Proliferation Of Adult Stem Cells Research Articles

Serum Induces the Subunit-Specific Activation of NF-κB in Proliferating Human Cardiac Stem Cells.

Cardiovascular diseases (CVDs) are often linked to ageing and are the major cause of death worldwide. The declined proliferation of adult stem cells in the heart often impedes its regenerative potential. Thus, an investigation of the proliferative potential of adult human cardiac stem cells (hCSCs) might be of great interest for improving cell-based treatments of cardiovascular diseases. The application of human blood serum was already shown to enhance hCSC proliferation and reduce senescence. Here, the underlying signalling pathways of serum-mediated hCSC proliferation were studied. We are the first to demonstrate the involvement of the transcription factor NF-κB in the serum-mediated proliferative response of hCSCs by utilizing the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC). RNA-Sequencing (RNA-Seq) revealed ATF6B, COX5B, and TNFRSF14 as potential targets of NF-κB that are involved in serum-induced hCSC proliferation.

Inhibition of HDAC8 Reduces the Proliferation of Adult Neural Stem Cells in the Subventricular Zone.

In the adult mammalian brain, neurons are produced from neural stem cells (NSCs) residing in two niches-the subventricular zone (SVZ), which forms the lining of the lateral ventricles, and the subgranular zone in the hippocampus. Epigenetic mechanisms contribute to maintaining distinct cell fates by suppressing gene expression that is required for deciding alternate cell fates. Several histone deacetylase (HDAC) inhibitors can affect adult neurogenesis in vivo. However, data regarding the role of specific HDACs in cell fate decisions remain limited. Herein, we demonstrate that HDAC8 participates in the regulation of the proliferation and differentiation of NSCs/neural progenitor cells (NPCs) in the adult mouse SVZ. Specific knockout of Hdac8 in NSCs/NPCs inhibited proliferation and neural differentiation. Treatment with the selective HDAC8 inhibitor PCI-34051 reduced the neurosphere size in cultures from the SVZ of adult mice. Further transcriptional datasets revealed that HDAC8 inhibition in adult SVZ cells disturbs biological processes, transcription factor networks, and key regulatory pathways. HDAC8 inhibition in adult SVZ neurospheres upregulated the cytokine-mediated signaling and downregulated the cell cycle pathway. In conclusion, HDAC8 participates in the regulation of in vivo proliferation and differentiation of NSCs/NPCs in the adult SVZ, which provides insights into the underlying molecular mechanisms.

The zinc finger protein CG12744 regulates intestinal stem cells in aged Drosophila through the EGFR and BMP pathways

AimAging is a process characterized by a time-dependent decline in the functionality of adult stem cells and is closely associated with age-related diseases. However, understanding how aging promotes disease and its underlying causes is critical for combating aging. Main methodsThe offspring of UAS-Gal4 and CG12744RNAiDrosophila were cultured for 33 days to evaluate the role of CG12744 in the aging intestine. Immunofluorescence was performed to detect specific cell type markers for assessing proliferation and differentiation. qRT–PCR was used to observe the changes in signaling regulating intestinal homeostasis in the aging intestine after CG12744 knockdown. 16S rRNA-seq analysis was also conducted to elucidate the role of gut microbes in CG12744-mediated intestinal dysfunction. Key findingsThe mRNA levels of CG12744 were significantly increased in the aged midguts. Knockdown of CG12744 in progenitor cells further exacerbates the age-related intestinal hyperplasia and dysfunction. In particular, upon depletion of CG12744 in progenitors, enteroblasts (EBs) exhibited an increased propensity to differentiate along the enteroendocrine cell (EE) lineage. In contrast, the overexpression of CG12744 in progenitor cells restrained age-related gut hyperplasia in Drosophila. Moreover, CG12744 prevented age-related intestinal stem cell (ISC) overproliferation and differentiation by modulating the EGFR, JNK, and BMP pathways. In addition, the inhibition of CG12744 resulted in a significant increase in the gut microbial composition in aging flies. SignificanceThis study established a role for the CG12744 in regulating the proliferation and differentiation of adult stem cells, thereby identifying a potential therapeutic target for diseases caused by age-related dysfunction stem cell dysfunction.

Ketogenic diet attenuates cognitive dysfunctions induced by hypoglycemia via inhibiting endoplasmic reticulum stress-dependent pathways.

Hypoglycemia can potentially cause severe damage to the central nervous system. The ketogenic diet (KD), characterized by high-fat and extremely low-carbohydrate content, can modulate homeostasis and nutrient metabolism, thereby influencing body health. However, the effects and underlying mechanisms of KD on hypoglycemia-induced brain injury have not been thoroughly investigated. We aimed to explore the modulating effects of KD on cognitive functions and elucidate the underlying mechanisms. In this study, one-month-old mice were fed with KD for 2 weeks, and the changes in the gut microbiota were detected using the 16S rRNA gene amplicon sequencing method. The hypoglycemic model of mice was established using insulin, and the potential protective effect of KD on hypoglycemia-induced brain injury in mice was evaluated through immunofluorescence staining, western blotting, transmission electron microscopy, and Golgi staining. Our results showed that the intestinal flora of Dorea increased and Rikenella decreased in KD-fed mice. KD can not only alleviate anxiety-like behavior induced by hypoglycemia, but also increase the proportion of mushroom dendritic spines in the hippocampus by modulating changes in the gut microbiota. KD regulated synaptic plasticity by increasing the levels of SPN, PSD95, and SYP, which relieve cognitive impairment caused by hypoglycemia. Moreover, KD can promote the proliferation and survival of adult neural stem cells in the hippocampus, while reducing apoptosis by suppressing the activation of the IRE1-XBP1 and ATF6 endoplasmic reticulum stress pathways in mice with hypoglycemia. This study provides new evidence for demonstrating that KD may alleviate cognitive dysfunctions caused by hypoglycemia by modulating the gut microbiota.

Differential contribution of TrkB and p75NTR to BDNF-dependent self-renewal, proliferation, and differentiation of adult neural stem cells.

Alterations in adult neurogenesis are a common hallmark of neurodegenerative diseases. Therefore, understanding the molecular mechanisms that control this process is an indispensable requirement for designing therapeutic interventions addressing neurodegeneration. Neurotrophins have been implicated in multiple functions including proliferation, survival, and differentiation of the neural stem cells (NSCs), thereby being good candidates for therapeutic intervention. Brain-derived neurotrophic factor (BDNF) belongs to the neurotrophin family and has been proven to promote neurogenesis in the subgranular zone. However, the effects of BDNF in the adult subventricular zone (SVZ) still remain unclear due to contradictory results. Using in vitro cultures of adult NSCs isolated from the mouse SVZ, we show that low concentrations of BDNF are able to promote self-renewal and proliferation in these cells by activating the tropomyosin-related kinase B (TrkB) receptor. However, higher concentrations of BDNF that can bind the p75 neurotrophin receptor (p75NTR) potentiate TrkB-dependent self-renewal and proliferation and promote differentiation of the adult NSCs, suggesting different molecular mechanisms in BDNF-promoting proliferation and differentiation. The use of an antagonist for p75NTR reduces the increment in NSC proliferation and commitment to the oligodendrocyte lineage. Our data support a fundamental role for both receptors, TrkB and p75NTR, in the regulation of NSC behavior.

Bexarotene drives the self-renewing proliferation of adult neural stem cells, promotes neuron-glial fate shift, and regulates late neuronal differentiation.

Treatment with bexarotene, a selective retinoid X receptor (RXR) agonist, significantly improves behavioral dysfunctions in various neurodegenerative animal models. Additionally, it activates neurodevelopmental and plasticity pathways in the brains of adult mice. Our objective was to investigate the impact of RXR activation by bexarotene on adult neural stem cells (aNSC) and their cell lineages. To achieve this, we treated NSCs isolated from the subventricular zone (SVZ) of adult rat brains from the proliferative stage to the differentiated status. The results showed that bexarotene-treated aNSC exhibited increased BrdU incorporation, SOX2+ dividing cell pairs, and cell migration from neurospheres, revealing that the treatment promotes self-renewing proliferation and cell motility in SVZ-aNCS. Furthermore, bexarotene induced a cell fate shift characterized by a significant increase in GFAP+/S100B+ differentiated astrocytes, which uncovers the participation of activated-RXR in astrogenesis. In the neuronal lineage, the fate shift was counteracted by bexarotene-induced enhancement of NeuN+ nuclei together with neurite network outgrowth, indicating that the RXR agonist stimulates SVZ-aNCS neuronal differentiation at later stages. These findings establish new connections between RXR activation, astro- and neurogenesis in the adult brain, and contribute to the development of therapeutic strategies targeting nuclear receptors for neural repair.

Plant Cellulose as a Substrate for 3D Neural Stem Cell Culture.

Neural stem cell (NSC)-based therapies are at the forefront of regenerative medicine strategies for various neural defects and injuries such as stroke, traumatic brain injury, and spinal cord injury. For several clinical applications, NSC therapies require biocompatible scaffolds to support cell survival and to direct differentiation. Here, we investigate decellularized plant tissue as a novel scaffold for three-dimensional (3D), in vitro culture of NSCs. Plant cellulose scaffolds were shown to support the attachment and proliferation of adult rat hippocampal neural stem cells (NSCs). Further, NSCs differentiated on the cellulose scaffold had significant increases in their expression of neuron-specific beta-III tubulin and glial fibrillary acidic protein compared to 2D culture on a polystyrene plate, indicating that the scaffold may enhance the differentiation of NSCs towards astrocytic and neuronal lineages. Our findings suggest that plant-derived cellulose scaffolds have the potential to be used in neural tissue engineering and can be harnessed to direct the differentiation of NSCs.

Short C-terminal Musashi-1 proteins regulate pluripotency states in embryonic stem cells

The RNA-binding protein Musashi-1 (MSI1) regulates the proliferation and differentiation of adult stem cells. However, its role in embryonic stem cells (ESCs) and early embryonic development remains poorly understood. Here, we report the presence of short C-terminal MSI1 (MSI1-C) proteins in early mouse embryos and mouse ESCs, but not in human ESCs, under conventional culture conditions. In mouse embryos and mESCs, deletion of MSI1-C together with full-length MSI1 causes early embryonic developmental arrest and pluripotency dissolution. MSI1-C is induced upon naive induction and facilitates hESC naive pluripotency acquisition, elevating the pluripotency of primed hESCs toward a formative-like state. MSI1-C proteins are nuclear localized and bind to RNAs involved in DNA-damage repair (including MLH1, BRCA1, and MSH2), conferring on hESCs better survival in human-mouse interspecies cell competition and prolonged ability to form blastoids. This study identifies MSI1-C as an essential regulator in ESC pluripotency states and early embryonic development.

Differentially expressed chaperone genes reveal a stress response required for unidirectional regeneration in the basal chordate Ciona

BackgroundUnidirectional regeneration in the basal chordate Ciona intestinalis involves the proliferation of adult stem cells residing in the branchial sac vasculature and the migration of progenitor cells to the site of distal injury. However, after the Ciona body is bisected, regeneration occurs in the proximal but not in the distal fragments, even if the latter include a part of the branchial sac with stem cells. A transcriptome was sequenced and assembled from the isolated branchial sacs of regenerating animals, and the information was used to provide insights into the absence of regeneration in distal body fragments.ResultsWe identified 1149 differentially expressed genes, which were separated into two major modules by weighted gene correlation network analysis, one consisting of mostly upregulated genes correlated with regeneration and the other consisting of only downregulated genes associated with metabolism and homeostatic processes. The hsp70, dnaJb4, and bag3 genes were among the highest upregulated genes and were predicted to interact in an HSP70 chaperone system. The upregulation of HSP70 chaperone genes was verified and their expression confirmed in BS vasculature cells previously identified as stem and progenitor cells. siRNA-mediated gene knockdown showed that hsp70 and dnaJb4, but not bag3, are required for progenitor cell targeting and distal regeneration. However, neither hsp70 nor dnaJb4 were strongly expressed in the branchial sac vasculature of distal fragments, implying the absence of a stress response. Heat shock treatment of distal body fragments activated hsp70 and dnaJb4 expression indicative of a stress response, induced cell proliferation in branchial sac vasculature cells, and promoted distal regeneration.ConclusionsThe chaperone system genes hsp70, dnaJb4, and bag3 are significantly upregulated in the branchial sac vasculature following distal injury, defining a stress response that is essential for regeneration. The stress response is absent from distal fragments, but can be induced by a heat shock, which activates cell division in the branchial sac vasculature and promotes distal regeneration. This study demonstrates the importance of a stress response for stem cell activation and regeneration in a basal chordate, which may have implications for understanding the limited regenerative activities in other animals, including vertebrates.

Static Magnetic Fields Promote Generation of Muscle Lineage Cells from Pluripotent Stem Cells and Myoblasts.

Static magnetic fields (SMFs) exhibit numerous biological effects and regulate the proliferation and differentiation of several adult stem cells. However, the role of SMFs in the self-renewal maintenance and developmental potential of pluripotent embryonic stem cells (ESCs) remains largely uninvestigated. Here, we show that SMFs promote the expression of the core pluripotent markers Sox2 and SSEA-1. Furthermore, SMFs facilitate the differentiation of ESCs into cardiomyocytes and skeletal muscle cells. Consistently, transcriptome analysis reveals that muscle lineage differentiation and skeletal system specification of ESCs are remarkably strengthened by SMF stimuli. Additionally, when treated with SMFs, C2C12 myoblasts exhibit an increased proliferation rate, improved expression of skeletal muscle markers and elevated myogenic differentiation capacity compared with control cells. Together, our data show that SMFs effectively promote muscle cell generation from pluripotent stem cells and myoblasts. The noninvasive and convenient physical stimuli can be used to increase the production of muscle cells in regenerative medicine and the manufacture of cultured meat in cellular agriculture.

How and why the circadian clock regulates proliferation of adult epithelial stem cells.

First described in the early 20 th century, diurnal oscillations in stem cell proliferation exist in multiple internal epithelia, including in the gastrointestinal track, and in the epidermis. In the mouse epidermis, 3- to 4-fold more stem cells are in S-phase during the night than during the day. Work that is more recent showed that an intact circadian clock intrinsic to keratinocytes is required for these oscillations in epidermal stem cell proliferation. The circadian clock also regulates DNA excision repair and DNA-damage in epidermal stem cells in response to ultraviolet B radiation. During skin inflammation, epidermal stem cell proliferation is increased and diurnal oscillations are suspended. Here we discuss possible reasons for the evolution of this stem cell phenomenon. We argue that the circadian clock coordinates intermediary metabolism and the cell cycle in epidermal stem cells to minimize accumulation of DNA damage from metabolism-generated reactive oxygen species. Circadian disruption, common in modern society, leads to asynchrony between metabolism and the cell cycle, and we speculate this will lead to oxidative DNA damage, dysfunction of epidermal stem cells, and skin aging.

Adult hippocampal neurogenesis in Alzheimer's disease: A roadmap to clinical relevance.

Adult hippocampal neurogenesis (AHN) drops sharply during early stages of Alzheimer's disease (AD), via unknown mechanisms, and correlates with cognitive status in AD patients. Understanding AHN regulation in AD could provide a framework for innovative pharmacological interventions. We here combine molecular, behavioral, and clinical data and critically discuss the multicellular complexity of the AHN niche in relation to AD pathophysiology. We further present a roadmap toward a better understanding of the role of AHN in AD by probing the promises and caveats of the latest technological advancements in the field and addressing the conceptual and methodological challenges ahead.

Imp interacts with Lin28 to regulate adult stem cell proliferation in the Drosophila intestine.

Stem cells are essential for the development and long-term maintenance of tissues and organisms. Preserving tissue homeostasis requires exquisite control of all aspects of stem cell function: cell potency, proliferation, fate decision and differentiation. RNA binding proteins (RBPs) are essential components of the regulatory network that control gene expression in stem cells to maintain self-renewal and long-term homeostasis in adult tissues. While the function of many RBPs may have been characterized in various stem cell populations, how these interact and are organized in genetic networks remains largely elusive. In this report, we show that the conserved RNA binding protein IGF2 mRNA binding protein (Imp) is expressed in intestinal stem cells (ISCs) and progenitors in the adult Drosophila midgut. We demonstrate that Imp is required cell autonomously to maintain stem cell proliferative activity under normal epithelial turnover and in response to tissue damage. Mechanistically, we show that Imp cooperates and directly interacts with Lin28, another highly conserved RBP, to regulate ISC proliferation. We found that both proteins bind to and control the InR mRNA, a critical regulator of ISC self-renewal. Altogether, our data suggests that Imp and Lin28 are part of a larger gene regulatory network controlling gene expression in ISCs and required to maintain epithelial homeostasis.

Abstract 5574: In vivo characterization of a novel CAR-T cell therapy directed towards LGR5 for the treatment of colorectal cancer

Abstract Colorectal cancer (CRC) is the third most diagnosed cancer and incidence rates are rapidly increasing among young adults. Despite current treatments, the 5-year survival rate is approximately 65%, highlighting an urgent need for new therapies. Leucine-rich repeat-containing G-protein coupled receptor (LGR5) is a promising antigen target for chimeric antigen receptor (CAR)-T cell therapy, which may represent a novel effective treatment for CRC. LGR5 binds R-spondins and functions to enhance Wnt and β-catenin signalling involved in maintenance and proliferation of adult stem cells. Expression of LGR5 has been previously reported on cancer stem cells in CRC, and has been demonstrated to play a crucial role in CRC tumor initiation and metastasis. Flow cytometric analysis of LGR5 cell surface expression on in vitro and ex vivo human CRC tumour cells revealed a subpopulation of LGR5+ cells. Six LGR5-targetting CD3+ CAR-T cell variants were developed, which differed in CAR variable heavy (VH) and variable light (VL) chain orientation and hinge length. As preliminary experimentation identified that four of the six CAR-T cell variants displayed robust anti-tumour cytotoxicity in vitro, these CAR-T cell variants were tested for in vivo anti-tumour efficacy using a subcutaneous human colorectal tumor xenograft mouse model. Pre-injection phenotyping after freeze-thawing of the CAR-T cells revealed greater than 94% transduction efficiency, low expression of co-inhibitory receptors CTLA-4 and PD-1 and a high frequency of central memory T cells (CD62L+ CD45RO+). Additionally, a high frequency of the CD8+ compartment of these CAR-T cells expressed perforin, CD107a, Granzyme B and TNFα. For each variant, intravenous injection of 20x106 LGR5-targeting CAR-T cells induced significant tumor regression and gave 100-day survival post-tumor injection. Ex vivo analyses of tumors and spleens via flow cytometry at endpoint indicated CAR-T cell persistence to 100-days post-tumor injection. Of the CAR-T cells isolated from tumours ex vivo, high level expression of co-inhibitory receptors PD-1, CTLA-4, and TIM-3 was observed. The splenic T cell population was enriched for central memory T cells and expressed high levels of PD-1. Complete tumor remission was achieved in 100% of mice receiving the VH-VL orientation, medium hinge CAR construct (designated CNA3103), prompting further investigation of this variant. Intravenous injection of 5x106 CNA3103 CAR-T cells was sufficient to induce tumour remission and 100-day survival. Similarly, complete tumour rejection was achieved with a dose of 2.5x106 CNA3103 CAR-T cells in a 30-day in vivo experiment. These results demonstrate that LGR5-targeting CAR-T cells exhibit potent in vivo anti-tumor efficacy and position LGR5 as a promising CAR target antigen, prompting investigation of LGR5-targeting CAR-T cells as a therapeutic for CRC in future clinical trials. Citation Format: Dylan J. McPeake, Timona S. Tyllis, Jade Foeng, Veronika Bandara, Caitlin A. Abbott, Batjargal Gundsambuu, Elaheh Rohani-Rad, Silvana Napoli, Timothy Sadlon, Simon C. Barry, Shaun R. McColl. In vivo characterization of a novel CAR-T cell therapy directed towards LGR5 for the treatment of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5574.

Glutamine metabolism co‐ordinates the cell‐cycle with cell fate in stem cells

Activation of stem cell proliferation is a critical event in tissue regeneration. The metabolic switch in adult stem cells from the oxidative to the glycolytic mode of carbon utilization is essential for rapid proliferative bursts, but its impact on self‐renewal is unclear. During the glycolytic mode of glucose utilization, glutamine‐derived carbons drive the mitochondrial TCA cycle. While glutamine is required for stem cell proliferation burst, its role in maintaining stem cell self‐renewal property remains unclear. Here, we show that withdrawal or chemical inhibition of mitochondrial glutamine metabolism blunted adult muscle stem cell proliferation, but also reactivated the transcription of self‐renewal‐associated transcripts, such as Pax7, to reduce stem cell heterogeneity and build the self‐renewing stem cell population. Thus, surprisingly, glutamine withdrawal preserved and accentuated the self‐renewing stem cell population. This effect of glutamine is mediated via reductive carboxylation of alpha‐ketoglutarate. Mechanistically, we extensively show that glutamine inhibited cell‐cycle linked self‐renewing network during the G2‐M phase of cell‐cycle to drive the exit from self‐renewal during the terminal mitosis phase before differentiation. Thus, we propose that glutamine metabolism plays an unexpected role in building the progenitor population that is uniquely primed for differentiation during tissue regeneration.

Auxilin regulates intestinal stem cell proliferation through EGFR.

SummaryAdult tissue homeostasis is maintained by residential stem cells. The proliferation and differentiation of adult stem cells must be tightly balanced to avoid excessive proliferation or premature differentiation. However, how stem cell proliferation is properly controlled remains elusive. Here, we find that auxilin (Aux) restricts intestinal stem cell (ISC) proliferation mainly through EGFR signaling. aux depletion leads to excessive ISC proliferation and midgut homeostasis disruption, which is unlikely caused by defective Notch signaling. Aux is expressed in multiple types of intestinal cells. Interestingly, aux depletion causes a dramatic increase in EGFR signaling, with a strong accumulation of EGFR at the plasma membrane and an increased expression of EGFR ligands in response to tissue stress. Furthermore, Aux co-localizes and associates with EGFR. Finally, blocking EGFR signaling completely suppresses the defects caused by aux depletion. Together, these data demonstrate that Aux mainly safeguards EGFR activation to keep a proper ISC proliferation rate to maintain midgut homeostasis.

Long-term iTBS promotes neural structural and functional recovery by enhancing neurogenesis and migration via miR-551b-5p/BDNF/TrkB pathway in a rat model of cerebral ischemia-reperfusion injury

As a novel form of repetitive transcranial stimulation, intermittent theta burst stimulation (iTBS) has potentials to be widely used in patients with stroke. Yet little is known about the idiographic actions of iTBS with different stimulation parameters on rehabilitative aspects of stroke patients, nor is the molecular mechanism underlying. In the present study, effects of iTBS with different stimulation parameters were evaluate to identify the optimal protocol of iTBS against damage induced by ischemia/reperfusion (I/R). Herein we found the short-term iTBS application seemed to have no significant effects on outcomes of rats during acute phase after I/R, including the neurological deficits, cerebral infarction and edema. However, behavioral functional tests demonstrated that long-term iTBS treatment provided effective therapy during subacute stage after two weeks post-stroke onset, which possibly by increasing proliferation and migration of adult neural stem cells. To explore the possible mechanisms of, microRNAs (miRs) expressional profiles were analyzed by microarray technology. Further bioinformatic analysis of binding sites revealed miR-551b-5p directly targeted the brain-derived neurotrophic factor (BDNF), which was confirmed by luciferase reporter and qRT-PCR. Moreover, the level phosphorylated-TrkB, the downstream of BDNF, was elevated accompanied by above-mentioned changes of long-term iTBS. Taken together, experimental data reveals a direct link between miR-551b-5p and BDNF-mediated signaling cascade in early convalescence of stroke. Our findings provide new insights into the molecular mechanisms underlying curative effects of iTBS on stroke, thus aiding in the prognosis and personalized therapies.

Toll-Like Receptor 5 Promotes the Neurogenesis From Embryonic Stem Cells and Adult Hippocampal Neural Stem Cells in Mice.

Toll-like receptors (TLRs) make a crucial contribution to the innate immune response. TLR5 was expressed in embryoid body derived from mouse embryonic stem cells (mESCs) and βIII-tubulin-positive cells under all-trans retinoic acid-treated condition. TLR5 was upregulated during neural differentiation from mESCs and augmented the neural differentiation of mESCs via nuclear factor-κB and interleukin 6/CREB pathways. Besides, TLR5 was expressed in SOX2- or doublecortin-positive cells in the subgranular zone of the hippocampal dentate gyrus where adult neurogenesis occurs. TLR5 inhibited the proliferation of adult hippocampal neural stem cells (NSCs) by regulating the cell cycle and facilitated the neural differentiation from the adult hippocampal NSCs via JNK pathway. Also, TLR5 deficiency impaired fear memory performance in mice. Our data suggest that TLR5 is a crucial modulator of neurogenesis from mESCs and adult hippocampal NSCs in mice and represents a new therapeutic target in neurological disorders related to cognitive function.

Three-dimensional printing of chitosan cryogel as injectable and shape recoverable scaffolds

Cryogel has macroporous structure and advantages of mechanical stability and injectability for biomedical applications. Three-dimensional (3D) printing is a customized manufacturing technology. However, there is little research on 3D printing of cryogel. In this work, we developed a 3D-printable chitosan cryogel using difunctional polyurethane nanoparticles as the crosslinker that reacted with chitosan at 4 °C for 4 h to form a stable feeding hydrogel (pre-cryogel) for 3D printing. The printed pre-cryogel was frozen at −20 °C to form 3D-printed chitosan cryogel. The 3D-printed cryogel had properties similar to those of bulk cryogel such as high compressibility, elastic recovery, and water absorption (≈3200%). Results from cell experiments indicated that the 3D-printed chitosan cryogel scaffolds provided good mechanical integrity for proliferation and chondrogenic differentiation of human adipose-derived adult stem cells. The 3D-printed chitosan cryogel scaffolds with injectability and shape recovery property are potential biomaterials for customized tissue engineering and minimally invasive surgery.

Sperm associated antigen 7 is activated by T3 during Xenopus tropicalis metamorphosis via a thyroid hormone response element within the first intron.

Thyroid hormone (T3) affects many diverse physiological processes such as metabolism, organogenesis, and growth. The two highly related frog species, diploid Xenopus tropicalis and pseudo tetraploid Xenopus laevis, have been used as models for analyzing the effects of T3 during vertebrate development. T3 regulates T3-inducible gene transcription through T3 receptor (TR)-binding to T3-response elements (TREs). We have previously identified sperm associated antigen 7 (spag7) as a candidate T3 target gene that is potentially involved in adult stem cell development and/or proliferation during intestinal metamorphosis. To investigate whether T3 regulates spag7 directly at the transcriptional level via TR, we first conducted qRT-PCR to analyze its expression during natural and T3-induced metamorphosis and found that spag7 was up-regulated during natural metamorphosis in the intestine, tail, brain and hindlimb, peaking at the climax of metamorphosis in all those organs, and upon T3 treatment of premetamorphic tadpoles. Next, we demonstrated that an intronic TRE in spag7, first identified through bioinformatic analysis, could bind to TR in vitro and in vivo during metamorphosis. A dual luciferase assay utilizing a reconstituted frog oocyte transcription system showed that the TRE could mediate promoter activation by liganded TR. These results indicate that spag7 expression is directly regulated by T3 through the TRE in the first intron during metamorphosis, implicating a role for spag7 early during T3-regulated tissue remodeling and resorption.