Indiana University-Purdue University Indianapolis (IUPUI) / Diabetes mellitus is a complex metabolic disease that currently affects an estimated 422 million people worldwide, with incidence rates rising annually. Type 1 diabetes (T1D) accounts for 5-10% of these cases. Its complications remain a major cause of global deaths. T1D is characterized by autoimmune destruction of β-cell mass. Efforts to preserve and protect β-cell mass in the preclinical stages of T1D are limited by few blood-borne biomarkers of β-cell destruction. In healthy β-cells, insulin secretion requires soluble n-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) complexes and associated accessory regulatory proteins to promote the docking and fusion of insulin vesicles at the plasma membrane. Two target membrane (t)-SNARE proteins, Syntaxin 1/4 and SNAP25/23, and one vesicle-associated (v)-SNARE protein, VAMP2, constitute the SNARE core complex. SNARE complex assembly is also facilitated by the regulatory protein, Double C2-domain protein β (DOC2B). I hypothesized that DOC2B deficiency may underlie β-cell susceptibility to T1D damage; conversely , overexpression of DOC2B may protect β-cell mass. Indeed, with regard to DOC2B abundance, my studies show reduced levels of DOC2B in platelets and islets of prediabetic rodents and new-onset T1D humans. Remarkably, clinical islet transplantation in T1D humans restores platelet DOC2B levels, indicating a correlation With regard to protection/functional effects, DOC2B deficiency enhances susceptibility to T1D in mice, while overexpression of DOC2B selectively in β-cells protects mice from chemically induced T1D; this correlates with preservation of functional β-cell mass. Mechanistically, overexpression of DOC2B and the DOC2B peptide, C2AB, protects clonal β-cell against cytokine or thapsigargin-induced apoptosis and reduces ER stress; this is dependent on C2AB’s calcium binding capacity. C2AB is sufficient to enhance glucose stimulated insulin secretion (GSIS) and SNARE activation in clonal β-cells to the same extent as full-length DOC2B. In summary, these studies identify DOC2B as a potential biomarker and novel therapeutic target for prevention/management of T1D.

The Type VII secretion system (T7SS) is linked to virulence and long-term pathogenesis in a broad range of Gram-positive bacteria, including the human commensal and pathogen Staphylococcus aureus. The Type VIIb secretion system (T7SSb) is responsible for the export of small toxic proteins, which induce antibacterial immune responses and mediate bacterial persistence in the host. In addition, it is also involved in bacterial competition. The T7SSb requires several proteins to build up the secretion machinery. This work focuses on the structural and functional investigation of the motor ATPase EssC and the putative pore forming, multi-pass membrane component EsaA. Both proteins are indispensable for substrate secretion. EssC belongs to the FtsK/SpoIIIE ATPase family and is conserved among the T7SSs. It contains three C-terminal, cytosolic ATPase domains, designated as EssC- D1, -D2 and -D3, whereby EssC-D3 is the most distal one. In this thesis, I am presenting the crystal structure of the EssC-D3 at 1.7 Å resolution. As the deletion of EssC-D3 abrogates substrate export, I have demonstrated that this domain comprises a hydrophobic, surface-exposed pocket, which is required for substrate secretion. More specifically, I have identified two amino acids involved in the secretion process. In addition, my results indicate that not only EssC-D3 is important for substrate interaction but also EssC-D2 and/or EssC-D1. Unlike in the related Yuk T7SSb of Bacillus subtilis, the ATPase activity of D3 domain contributes to substrate secretion. Mutation of the modified Walker B motif in EssC-D3 diminishes substrate secretion completely. The membrane protein EsaA encompasses an extracellular segment spanning through the cell wall of S. aureus. I was able to reveal that this part folds into a stable domain, which was crystallized and diffracted up to 4 Å. The first attempts to dissolve the structure failed due to a lack of homologues structures. Therefore, crystals for single-wavelength anomalous dispersion, containing selenomethionyl-substitutes, were produced and the structure solution is still in progress. Preliminary experiments addressing the function of the extracellular domain indicate an important role in substrate secretion and bacterial competition. / Das Typ VII Sekretionssystem (T7SS) ist wichtig für Virulenz und Langzeit- Pathogenität von Gram-positiven Bakterien. Zu diesen gehört auch Staphylococcus aureus, bekannt als Kommensal und Pathogen im Menschen. Das Typ VIIb Sekretionssystem (T7SSb) exportiert kleine, toxische Proteine, die antibakterielle Immunantworten auslösen und für bakterielle Persistenz verantwortlich sind. Außerdem ist es an dem Konkurrenzkampf zwischen Bakterien beteiligt. Das System benötigt verschiedene Komponenten, um eine Sekretion zu ermöglichen. Diese Doktorarbeit konzentriert sich auf zwei dieser Proteine, die ATPase EssC und das Membranprotein EsaA. Beide Komponenten sind unentbehrlich für eine vollständige Funktionalität. EssC gehört zu der Familie der FtsK/SpoIIIE ATPasen und ist evolutionär in allen T7SSs erhalten. EssC besitzt drei C-terminale, zytosolische ATPase Domänen, bezeichnet als EssC-D1, -D2 und D3, wobei EssC-D3 C-terminal gelegen ist. In dieser Arbeit präsentiere ich die Kristallstruktur der ATPase Domäne EssC-D3, aufgelöst bis zu 1.7 Å. Die Domäne ist unabdingbar für die Sekretion. Durch die Strukturauflösung wurde eine hydrophobe, Oberflächen-exponierte Substrat- Bindetasche bestimmt, die eine essenzielle Rolle für den Export der toxischen Substrate einnimmt. Durch dieses Projekt konnten zwei Aminosäuren in dieser Tasche bestimmt werden, die für den Prozess der Substratsekretion wichtig sind. Weiterhin wurde bewiesen, dass nicht nur EssC-D3, sondern auch die ATPase Domäne EssC-D2 und/oder EssC-D1 mit den Substraten interagieren kann. Im Gegensatz zu dem verwandten T7SSb in Bacillus subtilis, verfügt EssC-D3 über ATPase Aktivität und ermöglicht dadurch den Substratexport. Das Membranprotein EsaA besitzt einen extrazellulären Abschnitt, der sich durch die Zellwand von S. aureus erstreckt. Dieser extrazelluläre Part besteht aus einer stabilen Domäne, welche kristallisiert werden konnte und bis zu 4 Å diffraktiert. Aufgrund von fehlenden homologen Strukturen konnte die Struktur der Domäne noch nicht bestimmt werden. Für die Phasenbestimmung, die wichtig für die Strukturauflösung ist, wurden Kristalle mit Selenomethionyl-Substituten hergestellt. Die Strukturauflösung ist noch nicht beendet. Erste Experimente bezüglich der extrazellulären Domäne zeigen, dass diese ebenfalls wichtig für die Substratsekretion und zusätzlich am Konkurrenzkampf zwischen Bakterien beteiligt ist.

No description available.

No description available.

In the global fight against antibiotic resistance, the need for alternatives is more pressing than ever. Antimicrobial peptides (AMPs), short oligopeptides usually produced as part of the immune system of a host, have shown great promise against resistant bacteria, biofilms and even cancer cells. Engineering AMPs that are both specific to a set of bacteria and stable is among the main challenges of the field. Herein, we propose two separate tools to support these efforts. The first one is an AMP SECretion system based in E. coli, dubbed AMPSEC, that can be used to produce active AMPs with specific targets (i.e., gram-positive bacteria or any specific specie). This recombinant protein system uses surface display technologies coupled with specific protease activity to express, export, and release functional AMPs that could readily affect neighbouring target bacteria. The AMPSEC would be ideal to screen AMP libraries, removing the need for purification or chemical synthesis in order to observe toxicity. It could also be used for AMP production, where the secreted AMPs would be purified from the growth medium by HPLC. Finally, if the recombinant system is inserted in a probiotic host, it might even be useful to deliver AMPs in the gut to treat dysbiosis. Herein, we explored six surface display apparatuses for their applicability for AMPSEC and found three out of the six being fully functional in transporting the cargo although the cleaving activity needs to be coordinated better with its localization at the outer membrane. A robust proof-of-concept workflow has also been established and used to evaluate the performance of those six display apparatuses. The second is a bioinformatics approach to highlighting the relationship between the primary structure and the microbial target specificity of AMPs. Our method first clusters sequences from the DRAMP AMP repository using the Linclust algorithm. De novo motif discovery tools can then extract AMP sequence motifs relating to target specificity. These motifs could guide randomized sequence AMP library creation and decrease the number of inactive sequences generated. Clustering AMPs, however, proved to be rather challenging due to the large sequence length variation in the databases, the small sample size and their overall short lengths. It would then be necessary to design an algorithm suited to handle this specific kind of proteomics dataset. A library eventually created using the discovered motifs could then be used with AMPSEC. Combined, these two tools will further improve our ability to design stable AMPs targeting specific bacteria.

Insect haemolymph typically contains very high levels of free amino acids 50 - 100 times that which is normal for mammalian plasma. This study examines the modulatory effects of amino acids on fluid secretion and ion transport by isolated MTs of Rhodnius prolixus and Drosophila melanogaster. The results show that the secretion rates of isolated Malpighian tubules of both Rhodnius and Drosophila are modulated by the presence of specific amino acids in the bathing saline. Some amino acids are stimulatory, some are inhibitory and others have little or no effect. Glutamine appears to be particularly important as a stimulant of fluid secretion. As well, secreted fluid pH and Na+ concentration increase and K+ concentration decreases in response to glutamine. Amino acids do not appear to be important as metabolites in Rhodnius tubules, nor do they act to draw significant amounts of water into the lumen by osmosis. Significant stimulation of fluid secretion can be achieved by physiological levels of particular amino acids, whereas those amino acids that inhibit fluid secretion only do so at concentrations much above those at which they occur naturally in the haemolymph. Amino acids are known to be compatible osmolytes and may be acting to maintain cell homeostasis and thus to sustain fluid secretion. The passive movement of amino acids may result in cell volume changes, and some form of osmosensor is may be coupled to activation of specific kinases to produce the observed increases in fluid secretion. The effects of several kinase inhibitors were therefore examined. The glutamine dependent increase in MT fluid secretion is blocked by two inhibitors of the stress activated protein kinase (SAPK) pathway, SP600125 and dicumoral. Inhibitors of other kinases (PKA, PKC, PKG, PI-3, p38, ERK and MEK), did not block glutamine’s effects on fluid secretion rate. Alterations in cytoskeletal structure appear not to be required because cytoskeletal disrupting agents did not block the glutamine dependent increase in fluid secretion, nor was the increase dependent upon protein synthesis. Results of this study are the first to suggest a role for the SAPK pathway in the control of fluid secretion rates by insect Malpighian tubules. / Thesis / Master of Science (MS)

<p>Chlamydia trachomatis, the causative agent of trachoma and sexually transmitted infections, employs a type III secretion (T3S) system to deliver effector proteins into host epithelial cells to establish a replicative vacuole. Although the temporal manner in which effectors are secreted is important for the proper manipulation of host cell functions, the mechanism remains a mystery. In this study, we provide several lines of evidence that T3S chaperones may impart coherence to effector secretion. In addition, we identified a new early T3S effector in Chlamydia. Aside from the phosphoprotein TARP, a Chlamydia effector that promotes actin re-arrangements, very few factors mediating bacterial entry and early inclusion establishment have been characterized. By defining proteins that associate with the three most abundant T3S chaperones, Slc1, Scc2 and Mcsc in invasive C. trachomatis elementary bodies (EB) by immunoprecipitation coupled with mass spectrometry, we identified Ct875, a new Slc1 client protein and T3S effector, which we renamed TepP (Translocated early phosphoprotein). We provide evidence that T3S effectors form stable complexes with Scl1 in vitro and that Slc1 enhances their T3S-dependent secretion in a heterologous Yersinia T3S system. We demonstrate that TepP is translocated early during bacterial entry into epithelial cells and is phosphorylated at tyrosine residues by host kinases. However, TepP phosphorylation occurs later than TARP, which together with the finding that Slc1 preferentially engages TARP in EBs leads us to postulate that these effectors are translocated into the host cell at different stages during C. trachomatis invasion. TepP co-immunoprecipitated with the scaffolding proteins CrkI-II during infection and Crk was recruited to nascent inclusions. Importantly, C. trachomatis mutants lacking TepP failed to recruit CrkI-II to inclusions, providing genetic confirmation of a direct role for this effector in the recruitment of a host factor. Finally, endocervical epithelial cells infected with a tepP mutant showed altered expression of a subset of genes associated with innate immune responses and lack of C. trachomatis-induced morphological changes. We propose a model wherein TepP acts downstream of TARP to recruit scaffolding proteins at entry sites to initiate and amplify signaling cascades important for the regulation of innate immune responses to Chlamydia.</p> / Dissertation

Introduction: MSCs are multipotent progenitor cells that can differentiate into various cell lineages, such as osteoblasts, chondrocytes and adipocytes. MSCs synthesize abundant secretion factors to extracellular matrix which contain a variety of growth factors, cytokines and microRNAs. Secretion factors could stimulate the regeneration and differentiation of surrounding cells, but their underlying mechanism still remains elusive. We hypothesized that secretion factors from different tissues derived MSCs had potential to promote MSCs differentiation and musculoskeletal tissue regeneration. We also suggested that microRNAs played an essential role in the effects of secretion factors. In present study, we investigated the effects of secretion factors obtained from different tissues derived MSCs (umbilical cord, dental pulp, gingiva and adipose tissue) on multi-differentiation potentials of MSCs, including osteogenesis, chondrogenesis, tenogenesis, neurogenesis and adipogenesis. Moreover, we illustrated the effects of umbilical cord derived MSC (UCMSC) secretion on bone, cartilage and tendon tissue repair. We further revealed that microRNAs may impact the effect of secretion factors on MSCs osteogenic differentiation. / Methods: Human bone marrow MSCs (hBMSCs) were incubated with various differentiation induction media. Secretion factors were used as supplement. Different animal models of tissue repair (bone, cartilage and tendon) were employed for study of the effects of secretion factors on tissue healing. miRNA microarray was performed to find the potential effective miRNAs in secretion factors. Real time qRT-PCR, microCT, mechanical test, immunohistological analysis and various staining methods were employed as outcome measurements. / Results: We found that both UCMSC and dental pulp derived MCS secretion could initiate osteogenic differentiation of hBMSCs without osteogenic induction medium. UCMSC secretion had positive effect on chondrogenic and tenogenic differentiation of MSCs and inhibitory effect on adipogenesis of hBMSCs. Our results showed that UCMSC secretion in HA/TCP scaffolds with hBMSCs promoted ectopic bone formation in nude mice. UCMSC secretion with rat BMSCs in hyaluronic hydrogel significantly enhanced the bone repair of rat calvarial bone critical defect. To reveal the underlying mechanism, secretion factors were analyzed by miRNA microarray. Among the differentially expressed microRNAs, we found miR-1237 could promote osteogenesis while miR-3676 could inhibit osteogenic differentiation of MSCs. / Conclusions: This study indicated that among secretion factors from MSCs form four types tissues, UCMSC secretion could initiate osteogenesis of MSCs and promote bone repair. We also demonstrated that microRNAs from secretion had impact on osteogenic differentiation of MSCs. Our study showed clinical potential of UCMSC secretion in bone regeneration, and more research are needed for optimizing the preparation and delivery of the MSCs secretive factors, as well as to understand their mechanisms of action. / 前言：間充質幹細胞是具有強大分化潛能的始祖細胞。間充質幹細胞可以分化為多種細胞系，例如成骨細胞，軟骨細胞和脂肪細胞。間充質幹細胞合成并釋放大量分泌素到細胞外基質中。這些分泌素包括多種生長因子，細胞因子和微小核糖核酸。分泌素能夠刺激周圍細胞的再生和分化，但是分泌素的作用機理還不是很清楚。我們認為，不同組織來源的間充質幹細胞分泌素有可能會促進間充質幹細胞的多系分化和骨骼肌肉組織的再生，並且微小核糖核酸在分泌素的效應中發揮了重要作用。我們首先研究了臍帶，牙髓，牙齦和脂肪來源的間充質幹細胞分泌素對于間充質幹細胞的分化能力的作用。我們還對臍帶幹細胞分泌素在骨，軟骨和肌腱修復的效果做了進一步的研究。另外，我們還發現分泌素中的微小核糖核酸在間充質幹細胞的成骨分化方面有一定的效果。 / 方法：我們用人間充質幹細胞來進行誘導分化實驗。臍帶，牙髓，牙齦和脂肪來源的間充質幹細胞的分泌素用於細胞培養基的補充。在體內實驗中我們用了不同的動物模型，把填充物和分泌素一起種植在動物體內。我們利用微小核糖核酸陣列技術來檢測分泌素中的有效微小核糖核酸。我們使用了定量聚合酶鏈反應技術，微型計算機斷層掃描成像，力學測試，免疫組織分析和多種染色方法。 / 結果：我們發現臍帶和牙髓間充質幹細胞分泌素可以在沒有成骨誘導培養基的情況下啟動骨髓間充質幹細胞的成骨分化。臍帶間充質幹細胞對成軟骨和成肌腱分化起到積極作用，而且可以抑制脂肪分化。我們發現在羥基磷灰石/磷酸三鈣材料中，臍帶間充質幹細胞分泌素與人骨髓間充質幹細胞可以共同促進裸鼠的異位成骨。臍帶間充質幹細胞分泌素與鼠骨髓間充質幹細胞一起用於透明質酸水凝膠中能夠加快大鼠頭骨缺損的修復。為了揭示分泌素的作用機理，我們用微小核糖核酸陣列技術來檢測分泌素。在表達不同的微小核糖核酸之中，我們發現miR-1237可以促進間骨髓間充質幹細胞的成骨分化，而miR-3676能夠抑制骨髓間充質幹細胞成骨分化。 / 結論：本研究表明，在四種不同來源的分泌素中，臍帶間充質幹細胞分泌素可以啟動骨髓間充質幹細胞的成骨分化，同時加快骨組織修復。我們發現微小核糖核酸在分泌素的促進間骨髓間充質幹細胞成骨分化的效果中發揮了一定的作用。我們的研究表明，使用臍帶間充質幹細胞分泌素修復骨組織具有廣泛的臨床應用前景。間充質幹細胞分泌素的生產，使用過程和作用機理還有待于進一步的優化和研究。 / Wang, Kuixing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 131-147). / Abstracts also in Chinese. / Title from PDF title page (viewed on 01, November, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

by Psyche, Sui-Ki Fong. / Thesis submitted in: December 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 129-135). / Abstract also in Chinese. / Abstract in Chinese --- p.1 / Abstract in English --- p.2 / Chapter Chapter I. --- Introduction --- p.4 / Chapter I.1. --- Structure and functions of the uterus --- p.4 / Chapter I.1.1. --- Uterus: Gross structure and functions --- p.4 / Chapter I.1.2. --- Uterine wall: functional layers --- p.6 / Chapter a. --- Myometrium --- p.6 / Chapter b. --- Endometrium --- p.6 / Chapter I.1.3. --- Uterine functions : regulatory systems --- p.10 / Chapter a. --- Nervous regulation --- p.10 / Chapter b. --- Hormonal regulation --- p.11 / Chapter I.1.4. --- Uterotrophic agents : selected examples --- p.12 / Chapter a. --- Adrenaline and noradrenaline --- p.12 / Chapter b. --- Prostaglandin E2 and F2α --- p.15 / Chapter I.2. --- Endometrial epithelium and uterine fluid composition --- p.19 / Chapter I.2.1. --- Uterine fluid composition --- p.19 / Chapter I.2.2. --- Regulation of uterine fluid volume and composition --- p.19 / Chapter I.2.3. --- Role of endometrial epithelium in the regulation of uterine fluid composition --- p.20 / Chapter I.3. --- Pioneering works on ion transport across the endometrium --- p.21 / Chapter I.4. --- Objectives of study --- p.23 / Chapter Chapter II --- Materials and Methods --- p.24 / Chapter II.1. --- Materials --- p.24 / Chapter II.1.1. --- Culture media and enzyme --- p.24 / Chapter II 1.2. --- Drugs --- p.24 / Chapter II 1.3. --- Chemicals --- p.25 / Chapter II 1.4. --- Animals --- p.25 / Chapter II.2. --- Methods --- p.25 / Chapter II.2.1. --- Preparation of permeable support for cell culture --- p.25 / Chapter II.2.2. --- Preparation of culture medium for cell culture --- p.26 / Chapter II.2.3. --- Cell isolation and culture --- p.28 / Chapter II.2.4. --- Preparation of electrodes --- p.29 / Chapter II.2.5. --- Preparation of solutions --- p.29 / Chapter II.2.6. --- The short-circuit current technique --- p.31 / Chapter a. --- Experimental setup --- p.32 / Chapter b. --- Transepithelial conductance and resistance measurements --- p.37 / Chapter c. --- Experimental procedure --- p.37 / Chapter II.2.7. --- Statistics --- p.38 / Chapter Chapter III. --- Results --- p.39 / Chapter III.1. --- Electrogenic ion transport across the cultured mouse endometrial epithelium --- p.39 / Chapter III.2. --- Stimulation of anion secretion by β-adrenoceptors --- p.54 / Chapter III.3. --- Regulation of anion secretion by prostaglandin E2 --- p.78 / Chapter III.4. --- Cellular mechanisms of adrenaline-stimulated anion secretion --- p.98 / Chapter Chapter IV. --- General Discussion --- p.123 / Chapter Chapter V. --- Reference --- p.129

The purpose of this study was to determine the effects of high intensity eccentric muscle damage on plasma creatine kinase and plasma malondialdehyde. Twelve subjects, who served as their own control, performed 10 sets of eccentric knee extensions at a 10 RM intensity with their dominant leg. The subjects lowered the resistance in slow controlled manner to a three count of a metronome set at one beat per second. The resistance was set at an intensity equal to 120% of the subject's concentric 1RM. Creatine kinase and malondialdehyde were measured pre-exercise and at 24, 48, 72, 96 and 120 hours post-exercise. Results (p<_ .05) showed a significant increase in both creatine kinase and malondialdehyde compared to baseline. Creatine kinase showed significant increases through 120 hours post-exercise, and peaked at 96 hours post-exercise. Malondialdehyde showed significant increases through 72 post-exercise and peaked at 24 hours postexercise. It appears that a single bout, of high intensity, eccentric exercise can cause significant increases in creatine kinase and malondialdehyde. / Department of Speech Pathology & Audiology