Transcriptional and Signaling Analysis As a Means of Investigating the Complexity of Aging Processes in Human and Mouse
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Transcriptional and signaling analysis as a means of investigating the complexity of aging processes in human and mouse Dissertation zur Erlangung des akademischen Grades des Doktors der Naturwissenschaften (Dr. rer. nat.) eingereicht im Fachbereich Biologie, Chemie, Pharmazie der Freien Universität Berlin vorgelegt von Thore C. Brink aus Herdecke August 2008 1. Gutachter: Prof. Dr. Hans Lehrach, Max-Planck-Institut für Molekulare Genetik 2. Gutachter: Prof. Dr. Volker Erdmann Freie Universität Berlin Disputation am 27.03.2009 Acknowledgment Acknowledgment Ich danke Herrn Professor Lehrach für die Betreuung, das Interesse und die Unterstützung beim Durchführen dieser Arbeit sowie für die Überlassung des Themas und die Möglichkeit die Dissertation am Max-Planck-Institut für Molekulare Genetik anzufertigen. Des Weiteren danke ich Herrn Professor Erdmann für das Interesse und die Unterstützung beim Durchführen dieser Arbeit. Ein besonderer Dank gebührt Herrn Dr. James Adjaye für die Korrektur, Unterstützung und Anleitung bei der Anfertigung meiner Dissertation sowie für die angenehme Zusammenarbeit während der letzten Jahre. Den Mitgliedern meiner Arbeitsgruppe sowie allen anderen Mitarbeitern und Doktoranden des Max-Planck-Instituts für Molekulare Genetik danke ich für die gute Zusammenarbeit und das gute Arbeitsklima. Meiner Familie danke ich herzlich für vielerlei Unterstützung, Aufmunterung und Anerkennung während der zurückliegenden Zeit. Hervorzuheben sind meine Frau Nicole und meine Eltern Dr. Kurt und Carmen Brink. Ich danke herzlich meinen Freunden für ihre Unterstützung und Aufmunterung während der zurückliegenden Zeit. Danke Andreas und Marc für die tatkräftige Unterstützung bei der Korrektur und viele anregende Gespräche. Vielen Dank Metzler für das Erstellen der PDF Version dieser Arbeit. Contents Contents ABBREVIATIONS V LIST OF FIGURES VII LIST OF TABLES IX ABSTRACT XI ABSTRACT (GERMAN) XIII 1. INTRODUCTION 1 1.1 Aging 1 1.1.1 Aging theories 1 1.1.2 Model systems in aging research 5 1.1.3 Human skin aging 9 1.2 Whole genome microarray analyses 10 1.2.1 Molecular methods employed for gene expression analyses 10 1.2.2 Advantages and disadvantages of whole genome studies 11 1.2.3 Gene expression microarrays and aging 12 1.3 Aim of this work 13 I Contents 2. MATERIAL AND METHODS 14 2.1 Model systems 14 2.1.1 Cell cultures 14 2.1.2 Human skin biopsies 14 2.1.3 Mice 15 2.2 RNA analyses 15 2.2.1 Total RNA isolation 15 2.2.2 RNA and cDNA quantification 16 2.2.3 Agarose gel electrophoresis 17 2.2.4 Reverse transcription 17 2.2.5 Real-time polymerase chain reaction (Real-Time PCR) 18 2.2.6 ENSEMBL chip hybridisation 18 2.2.7 Illumina bead chip hybridisation 20 2.2.8 Pathway analysis 21 2.3 Protein analyses 21 2.3.1 Protein isolation 21 2.3.2 Protein quantification (Bradford) 22 2.3.3 SDS-PAGE gel electrophoresis 22 2.3.4 Western blotting 23 2.4 Metabolite analyses 24 2.4.1 Lipid hydroperoxide (LPO) measurement 24 2.5 Histology 24 2.5.1 Section preparation 24 2.5.2 Hematoxylin Eosin staining 25 II Contents 3. RESULTS 27 3.1 Global data analysis 27 3.1.1 Global gene expression analysis 27 3.1.2 RNA quality control 29 3.1.3 Target gene lists 30 3.1.4 Pathway analyses 31 3.1.5 Array data confirmation by Real-Time PCR 31 3.2 Human skin aging 33 3.2.1 Genetic changes in age-dependent hormone-treated cell cultures 33 3.2.2 Gene expression in young and old sun-protected skin biopsies 35 3.2.3 Analogous gene expression of in vitro and in vivo skin samples 38 3.3 Mouse aging (brain, heart & kidney) 40 3.3.1 Synchronizing the sample collection 40 3.3.2 Physical and morphological differences of young and aged mice 45 3.3.3 Age-dependent gene expression in mouse brain, heart and kidney 46 3.3.4 Age-related post-transcriptional and structural changes 53 3.4 Comparison of human and mouse aging 55 3.4.1 Correlation of age-regulated target genes 55 3.4.2 Correlation of age-regulated Kegg pathways and Gene Ontologies (BP and CC) 57 3.4.3 Correlation of target genes to published data 62 III Contents 4. DISCUSSION 64 4.1 Global data analysis 64 4.2 Human skin aging 67 4.3 Mouse aging 72 4.4 The basis of aging 76 5. CONCLUSION 78 REFERENCES A PUBLICATIONS L CURRICULUM VITAE M APPENDIX N I Buffers for SDS-PAGE gel electrophoresis N II Buffers for western blotting O III Target gene lists P IV David output tables W IV Abbreviations Abbreviations Abbreviations AGEs advanced glycation end products aRNA amplified ribonucleic acid ATP adenosine triphosphate BP biological process BSA bovine serum albumin CC cellular compartment cDNA complementary deoxyribonucleic acid CLS chronological life span CR caloric restriction Ct threshold cycle DNA deoxyribonucleic acid dNTP deoxyribonucleotide triphosphate DR dietary restriction GO gene ontology LPO lipid hydroperoxide MHC major histocompatibility complex mRNA messenger ribonucleic acid PBS phosphate buffered saline PCR polymerase chain reaction PFA paraformaldehyde RLS replicative life span RNA ribonucleic acid ROS radical oxygen species RT room temperature SDS sodium dodecyl sulfate SSC sodium chloride/sodium citrate V Abbreviations Semantics °C degrees Celsius µg micrograms µl microlitres µM micromol g grams / gravity hr/hrs hours M mol mA milliampere mg milligrams min minutes ml millilitres mm millimetres mM millimol ng nanograms nm nanometres pg picograms pmol picomol s seconds U units V volt VI List of Figures List of Figures • Figure 1.1 The dual role of ROS and its contribution to aging. 4 • Figure 2.1 Sample output of pathway and GO analyses. 21 • Figure 3.1 Clustering of samples and correlation factors for mouse and human in vivo experiments. 28 • Figure 3.2 RNA quality control gel pictures. 30 • Figure 3.3 Venn diagrams visualizing the overlap of the in vitro and in vivo skin aging results. 39 • Figure 3.4 Clustering of samples and correlation factors for synchronization experiments. 41 • Figure 3.5 Scatter plots highlighting the regulation of circadian rhythm genes. 42 • Figure 3.6 Real-Time PCR experiments investigating circadian rhythm gene expression. 43 • Figure 3.7 Morphological differences of young and aged mice. 45 • Figure 3.8 Overlapping target genes of synchronised and unsynchronised aging samples. 50 • Figure 3.9 Investigations beyond the RNA levels. 53 • Figure 3.10 Venn diagram visualizing the overlap of common regulated target genes in the mouse in vivo and human in vivo and in vitro samples. 55 • Figure 3.11 4-way Venn diagrams visualizing the detailed overlap of regulated target genes in the mouse in vivo and human in vivo and in vitro samples. 56 • Figure 3.12 Venn diagram visualizing the overlap of common regulated Kegg pathways in the mouse in vivo and human in vivo and in vitro samples. 57 • Figure 3.13 4-way Venn diagrams visualizing the detailed overlap of regulated Kegg pathways in the mouse in vivo and human in vivo and in vitro samples. 58 VII List of Figures • Figure 3.14 Venn diagram visualizing the overlap of common regulated biological processes in the mouse in vivo and human in vivo and in vitro samples. 59 • Figure 3.15 4-way Venn diagrams visualizing the detailed overlap of regulated biological processes in the mouse in vivo and human in vivo and in vitro samples. 60 • Figure 3.16 Venn diagram visualizing the overlap of common regulated cellular compartments in the mouse in vivo and human in vivo samples. 61 • Figure 3.17 4-way Venn diagrams visualizing the detailed overlap of regulated cellular compartments in the mouse in vivo and human in vivo samples. 61 VIII List of Tables List of Tables • Table 3.1 Number of target genes for all in vitro and in vivo aging experiments. 30 • Table 3.2 Array data confirmation by Real-Time PCR. 32 • Table 3.3 List of overlapping genes regulated in skin fibroblasts and sebocytes with age. 34 • Table 3.4 List of overlapping biological processes regulated in fibroblasts and sebocytes with age. 35 • Table 3.5 List of overlapping genes regulated in male and female skin biopsies with age. 37 • Table 3.6 List of overlapping pathways and GOs regulated in male and female skin biopsies with age. 38 • Table 3.7 List of overlapping biological processes regulated in the in vitro and in vivo experiments. 39 • Table 3.8 Circadian rhythm genes regulated in mouse brain, heart and kidney. 40 • Table 3.9 Most-regulated genes in a 16hrs period in mouse kidney. 44 • Table 3.10 List of overlapping genes regulated in mouse brain, heart and kidney with age. 47 • Table 3.11 List of overlapping pathways and GOs regulated in mouse brain, heart and kidney with age. 48 • Table 3.12 List of overlapping genes regulated in synchronised and unsynchronised brain samples. 49 • Table 3.13 List of overlapping genes regulated in synchronised and unsynchronised heart samples. 51 • Table 3.14 List of overlapping genes regulated in synchronised and unsynchronised kidney samples. 52 IX List of Tables • Table 3.15 Results of the LPO measurement. 54 • Table 3.16 List of overlapping target genes in Lener et al. (2006) and the investigated human skin samples. 62 • Table 3.17 List of overlapping target genes in the AGEMAP database and the investigated mouse tissues (brain, heart, kidney). 63 • Table X.1 Target gene list for human skin fibroblasts. P • Table X.2 Target gene list for human sebocytes. Q • Table X.3 Target gene list for female human skin biopsies. R • Table X.4 Target gene list for male human skin biopsies.