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Senescence markers in focal nodular hyperplasia of the liver: pathogenic considerations on the basis of immunohistochemical results
Focal nodular hyperplasia (FNH) is a polyclonal tumour-like hepatic lesion characterised by parenchymal nodules, connective tissue septa without interlobular bile ducts, pronounced ductular reaction and inflammation. It may represent a response to local arterial hyperperfusion and hyperoxygenation resulting in oxidative stress.
We aimed at obtaining closer insight into the pathogenesis of FNH with its characteristic morphologic features. Immunohistochemistry and immunofluorescence microscopy was performed on FNH specimens using antibodies against keratins (K) 7 and 19, neural cell adhesion molecule (NCAM), lamin B1, senescence markers (CDK inhibitor 1/p21Cip1, CDK inhibitor /p16Ink4a, senescence-associated (SA) β- galactosidase activity), proliferation markers (Ki-67, proliferating-cell nuclear antigen (PCNA)), and the abnormally phosphorylated histone γ-H2AX, indicating DNA double strand breaks; moreover SA β- galactosidase activity was determined histochemical.
Ductular metaplasia of hepatocytes indicated by K7 expression in the absence of K19 plays a major role in the development of ductular reaction in FNH. Moreover, the expression of senescence markers (p21Cip1, p16Ink4a, γ-H2AX, SA β-galactosidase activity) in hepatocytes and cholangiocytes suggests that stress-induced cellular senescence contributes to fibrosis and inflammation via production of components of the senescence-associated secretory phenotype.
Expression of proliferation markers (Ki-67, PCNA) was not enhanced in hepatocytes and biliary cells. Senescence and ductular metaplasia of hepatocytes may thus be involved in inflammation, fibrosis and apoptosis resistance. Hence, fibrosis, inflammation and reduced apoptotic cell death, rather than proliferation (hyperplasia) may be responsible for increased tissue mass and tumour-like appearance of FNH.
Super-Resolution Imaging of the A- and B-Type Lamin Networks: A Comparative Study of Different Fluorescence Labeling Procedures
A- and B-type lamins are type V intermediate filament proteins. Mutations in the genes encoding these lamins cause rare diseases, collectively called laminopathies. A fraction of the cells obtained from laminopathy patients show aberrations in the localization of each lamin subtype, which may represent only the minority of the lamina disorganization.
To get a better insight into more delicate and more abundant lamina abnormalities, the lamin network can be studied using super-resolution microscopy. We compared confocal scanning laser microscopy and stimulated emission depletion (STED) microscopy in combination with different fluorescence labeling approaches for the study of the lamin network.
We demonstrate the suitability of an immunofluorescence staining approach when using STED microscopy, by determining the lamin layer thickness and the degree of lamin A and B1 colocalization as detected in fixed fibroblasts (co-)stained with lamin antibodies or (co-)transfected with EGFP/YFP lamin constructs. This revealed that immunofluorescence staining of cells does not lead to consequent changes in the detected lamin layer thickness, nor does it influence the degree of colocalization of lamin A and B1, when compared to the transfection approach.
Studying laminopathy patient dermal fibroblasts (LMNA c.1130G>T (p.(Arg377Leu)) variant) confirmed the suitability of immunofluorescence protocols in STED microscopy, which circumvents the need for less convenient transfection steps. Furthermore, we found a significant decrease in lamin A/C and B1 colocalization in these patient fibroblasts, compared to normal human dermal fibroblasts. We conclude that super-resolution light microscopy combined with immunofluorescence protocols provides a potential tool to detect structural lamina differences between normal and laminopathy patient fibroblasts.
Nuclear IMPDH Filaments in Human Gliomas
The analysis of nuclear morphology plays an important role in glioma diagnosis and grading. We previously described intranuclear rods (rods) labeled with the SDL.3D10 monoclonal antibody against class III beta-tubulin (TUBB3) in human ependymomas. In a cohort of adult diffuse gliomas, we identified nuclear rods in 71.1% of IDH mutant lower-grade gliomas and 13.7% of IDH wild-type glioblastomas (GBMs).
The presence of nuclear rods was associated with significantly longer postoperative survival in younger (≤65) GBM patients. Consistent with this, nuclear rods were mutually exclusive with Ki67 staining and their prevalence in cell nuclei inversely correlated with the Ki67 proliferation index. In addition, rod-containing nuclei showed a relative depletion of lamin B1, suggesting a possible association with senescence. To gain insight into their functional significance, we addressed their antigenic properties.
Using a TUBB3-null mouse model, we demonstrate that the SDL.3D10 antibody does not bind TUBB3 in rods but recognizes an unknown antigen. In the present study, we show that rods show immunoreactivity for the nucleotide synthesizing enzymes inosine monophosphate dehydrogenase (IMPDH) and cytidine triphosphate synthetase. By analogy with the IMPDH filaments that have been described previously, we postulate that rods regulate the activity of nucleotide-synthesizing enzymes in the nucleus by sequestration, with important implications for glioma behavior.
The Long Linker Region of Telomere-Binding Protein TRF2 Is Responsible for Interactions with Lamins
Telomere-binding factor 2 (TRF2) is part of the shelterin protein complex found at chromosome ends. Lamin A/C interacts with TRF2 and influences telomere position. TRF2 has an intrinsically disordered region between the ordered dimerization and DNA-binding domains. This domain is referred to as the long linker region of TRF2, or udTRF2.
We suggest that udTRF2 might be involved in the interaction between TRF2 and lamins. The recombinant protein corresponding to the udTRF2 region along with polyclonal antibodies against this region were used in co-immunoprecipitation with purified lamina and nuclear extracts.
Co-immunoprecipitation followed by Western blots and mass spectrometry indicated that udTRF2 interacts with lamins, preferably lamins A/C. The interaction did not involve any lamin-associated proteins, was not dependent on the post-translation modification of lamins, nor did it require their higher-order assembly.
Besides lamins, a number of other udTRF2-interacting proteins were identified by mass spectrometry, including several heterogeneous nuclear ribonucleoproteins (hnRNP A2/B1, hnRNPA1, hnRNP A3, hnRNP K, hnRNP L, hnRNP M), splicing factors (SFPQ, NONO, SRSF1, and others), helicases (DDX5, DHX9, and Eif4a3l1), topoisomerase I, and heat shock protein 71, amongst others.
Lamin B1 antibody |
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| 23038 | SAB | 100ul | EUR 479 |
Lamin B1 antibody |
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| 23038-100ul | SAB | 100ul | EUR 468 |
Lamin B1 antibody |
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| 10R-8083 | Fitzgerald | 100 ug | EUR 466 |
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Description: Mouse monoclonal Lamin B1 antibody |
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Lamin B1 antibody |
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| 10R-6722 | Fitzgerald | 100 ug | EUR 846 |
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Description: Mouse monoclonal Lamin B1 antibody |
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Lamin B1 Antibody |
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| 3807-100 | Biovision | each | EUR 379.2 |
Lamin B1 Antibody |
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| 3807-30T | Biovision | each | EUR 175.2 |
Lamin B1 Antibody |
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| 48220 | SAB | 100ul | EUR 429 |
Lamin B1 Antibody |
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| 48220-100ul | SAB | 100ul | EUR 399.6 |
Lamin B1 Antibody |
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| 48220-50ul | SAB | 50ul | EUR 286.8 |
Lamin B1 Antibody |
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| C30101-100ul | Assay Biotech | 100μl | EUR 217 |
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Description: Lamin B1 Rabbit Polyclonal Antibody |
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Lamin B1 Antibody |
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| C30101-50ul | Assay Biotech | 50μl | EUR 143.5 |
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Description: Lamin B1 Rabbit Polyclonal Antibody |
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Lamin B1 Antibody |
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| DF6687 | Affbiotech | 200ul | EUR 420 |
Lamin B1 Antibody |
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| DF6687-100ul | Affinity Biosciences | 100ul | EUR 168 |
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Description: WB,IHC,ELISA(peptide) |
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Lamin B1 Antibody |
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| DF6687-200ul | Affinity Biosciences | 200ul | EUR 210 |
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Description: WB,IHC,ELISA(peptide) |
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Lamin B1 Antibody |
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| AF5161 | Affbiotech | 1ml | EUR 1440 |
Lamin B1 Antibody |
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| AF5161-100ul | Affinity Biosciences | 100ul | EUR 150 |
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Description: WB,IHC,IF/ICC,ELISA(peptide) |
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Lamin B1 Antibody |
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| AF5161-1ml | Affinity Biosciences | 1ml | EUR 720 |
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Description: WB,IHC,IF/ICC,ELISA(peptide) |
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Lamin B1 Antibody |
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| AF5161-200ul | Affinity Biosciences | 200ul | EUR 210 |
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Description: WB,IHC,IF/ICC,ELISA(peptide) |
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Lamin B1 Antibody |
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| AF5161-50ul | Affinity Biosciences | 50ul | EUR 90 |
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Description: WB,IHC,IF/ICC,ELISA(peptide) |
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Lamin B1 Antibody |
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| BF1002 | Lifescience Market | 100 ug | EUR 562.8 |
Lamin B1 antibody |
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| CAF50196-100ug | Biomatik Corporation | 100ug | EUR 312 |
Lamin B1, Antibody |
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| GWB-A70975 | GenWay Biotech | 0.1 mg | Ask for price |
Lamin B1 Antibody |
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| E38PA9196 | EnoGene | 100ul | EUR 225 |
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Description: Available in various conjugation types. |
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Lamin B1 Antibody |
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| E38PA9414 | EnoGene | 100ul | EUR 225 |
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Description: Available in various conjugation types. |
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Lamin B1 Antibody |
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| E38PA1693 | EnoGene | 100ul | EUR 225 |
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Description: Available in various conjugation types. |
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Lamin B1 Antibody |
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| MBS5311486-01mg | MyBiosource | 0.1mg | EUR 470 |
Lamin B1 Antibody |
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| MBS5311486-5x01mg | MyBiosource | 5x0.1mg | EUR 2080 |
Lamin B1 Antibody |
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| MBS5311894-01mL | MyBiosource | 0.1mL | EUR 1070 |
Lamin B1 Antibody |
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| MBS5311894-5x01mL | MyBiosource | 5x0.1mL | EUR 4655 |
Some of the identified interactors are known to be involved in telomere biology; the roles of the others remain to be investigated. Thus, the long linker region of TRF2 (udTRF2) is a regulatory domain responsible for the association between TRF2 and lamins and is involved in interactions with other proteins.
