Biology subjects

Ng, W. H.

Publications and source records attributed to Ng, W. H..

8 recordsLinked to original sources

bioRxiv2025

A pain-reducing Kv6.4 variant spares other Kv6 channels, offering a target for uterine pain

Uterine pain conditions such as dysmenorrhea and endometriosis are highly prevalent, poorly managed, and associated with long-term impacts on womens health. The identification of a rare KCNG4 variant (rs140124801; p.Val419Met) previously linked to reduced labor pain suggests Kv6.4 (encoded by KCNG4) may play a role in visceral nociception and offer a new target for non-opioid uterine pain relief. We analyzed UK Biobank data to evaluate clinical phenotypes associated with rare single nucleotide polymorphisms (SNPs) in the conserved TVGYG selectivity filter motif of the Kv6 family wherein p.Val419Met is located. Functional consequences of these variants were assessed using immunofluorescence in SHSY5Y cells to examine membrane trafficking, co-immunoprecipitation to investigate interactions between Kv6 subunits and Kv2.1, and single-cell RNA sequencing to determine expression patterns in mouse sensory neurons. Our genetic analysis identified 5,816 individuals heterozygous and 28 homozygous for the p.Val419Met variant, as well as 292 heterozygous carriers of the p.Thr418Met variant, all located in the Kv6.4 subunit. Neither variant was associated with increased risk for general, neurological, or pain-related disorders, even in homozygous p.Val419Met carriers, supporting a favorable safety profile. Kv6.4Val419Met has a dominant negative effect on wild type Kv6.4. However, this effect is specific to Kv6.4 as, in SHSY5Y cells, co-expression of Kv6.4Val419Met along with Kv6.1, Kv6.2 or Kv6.3, showed no effects on the efficient membrane localization of Kv6.1-3. In contrast, Kv6.4Thr418Met does not interfere with Kv6.4 trafficking or its heteromerization with Kv2.1. Additionally, In SHSY5Y cells, the equivalent p.Val419Met substitution, when introduced into Kv6.1, Kv6.2 and Kv6.3, disrupts their membrane localization, noting that these variants have never been reported. Co-immunoprecipitation shows that Kv6.4 does not interact with other Kv6 subunits and transcriptomic analysis shows that Kv6.4 is expressed in a distinct subset of mouse lumbar dorsal root ganglion neurons innervating pelvic organs. Our findings show that the Kv6.4Val419Met variant selectively disrupts Kv6.4 function without affecting other family members and is not linked to adverse phenotypes. This finding supports Kv6.4 as a highly selective and functionally distinct Kv6 subunit with no widespread deleterious effects on other Kv6 subunits, making it an attractive candidate for therapeutic targeting for uterine pain.

genetics↗

bioRxiv2025

Individual bumble bees have small, unique, and persistent foraging repertoires: implications for disease transmission

Generalist species forage on a variety of resources, but individual members may specialize on a smaller subset of those resources. Previous attempts to incorporate intraspecific resource specialization in models of disease spread by pollinators have assumed specialization on one flower species, completely partitioning the plant-pollinator network, and very gradual changes in specialization, over days or weeks. These assumptions have not been demonstrated empirically but are critical to model conclusions. Here, we used palynology from sequential pollen loads of individual common eastern bumble bees (Bombus impatiens) to explore their foraging preferences and how they change over time. We found individuals in a bumble bee colony exhibited unique repertoires of two to three flower species while the full-colony repertoire was up to three times larger and varied by time of year. Floral constancy of individual bees lasted roughly ten days before turning over. We developed a disease transmission model parametrized with these empirical results, finding that R0 decreased with each additional flower species in a repertoire, which reduces the separation between theorized disease transmission subnetworks. Our results provide novel insight into the foraging behaviors of social bumble bees and improves understanding of how disease transmission occurs in complex plant-pollinator networks.

ecology↗

bioRxiv2023

A time for every purpose: using time-dependent sensitivity analysis to help understand and manage dynamic ecological systems

Sensitivity analysis is often used to help understand and manage ecological systems, by assessing how a constant change in vital rates or other model parameters might affect the management outcome. This allows the manager to identify the most favorable course of action. However, realistic changes are often localized in time--for example, a short period of culling leads to a temporary increase in the mortality rate over the period. Hence, knowing when to act may be just as important as knowing what to act upon. In this article, we introduce the method of time-dependent sensitivity analysis (TDSA) that simultaneously addresses both questions. We illustrate TDSA using three case studies: transient dynamics in static disease transmission networks, disease dynamics in a reservoir species with seasonal life-history events, and endogenously-driven population cycles in herbivorous invertebrate forest pests. We demonstrate how TDSA often provides useful biological insights, which are understandable on hindsight but would not have been easily discovered without the help of TDSA. However, as a caution, we also show how TDSA can produce results that mainly reflect uncertain modeling choices and are therefore potentially misleading. We provide guidelines to help users maximize the utility of TDSA while avoiding pitfalls.

ecology↗

bioRxiv2021

Engineering 3D Vascularized Adipose Tissue Construct using a Decellularized Lung Matrix

Critically sized defects in subcutaneous white adipose tissue result in extensive disfigurement and dysfunction and remain a reconstructive challenge for surgeons; as larger defect sizes are correlated with higher rates of complications and failure due to insufficient vascularization following implantation. Our study demonstrates for the first-time a method to engineer perfusable, pre-vascularized, high-density adipose grafts that combine patient-derived adipose cells with a decellularized lung matrix (DLM). The lung is one of the most vascularized organs with high flow, low resistance, and a large blood-alveolar interface separated by a thin basement membrane. For our work, the large volume capacity within the alveolar compartment was repurposed for high-density adipose cell filling, while the acellular vascular bed provided efficient graft perfusion throughout. Both adipocytes and hASCs were successfully delivered and remained in the alveolar space even after weeks of culture. While adipose derived cells maintained their morphology and functionality in both static and perfusion DLM cultures, perfusion culture offered enhanced outcomes over static culture. Furthermore, we demonstrate that endothelial cells seamlessly integrate into the acellular vascular tree of the DLM with adipocytes. These results support that the DLM is a unique platform for creating vascularized adipose tissue grafts for large defect filling.

bioengineering↗

bioRxiv2021

Recapitulate Human Cardio-pulmonary Co-development Using Simultaneous Multilineage Differentiation of Pluripotent Stem Cells

The extensive crosstalk between the developing heart and lung is pivotal for their proper morphogenesis and maturation. However, there remains a lack of model systems for investigating the critical cardio-pulmonary mutual interaction during human embryogenesis. Here, we reported a novel stepwise strategy for directing simultaneous induction of both mesoderm-derived cardiac and endoderm-derived lung epithelial lineages within a single differentiation of human pluripotent stem cells (hPSCs) via temporal specific tuning of WNT and TGF-{beta} signaling in the absence of exogenous growth factors. Using 3D suspension culture, we established concentric cardio-pulmonary micro-Tissues (Ts), and observed expedited alveolar maturation in the presence of cardiac accompany. Upon withdrawal of WNT agonist, the cardiac and pulmonary components within each dual-lineage T effectively segregated from each other with concurrent initiation of cardiac contraction. We expect our multilineage differentiation model to offer an experimentally tractable system for investigating human cardio-pulmonary interplay and tissue boundary formation during embryogenesis.

developmental biology↗

bioRxiv2018

The Dimer-dependent Catalytic Activity of RAF Family Kinases Is Revealed Through Characterizing Their Oncogenic Mutants

Although extensively studied for three decades, the molecular mechanisms that regulate the RAF/MEK/ERK kinase cascade remain ambiguous. Recent studies identified the dimerization of RAF as a key event in the activation of this cascade. Here, we show that in-frame deletions in the {beta}3-C loop activate ARAF as well as BRAF and other oncogenic kinases by enforcing homodimerization. By characterizing these RAF mutants, we find that ARAF has less allosteric and catalytic activity than the other two RAF isoforms, which arises from its non-canonical APE motif. Further, these RAF mutants exhibit a strong oncogenic potential, and a differential inhibitor resistance that correlates with their dimer affinity. Using these unique mutants, we demonstrate that active RAFs, including the BRAF(V600E) mutant, phosphorylate MEK in a dimer-dependent manner. This study characterizes a special category of oncogenic kinase mutations, and elucidates the molecular basis that underlies the differential ability of RAF isoforms to stimulate MEK-ERK pathway. Further, this study reveals a unique catalytic feature of RAF family kinases that can be exploited to control their activities for cancer therapies.

cancer biology↗

bioRxiv2018

AMPKi overcomes the paradoxical activation of CRAF driven by RAF inhibitors through blocking the 14-3-3 binding to its carboxyl-terminus

The paradoxical activation of RAF kinase is the predominant challenge in cancer therapies with RAF inhibitors. The inhibitor-bound RAF molecules are able to transactivate their wild-type binding partners. 14-3-3 that binds to the carboxyl-terminus of RAF kinase has been suggested to regulate the dimer-dependent activation of RAF kinase under physiological conditions, though the molecular basis is not clear. In this study, we investigated the role of 14-3-3 in the paradoxical effect of RAF inhibitors. Firstly, we found that the 14-3-3 binding to the carboxyl-terminus of CRAF was essential for its transactivation. Further, we demonstrated that this binding enhanced the dimer affinity of CRAF. Since 14-3-3 binds to the phosphorylated motif, we next investigated and identified AMPK and CRAF itself as two putative kinases that phosphorylate redundantly the 14-3-3 binding motif of CRAF. Among RAF isoforms, CRAF plays a dominant role in the paradoxical effect of RAF inhibitors, and we thus determined whether the combinatory inhibition of AMPK and CRAF would block this effect. Indeed, our data showed that AMPKi not only blocked the RAF inhibitor-driven paradoxical activation of RAF signaling and cellular overgrowth in Ras-mutated cancer cells but also reduced the drug-resistant clones derived from BRAF(V600E)-mutated cancer cells. Finally, we showed that the 14-3-3 binding to the carboxyl-terminus of CRAF was dispensable for its catalytic function in vivo. Together, our study unraveled how 14-3-3 regulates the dimerization-driven RAF activation and identified AMPKi as a potential method to relieve the drug resistance and side effect of RAF inhibitors in cancer therapy.

cancer biology↗

bioRxiv2017

The Activation of MEK1 by Enhanced Homodimerization Drives Tumorigenesis

Hyperactive RAS/RAF/MEK/ERK signaling has a well-defined role in cancer biology. Aberrant pathway activation occurs mostly upstream of MEK; however, MEK mutations are prevalent in some cancer subsets. Here we show that cancer-related MEK mutants can be classified as those activated by relieving the inhibitory role of helix A, and those with in-frame deletions of {beta}3-C loop, which exhibit differential resistance to MEK inhibitors in vitro and in vivo. The {beta}3-C loop deletions activate MEK1 through enhancing homodimerization that can drive intradimer cross-phosphorylation of activation loop. Further, we demonstrate that MEK1 dimerization is required both for its activation by RAF and for its catalytic activity towards ERK. Our study identifies a novel group of MEK mutants, illustrates some key steps in RAF/MEK/ERK activation, and has important implications for the design of therapies targeting hyperactive RAS/RAF/MEK/ERK signaling in cancers.

cancer biology↗