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Proteomic analysis of mitochondria in APOE transgenic mice and in response to an ischemic challenge.

ABSTRACT: Apolipoprotein E (APOE)-?4 is associated with a deleterious outcome after ischemic brain injury, which may involve abnormal regulation of mitochondrial function. We have assessed the mitochondrial proteomic response of APOE-?3 and APOE-?4 transgenic mice to transient global ischemic injury in the hippocampus. A genotype-dependent increase in ApoE levels in mitochondria was observed after ischemia, with APOE-?4 mice showing significantly greater increases than APOE-?3 mice. Quantitative analysis of the mitochondria-enriched fractions was performed using liquid-chromatography mass spectrometry coupled to label-free analysis. Of the 1,067 identified proteins, 274 were mitochondria associated. Mitochondrial protein expression was significantly different between genotypes under basal conditions as well as in response to global ischemia. A total of 12 mitochondrial proteins (including respiratory chain proteins NDUFA11, NDUFS3, NDUF5B, ATP5J, as well as ETFA, CYB5B, ATP6V1A, HSPA1B, OXR1, GLUL, IARS2, and PHYHIPL) were significantly altered with respect to genotype, global ischemia, or their interaction (P<0.01). A compelling interactome, created using proteins found to be significantly modulated by global ischemia (P<0.05), involved proteins that regulate energy production and oxidative stress. Thus, APOE genotype has a differential effect on the mitochondrial protein expression in the absence and presence of an injury, which may underlie the differing genotype susceptibility.

SUBMITTER: James R

PROVIDER: S-EPMC3323298 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Proteomic analysis of mitochondria in APOE transgenic mice and in response to an ischemic challenge.

James Rachel R Searcy James L JL Le Bihan Thierry T Martin Sarah F SF Gliddon Catherine M CM Povey Joanne J Deighton Ruth F RF Kerr Lorraine E LE McCulloch James J Horsburgh Karen K

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 20110831 1

Apolipoprotein E (APOE)-ɛ4 is associated with a deleterious outcome after ischemic brain injury, which may involve abnormal regulation of mitochondrial function. We have assessed the mitochondrial proteomic response of APOE-ɛ3 and APOE-ɛ4 transgenic mice to transient global ischemic injury in the hippocampus. A genotype-dependent increase in ApoE levels in mitochondria was observed after ischemia, with APOE-ɛ4 mice showing significantly greater increases than APOE-ɛ3 mice. Quantitative analysis ...[more]

PMID: 21878944

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Project description:BackgroundThe mitochondria and endoplasmic reticulum (ER) communicate via contact sites known as mitochondria associated membranes (MAMs). Many important cellular functions such as bioenergetics, mitophagy, apoptosis, and calcium signaling are regulated by MAMs, which are thought to be closely related to ischemic reperfusion injury (IRI). However, there exists a gap in systematic proteomic research addressing the relationship between these cellular processes.MethodsA 4D label free mass spectrometry-based proteomic analysis of mitochondria associated membranes (MAMs) from the human renal proximal tubular epithelial cell line (HK-2 cells) was conducted under both normal (N) and hypoxia/reperfusion (HR) conditions. Subsequent differential proteins analysis aimed to characterize disease-relevant signaling molecules. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was applied to total proteins and differentially expressed proteins, encompassing Biological Process (BP), Cell Component (CC), Molecular Function (MF), and KEGG pathways. Further, Protein-Protein Interaction Network (PPI) exploration was carried out, leading to the identification of hub genes from differentially expressed proteins. Notably, Mitofusion 2 (MFN2) and BCL2/Adenovirus E1B 19-kDa interacting protein 3(BNIP3) were identified and subsequently validated both in vitro and in vivo. Finally, the impact of MFN2 on MAMs during hypoxia/reoxygenation was explored through regulation of gene expression. Subsequently, a comparative proteomics analysis was conducted between OE-MFN2 and normal HK-2 cells, providing further insights into the underlying mechanisms.ResultsA total of 4489 proteins were identified, with 3531 successfully quantified. GO/KEGG analysis revealed that MAM proteins were primarily associated with mitochondrial function and energy metabolism. Differential analysis between the two groups showed that 688 proteins in HR HK-2 cells exhibited significant changes in expression level with P-value < 0.05 and HR/N > 1.5 or HR/N < 0.66 set as the threshold criteria. Enrichment analysis of differentially expressed proteins unveiled biological processes such as mRNA splicing, apoptosis regulation, and cell division, while molecular functions were predominantly associated with energy metabolic activity. These proteins play key roles in the cellular responses during HR, offering insights into the IRI mechanisms and potential therapeutic targets. The validation of hub genes MFN2 and BNIP3 both in vitro and vivo was consistent with the proteomic findings. MFN2 demonstrated a protective role in maintaining the integrity of mitochondria associated membranes (MAMs) and mitigating mitochondrial damage following hypoxia/reoxygenation injury, this protective effect may be associated with the activation of the PI3K/AKT pathway.ConclusionsThe proteins located in mitochondria associated membranes (MAMs) are implicated in crucial roles during renal ischemic reperfusion injury (IRI), with MFN2 playing a pivotal regulatory role in this context.

Project description:Male prevalence is an outstanding characteristic of hepatocellular carcinoma (HCC), and the underlying mechanisms for this have remained largely unknown. In the present study, Hras12V transgenic mice, in which hepatocyte-specific expression of the ras oncogene induces male-biased hepatic tumorigenesis, were studied, and altered proteins were detected by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). Protein samples from hepatic tumor tissues (T) and peritumor tissues (P) of transgenic males and females and the corresponding normal liver tissues (Wt) of nontransgenic males and females were subjected to pairwise comparisons based on proteomic analysis. Among 2381 autodetected protein spots, more than 1600 were differentially expressed based on a pairwise comparison (|ratio| > = 1.5, p < = 0.05). Of these, 180 spots were randomly selected for matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) identification; finally, 89 distinct proteins were obtained. Among these 89 proteins, 7 and 50 proteins were further validated by Western blotting and literature investigation, respectively. Intriguingly, compared with Wt, the altered proteins were relatively concentrated in T in transgenic females but in P in transgenic males. Consistently, the levels of p-ERK and p-mTOR were significantly higher in the T of females compared with that of males. The pathway enrichment assay showed that 5 pathways in males but only 1 in females were significantly altered in terms of the upregulated proteins in T compared with Wt. These data indicate that female hepatocytes are disturbed by oncogenes with great difficulty, whereas male hepatocytes readily do so. In addition, 33 proteins were gender-dependently altered in hepatic tumorigenesis. Moreover, 4% DNA packaging and 4% homeostasis-related functional proteins were found in females but not in males, and more nucleus proteins were found in females (8%) than in males (3%). In conclusion, the proteomic data and comparative analysis presented here offer crucial clues for elucidating the mechanisms that underlie the male prevalence in HCC.

Dataset Information

Proteomic analysis of mitochondria in APOE transgenic mice and in response to an ischemic challenge.

Publications

Proteomic analysis of mitochondria in APOE transgenic mice and in response to an ischemic challenge.

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