NADH dehydrogenase activity and expression of mRNA of complex I (ND1, 51kDa, and 75kDa) in heart mitochondria of klotho mouse

Klotho regulates postnatal neurogenesis and protects against age-related spatial memory loss

Although the absence of the age-regulating klotho protein causes klotho-deficient mice to rapidly develop cognitive impairment and increasing klotho enhances hippocampal-dependent memory, the cellular effects of klotho that mediate hippocampal-dependent memory function are unknown. Here, we show premature aging of the klotho-deficient hippocampal neurogenic niche as evidenced by reduced numbers of neural stem cells, decreased proliferation, and impaired maturation of immature neurons. Klotho-deficient neurospheres show reduced proliferation and size that is rescued by supplementation with shed klotho protein. Conversely, 6-month-old klotho-overexpressing mice exhibit increased numbers of neural stem cells, increased proliferation, and more immature neurons with enhanced dendritic arborization. Protection from normal age-related loss of object location memory with klotho overexpression and loss of spatial memory when klotho is reduced by even half suggests direct, local effects of the protein. Together, these data show that klotho is a novel regulator of postnatal neurogenesis affecting neural stem cell proliferation and maturation sufficient to impact hippocampal-dependent spatial memory function.

Integrating mitochondriomics in children's environmental health

The amount of scientific research linking environmental exposures and childhood health outcomes continues to grow; yet few studies have teased out the mechanisms involved in environmentally-induced diseases. Cells can respond to environmental stressors in many ways: inducing oxidative stress/inflammation, changes in energy production and epigenetic alterations. Mitochondria, tiny organelles that each retains their own DNA, are exquisitely sensitive to environmental insults and are thought to be central players in these pathways. While it is intuitive that mitochondria play an important role in disease processes, given that every cell of our body is dependent on energy metabolism, it is less clear how environmental exposures impact mitochondrial mechanisms that may lead to enhanced risk of disease. Many of the effects of the environment are initiated in utero and integrating mitochondriomics into children's environmental health studies is a critical priority. This review will highlight (i) the importance of exploring environmental mitochondriomics in children's environmental health, (ii) why environmental mitochondriomics is well suited to biomarker development in this context, and (iii) how molecular and epigenetic changes in mitochondria and mitochondrial DNA (mtDNA) may reflect exposures linked to childhood health outcomes.

Melatonin and the theories of aging: a critical appraisal of melatonin's role in antiaging mechanisms

The classic theories of aging such as the free radical theory, including its mitochondria-related versions, have largely focused on a few specific processes of senescence. Meanwhile, numerous interconnections have become apparent between age-dependent changes previously thought to proceed more or less independently. Increased damage by free radicals is not only linked to impairments of mitochondrial function, but also to inflammaging as it occurs during immune remodeling and by release of proinflammatory cytokines from mitotically arrested, DNA-damaged cells that exhibit the senescence-associated secretory phenotype (SASP). Among other effects, SASP can cause mutations in stem cells that reduce the capacity for tissue regeneration or, in worst case, lead to cancer stem cells. Oxidative stress has also been shown to promote telomere attrition. Moreover, damage by free radicals is connected to impaired circadian rhythmicity. Another nexus exists between cellular oscillators and metabolic sensing, in particular to the aging-suppressor SIRT1, which acts as an accessory clock protein. Melatonin, being a highly pleiotropic regulator molecule, interacts directly or indirectly with all the processes mentioned. These influences are critically reviewed, with emphasis on data from aged organisms and senescence-accelerated animals. The sometimes-controversial findings obtained either in a nongerontological context or in comparisons of tumor with nontumor cells are discussed in light of evidence obtained in senescent organisms. Although, in mammals, lifetime extension by melatonin has been rarely documented in a fully conclusive way, a support of healthy aging has been observed in rodents and is highly likely in humans.