A Lignin Molecular Brace Controls Precision Processing of Cell Walls Critical for Surface Integrity in Arabidopsis.

The cell wall, a defining feature of plants, provides a rigid structure critical for bonding cells together. To overcome this physical constraint, plants must process cell wall linkages during growth and development. However, little is known about the mechanism guiding cell-cell detachment and cell wall remodeling. Here, we identify two neighboring cell types in Arabidopsis that coordinate their activities to control cell wall processing, thereby ensuring precise abscission to discard organs. One cell type produces a honeycomb structure of lignin, which acts as a mechanical "brace" to localize cell wall breakdown and spatially limit abscising cells. The second cell type undergoes transdifferentiation into epidermal cells, forming protective cuticle, demonstrating de novo specification of epidermal cells, previously thought to be restricted to embryogenesis. Loss of the lignin brace leads to inadequate cuticle formation, resulting in surface barrier defects and susceptible to infection. Together, we show how plants precisely accomplish abscission.

SREBP-1c impairs ULK1 sulfhydration-mediated autophagic flux to promote hepatic steatosis in high-fat-diet-fed mice.

A metabolic imbalance between lipid synthesis and degradation can lead to hepatic lipid accumulation, a characteristic of patients with non-alcoholic fatty liver disease (NAFLD). Here, we report that high-fat-diet-induced sterol regulatory element-binding protein (SREBP)-1c, a key transcription factor that regulates lipid biosynthesis, impairs autophagic lipid catabolism via altered H2S signaling. SREBP-1c reduced cystathionine gamma-lyase (CSE) via miR-216a, which in turn decreased hepatic H2S levels and sulfhydration-dependent activation of Unc-51-like autophagy-activating kinase 1 (ULK1). Furthermore, Cys951Ser mutation of ULK1 decreased autolysosome formation and promoted hepatic lipid accumulation in mice, suggesting that the loss of ULK1 sulfhydration was directly associated with the pathogenesis of NAFLD. Moreover, silencing of CSE in SREBP-1c knockout mice increased liver triglycerides, confirming the connection between CSE, autophagy, and SREBP-1c. Overall, our results uncover a 2-fold mechanism for SREBP-1c-driven hepatic lipid accumulation through reciprocal activation and inhibition of hepatic lipid biosynthesis and degradation, respectively.

MARCH5-dependent NLRP3 ubiquitination is required for mitochondrial NLRP3-NEK7 complex formation and NLRP3 inflammasome activation.

The NLRP3 inflammasome plays a key role in responding to pathogens, and endogenous damage and mitochondria are intensively involved in inflammasome activation. The NLRP3 inflammasome forms multiprotein complexes and its sequential assembly is important for its activation. Here, we show that NLRP3 is ubiquitinated by the mitochondria-associated E3 ligase, MARCH5. Myeloid cell-specific March5 conditional knockout (March5 cKO) mice failed to secrete IL-1ß and IL-18 and exhibited an attenuated mortality rate upon LPS or Pseudomonas aeruginosa challenge. Macrophages derived from March5 cKO mice also did not produce IL-1ß and IL-18 after microbial infection. Mechanistically, MARCH5 interacts with the NACHT domain of NLRP3 and promotes K27-linked polyubiquitination on K324 and K430 residues of NLRP3. Ubiquitination-defective NLRP3 mutants on K324 and K430 residues are not able to bind to NEK7, nor form NLRP3 oligomers leading to abortive ASC speck formation and diminished IL-1ß production. Thus, MARCH5-dependent NLRP3 ubiquitination on the mitochondria is required for NLRP3-NEK7 complex formation and NLRP3 oligomerization. We propose that the E3 ligase MARCH5 is a regulator of NLRP3 inflammasome activation on the mitochondria.

PARP1-TRIM44-MRN loop dictates the response to PARP inhibitors.

PARP inhibitors (PARPi) show selective efficacy in tumors with homologous recombination repair (HRR)-defects but the activation mechanism of HRR pathway in PARPi-treated cells remains enigmatic. To unveil it, we searched for the mediator bridging PARP1 to ATM pathways by screening 211 human ubiquitin-related proteins. We discovered TRIM44 as a crucial mediator that recruits the MRN complex to damaged chromatin, independent of PARP1 activity. TRIM44 binds PARP1 and regulates the ubiquitination-PARylation balance of PARP1, which facilitates timely recruitment of the MRN complex for DSB repair. Upon exposure to PARPi, TRIM44 shifts its binding from PARP1 to the MRN complex via its ZnF UBP domain. Knockdown of TRIM44 in cells significantly enhances the sensitivity to olaparib and overcomes the resistance to olaparib induced by 53BP1 deficiency. These observations emphasize the central role of TRIM44 in tethering PARP1 to the ATM-mediated repair pathway. Suppression of TRIM44 may enhance PARPi effectiveness and broaden their use even to HR-proficient tumors.

Improvement in Health-Related Quality of Life Following Antibiotic Treatment in Nontuberculous Mycobacterial Pulmonary Disease: Initial Analysis of the NTM-KOREA Cohort.

BACKGROUND: Improving health-related quality of life (HRQOL) has emerged as a priority in the management of nontuberculous mycobacterial pulmonary disease (NTM-PD). We aimed to evaluate HRQOL and its changes after 6 months' treatment in patients with NTM-PD. METHODS: The NTM-KOREA is a nationwide prospective cohort enrolling patients initiating treatment for NTM-PD in 8 institutions across South Korea. We conducted the Quality of Life-Bronchiectasis (QOL-B) at 6-month intervals and evaluated baseline scores (higher scores indicate better quality of life) and changes after 6 months' treatment. Multivariate logistic regression was performed to identify factors associated with improvement in the QOL-B physical functioning and respiratory symptoms domains. RESULTS: Between February 2022 and August 2023, 411 patients were included in the analysis. Baseline scores (95% confidence interval [CI]) for physical functioning and respiratory symptoms were 66.7 (46.7-86.7) and 81.5 (70.4-92.6), respectively. Among 228 patients who completed the QOL-B after 6 months' treatment, improvements in physical functioning and respiratory symptoms were observed in 61 (26.8%) and 71 (31.1%) patients, respectively. A lower score (adjusted odds ratio; 95% CI) for physical functioning (0.93; 0.91-0.96) and respiratory symptoms (0.92; 0.89-0.95) at treatment initiation was associated with a greater likelihood of physical functioning and respiratory symptom improvement, respectively; achieving culture conversion was not associated with improvement in physical functioning (0.62; 0.28-1.39) or respiratory symptoms (1.30; 0.62-2.74). CONCLUSIONS: After 6 months of antibiotic treatment for NTM-PD, HRQOL improved in almost one-third, especially in patients with severe initial symptoms, regardless of culture conversion. CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov identifier: NCT03934034.

USP11 modulates mitotic progression and senescence by regulating the p53-p21 axis through MDM2 deubiquitination.

USP11 is overexpressed in colorectal cancer (CRC) and breast cancer tissues compared to normal tissues, suggesting a role in promoting cell proliferation and inhibiting cell death. In this study, we observed that depleting USP11 inhibits cell proliferation and delays cell cycle progression. This depletion leads to increased p53 protein levels due to an extended half-life, resulting in elevated p21 mRNA levels in a p53-dependent manner. The rise in p53 protein upon USP11 depletion is linked to a reduced half-life of MDM2, a known E3 ligase for p53, via enhanced polyubiquitination of MDM2. These findings indicate that USP11 might act as a deubiquitinase for MDM2, regulating the MDM2-p53-p21 axis. Additionally, USP11 depletion promotes the induction of senescent cells in a manner dependent on its deubiquitinase activity. Our findings provide insights into the physiological significance of high USP11 expression in primary tumors and its reduction in senescent cells, highlighting its potential as a therapeutic target.

The single RRM domain-containing protein SARP1 is required for establishment of the separation zone in Arabidopsis.

Abscission is the shedding of plant organs in response to developmental and environmental cues. Abscission involves cell separation between two neighboring cell types, residuum cells (RECs) and secession cells (SECs) in the floral abscission zone (AZ) in Arabidopsis thaliana. However, the regulatory mechanisms behind the spatial determination that governs cell separation are largely unknown. The class I KNOTTED-like homeobox (KNOX) transcription factor BREVIPEDICELLUS (BP) negatively regulates AZ cell size and number in Arabidopsis. To identify new players participating in abscission, we performed a genetic screen by activation tagging a weak complementation line of bp-3. We identified the mutant ebp1 (enhancer of BP1) displaying delayed floral organ abscission. The ebp1 mutant showed a concaved surface in SECs and abnormally stacked cells on the top of RECs, in contrast to the precisely separated surface in the wild-type. Molecular and histological analyses revealed that the transcriptional programming during cell differentiation in the AZ is compromised in ebp1. The SECs of ebp1 have acquired REC-like properties, including cuticle formation and superoxide production. We show that SEPARATION AFFECTING RNA-BINDING PROTEIN1 (SARP1) is upregulated in ebp1 and plays a role in the establishment of the cell separation layer during floral organ abscission in Arabidopsis.

Effectiveness of microvascular flow imaging for radiofrequency ablation in recurrent thyroid cancer: comparison with power Doppler imaging.

OBJECTIVES: To compare microvascular flow imaging (MVFI) and power Doppler ultrasonography imaging (PDUS) for detecting intratumoral vascularity in recurrent thyroid cancer both before and after radiofrequency ablation (RFA). METHODS: This retrospective study included 80 patients (age, 57 ± 12 years; 54 women) with 110 recurrent tumors who underwent RFA between January 2021 and June 2023. A total of 151 PDUS and MVFI image sets were analyzed (85 pre-RFA, 66 post-RFA). Two readers assessed vascularity on the images using a four-point scale with a 2-week interval between PDUS and MVFI to estimate inter-reader agreement. Intra-reader agreement was determined by reinterpreting images in reverse order (MVFI-PDUS) after a 1-month gap. Additionally, diagnostic performance for identifying viable tumors after RFA was assessed in 44 lesions using thyroid-protocol CT as a reference standard. RESULTS: MVFI demonstrated higher vascular grades than PDUS, both before (reader 1: 3.04 ± 1.15 vs. 1.93 ± 1.07, p < 0.001; reader 2: 3.20 ± 0.96 vs. 2.12 ± 1.07, p < 0.001) and after RFA (reader 1: 2.44 ± 1.28 vs. 1.67 ± 1.06, p < 0.001; reader 2: 2.62 ± 1.23 vs. 1.83 ± 0.99, p < 0.001). Inter-reader agreement was substantial (κ = 0.743) and intra-reader agreement was almost perfect (κ = 0.840). MVFI showed higher sensitivity (81.5%-88.9%) and accuracy (84.1%-86.4%) than PDUS (sensitivity: 51.9%, p < 0.01; accuracy: 63.6-70.5%, p < 0.04), without sacrificing specificity. CONCLUSION: MVFI was superior to PDUS for assessing intratumoral vascularity and showed good inter- and intra-reader agreement, highlighting its clinical value for assessing pre-RFA vascularity and accurately identifying post-RFA viable tumors in recurrent thyroid cancer. CLINICAL RELEVANCE STATEMENT: Microvascular flow imaging (MVFI) is superior to power-Doppler US for assessing intratumoral vascularity; therefore, MVFI can be a valuable tool for assessing vascularity before radiofrequency ablation (RFA) and for identifying viable tumors after RFA in patients with recurrent thyroid cancer. KEY POINTS: The value of microvascular flow imaging (MVFI) for evaluating intratumoral vascularity is unexplored. MVFI demonstrated higher vascular grades than power Doppler US before and after ablation. Microvascular flow imaging showed higher sensitivity and accuracy than power Doppler US without sacrificing specificity.

Nontuberculous mycobacterial pulmonary disease presenting as bronchiolitis pattern on CT without cavity or bronchiectasis.

BACKGROUND: This study aimed to investigate the radiological changes in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) having bronchiolitis patterns on computed tomography (CT). METHODS: We retrospectively reviewed the final diagnosis and radiologic changes of patients suspected of having NTM-PD without cavity or bronchiectasis on CT image, between January 1, 2005 and March 31, 2021. NTM-PD was diagnosed based on the American Thoracic Society and Infectious Diseases Society of America criteria. The initial and final CT findings (bronchiectasis, cellular bronchiolitis, cavity formation, nodules, and consolidation) were compared between patients diagnosed with and without NTM-PD. RESULTS: This study included 96 patients and 515 CT images. The median CT follow-up duration was 1510.5 (interquartile range: 862.2-3005) days. NTM-PD was recognized in 43 patients. The clinical variables were not significantly different between patients with and without NTM-PD, except for underlying chronic airway disease (P < 0.001). Nodule and consolidation were more frequently observed on the initial CT scans of patients with NTM-PD compared with those without (P < 0.05). On the final follow-up CT scan, bronchiectasis (P < 0.001), cavity (P < 0.05), nodule (P < 0.05), and consolidation (P < 0.05) were more frequently observed in patients with NTM-PD. Among the 43 patients with NTM-PD, 30 showed a radiological progression on CT, with bronchiectasis (n = 22) being the most common finding. The incidence of bronchiectasis increased over time. CONCLUSION: The bronchiolitis pattern on CT images of patients with NTM-PD showed frequent radiological progression during the follow-up period.

Understanding the effects of Haemophilus influenzae colonization on bronchiectasis: a retrospective cohort study.

BACKGROUND: Bacterial colonization is an essential aspect of bronchiectasis. Although Haemophilus influenzae is a frequent colonizer in some regions, its clinical impacts are poorly understood. This study aimed to elucidate the impact of H. influenzae colonization in patients with bronchiectasis. METHODS: This retrospective study screened adult patients diagnosed with bronchiectasis at a tertiary referral center between April 1, 2003, and May 16, 2021, in South Korea. Propensity score matching was used to match patients with and without H. influenzae colonization. We assessed the severity of bronchiectasis as per the bronchiectasis severity index, the incidence of exacerbation, differences in lung function, and all-cause mortality. RESULTS: Out of the 4,453 patients with bronchiectasis, 79 (1.8%) were colonized by H. influenzae. After 1:2 propensity score matching, 78 and 154 patients were selected from the H. influenzae colonizer and non-colonizer groups, respectively. Although there were no significant differences between the groups regarding baseline demographics, patients colonized with H. influenzae had a higher bronchiectasis severity index (median 6 [interquartile range 4-8] vs. 4 [2-7], p = 0.002), associated with extensive radiographic involvement (52.2% vs. 37.2%, p = 0.045) and mild exacerbation without hospitalization (adjusted incidence rate ratio 0.15; 95% confidence interval 0.12-0.24). Lung function and mortality rates did not reveal significant differences, regardless of H. influenzae colonization. CONCLUSION: H. influenzae colonization in bronchiectasis was associated with more severe disease and greater incidence of mild exacerbation, but not lung function and mortality. Attention should be paid to patients with bronchiectasis with H. influenzae colonization.