dc.contributor.advisor | Dihazi, Hassan Prof. Dr. | de |
dc.contributor.author | Bibi, Asima | de |
dc.date.accessioned | 2013-01-14T15:06:41Z | de |
dc.date.available | 2013-01-30T23:51:03Z | de |
dc.date.issued | 2012-11-28 | de |
dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-000D-EF88-D | de |
dc.identifier.uri | http://dx.doi.org/10.53846/goediss-1451 | |
dc.description.abstract | Chronische Nierenerkrankung (CKD, chronic
kidney disease) ist weltweit zu einem großen Gesundheitsproblem
geworden. Das kontinuierliche Fortschreiten der CKD scheint das
Ergebnis der Selbsterhaltung der Mechanismen zu sein, die einer
anfänglichen Schädigung zugrunde liegen. Die Niere, als das
Blutfiltrationsorgan, ist stets toxische Metabolismus-Abfälle,
Wasserüberschuss und Ionen ausgesetzt. Mit dem Ziel, die
molekularen Mechanismen zu verstehen, die eine normal
funktionierende Niere zu einer kranken Niere überführen, wurden
proteomische Analyse von Nierenzellen unter verschiedenen
physiologischen Bedingungen wie osmotischer Stress, oxidativer
Stress und Zytokinbehandlung durchgeführt. Interessanteweise haben
die Daten gezeigt, dass Calreticulin, eine Ca2+-bindendes
Endoplasmatische Reticulum (ER)-Protein, eine starke
Expressionsregulierung aufweist. Innerhalb des ERs, spielt die
Calreticulin eine wichtige Rolle als Chaperon, die zur richtigen
Proteinfaltung beiträgt. Des Weitern kommt der Calreticulin als
Ca2+-bindendes ER Protein, eine wesentliche Rolle bei der
Regulierung der cytososlischen Calciumkonzentration zu. Der Ziel
dieser Studie war es, die mögliche Rolle von Calreticulin in der
Nierenerkrankungen zu studieren wie auch die Mechanismen zu
untersuchen, die dieses Protein mit der Regulierung der Funktion
der Nierenzellen und das Fortschreiten der Nierenschädigung
verbinden. Zur Verwirklichung der Ziele wurden sowohl in-vitro als
auch in vivo Studien durchgeführt. Kapitel 2 der Dissertation
beschäftigt sich mit der in-vitro-Untersuchungen: Kombination der
zweidimensionalen Gelelektrophorese (mit Fluoreszenz gefärbten
Proteine) und Massenspektrometrie, zeigt eine starke
Runterregulierung der Calreticulin-Expression in Nierenzellen unter
osmotischen Stress. Die Expressionsänderung der Calreticulin
korrelierte mit einer kontinuierlichen Steigerung der Konzentration
des freien intrazellulären Ca2+. Andererseits, die Hemmung der
Ca2+-Freisetzung, durch IP3R Antagonisten, verhinderte die
Expressionsänderung der Calreticulin unter Stressbedingungen. Dies
resultierte in einer erheblichen Beeinträchtigung des
Zellüberlebens. | de |
dc.format.mimetype | application/pdf | de |
dc.language.iso | eng | de |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | de |
dc.title | Calreticulin in kidney function and disease: chronic low level of calreticulin impairs Ca2+ homeostasis leading to mitochondrial dysfunction and chronic renal injury | de |
dc.type | doctoralThesis | de |
dc.title.translated | Bedeutung der Calreticulin in Nierenfunktion und -Erkrankung: chronisch niedrige Calreticulin-Konzentration beeinträchtigt die Ca2+-Homöostase und führt zu mitochondrialer Dysfunktion und chronischer Nierenschädigung | de |
dc.contributor.referee | Hoyer-Fender, Sigrid Prof. Dr. | de |
dc.date.examination | 2012-10-11 | de |
dc.subject.dnb | 570 Biowissenschaften, Biologie | de |
dc.subject.gok | Biologie | de |
dc.description.abstracteng | Chronic kidney disease (CKD) is becoming a
major public health problem worldwide. The persistent progression
of CKD is postulated to result from a self-perpetuating vicious
cycle of events activated after initial injury. Being a major
excretory and homeostatic organ of the body, kidney is continuously
exposed to toxic wastes, excess of water and ions. In an attempt to
understand the molecular mechanisms, which lead a normal
functioning kidney towards disease state, proteomic screening of
renal cells under various physiological conditions such as osmotic
stress, oxidative stress and cytokines were performed. The data
highlighted the expression regulation of an endoplasmic reticulum
resident Ca2+ binding protein, calreticulin. Within endoplasmic
reticulum (ER), calreticulin plays important function as a chaperon
directing proper conformation of proteins, as well as a major ER
Ca2+ binding protein, which controls cytosolic and ER Ca2+ levels.
The purpose of this study was to investigate the potential role of
calreticulin and mechanisms connecting this protein in regulating
the renal cells function and progression of renal injury. In vitro
investigations described in Chapter 2 using two-dimensional
fluorescence difference gel electrophoresis combined with mass
spectrometry analysis revealed an expression alteration of
calreticulin in renal cells under osmotic stress conditions. It was
also found that downregulation of calreticulin is combined with
continuous change in the level of free intracellular Ca2+. On the
other hand, inhibition of the Ca2+ release, through IP3R
antagonist, prevented calreticulin expression alteration under
hyperosmotic stress, whereas the cell viability was significantly
impaired. An increase in ER Ca2+ storage with decreased cell
viability was observed in cells overexpressing wild type
calreticulin compared to no significant change in Ca2+ level and
viability in cells overexpressing mutant calreticulin, lacking the
Ca2+ binding domain. Furthermore, free Ca2+ level and cell survival
were significantly improved under osmotic stress conditions by
silencing calreticulin with siRNA. Taken together, our data clearly
highlight the crucial role of calreticulin in renal cells
functioning and survival through modulating Ca2+ homeostasis under
osmotic stress conditions. The work presented in Chapter 3 was
performed with adult heterozygote Calr+/- mice having chronic low
level of calreticulin to further investigate the in vivo impact of
downregulation of calreticulin on kidney structure and function. A
progression of renal injury evidenced by development of
glomerulosclerosis and tubulointerstitial damage was observed in
histological analysis of Calr+/- mice kidneys from different age
groups. The significant overexpression of cytosolic Ca2+ binding
proteins with an insignificant alteration of ER stress proteins,
suggested the role of intracellular Ca2+ homeostasis disturbance in
renal impairments in Calr+/- mice. It was also found that
endoplasmic reticulum stress protein markers are not significantly
induced. Proteomic analysis further highlighted the role of
oxidative stress and mitochondrial dysfunction in renal injury in
Calr+/- mice kidneys. Especially, the reactive oxidative species
scavenging enzyme, Sod1 expression was not only significantly
downregulated but also showed irregular aggregates with
immunohistochemical staining. Ultrastructural analysis further
indicated significantly impaired mitochondrial morphology
characterized by enlarged, swollen mitochondria with disturbed
membranous structures in Calr+/- mice. These morphological changes
were accompanied by biochemical abnormalities with specific
decreases in the activity of cytochrome c oxidase of the
mitochondrial electron transfer chain. Consequently, the oxidative
stress together with mitochondrial damage and energy imbalance
resulted in kidney injury in Calr+/- mice. In conclusion, the work
presented in this thesis, revealed for the first time, the role of
calreticulin in renal cells function and in the progression of
chronic kidney injury. The study also points out that low level of
calreticulin mediated Ca2+ homeostasis disturbances impacts the
mitochondrial morphology, function and expression of Sod1. It will
be interesting to investigate the exact mechanism by which
calreticulin modulates Sod1 downregulation, at the molecular level.
This should provide more concentrated foci for future
experimentation. However, our findings highlighted a new potential
mechanism of the progression of CKD and encourage new directions in
CKD research, which in turn should have impact on treatment
approach, diagnosis and prevention of CKD. | de |
dc.contributor.coReferee | Brockmöller, Jürgen Prof. Dr. | de |
dc.subject.topic | Biology (incl. Psychology) | de |
dc.subject.ger | Calreticulin | de |
dc.subject.ger | Niere | de |
dc.subject.ger | CKD | de |
dc.subject.ger | chronischer Nierenschädigung | de |
dc.subject.eng | Calreticulin | de |
dc.subject.eng | Kidney | de |
dc.subject.eng | CKD | de |
dc.subject.eng | chronic kidney disease | de |
dc.subject.bk | Biologie | de |
dc.identifier.urn | urn:nbn:de:gbv:7-webdoc-3818-3 | de |
dc.identifier.purl | webdoc-3818 | de |
dc.affiliation.institute | Biologische Fakultät | de |
dc.identifier.ppn | 737897775 | de |