Differential spatial distribution of miR165/6 determines variability in plant root anatomy

A clear example of interspecific variation is the number of root cortical layers in plants. The genetic mechanisms underlying this variability are poorly understood, partly due to the lack of a convenient model. Here, we demonstrate that Cardamine hirsuta, unlike Arabidopsis thaliana, has two cortical layers that are patterned during late embryogenesis. We show that a miR165/6-dependent distribution of the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII) transcription factor PHABULOSA (PHB) controls this pattern. Our findings reveal that interspecies variation in miRNA distribution can determine differences in anatomy in plants

A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root

In both animals and plants, development involves anatomical modifications. In the root of Arabidopsis thaliana, maturation of the ground tissue (GT)—a tissue comprising all cells between epidermal and vascular ones—is a paradigmatic example of these modifications, as it generates an additional tissue layer, the middle cortex (MC).1, 2, 3, 4 In early post-embryonic phases, the Arabidopsis root GT is composed of one layer of endodermis and one of cortex. A second cortex layer, the MC, is generated by asymmetric cell divisions in about 80% of Arabidopsis primary roots, in a time window spanning from 7 to 14 days post-germination (dpg). The cell cycle regulator CYCLIN D6;1 (CYCD6;1) plays a central role in this process, as its accumulation in the endodermis triggers the formation of MC.5 The phytohormone gibberellin (GA) is a key regulator of the timing of MC formation, as alterations in its signaling and homeostasis result in precocious endodermal asymmetric cell divisions.3,6,7 However, little is known on how GAs are regulated during GT maturation. Here, we show that the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII) transcription factor PHABULOSA (PHB) is a master regulator of MC formation, controlling the accumulation of CYCD6;1 in the endodermis in a cell non-autonomous manner. We show that PHB activates the GA catabolic gene GIBBERELLIN 2 OXIDASE 2 (GA2ox2) in the vascular tissue, thus regulating the stability of the DELLA protein GIBBERELLIN INSENSITIVE (GAI)—a GA signaling repressor—in the root and, hence, CYCD6;1 expression in the endodermis

Cytokinin-Dependent Control of <i>GH3</i> Group II Family Genes in the <i>Arabidopsis</i> Root

The Arabidopsis root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. The hormone cytokinin shapes this gradient by positioning an auxin minimum in the last meristematic cells. This auxin minimum triggers a cell developmental switch necessary to start the differentiation program, thus, regulating the root meristem size. To position the auxin minimum, cytokinin promotes the expression of the IAA-amido synthase group II gene GH3.17, which conjugates auxin with amino acids, in the most external layer of the root, the lateral root cap tissue. Since additional GH3 genes are expressed in the root, we questioned whether cytokinin to position the auxin minimum also operates via different GH3 genes. Here, we show that cytokinin regulates meristem size by activating the expression of GH3.5 and GH3.6 genes, in addition to GH3.17. Thus, cytokinin activity provides a robust control of auxin activity in the entire organ necessary to regulate root growth

The mutual inhibition between PLETHORAs and ARABIDOPSIS RESPONSE REGULATORs controls root zonation

During organogenesis a key step towards the development of a functional organ is the separation of cells in specific domains with different activities. Mutual inhibition of gene expression has been shown to be sufficient to establish and maintain these domains during organogenesis of several multicellular organisms. Here we show that the mutual inhibition between the PLTs and the ARRs transcription factors is sufficient to separate cell division and cell differentiation during root organogenesis. In particular, we show that ARR1 suppresses PLTs activities and that PLTs suppress ARR1 and ARR12 by targeting their protein for degradation via the KMD2 F-box protein. These findings reveal new important aspects of the complex process of root zonation and development

microRNA165 and 166 modulate response of the Arabidopsis root apical meristem to salt stress

Abstract In plants, developmental plasticity allows for the modulation of organ growth in response to environmental cues. Being in contact with soil, roots are the first organ that responds to various types of soil abiotic stress such as high salt concentration. In the root, developmental plasticity relies on changes in the activity of the apical meristem, the region at the tip of the root where a set of self-renewing undifferentiated stem cells sustain growth. Here, we show that salt stress promotes differentiation of root meristem cells via reducing the dosage of the microRNAs miR165 and 166. By means of genetic, molecular and computational analysis, we show that the levels of miR165 and 166 respond to high salt concentration, and that miR165 and 166-dependent PHABULOSA (PHB) modulation is central to the response of root growth to this stress. Specifically, we show that salt-dependent reduction of miR165 and 166 causes a rapid increase in PHB expression and, hence, production of the root meristem pro-differentiation hormone cytokinin. Our data provide direct evidence for how the miRNA-dependent modulation of transcription factor dosage mediates plastic development in plants

Alpha-synuclein seeds in olfactory mucosa and cerebrospinal fluid of patients with dementia with Lewy bodies

In patients with suspected dementia with Lewy bodies, the detection of the disease-associated alpha-synuclein in easily accessible tissues amenable to be collected using minimally invasive procedures remains a major diagnostic challenge. This approach has the potential to take advantage of modern molecular assays for the diagnosis of alpha-synucleinopathy and, in turn, to optimize the recruitment and selection of patients in clinical trials, using drugs directed at counteracting alpha-synuclein aggregation. In this study, we explored the diagnostic accuracy of alpha-synuclein real-time quaking-induced conversion assay by testing olfactory mucosa and CSF in patients with a clinical diagnosis of probable (n=32) or prodromal (n=5) dementia with Lewy bodies or mixed degenerative dementia (dementia with Lewy bodies/Alzheimer's disease) (n=6). Thirty-eight patients with non-alpha-synuclein-related neurodegenerative and non-neurodegenerative disorders, including Alzheimer's disease (n=10), sporadic Creutzfeldt-Jakob disease (n=10), progressive supranuclear palsy (n=8), corticobasal syndrome (n=1), fronto-temporal dementia (n=3) and other neurological conditions (n=6) were also included, as controls. All 81 patients underwent olfactory swabbing while CSF was obtained in 48 participants. At the initial blinded screening of olfactory mucosa samples, 38 out of 81 resulted positive while CSF was positive in 19 samples out of 48 analysed. After unblinding of the results, 27 positive olfactory mucosa were assigned to patients with probable dementia with Lewy bodies, five with prodromal dementia with Lewy bodies and three to patients with mixed dementia, as opposed to three out 38 controls. Corresponding results of CSF testing disclosed 10 out 10 positive samples in patients with probable dementia with Lewy bodies and six out of six with mixed dementia, in addition to three out of 32 for controls. The accuracy among results of real-time quaking-induced conversion assays and clinical diagnoses was 86.4% in the case of olfactory mucosa and 93.8% for CSF. For the first time, we showed that alpha-synuclein real-time quaking-induced conversion assay detects alpha-synuclein aggregates in olfactory mucosa of patients with dementia with Lewy bodies and with mixed dementia. Additionally, we provided preliminary evidence that the combined testing of olfactory mucosa and CSF raised the concordance with clinical diagnosis potentially to 100%. Our results suggest that nasal swabbing might be considered as a first-line screening procedure in patients with a diagnosis of suspected dementia with Lewy bodies followed by CSF analysis, as a confirmatory test, when the result in the olfactory mucosa is incongruent with the initial clinical diagnosis

Statins, ACE/ARBs drug use, and risk of pneumonia in hospitalized older patients: a retrospective cohort study

: The aims of this study is to evaluate the association between angiotensin-converting enzyme inhibitor (ACE-I), angiotensin II receptor blocker (ARBs) and/or statin use with the risk of pneumonia, as well as and with in-hospital and short-term outpatient mortality in hospitalized older patients with pneumonia. Patients aged 65 years or older hospitalized in internal medicine and/or geriatric wards throughout Italy and enrolled in the REPOSI (REgistro Politerapuie SIMI-Società Italiana di Medicina Interna) register from 2010 to 2019 were screened to assess the diagnosis of pneumonia and classified on whether or not they were prescribed with at least one drug among ACE-I, ARBs, and/or statins. Further study outcomes were mortality during hospital stay and at 3 months after hospital discharge. Among 5717 cases included (of whom 18.0% with pneumonia), 2915 (51.0%) were prescribed at least one drug among ACE-I, ARBs, and statins. An inverse association was found between treatment with ACE-I or ARBs and pneumonia (OR = 0.79, 95% CI 0.65-0.95). A higher effect was found among patients treated with ACE-I or ARBs in combination with statins (OR = 0.67, 95% CI 0.52-0.85). This study confirmed in the real-world setting that these largely used medications may reduce the risk of pneumonia in older people, who chronically take them for cardiovascular conditions

Antihypertensive treatment changes and related clinical outcomes in older hospitalized patients

Background: Hypertension management in older patients represents a challenge, particularly when hospitalized. Objective: The objective of this study is to investigate the determinants and related outcomes of antihypertensive drug prescription in a cohort of older hospitalized patients. Methods: A total of 5671 patients from REPOSI (a prospective multicentre observational register of older Italian in-patients from internal medicine or geriatric wards) were considered; 4377 (77.2%) were hypertensive. Minimum treatment (MT) for hypertension was defined according to the 2018 ESC guidelines [an angiotensin-converting-enzyme-inhibitor (ACE-I) or an angiotensin-receptor-blocker (ARB) with a calcium-channel-blocker (CCB) and/or a thiazide diuretic; if &gt;80 years old, an ACE-I or ARB or CCB or thiazide diuretic]. Determinants of MT discontinuation at discharge were assessed. Study outcomes were any cause rehospitalization/all cause death, all-cause death, cardiovascular (CV) hospitalization/death, CV death, non-CV death, evaluated according to the presence of MT at discharge. Results: Hypertensive patients were older than normotensives, with a more impaired functional status, higher burden of comorbidity and polypharmacy. A total of 2233 patients were on MT at admission, 1766 were on MT at discharge. Discontinuation of MT was associated with the presence of comorbidities (lower odds for diabetes, higher odds for chronic kidney disease and dementia). An adjusted multivariable logistic regression analysis showed that MT for hypertension at discharge was associated with lower risk of all-cause death, all-cause death/hospitalization, CV death, CV death/hospitalization and non-CV death. Conclusions: Guidelines-suggested MT for hypertension at discharge is associated with a lower risk of adverse clinical outcomes. Nevertheless, changes in antihypertensive treatment still occur in a significant proportion of older hospitalized patients

Understanding Factors Associated With Psychomotor Subtypes of Delirium in Older Inpatients With Dementia

Objectives: Few studies have analyzed factors associated with delirium subtypes. In this study, we investigate factors associated with subtypes of delirium only in patients with dementia to provide insights on the possible prevention and treatments. Design: This is a cross-sectional study nested in the \u201cDelirium Day\u201d study, a nationwide Italian point-prevalence study. Setting and Participants: Older patients admitted to 205 acute and 92 rehabilitation hospital wards. Measures: Delirium was evaluated with the 4-AT and the motor subtypes with the Delirium Motor Subtype Scale. Dementia was defined by the presence of a documented diagnosis in the medical records and/or prescription of acetylcholinesterase inhibitors or memantine prior to admission. Results: Of the 1057 patients with dementia, 35% had delirium, with 25.6% hyperactive, 33.1% hypoactive, 34.5% mixed, and 6.7% nonmotor subtype. There were higher odds of having venous catheters in the hypoactive (OR 1.82, 95% CI 1.18-2.81) and mixed type of delirium (OR 2.23, CI 1.43-3.46), whereas higher odds of urinary catheters in the hypoactive (OR 2.91, CI 1.92-4.39), hyperactive (OR 1.99, CI 1.23-3.21), and mixed types of delirium (OR 2.05, CI 1.36-3.07). We found higher odds of antipsychotics both in the hyperactive (OR 2.87, CI 1.81-4.54) and mixed subtype (OR 1.84, CI 1.24-2.75), whereas higher odds of antibiotics was present only in the mixed subtype (OR 1.91, CI 1.26-2.87). Conclusions and Implications: In patients with dementia, the mixed delirium subtype is the most prevalent followed by the hypoactive, hyperactive, and nonmotor subtype. Motor subtypes of delirium may be triggered by clinical factors, including the use of venous and urinary catheters, and the use of antipsychotics. Future studies are necessary to provide further insights on the possible pathophysiology of delirium in patients with dementia and to address the optimization of the management of potential risk factors