ALTERED MERISTEM PROGRAM1 sustains cellular differentiation by limiting HD-ZIP III transcription factor gene expression.

Plants show remarkable developmental and regenerative plasticity through the sustained activity of stem cells in meristems. Under certain conditions, pluripotency can even be re-established in cells that have already entered differentiation. Mutation of the putative carboxypeptidase ALTERED MERISTEM PROGRAM1 (AMP1) in Arabidopsis (Arabidopsis thaliana) causes a set of hypertrophic phenotypes, indicating a defect in the suppression of pluripotency. A role of AMP1 in the miRNA-mediated inhibition of translation has previously been reported, however, how this activity is related to its developmental functions is unclear. Here we examined the functional interaction between AMP1 and the Class III homeodomain-leucine zipper (HD-ZIP III) transcription factors, which are miRNA-controlled determinants of shoot meristem specification. We found that the HD-ZIP III transcriptional output is enhanced in the amp1 mutant and that plant lines with increased HD-ZIP III activity not only developed amp1 mutant-like phenotypes but also showed a synergistic genetic interaction with the mutant. Conversely, the reduction of HD-ZIP III function suppressed the shoot hypertrophy defects of the amp1 mutant. We further provide evidence that the expression domains of HD-ZIP III family members are expanded in the amp1 mutant and that this misexpression occurs at the transcriptional level and does not involve the function of miRNA165/166. Finally, amp1 mutant-specific phenotypes cannot be mimicked by a general inhibition of miRNA function in the AMP1 expression domain. These findings lead us to a model in which AMP1 restricts cellular pluripotency upstream of HD-ZIP III proteins and this control appears to be not directly mediated by the canonical miRNA pathway.

Remnant cholesterol trajectory and subclinical arteriosclerosis: a 10-year longitudinal study of Chinese adults.

We aimed to identify different trajectories of remnant cholesterol (RC) and investigate the association of RC trajectories with vascular endothelial function and atherosclerosis progression in a longitudinal cohort of the Chinese population. A total of 521 participants were included in the flow-mediated vasodilation (FMD) subcohort study, and 7775 participants were included in the brachial-ankle pulse wave velocity (baPWV) subcohort study. All participants had ≥ 3 medical examinations during the 10-year follow-up period. In the FMD subcohort study, three distinct RC trajectories were identified according to the RC range and changing pattern over time: "low" (57.58%), "moderate" (30.90%) and "high" (11.52%). The proportion of the three groups with vascular endothelial dysfunction (FMD < 7.0%) was 20.00%, 39.75% and 60.00% respectively. Taking the low group as a reference, participants in the moderate and high groups had over 1.88 and 2.94 times the odds of vascular endothelial dysfunction (P = 0.048). In the baPWV subcohort study, three distinct RC trajectories were also identified: "low" (54.29%), "moderate" (38.97%) and "high" (6.74%). The proportion of the three groups with atherosclerosis (baPWV > 1400 cm/s) was 38.79%, 51.26% and 59.01% respectively. Taking the low group as a reference, participants in the moderate and high groups had over 1.46 and 2.16 times the odds of atherosclerosis (P < 0.001). The findings indicated that distinct RC trajectories are significantly associated with vascular endothelial function and atherosclerosis. Regular monitoring to identify persistent increases in RC may be more helpful in identifying individuals with a high risk of cardiovascular disease.

Arterial stiffness progression in metabolic dysfunction-associated fatty liver disease subtypes: A prospective cohort study.

BACKGROUND AND AIMS: We aimed to investigate the correlation and to explore which MAFLD subtypes have the greatest influence on progression of arterial stiffness risk. METHODS AND RESULTS: Using data from a health examination-based cohort, a total of 12,129 participants who underwent two repeated health examinations that included brachial-ankle pulse wave velocity (baPWV) from 2012 to 2020 were enrolled. Participants were separated into non-MAFLD, overweight/obese (OW-MAFLD), lean/normal weight (lean-MAFLD) and diabetes (DM-MAFLD) groups. Among the participants with a median follow-up of 2.17 years, 4511 (37.2%) participants had MAFLD at baseline, among which 3954 (87.7%), 123 (2.7%), and 434 (9.6%) were OW-, lean- and DM-MAFLD, respectively. Analyses using linear regression models confirmed that compared with the non-MAFLD group, the elevated baPWV change rates (cm/s/year) were 12.87 (8.81-16.94), 25.33 (7.84-42.83) and 38.49 (27.88-49.10) in OW, lean and DM-MAFLD, respectively, while the increased change proportions (%) were 1.53 (1.10-1.95), 3.56 (1.72-5.40) and 3.94 (2.82-5.05), respectively. Similar patterns were observed when these two baPWV parameters were transformed in the form of the greatest increase using Cox proportional hazards model analyses. Furthermore, the risk of arterial stiffness progression across MAFLD subtypes presented a significant, gradient, inverse relationship in the order of DM-, lean-, OW with metabolic abnormalities (MA)-, and OW without MA-MAFLD. CONCLUSION: MAFLD, especially DM-MAFLD and lean-MAFLD, was significantly associated with arterial stiffness progression, providing evidence that stratification screening and surveillance strategies for CVD risk have important clinical implications.

Not only baseline but cumulative exposure of remnant cholesterol predicts the development of nonalcoholic fatty liver disease: a cohort study.

BACKGROUND AND AIM: Remnant cholesterol (remnant-C) mediates the progression of major adverse cardiovascular events. It is unclear whether remnant-C, and particularly cumulative exposure to remnant-C, is associated with nonalcoholic fatty liver disease (NAFLD). This study aimed to explore whether remnant-C, not only baseline but cumulative exposure, can be used to independently evaluate the risk of NAFLD. METHODS: This study included 1 cohort totaling 21,958 subjects without NAFLD at baseline who underwent at least 2 repeated health checkups and 1 sub-cohort totaling 2,649 subjects restricted to those individuals with at least 4 examinations and no history of NAFLD until Exam 3. Cumulative remnant-C was calculated as a timeweighted model for each examination multiplied by the time between the 2 examinations divided the whole duration. Cox regression models were performed to estimate the association between baseline and cumulative exposure to remnant-C and incident NAFLD. RESULTS: After multivariable adjustment, compared with the quintile 1 of baseline remnant-C, individuals with higher quintiles demonstrated significantly higher risks for NAFLD (hazard ratio [HR] 1.48, 95%CI 1.31-1.67 for quintile 2; HR 2.07, 95%CI 1.85-2.33 for quintile 3; HR 2.55, 95%CI 2.27-2.88 for quintile 4). Similarly, high cumulative remnant-C quintiles were significantly associated with higher risks for NAFLD (HR 3.43, 95%CI 1.95-6.05 for quintile 2; HR 4.25, 95%CI 2.44-7.40 for quintile 3; HR 6.29, 95%CI 3.59-10.99 for quintile 4), compared with the quintile 1. CONCLUSION: Elevated levels of baseline and cumulative remnant-C were independently associated with incident NAFLD. Monitoring immediate levels and longitudinal trends of remnant-C may need to be emphasized in adults as part of NAFLD prevention strategy.

Association of High-Sensitivity C-Reactive Protein and Lipoprotein-Associated Phospholipase A2 with Metabolically Unhealthy Phenotype: A Cross Sectional Study.

Objective: Whether the combination of high-sensitivity C-reactive protein (hs-CRP) and Lipoprotein-associated Phospholipase A2 (Lp-PLA2) was an independent risk factor for metabolic unhealthy is unknown. This study aimed to evaluate the association between combining hs-CRP and Lp-PLA2 and metabolic unhealthy. Methods: A total of 3198 participants who underwent routine health check-up examinations. The participants completed inflammation indicators (hs-CRP and Lp-PLA2) examination and physical assessments. Four phenotypes were determined according to obesity and metabolic health status. Meanwhile, the participants were divided into four groups according to the level of hs-CRP and Lp-PLA2. The cross-sectional association between hs-CRP, Lp-PLA2 and metabolic unhealthy was tested by logistic regression analysis. Results: About 30.48%, 17.35%, 17.32% and 34.83% had MHNO, MUNO, MHO, and MUO, respectively. The combination of the hs-CRP and Lp-PLA2 levels was significantly correlated with metabolic unhealthy in non-obese subjects. However, in obese subjects, only hs-CRP level was significantly correlated with metabolic unhealthy. Conclusion: The hs-CRP and Lp-PLA2 together were significantly associated with metabolic unhealthy in non-obese subjects. hs-CRP level was significantly correlated with metabolic unhealthy in obese subjects.

Relationship between sedentary behavior and endothelial dysfunction in a cross-sectional study in China.

Sedentary behavior is a risk factor for several diseases, and previous studies have mostly reported the effects of acute sedentary behavior on vascular endothelial function. Data on the relationship between sedentary lifestyle habits and vascular function in large sample populations are lacking. Therefore, the aim of this study was to assess the correlation between self-reported sedentary behavior and peripheral vascular function in a check-up population from real-world data. Methods: We recruited 13,220 participants from two health management centers of general tertiary hospitals located in northern and southern China between 2017 and 2021. All participants had undergone both questionnaires and brachial artery flow-mediated dilation (FMD) measurements. Results: In total, 3,205 participants with FMD ≤ 5.0% were identified to have endothelial dysfunction. In a multivariable regression model including lifestyle habits such as sedentary behavior and cardiovascular risk factors, taking leisure sedentary time <2 h/day as a reference, the risk of vascular endothelial dysfunction gradually increased with time: 2-4 h/day (OR = 1.182, 95% CI: 1.058-1.321, P = 0.003), 4-6 h/day (OR = 1.248, 95% CI: 1.100-1.414, P = 0.001) and >6 h/day (OR = 1.618, 95% CI: 1.403-1.866, P < 0.001). Conclusion: Longer leisure sedentary time is associated with a higher prevalence of vascular endothelial dysfunction. These findings suggest that leisure sedentary behavior is a risk factor for the occurrence of vascular endothelial dysfunction in the Chinese check-up population.

The Association of Remnant Cholesterol with Endothelial Dysfunction and Subclinical Atherosclerosis in a Check-Up Population in China.

AIM: Vascular endothelial function and atherosclerosis are known to be important risk factors for cardiovascular disease. However, it remains unknown whether remnant cholesterol (RC) correlates with vascular endothelial function and atherosclerosis as represented by flow-mediated vasodilation (FMD) and brachial-ankle pulse wave velocity (baPWV). Therefore, in this study, we aimed to investigate this in the general population. METHODS: In this study, we examined 13,237 subjects who have undergone blood lipid, FMD, and baPWV measurements. Participants were divided into four groups based on RC quartiles. Multivariable linear regression models were used to calculate odds ratios for FMD and baPWV according to the RC levels. RESULTS: A significant negative relationship was found between RC and FMD (ß=-0.14, p=0.014), whereas RC was positively associated with baPWV (ß=21.42, p＜0.001), especially in the male and without chronic disease medication populations. The population was divided into three groups according to their lipids: dyslipidemia group, nondyslipidemia but RC increased group (RC ＞0.78 mmol/L), and nondyslipidemia and RC normal group (RC ≤ 0.78 mmol/L). The FMD of the three groups was 7.09%±3.36%, 7.39%±3.38%, and 7.57%±3.54%, respectively. The baPWV of the three groups was 1445.26±261.56 cm/s, 1425.04±265.24 cm/s, and 1382.73±267.75 cm/s. Significant differences were noted between the groups. CONCLUSIONS: The findings indicated that a higher RC was an independent predictive factor for participants with endothelial function and atherosclerosis. It is important to use RC as a risk management indicator of vascular function, especially for those with normal conventional lipid parameters but increased RC.

A novel chemical inhibitor of polar auxin transport promotes shoot regeneration by local enhancement of HD-ZIP III transcription.

De novo shoot organogenesis is a prerequisite for numerous applications in plant research and breeding but is often a limiting factor, for example, in genome editing approaches. Class III homeodomain-leucine zipper (HD-ZIP III) transcription factors have been characterized as crucial regulators of shoot specification, however up-stream components controlling their activity during shoot regeneration are only partially identified. In a chemical genetic screen, we isolated ZIC2, a novel activator of HD-ZIP III activity. Using molecular, physiological and hormone transport analyses in Arabidopsis and sunflower (Helianthus annuus), we examined the molecular mechanism by which the drug promotes HD-ZIP III expression. ZIC2-dependent upregulation of HD-ZIP III transcription promotes shoot regeneration in Arabidopsis and is accompanied by the induction of shoot specifying factors WUS and RAP2.6L and a subset of cytokinin biosynthesis enzymes. ZIC2's effect on HD-ZIP III expression and regeneration is based on its ability to limit polar auxin transport. We further provide evidence that chemical modulation of auxin efflux can enhance de novo shoot formation in the regeneration recalcitrant species sunflower. Activation of HD-ZIP III transcription during shoot regeneration depends on the local distribution of auxin and chemical modulation of auxin transport can be used to overcome poor shoot organogenesis in tissue culture.

AMP1 and CYP78A5/7 act through a common pathway to govern cell fate maintenance in Arabidopsis thaliana.

Higher plants can continuously form new organs by the sustained activity of pluripotent stem cells. These stem cells are embedded in meristems, where they produce descendants, which undergo cell proliferation and differentiation programs in a spatiotemporally-controlled manner. Under certain conditions, pluripotency can be reestablished in descending cells and this reversion in cell fate appears to be actively suppressed by the existing stem cell pool. Mutation of the putative carboxypeptidase ALTERED MERISTEM PROGRAM1 (AMP1) in Arabidopsis causes defects in the suppression of pluripotency in cells normally programmed for differentiation, giving rise to unique hypertrophic phenotypes during embryogenesis as well as in the shoot apical meristem. A role of AMP1 in the miRNA-dependent control of translation has recently been established, however, how this activity is connected to its developmental functions is not resolved. Here we identify members of the cytochrome P450 clade CYP78A to act in parallel with AMP1 to control cell fate in Arabidopsis. Mutation of CYP78A5 and its close homolog CYP78A7 in a cyp78a5,7 double mutant caused suspensor-to-embryo conversion and ectopic stem cell pool formation in the shoot meristem, phenotypes characteristic for amp1. The tissues affected in the mutants showed pronounced expression levels of AMP1 and CYP78A5 in wild type. A comparison of mutant transcriptomic responses revealed an intriguing degree of overlap and highlighted alterations in protein lipidation processes. Moreover, we also found elevated protein levels of selected miRNA targets in cyp78a5,7. Based on comprehensive genetic interaction studies we propose a model in which both enzyme classes act on a common downstream process to sustain cell fate decisions in the early embryo and the shoot apical meristem.

Salt intake assessed by spot urine on physical examination in Hunan, China.

BACKGROUND AND OBJECTIVES: Excessive salt intake is a major public health problem in several countries, especially in China. However, few people are aware of their salt intake. The purpose of this study is to carry out salt intake test in routine physical examination, and to explore the salt intake of different populations and their correlation with diet. METHODS AND STUDY DESIGN: Spot urine sample was collected to test urinary sodium and creatinine excretions for each participant recruited from physical examinations at the Third Xiangya Hospital. The Tanaka formula was used to estimate 24-h urinary sodium excretion, which reflects salt intake. In addition to physical and laboratory examination, information including personal details, health-related habits, and selfreported disease histories was obtained from the National Physical Examination Questionnaire. RESULTS: In total, 26,406 people completed the salt intake evaluation. After data cleansing, the average salt intake was 8.39±1.80 g/d. Male, middle-aged, overweight and obese, hypertensive, and dyslipidaemic populations, as well as those with non-cardiovascular diseases were more likely to have excessive salt intake. Dietary sources had an effect on salt intake. Salt intake was lower in those who consumed more milk and fruit (both p and p trend<0.01) but was higher in those who consumed more lean meat (both p and p trend<0.05), fatty meat (both p and p trend<0.01) and animal organs (both p and p trend<0.01). CONCLUSIONS: The salt intake in this population far surpasses the recommended amount. We strongly recommend salt intake assessment as routine test into physical examination center.

ALTERED MERISTEM PROGRAM1 Restricts Shoot Meristem Proliferation and Regeneration by Limiting HD-ZIP III-Mediated Expression of RAP2.6L.

Plants show an indeterminate mode of growth by the activity of organ forming stem cell niches in apically positioned meristems. The correct formation and activity of these meristems are a prerequisite for their adaptive development and also allow the maintenance of organogenesis under adverse circumstances such as wounding. Mutation of the putative Arabidopsis (Arabidopsis thaliana) Glu carboxypeptidase ALTERED MERISTEM PROGRAM1 (AMP1) results in Arabidopsis plants with enlarged shoot apical meristems, supernumerary stem cell pools, and higher leaf formation rate. AMP1 deficiency also causes exaggerated de novo formation of shoot meristems. The activity of AMP1 has been implicated in the control of microRNA (miRNA)-dependent translation; however, it is not known how this function contributes to the shoot meristem defects. Here, we show that the transcription factor RAP2.6L is upregulated in the Arabidopsis amp1 mutant. Overexpression of RAP2.6L in the wild type causes amp1 mutant-related phenotypic and molecular defects, including enhanced shoot regeneration in tissue culture. Conversely, inhibition of RAP2.6L in the amp1 mutant suppresses stem cell hypertrophy and the regenerative capacity. We further provide evidence that RAP2.6L is under direct transcriptional control of miRNA-regulated class III homeodomain-Leu zipper (HD-ZIP III) proteins, key regulators of shoot meristem development, which overaccumulate in the amp1 mutant. Our results reveal a transcription factor module acting downstream of AMP1 in the control of shoot stem cell niche patterning. By positioning the HD-ZIP III/RAP2.6L module downstream of AMP1 function, we provide a mechanistic link between the role of AMP1 in miRNA-mediated translational repression and shoot stem cell specification.

The Small Molecule Hyperphyllin Enhances Leaf Formation Rate and Mimics Shoot Meristem Integrity Defects Associated with AMP1 Deficiency.

ALTERED MERISTEM PROGRAM1 (AMP1) is a member of the M28 family of carboxypeptidases with a pivotal role in plant development and stress adaptation. Its most prominent mutant defect is a unique hypertrophic shoot phenotype combining a strongly increased organ formation rate with enhanced meristem size and the formation of ectopic meristem poles. However, so far the role of AMP1 in shoot development could not be assigned to a specific molecular pathway nor is its biochemical function resolved. In this work we evaluated the level of functional conservation between AMP1 and its human homolog HsGCPII, a tumor marker of medical interest. We show that HsGCPII cannot substitute AMP1 in planta and that an HsGCPII-specific inhibitor does not evoke amp1-specific phenotypes. We used a chemical genetic approach to identify the drug hyperphyllin (HP), which specifically mimics the shoot defects of amp1, including plastochron reduction and enlargement and multiplication of the shoot meristem. We assessed the structural requirements of HP activity and excluded that it is a cytokinin analog. HP-treated wild-type plants showed amp1-related tissue-specific changes of various marker genes and a significant transcriptomic overlap with the mutant. HP was ineffective in amp1 and elevated the protein levels of PHAVOLUTA, consistent with the postulated role of AMP1 in miRNA-controlled translation, further supporting an AMP1-related mode of action. Our work suggests that plant and animal members of the M28 family of proteases adopted unrelated functions. With HP we provide a tool to characterize the plant-specific functions of this important class of proteins.

ENO2 activity is required for the development and reproductive success of plants, and is feedback-repressed by AtMBP-1.

Enolases are key glycolytic enzymes that are highly conserved in prokaryotic and eukaryotic organisms, and are among the most abundant cytosolic proteins. In this study we provide evidence that activity of the enolase ENO2 is essential for the growth and development of plants. We show that Arabidopsis plants with compromised ENO2 function, which were generated by mutating the LOS2/ENO2 locus, have severe cellular defects, including reduced cell size and defective cell differentiation with restricted lignification. At the tissue and organ level LOS2/ENO2-deficient plants are characterized by the reduced growth of shoots and roots, altered vascular development and defective secondary growth of stems, impaired floral organogenesis and defective male gametophyte function, resulting in embryo lethality as well as delayed senescence. These phenotypes correlate with reduced lignin and increased salicylic acid contents as well as altered fatty acid and soluble sugar composition. In addition to an enolase the LOS2/ENO2 locus encodes the transcription factor AtMBP-1, and here we reveal that this bifunctionality serves to maintain the homeostasis of ENO2 activity. In summary, we show that in plants enolase function is required for the formation of chorismate-dependent secondary metabolites, and that this activity is feedback-inhibited by AtMBP-1 to enable the normal development and reproductive success of plants.