Defining the functions and mechanisms of mRNA targeting to the mitotic apparatus

La localisation des ARNm dans différents compartiments subcellulaires est conservée dans un large éventail d'espèces et de divers types cellulaires. Le trafic est médié par l'interaction entre les protéines de liaison à l'ARN (RBP) et l'ARNm. Les RBP reconnaissent les éléments cis-régulateurs de l'ARNm, également appelés éléments de localisation. Ceux-ci sont définis par leur séquence et/ou leurs caractéristiques structurelles résidant dans la molécule d'ARNm. La localisation des ARNm est essentielle pour la résolution subcellulaire et temporelle. De plus, les ARNm se sont avérés enrichis dans de nombreux compartiments cellulaires, notamment les mitochondries, l'appareil mitotique, et le réticulum endoplasmique. En outre, des études ont démontré que les RBP et les ARNm sont associés aux structures de l'appareil mitotique. Cependant, le rôle que joue la localisation de l'ARNm au cours de la mitose reste largement inexploré. Ma thèse de doctorat vise à comprendre comment le trafic d'ARNm est impliqué lors de la mitose. La première partie de cette thèse porte sur l'interaction post-transcriptionnelle qui se produit entre les deux ARNm, cen et ik2. Les gènes qui se chevauchent sont une caractéristique frappante de la plupart des génomes. En fait, il a été constaté que le chevauchement des séquences génomiques module différents aspects de la régulation des gènes tels que l'empreinte génomique, la transcription, l'édition et la traduction de l'ARN. Cependant, la mesure dans laquelle cette organisation influence les événements réglementaires opérant au niveau post-transcriptionnel reste incertaine. En étudiant les gènes cen et ik2 de Drosophila melanogaster, qui sont transcrits de manière convergente avec des régions 3' non traduites qui se chevauchent, nous avons constaté que la liaison physique de ces gènes est un déterminant clé dans la co-localisation de leurs ARNm aux centrosomes cytoplasmiques. Le ciblage du transcrit ik2 dépend de la présence et de l'association physique avec l'ARNm de cen, qui est le principal moteur de la co-localisation centrosomale. En interrogeant les ensembles de données de séquençage de fractionnement, nous constatons que les ARNm codés par des gènes qui se chevauchent en 3' sont plus souvent co-localisés par rapport aux paires de transcrits aléatoires. Ce travail suggère que les interactions post-transcriptionnelles des ARNm avec des séquences complémentaires peuvent dicter leur destin de localisation dans le cytoplasme. La deuxième partie de cette thèse consiste à étudier le rôle que jouent les RBP au cours de la mitose. Auparavant, les RBP se sont avérés être associés au fuseau et aux centrosomes. Cependant, leur rôle fonctionnel au niveau de ces structures reste à étudier. Grâce à un criblage par imagerie avec plus de 300 anticorps, nous avons identifié 30 RBP localisés dans les structures mitotiques des cellules HeLa. Ensuite, pour évaluer les rôles fonctionnels de ces RBP, nous avons utilisé l'interférence ARN (ARNi) pour évaluer si la fidélité du cycle cellulaire était compromise dans les cellules HeLa et les embryons de Drosophila melanogaster. Fait intéressant, nous avons identifié plusieurs candidats RBP pour lesquels le knockdown perturbe la mitose et la localisation de l'ARNm dans les cellules HeLa. De plus, la perte des orthologues a entraîné des défauts de développement chez l'embryon de mouche. Grâce à ce travail, nous avons démontré que les RBP sont impliquées pour assurer une mitose sans erreur. En résumé, les travaux que j'ai menés mettent en lumière l'implication de la régulation post-transcriptionnelle au cours de la mitose. En définissant les fonctions et le mécanisme de localisation des ARNm en mitose, ce travail permettra de définir de nouvelles voies moléculaires impliquées dans la régulation de la mitose. Puisque la division cellulaire non contrôlée peut mener à des maladies tel le cancer, étudier le contrôle du cycle cellulaire sous cet angle « centré sur l'ARN » peut aider à développer de nouvelles approches thérapeutiques pour trouver des solutions aux problèmes de santé.The localization of mRNAs to different subcellular compartments is conserved in a wide range of species and diverse cell types. Trafficking is mediated by the interaction between RNA binding proteins (RBPs) and mRNA. RBPs recognize mRNA cis regulatory motifs, otherwise known as localization elements. These are defined by their sequence and/or structural features residing within the mRNA molecule. Localization of mRNAs is essential for subcellular and temporal resolution. Furthermore, mRNAs have been found to be enriched in many cellular compartments including the mitochondria, mitotic apparatus, and endoplasmic reticulum. Moreover, studies have demonstrated that RBPs and mRNAs are associated with mitotic apparatus structures. However, the role that mRNA localization plays during mitosis remains largely unexplored. My PhD thesis aims to understand how the trafficking of mRNAs is implicated during mitosis. The first part of this thesis encompasses the post-transcriptional interaction that occurs between the two mRNAs, cen and ik2. Overlapping genes are a striking feature of most genomes. In fact, genomic sequence overlap has been found to modulate different aspects of gene regulation such as genomic imprinting, transcription, RNA editing and translation. However, the extent to which this organization influences regulatory events operating at the post-transcriptional level remains unclear. By studying the cen and ik2 genes of Drosophila melanogaster, which are convergently transcribed with overlapping 3’untranslated regions, we found that the physical linkage of these genes is a key determinant in co-localizing their mRNAs to cytoplasmic centrosomes. Targeting of the ik2 transcript is dependent on the presence and physical association with cen mRNA, which serves as the main driver of centrosomal colocalization. By interrogating global fractionation-sequencing datasets, we find that mRNAs encoded by 3’overlapping genes are more often co-localized as compared to random transcript pairs. This work suggests that post-transcriptional interactions of mRNAs with complementary sequences can dictate their localization fate in the cytoplasm. The second part of this thesis involves investigating the role that RBPs play during mitosis. Previously, RBPs have been found to be associated with the spindle and centrosomes. However, their functional role at these structures was yet to be investigated. Through an imaging screen with >300 antibodies, we identified 30 RBPs localized to mitotic structures in HeLa cells. Then, to assess the functional roles of these RBPs, we used RNA interference (RNAi) to assess whether cell cycle fidelity was compromised in HeLa cells and Drosophila melanogaster embryos. Interestingly, we identified several RBP candidates for which the knockdown disrupted mitosis and mRNA localization in HeLa cells. Furthermore, loss of the orthologs led to developmental defects in the fly embryo. Through this work, we demonstrated that RBPs are involved in ensuring an error-free mitosis. In summary, the work that I have conducted sheds light on the involvement of post-transcriptional regulation during mitosis. By defining the functions and mechanism of mRNA localization in mitosis, this work will help define new molecular pathways involved in mitosis regulation. As uncontrolled cell division can lead to diseases such as cancer, studying cell cycle control from this ‘RNA-centric’ angle may help to develop new therapeutic approaches to find solutions to health problems

CMOS Active Inductor and Its Applications

Electronic industries always drive to add more functionalities to the devices. Tunability and compactness have become thrust parameters for the microelectronic researchers. In wireless communication, capacitor and inductor are the most significant reactive components for frequency selection. Out of these two reactive components, inductor occupies significant size of entire chip area. As a result, any circuit containing passive inductor such as voltage-controlled oscillator (VCO), low-noise amplifier (LNA), filter, and power dividers consume wider chip size. To meet the requirement of microelectronics industries, passive components have been replaced with active ones. In this chapter, passive inductor has been substituted with CMOS based active inductor

DEVELOPMENT AND VALIDATION OF REVERSE-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR SIMULTANEOUS ESTIMATION OF OLANZAPINE AND ARIPIPRAZOLE IN SYNTHETIC MIXTURES

Objective: A simple, rapid, accurate, precise, specific, and sensitive reverse-phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for simultaneous estimation of olanzapine (OLZ) and aripiprazole (APR) in synthetic mixtures. Methods: The stationary phase used for chromatographic separation was Phenomenex C18 column (250 mm × 4.6 mm i.d, particle size 5 μm) and mobile phase used for separation was methanol: Phosphate buffer (pH 3) taken in ratio of 75:25 %v/v. The flow rate was used 1.0 ml/min at room temperature and drugs detected at 240 nm with injection volume 20 μL. Results: The retention time for OLZ and APR was found to be 4.231 and 6.523 min, respectively. The linearity was performed using a concentration range of 0.5–3.0 for both drugs. The correlation coefficient was found to be 0.999 for OLZ and APR. The % purity of both the drug was found to be 98–102%. The proposed RP-HPLC method has been validated, according to International council on harmonization Q2 (B) guidelines. Conclusion: There was no interference of any diluents and excipients in the determination of drugs from synthetic mixture. Hence, the developed method can be used for routine quality control analysis

Effect of Alcohol on Gut-Liver Axis and Adipose Tissue

Adipose tissue comprises of large volumes of biologically functioning fat globule, which employs substantial systemic effect. Adipocytes and adipokines play an active role in autocrine, paracrine, or endocrine metabolic functions. Recent studies demonstrated that the hormonal role of adipocyte and adipose tissue dysfunction contributes to the pathogenesis of alcoholic liver disease (ALD) by the activation of CYP2E1. The gut microbiome and adipose tissue response play a pivotal role in the pathogenesis of ALD. Enteric dysbiosis increases plasma levels of metabolites that activate Kupffer cells. Recent literature suggested that chronic alcohol consumption is also correlated with oxidative stress in adipose tissue, inflammation, and adipocyte cell death, decrease in adiponectin, increase level of leptin and resistin, adipose tissue mass, and insulin resistance that acts on the muscle and liver. Dysbiosis combined with non-nutritional diet has an effect on the luminal metabolism causing immunological changes in the gut that might also contribute to pathogenesis of nonalcoholic fatty liver disease (NAFLD). Understanding the interaction between the altered gut microbiota, diet, environmental factors, and their effects on the gut-liver axis can provide an insight toward the pathogenesis of liver-associated disease

Case Report: Splenic Infarct s/p Sleeve Gastrectomy

A case of splenic infarct s/p sleeve gastrectomy is presented. A 28-year-old female presented with LUQ pain s/p sleeve gastrectomy POD7. CT scan with IV contrast revealed an area of nonenhancement at the superomedial aspect of the spleen consistent with a small splenic infarct. She was transferred out to the hospital under the service of the surgeon who had performed her sleeve gastrectomy. Splenic infarction is a rare post-op complication s/p sleeve gastrectomy. The spleen has dual blood supply via the splenic artery and short gastric arteries making complete infarction rare. It is usually diagnosed via CT with IV contrast. The aim of this case report is to the increase the awareness of splenic infarction as a potential complication s/p bariatric surgery

Visual Cryptography in Biometrics Passport

Every human being is unique in their nature such as traits and physical symptoms so computer science is using the biometric f or perfect identification within large database. Visual cryptography scheme is a cryptographic technique, which allows visual information e.g. printed text, handwritten notes, and picture to be encrypted in such a way that the decryption can be performed by the human visual system, without the aid of computers. Biometric passport is a smart card technology product created by use of biometric data and computer chip f or authenticate identification of citizen of particular country. Current passport has certain shortcoming. In the is method it is proposed to convert scan images of retina, fingerprint and face in secret image and meaningful shares by use of visual cryptography. In this method wi th use of Visual Cryptography three biometrics i.e . retina image, fingerprint image and fa ce image encrypted in two meaningful shares when these two share stacking on one another fingerprint image revealed and that can be verified with on the spot live fingerprint image for perfect identification accuracy

A study of adverse drug reactions to iodinated contrast agents in tertiary care teaching hospital

Background: Contrast agents have long been used for the imaging of anatomic boundaries and to explore normal and abnormal findings in X-ray based imaging technique. These agents are not completely devoid of risk. Adverse effects from administration of contrast media vary from minor physiological disturbance to rare life threatening situation.Methods: A cross-sectional retrospective observational study over one-year duration from 1st August 2015 to 31st July 2016 was conducted at radiology department of a Pandit Deendayal Upadhyay Government Medical College and Teaching hospital, Rajkot, Gujarat. Adverse drug reactions were analyzed to study the nature of reactions caused by iodinated contrast agents. The temporal relationship of time of administration of contrast agents to the occurrence of adverse reaction was analyzed and classified as immediate or delayed type of reaction.Results: Out of 868 patients that were analysed 15 out of 497 male patients and 11 out of 371 female patients developed adverse reaction. Age range of patients that developed reactions was 20-55 years. Most common adverse drug reaction occurred in our study was nausea and vomiting which was treated by parenteral Ondansetron. All the reactions were found to be ‘probable’ in causality as per WHO causality assessment scale and Naranjo’s algorithm.Conclusions: Physicians performing diagnostic or therapeutic procedures with contrast agents must be aware of the risk, preventability & treatment so that reactions can be prevented. Sensitization of physicians is required to increase reporting of adverse drug reactions occurred due to radiocontrast agents

Development and validation of UV Spectrophotometric method for simultaneous estimation of Efonidipine hydrochloride ethanolate and Chlorthalidone in their synthetic mixture

Efonidipine Hydrochloride Ethanolate and Chlorthalidone is used in management of hypertension and under clinical phase 3 study. The development of quality control method is required for accurate analysis of both drugs. Two simple, precise and economical UV spectrophotometric methods have been developed for the simultaneous estimation of Efonidipine Hydrochloride Ethanolate and Chlorthalidone in their synthetic mixture. Method I is simultaneous equation method (Vierodt’s Method), which is based on measurement of absorption at 251 and 227 nm i.e. λmax of Efonidipine Hydrochloride Ethanolate and Chlorthalidone, respectively. Method II is first order derivative was based on the measurement of absorbance of Efonidipine Hydrochloride Ethanolate measure at 283.2 nm (ZCP of Chlorthalidone) and absorbance of Chlorthalidone measure at 250.8 nm (ZCP of Efonidipine Hydrochloride Ethanolate). Linearity was observed in the concentration range of 6.4-38.4 µg.mL-1 for Efonidipine hydrochloride ethanolate and 2-12 µg.mL-1  for Chlorthalidone using methanol as a solvent. The accuracy of methods was assessed by recovery studies and was found to be within range of 98-102% for both the drugs. Precision of the methods was estimated by repeatability and intermediate precision studies. The % RSD values were found to be less than 2, proving methods were precise. Two methods were compared using F- test. The results were validated statistically as per ICH Q2 R1 guideline and were found to be satisfactory

Preparation and characterization of rufinamide HP-β-cyclodextrin complexes prepared by the kneading method for solubility enhancement

ACKNOWLEDGEMENT: The author(s) are thankful to Ramanbhai Patel College of Pharmacy, Gujarat for providing facility to carry out research work.Aims: The present investigation concerns the preparation and characterization of Rufinamide HP-β-cyclodextrin complexes prepared by the kneading method. Material & methods: Rufinamide was procured as a gift sample from Torrent Pharmaceuticals limited. HP-β-cyclodextrin (HP-β-CD) was purchased from Himedia, India. Methanol and Hydrochloric Acid were purchased from S. D. Fine Chem. Pvt. Ltd., India. kneading method was selected to prepare inclusion complexation of Rufinamide. Phase solubility study was performed to check formation of inclusion complex. Prepared complex were characterize by different methods like DSC study, FTIR study, X-RPD study & in-vitro dissolution study Results: It was found that there is a formation of 1:1 inclusion complex between HP-β-CD as stability constant was found to be 221.27 M-1. DSC study, FTIR study had given supporting data for formation of inclusion complex. Amorphous nature of the complex was confirmed from the X-RPD study. Conclusions: From in-vitro dissolution study it was found that 1:1.5 complex showed around 50% drug released in 30 min & more than 70% of Drug release in 60 mins.Objetivos: La presente investigación se refiere a la preparación y caracterización de complejos de rufinamida HP-β-ciclodextrina preparados por el método de amasado. Material y métodos: La rufinamida fue donada por la empresa Torrent Pharmaceuticals limitado. HP-β-ciclodextrina (HP-β-CD) se adquirió de Himedia, India. Metanol y ácido clorhídrico se obtuvieron de SD Fine Chem. SA. Ltd., India. Se utilizó el método de amasado para preparar complejos de inclusión de rufinamida. El estudio de la fase de solubilidad se realizó para comprobar la formación de complejos de inclusión. Los complejos preparados se caracterizaron por diferentes métodos como DSC, FTIR, X-RPD y ensayo de disolución in vitro. Resultados: Se encontró que se producían formación de complejos en la relación 1:1. La constante de estabilidad encontrada fue de 221,27 M-1. Los estudios de DSC, FTIR confirmaron la formación del complejo de inclusión. Mediante X-RPD se confirmó la naturaleza amorfa del complejo. Conclusiones: El estudio de disolución in vitro mostró que la proporción 1:1.5 liberaba alrededor de 50% de fármaco en 30 min y a los 60 minutos se consiguió una liberación del 70%