Differential temporal and spatial progerin expression during closure of the ductus arteriosus in neonates

Closure of the ductus arteriosus (DA) at birth is essential for the transition from fetal to postnatal life. Before birth the DA bypasses the uninflated lungs by shunting blood from the pulmonary trunk into the systemic circulation. The molecular mechanism underlying DA closure and degeneration has not been fully elucidated, but is associated with apoptosis and cytolytic necrosis in the inner media and intima. We detected features of histology during DA degeneration that are comparable to Hutchinson Gilford Progeria syndrome and ageing. Immunohistochemistry on human fetal and neonatal DA, and aorta showed that lamin A/C was expressed in all layers of the vessel wall. As a novel finding we report that progerin, a splicing variant of lamin A/C was expressed almost selectively in the normal closing neonatal DA, from which we hypothesized that progerin is involved in DA closure. Progerin was detected in 16.2%±7.2 cells of the DA. Progerin-expressing cells were predominantly located in intima and inner media where cytolytic necrosis accompanied by apoptosis will develop. Concomitantly we found loss of α-smooth muscle actin as well as reduced lamin A/C expression compared to the fetal and non-closing DA. In cells of the adjacent aorta, that remains patent, progerin expression was only sporadically detected in 2.5%±1.5 of the cells. Data were substantiated by the detection of mRNA of progerin in the neonatal DA but not in the aorta, by PCR and sequencing analysis. The fetal DA and the non-closing persistent DA did not present with progerin expressing cells. Our analysis revealed that the spatiotemporal expression of lamin A/C and progerin in the neonatal DA was mutually exclusive. We suggest that activation of LMNA alternative splicing is involved in vascular remodeling in the circulatory system during normal neonatal DA closure.     

High eradication rates of Helicobacter pylori infection following sequential therapy: the Israeli experience treating naïve patients

Background: Helicobacter pylori eradication rates following triple therapy are decreasing. Cure rates as low as 57%, mainly to claritromycin resistance, have been reported in Israel. Studies performed in Italy have shown eradication rates of 93%, following sequential therapy. Our aim was to evaluate the effect of sequential therapy on eradication rates of H. pylori in naïve Israeli patients. Material and Methods: Consecutive patients referred for esophagogastroduodenoscopy with a positive rapid urease test and positive ¹³C urea breath test were included. Patients received omeprazole 20 mg bid and amoxicillin 1 g bid for 5 days followed by omeprazole 20 mg bid, clarithromycin 500 mg bid and tinidazole 500 mg bid for the subsequent 5 days. A second ¹³C urea breath test was performed at least 4 weeks after completion of therapy. Patients were asked to avoid antibiotics, bismuth compounds or proton pump inhibitor until after the second ¹³C urea breath test. Adverse effects were documented by a questionnaire. Results: One hundred and twenty‐four patients (mean age 56.1 ± 12.5 years, 55.6% women) were included; 120/124 (96.8%) completed treatment and performed the second ¹³C urea breath test. Two patients (1.6%) were lost to follow‐up; 2 (1.6%) were noncompliant with study regulations. One hundred and fifteen patients achieved eradication of H. pylori. The eradication rate was 95.8% by per protocol analysis and 92.7% by intention to treat analysis. Conclusion: The sequential regimen attained significantly higher eradication rates in naïve patients than usually reported for conventional triple therapy. Sequential therapy may be an alternative first‐line therapy in eradicating H. pylori in Israel.     

Translocation of the Drosophila transient receptor potential-like (TRPL) channel requires both the N- and C-terminal regions together with sustained Ca2+ entry

In Drosophila photoreceptors the transient receptor potential-like (TRPL), but not the TRP channels undergo light-dependent translocation between the rhabdomere and cell body. Here we studied which of the TRPL channel segments are essential for translocation and why the TRP channels are required for inducing TRPL translocation. We generated transgenic flies expressing chimeric TRP and TRPL proteins that formed functional light-activated channels. Translocation was induced only in chimera containing both the N- and C-terminal segments of TRPL. Using an inactive trp mutation and overexpressing the Na(+)/Ca(2+) exchanger revealed that the essential function of the TRP channels in TRPL translocation is to enhance Ca(2+)-influx. These results indicate that motifs present at both the N and C termini as well as sustained Ca(2+) entry are required for proper channel translocation.     

Primary ciliary dyskinesia caused by homozygous mutation in DNAL1, encoding dynein light chain 1

In primary ciliary dyskinesia (PCD), genetic defects affecting motility of cilia and flagella cause chronic destructive airway disease, randomization of left-right body asymmetry, and, frequently, male infertility. The most frequent defects involve outer and inner dynein arms (ODAs and IDAs) that are large multiprotein complexes responsible for cilia-beat generation and regulation, respectively. Although it has long been suspected that mutations in DNAL1 encoding the ODA light chain1 might cause PCD such mutations were not found. We demonstrate here that a homozygous point mutation in this gene is associated with PCD with absent or markedly shortened ODA. The mutation (NM_031427.3: c.449A>G; p.Asn150Ser) changes the Asn at position150, which is critical for the proper tight turn between the β strand and the α helix of the leucine-rich repeat in the hydrophobic face that connects to the dynein heavy chain. The mutation reduces the stability of the axonemal dynein light chain 1 and damages its interactions with dynein heavy chain and with tubulin. This study adds another important component to understanding the types of mutations that cause PCD and provides clinical information regarding a specific mutation in a gene not yet known to be associated with PCD.     

SIAH proteins regulate the degradation and intra‐mitochondrial aggregation of PINK1: Implications for mitochondrial pathology in Parkinson's disease

Parkinson''s disease (PD) is characterized by degeneration of neurons, particularly dopaminergic neurons in the substantia nigra. PD brains show accumulation of α‐synuclein in Lewy bodies and accumulation of dysfunctional mitochondria. However, the mechanisms leading to mitochondrial pathology in sporadic PD are poorly understood. PINK1 is a key for mitophagy activation and recycling of unfit mitochondria. The activation of mitophagy depends on the accumulation of uncleaved PINK1 at the outer mitochondrial membrane and activation of a cascade of protein ubiquitination at the surface of the organelle. We have now found that SIAH3, a member of the SIAH proteins but lacking ubiquitin‐ligase activity, is increased in PD brains and cerebrospinal fluid and in neurons treated with α‐synuclein preformed fibrils (α‐SynPFF). We also observed that SIAH3 is aggregated together with PINK1 in the mitochondria of PD brains. SIAH3 directly interacts with PINK1, leading to their intra‐mitochondrial aggregation in cells and neurons and triggering a cascade of toxicity with PINK1 inactivation along with mitochondrial depolarization and neuronal death. We also found that SIAH1 interacts with PINK1 and promotes ubiquitination and proteasomal degradation of PINK1. Similar to the dimerization of SIAH1/SIAH2, SIAH3 interacts with SIAH1, promoting its translocation to mitochondria and preventing its ubiquitin‐ligase activity toward PINK1. Our results support the notion that the increase in SIAH3 and intra‐mitochondrial aggregation of SIAH3‐PINK1 may mediate α‐synuclein pathology by promoting proteotoxicity and preventing the elimination of dysfunctional mitochondria. We consider it possible that PINK1 activity is decreased in sporadic PD, which impedes proper mitochondrial renewal in the disease.     

Soil Microbial Diversity in the Vicinity of a Negev Desert Shrub��Reaumuria negevensis

The Negev Desert is characterized by low soil-water availability and organic matter content, as well as important factors significantly influencing soil biological activity. In order to overcome the xeric environment, plant and soil biota have evolutionarily developed, over time, ecophysiological abilities that help them fulfill their biological role and function. Microorganisms are known as a major part of the ecosystem's total biomass and play an important role in decomposition processes and the nutrient cycle. Perennial shrubs have been found to play an important role as organic matter suppliers and as a physical barrier prolonging biological activity of microbial communities. Soil samples were collected monthly, from November 2006 to November 2007, from a 0 to 10-cm depth under the canopies of Reaumuria negevensis and from open areas (control) in order to evaluate abiotic components and microbial variables on a temporal basis. H' values, evenness, and β diversity (S?rensen's similarity) were determined by a molecular method based on sequencing. Water availability, organic matter content, and total soluble nitrogen were higher in soil samples collected in the vicinity of R. negevensis than in samples collected in open areas. Our study also indicated that, in spite of the similarity between H' values of soil samples collected in the vicinity of R. negevensis and the open area, a low percentage of similarity was found between the soil bacterial populations. These results support the hypothesis that distribution of resources in the environment under R. negevensis shrubs varies in space and time and also influences soil microbial diversity and the abiotic environmental role.     

Pheromone-induced morphogenesis and gradient tracking are dependent on the MAPK Fus3 binding to Gα

Mitogen-activated protein kinase (MAPK) pathways control many cellular processes, including differentiation and proliferation. These pathways commonly activate MAPK isoforms that have redundant or overlapping function. However, recent studies have revealed circumstances in which MAPK isoforms have specialized, nonoverlapping roles in differentiation. The mechanisms that underlie this specialization are not well understood. To address this question, we sought to establish regulatory mechanisms that are unique to the MAPK Fus3 in pheromone-induced mating and chemotropic fate transitions of the budding yeast Saccharomyces cerevisiae. Our investigations reveal a previously unappreciated role for inactive Fus3 as a potent negative regulator of pheromone-induced chemotropism. We show that this inhibitory role is dependent on inactive Fus3 binding to the α-subunit of the heterotrimeric G-protein. Further analysis revealed that the binding of catalytically active Fus3 to the G-protein is required for gradient tracking and serves to suppress cell-to-cell variability between mating and chemotropic fates in a population of pheromone-responding cells.