Opto-twistronic Hall effect in a three-dimensional spiral lattice.

Studies of moiré systems have explained the effect of superlattice modulations on their properties, demonstrating new correlated phases1. However, most experimental studies have focused on a few layers in two-dimensional systems. Extending twistronics to three dimensions, in which the twist extends into the third dimension, remains underexplored because of the challenges associated with the manual stacking of layers. Here we study three-dimensional twistronics using a self-assembled twisted spiral superlattice of multilayered WS2. Our findings show an opto-twistronic Hall effect driven by structural chirality and coherence length, modulated by the moiré potential of the spiral superlattice. This is an experimental manifestation of the noncommutative geometry of the system. We observe enhanced light-matter interactions and an altered dependence of the Hall coefficient on photon momentum. Our model suggests contributions from higher-order quantum geometric quantities to this observation, providing opportunities for designing quantum-materials-based optoelectronic lattices with large nonlinearities.

Observation of plaid-like spin splitting in a noncoplanar antiferromagnet.

Spatial, momentum and energy separation of electronic spins in condensed-matter systems guides the development of new devices in which spin-polarized current is generated and manipulated1-3. Recent attention on a set of previously overlooked symmetry operations in magnetic materials4 leads to the emergence of a new type of spin splitting, enabling giant and momentum-dependent spin polarization of energy bands on selected antiferromagnets5-10. Despite the ever-growing theoretical predictions, the direct spectroscopic proof of such spin splitting is still lacking. Here we provide solid spectroscopic and computational evidence for the existence of such materials. In the noncoplanar antiferromagnet manganese ditelluride (MnTe2), the in-plane components of spin are found to be antisymmetric about the high-symmetry planes of the Brillouin zone, comprising a plaid-like spin texture in the antiferromagnetic (AFM) ground state. Such an unconventional spin pattern, further found to diminish at the high-temperature paramagnetic state, originates from the intrinsic AFM order instead of spin-orbit coupling (SOC). Our finding demonstrates a new type of quadratic spin texture induced by time-reversal breaking, placing AFM spintronics on a firm basis and paving the way for studying exotic quantum phenomena in related materials.

Molecular basis for curvature formation in SepF polymerization.

The self-assembly of proteins into curved structures plays an important role in many cellular processes. One good example of this phenomenon is observed in the septum-forming protein (SepF), which forms polymerized structures with uniform curvatures. SepF is essential for regulating the thickness of the septum during bacteria cell division. In Bacillus subtilis, SepF polymerization involves two distinct interfaces, the ß-ß and α-α interfaces, which define the assembly unit and contact interfaces, respectively. However, the mechanism of curvature formation in this step is not yet fully understood. In this study, we employed solid-state NMR (SSNMR) to compare the structures of cyclic wild-type SepF assemblies with linear assemblies resulting from a mutation of G137 on the ß-ß interface. Our results demonstrate that while the sequence differences arise from the internal assembly unit, the dramatic changes in the shape of the assemblies depend on the α-α interface between the units. We further provide atomic-level insights into how the angular variation of the α2 helix on the α-α interface affects the curvature of the assemblies, using a combination of SSNMR, cryo-electron microscopy, and simulation methods. Our findings shed light on the shape control of protein assemblies and emphasize the importance of interhelical contacts in retaining curvature.

Homozygous frameshift variant in POC1B causes male infertility with oligoasthenoteratozoospermia in human and mice.

Several different mutations in the proteome of centriole 1 centriolar protein B (POC1B) have been linked to cone dystrophy or cone-rod dystrophy (CORD). However, mutations in POC1B that are associated with both CORD and oligoasthenoteratozoospermia (OAT) have not been reported previously. Here, whole-exome sequencing was performed to identify a homozygous frameshift variant (c.151delG) in POC1B in the two brothers who had been diagnosed with both CORD and OAT from a consanguineous family. Transcript and protein analyses of biological samples from the two patients carrying the variant showed that POC1B protein is lost in sperm cells. The system CRISPR/Cas9 was utilized to create poc1bc.151delG/c.151delG knock-in (KI) mice. Notably, poc1bc.151delG/c.151delG KI male mice presented with OAT phenotype. Additionally, testicular histology and transmission electron microscopy analysis of the testes and sperm indicated that Poc1b mutation results in abnormal formation of acrosomes and flagella. Collectively, according to our experimental data on human volunteers and animal models, biallelic mutations in POC1B can cause OAT and CORD in mice and humans.

Cancer plasticity in therapy resistance: Mechanisms and novel strategies.

Therapy resistance poses a significant obstacle to effective cancer treatment. Recent insights into cell plasticity as a new paradigm for understanding resistance to treatment: as cancer progresses, cancer cells experience phenotypic and molecular alterations, corporately known as cell plasticity. These alterations are caused by microenvironment factors, stochastic genetic and epigenetic changes, and/or selective pressure engendered by treatment, resulting in tumor heterogeneity and therapy resistance. Increasing evidence suggests that cancer cells display remarkable intrinsic plasticity and reversibly adapt to dynamic microenvironment conditions. Dynamic interactions between cell states and with the surrounding microenvironment form a flexible tumor ecosystem, which is able to quickly adapt to external pressure, especially treatment. Here, this review delineates the formation of cancer cell plasticity (CCP) as well as its manipulation of cancer escape from treatment. Furthermore, the intrinsic and extrinsic mechanisms driving CCP that promote the development of therapy resistance is summarized. Novel treatment strategies, e.g., inhibiting or reversing CCP is also proposed. Moreover, the review discusses the multiple lines of ongoing clinical trials globally aimed at ameliorating therapy resistance. Such advances provide directions for the development of new treatment modalities and combination therapies against CCP in the context of therapy resistance.

Single-molecule optofluidic microsensor with interface whispering gallery modes.

Label-free sensors are highly desirable for biological analysis and early-stage disease diagnosis. Optical evanescent sensors have shown extraordinary ability in label-free detection, but their potentials have not been fully exploited because of the weak evanescent field tails at the sensing surfaces. Here, we report an ultrasensitive optofluidic biosensor with interface whispering gallery modes in a microbubble cavity. The interface modes feature both the peak of electromagnetic-field intensity at the sensing surface and high-Q factors even in a small-sized cavity, enabling a detection limit as low as 0.3 pg/cm2 The sample consumption can be pushed down to 10 pL due to the intrinsically integrated microfluidic channel. Furthermore, detection of single DNA with 8 kDa molecular weight is realized by the plasmonic-enhanced interface mode.

Multikingdom interactions govern the microbiome in subterranean cultural heritage sites.

SignificanceThe conservation of historical relics against microbial biodeterioration is critical to preserving cultural heritages. One major challenge is our limited understanding of microorganisms' dispersal, colonization, and persistence on relics after excavation and opening to external environments. Here, we investigate the ecological and physiological profiles of the microbiome within and outside the Dahuting Han Dynasty Tomb with a 1,800-y history. Actinobacteria dominate the microbiome in this tomb. Via interkingdom signaling mutualism, springtails carry Actinobacteria as one possible source into the tomb from surrounding environments. Subsequently, Actinobacteria produce cellulases combined with antimicrobial substances, which helps them to colonize and thrive in the tomb via intrakingdom competition. Our findings unravel the ecology of the microbiomes colonizing historical relics and provide help for conservation practices.

Construction of a Spatial-Confined Self-Stacking Catalytic Circuit for Rapid and Sensitive Imaging of Piwi-Interacting RNA in Living Cells.

Piwi-interacting RNAs (piRNAs) are small noncoding RNAs that repress transposable elements to maintain genome integrity. The canonical catalytic hairpin assembly (CHA) circuit relies on random collisions of free-diffused reactant probes, which substantially slow down reaction efficiency and kinetics. Herein, we demonstrate the construction of a spatial-confined self-stacking catalytic circuit for rapid and sensitive imaging of piRNA in living cells based on intramolecular and intermolecular hybridization-accelerated CHA. We rationally design a 3WJ probe that not only accelerates the reaction kinetics by increasing the local concentration of reactant probes but also eliminates background signal leakage caused by cross-entanglement of preassembled probes. This strategy achieves high sensitivity and good specificity with shortened assay time. It can quantify intracellular piRNA expression at a single-cell level, discriminate piRNA expression in tissues of breast cancer patients and healthy persons, and in situ image piRNA in living cells, offering a new approach for early diagnosis and postoperative monitoring.

Optically Triggered Emergent Mesostructures in Monolayer WS2.

The ultrahigh surface area of two-dimensional materials can drive multimodal coupling between optical, electrical, and mechanical properties that leads to emergent dynamical responses not possible in three-dimensional systems. We observed that optical excitation of the WS2 monolayer above the exciton energy creates symmetrically patterned mechanical protrusions which can be controlled by laser intensity and wavelength. This observed photostrictive behavior is attributed to lattice expansion due to the formation of polarons, which are charge carriers dressed by lattice vibrations. Scanning Kelvin probe force microscopy measurements and density functional theory calculations reveal unconventional charge transport properties such as the spatially and optical intensity-dependent conversion in the WS2 monolayer from apparent n- to p-type and the subsequent formation of effective p-n junctions at the boundaries between regions with different defect densities. The strong opto-electrical-mechanical coupling in the WS2 monolayer reveals previously unexplored properties, which can lead to new applications in optically driven ultrathin microactuators.

MLH1 Inhibits Metastatic Potential of Pancreatic Ductal Adenocarcinoma via Downregulation of GPRC5C.

DNA mismatch repair gene MutL homolog-1 (MLH1) has divergent effects in many cancers; however, its impact on the metastasis of pancreatic ductal adenocarcinoma (PDAC) remains unclear. In this study, MLH1 stably overexpressed (OE) and knockdowned (KD) sublines were established. Wound healing and transwell assays were used to evaluate cell migration/invasion. In vivo metastasis was investigated in orthotopic implantation models (severe combined immunodeficiency mice). RT-qPCR and western blotting were adopted to show gene/protein expression. MLH1 downstream genes were screened by transcriptome sequencing. Tissue microarray-based immunohistochemistry was applied to determine protein expression in human specimens. In successfully generated sublines, OE cells presented weaker migration/invasion abilities, compared with controls, whereas in KD cells, these abilities were significantly stronger. The metastasis-inhibitory effect of MLH1 was also observed in mice. Mechanistically, G protein-coupled receptor, family C, group 5, member C (GPRC5C) was a key downstream gene of MLH1 in PDAC cells. Subsequently, transient GPRC5C silencing effectively inhibited cell migration/invasion and remarkably reversed the proinvasive effect of MLH1 knockdown in KD cells. In animal models and human PDAC tissues, tumoral GPRC5C expression, negatively associated with MLH1 expressions, was positively correlated with histologic grade, vessel invasion, and poor cancer-specific survival. In conclusion, MLH1 inhibits the metastatic potential of PDAC via downregulation of GPRC5C.

USP3: Key deubiquitylation enzyme in human diseases.

Ubiquitination and deubiquitylation are pivotal posttranslational modifications essential for regulating cellular protein homeostasis and are implicated in the development of human diseases. Ubiquitin-specific protease 3 (USP3), a member of the ubiquitin-specific protease family, serves as a key deubiquitylation enzyme, playing a critical role in diverse cellular processes including the DNA damage response, cell cycle regulation, carcinogenesis, tumor cell proliferation, migration, and invasion. Despite notable research efforts, our current understanding of the intricate and context-dependent regulatory networks governing USP3 remains incomplete. This review aims to comprehensively synthesize existing published works on USP3, elucidating its multifaceted roles, functions, and regulatory mechanisms, while offering insights for future investigations. By delving into the complexities of USP3, this review strives to provide a foundation for a more nuanced understanding of its specific roles in various cellular processes. Furthermore, the exploration of USP3's regulatory networks may uncover novel therapeutic strategies targeting this enzyme in diverse human diseases, thereby holding promising clinical implications. Overall, an in-depth comprehension of USP3's functions and regulatory pathways is crucial for advancing our knowledge and developing targeted therapeutic approaches for human diseases.

LMBR1L regulates the proliferation and migration of endothelial cells through Norrin/ß-catenin signaling.

Precise Norrin and ß-catenin (Norrin/ß-catenin; encoded by NDP and CTNNB1, respectively) signaling is critical for proper angiogenesis. Dysregulation of this signaling leads to various diseases, of which retinal exudative vitreoretinopathy is the most prevalent. Here, we used a global knockout mouse model to show that limb development membrane protein 1 like (LMBR1L), a transmembrane protein of unknown function in angiogenesis, is essential for retinal vascular development. In vitro experiments revealed that LMBR1L depletion results in aberrant activation of the Norrin/ß-catenin signaling pathway via decreased ubiquitylation of FZD4 and increased Norrin co-receptor LRP5 and p-GSK3ß-Ser9 expression levels, which cause accumulation of ß-catenin. Moreover, inhibition of LMBR1L in human retinal microvascular endothelial cells (HRECs) caused increased proliferation ability and defective cell migration, which might have occurred as a result of upregulated expression levels of the apical junction components. Treatment with p-GSK3ß-Ser9 inhibitor AR-A014418 restored the phenotypes in LMBR1L-null HRECs, which further demonstrated the important regulatory role of LMBR1L in the Norrin/ß-catenin signaling pathway. Taken together, our data reveal an essential role for LMBR1L in angiogenesis. This article has an associated First Person interview with the first author of the paper.

Construction of an Enzymatically Controlled DNA Nanomachine for One-Step Imaging of Telomerase in Living Cells.

Telomerase is a basic reverse transcriptase that maintains the telomere length in cells, and accurate and specific sensing of telomerase in living cells is critical for medical diagnostics and disease therapeutics. Herein, we demonstrate for the first time the construction of an enzymatically controlled DNA nanomachine with endogenous apurinic/apyrimidinic endonuclease 1 (APE1) as a driving force for one-step imaging of telomerase in living cells. The DNA nanomachine is designed by rational engineering of substrate probes and reporter probes embedded with an enzyme-activatable site (i.e., AP site) and their subsequent assembly on a gold nanoparticle (AuNP). Upon recognition and cleavage of the AP site in the substrate probe by APE1, the loop of the substrate probe unfolds, exposing telomeric primer (TP) with the 3'-OH end. Subsequently, the TP is elongated by telomerase at the 3'-OH end to generate a long telomeric product. The resultant telomeric product acts as a swing arm that can hybridize with a reporter probe to initiate the APE1-powered walking reaction, ultimately generating a significantly enhanced fluorescence signal. Notably, endogenous APE1 is used as the driving force of the DNA nanomachine, avoiding the introduction of exogenous auxiliary cofactors into the cellular microenvironment. Owing to the high kinetics and high amplification efficiency of the APE1-powered DNA nanomachine, this strategy enables one-step sensitive sensing of telomerase in vitro and in vivo. It can successfully discriminate telomerase activity between cancer cells and normal cells, screen telomerase inhibitors, and monitor the variations of telomerase activity in living cells, offering a prospective platform for molecular diagnostics and drug discovery.

Natural compound Byakangelicin suppresses breast tumor growth and motility by regulating SHP-1/JAK2/STAT3 signal pathway.

Byakangelicin mostly obtained from the root of Angelica dahurica and has protective effect on liver injury and fibrosis. In addition, Byakangelicin, as a traditional medicine, is also used to treat colds, headache and toothache. Recent studies have shown that Byakangelicin exhibits anti-tumor function; however, the role of Byakangelicin in breast tumor progression and related mechanism has not yet been elucidated. Our study aims to investigate the role of Byakangelicin in breast tumor progression and the underlying mechanism. To measure the effect of Byakangelicin on JAK2/STAT3 signaling, a dual luciferase reporter assay and a Western blot assay were performed. CCK8, colony formation, apoptosis and cell invasion assays were used to examine the inhibitory potential of Byakangelicin on breast cancer cells. Additionally, SHP-1 was silenced by specific siRNA duplex and the function of SHP-1 on Byakangelicin-mediated inhibition of JAK2/STAT3 signaling was evaluated. Byakangelicin treatment significantly inhibited STAT3 transcriptional activity. In addition, Byakangelicin treatment blocked JAK2/STAT3 signaling in a dose-dependent manner. Byakangelicin-treated tumor cells showed a dramatically reduced proliferation, colony formation and invasion ability. Moreover, Byakangelicin remarkedly induced breast cancer cell apoptosis. Furthermore, Byakangelicin regulated the expression of SHP1.In conclusion, our current study indicated that Byakangelicin, a natural compound, inhibits SHP-1/JAK2/STAT3 signaling and thus blocks tumor growth and motility.

HDAC1 and FOXK1 mediate EGFR-TKI resistance of non-small cell lung cancer through miR-33a silencing.

BACKGROUND: The development of acquired EGFR-TKI treatment resistance is still a major clinical challenge in the treatment of non-small cell lung cancer (NSCLC). This study aimed to investigate the role of HDAC1/FOXK1/miR-33a signaling in EGFR-TKI resistance. METHODS: The expression levels of miR-33a, HDAC1, and FOXK1 were examined using quantitative polymerase chain reaction (PCR) and bioinformatics analysis. Cell proliferation, migration, and apoptosis were explored by cell number assay, Transwell, and flow cytometry assays, respectively. After overexpression or knockdown of HDAC1, miR-33a expression in the cells, cell functions were tested. Immunoprecipitation and correlation analyses were used to evaluate the interaction between HDAC1 and FOXK1 protein. The tumor-suppressive role of miR-33a was investigated by animal experiments. RESULTS: The suppression of miR-33a increased TKI resistance by affecting cell proliferation, migration, and apoptosis in gefitinib-resistant cells. HDAC1 is the key upstream molecule that inhibits miR-33 expression. HDAC1 upregulation increased gefitinib resistance by its binding to FOXK1 in cells to silence miR-33a expression. MiR-33a overexpression exerts tumor-suppressive effects by negatively regulating ABCB7 and p70S6K1 expression. Moreover, overexpression of miR-33a inhibited tumor growth in a xenograft nude mouse model. CONCLUSIONS: HDAC1/FOXK1 upregulation and miR-33a silencing are new mechanisms of EGFR-TKI resistance in NSCLC.

Association of ankylosing spondylitis with the risk of cancer: a meta- analysis of cohort studies.

OBJECTIVES: The potential impact of ankylosing spondylitis (AS) on cancer risk remains unclear. This study seeks to investigate the relationship between AS and different types of cancers. METHODS: A literature search of the PubMed, Embase and Cochrane Library up to July 10th, 2023, was conducted. Two investigators selected eligible studies and extracted relevant data. The study used the random-effects model to explore the causality between AS and cancer, utilising relative risk (RR) as a measure for the study. RESULTS: A total of 20 cohorts with >330 000 participants were included. The pooling analysis shows AS being associated with a higher risk of cancers (RR = 1.16, 95% CI : 1.07-1.26, p= 0.001, I2=70.60%). In the subgroup analysis, AS has a higher cancer risk in Asia, but this association is not significant in Europe. Individual investigations indicate that AS is associated with an increased risk of bone cancer (RR = 3.41, 95% CI : 1.45-7.99, p= 0.005, I2=0.00%), thyroid gland cancer (RR = 1.76, 95% CI : 1.29-2.40, p< 0.001, I2=13.70%), multiple myeloma (RR = 1.74, 95% CI : 1.42-2.15, p< 0.001, I2=27.20%), leukaemia (RR = 1.52, 95% CI : 1.27-1.82, p< 0.001, I2=0.00%), kidney cancer (RR = 1.45, 95% CI : 1.08-1.94, p= 0.014, I2=0.00%), prostate cancer (RR = 1.43, 95% CI : 1.17-1.74, p< 0.001, I2=82.80%), and non-Hodgkin's lymphoma (RR = 1.42, 95% CI : 1.17-1.73, p< 0.001, I2=0.00%). However, there is no significant correlation with connective tissue cancer, brain cancer, testicular and other male cancers, bladder cancer, female cancers, skin cancer, and cancers of the digestive system and respiratory system. CONCLUSION: AS appears to be related to cancer development. The results highlighted the necessity for large-scale studies, considering influencing factors such as AS course, medication histories, and potential biases when examining cancer risk.

Robotic Versus Laparoscopic Pancreaticoduodenectomy for Pancreatic Cancer: Evaluation and Analysis of Surgical Efficacy.

BACKGROUND: Evidence is limited for the treatment of pancreatic cancer among minimally invasive pancreatoduodenectomy. METHODS: This retrospective analysis evaluated patients who underwent robotic pancreaticoduodenectomy (RPD) or laparoscopic pancreaticoduodenectomy (LPD) from April 2016 to April 2023. Their baseline and perioperative data, including operative time, R0 resection rates, and severe complications rates, were analyzed, and the follow-up data, such as disease-free survival (DFS) and overall survival (OS), were collected. RESULTS: A total of 253 cases of LPD and RPD were performed, and 101 cases with pancreatic cancer were included, of which 54 were LPD and 47 were RPD. The conversion rate (4.3% vs. 29.6%, p = 0.001) and blood loss (400 vs. 575 mL, p < 0.05) were lower in the RPD group. No significant difference was observed between the two groups in terms of operative time, vessel resection rates, and TNM-stage diagnosis; however, R0 resection rates (80.9% vs. 70.4%) and lymph node harvest (24.2 vs. 21.9) had a higher tendency in the RPD group, and postoperative length of stay was shorter in the RPD cohort (11 vs. 13 days). Moreover, improved 1- to 3-years DFS (75.7%, 61.7%, and 36.0% vs. 59.0%, 35.6%, and 21.9%) and OS (94.7%, 84.7%, and 50.8% vs. 84.1%, 63.6%, and 45.5%) was found in the RPD group in comparison with the LPD group. CONCLUSIONS: RPD had advantages in surgical safety and oncological outcomes compared with LPD, but was similar to the latter in perioperative outcomes. Long-term outcomes require further study.

The sEVs miR-487a/Notch2/GATA3 axis promotes osteosarcoma lung metastasis by inducing macrophage polarization toward the M2-subtype.

Small extracellular vesicles (sEVs) are important mediators of intercellular communication between tumor cells and their surrounding environment. Furthermore, the mechanisms by which miRNAs carried in tumor sEVs regulate macrophage polarization remain largely unknown. To concentrate sEVs, we used the traditional ultracentrifugation method. Western blot, NanoSight, and transmission electron microscopy were used to identify sEVs. To determine the function of sEVs-miR-487a, we conducted in vivo and in vitro investigations. The intercellular communication mechanism between osteosarcoma cells and M2 macrophages, mediated by sEVs carrying miR-487a, was validated using luciferase reporter assays, transwell assays, and Western blot analysis. In vitro, sEVs enriched in miR-487a and delivered miR-487a to macrophages, promoting macrophage polarization toward an M2-like type, which promotes proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. In vivo, sEVs enriched in miR-487a facilitate lung metastasis of osteosarcoma. Moreover, plasma miR-487a in sEVs was shown to be a potential biomarker applicable for osteosarcoma diagnosis. In summary, miR-487a derived from osteosarcoma cells can be transferred to macrophages via sEVs, then promote macrophage polarization towards an M2-like type by targeting Notch2 and activating the GATA3 pathway. In a feedback loop, the activation of macrophages accelerates epithelial-mesenchymal transition (EMT), which in turn promotes the migration, invasion, and lung metastasis of osteosarcoma cells. This reciprocal interaction between activated macrophages and osteosarcoma cells contributes to the progression of the disease. Our data demonstrate a new mechanism that osteosarcoma tumor cells derived exosomal-miR-487a which is involved in osteosarcoma development by regulating macrophage polarization in tumor microenvironment (TME).

Engineering Dispersive-Dissipative Modal Coupling in Hybrid Optical Microresonators.

Hybrid microresonators have served an intriguing platform for fundamental research and applied photonics. Here, we study the plasmonics-engineered coupling between degenerate optical whispering gallery modes, which can be tuned in a complex space featuring the dissipative strong, dispersive strong, and weak coupling regimes. Experimentally, the engineering of a single plasmonic resonance to a cavity mode family is examined in a waveguide-integrated high-Q microdisk, from which the complex coupling coefficients are extracted and agree well with theoretical predictions. The coupling strength over 10 GHz is achieved for both dissipative and dispersive interactions, showing a remarkable enhancement compared to that induced by a dielectric scatterer. Furthermore, the far fields of hybridized cavity modes are measured, revealing the coherent interference between the radiative channels. Our results shed light on the engineering of whispering gallery modes through plasmonic resonances, and provide fundamental guidance to practical microcavity devices.

The interaction between the costimulatory molecules CD80/86 and CD28 contributed to CD4+ T lymphocyte activation in flounder (Paralichthys olivaceus).

CD28 and CD80/86 are crucial co-stimulatory molecules for the T cell activation. Previous study illustrated that CD28 and CD80/86 present on T cells and antigen-presenting cells in flounder (Paralichthys olivaceus), respectively. The co-stimulatory molecules were closely associated with cell immunity. In this paper, recombinant protein of flounder CD80/86 (rCD80/86) and phytohemagglutinin (PHA) were added to peripheral blood leukocytes (PBLs) in vitro. Lymphocytes were significantly proliferated with CFSE staining, and the proportion of CD4+ and CD28+ lymphocytes significantly increased. In the meantime, genes related to the CD28-CD80/86 signaling pathway or T cell markers were significantly upregulated (p < 0.05). For further study, the interaction between CD80/86 and CD28 was confirmed. The plasmid of CD28 (pCD28-FLAG and pVN-CD28) or CD80/86 (pVC-CD80/86) was successfully constructed. In addition, pVN-ΔCD28 without the conserved motif "TFPPPF" was constructed. The results showed that bands of pCD28-FLAG bound to rCD80/86 were detected by both anti-FLAG and anti-CD80/86. pVN-CD28 complemented to pVC-CD80/86 showing positive fluorescent signals, and pVN-ΔCD28 failed to combine with pVC-CD80/86. The motif "TFPPPF" in CD28 played a crucial role in this linkage. These results indicate that CD28 and CD80/86 molecules interact with each other, and their binding may modulate T lymphocytes immune response in flounder. This study proved the existence of CD28-CD80/86 signaling pathway in flounder.