Loss of Nfkb1 leads to early onset aging
01 Dec 2014-Vol. 6, Iss: 11, pp 931-943
TL;DR: Data show that loss of Nfkb1 leads to early animal aging that is associated with reduced apoptosis and increased cellular senescence, and support the strong link between the NF-(B pathway and mammalian aging.
Abstract: NF-κB is a major regulator of age-dependent gene expression and the p50/NF-κB1 subunit is an integral modulator of NF-κB signaling. Here, we examined Nfkb1-/- mice to investigate the relationship between this subunit and aging. Although Nfkb1-/- mice appear similar to littermates at six months of age, by 12 months they have a higher incidence of several observable age-related phenotypes. In addition, aged Nfkb1-/- animals have increased kyphosis, decreased cortical bone, increased brain GFAP staining and a decrease in overall lifespan compared to Nfkb1+/+. In vitro, serially passaged primary Nfkb1-/- MEFs have more senescent cells than comparable Nfkb1+/+ MEFs. Also, Nfkb1-/- MEFs have greater amounts of phospho-H2AX foci and lower levels of spontaneous apoptosis than Nfkb1+/+, findings that are mirrored in the brains of Nfkb1-/- animals compared to Nfkb1+/+. Finally, in wildtype animals a substantial decrease in p50 DNA binding is seen in aged tissue compared to young. Together, these data show that loss of Nfkb1 leads to early animal aging that is associated with reduced apoptosis and increased cellular senescence. Moreover, loss of p50 DNA binding is a prominent feature of aged mice relative to young. These findings support the strong link between the NF-κB pathway and mammalian aging.
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01 Jan 1981
1,737 citations
TL;DR: It is proposed that controlling senescence-associated inflammation by targeting specific inflammatory mediators may have a beneficial therapeutic effect in treatment of cancer and aging-related diseases.
296 citations
TL;DR: The more that can be understood about the interplay between SCs and the immune system, the faster new interventions may be developed to delay, prevent, or treat age-related dysfunction and the multiple senescence-associated chronic diseases and disorders.
249 citations
TL;DR: The CVID phenotype in these families is caused by NF-κB1 p50 haploinsufficiency, with a Dutch-Australian CVID-affected family identified a NFKB1 heterozygous splice-donor-site mutation, causing in-frame skipping of exon 8.
Abstract: Common variable immunodeficiency (CVID), characterized by recurrent infections, is the most prevalent symptomatic antibody deficiency. In ∼90% of CVID-affected individuals, no genetic cause of the disease has been identified. In a Dutch-Australian CVID-affected family, we identified a NFKB1 heterozygous splice-donor-site mutation (c.730+4A>G), causing in-frame skipping of exon 8. NFKB1 encodes the transcription-factor precursor p105, which is processed to p50 (canonical NF-κB pathway). The altered protein bearing an internal deletion (p.Asp191_Lys244delinsGlu; p105ΔEx8) is degraded, but is not processed to p50ΔEx8. Altered NF-κB1 proteins were also undetectable in a German CVID-affected family with a heterozygous in-frame exon 9 skipping mutation (c.835+2T>G) and in a CVID-affected family from New Zealand with a heterozygous frameshift mutation (c.465dupA) in exon 7. Given that residual p105 and p50—translated from the non-mutated alleles—were normal, and altered p50 proteins were absent, we conclude that the CVID phenotype in these families is caused by NF-κB1 p50 haploinsufficiency.
193 citations
TL;DR: Recent results reveal that the nuclear factor of kappa light polypeptide gene enhancer in B‐cells 1 (NFKB1) (p105/p50) subunit is an important regulator of NF‐κB activity in vivo, potentially revealing new strategies for targeting this pathway in inflammatory diseases and cancer.
Abstract: The pleiotropic consequences of nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) pathway activation result from the combinatorial effects of the five subunits that form the homo- and heterodimeric NF-κB complexes. Although biochemical and gene knockout studies have demonstrated overlapping and distinct functions for these proteins, much is still not known about the mechanisms determining context-dependent functions, the formation of different dimer complexes and transcriptional control in response to diverse stimuli. Here we discuss recent results that reveal that the nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NFKB1) (p105/p50) subunit is an important regulator of NF-κB activity in vivo. These effects are not restricted to being a dimer partner for other NF-κB subunits. Rather p50 homodimers have a critical role as suppressors of the NF-κB response, while the p105 precursor has a variety of NF-κB-independent functions. The importance of Nfkb1 function can be seen in mouse models, where Nfkb1(-/-) mice display increased inflammation and susceptibility to certain forms of DNA damage, leading to cancer, and a rapid ageing phenotype. In humans, low expression of Kip1 ubiquitination-promoting complex 1 (KPC1), a ubiquitin ligase required for p105 to p50 processing, was shown to correlate with a reduction in p50 and glioblastoma incidence. Therefore, while the majority of research in this field has focused on the upstream signalling pathways leading to NF-κB activation or the function of other NF-κB subunits, such as RelA (p65), these data demonstrate a critical role for NFKB1, potentially revealing new strategies for targeting this pathway in inflammatory diseases and cancer.
187 citations
References
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TL;DR: A significant age-related increase in nuclear NF-kappa B binding activity together with increased protein levels of p52 and p65 components in rat liver is reported, indicating that the expression level of NF- kappa B genes is not significantly affected by aging.
Abstract: Changes occur in gene expression during aging in vivo and in replicative senescence in vitro, suggesting that aging can affect gene regulation. We have recently observed age-related changes in ubiquitously expressed, oxidative stress-responsive nuclear factor-κB (NF-κB) pathway during aging. Here we report a significant age-related increase in nuclear NF-κB binding activity together with increased protein levels of p52 and p65 components in rat liver. An additional, higher molecular weight protein band seen in their western blots suggests that their post-translational modification (but not phosphorylation) occurs in liver, which might affect their nuclear localization and binding activity during aging. However, aging did not affect the protein levels of the main IκB inhibitors (IκBα and IκBβ) or IκB kinase (IKK)-complex subunits (IKKα, -β, and -γ) involved in NF-κB activation. In addition, the level of Ser32-phosphorylated IκBα was unaffected by age, suggesting that neither the IKK complex nor altered lev...
96 citations
"Loss of Nfkb1 leads to early onset ..." refers background in this paper
...While p50 protein level remains stable with advancing age, p52 increases, a finding also noted in rat liver and gastric mucosa [47, 50]....
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TL;DR: Evidence is provided that NFκB activity plays an important role in protecting the primary auditory neurons from excitotoxic damage and age-related degeneration and a possible mechanism underlying this protection is that the NFκ B activity may help to maintain calcium homeostasis in SGNs.
Abstract: Degeneration of the spiral ganglion neurons (SGNs) of the auditory nerve occurs with age and in response to acoustic injury. Histopathological observations suggest that the neural degeneration often begins with an excitotoxic process affecting the afferent dendrites under the inner hair cells (IHCs), however, little is known about the sequence of cellular or molecular events mediating this excitotoxicity. Nuclear factor κB (NFκB) is a transcription factor involved in regulating inflammatory responses and apoptosis in many cell types. NFκB is also associated with intracellular calcium regulation, an important factor in neuronal excitotoxicity. Here, we provide evidence that NFκB can play a central role in the degeneration of SGNs. Mice lacking the p50 subunit of NFκB (p50−/− mice) showed an accelerated hearing loss with age that was highly associated with an exacerbated excitotoxic-like damage in afferent dendrites under IHCs and an accelerated loss of SGNs. Also, as evidenced by immunostaining intensity, calcium-buffering proteins were significantly elevated in SGNs of the p50−/− mice. Finally, the knock-out mice exhibited an increased sensitivity to low-level noise exposure. The accelerated hearing loss and neural degeneration with age in the p50−/− mice occurred in the absence of concomitant hair cell loss and decline of the endocochlear potential. These results indicate that NFκB activity plays an important role in protecting the primary auditory neurons from excitotoxic damage and age-related degeneration. A possible mechanism underlying this protection is that the NFκB activity may help to maintain calcium homeostasis in SGNs.
94 citations
TL;DR: A histopathologic study of the brains of 96 mice documents an age-associated increase in hypertrophic astrocytes in white matter, distinct from previously reported proliferation of glial cells in the grey matter, and presents an interesting model for the study of aberrant cellular activity and perhaps neurodegeneration, modulated by caloric restriction.
62 citations
"Loss of Nfkb1 leads to early onset ..." refers background in this paper
...While the mechanistic link between GFAP staining and aging remains unclear, a strong correlation between these findings is evident both in rodents and humans [20, 38, 39]....
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...However, given the association between aging and CNS white matter glial fibrillary acidic protein (GFAP) staining [20], we examined GFAP reactivity in these animals....
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TL;DR: The results are consistent with the view that constitutive activation of inflammatory pathways is a phenomenon prevalent in aged fibroblasts, and are possibly part of a cellular survival process in response to compromised mitochondrial function.
Abstract: Chronic inflammation is a well-known corollary of the aging process and is believed to significantly contribute to morbidity and mortality of many age-associated chronic diseases. However, the mechanisms that cause age-associated inflammatory changes are not well understood. Particularly, the contribution of cell stress responses to age-associated inflammation in 'non-inflammatory' cells remains poorly defined. The present cross-sectional study focused on differences in molecular signatures indicative of inflammatory states associated with biological aging of human fibroblasts from donors aged 22 to 92 years. Gene expression profiling revealed elevated steady-state transcript levels consistent with a chronic inflammatory state in fibroblast cell-strains obtained from older donors. We also observed enhanced NF-κB DNA binding activity in a subset of strains, and the NF-κB profile correlated with mRNA expression levels characteristic of inflammatory processes, which include transcripts coding for cytokines, chemokines, components of the complement cascade and MHC molecules. This intrinsic low-grade inflammatory state, as it relates to aging, occurs in cultured cells irrespective of the presence of other cell types or the in vivo context. Our results are consistent with the view that constitutive activation of inflammatory pathways is a phenomenon prevalent in aged fibroblasts. It is possibly part of a cellular survival process in response to compromised mitochondrial function. Importantly, the inflammatory gene expression signature described here is cell autonomous, i.e. occurs in the absence of prototypical immune or pro-inflammatory cells, growth factors, or other inflammatory mediators.
56 citations
"Loss of Nfkb1 leads to early onset ..." refers background in this paper
...Although age-associated increase in overall NF-κB binding has been described [28-30, 46-49], a change in dimer composition has not previously been reported....
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...As previously reported with other tissue [28-30], a general increase in NF-κB DNA binding is evident in brains of old mice compared to young (Supplemental Fig....
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TL;DR: It is shown that p50 endogenously regulates the activity of RelA/p65 by decreasing its phosphoacetylation and DNA binding activity and specific histone modifications and that genetic ablation of p50 leads to air space enlargement in mouse.
Abstract: NF-kappaB-mediated proinflammatory response to cigarette smoke (CS) plays a pivotal role in the pathogenesis of chronic obstructive pulmonary disease (COPD). The heterodimer of RelA/p65-p50 (subunits of NF-kappaB) is involved in transactivation of NF-kappaB-dependent genes, but interestingly p50 has no transactivation domain. The endogenous role of p50 subunit, particularly in regulation of CS-mediated inflammation in vivo, is not known. We therefore hypothesized that p50 subunit plays a regulatory role on RelA/p65, and genetic ablation of p50 (p50(-/-)) leads to increased lung inflammation and lung destruction in response to CS exposure in mouse. To test this hypothesis, p50-knockout and wild-type (WT) mice were exposed to CS for 3 days to 6 mo, and inflammatory responses as well as air space enlargement were assessed. Lungs of p50-deficient mice showed augmented proinflammatory response to acute and chronic CS exposures as evidenced by increased inflammatory cell influx and proinflammatory mediators release such as monocyte chemoattractant protein-1 (MCP-1) and interferon-inducible protein-10 (IP-10) compared with WT mice. IKK2 inhibitor (IMD-0354), which reduces the nuclear translocation of RelA/p65, attenuated CS-mediated neutrophil influx in bronchoalveolar lavage fluid and cytokine (MCP-1 and IP-10) levels in lungs of WT but not in p50-deficient mice. Importantly, p50 deficiency resulted in increased phosphorylation (Ser276 and Ser536), acetylation (Lys310), and DNA binding activity of RelA/p65 in mouse lung, associated with increased chromatin remodeling evidenced by specific phosphoacetylation of histone H3 (Ser10/Lys9) and acetylation of H4 (Lys12) in response to CS exposure. Surprisingly, p50-null mice showed spontaneous air space enlargement, which was further increased after CS exposure compared with WT mice. Thus our data showed that p50 endogenously regulates the activity of RelA/p65 by decreasing its phosphoacetylation and DNA binding activity and specific histone modifications and that genetic ablation of p50 leads to air space enlargement in mouse.
50 citations
"Loss of Nfkb1 leads to early onset ..." refers result in this paper
...Nevertheless, other organs have also been implicated in the premature aging of Nfkb1 mice as exemplified both by our results and the early emphysema and decreased skin thickness noted by others [41, 42]....
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