In Vivo Silencing of MicroRNA-132 Reduces Blood Glucose and Improves Insulin Secretion

Dysfunctional insulin secretion is a hallmark of type 2 diabetes (T2D). Interestingly, several islet microRNAs (miRNAs) are upregulated in T2D, including miR-132. We aimed to investigate whether in vivo treatment with antagomir-132 lowers expression of miR-132 in islets thereby improving insulin secretion and lowering blood glucose. Mice injected with antagomir-132 for 24 h, had reduced expression of miR-132 expression in islets, decreased blood glucose, and increased insulin secretion. In isolated human islets treated with antagomir-132, insulin secretion from four of six donors increased. Target prediction coupled with analysis of miRNA-messenger RNA expression in human islets revealed DESI2, ARIH1, SLC25A28, DIAPH1, and FOXA1 to be targets of miR-132 that are conserved in both species. Increased expression of these targets was validated in mouse islets after antagomir-132 treatment. In conclusion, we identified a post-transcriptional role for miR-132 in insulin secretion, and demonstrated that systemic antagomir-132 treatment in mice can be used to improve insulin secretion and reduce blood glucose in vivo. Our study is a first step towards utilizing antagomirs as therapeutic agents to modulate islet miRNA levels to improve beta cell function

Coculturing Human Islets with Proangiogenic Support Cells to Improve Islet Revascularization at the Subcutaneous Transplantation Site

While subcutaneous tissue has been proposed as a clinically relevant site for pancreatic islet transplantation, a major issue of concern remains, which is its poor vascular state. In an effort to overcome this limitation, we present an efficient and reproducible method to form human composite islets (CIs) with proangiogenic cell types in a controlled manner using nonadherent agarose microwell templates. In this study, we assessed the three-dimensional structure, function, and angiogenic potential of human CIs with human mesenchymal stromal cells (hMSCs), with or without human umbilical vein endothelial cells (HUVECs), and preconditioned hMSCs (PC-hMSCs) in EGM-2 under shear stress. Distinct cellular rearrangements could be observed in CIs, but islet functionality was maintained. In vitro angiogenesis assays found significantly enhanced sprout formation in case of CIs. In particular, the number of sprouts emanating from CIs with PC-hMSCs was significantly increased compared to other conditions. Subsequent in vivo assessment confirmed the proangiogenic potential of CIs. However, in contrast to our in vitro angiogenesis assays, CIs with hMSCs and HUVECs exhibited a higher in vivo angiogenic potential compared to control islets or islets combined with hMSCs or PC-hMSCs. These findings highlight the importance and necessity of verifying in vitro studies with in vivo models to reliably predict, in this case, revascularization outcomes. Regardless, we demonstrate here the therapeutic potential of CIs with proangiogenic support cells to enhance islet revascularization at a clinically relevant, although poorly vascularized, transplantation site

Instrumental learning : an animal model for sleep dependent memory enhancement

The relationship between learning and sleep is multifaceted; learning influences subsequent sleep characteristics, which may in turn influence subsequent memory. Studies in humans indicate that sleep may not only prevent degradation of acquired memories, but even enhance performance without further practice. In a rodent instrumental learning task, individual differences occur in how fast rats learn to associate lever pressing with food reward. Rats habitually sleep between learning sessions, and may differ in this respect. The current study assessed if the instrumental leaning paradigm could serve as a model to study sleep-dependent memory enhancement. Male Wistar rats performed 2 sessions of instrumental learning per day for 1-3 days. Electroencephalography was recorded both before and after the sessions. Sleep deprivation (3 h) was applied between the first and second session in a subgroup of rats. Measurements comprised the number of lever presses in each session, slow wave sleep (SWS) duration, Rapid Eye Movement Sleep (REMS) duration and sleep spindles. Baseline sleep parameters were similar for fast and slow learning rats. Task-exposure increased REMS-duration. The increase in REMS-duration was observed specifically after sessions in which learning occurred, but not after a later session. Sleep deprivation during the 3h period between the initial two sessions interfered with performance enhancement, but did not prevent this in all rats. Our considered movement control protocol induced partial sleep deprivation and also interfered with performance enhancement. The classic instrumental learning task provides a practical model for animal studies on sleep-dependent memory enhancement

Instrumental learning : an animal model for sleep dependent memory enhancement

The relationship between learning and sleep is multifaceted; learning influences subsequent sleep characteristics, which may in turn influence subsequent memory. Studies in humans indicate that sleep may not only prevent degradation of acquired memories, but even enhance performance without further practice. In a rodent instrumental learning task, individual differences occur in how fast rats learn to associate lever pressing with food reward. Rats habitually sleep between learning sessions, and may differ in this respect. The current study assessed if the instrumental leaning paradigm could serve as a model to study sleep-dependent memory enhancement. Male Wistar rats performed 2 sessions of instrumental learning per day for 1-3 days. Electroencephalography was recorded both before and after the sessions. Sleep deprivation (3 h) was applied between the first and second session in a subgroup of rats. Measurements comprised the number of lever presses in each session, slow wave sleep (SWS) duration, Rapid Eye Movement Sleep (REMS) duration and sleep spindles. Baseline sleep parameters were similar for fast and slow learning rats. Task-exposure increased REMS-duration. The increase in REMS-duration was observed specifically after sessions in which learning occurred, but not after a later session. Sleep deprivation during the 3h period between the initial two sessions interfered with performance enhancement, but did not prevent this in all rats. Our considered movement control protocol induced partial sleep deprivation and also interfered with performance enhancement. The classic instrumental learning task provides a practical model for animal studies on sleep-dependent memory enhancement

Instrumental learning : an animal model for sleep dependent memory enhancement

The relationship between learning and sleep is multifaceted; learning influences subsequent sleep characteristics, which may in turn influence subsequent memory. Studies in humans indicate that sleep may not only prevent degradation of acquired memories, but even enhance performance without further practice. In a rodent instrumental learning task, individual differences occur in how fast rats learn to associate lever pressing with food reward. Rats habitually sleep between learning sessions, and may differ in this respect. The current study assessed if the instrumental leaning paradigm could serve as a model to study sleep-dependent memory enhancement. Male Wistar rats performed 2 sessions of instrumental learning per day for 1-3 days. Electroencephalography was recorded both before and after the sessions. Sleep deprivation (3 h) was applied between the first and second session in a subgroup of rats. Measurements comprised the number of lever presses in each session, slow wave sleep (SWS) duration, Rapid Eye Movement Sleep (REMS) duration and sleep spindles. Baseline sleep parameters were similar for fast and slow learning rats. Task-exposure increased REMS-duration. The increase in REMS-duration was observed specifically after sessions in which learning occurred, but not after a later session. Sleep deprivation during the 3h period between the initial two sessions interfered with performance enhancement, but did not prevent this in all rats. Our considered movement control protocol induced partial sleep deprivation and also interfered with performance enhancement. The classic instrumental learning task provides a practical model for animal studies on sleep-dependent memory enhancement

Estradiol-driven metabolism in transwomen associates with reduced circulating extracellular vesicle microRNA-224/452

Objective: Sex steroid hormones like estrogens have a key role in the regulation of energy homeostasis and metabolism. In transwomen, gender-affirming hormone therapy like estradiol (in combination with antiandrogenic compounds) could affect metabolism as well. Given that the under lying pathophysiological mechanisms are not fully understood, this study assessed circulating estradiol-driven microRNAs (miRs) in transwomen and their regulation of genes involved in metabolism in mice. Methods: Following plasma miR-sequencing (seq) in a transwomen discovery (n = 20) and validation cohort (n = 30), we identified miR-224 and miR-452. Subsequent systemic silencing of these miRs in male C57Bl/6 J mice (n = 10) was followed by RNA-seq-based gene expression analysis of brown and white adipose tissue in conjunction with mechanistic studies in cultured adipocytes. Results: Estradiol in transwomen lowered plasma miR-224 and -452 carried in extracellular vesicles (EVs) while their systemic silencing in mice and cultured adipocytes increased lipogenesis (white adipose) but reduced glucose uptake and mitochondrial respiration (brown adipose). In white and bro wn adipose tissue, differentially expressed (miR target) genes are associated with lipogenesis (white adipose) and mitochondrial respiration and glucose uptake (brown adipose). Conclusion: This study identified an estradiol-drive post-transcriptional n etwork that could potentially offer a mechanistic understanding of metabolism following gender-affirming estradiol therapy. </p