The evolution of aging and lifespan

Ca2+/calmodulin signaling in organismal aging and cellular senescence: Impact on human diseases

Molecular mechanisms of aging processes at the level of organisms and cells are in the focus of a large number of research laboratories. This research culminated in recent breakthroughs, which contributed to the better understanding of the natural aging process and aging associated malfunctions leading to age-related diseases. Ca2+ in connection with its master intracellular sensor protein calmodulin (CaM) regulates a plethora of crucial cellular processes orchestrating a wide range of signaling processes. This review focuses on the involvement of Ca2+/CaM in cellular mechanisms, which are associated with normal aging, as well as playing a role in the development of diseases connected with signaling processes during aging. We specifically highlight processes that involve inactivation of proteins, which take part in Ca2+/CaM regulatory systems by oxygen or nitrogen free radical species, during organismal aging and cellular senescence. As examples of organs where aging processes have recently been investigated, we chose to review the literature on molecular aging processes with involvement of Ca2+/CaM in heart and neuronal diseases, as well as in cancer and metabolic diseases, all deeply affected by aging. In addition, this article focuses on cellular senescence, a mechanism that may contribute to aging processes and therefore has been proposed as a target to interfere with the progression of age-associated diseases.

Extensive longevity and DNA virus-driven adaptation in nearctic Myotis bats

The genus Myotis is one of the largest clades of bats, and exhibits some of the most extreme variation in lifespans among mammals alongside unique adaptations to viral tolerance and immune defense. To study the evolution of longevity-associated traits and infectious disease, we generated near-complete genome assemblies and cell lines for 8 closely related species of Myotis. Using genome-wide screens of positive selection, analyses of structural variation, and functional experiments in primary cell lines, we identify new patterns of adaptation contributing to longevity, cancer resistance, and viral interactions in bats. We find that Myotis bats have some of the most significant variation in cancer risk across mammals and demonstrate a unique DNA damage response in primary cells of the long-lived M. lucifugus. We also find evidence of abundant adaptation in response to DNA viruses - but not RNA viruses - in Myotis and other bats in sharp contrast with other mammals, potentially contributing to the role of bats as reservoirs of zoonoses. Together, our results demonstrate how genomics and primary cells derived from diverse taxa uncover the molecular bases of extreme adaptations in non-model organisms.

Risk Factors and Predictive Nomogram for Survival in Elderly Patients with Brain Glioma

OBJECTIVE

To determine the factors that contribute to the survival of elderly individuals diagnosed with brain glioma and develop a prognostic nomogram.

METHODS

Data from elderly individuals (age ≥65 years) histologically diagnosed with brain glioma were sourced from the Surveillance, Epidemiology, and End Results (SEER) database. The dataset was randomly divided into a training cohort and an internal validation cohort at a 6:4 ratio. Additionally, data obtained from Tangdu Hospital constituted an external validation cohort for the study. The identification of independent prognostic factors was achieved through the least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analysis, enabling the construction of a nomogram. Model performance was evaluated using C-index, ROC curves, calibration plot and decision curve analysis (DCA).

RESULTS

A cohort of 20 483 elderly glioma patients was selected from the SEER database. Five prognostic factors (age, marital status, histological type, stage, and treatment) were found to significantly impact overall survival (OS) and cancer-specific survival (CSS), with tumor location emerging as a sixth variable independently linked to CSS. Subsequently, nomogram models were developed to predict the probabilities of survival at 6, 12, and 24 months. The assessment findings from the validation queue indicate a that the model exhibited strong performance.

CONCLUSION

Our nomograms serve as valuable prognostic tools for assessing the survival probability of elderly glioma patients. They can potentially assist in risk stratification and clinical decision-making.

Comparative genomics reveals convergent signals associated with the high metabolism and longevity in birds and bats

Birds and bats have long lifespans relative to their body size compared with non-flying animals. However, the genomic basis associated with longer lifespan of flying species despite their higher metabolism was unclear. In this study, we hypothesized that genes involved in the regulation of metabolism and lifespan changed with the acquisition of flight and searched for genes that show specific evolutionary patterns in flying species. As a result, we identified several genes that show different evolutionary rates in bird and bat lineages. Genes in pathways involved in lifespan regulation were conserved in birds, while they evolved at an accelerated rate in bats. We also searched for genes in which convergent amino acid substitutions occurred in birds and bats and found such substitutions in genes involved in cancer, reactive oxygen species control and immunity. Our study revealed genomic changes associated with the acquisition of flight in birds and bats and suggested that multiple genes involved in the regulation of lifespan and metabolism support both high metabolism and longevity in flying species.

The Evolutionary Interplay of Somatic and Germline Mutation Rates

Novel sequencing technologies are making it increasingly possible to measure the mutation rates of somatic cell lineages. Accurate germline mutation rate measurement technologies have also been available for a decade, making it possible to assess how this fundamental evolutionary parameter varies across the tree of life. Here, we review some classical theories about germline and somatic mutation rate evolution that were formulated using principles of population genetics and the biology of aging and cancer. We find that somatic mutation rate measurements, while still limited in phylogenetic diversity, seem consistent with the theory that selection to preserve the soma is proportional to life span. However, germline and somatic theories make conflicting predictions regarding which species should have the most accurate DNA repair. Resolving this conflict will require carefully measuring how mutation rates scale with time and cell division and achieving a better understanding of mutation rate pleiotropy among cell types.

Single-cell phylotranscriptomics of developmental and cell type evolution

Single-cell phylotranscriptomics is an emerging tool to reveal the molecular and cellular mechanisms of evolution. We summarize its utility in studying the hourglass pattern of ontogenetic evolution and for understanding the evolutionary history of cell types. The developmental hourglass model suggests that the mid-embryonic stage is the most conserved period of development across species, which is supported by morphological and molecular studies. Single-cell phylotranscriptomic analysis has revealed previously underappreciated heterogeneity in transcriptome ages among lineages and cell types throughout development, and has identified the lineages and tissues that drive the whole-organism hourglass pattern. Single-cell transcriptome age analyses also provide important insights into the origin of germ layers, the different selective forces on tissues during adaptation, and the evolutionary relationships between cell types.

Time is ticking faster for long genes in aging

Recent studies of aging organisms have identified a systematic phenomenon, characterized by a negative correlation between gene length and their expression in various cell types, species, and diseases. We term this phenomenon gene-length-dependent transcription decline (GLTD) and suggest that it may represent a bottleneck in the transcription machinery and thereby significantly contribute to aging as an etiological factor. We review potential links between GLTD and key aging processes such as DNA damage and explore their potential in identifying disease modification targets. Notably, in Alzheimer's disease, GLTD spotlights extremely long synaptic genes at chromosomal fragile sites (CFSs) and their vulnerability to postmitotic DNA damage. We suggest that GLTD is an integral element of biological aging.