The accumulation and aggregation of misfolded proteins in the brain, such as amyloid-β (Aβ) and hyperphosphorylated tau, is a neuropathological hallmark of Alzheimer’s disease (AD). Previously, we developed and validated a novel non-human primate model for sporadic AD (sAD) research using intracerebroventricular administration of streptozotocin (icv STZ). To date, no characterization of AD-related genes in different brain regions has been performed. Therefore, in the current study, the expression of seven amyloid precursor protein (APP) pathway-related and five tau phosphorylation-related genes was investigated by quantitative real-time PCR experiments, using two matched-pair brain samples from control and icv STZ-treated cynomolgus monkeys. The genes showed similar expression patterns within the control and icv STZ-treated groups; however, marked differences in gene expression patterns were observed between the control and icv STZ-treated groups. Remarkably, other than β-secretase (BACE1) and cyclin-dependent kinase 5 (CDK5), all the genes tested showed similar expression patterns in AD models compared to controls, with increased levels in the precuneus and occipital cortex. However, significant changes in gene expression patterns were not detected in the frontal cortex, hippocampus, or posterior cingulate. Based on these results, we conclude that APP may be cleaved via the general metabolic mechanisms of increased α- and γ-secretase levels, and that hyperphosphorylation of tau could be mediated by elevated levels of tau protein kinase, specifically in the precuneus and occipital cortex.

Background: Obesity due to an excessive intake of nutrient disturbs the hypothalamus-mediated energy metabolism subsequently develops metabolic disorders. In this study, we investigated the effect of pine needle extract (PNE) on the hypothalamic proopiomelanocortin (POMC) neurons involved in the regulation of energy balance via melanocortin system and fat tissue metabolism. Methods: We performed electrophysiological and immunohistochemical analyses to determine the effect of PNE on POMC neurons. Mice were fed a normal or high-fat diet for 12 weeks, then received PNE for the last 2 weeks to measure the following physiological indices: Body weight, food intake, fat/lean mass, glucose metabolism, and plasma leptin levels. In addition, changes of thermogenic, lipolytic, and lipogenetic markers were evaluated in brown adipose tissue (BAT) and white adipose tissue (WAT) by western blotting, respectively. Results: PNE increased hypothalamic POMC neuronal activity, and the effect was abolished by blockade of melanocortin 3/4 receptors (MC3/4Rs). PNE decreased body weight, fat mass, plasma leptin levels, and improved glucose metabolism after high-fat-induced obesity. However, PNE did not change the expression of thermogenic markers of the BAT in HFD fed groups, but decreased only the lipogenetic markers of WAT. This study suggests that PNE has a potent anti-obesity effect, inhibiting lipogenesis in WAT, even though HFD-induced leptin resistance-mediated disruption of POMC neuronal activity.

The characterization of genomic or epigenomic variation in human and animal models could provide important insight into pathophysiological mechanisms of various diseases, and lead to new developments in disease diagnosis and clinical intervention. The African green monkey (AGM; Chlorocebus aethiops) and cynomolgus monkey (CM; Macaca fascicularis) have long been considered important animal models in biomedical research. However, non-human primate-specific methods applicable to epigenomic analyses in AGM and CM are lacking. The recent development of methyl-capture sequencing (MC-seq) has an unprecedented advantage of cost-effectiveness, and further allows for extending the methylome coverage compared to conventional sequencing approaches. Here, we used a human probe-designed MC-seq method to assay DNA methylation in DNA obtained from 13 CM and three AGM blood samples. To effectively adapt the human probe-designed target region for methylome analysis in non-human primates, we redefined the target regions, focusing on regulatory regions and intragenic regions with consideration of interspecific sequence homology and promoter region variation. Methyl-capture efficiency was controlled by the sequence identity between the captured probes based on the human reference genome and the AGM and CM genome sequences, respectively. Using reasonable guidelines, 56 and 62% of the human-based capture probes could be effectively mapped for DNA methylome profiling in the AGM and CM genome, respectively, according to numeric global statistics. In particular, our method could cover up to 89 and 87% of the regulatory regions of the AGM and CM genome, respectively. Use of human-based MC-seq methods provides an attractive, cost-effective approach for the methylome profiling of non-human primates at the single-base resolution level.

African green monkeys (AGMs, Chlorocebus aethiops) are Old World monkeys which are used as experimental models in biomedical research. Recent technological advances in next generation sequencing are useful for unraveling the genetic mechanisms underlying senescence, aging, and age-related disease. To elucidate the normal aging mechanisms in older age, the blood transcriptomes of nine healthy, aged AGMs (15‒23 years old), were analyzed over two years. We identified 910‒1399 accumulated differentially expressed genes (DEGs) in each individual, which increased with age. Aging-related DEGs were sorted across the three time points. A major proportion of the aging-related DEGs belonged to gene ontology (GO) categories involved in translation and rRNA metabolic processes. Next, we sorted common aging-related DEGs across three time points over two years. Common aging-related DEGs belonged to GO categories involved in translation, cellular component biogenesis, rRNA metabolic processes, cellular component organization, biogenesis, and RNA metabolic processes. Furthermore, we identified 29 candidate aging genes that were upregulated across the time series analysis. These candidate aging genes were linked to protein synthesis. This study describes a changing gene expression pattern in AGMs during aging using longitudinal transcriptome sequencing. The candidate aging genes identified here may be potential targets for the treatment of aging.

Background: Alternative splicing (AS) generates various transcripts from a single gene and thus plays a significant role in transcriptomic diversity and proteomic complexity. Alu elements are primate-specific transposable elements (TEs) and can provide a donor or acceptor site for AS. In a study on TE-mediated AS, we recently identified a novel AluSz6-exonized ACTR8 transcript of the crab-eating monkey (Macaca fascicularis). In the present study, we sought to determine the molecular mechanism of AluSz6 exonization of the ACTR8 gene and investigate its evolutionary and functional consequences in the crab-eating monkey. Results: We performed RT-PCR and genomic PCR to analyze AluSz6 exonization in the ACTR8 gene and the expression of the AluSz6-exonized transcript in nine primate samples, including prosimians, New world monkeys, Old world monkeys, and hominoids. AluSz6 integration was estimated to have occurred before the divergence of simians and prosimians. The Alu-exonized transcript obtained by AS was lineage-specific and expressed only in Old world monkeys and apes, and humans. This lineage-specific expression was caused by a single G duplication in AluSz6, which provides a new canonical 5′ splicing site. We further identified other alternative transcripts that were unaffected by the AluSz6 insertion. Finally, we observed that the alternative transcripts were transcribed into new isoforms with C-terminus deletion, and in silico analysis showed that these isoforms do not have a destructive function. Conclusions: The single G duplication in the TE sequence is the source of TE exonization and AS, and this mutation may suffer a different fate of ACTR8 gene expression during primate evolution.

Despite the different perspectives by diverse research sectors spanning several decades, aging research remains uncharted territory for human beings. Therefore, we investigated the transcriptomic characteristics of eight male healthy cynomolgus macaques, and the annual sampling was designed with two individuals in four age groups. As a laboratory animal, the macaques were meticulously shielded from all environmental factors except aging. The results showed recent findings of certain immune response and the age-associated network of primate immunity. Three important aging patterns were identified and each gene clusters represented a different immune response. The increased expression pattern was predominantly associated with innate immune cells, such as Neutrophils and NK cells, causing chronic inflammation with aging whereas the other two decreased patterns were associated with adaptive immunity, especially “B cell activation” affecting antibody diversity of aging. Furthermore, the hub gene network of the patterns reflected transcriptomic age and correlated with human illness status, aiding in future human disease prediction. Our macaque transcriptome profiling results offer systematic insights into the age-related immunological features of primates.