Time-dependent effects of high-fat diet on cognition and cerebral insulin signaling: Window for recovery and potential therapeutic target.

While high-fat diet (HFD)-induced obesity is a major threat to global public health, the effect of HFD on cognition and insulin signaling during ageing remains controversial. The aim of this study was to characterize the dynamic alterations in cognition and cerebral insulin signaling during 6-month HFD consumption, and to investigate the potential therapeutic target and optimal timing to rescue obesity-related cognitive deficits. In the present study, impaired memory retention induced by 2-month HFD was recovered after 4 months on HFD. Prolonged (6-month) HFD did not further enhance tau hyperphosphorylation and ß-amyloid deposition, which was consistent with the alleviation of memory retention. In brain insulin signaling, 2-month HFD increased IRS-1 and p-IRS-1(Ser307)/IRS-1, while decreasing pAKT(Ser473)/AKT, PI3K and mTOR; 4-month HFD decreased IRS-1 and pAKT(Ser473)/AKT, while increasing AKT; 6-month HFD increased IRS-1, pAKT(Ser473)/AKT, and mTOR, while decreasing p-IRS-1(Ser307)/IRS-1, PI3K and AKT. Notably, bioinformatic analysis revealed a rhythmic process presented only in 4-month HFD group, with Srebf1 emerging as a link between circadian rhythms and insulin signaling pathway. These results suggest that prolonged HFD prevents further cognitive decline and the progression of Alzheimer's disease (AD)-related pathologies during ageing. Moreover, there may be a window for recovery, in which Srebf1 acts as a self-recovery switch to address obesity-related cognitive disorders in elders.

Transcriptome analysis reveals that cyclophosphamide induces premature ovarian failure by blocking cholesterol biosynthesis pathway.

AIMS: The present study aimed to investigate the effects of cyclophosphamide (Cytoxan, CTX) on premature ovarian failure (POF) in mice and its regulatory mechanisms by transcriptome analysis. MAIN METHODS: Female C57BL/6 mice were treated with a single intraperitoneal injection of 70 mg/kg CTX. Serum levels of estradiol (E2) and follicle stimulating hormone (FSH) were measured by enzyme-linked immunosorbent assay (ELISA), and follicular structure differences were observed by hematoxylin and eosin (H&E) staining. The main mechanism of POF was investigated by RNA-seq data, protein-protein interaction (PPI) networks and qPCR analysis. KEY FINDINGS: The serum levels of E2 were significantly decreased and those of FSH were significantly increased compared to the control group. The ovarian weights of the mice in the CTX group were reduced, and abnormal follicular structures were also observed in the CTX group. The RNA-seq data show that the downregulated genes were related to the cholesterol biosynthesis pathway. The PPI network and qPCR analyses further confirm that the PPAR signaling pathway and the ovarian infertility genes were also involved in blocking the cholesterol biosynthesis pathway. The differences were statistically significant. SIGNIFICANCE: Our results indicate that CTX may exert its anti-tumor effects by inactivating the cholesterol biosynthesis pathway, and simultaneously reducing the supply of estrogen precursor materials, ultimately leading to the occurrence of POF. Our data provided a preliminary theoretical basis for resolving the clinical toxicity and side effects of CTX.

miR-17, miR-21, and miR-143 Enhance Adipogenic Differentiation from Porcine Bone Marrow-Derived Mesenchymal Stem Cells.

Bone marrow-derived mesenchymal stem cells (BMSCs) have multilineage differentiation abilities toward adipocytes and osteoblasts. Recently, numerous studies have focused on the roles of microRNAs (miRNAs) in the process of adipogenic differentiation of human and mouse cells. However, the role of miRNAs in adipogenic differentiation process of porcine BMSCs (pBMSCs) remains unclear. In this study, pBMSCs were induced to differentiate into adipocytes using a chemical approach, and the roles of miR-17, miR-21, and miR-143 in this process were investigated. Our results showed that pBMSCs could be chemically induced to differentiate into adipocytes and that the expression of miR-17, miR-21, and miR-143 increased during differentiation. Then, overexpression of mimics of miR-17, miR-21, and miR-143 increased the number of oil red O-positive cells of adipocyte differentiation. The expression levels of CCAAT/enhancer-binding protein alpha (C/EBPα) mRNA showed increases of 1.8-, 1.5-, and 1.2-fold in the groups expressing mimics of miR-21, miR-17, and miR-143, respectively, at day 20. These results demonstrate that miR-17, miR-21, and miR-143 are involved in and promote the adipogenic differentiation of pBMSCs. This study provides an experimental basis for establishing a stable and efficient adipogenic differentiation model for applications in cell therapy and tissue engineering.

Effects of WT1 down-regulation on oocyte maturation and preimplantation embryo development in pigs.

The Wilms' tumour 1 (WT1) gene originally identified as a tumour suppressor associated with WTs encodes a zinc finger-containing transcription factor that is expressed in multiple tissues and is an important regulator of cellular and organ growth, proliferation, development, migration and survival. However, there is a deficiency of data regarding the expression and function of WT1 during oocyte maturation and preimplantation embryonic development. Herein, we sought to define the expression characteristics and functions of WT1 during oocyte maturation and preimplantation embryonic development in pigs. We show that WT1 is expressed in porcine oocytes and at all preimplantation stages in embryos generated by ICSI. We then evaluated the effects of down-regulating WT1 expression at germinal vesicle and early ICSI stages using a recombinant plasmid (pGLV3-WT1-shRNA). Down-regulation of WT1 did not affect oocyte maturation but significantly decreased preimplantation embryonic development and increased apoptosis in blastocysts. These results indicate that WT1 plays important roles in the development of porcine preimplantation embryos.

The generation of transgenic mice with fat1 and fad2 genes that have their own polyunsaturated fatty acid biosynthetic pathway.

BACKGROUND: Microorganisms and higher plants possess their own omega-3 and omega-6 polyunsaturated fatty acid (PUFAs) biosynthetic pathways. The n-6 fatty acid desaturase gene fad-2 codes for the n-6 desaturase enzyme that coverts oleic acid (OA 18:1 n-9) into linoleic acid (LA 18:2 n-6). The n-3 fatty acid desaturase gene fat-1 codes for the n-3 desaturase enzyme that converts n-6 PUFAs into n-3 PUFAs. Mammals lack n-3 and n-6 desaturase enzymes; therefore, they must obtain their omega-3 and omega-6 fatty acids by consuming plants or seafood. The beneficial effects of n-3 and n-6 PUFAs on human development and cardiovascular health have been well documented. METHODS: Here, we generated fat-1 and fad-2 transgenic mice by introducing mammal expression vectors containing the fat-1 and fad-2 genes via microinjection. RESULTS: Seven transgenic mice were obtained that expressed functional n-3 and n-6 desaturase enzymes. Analysis of the fatty acid contents of transgenic mouse livers revealed that n-6 and n-3 PUFA levels were greatly increased in the transgenic mice compared to wild-type mice. The use ratios of n-9 PUFAs (18:1 n-9) and n-6 PUFAs were both greater in the transgenic mice than in the wild-type controls. CONCLUSION: These transgenic mice were capable of producing their own omega-3 and omega-6 fatty acids. They have the same fatty acid metabolic pathways as higher plants and microbes.