RESUMO
During development, neural progenitors undergo temporal patterning as they age to sequentially generate differently fated progeny. Temporal patterning of neural progenitors is relatively well-studied in Drosophila. Temporal cascades of transcription factors or opposing temporal gradients of RNA-binding proteins are expressed in neural progenitors as they age to control the fates of the progeny. The temporal progression is mostly driven by intrinsic mechanisms including cross-regulations between temporal genes, but environmental cues also play important roles in certain transitions. Vertebrate neural progenitors demonstrate greater plasticity in response to extrinsic cues. Recent studies suggest that vertebrate neural progenitors are also temporally patterned by a combination of transcriptional and post-transcriptional mechanisms in response to extracellular signaling to regulate neural fate specification. In this review, we summarize recent advances in the study of temporal patterning of neural progenitors in Drosophila and vertebrates. We also discuss the involvement of epigenetic mechanisms, specifically the Polycomb group complexes and ATP-dependent chromatin remodeling complexes, in the temporal patterning of neural progenitors.
Assuntos
Epigênese Genética , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Neurais/metabolismo , Neurogênese , Transdução de Sinais , Animais , Drosophila melanogasterRESUMO
Despite antiretroviral therapy (ART), people living with HIV (PLWH) are at increased risk of developing cardiovascular disease (CVD) and HIV-associated neurocognitive disorder (HAND), among other comorbidities. Studies from ART-treated individuals identified galectin-3 (gal-3) and interleukin (IL)-18 as CVD biomarkers, galectin-9 (gal-9) as a HAND biomarker, and sCD163, a marker of monocyte/macrophage activation, as a biomarker of both. We asked if plasma gal-3, gal-9, and IL-18 are associated with an individual comorbidity or increase in both with animals that develop AIDS with both pathologies versus (CVD-path) alone or simian immunodeficiency virus encephalitis (SIVE) alone. We found that no biomarkers were selective between individual pathologies, and all biomarkers increased with co-development of CVD-path and SIVE (gal-3, p = 0.11; gal-9, p = 0.001; IL-18, p = 0.007; sCD163, p < 0.001; %BrdU p = 0.02). Although gal-3, gal-9, and IL-18 did not distinguish between pathologies, they correlated strongly with one another, with sCD163, a marker of monocyte/macrophage activation, and the %BrdU monocytes, a marker of monocyte turnover. Compared to animals with CVD-path or SIVE alone, animals that co-developed both pathologies had consistently elevated IL-18 throughout infection (p = 0.02) and increased sCD163 in late infection (p = 0.01). These data indicate that gal-3, gal-9, and IL-18 are associated with monocyte/macrophage activation by sCD163 and monocyte turnover by the %BrdU+ monocytes more so than CVD-path or SIVE.
RESUMO
The salivary gland (SG) is an essential organ that secretes saliva, which supports versatile oral function throughout life, and is maintained by elusive epithelial stem and progenitor cells (SGSPC). Unfortunately, aging, drugs, autoimmune disorders, and cancer treatments can lead to salivary dysfunction and associated health consequences. Despite many ongoing therapeutic efforts to mediate those conditions, investigating human SGSPC is challenging due to lack of standardized tissue collection, limited tissue access, and inadequate purification methods. Herein, we established a diverse and clinically annotated salivary regenerative biobanking at the Mayo Clinic, optimizing viable salivary cell isolation and clonal assays in both 2D and 3D-matrigel growth environments. Our analysis identified ductal epithelial cells in vitro enriched with SGSPC expressing the CD24/EpCAM/CD49f+ and PSMA- phenotype. We identified PSMA expression as a reliable SGSPC differentiation marker. Moreover, we identified progenitor cell types with shared phenotypes exhibiting three distinct clonal patterns of salivary differentiation in a 2D environment. Leveraging innovative label-free unbiased LC-MS/MS-based single-cell proteomics, we identified 819 proteins across 71 single cell proteome datasets from purified progenitor-enriched parotid gland (PG) and sub-mandibular gland (SMG) cultures. We identified distinctive co-expression of proteins, such as KRT1/5/13/14/15/17/23/76 and 79, exclusively observed in rare, scattered salivary ductal basal cells, indicating the potential de novo source of SGSPC. We also identified an entire class of peroxiredoxin peroxidases, enriched in PG than SMG, and attendant H2O2-dependent cell proliferation in vitro suggesting a potential role for PRDX-dependent floodgate oxidative signaling in salivary homeostasis. The distinctive clinical resources and research insights presented here offer a foundation for exploring personalized regenerative medicine.
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How axon guidance pathways are utilized in coordination with temporal and spatial patterning of neural progenitors to regulate neuropil assembly is not well understood. We study this question in the Drosophila medulla using the transmedullary (Tm) projection neurons that target lobula through the inner optic chiasm (IOC). We demonstrate that the Netrin pathway plays multiple roles in guidance of Tm axons and that temporal patterning of medulla neuroblasts determines pioneer versus follower Tm neurons during this process. Loss of Frazzled (Fra) in early-born pioneer Tm neurons leads to IOC defects, while loss of Fra from follower neurons does not affect the IOC. In the follower projection neurons, Fra is required in other targeting steps including lobula branch extension and layer-specific targeting. Furthermore, different from other identified scenarios of Netrin/Fra involved axon guidance in Drosophila, we demonstrate that diffusible Netrin is required for the correct axon targeting and optic lobe organization.
Assuntos
Proteínas de Drosophila , Drosophila , Netrina-1 , Animais , Axônios/metabolismo , Drosophila/metabolismo , Proteínas de Drosophila/metabolismo , Receptores de Netrina/metabolismo , Netrina-1/genética , Netrina-1/metabolismo , Netrinas/genética , Netrinas/metabolismo , Neurônios/metabolismo , Receptores de Superfície Celular/metabolismoRESUMO
Notch-dependent binary fate choice between sister neurons is one of the mechanisms to generate neural diversity. How these upstream neural fate specification programs regulate downstream effector genes to control axon targeting and neuropil assembly remains less well understood. Here, we report that Notch-dependent binary fate choice in Drosophila medulla neurons is required to regulate the Netrin axon guidance pathway, which controls targeting of transmedullary (Tm) neurons to lobula. In medulla neurons of Notch-on hemilineage composed of mostly lobula-targeting neurons, Notch signaling is required to activate the expression of Netrin-B and repress the expression of its repulsive receptor Unc-5. Turning off Unc-5 is necessary for Tm neurons to target lobula. Furthermore, Netrin-B provided by Notch-on medulla neurons is required for correct targeting of Tm axons from later-generated medulla columns. Thus, the coordinate regulation of Netrin pathway components by Notch signaling ensures correct targeting of Tm axons and contributes to the neuropil assembly.
Assuntos
Orientação de Axônios , Drosophila , Animais , Axônios/metabolismo , Neurônios/metabolismo , Netrinas/metabolismo , Netrina-1/metabolismo , Receptores de Netrina/metabolismoRESUMO
BACKGROUND: Progressive Supranuclear Palsy (PSP) is an incurable neurodegenerative disorder. One variant of PSP is a frontal lobe cognitive or behavioral presentation (PSP-F). Currently, the primary management of this disease is rooted in neurological rehabilitation, therefore, early, and accurate diagnosis is key. CASE REPORT: Here we present a 60-year-old man with a 2-3-year history of functional decline and behavioral changes. He was misdiagnosed with a late-onset psychiatric disorder. During his second inpatient admission, a full workup for neurodegenerative diseases was performed, and the patient was ultimately diagnosed with probable PSP-F. We describe his neurological rehabilitation plan, examining recommendations before and after diagnosis. RESULTS: After the neurodegenerative disorder diagnosis, the neurological rehabilitation plan, particularly PT and OT, changed drastically despite no change in clinical presentation emphasizing the value of an appropriate and early diagnosis. Furthermore, in an OT session, the patient demonstrated longitudinal improvement, emphasizing the importance of rehabilitation in these patient's lives. CONCLUSION: Increased recognition of PSP variants amongst healthcare providers will allow more patients to receive early and appropriate diagnoses, so that they can benefit maximally from their neurological rehabilitation plans, maintain quality of life and experience longer periods of functioning. Furthermore, developing PSP-specific rehabilitation guidelines are crucial for improved outcomes. Correct diagnosis will also reduce the use of inappropriate and potentially harmful medications in these populations.
Assuntos
Doenças Neurodegenerativas , Paralisia Supranuclear Progressiva , Masculino , Humanos , Pessoa de Meia-Idade , Qualidade de Vida , Paralisia Supranuclear Progressiva/diagnósticoRESUMO
OBJECTIVE: Advancement of the endotracheal tube through a fibreoptic scope can sometimes prove to be challenging in obese patients. The Parker Flex-Tip endotracheal tube was developed with a curved and tapered distal tip to facilitate easier placement in the trachea. This study examined the use of the Parker Flex-Tip tube as compared to standard endotracheal tubes in patients with a body mass index of 30 or greater. METHODS: Sixty patients undergoing surgery requiring general anaesthesia were randomised into two groups. Using the fibreoptic scope, one group was intubated with the Parker Flex-Tip tube and the other group with a standard polyvinyl Portex tube. The time for intubation and the number of attempts required to place the endotracheal tube were measured and recorded. RESULTS: Using the Mann-Whitney U rank sum test, the median time needed for intubation with the two types of endotracheal tubes did not show a significant difference. The chi-square analyses were conducted for the number of attempts needed to place the endotracheal tubes, which also did not demonstrate any significant difference. CONCLUSIONS: Parker Flex-Tip endotracheal tube was not superior to the standard endotracheal tubes for fibreoptic intubation in obese patients.
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The human adenovirus type 5 early region 1A (E1A) is one of two oncogenes present in the adenovirus genome and functions by interfering with the activities of cellular regulatory proteins. The E1A gene is alternatively spliced to yield five products. Earlier studies have revealed that E1A can regulate the function of thyroid hormone (T3) receptors (TRs). However, analysis in yeast compared with transfection studies in mammalian cell cultures yields surprisingly different effects. Here, we have examined the effect of E1A on TR function by using the frog oocyte in vivo system, where the effects of E1A can be studied in the context of chromatin. We demonstrate that different isoforms of E1A have distinct effects on TR function. The two longest forms inhibit both the repression by unliganded TR and activation by T3-bound TR. We further show that E1A binds to unliganded TR to displace the endogenous corepressor nuclear receptor corepressor, thus relieving the repression by unliganded TR. On the other hand, in the presence of T3, E1A inhibits gene activation by T3-bound TR indirectly, through a mechanism that requires its binding domain for the general coactivator p300. Taken together, our results thus indicate that E1A affects TR function through distinct mechanisms that are dependent upon the presence or absence of T3.