruplex through π-stacking and electrostatic interactions. X-ray crystal structure of our complex identified key amino acid residues important for G-quadruplex-peptide binding interaction at the 3'-end G•G•G•G tetrad. Together with previous solution and crystal structures of RHAU bound to the 5'-end G•G•G•G and G•G•A•T tetrads, our crystal structure highlights the occurrence of a robust G-quadruplex recognition motif within RHAU that can adapt to different accessible tetrads. Show less

We developed a ribonuclease for site-specific targeting and cleavage of single-stranded RNA. The engineered RNase protein was constructed by incorporating two independent functional domains, an RNase HI domain that could cleave the RNA strand in a DNA-RNA hybrid, and a domain of the RHAU protein that could selectively recognize a parallel DNA G-quadruplex (G4). The newly designed RNase first recruits a DNA guide oligonucleotide containing both a parallel G4 motif and a template sequence complementary to the target RNA. This RNase:DNA complex targets and efficiently cleaves the single-stranded RNA in a site-specific manner. A major cleavage site occurs at the RNA region that is complementary to the DNA template sequence. The newly designed RNase can serve as a simple tool for RNA manipulation and probing RNA structure. Show less

Multiple hereditary exostoses (MHE) is an autosomal dominant disorder that affects about 1 in 50,000 children worldwide. MHE, also known as hereditary multiple exostoses (HME) or multiple osteochondromas (MO), is characterized by cartilage-capped outgrowths called osteochondromas that develop adjacent to the growth plates of skeletal elements in young patients. These benign tumors can affect growth plate function, leading to skeletal growth retardation, or deformations, and can encroach on nerves, tendons, muscles, and other surrounding tissues and cause motion impairment, chronic pain, and early onset osteoarthritis. In about 2-5% of patients, the osteochondromas can become malignant and life threatening. Current treatments consist of surgical removal of the most symptomatic tumors and correction of the major skeletal defects, but physical difficulties and chronic pain usually continue and patients may undergo multiple surgeries throughout life. Thus, there is an urgent need to find new treatments to prevent or reverse osteochondroma formation. The 2016 International MHE Research Conference was convened to provide a forum for the presentation of the most up-to-date and advanced clinical and basic science data and insights in MHE and related fields; to stimulate the forging of new perspectives, collaborations, and venues of research; and to publicize key scientific findings within the biomedical research community and share insights and relevant information with MHE patients and their families. This report provides a description, review, and assessment of all the exciting and promising studies presented at the Conference and delineates a general roadmap for future MHE research targets and goals. Show less

Four-stranded nucleic acid structures called G-quadruplexes have been associated with important cellular processes, which should require G-quadruplex-protein interaction. However, the structural basis for specific G-quadruplex recognition by proteins has not been understood. The DEAH (Asp-Glu-Ala-His) box RNA helicase associated with AU-rich element (RHAU) (also named DHX36 or G4R1) specifically binds to and resolves parallel-stranded G-quadruplexes. Here we identified an 18-amino acid G-quadruplex-binding domain of RHAU and determined the structure of this peptide bound to a parallel DNA G-quadruplex. Our structure explains how RHAU specifically recognizes parallel G-quadruplexes. The peptide covers a terminal guanine base tetrad (G-tetrad), and clamps the G-quadruplex using three-anchor-point electrostatic interactions between three positively charged amino acids and negatively charged phosphate groups. This binding mode is strikingly similar to that of most ligands selected for specific G-quadruplex targeting. Binding to an exposed G-tetrad represents a simple and efficient way to specifically target G-quadruplex structures. Show less

For settings with limited laboratory capacity, 2013 World Health Organization (WHO) guidelines recommend targeted HIV-1 viral load (VL) testing to identify virological failure. We previously developed and validated a clinical prediction score (CPS) for targeted VL testing, relying on clinical, adherence and laboratory data. While outperforming the WHO failure criteria, it required substantial calculation and review of all previous laboratory tests. In response, we developed four simplified, less error-prone and broadly applicable CPS versions that can be done 'on the spot'. Findings From May 2010 to June 2011, we validated the original CPS in a non-governmental hospital in Phnom Penh, Cambodia applying the CPS to adults on first-line treatment >1 year. Virological failure was defined as a single VL >1000 copies/ml. The four CPSs included CPS1 with 'current CD4 count' instead of %-decline-from-peak CD4; CPS2 with hemoglobin measurements removed; CPS3 having 'decrease in CD4 count below baseline value' removed; CPS4 was purely clinical. Score development relied on the Spiegelhalter/Knill-Jones method. Variables independently associated with virological failure with a likelihood ratio ≥ 1.5 or ≤ 0.67 were retained. CPS performance was evaluated based on the area-under-the-ROC-curve (AUROC) and 95% confidence intervals (CI). The CPSs were validated in an independent dataset. A total of 1490 individuals (56.6% female, median age: 38 years (interquartile range (IQR 33-44)); median baseline CD4 count: 94 cells/µL (IQR 28-205), median time on antiretroviral therapy 3.6 years (IQR 2.1-5.1)), were included. Forty-five 45 (3.0%) individuals had virological failure. CPS1 yielded an AUROC of 0.69 (95% CI: 0.62-0.75) in validation, CPS2 an AUROC of 0.68 (95% CI: 0.62-0.74), and CPS3, an AUROC of 0.67 (95% CI: 0.61-0.73). The purely clinical CPS4 performed poorly (AUROC-0.59; 95% CI: 0.53-0.65). Simplified CPSs retained acceptable accuracy as long as current CD4 count testing was included. Ease of field application and field accuracy remains to be defined. Show less