Unique functions for Notch4 in murine embryonic lymphangiogenesis

Publisher Copyright: © 2021, The Author(s).In mice, embryonic dermal lymphatic development is well understood and used to study gene functions in lymphangiogenesis. Notch signaling is an evolutionarily conserved pathway that modulates cell fate decisions, which has been shown to both inhibit and promote dermal lymphangiogenesis. Here, we demonstrate distinct roles for Notch4 signaling versus canonical Notch signaling in embryonic dermal lymphangiogenesis. Actively growing embryonic dermal lymphatics expressed NOTCH1, NOTCH4, and DLL4 which correlated with Notch activity. In lymphatic endothelial cells (LECs), DLL4 activation of Notch induced a subset of Notch effectors and lymphatic genes, which were distinctly regulated by Notch1 and Notch4 activation. Treatment of LECs with VEGF-A or VEGF-C upregulated Dll4 transcripts and differentially and temporally regulated the expression of Notch1 and Hes/Hey genes. Mice nullizygous for Notch4 had an increase in the closure of the lymphangiogenic fronts which correlated with reduced vessel caliber in the maturing lymphatic plexus at E14.5 and reduced branching at E16.5. Activation of Notch4 suppressed LEC migration in a wounding assay significantly more than Notch1, suggesting a dominant role for Notch4 in regulating LEC migration. Unlike Notch4 nulls, inhibition of canonical Notch signaling by expressing a dominant negative form of MAML1 (DNMAML) in Prox1+ LECs led to increased lymphatic density consistent with an increase in LEC proliferation, described for the loss of LEC Notch1. Moreover, loss of Notch4 did not affect LEC canonical Notch signaling. Thus, we propose that Notch4 signaling and canonical Notch signaling have distinct functions in the coordination of embryonic dermal lymphangiogenesis.Peer reviewe

Deletion analysis of spinal muscular atrophy in southern Indian population

Background: Proximal spinal muscular atrophy (SMA) is a genetically heterogeneous disease with paresis and muscle atrophy due to loss of anterior horn cell function. The survival of motor neuron gene (SMN) and neuronal apoptosis inhibitory protein (NAIP) play a primary role. Both the gene homologues exist as inverted duplications on Chromosome 5q. The telomeric/functional (SMN1) and the centromeric (SMN2) copies differ from each other in eight nucleotides. The C→T transition (at Codon 280) within Exon 7 of SMN2 causes disruption of an exonic splicing enhancer (ESE) and/or creates an exonic splicing silencer (ESS) leading to abnormal splicing and a truncated protein. Objective: To determine the molecular genetics of SMN1 and NAIP genes in SMA from southern India. Materials and Methods: In the present study, 37 patients from the neuromuscular disorders clinic of National Institute of Mental Health and Neurosciences were assayed for the deletions in the SMN1 and NAIP genes using PCR-RFLP methods. Results: Among the SMA Type I patients, 43% showed deletions of SMN1 and NAIP. In patients Type II SMA, 57% showed deletions of the SMN1 exons. Conclusion: Thus, deletions were found to occur in 47.8% of the Type I and II patients. Lower sensitivity of gene deletion study in clinically suspected SMA needs further study as clinical diagnosis of SMA is not gold standard. However, the results do correlate with other studies conducted in India

IRF7 inhibition prevents destructive innate immunity-A target for nonantibiotic therapy of bacterial infections

Boosting innate immunity represents an important therapeutic alternative to antibiotics. However, the molecular selectivity of this approach is a major concern because innate immune responses often cause collateral tissue damage. We identify the transcription factor interferon regulatory factor 7 (IRF-7), a heterodimer partner of IRF-3, as a target for non-antibiotics-based therapy of bacterial infections. We found that the efficient and self-limiting innate immune response to bacterial infection relies on a tight balance between IRF-3 and IRF-7. Deletion of Irf3 resulted in overexpression of Irf7 and led to an IRF-7-driven hyperinflammatory phenotype, which was entirely prevented if Irf7 was deleted. We then identified a network of strongly up-regulated, IRF-7-dependent genes in Irf3-/- mice with kidney pathology, which was absent in Irf7-/- mice. IRF-3 and IRF-7 from infected kidney cell nuclear extracts were shown to bind OAS1, CCL5, andIFNB1 promoter oligonucleotides. These data are consistent in children with lowIRF7 expression in the blood: attenuating IRF7 promoter polymorphisms (rs3758650-T and rs10902179-G) negatively associated with recurrent pyelonephritis. Finally, we identified IRF-7 as a target for immunomodulatory therapy. Administering liposomal Irf7 siRNA to Irf3-/- mice suppressed mucosal IRF-7 expression, and the mice were protected against infection and renal tissue damage. These findings offer a response to the classical but unresolved question of "good versus bad inflammation" and identify IRF7 as a therapeutic target for protection against bacterial infection

Duchenne muscular dystrophy: A clinical, histopathological and genetic study at a neurology tertiary care center in southern India

Background : Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy that affects young boys and the dystrophin gene on the X chromosome has been found to be associated with the disorder. Materials and Methods : In this prospective study, 112 clinically diagnosed DMD patients had muscle biopsy and were tested for exon deletions. Genotyping was also carried out at STR44, STR45, STR49 and STR 50 markers in 15 families. Results : Of the 112 clinically suspected DMD patients, the diagnosis of DMD was confirmed by histopathology and/or genetics in 101 patients. The mean age of onset was 3.1±1.44 years (1-6 years) and the mean age at presentation was 8.0±3.1 years (1.1-18.0 years). Delayed motor milestones were present in 63 (62.3%) patients. The mean creatine kinase value was 11822.64±8206.90 U/L (1240-57,700). Eighty-four patients had muscle biopsy and immunohistochemistry was done in 60 muscle samples, all of which demonstrated absence of dystrophin staining. Of the 60 dystrophin-negative cases, 73% showed deletion of at least one exon. Single exon deletion was found in 20.4%. Distal hotspot Exons 45, 47, 49 and 50 were the commonly deleted xenons and the deletion rates were 36%, 35%, 33.7% and 38.5% respectively. Conclusions : In this study population in south India the deletion rate was 73% and were more frequent in the distal end exon. With the availability of genetic analysis, the first investigation of choice in DMD should be genetic studies and muscle biopsy should be considered only if the genetic tests are negative or not available

Autophagic Marker <i>MAP1LC3B</i> Expression Levels Are Associated with Carotid Atherosclerosis Symptomatology

<div><p>Objectives</p><p>The mechanism by which atheroma plaque becomes unstable is not completely understood to date but analysis of differentially expressed genes in stable versus unstable plaques may provide clues. This will be crucial toward disclosing the mechanistic basis of plaque instability, and may help to identify prognostic biomarkers for ischaemic events. The objective of our study was to identify differences in expression levels of 59 selected genes between symptomatic patients (unstable plaques) and asymptomatic patients (stable plaques).</p><p>Methods</p><p>80 carotid plaques obtained by carotid endarterectomy and classified as symptomatic (>70% stenosis) or asymptomatic (>80% stenosis) were used in this study. The expression levels of 59 genes were quantified by qPCR on RNA extracted from the carotid plaques obtained by endarterectomy and analyzed by means of various bioinformatic tools.</p><p>Results</p><p>Several genes associated with autophagy pathways displayed differential expression levels between asymptomatic and symptomatic (i.e. <i>MAP1LC3B</i>, <i>RAB24</i>, <i>EVA1A</i>). In particular, mRNA levels of <i>MAP1LC3B</i>, an autophagic marker, showed a 5−fold decrease in symptomatic samples, which was confirmed in protein blots. Immune system−related factors and endoplasmic reticulum-associated markers (i.e. <i>ERP27</i>, <i>ITPR1</i>, <i>ERO1LB, TIMP1, IL12B</i>) emerged as differently expressed genes between asymptomatic and symptomatic patients.</p><p>Conclusions</p><p>Carotid atherosclerotic plaques in which <i>MAP1LC3B</i> is underexpressed would not be able to benefit from <i>MAP1LC3B</i>−associated autophagy. This may lead to accumulation of dead cells at lesion site with subsequent plaque destabilization leading to cerebrovascular events. Identified biomarkers and network interactions may represent novel targets for development of treatments against plaque destabilization and thus for the prevention of cerebrovascular events.</p></div

Demographic characteristics of patients included in the study.

<p>Demographic characteristics of patients included in the study.</p

Differences in MAP1LC3B protein expression between symptomatic and asymptomatic.

<p>(A) MAP1LC3B and GAPDH carotid atheroma plaque protein levels were analyzed by Western blot and signal was detected on a ChemiDoc (XRS) detection system (BioRad). The blot shows the results from 5 asymptomatic and 4 symptomatic samples. (B) Densitometric analysis of western blot of LC3-II relative to GAPDH. *P = 0.015 symptomatic vs asymptomatic (Mann-Whitney U test).</p

Molecular enrichment associations – GO: Molecular Functions and KEGG pathways.

<p>Molecular enrichment associations – GO: Molecular Functions and KEGG pathways.</p

Ranking of gene expression markers according to highest fold change in asymptomatic (A) compared with symptomatic (S) samples quantified by Real Time RT−PCR.

<p>The statistical significance was analyzed with the non-parametrical statistical test Mann-Whitney U test (* P≤0.05 and ** P≤0.0001).</p><p>Ranking of gene expression markers according to highest fold change in asymptomatic (A) compared with symptomatic (S) samples quantified by Real Time RT−PCR.</p