soheil aghamohammadzadeh - Academia.edu (original) (raw)

Papers by soheil aghamohammadzadeh

Journal of Cystic Fibrosis, 2016

Post-hoc analysis of a randomized, double-blind, placebo-controlled, phase 3 study showed a signi... more Post-hoc analysis of a randomized, double-blind, placebo-controlled, phase 3 study showed a significant difference in relative change from baseline in %-predicted FEV 1 favouring the ataluren-treated group vs placebo in patients not using chronic inhaled tobramycin (non-TOBI). As exacerbations are key drivers of disease progression, the effect of ataluren on exacerbations in nmCF patients was studied. Methods: A post-hoc analysis was conducted on the effect of ataluren on exacerbations, as defined by the modified Fuchs' criteria, in non-TOBI patients (N = 146). Rates and rate ratio were estimated using a generalized linear model. Results: In non-TOBI patients, there was a significant 40% reduction in mean exacerbation rate at 48 weeks for patients on ataluren vs placebo (Table). Of non-TOBI patients receiving placebo, 53 of 74 (72%) patients were not on any inhaled antibiotics at baseline. Median time to first pulmonary exacerbation was ±280 days for ataluren vs ±165 days for placebo. There was a 50.7% reduction in mean duration of hospitalization in non-TOBI patients on ataluren vs placebo (3.3 days for ataluren vs 6.5 days for placebo). Mean exacerbation rate, 48 weeks (95% CI) Ataluren Placebo Rate ratio P value Reduction with ataluren ITT (N = 232) 1.42 (1.05-1.79) 1.78 (1.38-2.17) 0.77 (0.57-1.05) 0.0992 23% Non-TOBI (N = 146) 1.42 (0.92-1.93) 2.18 (1.62-2.74) 0.60 (0.42-0.86) 0.0061 40%

(A) Wild type and abp1Δ cells were grown to mid log phase. Half of th... more (A) Wild type and abp1Δ cells were grown to mid log phase. Half of the cells were incubated with 25 µM Lat-A. LY was added for 90 minutes as described. Localization of stain was categorized as being at the plasma membrane, endosomes or vacuoles. Error bars are std deviation. (B) Representative images from the cells visualized. Bar = 5 µm.</p

American Journal of Physiology-Lung Cellular and Molecular Physiology

We found that forskolin-induced swelling in G550X-CFTR patient-derived intestinal organoids (PDOs... more We found that forskolin-induced swelling in G550X-CFTR patient-derived intestinal organoids (PDOs) was significantly higher than in G542X-CFTR PDOs after treatment with ELX-02. Tryptophan (W) was the sole amino acid inserted in the G550X position after readthrough. Resulting G550W-CFTR protein exhibited supernormal CFTR activity, PKA sensitivity, and open probability. These results show that aminoglycoside-induced readthrough of G550X produces greater CFTR function because of the gain-of-function properties of the CFTR readthrough product.

(A) Cells co-expressing Sla1-mRFP and Sla2-GFP (KAY1734) were imaged and composition of ... more (A) Cells co-expressing Sla1-mRFP and Sla2-GFP (KAY1734) were imaged and composition of spots was analysed. Kymographs show examples of puncta that show the two proteins together and with Sla2-GFP alone. Kymographs are from full movie (120 seconds) (B) Cells expressing Sla1-GFP (KAY733) were incubated with FM4-64FX for 5 minutes and imaged. Examples of both GFP only and FM4-64 only puncta invaginating are shown in kymographs. Kymographs are from full movie (120 seconds). The images are stills taken from supplemental movie at the times indicated. Scale bar = 2 µm.</p

Human Molecular Genetics, 2015

Lysosomal dysfunction plays a central role in the pathogenesis of several neurodegenerative disor... more Lysosomal dysfunction plays a central role in the pathogenesis of several neurodegenerative disorders, including Parkinson's disease (PD). Several genes linked to genetic forms of PD, including leucine-rich repeat kinase 2 (LRRK2), functionally converge on the lysosomal system. While mutations in LRRK2 are commonly associated with autosomal-dominant PD, the physiological and pathological functions of this kinase remain poorly understood. Here, we demonstrate that LRRK2 regulates lysosome size, number and function in astrocytes, which endogenously express high levels of LRRK2. Expression of LRRK2 G2019S, the most common pathological mutation, produces enlarged lysosomes and diminishes the lysosomal capacity of these cells. Enlarged lysosomes appears to be a common phenotype associated with pathogenic LRRK2 mutations, as we also observed this effect in cells expressing other LRRK2 mutations; R1441C or Y1699C. The lysosomal defects associated with these mutations are dependent on both the catalytic activity of the kinase and autophosphorylation of LRRK2 at serine 1292. Further, we demonstrate that blocking LRRK2's kinase activity, with the potent and selective inhibitor PF-06447475, rescues the observed defects in lysosomal morphology and function. The present study also establishes that G2019S mutation leads to a reduction in lysosomal pH and increased expression of the lysosomal ATPase ATP13A2, a gene linked to a parkinsonian syndrome (Kufor-Rakeb syndrome), in brain samples from mouse and human LRRK2 G2019S carriers. Together, these results demonstrate that PD-associated LRRK2 mutations perturb lysosome function in a kinase-dependent manner, highlighting the therapeutic promise of LRRK2 kinase inhibitors in the treatment of PD.

Fungal Biology Reviews, 2010

Actin is an essential protein in yeast and functions in the fundamental processes of cell polarit... more Actin is an essential protein in yeast and functions in the fundamental processes of cell polarity, cytokinesis and endocytosis. Actin performs this role in concert with a myriad of actin-binding proteins. Different proteins drive polymerisation of actin into filaments, organise filaments into higher order structures such as bundles, trigger severing of filaments, or depolymerisation of filaments to the monomer state. Recent advances in imaging, the development of fluorescent fusion protein technology, coupled with genetic and molecular biology approaches, have driven progress in our understanding of many components of the actin cytoskeleton and how their function is critical to the mechanism of endocytosis in yeast.

PLoS ONE, 2014

Clathrin-mediated endocytosis (CME) is a well characterized pathway in both yeast and mammalian c... more Clathrin-mediated endocytosis (CME) is a well characterized pathway in both yeast and mammalian cells. An increasing number of alternative endocytic pathways have now been described in mammalian cells that can be both clathrin, actin, and Arf6-dependent or independent. In yeast, a single clathrin-mediated pathway has been characterized in detail. However, disruption of this pathway in many mutant strains indicates that other uptake pathways might exist, at least for bulk lipid and fluid internalization. Using a combination of genetics and live cell imaging, here we show evidence for a novel endocytic pathway in S. cerevisiae that does not involve several of the proteins previously shown to be associated with the 'classic' pathway of endocytosis. This alternative pathway functions in the presence of low levels of the actin-disrupting drug latrunculin-A which inhibits movement of the proteins Sla1, Sla2, and Sac6, and is independent of dynamin function. We reveal that in the absence of the 'classic' pathway, the actin binding protein Abp1 is now essential for bulk endocytosis. This novel pathway appears to be distinct from another described alternative endocytic route in S. cerevisiae as it involves at least some proteins known to be associated with cortical actin patches rather than being mediated at formin-dependent endocytic sites. These data indicate that cells have the capacity to use overlapping sets of components to facilitate endocytosis under a range of conditions.

Traffic, 2012

Dynamins are a conserved family of proteins involved in many membrane fusion and fission events. ... more Dynamins are a conserved family of proteins involved in many membrane fusion and fission events. Previously, the dynamin-related protein Vps1 was shown to localize to endocytic sites, and yeast carrying deletions for genes encoding both the BAR domain protein Rvs167 and Vps1 had a more severe endocytic scission defect than either deletion alone. Vps1 and Rvs167 localize to endocytic sites at the onset of invagination and disassemble concomitant with inward vesicle movement. Rvs167-GFP localization is reduced in cells lacking vps1 suggesting that Vps1 influences Rvs167 association with the endocytic complex. Unlike classical dynamins, Vps1 does not have a proline-arginine domain that could interact with SH3 domain-containing proteins. Thus, while Rvs167 has an SH3 domain, it is not clear how an interaction would be mediated. Here, we demonstrate an interaction between Rvs167 SH3 domain and the single type I SH3-binding motif in Vps1. Mutant Vps1 that cannot bind Rvs167 rescues all membrane fusion/fission functions associated with Vps1 except for endocytic function, demonstrating the specificity and mechanistic importance of the interaction. In vitro, an Rvs161/Rvs167 heterodimer can disassemble Vps1 oligomers. Overall, the data support the idea that Vps1 and the amphiphysins function together to mediate scission during endocytosis in yeast.

Nature Cell Biology, 2009

This is a repository copy of Differential requirements for actin during yeast and mammalian endoc... more This is a repository copy of Differential requirements for actin during yeast and mammalian endocytosis.

Journal of Biological Chemistry, 2008

The yeast SM22 homologue Scp1 has previously been shown to act as an actin-bundling protein in vi... more The yeast SM22 homologue Scp1 has previously been shown to act as an actin-bundling protein in vitro. In cells, Scp1 localizes to the cortical actin patches that form as part of the invagination process during endocytosis, and its function overlaps with that of the well characterized yeast fimbrin homologue Sac6p. In this work we have used live cell imaging to demonstrate the importance of key residues in the Scp1 actin interface. We have defined two actin binding domains within Scp1 that allow the protein to both bind and bundle actin without the need for dimerization. Green fluorescent protein-tagged mutants of Scp1 also indicate that actin localization does not require the putative phosphorylation site Ser-185 to be functional. Deletion of SCP1 has few discernable effects on cell growth and morphology. However, we reveal that scp1 deletion is compensated for by up-regulation of Sac6. Furthermore, Scp1 levels are increased in the absence of sac6. The presence of compensatory pathways to up-regulate Sac6 or Scp1 levels in the absence of the other suggest that maintenance of sufficient bundling activity is critical within the cell. Analysis of cortical patch assembly and movement during endocytosis reveals a previously undetected role for Scp1 in movement of patches away from the plasma membrane. Additionally, we observe a dramatic increase in patch lifetime in a strain lacking both sac6 and scp1, demonstrating the central role played by actin-bundling proteins in the endocytic process.

Journal of Cell Science, 2010

Dynamins are a conserved family of proteins involved in membrane fusion and fission. Although mam... more Dynamins are a conserved family of proteins involved in membrane fusion and fission. Although mammalian dynamins are known to be involved in several membrane-trafficking events, the role of dynamin-1 in endocytosis is the best-characterised role of this protein family. Despite many similarities between endocytosis in yeast and mammalian cells, a comparable role for dynamins in yeast has not previously been demonstrated. The reported lack of involvement of dynamins in yeast endocytosis has raised questions over the general applicability of the current yeast model of endocytosis, and has also precluded studies using well-developed methods in yeast, to further our understanding of the mechanism of dynamin function during endocytosis. Here, we investigate the yeast dynamin-like protein Vps1 and demonstrate a transient burst of localisation to sites of endocytosis. Using live-cell imaging of endocytic reporters in strains lacking vps1, and also electron microscopy and biochemical approac...

Development

When the axons of primary sensory neurons project into the embryonic mammalian spinal cord, they ... more When the axons of primary sensory neurons project into the embryonic mammalian spinal cord, they bifurcate and extend rostrocaudally before sending collaterals to specific laminae according to neuronal subclass. The specificity of this innervation has been suggested to be the result both of differential sensitivity to chemorepellants expressed in the ventral spinal cord and of the function of Ig-like neural cell adhesion molecules in the dorsal horn. The relationship between these mechanisms has not been addressed. Focussing on the pathfinding of TrkA+ NGF-dependent axons, we demonstrate for the first time that their axons project prematurely into the dorsal horn of both L1 and TAG-1 knockout mice. We show that axons lacking TAG-1, similar to those lacking L1, are insensitive to wild-type ventral spinal cord (VSC)-derived chemorepellants, indicating that adhesion molecule function is required in the axons, and that this loss of response is explained in part by loss of response to Se...