BackgroundAs the population aging progresses, age-related osteoporosis has become one of the most common and severe chronic degenerative diseases. Due to insufficient understanding of its complex pathomechanisms, current clinical treatments often suffer from many negative effects. Type H vessels play critical role in bone remodeling owing to their specialized function in coupling angiogenesis and osteogenesis. Increasing evidences have shown a close association between the age-related decline of type H vessels and bone loss. However, the underlying mechanisms whereby the regression of type H vessels with aging remain largely unknown.MethodsCol2-Cre ^ERT /Foxo1 ^flox/flox mice and FOXO1 inhibitor (AS1842856) treated adult (6 months) and middle aged (10 months) mice were utilized for evaluating the variations in bone volume, bone microarchitecture and type H vessels through micro-CT scanning analysis, histological staining and immunofluorescence staining. In vitro tube-forming and scratch assays were applied to evaluate the angiogenic capacity of human umbilical vein endothelial cells (HUVECs) exposed to AS1842856 or conditioned culture milieu of Human Brain Vascular Pericytes (HBVPs). The expression of pericyte marker proteins, myofibroblast-related proteins and genes in inhibitors-stimulated HBVPs were detected via western blot analysis and Reverse transcription-quantitative PCR (RT-qPCR). Furthermore, perivascular myofibroblastic-like transformation was confirmed in AS1842856-treated animal models through immunofluorescence staining. We also constructed Adipoq-Cre/Foxo1 ^flox/flox conditional knockout mice and measured their bone mass and type H vessels by micro-CT and immunofluorescence staining. Mechanistic experiments in vitro were conducted via detection of mTOR signalling expression in HBVPs with pharmacological intervention (AS1842856 and rapamycin), genetic knockdown of Foxo1, or FOXO1-overexpression plasmid treatment, verified by RT-qPCR, western blot analysis and cellular immunofluorescence staining. In vivo validation was conducted on Adipoq-Cre/Foxo1 ^flox/flox mice using immunofluorescence staining. Finally, alterations in osteo-morphology and type H vessels were verified in AS1842856-treated and rapamycin-treated aged mouse models.ResultsThis study identified FOXO1 in pericytes as key components for the formation of type H vessels. We found that FOXO1 expression in pericytes decreases with aging, and pharmacological blocking with AS1842856 promoted type H vessels degeneration and increased bone loss in adult and middle-aged mice, while rapamycin prevented the above pathology in middle-aged mice. We further showed that the loss of FOXO1 in Adipoq ⁺ pericytes led to degeneration of type H vessels and bone loss in mice. Mechanistically, the inhibition of FOXO1 by AS1842856 or knockdown of Foxo1 by siRNAs activated mTOR signaling, thereby resulting in the myofibroblastic transformation of pericytes. Furthermore, blocking mTOR signaling by rapamycin rescued the above effects in vitro and in vivo.ConclusionOur findings uncover a hitherto unknown role of FOXO1 in maintaining the phenotype and function of pericytes, thereby promoting formation of type H vessels. This suggests that targeting the FOXO1-mTOR pathway in pericytes could be a potential therapeutic approach to overcome the regression of type H vessels and bone degeneration with aging.The translational potential of this articleOur research uncovers a previously unidentified role of FOXO1 in preserving pericyte characteristics and promoting the development of type H vessels. Future translational research targeting the FOXO1-mTOR pathway in pericytes may provide new strategies for the prevention and treatment of age-related osteoporosis in the clinic.

2024-11-01·Life Sciences

Blockade of forkhead box protein O1 signaling alleviates primary sclerosing cholangitis-induced sarcopenia in mice model

Article

作者: Kim, Jieun ; Kim, Dong-Hyun ; Han, Yong-Hyun ; Park, Jeongho ; Kim, Tae Hyun

AIMSPrimary sclerosing cholangitis (PSC) is a cholestatic liver disease that affects the hepatic bile ducts, leading to hepatic inflammation and fibrosis. PSC can also impact skeletal muscle through the muscle-liver axis, resulting in sarcopenia, a complication characterized by a generalized loss of muscle mass and strength. The underlying mechanisms and therapy of PSC-induced sarcopenia are not well understood, but one potential regulator is the transcription factor forkhead box protein O1 (FOXO1), which is involved in the ubiquitin proteasome system. Thus, the aim of this study is to assess the pharmacological potential of FOXO1 inhibition for treating PSC-induced sarcopenia.MATERIALS AND METHODSTo establish diet-induced PSC model, we provided mice with a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet for 4 weeks. Mice were intramuscularly injected with AS1842856 (AS), a FOXO1 inhibitor, at a dose of 3.5 mg/kg twice a week for last two weeks. C2C12 myotubes with cholic acid (CA) or deoxycholic acid (DCA) were treated with AS.KEY FINDINGSWe observed a decrease in muscle size and performance in DDC-fed mice with upregulated expression of FOXO1 and E3 ligases such as ATROGIN1 and MuRF1. We found that myotube diameter and MyHC protein level were decreased by CA or DCA in C2C12 myotubes, but treatment of AS reversed these reductions. We observed that intramuscular injection of AS effectively mitigates DDC diet-induced sarcopenia in a rodent PSC model.SIGNIFICANCEOur study suggests that a FOXO1 inhibitor could be a potential leading therapeutic drug for relieving PSC-induced sarcopenia.

2024-07-02·Journal of the American Heart Association

P53 Activation Promotes Maturational Characteristics of Pluripotent Stem Cell‐Derived Cardiomyocytes in 3‐Dimensional Suspension Culture Via FOXO‐FOXM1 Regulation

Article

作者: Höfflin, Jens ; Aoyama, Junya ; Shaw, Jeanna Y. ; Lee, Richard T. ; Ricci‐Blair, Elisabeth ; Kreymerman, Alexander ; van den Berg, Daphne ; Zhuo, Zhu ; Elcure Alvarez, Farid ; Eichholtz, Marie ; Bouffard, Aldric H. ; Elwell, Hannah L. T. ; Velayutham, Nivedhitha ; Rüland, Laura ; Rhoades, Seth ; Garbern, Jessica C. ; Sokol, Morgan ; Ho Sui, Shannan ; Rodriguez Carreras, Yago ; Frontini, Sara ; Mancheño Juncosa, Estela ; Ryan, Herb

BackgroundCurrent protocols generate highly pure human induced pluripotent stem cell–derived cardiomyocytes (hiPSC‐CMs) in vitro that recapitulate characteristics of mature in vivo cardiomyocytes. Yet, a risk of arrhythmias exists when hiPSC‐CMs are injected into large animal models. Thus, understanding hiPSC‐CM maturational mechanisms is crucial for clinical translation. Forkhead box (FOX) transcription factors regulate postnatal cardiomyocyte maturation through a balance between FOXO and FOXM1. We also previously demonstrated that p53 activation enhances hiPSC‐CM maturation. Here, we investigate whether p53 activation modulates the FOXO/FOXM1 balance to promote hiPSC‐CM maturation in 3‐dimensional suspension culture.Methods and ResultsThree‐dimensional cultures of hiPSC‐CMs were treated with Nutlin‐3a (p53 activator, 10 μM), LOM612 (FOXO relocator, 5 μM), AS1842856 (FOXO inhibitor, 1 μM), or RCM‐1 (FOXM1 inhibitor, 1 μM), starting 2 days after onset of beating, with dimethyl sulfoxide (0.2% vehicle) as control. P53 activation promoted hiPSC‐CM metabolic and electrophysiological maturation alongside FOXO upregulation and FOXM1 downregulation, in n=3 to 6 per group for all assays. FOXO inhibition significantly decreased expression of cardiac‐specific markers such as TNNT2. In contrast, FOXO activation or FOXM1 inhibition promoted maturational characteristics such as increased contractility, oxygen consumption, and voltage peak maximum upstroke velocity, in n=3 to 6 per group for all assays. Further, by single‐cell RNA sequencing of n=2 LOM612‐treated cells compared with dimethyl sulfoxide, LOM612‐mediated FOXO activation promoted expression of cardiac maturational pathways.ConclusionsWe show that p53 activation promotes FOXO and suppresses FOXM1 during 3‐dimensional hiPSC‐CM maturation. These results expand our understanding of hiPSC‐CM maturational mechanisms in a clinically‐relevant 3‐dimensional culture system.

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