Literature context: uor 647 Invitrogen Cat# A21447; RRID:AB_141844 Rat monoclonal anti-FcÎ³III/II r
Intrinsic and evasive antiangiogenic drug (AAD) resistance is frequently developed in cancer patients, and molecular mechanisms underlying AAD resistance remain largely unknown. Here we describe AAD-triggered, lipid-dependent metabolic reprogramming as an alternative mechanism of AAD resistance. Unexpectedly, tumor angiogenesis in adipose and non-adipose environments is equally sensitive to AAD treatment. AAD-treated tumors in adipose environment show accelerated growth rates in the presence of a minimal number of microvessels. Mechanistically, AAD-induced tumor hypoxia initiates the fatty acid oxidation metabolic reprogramming and increases uptake of free fatty acid (FFA) that stimulates cancer cell proliferation. Inhibition of carnitine palmitoyl transferase 1A (CPT1) significantly compromises the FFA-induced cell proliferation. Genetic and pharmacological loss of CPT1 function sensitizes AAD therapeutic efficacy and enhances its anti-tumor effects. Together, we propose an effective cancer therapy concept by combining drugs that target angiogenesis and lipid metabolism.
Literature context: ; Invitrogen, Catalog #A-21447; RRID:AB_141844), or AlexaFluor 488-conjugated
Astrocyte-derived factors can control synapse formation and functions, making astrocytes an attractive target for regulating neuronal circuits and associated behaviors. Abnormal astrocyte-neuronal interactions are also implicated in neurodevelopmental disorders and neurodegenerative diseases associated with impaired learning and memory. However, little is known about astrocyte-mediated mechanisms that regulate learning and memory. Here, we propose astrocytic ephrin-B1 as a regulator of synaptogenesis in adult hippocampus and mouse learning behaviors. We found that astrocyte-specific ablation of ephrin-B1 in male mice triggers an increase in the density of immature dendritic spines and excitatory synaptic sites in the adult CA1 hippocampus. However, the prevalence of immature dendritic spines is associated with decreased evoked postsynaptic firing responses in CA1 pyramidal neurons, suggesting impaired maturation of these newly formed and potentially silent synapses or increased excitatory drive on the inhibitory neurons resulting in the overall decreased postsynaptic firing. Nevertheless, astrocyte-specific ephrin-B1 knock-out male mice exhibit normal acquisition of fear memory but enhanced contextual fear memory recall. In contrast, overexpression of astrocytic ephrin-B1 in the adult CA1 hippocampus leads to the loss of dendritic spines, reduced excitatory input, and impaired contextual memory retention. Our results suggest that astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and mediate excitatory synapse elimination through its interactions with neuronal EphB receptors. Indeed, a deletion of neuronal EphB receptors impairs the ability of astrocytes expressing functional ephrin-B1 to engulf synaptosomes in vitro Our findings demonstrate that astrocytic ephrin-B1 regulates long-term contextual memory by restricting new synapse formation in the adult hippocampus.SIGNIFICANCE STATEMENT These studies address a gap in our knowledge of astrocyte-mediated regulation of learning and memory by unveiling a new role for ephrin-B1 in astrocytes and elucidating new mechanisms by which astrocytes regulate learning. Our studies explore the mechanisms underlying astrocyte regulation of hippocampal circuit remodeling during learning using new genetic tools that target ephrin-B signaling in astrocytes in vivo On a subcellular level, astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and trigger astrocyte-mediated elimination of EphB receptor-containing synapses. Given the role EphB receptors play in neurodevelopmental disorders and neurodegenerative diseases, these findings establish a foundation for future studies of astrocyte-mediated synaptogenesis in clinically relevant conditions that can help to guide the development of clinical applications for a variety of neurological disorders.
Literature context: at IgG Invitrogen A21447 RRID:AB_141844 Alexa Fluoro 488 Donkey anti-ra
Cells demonstrate plasticity following injury, but the extent of this phenomenon and the cellular mechanisms involved remain underexplored. Using single-cell RNA sequencing (scRNA-seq) and lineage tracing, we uncover that myoepithelial cells (MECs) of the submucosal glands (SMGs) proliferate and migrate to repopulate the airway surface epithelium (SE) in multiple injury models. Specifically, SMG-derived cells display multipotency and contribute to basal and luminal cell types of the SMGs and SE. Ex vivo expanded MECs have the potential to repopulate and differentiate into SE cells when grafted onto denuded airway scaffolds. Significantly, we find that SMG-like cells appear on the SE of both extra- and intra-lobular airways of large animal lungs following severe injury. We find that the transcription factor SOX9 is necessary for MEC plasticity in airway regeneration. Because SMGs are abundant and present deep within airways, they may serve as a reserve cell source for enhancing human airway regeneration.
Literature context: ermo Fisher Scientific A-21447, RRID:AB_141844 Chemicals, Peptides, and Recomb
Genetic lineage tracing has revealed that Lgr5+ murine colon stem cells (CoSCs) rapidly proliferate at the crypt bottom. However, the spatiotemporal dynamics of human CoSCs in vivo have remained experimentally intractable. Here we established an orthotopic xenograft system for normal human colon organoids, enabling stable reconstruction of the human colon epithelium in vivo. Xenografted organoids were prone to displacement by the remaining murine crypts, and this could be overcome by complete removal of the mouse epithelium. Xenografted organoids formed crypt structures distinctively different from surrounding mouse crypts, reflecting their human origin. Lineage tracing using CRISPR-Cas9 to engineer an LGR5-CreER knockin allele demonstrated self-renewal and multipotency of LGR5+ CoSCs. In contrast to the rapidly cycling properties of mouse Lgr5+ CoSCs, human LGR5+ CoSCs were slow-cycling in vivo. This organoid-based orthotopic xenograft model enables investigation of the functional behaviors of human CoSCs in vivo, with potential therapeutic applications in regenerative medicine.
Literature context: :400 Molecular Probes A21447 RRID:AB_141844 647
Activation of Type III cells in mammalian taste buds is implicated in the transduction of acids (sour) and salty stimuli. Several lines of evidence suggest that function of Type III cells in the anterior taste fields may differ from that of Type III cells in posterior taste fields. Underlying anatomy to support this observation is, however, scant. Most existing immunohistochemical data characterizing this cell type focus on circumvallate taste buds in the posterior tongue. Equivalent data from anterior taste fields-fungiform papillae and soft palate-are lacking. Here, we compare Type III cells in four taste fields: fungiform, soft palate, circumvallate, and foliate in terms of reactivity to four canonical markers of Type III cells: polycystic kidney disease 2-like 1 (PKD2L1), synaptosomal associated protein 25 (SNAP25), serotonin (5-HT), and glutamate decarboxylase 67 (GAD67). Our findings indicate that while PKD2L1, 5-HT, and SNAP25 are highly coincident in posterior taste fields, they diverge in anterior taste fields. In particular, a subset of taste cells expresses PKD2L1 without the synaptic markers, and a subset of SNAP25 cells lacks expression of PKD2L1. In posterior taste fields, GAD67-positive cells are a subset of PKD2L1 expressing taste cells, but anterior taste fields also contain a significant population of GAD67-only expressing cells. These differences in expression patterns may underlie the observed functional differences between anterior and posterior taste fields.
Literature context: IgG Thermo Fisher Cat#:A21447; RRID:AB_141844 Goat Anti-Rabbit Immunoglobulin
As human pluripotent stem cells (hPSCs) exit pluripotency, they are thought to switch from a glycolytic mode of energy generation to one more dependent on oxidative phosphorylation. Here we show that, although metabolic switching occurs during early mesoderm and endoderm differentiation, high glycolytic flux is maintained and, in fact, essential during early ectoderm specification. The elevated glycolysis observed in hPSCs requires elevated MYC/MYCN activity. Metabolic switching during endodermal and mesodermal differentiation coincides with a reduction in MYC/MYCN and can be reversed by ectopically restoring MYC activity. During early ectodermal differentiation, sustained MYCN activity maintains the transcription of "switch" genes that are rate-limiting for metabolic activity and lineage commitment. Our work, therefore, shows that metabolic switching is lineage-specific and not a required step for exit of pluripotency in hPSCs and identifies MYC and MYCN as developmental regulators that couple metabolism to pluripotency and cell fate determination.
Literature context: ermo Fisher Scientific A-21447, RRID:AB_141844 AlexaFluor Donkey Anti-Rabbit 4
Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities, introducing inconsistencies that confound reproducibility and assessment of specific perturbations. Here we introduce a simple, modular protocol for deriving the four main ectodermal lineages from hPSCs. By precisely varying FGF, BMP, WNT, and TGFβ pathway activity in a minimal, chemically defined medium, we show parallel, robust, and reproducible derivation of neuroectoderm, neural crest (NC), cranial placode (CP), and non-neural ectoderm in multiple hPSC lines, on different substrates independently of cell density. We highlight the utility of this system by interrogating the role of TFAP2 transcription factors in ectodermal differentiation, revealing the importance of TFAP2A in NC and CP specification, and performing a small-molecule screen that identified compounds that further enhance CP differentiation. This platform provides a simple stage for systematic derivation of the entire range of ectodermal cell types.
Literature context: # A21447; RRID:AB_141844 were incub
Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT3 receptors on the gustatory nerves. We show here, using 5-HT3A GFP mice, that 5-HT3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus.
Literature context: A-21447; RRID:AB_141844 Alexa 488
Plasticity of adult neurogenesis supports adaptation to environmental changes. The identification of molecular mediators that signal these changes to neural progenitors in the niche has remained elusive. Here we report that diazepam binding inhibitor (DBI) is crucial in supporting an adaptive mechanism in response to changes in the environment. We provide evidence that DBI is expressed in stem cells in all neurogenic niches of the postnatal brain. Focusing on the hippocampal subgranular zone (SGZ) and employing multiple genetic manipulations in vivo, we demonstrate that DBI regulates the balance between preserving the stem cell pool and neurogenesis. Specifically, DBI dampens GABA activity in stem cells, thereby sustaining the proproliferative effect of physical exercise and enriched environment. Our data lend credence to the notion that the modulatory effect of DBI constitutes a general mechanism that regulates postnatal neurogenesis.
Literature context: #A-21447; RRID:AB_141844 Donkey ant
The accumulation of irreparable cellular damage restricts healthspan after acute stress or natural aging. Senescent cells are thought to impair tissue function, and their genetic clearance can delay features of aging. Identifying how senescent cells avoid apoptosis allows for the prospective design of anti-senescence compounds to address whether homeostasis can also be restored. Here, we identify FOXO4 as a pivot in senescent cell viability. We designed a FOXO4 peptide that perturbs the FOXO4 interaction with p53. In senescent cells, this selectively causes p53 nuclear exclusion and cell-intrinsic apoptosis. Under conditions where it was well tolerated in vivo, this FOXO4 peptide neutralized doxorubicin-induced chemotoxicity. Moreover, it restored fitness, fur density, and renal function in both fast aging XpdTTD/TTD and naturally aged mice. Thus, therapeutic targeting of senescent cells is feasible under conditions where loss of health has already occurred, and in doing so tissue homeostasis can effectively be restored.
Literature context: A-21447; RRID:AB_141844 Alexa Fluo
The suprachiasmatic nucleus (SCN) of the hypothalamus orchestrates daily rhythms of physiology and behavior in mammals. Its circadian (∼24 hr) oscillations of gene expression and electrical activity are generated intrinsically and can persist indefinitely in temporal isolation. This robust and resilient timekeeping is generally regarded as a product of the intrinsic connectivity of its neurons. Here we show that neurons constitute only one "half" of the SCN clock, the one metabolically active during circadian daytime. In contrast, SCN astrocytes are active during circadian nighttime, when they suppress the activity of SCN neurons by regulating extracellular glutamate levels. This glutamatergic gliotransmission is sensed by neurons of the dorsal SCN via specific pre-synaptic NMDA receptor assemblies containing NR2C subunits. Remarkably, somatic genetic re-programming of intracellular clocks in SCN astrocytes was capable of remodeling circadian behavioral rhythms in adult mice. Thus, SCN circuit-level timekeeping arises from interdependent and mutually supportive astrocytic-neuronal signaling.
Literature context: n A21447; RRID:AB_141844 Alexa Fluo
Loss of photoreceptors is a common endpoint in degenerative retinal diseases. Human pluripotent stem cells provide a potential source for photoreceptor replacement, but, even in mouse models, the efficiency and efficacy of transplantation-based repair remains poor. In this study, we examined the degree to which immune rejection contributes to these disappointing outcomes using an immunodeficient IL2 receptor γ (IL2rγ)-null mouse model. Our results show that prevention of cell rejection in the normal and degenerating retinal environment significantly improves long-term survival and integration of hESC-derived donor retinal cells. Transplanted cells are able to differentiate into mature photoreceptors expressing various opsins and can functionally integrate into congenitally blind mice. Our work suggests that even though the retina is often considered immune-privileged, suppression of host immune-mediated cell rejection may well be a useful approach for improving long-term integration of transplanted cells with a view to successful clinical outcomes.
Literature context: #A21447, RRID:AB_141844) for 2 d.
The brain is critically dependent on the regulation of blood flow to nourish active neurons. One widely held hypothesis of blood flow regulation holds that active neurons stimulate Ca(2+) increases in glial cells, triggering glial release of vasodilating agents. This hypothesis has been challenged, as arteriole dilation can occur in the absence of glial Ca(2+) signaling. We address this controversy by imaging glial Ca(2+) signaling and vessel dilation in the mouse retina. We find that sensory stimulation results in Ca(2+) increases in the glial endfeet contacting capillaries, but not arterioles, and that capillary dilations often follow spontaneous Ca(2+) signaling. In IP3R2(-/-) mice, where glial Ca(2+) signaling is reduced, light-evoked capillary, but not arteriole, dilation is abolished. The results show that, independent of arterioles, capillaries actively dilate and regulate blood flow. Furthermore, the results demonstrate that glial Ca(2+) signaling regulates capillary but not arteriole blood flow. SIGNIFICANCE STATEMENT: We show that a Ca(2+)-dependent glial cell signaling mechanism is responsible for regulating capillary but not arteriole diameter. This finding resolves a long-standing controversy regarding the role of glial cells in regulating blood flow, demonstrating that glial Ca(2+) signaling is both necessary and sufficient to dilate capillaries. While the relative contributions of capillaries and arterioles to blood flow regulation remain unclear, elucidating the mechanisms that regulate capillary blood flow may ultimately lead to the development of therapies for treating diseases where blood flow regulation is disrupted, including Alzheimer's disease, stroke, and diabetic retinopathy. This finding may also aid in revealing the underlying neuronal activity that generates BOLD fMRI signals.
Literature context: 7 (1:500; RRID:AB_141844, Invitroge
The medial septum (MS) is required for theta rhythmic oscillations and grid cell firing in the medial entorhinal cortex (MEC). While GABAergic, glutamatergic, and cholinergic neurons project from the MS to the MEC, their synaptic targets are unknown. To investigate whether MS neurons innervate specific layers and cell types in the MEC, we expressed channelrhodopsin-2 in mouse MS neurons and used patch-clamp recording in brain slices to determine the response to light activation of identified cells in the MEC. Following activation of MS axons, we observed fast monosynaptic GABAergic IPSPs in the majority (>60%) of fast-spiking (FS) and low-threshold-spiking (LTS) interneurons in all layers of the MEC, but in only 1.5% of nonstellate principal cells (NSPCs) and in no stellate cells. We also observed fast glutamatergic responses to MS activation in a minority (<5%) of NSPCs, FS, and LTS interneurons. During stimulation of MS inputs at theta frequency (10 Hz), the amplitude of GABAergic IPSPs was maintained, and spike output from LTS and FS interneurons was entrained at low (25-60 Hz) and high (60-180 Hz) gamma frequencies, respectively. By demonstrating cell type-specific targeting of the GABAergic projection from the MS to the MEC, our results support the idea that the MS controls theta frequency activity in the MEC through coordination of inhibitory circuits.