The anterior chamber of the eye technology and its anatomical, optical, and immunological bases.

The anterior chamber of the eye (ACE) is distinct in its anatomy, optics, and immunology. This guarantees that the eye perceives visual information in the context of physiology even when encountering adverse incidents like inflammation. In addition, this endows the ACE with the special nursery bed iris enriched in vasculatures and nerves. The ACE constitutes a confined space enclosing an oxygen/nutrient-rich, immune-privileged, and less stressful milieu as well as an optically transparent medium. Therefore, aside from visual perception, the ACE unexpectedly serves as an excellent transplantation site for different body parts and a unique platform for noninvasive, longitudinal, and intravital microimaging of different grafts. On the basis of these merits, the ACE technology has evolved from the prototypical through the conventional to the advanced version. Studies using this technology as a versatile biomedical research platform have led to a diverse range of basic knowledge and in-depth understanding of a variety of cells, tissues, and organs as well as artificial biomaterials, pharmaceuticals, and abiotic substances. Remarkably, the technology turns in vivo dynamic imaging of the morphological characteristics, organotypic features, developmental fates, and specific functions of intracameral grafts into reality under physiological and pathological conditions. Here we review the anatomical, optical, and immunological bases as well as technical details of the ACE technology. Moreover, we discuss major achievements obtained and potential prospective avenues for this technology.

Misregulation of MYB16 expression causes stomatal cluster formation by disrupting polarity during asymmetric cell divisions.

Stomatal pores and the leaf cuticle regulate evaporation from the plant body and balance the tradeoff between photosynthesis and water loss. MYB16, encoding a transcription factor involved in cutin biosynthesis, is expressed in stomatal lineage ground cells, suggesting a link between cutin biosynthesis and stomatal development. Here, we show that the downregulation of MYB16 in meristemoids is directly mediated by the stomatal master transcription factor SPEECHLESS (SPCH) in Arabidopsis thaliana. The suppression of MYB16 before an asymmetric division is crucial for stomatal patterning, as its overexpression or ectopic expression in meristemoids increased stomatal density and resulted in the formation of stomatal clusters, as well as affecting the outer cell wall structure. Expressing a cutinase gene in plants ectopically expressing MYB16 reduced stomatal clustering, suggesting that cutin affects stomatal signaling or the polarity setup in asymmetrically dividing cells. The clustered stomatal phenotype was rescued by overexpressing EPIDERMAL PATTERNING FACTOR2, suggesting that stomatal signaling was still functional in these plants. Growing seedlings ectopically expressing MYB16 on high-percentage agar plates to modulate tensile strength rescued the polarity and stomatal cluster defects of these seedlings. Therefore, the inhibition of MYB16 expression by SPCH in the early stomatal lineage is required to correctly place the polarity protein needed for stomatal patterning during leaf morphogenesis.

Let-7 underlies metformin-induced inhibition of hepatic glucose production.

SignificanceA clear mechanistic understanding of metformin's antidiabetic effects is lacking. This is because suprapharmacological concentrations of metformin have been used in most studies. Using mouse models and human primary hepatocytes, we show that metformin, at clinically relevant doses, suppresses hepatic glucose production by activating a conserved regulatory pathway encompassing let-7, TET3, and a fetal isoform of hepatocyte nuclear factor 4 alpha (HNF4α). We demonstrate that metformin no longer has potent antidiabetic actions in a liver-specific let-7 loss-of-function mouse model and that hepatic delivery of let-7 ameliorates hyperglycemia and improves glucose homeostasis. Our results thus reveal an important role of the hepatic let-7/TET3/HNF4α axis in mediating the therapeutic effects of metformin and suggest that targeting this axis may be a potential therapeutic for diabetes.

Homocysteine-potentiated Kelch-like ECH-associated protein 1 promotes senescence of neuroblastoma 2a cells via inhibiting ubiquitination of ß-catenin.

Elevated serum homocysteine (Hcy) level is a risk factor for Alzheimer's disease (AD) and accelerates cell aging. However, the mechanism by which Hcy induces neuronal senescence remains largely unknown. In this study, we observed that Hcy significantly promoted senescence in neuroblastoma 2a (N2a) cells with elevated ß-catenin and Kelch-like ECH-associated protein 1 (KEAP1) levels. Intriguingly, Hcy promoted the interaction between KEAP1 and the Wilms tumor gene on the X chromosome (WTX) while hampering the ß-catenin-WTX interaction. Mechanistically, Hcy attenuated the methylation level of the KEAP1 promoter CpG island and activated KEAP1 transcription. However, a slow degradation rate rather than transcriptional activation contributed to the high level of ß-catenin. Hcy-upregulated KEAP1 competed with ß-catenin to bind to WTX. Knockdown of both ß-catenin and KEAP1 attenuated Hcy-induced senescence in N2a cells. Our data highlight a crucial role of the KEAP1-ß-catenin pathway in Hcy-induced neuronal-like senescence and uncover a promising target for AD treatment.

Postnatal treatment and evolution patterns of giant fetal hepatic hemangioma: a case series of 29 patients.

OBJECTIVES: To explore the clinical characteristics, postnatal treatment and prognosis of giant fetal hepatic hemangioma (GFHH). METHOD: Retrospective analysis was performed on children with giant fetal hepatic hemangioma (maximum tumor diameter > 40 mm) diagnosed by prenatal ultrasound and MRI from December 2016 to December 2020. These patients were observed and treated at the Children's Hospital of Fudan University after birth. The clinical data were collected to analyze the clinical characteristics, treatment, and prognosis of GFHH using independent sample t tests or Fisher's exact tests. RESULTS: Twenty-nine patients who were detected by routine ultrasound in the second and third trimester of pregnancy with giant fetal hepatic hemangiomas were included. The first prenatal ultrasound diagnosis of gestational age was 34.0 ± 4.3 weeks, ranging from 22 to 39 weeks. Of the patients, 28 had focal GFHHs and 1 had multifocal GFHHs. Surgery was performed, and the diagnosis was confirmed histopathologically in two patients. There were 8 cases with echocardiography-based evidence of pulmonary hypertension, 11 cases had a cardiothoracic ratio > 0.6, and 4 cases had hepatic arteriovenous fistula (AVF). The median follow-up time was 37 months (range: 14-70 months). During the follow-up, 12 patients received medical treatment with propranolol as the first-line therapy. The treatment group had a higher ratio of cardiothoracic ratio > 0.6 (P = 0.022) and lower albumin levels (P = 0.018). Four (14.8%) lesions showed postnatal growth before involuting. Complete response was observed in 13 (13/29) patients, and partial response was observed in 16 (16/29) patients. CONCLUSIONS: Fetal giant hepatic hemangioma is mainly localized, and its clinical outcome conforms to RICH (rapidly involuting) and PICH (partially involuting), but some fetal giant hepatic hemangiomas will continue to grow after birth and then gradually decrease. For uncomplicated giant fetal hepatic hemangioma, postnatal follow-up is the main concern, while those with complications require aggressive medical treatment. Propranolol may have no effect on the volume change of GFHH.

Clinical implications of frailty in peritoneal dialysis patients - A prospective observational study.

BACKGROUND: Frailty is an age-related condition that predicts adverse outcomes. The study was aimed to investigate the clinical implications of frailty evolution in patients undergoing peritoneal dialysis (PD). METHOD: In this prospective study, all new-onset (<6 months) and prevalent (≧6 months) PD patients completed frailty assessment at entry and 6 months by a semiautomated frailty index of 80 risk factors (FI80) which also contained the 5 components of Fried frailty phenotype. A score ≧13/80 (FI80 > 0.16) or ≧3/5 (frailty phenotype) was designated to define frailty. RESULT: 337 PD patients were recruited (new-onset 23.4%, prevalent 76.6%). Two hundred (59.3%) and 163 (48.4%) patients were frail by FI80 and frailty phenotype, respectively. Predictors for frailty were old age, dialysis, diabetes mellitus, gout and sleep disorder. New-onset patients aged <55 years displayed the best evolution of frailty over 6 months (stable or improved, n = 29/47, 61.7% by FI80, p = 0.0293), compared with other groups. Survival analysis found that frail patients exhibited the worse outcomes (overall death and hospitalization). Poisson regression showed frailty was associated with increased utilizations of outpatient and ER services; however multivariate Cox models identified only diabetes, gout and low body mass index (<19 kg/m2), but not frailty, predicted overall death and hospitalizations. CONCLUSION: Frailty is a common medical condition in PD patients, and the status of which can be stabilized or improved in new-onset, young patients at least over the short term. Compared with frailty, certain comorbidities (diabetes and gout) and undernutrition appeared to be more robust in the prediction of adverse outcomes.

Biportal Endoscopic Spinal Cord Stimulation Paddle Lead Implantation: Technical Note and Preliminary Clinical Results.

OBJECTIVE: This study aims to elucidate a novel, minimally invasive surgical technique using a biportal endoscope for the implantation of spinal cord stimulation (SCS) paddle leads and to report the preliminary results of its clinical application. MATERIALS AND METHODS: The perioperative data of patients who underwent the biportal endoscopic SCS paddle lead implantation in our department were collected; the surgical procedure was delineated, and the clinical outcomes were assessed. RESULTS: From February 2022 to December 2023, six patients underwent biportal endoscopic SCS paddle lead implantation. The median follow-up time was nine months (range one to three months). The median intraoperative blood loss was 30 mL (range 25-50 mL), and the median operative time was 87.5 minutes (range 75-110 minutes). One patient experienced severe neck pain during the operation, whereas the other five patients experienced no surgical complications. One patient was found to have a slight lead migration three months after surgery, which did not affect the therapeutic effect. The median visual analogue scale (VAS) of the surgical area was 0.5 (range 0-2), 2.5 (range 1-4), and 0.5 (range 0-1) during the operation and one day and one week after the operation, respectively. The median VAS of the six patients' primary disease was 8 (range 7-9) before surgery and 2.5 (range 1-4) at the last postoperative follow-up (pain reduction ≥50%). CONCLUSION: Paddle lead systems for SCS can be implanted successfully using a biportal endoscopic technique.

Characterization of driving factors for the long-term succession of bloom-forming cyanobacterial genera in Lake Erhai, southwest China.

Cyanobacterial blooms pose a global environmental concern, with various genera contributing to their formation. The harmfulness of cyanobacterial blooms varies depending on the specific genus, yet the factors triggering their formation remain incompletely understood. This study conducted qPCR of sediment DNA in Lake Erhai to reconstruct the historical succession of three common bloom-forming cyanobacterial genera (i.e., Microcystis, Dolichospermum, and Aphanizomenon). The driving factors and their corresponding thresholds were identified, and human activities related to driving factors were evaluated. The results revealed two successions in the past century. The first succession transitioned from Aphanizomenon (1902-1978) to Microcystis and Dolichospermum (1978-1999), driven by TN:TP and TP. The second succession shifted from Microcystis and Dolichospermum (1978-1999) to Microcystis (1999-2010), driven by TP, TN:TP, and temperature. The thresholds of TP and TN:TP for the Microcystis bloom were 0.023 mg/L and 17, respectively. TN:TP was significantly influenced by domestic pollution and crop farming in both successions, while TP was significantly impacted by domestic pollution in the first succession and by pollution from crop and dairy farming in the second succession. These results shed light on the underlying mechanism responsible for the blooms of various cyanobacterial genera and could serve as a valuable reference for effectively preventing and controlling nutrient input in the watershed.

[Endoplasmic reticulum quality control system: a potential target for the treatment of intervertebral disc degeneration].

As the largest organelle in eukaryotic cells, the endoplasmic reticulum (ER) plays a crucial role in regulating intracellular protein folding, translation and assembly. Multiple quality control mechanisms in the ER ensure accurate modification of proteins in the ER lumen are accurately modified, thus maintaining calcium homeostasis, oxidative stress, cellular senescence and apoptosis. These mechanisms include ER stress (ERS), ER autophagy (ER-phagy, ERPA) and ER-associated degradation (ERAD). Intervertebral disc degeneration (IDD) is an age-related degenerative disease of the spine. Although the pathogenesis of IDD has not been fully elucidated, emerging evidence suggests that the ER quality control system may be involved in its progression. Previous studies have focused on mitochondrial quality control and its related mechanisms in diseases, with limited systematic summaries on the ER quality control system. In this paper, we comprehensively reviewed the molecular mechanisms of the ER quality control system and investigated its association with IDD. In addition, we summarized the potential therapeutic strategies targeting the ER quality control system to attenuate IDD progression, offering new insights into the pathogenesis and regenerative repair strategies of IDD.

Catalytic Asymmetric Hydroalkoxylation and Formal Hydration and Hydroaminoxylation of Conjugated Dienes.

The straightforward construction of stereogenic centers bearing unprotected functional groups, as in nature, has been a persistent pursuit in synthetic chemistry. Abundant applications of free enantioenriched allyl alcohol and allyl hydroxylamine motifs have made the asymmetric hydration and hydroaminoxylation of conjugated dienes from water and hydroxylamine, respectively, intriguing and efficient routes that have, however, been unachievable thus far. A fundamental challenge is the failure to realize transition-metal-catalyzed enantioselective C-O bond constructions via hydrofunctionalization of conjugated dienes. Here, we perform a comprehensive study toward the stereoselective formal hydration and hydroaminoxylation of conjugated dienes by synthesizing a set of new P,N-ligands and identifying an aryl-derived oxime as a surrogate for both water and hydroxylamine. Asymmetric hydroalkoxylation with new P,N-ligands is also elucidated. Furthermore, versatile derivatizations following hydration provide indirect but concise routes to formal hydrophenoxylation, hydrofluoroalkoxylation, and hydrocarboxylation of conjugated dienes that have been unreported thus far. Finally, a ligand-to-ligand hydrogen transfer process is proposed based on the results of preliminary mechanistic experiments.

Immunogenic hypofractionated radiotherapy sensitising head and neck squamous cell carcinoma to anti-PD-L1 therapy in MDSC-dependent manner.

BACKGROUND: Enhancing the response rate of immunotherapy will aid in the success of cancer treatment. Here, we aimed to explore the combined effect of immunogenic radiotherapy with anti-PD-L1 treatment in immunotherapy-resistant HNSCC mouse models. METHODS: The SCC7 and 4MOSC2 cell lines were irradiated in vitro. SCC7-bearing mice were treated with hypofractionated or single-dose radiotherapy followed by anti-PD-L1 therapy. The myeloid-derived suppressive cells (MDSCs) were depleted using an anti-Gr-1 antibody. Human samples were collected to evaluate the immune cell populations and ICD markers. RESULTS: Irradiation increased the release of immunogenic cell death (ICD) markers (calreticulin, HMGB1 and ATP) in SCC7 and 4MOSC2 in a dose-dependent manner. The supernatant from irradiated cells upregulated the expression of PD-L1 in MDSCs. Mice treated with hypofractionated but not single-dose radiotherapy were resistant to tumour rechallenge by triggering ICD, when combined with anti-PD-L1 treatment. The therapeutic efficacy of combination treatment partially relies on MDSCs. The high expression of ICD markers was associated with activation of adaptive immune responses and a positive prognosis in HNSCC patients. CONCLUSION: These results present a translatable method to substantially improve the antitumor immune response by combining PD-L1 blockade with immunogenic hypofractionated radiotherapy in HNSCC.

High SNHG expression may predict a poor lung cancer prognosis based on a meta-analysis.

BACKGROUND: An increasing number of small nucleolar RNA host genes (SNHGs) have been revealed to be dysregulated in lung cancer tissues, and abnormal expression of SNHGs is significantly correlated with the prognosis of lung cancer. The purpose of this study was to conduct a meta-analysis to explore the correlation between the expression level of SNHGs and the prognosis of lung cancer. METHODS: A comprehensive search of six related databases was conducted to obtain relevant literature. Relevant information, such as overall survival (OS), progression-free survival (PFS), TNM stage, lymph node metastasis (LNM), and tumor size, was extracted. Hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled to evaluate the relationship between SNHG expression and the survival outcome of lung cancers. Sensitivity and publication bias analyses were performed to explore the stability and reliability of the overall results. RESULTS: Forty publications involving 2205 lung cancer patients were included in this meta-analysis. The pooled HR and 95% CI values indicated a significant positive association between high SNHG expression and poor OS (HR: 1.890, 95% CI: 1.595-2.185), disease-free survival (DFS) (HR: 2.31, 95% CI: 1.57-3.39) and progression-free survival (PFS) (HR: 2.01, 95% CI: 0.66-6.07). The pooled odds ratio (OR) and 95% CI values indicated that increased SNHG expression may be correlated with advanced TNM stage (OR: 1.509, 95% CI: 1.267-1.799), increase risk of distant lymph node metastasis (OR: 1.540, 95% CI: 1.298-1.828), and large tumor size (OR: 1.509, 95% CI: 1.245-1.829). Sensitivity analysis and publication bias results showed that each result had strong reliability and robustness, and there was no significant publication bias or other bias. CONCLUSION: Most SNHGs are upregulated in lung cancer tissues, and high expression of SNHGs predicts poor survival outcomes in lung cancer. SNHGs may be potential prognostic markers and promising therapeutic targets.

Factors associated with non-lifting of colorectal mucosal lesions.

BACKGROUND: Endoscopic submucosal dissection (ESD) is an effective treatment for colorectal tumors. However, lesions that cannot be lifted after submucosal injection are not indication for ESD. This is because the procedure is difficult, and the lesions are often considered as tumor invasion or submucosal fibrosis. The aims of this study are to evaluate the efficacy and safety of ESD for non-lifting lesions and to analyze the causes of non-lifting phenomenon. METHODS: This retrospective study included 29 patients with non-lifting colon lesions resected by ESD from February 2018 to September 2021. Cases were observed for demographics, endoscopic findings, treatment outcomes, adverse events and endoscopic follow-up. We studied the pathological features of lesions to explore the reasons for non-lifting. RESULTS: Among 29 cases of non-lifting lesions, 20 lesions (69.0%) were 30 mm in diameter or larger. Most of lesions (96.6%) were non-lifting in center, and only one lesions (3.4%) had non-lifting of one side. The en bloc and curative resection rates of ESD were 100 and 86.2%, respectively. There was one (3.4%) delayed bleeding, no perforations and other complications. No tumor recurrence occurred during the follow-up period. For pathological features, 16 (55.2%) non-lifting lesions had submucosal fibrosis and only 4 cases (13.8%) had deep submucosal invasion. There were 9 cases (31.0%) of non-lifting lesions due to musculo-fibrous of muscularis propria anomaly (MMPA). CONCLUSION: MMPA is another reason for non-lifting signs besides invasive carcinomas and submucosal fibrosis. ESD should be considered in patients with large non-lifting adenoma instead of surgery.

The Effect of Peri-Device Leaks on Ischaemic Stroke/Transient Ischaemic Attack/Systemic Embolism after Left Atrial Appendage Closure: A Systematic Review and Meta-Analysis.

BACKGROUND: Left atrial appendage closure (LAAC) is a safe and effective method for preventing embolic events in patients with non-valvular atrial fibrillation. However, peri-device leaks (PDLs) are sometimes unavoidable. Controversy exists regarding whether PDLs lead to embolic events. OBJECTIVES: This study aimed to explore the association between PDLs and embolic events, including ischaemic stroke, transient ischaemic attacks (TIAs), and systemic embolism (SE). METHODS: We conducted a systematic search of the PubMed, Web of Science, MEDLINE, and Cochrane Library databases for studies published up to September 25, 2022, to compare the rate of ischaemic stroke/TIA/SE between the PDL group and the non-PDL group after LAAC. RESULTS: Thirteen studies comprising 54,405 patients were included in the meta-analysis. The PDL group detected by transoesophageal echocardiography (TEE) had a significantly higher rate of ischaemic stroke/TIA/SE than the non-PDL group (OR: 1.20, 95% CI: 1.08-1.33, p = 0.0009). However, no difference in ischaemic stroke/TIA/SE was found between the PDL and non-PDL subgroups of the cardiac computed tomography angiography (CCTA) group (OR: 1.12, 95% CI: 0.51-2.50, p = 0.77). CCTA and TEE showed different rates of PDL detection, with the CCTA group having a higher rate of PDL detection (p < 0.0001), especially for trivial leaks. CONCLUSIONS: PDL detected by TEE increases the risk of embolic events after LAAC. However, no association was found between PDL and ischaemic stroke/TIA/SE in the CCTA group, which showed a higher rate of PDL detection than TEE, particularly for trivial leaks. In the future, CCTA may be used to explore the relationship between PDL size and ischaemic stroke/TIA/SE.

Assessment of the relationship between plasma fibrinogen-to-albumin ratio and slow coronary flow phenomenon in patients without obstructive coronary artery disease.

BACKGROUND: Prior studies have suggested that the chronic inflammatory response has an important role in the pathophysiology of slow coronary flow phenomenon (SCFP). However, data are scarce regarding the role of plasma fibrinogen-to-albumin ratio (PFAR) in patients having SCFP without obstructive coronary artery disease (CAD). In this study, we investigated the relationship between PFAR and the presence of SCFP in patients without obstructive CAD. METHODS: From January 2021 to January 2023, we consecutively recruited 1085 patients without obstructive CAD according to the diagnostic and exclusion criteria. In total, SCFP was diagnosed in 70 patients. A 1:2 age-matched case-control study was then conducted using comparators without SCFP. Ultimately, this study enrolled 70 patients with angiographically normal coronary arteries and SCFP, along with 140 comparators with angiographically normal coronary arteries and normal coronary flow. Plasma fibrinogen and albumin levels were measured, and the PFAR was then calculated for each patient. RESULTS: PFARs were significantly greater in the SCFP group than in the comparators with normal coronary flow (82.8 ± 15.4 vs 73.1 ± 19.5, p < 0.001). PFAR increased with increasing numbers of vessels affected by SCFP. Multivariate logistic regression analysis showed that PFAR was an independent predictor of SCFP (odds ratio: 1.818, p = 0.015). Receiver operating characteristic (ROC) curve analysis indicated that PFAR showed a better predictive value of SCFP than fibrinogen or albumin, although not significantly (p > 0.05). CONCLUSION: PFAR is an independent predictor of SCFP in patients without obstructive CAD. PAFR could improve the predictive value of SFCP than albumin or fibrinogen alone, but not significantly.

Ginsenoside Rg1 in neurological diseases: From bench to bedside.

Ginseng has been used in China as a superior medicinal material for thousands of years that can nourish the five internal organs, calm the mind and benefit wisdom. Due to its anti-inflammatory, antioxidant and neuroprotective activities, one of the active components of ginseng, ginsenoside Rg1, has been extensively investigated in the remedy of brain disorders, especially dementia and depression. In this review, we summarized the research progress on the action mechanisms of Rg1 ameliorating depression-like behaviors, including inhibition of hyperfunction of hypothalamic-pituitary-adrenal (HPA) axis, regulation of synaptic plasticity and gut flora. Rg1 may alleviate Alzheimer's disease in the early phase, as well as in the middle-late phases through repairing dendrite, axon and microglia- and astrocyte-related inflammations. We also proposed that Rg1 could regulate memory state (the imbalance of working and aversive memory) caused by distinct stimuli. These laboratory studies would further the clinical trials on Rg1. From the prospective of drug development, we discussed the limitations of the present investigations and proposed our ideas to increase permeability and bioavailability of Rg1. Taken together, Rg1 has the potential to treat neuropsychiatric disorders, but a future in-depth investigation of the mechanisms is still required. In addition, drug development will benefit from the clinical trials in one specific neuropsychiatric disorder.

Active Inference With Empathy Mechanism for Socially Behaved Artificial Agents in Diverse Situations.

This article proposes a method for an artificial agent to behave in a social manner. Although defining proper social behavior is difficult because it differs from situation to situation, the agent following the proposed method adaptively behaves appropriately in each situation by empathizing with the surrounding others. The proposed method is achieved by incorporating empathy into active inference. We evaluated the proposed method regarding control of autonomous mobile robots in diverse situations. From the evaluation results, an agent controlled by the proposed method could behave more adaptively socially than an agent controlled by the standard active inference in the diverse situations. In the case of two agents, the agent controlled with the proposed method behaved in a social way that reduced the other agent's travel distance by 13.7% and increased the margin between the agents by 25.8%, even though it increased the agent's travel distance by 8.2%. Also, the agent controlled with the proposed method behaved more socially when it was surrounded by altruistic others but less socially when it was surrounded by selfish others.

Synthesis of 2'-fucosyllactose from apple pomace-derived xyloglucan oligosaccharides by an α-L-fucosidase from Pedobacter sp. CAU209.

2'-Fucosyllactose (2'-FL) is known for its ability to provide various health benefits to infants, such as gut maturation, pathogen resistance, improved immunity, and nervous system development. However, the production of 2'-FL using α-L-fucosidases is hindered by the lack of low-cost natural fucosyl donors and high-efficiency α-L-fucosidases. In this work, a recombinant xyloglucanase from Rhizomucor miehei (RmXEG12A) was applied to produce xyloglucan-oligosaccharide (XyG-oligos) from apple pomace. Then, an α-L-fucosidase gene (PbFucB) was screened from the genomic DNA of Pedobacter sp. CAU209 and expressed in Escherichia coli. The capability of purified PbFucB to catalyze XyG-oligos and lactose to synthesize 2'-FL was further evaluated. The deduced amino acid sequence of PbFucB shared the highest identity (38.4%) with that of other reported α-L-fucosidases. PbFucB showed the highest activity at pH 5.5 and 35 °C. It catalyzed the hydrolysis of 4-nitrophenyl-α-L-fucopyranoside (pNP-Fuc, 20.3 U mg-1), 2'-FL (8.06 U mg-1), and XyG-oligos (0.43 U mg-1). Furthermore, PbFucB demonstrated a high enzymatic conversion rate in 2'-FL synthesis with pNP-Fuc or apple pomace-derived XyG-oligos as donors and lactose as acceptor. Under the optimized conditions, PbFucB converted 50% of pNP-Fuc or 31% of the L-fucosyl residue in XyG-oligos into 2'-FL. This work elucidated an α-L-fucosidase that mediates the fucosylation of lactose and provided an efficient enzymatic strategy to synthesize 2'-FL either from artificial pNP-Fuc or natural apple pomace-derived XyG-oligos. KEY POINTS: • Xyloglucan-oligosaccharide (XyG-oligos) was produced from apple pomace by a xyloglucanase from Rhizomucor miehei. • An α-L-fucosidase (PbFucB) from Pedobacter sp. CAU209 shared the highest identity (38.4%) with reported α-L-fucosidases. •PbFucB synthesized 2'-FL using apple pomace-derived XyG-oligos and lactose with a conversion ratio of 31%.

Stress induces p38 MAPK-mediated phosphorylation and inhibition of Drosha-dependent cell survival.

MicroRNAs (miRNAs) regulate the translational potential of their mRNA targets and control many cellular processes. The key step in canonical miRNA biogenesis is the cleavage of the primary transcripts by the nuclear RNase III enzyme Drosha. Emerging evidence suggests that the miRNA biogenic cascade is tightly controlled. However, little is known whether Drosha is regulated. Here, we show that Drosha is targeted by stress. Under stress, p38 MAPK directly phosphorylates Drosha at its N terminus. This reduces its interaction with DiGeorge syndrome critical region gene 8 and promotes its nuclear export and degradation by calpain. This regulatory mechanism mediates stress-induced inhibition of Drosha function. Reduction of Drosha sensitizes cells to stress and increases death. In contrast, increase in Drosha attenuates stress-induced death. These findings reveal a critical regulatory mechanism by which stress engages p38 MAPK pathway to destabilize Drosha and inhibit Drosha-mediated cellular survival.

Inositol hexakisphosphate primes syndapin I/PACSIN 1 activation in endocytosis.

Endocytosis is controlled by a well-orchestrated molecular machinery, where the individual players as well as their precise interactions are not fully understood. We now show that syndapin I/PACSIN 1 is expressed in pancreatic ß cells and that its knockdown abrogates ß cell endocytosis leading to disturbed plasma membrane protein homeostasis, as exemplified by an elevated density of L-type Ca2+ channels. Intriguingly, inositol hexakisphosphate (InsP6) activates casein kinase 2 (CK2) that phosphorylates syndapin I/PACSIN 1, thereby promoting interactions between syndapin I/PACSIN 1 and neural Wiskott-Aldrich syndrome protein (N-WASP) and driving ß cell endocytosis. Dominant-negative interference with endogenous syndapin I/PACSIN 1 protein complexes, by overexpression of the syndapin I/PACSIN 1 SH3 domain, decreases InsP6-stimulated endocytosis. InsP6 thus promotes syndapin I/PACSIN 1 priming by CK2-dependent phosphorylation, which endows the syndapin I/PACSIN 1 SH3 domain with the capability to interact with the endocytic machinery and thereby initiate endocytosis, as exemplified in ß cells.