Protein quality control in the mammalian endoplasmic reticulum

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2011.Cataloged from PDF version of thesis. "February, 2011."Includes bibliographical references.Quality control is an important part of protein biogenesis. Aberrant proteins must be destroyed before they aggregate and cause deleterious effects. Failure to do so can result in cell death or malfunction and, ultimately, disease. Quality control involves the recognition of misfolded proteins and their degradation. For secretory and membrane proteins, folding occurs in the endoplasmic reticulum (ER), but degradation is performed by the cytosolic proteasome. Thus, quality control in the secretory system includes the dislocation of misfolded proteins from the ER to the cytoplasm. ER proteins that fail to fold correctly are identified and directed to the membrane-associated ER quality control machinery. They are then moved across the ER membrane, tagged with ubiquitin, and extracted from the membrane and complex. Finally, the dislocation substrate is taken to the proteasome where it is degraded. Many proteins constituting the mammalian quality control machinery have been identified. Several different dislocation complexes work in parallel to clear misfolded proteins from the ER and they are distinguished by their E3 ubiquitin ligase. This thesis describes the identification and characterization of several previously unknown members of the HRD1-associated ER quality control complex. The newly-identified proteins are osteosarcoma amplified-9 (OS9), UBX domain containing-8 (UBXD8), Ubiquitinconjugating enzyme-6e (UBC6e), and ancient ubiquitous protein-i (AUP1). Each of these proteins participates in different steps of ER quality control. OS9 directs misfolded soluble glycoproteins to the dislocation complex. The mannose-6- phosphate homology domain of OS9 is involved in the recognition of glycans on the misfolded protein. UBXD8 recruits p97, the AAA+ ATPase responsible for membrane extraction of dislocated proteins, to the ER using its UBX domain. UBC6e is a membrane-anchored E2 ubiquitin conjugating enzyme. AUP1 recruits a second E2, soluble UBE2G2. Additionally, AUPI regulates substrate mono- and poly-ubiquitylation. AUPI is also necessary for lipid droplet formation. Lipid droplets are cytoplasmic organelles that store neutral lipids. Based on the data that AUPI depletion affects both ER quality control and lipid droplet formation and that pharmacological inhibition of lipid droplet formation perturbs dislocation, we propose that lipid droplet formation may also play a role in ER protein quality control.by Elizabeth J. Klemm.Ph.D

Suicidal asphyxiation by using helium – two case reports

Helium is one of inert gases causing physical asphyxiation, whose excess content in the breathing atmosphere reduces the partial pressure of oxygen and may be fatal after short-term exposure. When breathing a mixture of an inert gas (helium, nitrogen, argon) with a small amount of oxygen, with the possibility of exhaling carbon dioxide, no warning signs characteristic of suffocation are perceived by the subject. Freedom from discomfort and pain, effectiveness, rapid effect and relatively easy availability of required accessories have resulted in the use of inert gases for suicidal purposes. The paper reports two cases of suicide committed by using a special kit consisting of the so-called “suicide bag” (or “exit bag”) filled with helium supplied through a plastic tube. In both cases, examination of the sites where the corpses were found and analysis of collected material allowed to establish that before their death the subjects had searched the Internet for instructions on how to commit suicide using helium. Due to the advanced putrefaction process, the autopsies failed to determine the causes of their death unequivocally. However, the circumstances surrounding the deaths suggested rapid asphyxiation as a result of oxygen deficiency in the breathing mixture. Since in cases of the type discussed here the cause of death cannot generally be established by autopsy, knowledge of the circumstances of disclosure of the corpse, as well as examination of the cadaver and the death scene is of utmost importance

Complications of aesthetic medicine procedures: five case studies

The paper presents the cases of five patients who developed complications after aesthetic medicine procedures. Four of the cases involved women who reported to the Department of Forensic Medicine, Medical University of Lodz, for a description and legal qualification of bodily injuries suffered as a result of aesthetic medicine procedures, whereas one was related to the assessment of accuracy of medical management at the request of the prosecutor handling the case. The reported cases concerned acid exfoliation treatments, photoepilation and cryotherapy. The authors attempt to discuss the most common complications that may occur after aesthetic medicine procedures, and measures to avoid them

Chylothorax as a rare complication of acute pancreatitis in a 25-year-old woman after cesarean section

The paper presents the case of a 25-year-old woman who underwent cesarean section for gynecological indications in the 37th week of her second pregnancy. The perioperative course was uncomplicated, but one day later the general condition of the patient suddenly deteriorated: she developed respiratory disorders requiring intubation and treatment in an intensive care unit. On the 6th day after the surgery, the patient was diagnosed with acute pancreatitis. Appropriate conservative treatment was instituted, resulting in a gradual improvement of her condition. On the 13th postoperative day, a cardiac arrest in asystole occurred, with no response to the undertaken resuscitation procedures. An autopsy performed in the Department of Forensic Medicine in Łódź revealed, among other findings, acute pancreatitis with enzymatic necrosis of the adipose tissue, a significant accumulation of lymph in both pleural cavities, and pulmonary atelectasis. As demonstrated by the analysis of the case, chylothorax had most probably developed in the course of acute pancreatitis which was a complication of the cesarean section. Consequently, the prosecutor opened an investigation into the case under Article 155 of the Polish Penal Code to assess the appropriateness of medical management. The medico-legal opinion was issued by experts from outside the Department of Forensic Medicine in Łódź. In their view, the medical management of the patient was correct

Badania oddziaływań pomiędzy diklofenakiem i surowiczą albuminą wołową (BSA)

Investigation of the interactions between diclofenac and BSA was performed using UV-Vis absorption and fluorescence methods. There was a quenching effect found between these two molecules in the fluorescence measurement methods; steady-state and time-resolved. The fluorescence decay time enables to determine the quenching mechanism and thus conclude that the complex is formed in ground-state but also collisional quenching - when the excited-state fluorophore of BSA is deactivated - occurs. Computer modeling was applied to observe and optimize the formation of the complex between N-acetyl-L-tryptophamide and diclofenac.W pracy zbadano oddziaływania pomiędzy diklofenakiem i surowiczą albuminą wołową przy użyciu metod spektroskopii absorpcyjnej UV-Vis oraz metod fluorescencyjnych. Wyniki wskazują na istnienie interakcji pomiędzy cząsteczkami zarówno w stanie wzbudzonym (wygaszanie dynamiczne) jak i podstawowym (powstanie niefluoryzującego kompleksu). Za pomocą modelowania molekularnego zdołano zoptymalizować kompleks pomiędzy diklofenakiem a N-acetylo-L-tryptofanamidem