Search

Your search keyword '"Al Tobi, Mohammed"' showing total 20 results
Start Over Author "Al Tobi, Mohammed"
20 results on '"Al Tobi, Mohammed"'

3. Consequences of tyrosine phosphorylation of Syntaxin4 and Munc18c on GLUT4 trafficking

Author

Al Tobi, Mohammed Nasser Rashid

Subjects
Q Science (General), RZ Other systems of medicine
Abstract

Glucose homeostasis is regulated by the opposing actions of insulin and glucagon; insulin facilitates rapid glucose uptake from the blood stream to muscle and adipose cells. These tissues express the facilitative glucose transporter (GLUT4), which in response to insulin is translocated from intracellular compartments to the plasma membrane (PM) allowing glucose entry to cells. GLUT4 undergoes a complex intracellular trafficking itinerary, including recycling to and from the PM, but in the absence of insulin is mainly stored in GLUT4 storage vesicles (GSVs). When insulin binds its receptor, a complicated signalling cascade is initiated which results in the tethering, docking and fusion of GSVs to the PM. Fusion of the GSVs with the plasma membrane is mediated by SNARE proteins. The formation of a SNARE complex composed of Syntaxin4 (Sx4) and SNAP23 localised to the PM and VAMP2 on GSVs is a key event; the formation of this complex is in turn regulated by the Sec1/Munc18 protein, Munc18c. It has been shown that insulin stimulation leads to phosphorylation of Sx4 at two sites (Y115 and Y251) and Munc18c at Y521. The stoichiometry and order of phosphorylation are not yet known, and the biological consequences of this action to be uncovered. Therefore, the current study sought to ascertain the functional consequences of SNARE protein phosphorylation on GLUT4 trafficking. The approaches used include in vitro assessment of recombinant SNARE proteins and studies in vivo using 3T3-L1 adipocytes. The results of this study confirmed that tyrosine 115 and 251 of syntaxin4 are phosphorylated in response to insulin in 3T3-L1 adipocytes; however, phosphorylation of Munc18c was ambiguous. Subsequently, phosphomimetic recombinant SNARE proteins were expressed and ternary SNARE complex formation was successfully recapitulated in vitro and the complex found to be SDS and heat resistant. Phosphomimetic syntaxin4 mutants showed increased formation of SNARE complexes, notably double phosphomimetic mutant. Moreover, binary interactions with other SNAREs (SNAP23 and VAMP2) revealed tighter binding and higher affinity of the double phosphomimetic syntaxin4 compared to wild-type syntaxin4. Additional spectroscopic evidences suggest these differences are due to conformational changes and syntaxin4 mutants are more likely to be in the open form especially the double phosphomimetic mutant. In order to translate in vitro findings into cell models, in vivo intervention tools were generated including phospho-specific antibodies against phosphorylated residues in syntaxin4 and lentivirus particles for 3T3-L1 adipocytes infection. Antibodies validated on recombinant proteins phosphorylated using recombinant insulin receptor tyrosine kinase indicated they are functional and specific. Efforts dedicated towards optimizing working conditions for phospho-specific antibodies using adipocyte lysates were extensively examined, yet signals detected were generally found to be non-specific. A non-intrusive protein-protein interaction protocol, proximity ligation assay, was used to detect insulin-stimulated phosphorylation in adipocytes. A positive signal was detected confirming antibodies functionality in this assay; further work will be required to optimize this. Lentiviruses were used to over-express phosphomimetic mutants of syntaxin4 in 3T3-L1 adipocytes and Hela cells. The functionality of the transfected syntaxin4 mutants was assessed by measuring basal and insulin-stimulated glucose uptake. Infected native 3T3-L1 adipocytes showed a trend towards an increase in glucose uptake under basal conditions with no effect observed on the maximal insulin-stimulated rate of glucose transport. We speculate this may reflect the presence of the endogenous Sx4 molecules masking any effects of mutant over-expression thus Sx4 knockout cell lines was considered as an alternative experimental system. Sx4 overexpression rescued insulin-stimulated glucose uptake in Sx4 knockout 3T3-L1 cells and was significantly enhanced in cells expressing the double phosphomimetic mutant. Finally, our work showed that the native Munc18c native mouse gene sequence expressed poorly in bacteria; hence we used a gene-enhanced sequence that was found to express well and purify effectively. CD spectroscopy showed similar structures of expressed Munc18c using either sequences. Phosphomimetic Munc18c (Y521E) binds with higher affinity both wild type and double phosphomimetic syntaxin4 compared to wild type Munc18c. The data presented in this study suggest strongly that phosphorylation influences GLUT4 trafficking by altering the frequency and affinity of SNARE protein interactions. Such findings enrich knowledge about the mechanism of GLUT4 trafficking thus ultimately could help in understanding type 2 diabetes.

Published
2018

4. Seroprevalence of SARS-CoV-2 antibodies in the general population of Oman: results from four successive nationwide sero-epidemiological surveys

Author

Al-Abri, Seif Salem, Al-Wahaibi, Adil, Al-Kindi, Hanan, Kurup, Padmamohan J, Al-Maqbali, Ali, Al-Mayahi, Zayid, Al-Tobi, Mohammed Hamed, Al-Katheri, Salim Habbash, Albusaidi, Sultan, Al-Sukaiti, Mahmood Humaid, Al Balushi, Ahmed Yar Mohammed, Abdelgadir, Iyad Omer, Al-Shehi, Nawal, Morkos, Essam, Al-Maani, Amal, Al-Rawahi, Bader, Alyaquobi, Fatma, Alqayoudhi, Abdullah, Al-Harthy, Khalid, Al-Khalili, Sulien, Al-Rashdi, Azza, Al-Shukri, Intisar, Al Ghafri, Thamra S., Al-Hashmi, Fatma, Al Jassasi, Saeed Mussalam, Alshaqsi, Nasser, Mitra, Nilanjan, Al Aamry, Humaid Suhail, Shah, Parag, Al Marbouai, Hanan Hassan, Al Araimi, Amany Hamed, Kair, Ismail Mohammed, Al Manji, Asim Mohammed, Almallak, Ahmed Said, Al Alawi, Fatma Khamis, Vaidya, Vidyanand, Muqeetullah, Muhammad, Alrashdi, Hanan, Al Jamoudi, Saud Said Nassir, Alshaqsi, Asila, Al Sharji, Abdullah, Al Shukeiri, Hamida, Al-Abri, Badr, Al-Rawahi, Sulaiman, Al-Lamki, Said H., Al-Manji, Abdulla, and Al-Jardani, Amina

Published
2021
Full Text
View/download PDF

5. Knockout of syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion.

Author

Black, Hannah L., Livingstone, Rachel, Mastick, Cynthia C., Al Tobi, Mohammed, Taylor, Holly, Geiser, Angéline, Stirrat, Laura, Kioumourtzoglou, Dimitrios, Petrie, John R., Boyle, James G., Bryant, Nia J., and Gould, Gwyn W.

Subjects
ADIPONECTIN, SECRETION, FAT cells, GLUCOSE transporters, ADIPOKINES, COATED vesicles
Abstract

Adipocytes are key to metabolic regulation, exhibiting insulinstimulated glucose transport that is underpinned by the insulinstimulated delivery of glucose transporter type 4 (SLC2A4, also known and hereafter referred to as GLUT4)-containing vesicles to the plasmamembranewhere they dock and fuse, and increase cell surface GLUT4 levels. Adipocytokines, such as adiponectin, are secreted via a similarmechanism.We used genome editing to knock out syntaxin-4, a protein reported to mediate fusion between GLUT4-containing vesicles and the plasma membrane in 3T3-L1 adipocytes. Syntaxin-4 knockout reduced insulin-stimulated glucose transport and adiponectin secretion by ~50% and reduced GLUT4 levels. Ectopic expression of haemagglutinin (HA)-tagged GLUT4 conjugated to GFP showed that syntaxin-4-knockout cells retain significant GLUT4 translocation capacity, demonstrating that syntaxin-4 is dispensable for insulinstimulated GLUT4 translocation. Analysis of recycling kinetics revealed only a modest reduction in the exocytic rate of GLUT4 in knockout cells, and little effect on endocytosis. These analyses demonstrate that syntaxin-4 is not always rate limiting for GLUT4 delivery to the cell surface. In sum, we show that syntaxin-4 knockout results in reduced insulin-stimulated glucose transport, depletion of cellular GLUT4 levels and inhibition of adiponectin secretion but has only modest effects on the translocation capacity of the cells. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

6. Electronic nicotine delivery systems exhibit reduced bronchial epithelial cells toxicity compared to cigarette: the Replica Project

Author

Caruso, Massimo, Emma, Rosalia, Distefano, Alfio, Rust, Sonja, Poulas, Konstantinos, Zadjali, Fahad, Giordano, Antonio, Volarevic, Vladislav, Mesiakaris, Konstantinos, Al Tobi, Mohammed, Boffo, Silvia, Arsenijevic, Aleksandar, Zuccarello, Pietro, Giallongo, Cesarina, Ferrante, Margherita, Polosa, Riccardo, and Li Volti, Giovanni

Published
2021
Full Text
View/download PDF

8. Nicotine measurement on Cambridge Filter PADs: an interlaboratory comparison to evaluate exposure by different electronic devices and traditional cigarette

Author

Zuccarello, Pietro, Emma, Rosalia, Caruso, Massimo, Pulvirenti, Roberta, Rust, Sonja, Kostantinos, Poulas, Zadjali, Fahad, Boffo, Silvia, Volarevic, Vladislav, Lesmana, Ronny, Abdulkhakov, Sayar R, Mesiakaris, Konstantinos, Al Tobi, Mohammed, Giordano, Antonio, Arsenijevic, Aleksandar, Barliana, Melisa I, Kitaeva, Kristina V, Polosa, Riccardo, Li Volti, Giovanni, and Ferrante, Margherita

Abstract

Inter-laboratory comparison is widely used to ensure quality control among laboratories. In in vitro toxicology studies for tobacco harm reduction (THR), exposure system performance and laboratory proficiency along with product smoke and aerosol stream are tested for variability to assess accuracy. Here we aim to test a novel inter-laboratory setup created in a new collaborative research group using identical and small footprint systems- in order to minimize variability factors and increase reproducibility.Seven independent laboratories from different geographical areas tested the aerosol and smoke stream and exposure system performance (LM1 and LM4E) using Cambridge Filter Pad (CFP) trapping techniques. We tested 1R6F reference cigarettes, two electronic cigarettes (Vype e-Pen and Vype e-Stick Maxx), and two tobacco heating products (IQOS and Glo™) under the appropriate ISO and/or HCI regimes. Nicotine quantification was performed by GC-FID at the laboratory of the leading center. The performance of participant laboratories was assessed by z-score values obtained from results either in relation to the mean and standard deviation of total participants or in relation to the reference leading center. Z-Scores were satisfactory when |z| ≤ 2, questionable when 2 < |z| < 3 and, unsatisfactory when |z| ≥ 3. In the first evaluation, for all the tested devices, Z- scores values generated by dosimetry data ranged from -2 to +2. However, high intra-laboratory variability (RSD> 10%) was observed for almost all laboratories. In the second, data showed borderline and unsatisfactory exposure performances versus LAB-A. Particularly, Z-scores ≥ 3 were observed once for LAB-B (e-Stick exposure) and LAB-G (e-Pen exposure), twice for LAB-C (1R6F-ISO and e-Stick exposures) and LAB-E (e-Pen and e-Stick exposures), and three times for LAB-F (1R6F-HCI, e-Pen, and Glo exposures).This study demonstrates that nicotine dosimetry is a fundamental method for quality assurance of smoke/vapor run exposure in the early stage of an interlaboratory study, allowing the identification and possibly the resolution of gaps. Extended practice sessions on exposure runs and several rounds of nicotine dosimetry testing should be planned to keep in check overall equipment and operator performance.

Published
2022

9. Electronic Nicotine Delivery Systems Exhibit LowerToxicity Compared to Cigarettes: “The Replica Study Experience”

Author

Distefano, Alfio, primary, Caruso, Massimo, additional, Emma, Rosalia, additional, Rust, Sonja, additional, Poulas, Konstantinos, additional, Zadjali, Fahad, additional, Boffo, Silvia, additional, Volarevic, Vladislav, additional, Mesiakaris, Konstantinos, additional, Karanasios, Georgios, additional, Al Tobi, Mohammed, additional, Albalushi, Najwa, additional, Giordano, Antonio, additional, Canciello, Angelo, additional, Arsenijevic, Aleksandar, additional, Ilic, Aleksandar, additional, Caruso, Tancredi, additional, Carota, Giuseppe, additional, Spampinato, Maria R., additional, Zuccarello, Pietro, additional, Ferrante, Margherita, additional, Polosa, Riccardo, additional, and Li Volti, Giovanni, additional

Published
2022
Full Text
View/download PDF

10. Knockout of syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion

Author

Black, Hannah L., primary, Livingstone, Rachel, additional, Mastick, Cynthia C., additional, Al Tobi, Mohammed, additional, Taylor, Holly, additional, Geiser, Angéline, additional, Stirrat, Laura, additional, Kioumourtzoglou, Dimitrios, additional, Petrie, John R., additional, Boyle, James G., additional, Bryant, Nia J., additional, and Gould, Gwyn W., additional

Published
2022
Full Text
View/download PDF

11. Knockout of syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion.

Author

Black, Hannah L., Livingstone, Rachel, Mastick, Cynthia C., Al Tobi, Mohammed, Taylor, Holly, Geiser, Angéline, Stirrat, Laura, Kioumourtzoglou, Dimitrios, Petrie, John R., Boyle, James G., Bryant, Nia J., and Gould, Gwyn W.

Subjects
ADIPONECTIN, SECRETION, GLUCOSE transporters, ADIPOKINES, METABOLIC regulation, ADIPOGENESIS, FAT cells
Abstract

Adipocytes are key to metabolic regulation, exhibiting insulinstimulated glucose transport that is underpinned by the insulinstimulated delivery of glucose transporter type 4 (SLC2A4, also known and hereafter referred to as GLUT4)-containing vesicles to the plasmamembranewhere they dock and fuse, and increase cell surface GLUT4 levels. Adipocytokines, such as adiponectin, are secreted via a similarmechanism. We used genome editing to knock out syntaxin-4, a protein reported to mediate fusion between GLUT4-containing vesicles and the plasma membrane in 3T3-L1 adipocytes. Syntaxin-4 knockout reduced insulin-stimulated glucose transport and adiponectin secretion by ~50% and reduced GLUT4 levels. Ectopic expression of haemagglutinin (HA)-tagged GLUT4 conjugated to GFP showed that syntaxin-4-knockout cells retain significant GLUT4 translocation capacity, demonstrating that syntaxin-4 is dispensable for insulinstimulated GLUT4 translocation. Analysis of recycling kinetics revealed only a modest reduction in the exocytic rate of GLUT4 in knockout cells, and little effect on endocytosis. These analyses demonstrate that syntaxin-4 is not always rate limiting for GLUT4 delivery to the cell surface. In sum, we show that syntaxin-4 knockout results in reduced insulin-stimulated glucose transport, depletion of cellular GLUT4 levels and inhibition of adiponectin secretion but has only modest effects on the translocation capacity of the cells. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

13. Ameliorative Effect of Sesamin in Cisplatin-Induced Nephrotoxicity in Rats by Suppressing Inflammation, Oxidative/Nitrosative Stress, and Cellular Damage.

Author

ALI, Badreldin H., AL SALAM, Suhail, AL SULEIMANI, Yousuf, AL ZA'ABI, Mohamed, ASHIQUE, Mohammed, MANOJ, Priyadarsini, SUDHADEVI, Manjusha, AL TOBI, Mohammed, and NEMMAR, Abderrahim

Subjects
NEPHROTOXICOLOGY, RATS, OXIDATIVE stress, INFLAMMATION, ENDOPLASMIC reticulum, SESAME oil
Abstract

Nephrotoxicity of cisplatin (CP) involves renal oxidative stress and inflammation, and sesamin (a major liganin in many plants) has strong antioxidant and antiinflammatory actions. Therefore, we investigated here the possible mitigative action of sesamin on CP nephrotoxicity in rats. Sesamin was given orally (5 mg/kg/day, 10 days), and on the 7th day, some of the treated rats were injected intraperitoneally with either saline or CP (5 mg/kg). On the 11th day, rats were sacrificed, and blood and urine samples and kidneys were collected for biochemical estimation of several traditional and novel indices of renal damage in plasma and urine, several oxidative and nitrosative indices in kidneys, and assessment of histopathological renal damage. CP significantly and adversely altered all the physiological, biochemical and histopathological indices of renal function measured. Kidneys of CP-treated rats had a moderate degree of necrosis. This was markedly lessened when CP was given simultaneously with sesamin. Sesamin treatment did not significantly alter the renal CP concentration. The results suggested that sesamin had ameliorated CP nephrotoxicity in rats by reversing the CP-induced oxidative stress and inflammation. Pending further pharmacological and toxicological studies sesamin may be considered a potentially useful nephroprotective agent. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

16. Consequences of tyrosine phosphorylation of Syntaxin4 and Munc18c on GLUT4 trafficking

Author

Al Tobi, Mohammed Nasser Rashid and Al Tobi, Mohammed Nasser Rashid

Abstract

Glucose homeostasis is regulated by the opposing actions of insulin and glucagon; insulin facilitates rapid glucose uptake from the blood stream to muscle and adipose cells. These tissues express the facilitative glucose transporter (GLUT4), which in response to insulin is translocated from intracellular compartments to the plasma membrane (PM) allowing glucose entry to cells. GLUT4 undergoes a complex intracellular trafficking itinerary, including recycling to and from the PM, but in the absence of insulin is mainly stored in GLUT4 storage vesicles (GSVs). When insulin binds its receptor, a complicated signalling cascade is initiated which results in the tethering, docking and fusion of GSVs to the PM. Fusion of the GSVs with the plasma membrane is mediated by SNARE proteins. The formation of a SNARE complex composed of Syntaxin4 (Sx4) and SNAP23 localised to the PM and VAMP2 on GSVs is a key event; the formation of this complex is in turn regulated by the Sec1/Munc18 protein, Munc18c. It has been shown that insulin stimulation leads to phosphorylation of Sx4 at two sites (Y115 and Y251) and Munc18c at Y521. The stoichiometry and order of phosphorylation are not yet known, and the biological consequences of this action to be uncovered. Therefore, the current study sought to ascertain the functional consequences of SNARE protein phosphorylation on GLUT4 trafficking. The approaches used include in vitro assessment of recombinant SNARE proteins and studies in vivo using 3T3-L1 adipocytes. The results of this study confirmed that tyrosine 115 and 251 of syntaxin4 are phosphorylated in response to insulin in 3T3-L1 adipocytes; however, phosphorylation of Munc18c was ambiguous. Subsequently, phosphomimetic recombinant SNARE proteins were expressed and ternary SNARE complex formation was successfully recapitulated in vitro and the complex found to be SDS and heat resistant. Phosphomimetic syntaxin4 mutants showed increased formation of SNARE complexes, notably double phos

17. Consequences of tyrosine phosphorylation of Syntaxin4 and Munc18c on GLUT4 trafficking

Author

Al Tobi, Mohammed Nasser Rashid and Al Tobi, Mohammed Nasser Rashid

Abstract

Glucose homeostasis is regulated by the opposing actions of insulin and glucagon; insulin facilitates rapid glucose uptake from the blood stream to muscle and adipose cells. These tissues express the facilitative glucose transporter (GLUT4), which in response to insulin is translocated from intracellular compartments to the plasma membrane (PM) allowing glucose entry to cells. GLUT4 undergoes a complex intracellular trafficking itinerary, including recycling to and from the PM, but in the absence of insulin is mainly stored in GLUT4 storage vesicles (GSVs). When insulin binds its receptor, a complicated signalling cascade is initiated which results in the tethering, docking and fusion of GSVs to the PM. Fusion of the GSVs with the plasma membrane is mediated by SNARE proteins. The formation of a SNARE complex composed of Syntaxin4 (Sx4) and SNAP23 localised to the PM and VAMP2 on GSVs is a key event; the formation of this complex is in turn regulated by the Sec1/Munc18 protein, Munc18c. It has been shown that insulin stimulation leads to phosphorylation of Sx4 at two sites (Y115 and Y251) and Munc18c at Y521. The stoichiometry and order of phosphorylation are not yet known, and the biological consequences of this action to be uncovered. Therefore, the current study sought to ascertain the functional consequences of SNARE protein phosphorylation on GLUT4 trafficking. The approaches used include in vitro assessment of recombinant SNARE proteins and studies in vivo using 3T3-L1 adipocytes. The results of this study confirmed that tyrosine 115 and 251 of syntaxin4 are phosphorylated in response to insulin in 3T3-L1 adipocytes; however, phosphorylation of Munc18c was ambiguous. Subsequently, phosphomimetic recombinant SNARE proteins were expressed and ternary SNARE complex formation was successfully recapitulated in vitro and the complex found to be SDS and heat resistant. Phosphomimetic syntaxin4 mutants showed increased formation of SNARE complexes, notably double phos

18. Consequences of tyrosine phosphorylation of Syntaxin4 and Munc18c on GLUT4 trafficking

Author

Al Tobi, Mohammed Nasser Rashid and Al Tobi, Mohammed Nasser Rashid

Abstract

Glucose homeostasis is regulated by the opposing actions of insulin and glucagon; insulin facilitates rapid glucose uptake from the blood stream to muscle and adipose cells. These tissues express the facilitative glucose transporter (GLUT4), which in response to insulin is translocated from intracellular compartments to the plasma membrane (PM) allowing glucose entry to cells. GLUT4 undergoes a complex intracellular trafficking itinerary, including recycling to and from the PM, but in the absence of insulin is mainly stored in GLUT4 storage vesicles (GSVs). When insulin binds its receptor, a complicated signalling cascade is initiated which results in the tethering, docking and fusion of GSVs to the PM. Fusion of the GSVs with the plasma membrane is mediated by SNARE proteins. The formation of a SNARE complex composed of Syntaxin4 (Sx4) and SNAP23 localised to the PM and VAMP2 on GSVs is a key event; the formation of this complex is in turn regulated by the Sec1/Munc18 protein, Munc18c. It has been shown that insulin stimulation leads to phosphorylation of Sx4 at two sites (Y115 and Y251) and Munc18c at Y521. The stoichiometry and order of phosphorylation are not yet known, and the biological consequences of this action to be uncovered. Therefore, the current study sought to ascertain the functional consequences of SNARE protein phosphorylation on GLUT4 trafficking. The approaches used include in vitro assessment of recombinant SNARE proteins and studies in vivo using 3T3-L1 adipocytes. The results of this study confirmed that tyrosine 115 and 251 of syntaxin4 are phosphorylated in response to insulin in 3T3-L1 adipocytes; however, phosphorylation of Munc18c was ambiguous. Subsequently, phosphomimetic recombinant SNARE proteins were expressed and ternary SNARE complex formation was successfully recapitulated in vitro and the complex found to be SDS and heat resistant. Phosphomimetic syntaxin4 mutants showed increased formation of SNARE complexes, notably double phos

19. Consequences of tyrosine phosphorylation of Syntaxin4 and Munc18c on GLUT4 trafficking

Author

Al Tobi, Mohammed Nasser Rashid and Al Tobi, Mohammed Nasser Rashid

Abstract

Glucose homeostasis is regulated by the opposing actions of insulin and glucagon; insulin facilitates rapid glucose uptake from the blood stream to muscle and adipose cells. These tissues express the facilitative glucose transporter (GLUT4), which in response to insulin is translocated from intracellular compartments to the plasma membrane (PM) allowing glucose entry to cells. GLUT4 undergoes a complex intracellular trafficking itinerary, including recycling to and from the PM, but in the absence of insulin is mainly stored in GLUT4 storage vesicles (GSVs). When insulin binds its receptor, a complicated signalling cascade is initiated which results in the tethering, docking and fusion of GSVs to the PM. Fusion of the GSVs with the plasma membrane is mediated by SNARE proteins. The formation of a SNARE complex composed of Syntaxin4 (Sx4) and SNAP23 localised to the PM and VAMP2 on GSVs is a key event; the formation of this complex is in turn regulated by the Sec1/Munc18 protein, Munc18c. It has been shown that insulin stimulation leads to phosphorylation of Sx4 at two sites (Y115 and Y251) and Munc18c at Y521. The stoichiometry and order of phosphorylation are not yet known, and the biological consequences of this action to be uncovered. Therefore, the current study sought to ascertain the functional consequences of SNARE protein phosphorylation on GLUT4 trafficking. The approaches used include in vitro assessment of recombinant SNARE proteins and studies in vivo using 3T3-L1 adipocytes. The results of this study confirmed that tyrosine 115 and 251 of syntaxin4 are phosphorylated in response to insulin in 3T3-L1 adipocytes; however, phosphorylation of Munc18c was ambiguous. Subsequently, phosphomimetic recombinant SNARE proteins were expressed and ternary SNARE complex formation was successfully recapitulated in vitro and the complex found to be SDS and heat resistant. Phosphomimetic syntaxin4 mutants showed increased formation of SNARE complexes, notably double phos

20. A Novel Splice-site Allelic Variant is Responsible for Wilson Disease in an Omani Family.

Author

Al-Tobi M, Kashoob M, Joshi S, and Bayoumi R

Abstract

Objectives: The objective of this study was to characterise Wilson's Disease (WD) [OMIM 277900] genetically and test for allelic variants in the copper transport gene (ATPase, Cu(++) transporting, beta polypeptide, ATP7B) responsible for the disease in an Omani family., Methods: Three index patients from an Omani family had been previously diagnosed with WD. All three patients suffered neurological symptoms and signs. Forty-six relatives in the family were screened for WD. Eleven more individuals were positive, but asymptomatic., Results: Thirteen non-disease-causing allelic gene variants, described previously, were identified in the ATP7B gene from 46 family members. A putative novel disease-causing splice-site variant (c.2866-2A>G), which has not been reported previously, was detected in this family. It is located upstream of exon 13 which encodes part of transmembrane copper channel (Ch/Tm6). Reverse transcription polymerase chain reaction was used to amplify a complementary DNA (cDNA) fragment containing exons 12, 13 and 14. Exon 13 was entirely skipped from the transcript which probably would result in a defective ATP7B protein., Conclusion: A new ATP7B splice-site allelic variant, found among the 14 WD patients segregated with the disease in a recessive manner, suggests it is a disease-causing variant.

Published
2011

Catalog

Books, media, physical & digital resources
See catalog results