Fluorescence in situ hybridization analysis of the fos/jun ratio in the ageing brain

Temporal pattern of Fos and Jun families expression after mitogenic stimulation with FGF-2 in rat neural stem cells and fibroblasts

Intense stimulation of most living cells triggers the activation of immediate early genes, such as Fos and Jun families. These genes are important in cellular and biochemical processes, such as mitosis and cell death. The present study focused on determining the temporal expression pattern of Fos and Jun families in fibroblasts and neural stem cells of cerebellum, hippocampus, and subventricular zone (SVZ) of rats of different ages at 0, 0.5, 1, 3, and 6 h after stimulation with fibroblast growth factor (FGF)-2. In neonates, a similar expression pattern was observed in all cells analyzed, with lower expression in basal condition, peak expression at 0.5 h after stimulation, returning to baseline values between 1 and 3 h after stimulation. On the other hand, cells from adult animals only showed Fra1 and JunD expression after stimulation. In fibroblasts and hippocampus, Fra1 reached peak expression at 0.5 h after stimulation, while in the SVZ, peak level was observed at 6 h after stimulation. JunD in fibroblasts presented two peak expressions, at 0.5 and 6 h after stimulation. Between these periods, the expression observed was at a basal level. Nevertheless, JunD expression in SVZ and hippocampus was low and without significant changes after stimulation. Differences in mRNA expression in neonate and adult animals characterize the significant differences in neurogenesis and cell response to stimulation at different stages of development. Characterizing these differences might be important for the development of cell cultures, replacement therapy, and the understanding of the physiological response profile of different cell types.

Livin, a novel marker in lymphoma type distinction

Despite advances in immunohistochemical and molecular diagnostics, there are persistent difficulties in differentiating between several subtypes of non-Hodgkin lymphoma (NHL) and classic Hodgkin lymphoma (CHL). Considering high level of livin expression in hematologic malignancies, we aimed to examine the utility of livin expression ratio, as an ancillary biomarker, in distinguishing CHL from NHL in ambiguous cases. We evaluated livin expression in 38 CHL, 23 NHL, and 39 nonneoplastic lymph nodes in paraffin-embedded blocks. Tissue microarray-based semiquantitative immunoflourecent staining was applied for protein expression. Criterion standard of diagnosis was based on selection of only definite cases and not the cases suspected by hemathopathologists. A significant difference was found in the livin/GAPDH mean ratio (M.R) of expression between NHL and CHL cases. A receiver operating characteristic curve analysis confirmed 0.6370 to be the best diagnostic cut-off value for the livin/GAPDH expression M.R in diffuse large B-cell lymphoma (DLBCL) (area under the curve = 0.944); it yielded 92% sensitivity, 94% specificity, likelihood ratios positive 17.5, and likelihood ratios negative 0.07 for diagnosing DLBCL from CHL. Mean ratio of livin/Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression seems to be a valuable index in differentiating DLBCL from CHL. We suggested an optimal cut-off point for livin/GAPDH expression M.R with a high sensitivity and specificity. Thus, in diagnostically difficult cases of DLBCL and CHL, focus on livin as marker may provide useful corroborative information.

Age-related changes in the response of intestinal cells to 1α,25(OH)2-vitamin D3

The hormonally active form of vitamin D(3), 1α,25(OH)(2)-vitamin D(3), acts in intestine, its major target tissue, where its actions are of regulatory and developmental importance: regulation of intracellular calcium through modulation of second messengers and activation of mitogenic cascades leading to cell proliferation. Several causes have been postulated to modify the hormone response in intestinal cells with ageing, among them, alterations of vitamin D receptor (VDR) levels and binding sites, reduced expression of G-proteins and hormone signal transduction changes. The current review summarizes the actual knowledge regarding the molecular and biochemical basis of age-impaired 1α,25(OH)(2)-vitamin D(3) receptor-mediated signaling in intestinal cells. A fundamental understanding why the hormone functions are impaired with age will enhance our knowledge of its importance in intestinal cell physiology.

Apoptosis inhibition or inflammation: the role of NAIP protein expression in Hodgkin and non-Hodgkin lymphomas compared to non-neoplastic lymph node

Background

Inhibitors of Apoptosis (IAP) family play a critical role in apoptosis and inflammatory response. Neuronal Apoptosis Inhibitory Protein (NAIP), as a member of both IAPs and NLR families (NOD-Like Receptor), is a unique IAP harboring NOD (Nucleotide Oligomerization Domain) and LLR (Leucine Rich Repeat) motifs. Considering these motifs in NAIP, it has been suggested that the main function of NAIP is distinct from other members of IAPs. As a member of NLR, NAIP mediates the assembly of 'Inflammasome' for inflammatory caspase activation. Pathologic expression of NAIP has been reported not only in some infectious and inflammatory diseases but also in some malignancies. However, there is no report to elucidate NAIP expression in lymphomatic malignancies.

Methods

In this study, we examined NAIP protein expression in 101 Formalin-Fixed Paraffin-Embedded blocks including samples from 39 Hodgkin Lymphoma and 23 Non Hodgkin Lymphoma cases in comparison with 39 control samples (30 normal and 9 Reactive Lymphoid Hyperplasia (RLH) lymph nodes) using semi-quantitative immuno-flourecent Staining.

Results

NAIP expression was not statistically different in lymphoma samples neither in HL nor in NHL cases comparing to normal samples. However, we evaluated NAIP expression in normal and RLH lymph nodes. Surprisingly, we have found a statistically significant-difference between the NAIP expression in RLH (M.R of NAIP/GAPDH expression = 0.6365 ± 0.017) and normal lymph node samples (M.R of NAIP/GAPDH expression = 0.5882 ± 0.047) (P < 0.01).

Conclusions

These findings show that the regulation of apoptosis could not be the main function of NAIP in the cell, so the pathologic expression of NAIP is not involved in lymphoma. But, we concluded that the over expression of NAIP has more effective role in the inflammatory response. Also, this study clarifies the NAIP expression level in lymphoma which is required for IAPs profiling in order to be used in potential translational applications of IAPs.

Evaluation of ARG protein expression in mature B cell lymphomas compared to non-neoplastic reactive lymph node

The participation of Abl-Related Gene (ARG) is demonstrated in pathogenesis of different human malignancies. However there is no conclusive evidence on ARG expression level in mature B cell lymphomas. In this study we evaluated ARG protein expression in Follicular Lymphoma (FL), Burkitt's Lymphoma (BL) and Diffused Large B Cell Lymphoma (DLBCL) in comparison with non-neoplastic lymph nodes. Semi-quantitative fluorescent ImmunoHistoChemistry was applied on 14, 7 and 4 patients with DLBCL, FL and BL respectively, adding to 4 normal and 4 reactive lymph nodes. The mean ratio of ARG/GAPDH expression was significantly different (p<0.00) between lymphomas and control samples, with DLBCL having the highest ARG expression amongst all. Over expression of ARG was seen in FL and BL, with FL expressing statistically more ARG than BL. Moreover, the ARG/GAPDH expression ratio increased from DLBCL stage I towards stage VI, all showing significantly more ARG expression than FL and BL (in all cases p<0.00).

Dietary lipoic acid supplementation can mimic or block the effect of dietary restriction on life span

Dietary restriction feeding extends survival in a range of species but a detailed understanding of the underlying mechanism is lacking. There is interest therefore in identifying a more targeted approach to replicate this effect on survival. We report that in rats dietary supplementation with alpha-lipoic acid, has markedly differing effects on lifetime survival depending upon the dietary history of the animal. When animals are switched from DR feeding to ad libitum feeding with a diet supplemented with alpha-lipoic acid, the extended survival characteristic of DR feeding is maintained, even though the animals show accelerated growth. Conversely, switching from ad libitum feeding a diet supplemented with alpha-lipoic acid to DR feeding of the non-supplemented diet, blocks the normal effect of DR to extend survival, even after cessation of lipoic acid supplementation. Unlike the dynamic effect of switching between DR and ad libitum feeding with a non-supplemented diet where the subsequent survival trajectory is determined by the new feeding regime, lipoic acid fixes the survival trajectory to that established by the initial feeding regime. Ad libitum feeding a diet supplemented with lipoic acid can therefore act as mimetic of DR to extend survival.

Age-related alteration of 1alpha,25(OH)2-vitamin D3-dependent activation of p38 MAPK in rat intestinal cells

In intestinal cells, 1alpha,25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)) regulates gene expression via the specific intracellular vitamin D receptor and induces fast non-transcriptional responses involving stimulation of transmembrane signal transduction pathways. In the present study, we analyzed, for the first time, alterations in p38 MAPK response to 1alpha,25(OH)(2)D(3) in rat enterocytes with ageing. In enterocytes from young rats, the hormone increased, in a time- and dose-dependent fashion, the phosphorylation of p38 MAPK, peaking at 3 min (+2-fold). Basal levels of p38 MAPK phosphorylation were lower in enterocytes from old rats and the hormone response was greatly diminished (+0.5-fold at 3 min). p38 MAPK phosphorylation impairment in old animals was not related to significant changes of the kinase protein expression and do not explain the decreased response to 1alpha,25(OH)(2)D(3). Extracellular and intracellular Ca(2+) chelation or c-Src pharmacological inhibition suppressed hormone activation of p38 MAPK in both, young and aged rats, demonstrating that Ca(2+) and the non-receptor tyrosine kinase c-Src are required for full activation of p38 MAPK in cells stimulated with 1alpha,25(OH)(2)D(3). Two other vitamin D(3) metabolites, 25(OH)D(3) and 24,25(OH)(2)D(3, )also enhanced p38 phosphorylation, and to a similar extent than 1alpha,25(OH)(2)D(3), an ability that is lost with ageing. Enterocyte exposure to the hormone also resulted in the rapid induction of c-fos protein (peaking at 5 min, +3-fold) and to a greater extent than that of mRNA induction. With ageing, 1alpha,25(OH)(2)D(3)-dependent increase of c-fos protein level was diminished, but c-fos mRNA expression was not different from young animals. Impairment of 1alpha,25(OH)(2)D(3) activation of p38 MAPK upon ageing and abnormal hormone regulation of the c-fos oncoprotein synthesis may affect intestinal cell function.

Increased expression of the S25 ribosomal protein gene occurs during ageing of the rat liver

BACKGROUND

It appears that consistent changes in the levels of activity of a small cohort of genes (probably <1% of all active genes) occur in all mammalian cells during ageing. Identification of such genes could provide valuable insights into the ageing process.

OBJECTIVE

We have studied age-related changes in gene expression profiles in the rat liver. One of the genes which exhibited clear and consistent increases in expression is characterised.

METHODS

Analysis of the gene expression profile was carried out using a combination of an optimised form of differential display and single-strand conformational polymorphism (SSCP) gel analysis. Gene expression levels were quantified by Northern blot analysis. The gene's identity was determined by comparing its nucleotide sequence to DNA databases.

RESULTS

During this investigation we observed one gene which exhibited an increase in expression in livers from young adult (6 months) to old adult (24 months) rats. The differential expression of this gene was confirmed by SSCP gel analysis and Northern blotting. Densitometry of the latter indicated that expression increased by 165% with age. Characterisation of the isolated polymerase chain reaction fragment demonstrated it to code for the ribosomal protein S25 (RPS25).

CONCLUSIONS

This increase in RPS25 expression is further evidence that the composition of ribosomes may alter with age and as a result could have significant effects on protein synthesis.

Genes, telomeres and mammalian ageing

Although there appear to be several influences, which contribute to the ageing of mammals, the role of DNA appears to be pivotal. There is increasing evidence that oxidative damage is an important factor in producing mutations in genes, shortening telomeres and damaging mitochondrial DNA. Accumulation of mutations in genomic DNA could result in the gradual decline in cellular function, which is exhibited in a variety of tissues. The random nature of these mutations, could also offer an explanation for differences in the degree and time of onset of age-related changes, exhibited by different individuals. Shortening of telomeres, caused by oxidative damage or the end-replication problem, could result in the accumulation of post-mitotic cells in-vivo during ageing. This might impair certain aspects of physiology, such as wound healing. Mutation of mitochondrial DNA may also be important in causing loss of cells in post-mitotic tissues such as muscle or brain. In addition changes in the redox state during the life of an animal may alter transcription factor activities, leading to consistent changes in the gene expression profiles of mammalian tissues. The latter could explain consistent age-related changes that have been observed in cell structure and physiology. Although all of these mechanisms may make a contribution to ageing, it is likely that it is the interplay between them that produces the most prominent effects.

Altered composition of the AP-1 transcription factor in immortalized compared to normal proliferating cells

We have investigated the expression of the AP-1 transcription factor proteins, fos, fosB, fra1, fra2, jun, junB, junD, using Western blot analysis, in several types of asynchronously proliferating cells. The latter included normal fibroblasts, immortalized but not tumourigenic fibroblasts, and two immortalized tumour cell lines. All cells expressed fos, fra1 and jun proteins and none expressed fosB. There were, however, interesting qualitative differences between the normal fibroblasts and the immortalized cells. Expression of fra2 was difficult to detect in normal cells, but was very evident in all of the immortalized cells. The normal cells only expressed a 44 kDa junB species, whereas the immortalized cells expressed both this and another 34 kDa species. All of the cells expressed the two junD proteins but the smaller 39 kDa species was more prominent in the normal cells, whereas the larger 44 kDa protein was more prominent in the immortalized cells. These data indicate that immortalized cells are not simply cells in which the ageing process has been prevented or reversed, but instead exhibit additional characteristics to those associated with young normal cells.

Altered composition and DNA binding activity of the AP-1 transcription factor during the ageing of human fibroblasts

We have investigated the expression of AP-1 transcription factor proteins during the in-vitro ageing of human fibroblasts. The numbers of these cells that are in the cell cycle gradually decreases up to 45 cumulative population doublings (cPD), thereafter the decline is steeper, until almost all cells enter a post-mitotic state by 60 cPD. We observed that a 34 kd junB species began to replace the 44 kd junB species after 41 cPD. This was followed, after 44 cPD, by a loss of fra1 and both junD species. After 49 cPD there was a gradual decline in the levels of fos and jun proteins, but disproportionately, so that the fos/jun protein ratio also declined. Although fos and jun proteins were still clearly present at 60 cPD, utilisation of the AP-1 DNA consensus sequence could not be demonstrated after 54 cPD. These data indicate that significant changes occur in the composition of the AP-1 transcription factor during ageing, but also that alterations in its DNA binding activity may involve other factors.

AP-1 proteins in the adult brain: facts and fiction about effectors of neuroprotection and neurodegeneration

Jun and Fos proteins are induced and activated following most physiological and pathophysiological stimuli in the brain. Only few data allow conclusions about distinct functions of AP-1 proteins in neurodegeneration and neuroregeneration, and these functions mainly refer to c-Jun and its activation by JNKs. Apoptotic functions of activated c-Jun affect hippocampal, nigral and primary cultured neurons following excitotoxic stimulation and destruction of the neuron-target-axis including withdrawal of trophic molecules. The inhibition of JNKs might exert neuroprotection by subsequent omission of c-Jun activation. Besides endogenous neuronal functions, the c-Jun/AP-1 proteins can damage the nervous system by upregulation of harmful programs in non-neuronal cells (e.g. microglia) with release of neurodegenerative molecules. In contrast, the differentiation with neurite extension and maturation of neural cells in vitro indicate physiological and potentially neuroprotective functions of c-Jun and JNKs including sensoring for alterations in the cytoskeleton. This review summarizes the multiple molecular interfunctions which are involved in the shift from the physiological role to degenerative effects of the Jun/JNK-axis such as cell type-specific expression and intracellular localization of scaffold proteins and upstream activators, antagonistic phosphatases, interaction with other kinase systems, or the activation of transcription factors competing for binding to JNK proteins and AP-1 DNA elements.

Telomerase and mammalian ageing: a critical appraisal

The telomeres that occur at the end of chromosomes are maintained by the activity of telomerase and are thought to be important protective factors in maintaining the integrity of chromosomes. It now appears that in vitro replicative senescence, which has been observed in cultured somatic cells, is due to a loss of telomere length in those cells, caused by inactivity of telomerase. This has led to the proposition that telomerase activity is an important determinant in organismal ageing. However, many cells in the body do not proliferate regularly and therefore will not lose telomere length. Cells that do proliferate frequently have now been shown to have active telomerase. Other cells, such as fibroblasts, that do not have telomerase activity but proliferate only occasionally may not reach the Hayflick limit during the lifetime of an animal. There is also no correlation between telomere length and the maximal lifespan exhibited by different species. Studies of telomerase knock-out mice have reported some aspects of accelerated ageing after three generations, but the relevance of these observations to normal ageing remains unconvincing. The role of telomerase in producing immortal tumour cells and the possibility that activation of telomerase is an important event in malignant transformation is similarly controversial and open to alternative interpretations. The significance of these and other observations, and how they define the role of telomerase in ageing, is discussed.