The molecular circadian clock regulates metabolic processes within the cell, and the alignment of these clocks between tissues is essential for the maintenance of metabolic homeostasis. The ...possibility of misalignment arises from the differential responsiveness of tissues to the environmental cues that synchronize the clock (zeitgebers). Although light is the dominant environmental cue for the master clock of the suprachiasmatic nucleus, many other tissues are sensitive to feeding and fasting. When rhythms of feeding behavior are altered, for example by shift work or the constant availability of highly palatable foods, strong feedback is sent to the peripheral molecular clocks. Varying degrees of phase shift can cause the systemic misalignment of metabolic processes. Moreover, when there is a misalignment between the endogenous rhythms in physiology and environmental inputs, such as feeding during the inactive phase, the body's ability to maintain homeostasis is impaired. The loss of phase coordination between the organism and environment, as well as internal misalignment between tissues, can produce cardiometabolic disease as a consequence. The aim of this review is to synthesize the work on the mechanisms and metabolic effects of circadian misalignment. The timing of food intake is highlighted as a powerful environmental cue with the potential to destroy or restore the synchrony of circadian rhythms in metabolism.
Summary
Female reproductive capacity declines dramatically in the fourth decade of life as a result of an age‐related decrease in oocyte quality and quantity. The primary causes of reproductive aging ...and the molecular factors responsible for decreased oocyte quality remain elusive. Here, we show that aging of the female germ line is accompanied by mitochondrial dysfunction associated with decreased oxidative phosphorylation and reduced Adenosine tri‐phosphate (ATP) level. Diminished expression of the enzymes responsible for CoQ production, Pdss2 and Coq6, was observed in oocytes of older females in both mouse and human. The age‐related decline in oocyte quality and quantity could be reversed by the administration of CoQ10. Oocyte‐specific disruption of Pdss2 recapitulated many of the mitochondrial and reproductive phenotypes observed in the old females including reduced ATP production and increased meiotic spindle abnormalities, resulting in infertility. Ovarian reserve in the oocyte‐specific Pdss2‐deficient animals was diminished, leading to premature ovarian failure which could be prevented by maternal dietary administration of CoQ10. We conclude that impaired mitochondrial performance created by suboptimal CoQ10 availability can drive age‐associated oocyte deficits causing infertility.
Oncogenic Ras mutants, frequently detected in human cancers, are high-priority anticancer drug targets. However, direct inhibition of oncogenic Ras mutants with small molecules has been extremely ...challenging. Here we report the development of a human IgG1 format antibody, RT11, which internalizes into the cytosol of living cells and selectively binds to the activated GTP-bound form of various oncogenic Ras mutants to block the interactions with effector proteins, thereby suppressing downstream signalling and exerting anti-proliferative effects in a variety of tumour cells harbouring oncogenic Ras mutants. When systemically administered, an RT11 variant with an additional tumour-associated integrin binding moiety for tumour tissue targeting significantly inhibits the in vivo growth of oncogenic Ras-mutated tumour xenografts in mice, but not wild-type Ras-harbouring tumours. Our results demonstrate the feasibility of developing therapeutic antibodies for direct targeting of cytosolic proteins that are inaccessible using current antibody technology.
Stomach and intestinal stem cells are located in discrete niches called the isthmus and crypt, respectively. Recent studies have demonstrated a surprisingly conserved role for Wnt signaling in ...gastrointestinal development. Although intestinal stromal cells secrete Wnt ligands to promote stem cell renewal, the source of stomach Wnt ligands is still unclear. Here, by performing single cell analysis, we identify gastrointestinal stromal cell populations with transcriptome signatures that are conserved between the stomach and intestine. In close proximity to epithelial cells, these perictye-like cells highly express telocyte and pericyte markers as well as Wnt ligands, and they are enriched for Hh signaling. By analyzing mice activated for Hh signaling, we show a conserved mechanism of GLI2 activation of Wnt ligands. Moreover, genetic inhibition of Wnt secretion in perictye-like stromal cells or stromal cells more broadly demonstrates their essential roles in gastrointestinal regeneration and development, respectively, highlighting a redundancy in gastrointestinal stem cell niches.
Transgenic expression of just four defined transcription factors (c-Myc, Klf4, Oct4 and Sox2) is sufficient to reprogram somatic cells to a pluripotent state. The resulting induced pluripotent stem ...(iPS) cells resemble embryonic stem cells in their properties and potential to differentiate into a spectrum of adult cell types. Current reprogramming strategies involve retroviral, lentiviral, adenoviral and plasmid transfection to deliver reprogramming factor transgenes. Although the latter two methods are transient and minimize the potential for insertion mutagenesis, they are currently limited by diminished reprogramming efficiencies. piggyBac (PB) transposition is host-factor independent, and has recently been demonstrated to be functional in various human and mouse cell lines. The PB transposon/transposase system requires only the inverted terminal repeats flanking a transgene and transient expression of the transposase enzyme to catalyse insertion or excision events. Here we demonstrate successful and efficient reprogramming of murine and human embryonic fibroblasts using doxycycline-inducible transcription factors delivered by PB transposition. Stable iPS cells thus generated express characteristic pluripotency markers and succeed in a series of rigorous differentiation assays. By taking advantage of the natural propensity of the PB system for seamless excision, we show that the individual PB insertions can be removed from established iPS cell lines, providing an invaluable tool for discovery. In addition, we have demonstrated the traceless removal of reprogramming factors joined with viral 2A sequences delivered by a single transposon from murine iPS lines. We anticipate that the unique properties of this virus-independent simplification of iPS cell production will accelerate this field further towards full exploration of the reprogramming process and future cell-based therapies.
The features and regulation of uterine angiogenesis and vascular remodelling during pregnancy are poorly defined. Here we show that dynamic and variable decidual angiogenesis (sprouting, ...intussusception and networking), and active vigorous vascular remodelling such as enlargement and elongation of ‘vascular sinus folding’ (VSF) and mural cell drop‐out occur distinctly in a spatiotemporal manner in the rapidly growing mouse uterus during early pregnancy — just after implantation but before placentation. Decidual angiogenesis is mainly regulated through VEGF‐A secreted from the progesterone receptor (PR)‐expressing decidual stromal cells which are largely distributed in the anti‐mesometrial region (AMR). In comparison, P4‐PR‐regulated VEGF‐A‐VEGFR2 signalling, ligand‐independent VEGFR3 signalling and uterine natural killer (uNK) cells positively and coordinately regulate enlargement and elongation of VSF. During the postpartum period, Tie2 signalling could be involved in vascular maturation at the endometrium in a ligand‐independent manner, with marked reduction of VEGF‐A, VEGFR2 and PR expressions. Overall, we show that two key vascular growth factor receptors — VEGFR2 and Tie2 — strikingly but differentially regulate decidual angiogenesis and vascular remodelling in rapidly growing and regressing uteri in an organotypic manner.
VEGFR2 and Tie2 differentially regulate decidual angiogenesis and vascular remodelling in rapidly growing and regressing uteri, questioning the use of treatments affecting these pathways during pregnancy and postpartum.
Obesity is strongly and independently associated with an increased risk of severe illness and death from coronavirus disease 2019 (COVID-19). The pathophysiological changes that result from elevated ...body weight lead to metabolic dysfunction, chronic inflammation, impaired immunological responses, and multisystem disorders, which increase vulnerability to severe illness from COVID-19. While vaccination strategies are under way across the world, the second and third waves of the pandemic, along with the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains, continue to threaten the stability of medical systems worldwide. Furthermore, evidence from previous pandemics suggests that vaccines are less effective in obese individuals than in their healthy-weight counterparts over the long term. Therefore, a consideration of lifestyle changes that can boost metabolic health and immunity is critical to reduce the risk of complications and severe illness from viral infection. In this review, we discuss the potential mechanisms linking excess body weight with COVID-19 morbidity. We also present evidence that intermittent fasting (IF), a dietary program that has gained popularity in recent years, may be an effective strategy to improve metabolic health and immunity and thus reduce the impact of obesity on COVID-19 morbidity and mortality.
Obesity is a strong risk factor for severe illness and mortality from coronavirus disease 2019 (COVID-19) infection. Mechanisms linking obesity with severe COVID-19 include diabetes-associated hyperglycemia, inflammation, weakened immune function, and metabolic dysfunction.Obese populations have a known history of poor response to vaccination and it is unknown whether this will also affect their vaccine-induced immunity to COVID-19. Therefore, it is important to implement dietary and lifestyle changes that potentially boost metabolic and immune health to mitigate the impacts of COVID-19.Intermittent fasting (IF) is associated with weight loss, improved glucose homeostasis, metabolic health restoration, and strengthened immune responses.Amid COVID-19 lockdowns, which are associated with more-sedentary lifestyles, the incorporation of IF may be a practical way to curb unhealthy eating habits, maximize healthy lifestyles, and improve mood and emotional well-being.
The potential benefits and risks of the use of dual antiplatelet therapy beyond a 12-month period in patients receiving drug-eluting stents have not been clearly established.
In two trials, we ...randomly assigned a total of 2701 patients who had received drug-eluting stents and had been free of major adverse cardiac or cerebrovascular events and major bleeding for a period of at least 12 months to receive clopidogrel plus aspirin or aspirin alone. The primary end point was a composite of myocardial infarction or death from cardiac causes. Data from the two trials were merged for analysis.
The median duration of follow-up was 19.2 months. The cumulative risk of the primary outcome at 2 years was 1.8% with dual antiplatelet therapy, as compared with 1.2% with aspirin monotherapy (hazard ratio, 1.65; 95% confidence interval CI, 0.80 to 3.36; P=0.17). The individual risks of myocardial infarction, stroke, stent thrombosis, need for repeat revascularization, major bleeding, and death from any cause did not differ significantly between the two groups. However, in the dual-therapy group as compared with the aspirin-alone group, there was a nonsignificant increase in the composite risk of myocardial infarction, stroke, or death from any cause (hazard ratio, 1.73; 95% CI, 0.99 to 3.00; P=0.051) and in the composite risk of myocardial infarction, stroke, or death from cardiac causes (hazard ratio, 1.84; 95% CI, 0.99 to 3.45; P=0.06).
The use of dual antiplatelet therapy for a period longer than 12 months in patients who had received drug-eluting stents was not significantly more effective than aspirin monotherapy in reducing the rate of myocardial infarction or death from cardiac causes. These findings should be confirmed or refuted through larger, randomized clinical trials with longer-term follow-up. (ClinicalTrials.gov numbers, NCT00484926 and NCT00590174.)
Vascular endothelial growth factor A (VEGF) is highly expressed in adipose tissue. Its role, however, has not been fully elucidated. Here, we reveal the metabolic role of adipose-VEGF by studying ...mice with deletion (VEGFAdΔ) or doxycycline-inducible overexpression of a VEGF transgene (VEGFAdTg) in the adipose tissue. VEGFAdΔ mice have reduced adipose vascular density and show adipose hypoxia, apoptosis, inflammation, and metabolic defects on a high-fat diet. In contrast, induction of VEGF expression in VEGFAdTg mice leads to increased adipose vasculature and reduced hypoxia. The latter changes are sufficient to counteract an established compromising effect of high-fat diet on the metabolism, indicating that metabolic misbalance is reversible by adipose vessel density increase. Our data clearly show the essential role of VEGF signaling for adequate adipose function. Besides revealing insights into the molecular mechanisms of obesity-related metabolic diseases, this study points to the therapeutic potential of increased adipose angiogenesis.
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► Two-way modulations of adipose VEGF were generated with aP2-Cre transgene ► Adipose VEGF KO reduces vasculature, increases hypoxia and inflammation in fat ► Adipose VEGF KO accelerates the development of metabolic disease in high-fat diet ► Induced adipose VEGF has opposite effect on fat and restores metabolic homeostasis
Somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs) by expression of defined embryonic factors. However, little is known of the molecular mechanisms underlying the ...reprogramming process. Here we explore somatic cell reprogramming by exploiting a secondary mouse embryonic fibroblast model that forms iPSCs with high efficiency upon inducible expression of Oct4, Klf4, c-Myc, and Sox2. Temporal analysis of gene expression revealed that reprogramming is a multistep process that is characterized by initiation, maturation, and stabilization phases. Functional analysis by systematic RNAi screening further uncovered a key role for BMP signaling and the induction of mesenchymal-to-epithelial transition (MET) during the initiation phase. We show that this is linked to BMP-dependent induction of miR-205 and the miR-200 family of microRNAs that are key regulators of MET. These studies thus define a multistep mechanism that incorporates a BMP-miRNA-MET axis during somatic cell reprogramming.
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► Temporal gene expression reveals three phases during somatic cell reprogramming ► Mesenchymal-to-epithelial transition (MET) is a hallmark of the initiation phase ► RNAi screening defines MET and BMP signaling as essential for reprogramming ► BMP induces miR-200 family miRNAs to drive MET and somatic cell reprogramming
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