Project description:Klotho functions as an aging suppressor, which, in mice, extends lifespan when overexpressed and accelerates development of aging-like phenotypes when disrupted. Klotho is mainly expressed in brain and kidney and is secreted into the serum and CSF. We have previously shown that Klotho is reduced in brains of old monkeys, rats and mice. We further reported the ability of Klotho to enhance oligodendrocyte differentiation and myelination. Here we examined the effects of Klotho on MO3.13, a human oligodendroglioma cell line in order to determine the potential role of Klotho as a tumor suppressor. We show that exogenous Klotho affects the ERK and Akt signaling pathways and decreases the proliferative abilities of MO3.13 cells. Furthermore, microarray analysis of Klotho-treated MO3.13 cells reveals a massive change in gene expression with 80% of the differentially expressed genes being downregulated. Using gene set enrichment analysis we predicted potential transcription factors involved in regulating Klotho-treated MO3.13 cells and found that these cells are highly enriched in the gene sets, that are similarly observed in cancer, cardiovascular disease, stress, aging and hormone-related chemical and genetic perturbations. Since Klotho is downregulated in all brain tumors tested to date, enhancing Klotho has therapeutic potential for treating brain malignancies. 6 Samples
Project description:Klotho functions as an aging suppressor, which, in mice, extends lifespan when overexpressed and accelerates development of aging-like phenotypes when disrupted. Klotho is mainly expressed in brain and kidney and is secreted into the serum and CSF. We have previously shown that Klotho is reduced in brains of old monkeys, rats and mice. We further reported the ability of Klotho to enhance oligodendrocyte differentiation and myelination. Here we examined the effects of Klotho on MO3.13, a human oligodendroglioma cell line in order to determine the potential role of Klotho as a tumor suppressor. We show that exogenous Klotho affects the ERK and Akt signaling pathways and decreases the proliferative abilities of MO3.13 cells. Furthermore, microarray analysis of Klotho-treated MO3.13 cells reveals a massive change in gene expression with 80% of the differentially expressed genes being downregulated. Using gene set enrichment analysis we predicted potential transcription factors involved in regulating Klotho-treated MO3.13 cells and found that these cells are highly enriched in the gene sets, that are similarly observed in cancer, cardiovascular disease, stress, aging and hormone-related chemical and genetic perturbations. Since Klotho is downregulated in all brain tumors tested to date, enhancing Klotho has therapeutic potential for treating brain malignancies.
Project description:Study the role of klotho as a tumor suppressor in colorectal cancer. [abstract] Klotho is an anti-aging transmembrane protein, which can be shed and function as a hormone. Accumulating data indicate klotho as a tumor suppressor in a wide array of malignancies and indicate the subdomain KL1 as the active region of the protein. We aimed to study the role of klotho as a tumor suppressor in colorectal cancer. Bioinformatics analyses of TCGA datasets indicated reduced klotho mRNA levels in human colorectal cancer, along with negative regulation of klotho expression by hypermethylation of the promoter and 1st exon, and hypomethylation of an area within the gene. Overexpression or treatment with klotho or KL1 inhibited proliferation of colorectal cancer cells in vitro. The in vivo activity of klotho and KL1 was examined using two models recapitulating development of tumors in the normal colonic environment of immune-competent mice. Treatment with klotho inhibited formation of colon polyps induced by the carcinogen azoxymethane, and KL1 treatment slowed growth of orthotopically-implanted colorectal tumors. Gene expression array revealed that klotho and KL1 expression enhanced the unfolded protein response (UPR) and this was further established by increased levels of spliced XBP1, GRP78 and phosphorylated eIF2α. Furthermore, attenuation of the UPR partially abrogated klotho tumor suppressor activity. In conclusion, this study indicates klotho as a tumor suppressor in colorectal cancer and identifies, for the first time, the UPR as a pathway mediating klotho activities in cancer. These data suggest that administration of exogenous klotho or KL1 may serve as a novel strategy for prevention and treatment of colorectal cancer.
Project description:Modulating the number of muscle stems cells, called satellite cells, during early postnatal development produces long-term effects on muscle growth. We tested the hypothesis that high expression levels of the anti-aging protein Klotho in early postnatal myogenesis increase satellite cell numbers by influencing the epigenetic regulation of genes that regulate myogenesis. Our findings show that elevated klotho expression caused a transient increase in satellite cell numbers and slowed muscle fiber growth, followed by a period of accelerated muscle growth that resulted in larger fibers. Klotho also transcriptionally down-regulated the H3K27 demethylase Jmjd3, increased H3K27 methylation and decreased expression of genes in the canonical Wnt pathway, which was associated with a significant delay in muscle differentiation. In addition, Klotho stimulation and subsequent Jmjd3 down-regulation produced similar but not additive reductions in the expression of Wnt4, Wnt9a and Wnt10a in myogenic cells, indicating that inhibition occurred through a common pathway. Together, our results identify a novel pathway through which Klotho influences myogenesis by reducing expression of Jmjd3, leading to reductions in the expression of Wnt genes and inhibition of canonical Wnt signaling.
Project description:Mutations of the β-glucuronidase protein α-Klotho have been associated with premature aging, and altered cognitive function. Although highly expressed in specific areas of the brain, Klotho functions in the central nervous system remain unknow. Here, we show that cultured hippocampal neurons respond to insulin and glutamate stimulation by elevating Klotho protein levels. Conversely, AMPA and NMDA antagonism suppress neuronal Klotho expression. We also provide evidence that soluble Klotho enhances astrocytic aerobic glycolysis by hindering pyruvate metabolism through the mitochondria, and stimulating its processing by lactate dehydrogenase. Pharmacological inhibition of FGFR1, Erk phosphorylation, and monocarboxylic acid transporters prevents Klotho-induced lactate release from astrocytes. Taken together these data suggest Klotho is a potential new player in the metabolic coupling between neurons and astrocytes. Neuronal glutamatergic activity and insulin modulation elicit Klotho release, which in turn stimulates astrocytic lactate formation and release. Lactate can then be used by neurons as a metabolic substrate contributing to fulfill their elevated energy requirements.
Project description:Aging is accompanied by a disrupted information flow, which results from accumulation of molecular mistakes. These mistakes ultimately give rise to debilitating disorders such as skeletal muscle wasting, or sarcopenia. To estimate the growing “disorderliness” of the aging muscle system, we employed a statistical physics approach to estimate the state parameter, entropy, as a function of genes associated with hallmarks of aging. Although the most prominent structural and functional alterations were observed in the oldest old mice (27-29 months), we found that the escalating network entropy reached an inflection point at old age (22-24 months). To probe the potential for restoration of molecular “order” and reversal of the sarcopenic phenotype, we overexpressed the longevity protein, a-Klotho. Klotho overexpression modulated genes representing all hallmarks of aging in both old and oldest-old mice. However, whereas Klotho improved strength in old mice, intervention failed to induce a benefit beyond the entropic tipping point.
Project description:We have demonstrated that the circulating extracellular vesicles (EVs) are essential to the beneficial effect of young serum on the skeletal muscle regenerative cascade. Here, we show that infusions of young serum significantly improved age-associated memory deficits, and the effect was abolished after serum depletion of EVs. RNA-seq analysis of the choroid plexus demonstrated EV-mediated effects on genes involved in barrier function and trans-barrier transport. Comparing the differentially expressed genes to the recently published chronological aging clocks revealed a reversal of transcriptomic aging in the choroid plexus. The hippocampal transcriptome demonstrated a significant upregulation of the anti-aging gene Klotho following young serum treatment and an abrogated effect after EV depletion. Subsequent transcriptomic profiling of Klotho knockout and heterozygous mice showed downregulation of genes associated with transport, exocytosis, and lipid transport, while upregulated genes were associated with activated microglia. The results of our study indicate the significance of EVs as vehicles to deliver signals from the periphery to brain and the importance of Klotho in maintaining brain homeostasis.
Project description:Heterochronic blood exchange (HBE) has demonstrated that circulating factors restore youthful features to aged tissues. However, the systemic mediators of those rejuvenating effects remain poorly defined. We show that the beneficial effect of young blood on aged muscle regeneration was diminished when serum was depleted of extracellular vesicles (EVs). Whereas EVs from young animals rejuvenate aged cell bioenergetics and skeletal muscle regeneration, aging shifts EV subpopulation heterogeneity and compromises downstream benefits on recipient cells. Machine learning classifiers revealed that aging shifts the nucleic acid, but not protein, fingerprint of circulating EVs. Alterations in sub-population heterogeneity were accompanied by declines in transcript levels of the pro-longevity protein, α-Klotho, and injection of EVs improved muscle regeneration in a Klotho mRNA-dependent manner. These studies demonstrate that EVs play a key role in the rejuvenating effects of HBE and that Klotho transcripts within EVs phenocopy the effects of young serum on aged skeletal muscle.
Project description:Platelet factors regulate wound healing and also signal from the blood to the brain. However, whether platelet factors modulate cognition, a highly valued and central manifestation of brain function, is unknown. Here, we show that systemic platelet factor 4 (PF4) modulates cognition and its molecular signature. Klotho, a longevity and cognition-enhancing protein, acutely activated platelets and increased circulating platelet factors, most robustly platelet factor 4 (PF4). To directly test PF4 effects on the brain, we treated mice with vehicle or systemic PF4. In young mice, PF4 enhanced synaptic plasticity and cognition. In aging mice, PF4 restored cognitive deficits and rejuvenated a molecular signature of cognition in the aging hippocampus. Augmenting platelet factors such as PF4, a possible messenger of klotho, may enhance cognition in the young brain and rejuvenate cognitive deficits in the aging brain.