Thyroid hormone suppresses medulloblastoma progression through promoting terminal differentiation of tumor cells.

Hypothyroidism is commonly detected in patients with medulloblastoma (MB). However, whether thyroid hormone (TH) contributes to MB pathogenicity remains undetermined. Here, we find that TH plays a critical role in promoting tumor cell differentiation. Reduction in TH levels frees the TH receptor, TRα1, to bind to EZH2 and repress expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH reverses EZH2-mediated repression of NeuroD1 by abrogating the binding of EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, TH-induced differentiation of tumor cells is not restricted by the molecular subgroup of MB, suggesting that TH can be used to broadly treat MB subgroups. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising modality for MB treatment.

A Newly Developed Anti-L1CAM Monoclonal Antibody Targets Small Cell Lung Carcinoma Cells.

Few effective treatments are available for small cell lung cancer (SCLC), indicating the need to explore new therapeutic options. Here, we focus on an antibody-drug conjugate (ADC) targeting the L1 cell adhesion molecule (L1CAM). Several publicly available databases reveal that (1) L1CAM is expressed at higher levels in SCLC cell lines and tissues than in those of lung adenocarcinoma and (2) the expression levels of L1CAM are slightly higher in SCLC tissues than in adjacent normal tissues. We conducted a series of in vitro experiments using an anti-L1CAM monoclonal antibody (termed HSL175, developed in-house) and the recombinant protein DT3C, which consists of diphtheria toxin lacking the receptor-binding domain but containing the C1, C2, and C3 domains of streptococcal protein G. Our HSL175-DT3C conjugates theoretically kill cells only when the conjugates are internalized by the target (L1CAM-positive) cells through antigen-antibody interaction. The conjugates (an ADC analog) were effective against two SCLC-N (NEUROD1 dominant) cell lines, Lu-135 and STC-1, resulting in decreased viability. In addition, L1CAM silencing rendered the two cell lines resistant to HSL175-DT3C conjugates. These findings suggest that an ADC consisting of a humanized monoclonal antibody based on HSL175 and a potent anticancer drug would be effective against SCLC-N cells.

Efficient Dlx2-mediated astrocyte-to-neuron conversion and inhibition of neuroinflammation by NeuroD1.

In vivo astrocyte-to-neuron (AtN) conversion induced by overexpression of neural transcriptional factors has great potential for neural regeneration and repair. Here, we demonstrate that a single neural transcriptional factor, Dlx2, converts mouse striatal astrocytes into neurons in a dose-dependent manner. Lineage-tracing studies in Aldh1l1-CreERT2 mice confirm that Dlx2 can convert striatal astrocytes into DARPP32+ and Ctip2+ medium spiny neurons (MSNs). Time-course studies reveal a gradual conversion from astrocytes to neurons in 1 month, with a distinct intermediate state in between astrocytes and neurons. Interestingly, when Dlx2-infected astrocytes start to lose astrocytic markers, the other local astrocytes proliferate to maintain astrocytic levels in the converted areas. Unexpectedly, although Dlx2 efficiently reprograms astrocytes into neurons in the gray matter striatum, it also induces partial reprogramming of astrocytes in the white matter corpus callosum. Such partial reprogramming of white matter astrocytes is associated with neuroinflammation, which can be suppressed by the addition of NeuroD1. Our results highlight the importance of investigating AtN conversion in both the gray matter and white matter to thoroughly evaluate therapeutic potentials. This study also unveils the critical role of anti-inflammation by NeuroD1 during AtN conversion.

Controlling the Expression Level of the Neuronal Reprogramming Factors for a Successful Reprogramming Outcome.

Neuronal reprogramming is a promising approach for making major advancement in regenerative medicine. Distinct from the approach of induced pluripotent stem cells, neuronal reprogramming converts non-neuronal cells to neurons without going through a primitive stem cell stage. In vivo neuronal reprogramming brings this approach to a higher level by changing the cell fate of glial cells to neurons in neural tissue through overexpressing reprogramming factors. Despite the ongoing debate over the validation and interpretation of newly generated neurons, in vivo neuronal reprogramming is still a feasible approach and has the potential to become clinical treatment with further optimization and refinement. Here, we discuss the major neuronal reprogramming factors (mostly pro-neurogenic transcription factors during development), especially the significance of their expression levels during neurogenesis and the reprogramming process focusing on NeuroD1. In the developing central nervous system, these pro-neurogenic transcription factors usually elicit distinct spatiotemporal expression patterns that are critical to their function in generating mature neurons. We argue that these dynamic expression patterns may be similarly needed in the process of reprogramming adult cells into neurons and further into mature neurons with subtype identities. We also summarize the existing approaches and propose new ones that control gene expression levels for a successful reprogramming outcome.

Differential NEUROD1, ASCL1, and POU2F3 Expression Defines Molecular Subsets of Bladder Small Cell/Neuroendocrine Carcinoma With Prognostic Implications.

Small cell carcinomas (SMC) of the lung are now molecularly classified based on the expression of transcriptional regulators (NEUROD1, ASCL1, POU2F3, and YAP1) and DLL3, which has emerged as an investigational therapeutic target. PLCG2 has been shown to identify a distinct subpopulation of lung SMC with stem cell-like and prometastasis features and poor prognosis. We analyzed the expression of these novel neuroendocrine markers and their association with traditional neuroendocrine markers and patient outcomes in a cohort of bladder neuroendocrine carcinoma (NEC) consisting of 103 SMC and 19 large cell NEC (LCNEC) assembled in tissue microarrays. Coexpression patterns were assessed and integrated with detailed clinical annotation including overall (OS) and recurrence-free survival (RFS) and response to neoadjuvant/adjuvant chemotherapy. We identified 5 distinct molecular subtypes in bladder SMC based on the expression of ASCL1, NEUROD1, and POU2F3: ASCL1+/NEUROD1- (n = 33; 34%), ASCL1- /NEUROD1+ (n = 21; 21%), ASCL1+/NEUROD1+ (n = 17; 17%), POU2F3+ (n = 22, 22%), and ASCL1- /NEUROD1- /POU2F3- (n = 5, 5%). POU2F3+ tumors were mutually exclusive with those expressing ASCL1 and NEUROD1 and exhibited lower expression of traditional neuroendocrine markers. PLCG2 expression was noted in 33 tumors (32%) and was highly correlated with POU2F3 expression (P < .001). DLL3 expression was high in both SMC (n = 72, 82%) and LCNEC (n = 11, 85%). YAP1 expression was enriched in nonneuroendocrine components and negatively correlated with all neuroendocrine markers. In patients without metastatic disease who underwent radical cystectomy, PLCG2+ or POU2F3+ tumors had shorter RFS and OS (P < .05), but their expression was not associated with metastasis status or response to neoadjuvant/adjuvant chemotherapy. In conclusion, the NEC of the bladder can be divided into distinct molecular subtypes based on the expression of ASCL1, NEUROD1, and POU2F3. POU2F3-expressing tumors represent an ASCL1/NEUROD1-negative subset of bladder NEC characterized by lower expression of traditional neuroendocrine markers. Marker expression patterns were similar in SMC and LCNEC. Expression of PLCG2 and POU2F3 was associated with shorter RFS and OS. DLL3 was expressed at high levels in both SMC and LCNEC of the bladder, nominating it as a potential therapeutic target.

Olfactory neuroblastoma mimics molecular heterogeneity and lineage trajectories of small-cell lung cancer.

The olfactory epithelium undergoes neuronal regeneration from basal stem cells and is susceptible to olfactory neuroblastoma (ONB), a rare tumor of unclear origins. Employing alterations in Rb1/Trp53/Myc (RPM), we establish a genetically engineered mouse model of high-grade metastatic ONB exhibiting a NEUROD1+ immature neuronal phenotype. We demonstrate that globose basal cells (GBCs) are a permissive cell of origin for ONB and that ONBs exhibit cell fate heterogeneity that mimics normal GBC developmental trajectories. ASCL1 loss in RPM ONB leads to emergence of non-neuronal histopathologies, including a POU2F3+ microvillar-like state. Similar to small-cell lung cancer (SCLC), mouse and human ONBs exhibit mutually exclusive NEUROD1 and POU2F3-like states, an immune-cold tumor microenvironment, intratumoral cell fate heterogeneity comprising neuronal and non-neuronal lineages, and cell fate plasticity-evidenced by barcode-based lineage tracing and single-cell transcriptomics. Collectively, our findings highlight conserved similarities between ONB and neuroendocrine tumors with significant implications for ONB classification and treatment.

Molecular subtypes of neuroendocrine carcinomas: A cross-tissue classification framework based on five transcriptional regulators.

Neuroendocrine carcinomas (NECs) are extremely lethal malignancies that can arise at almost any anatomic site. Characterization of NECs is hindered by their rarity and significant inter- and intra-tissue heterogeneity. Herein, through an integrative analysis of over 1,000 NECs originating from 31 various tissues, we reveal their tissue-independent convergence and further unveil molecular divergence driven by distinct transcriptional regulators. Pan-tissue NECs are therefore categorized into five intrinsic subtypes defined by ASCL1, NEUROD1, HNF4A, POU2F3, and YAP1. A comprehensive portrait of these subtypes is depicted, highlighting subtype-specific transcriptional programs, genomic alterations, evolution trajectories, therapeutic vulnerabilities, and clinicopathological presentations. Notably, the newly discovered HNF4A-dominated subtype-H exhibits a gastrointestinal-like signature, wild-type RB1, unique neuroendocrine differentiation, poor chemotherapeutic response, and prevalent large-cell morphology. The proposal of uniform classification paradigm illuminates transcriptional basis of NEC heterogeneity and bridges the gap across different lineages and cytomorphological variants, in which context-dependent prevalence of subtypes underlies their phenotypic disparities.

Ectopic Expression of Neurod1 Is Sufficient for Functional Recovery following a Sensory-Motor Cortical Stroke.

Stroke is the leading cause of adult disability worldwide. The majority of stroke survivors are left with devastating functional impairments for which few treatment options exist. Recently, a number of studies have used ectopic expression of transcription factors that direct neuronal cell fate with the intention of converting astrocytes to neurons in various models of brain injury and disease. While there have been reports that question whether astrocyte-to-neuron conversion occurs in vivo, here, we have asked if ectopic expression of the transcription factor Neurod1 is sufficient to promote improved functional outcomes when delivered in the subacute phase following endothelin-1-induced sensory-motor cortex stroke. We used an adeno-associated virus to deliver Neurod1 from the short GFAP promoter and demonstrated improved functional outcomes as early as 28 days post-stroke and persisting to at least 63 days post-stroke. Using Cre-based cell fate tracking, we showed that functional recovery correlated with the expression of neuronal markers in transduced cells by 28 days post-stroke. By 63 days post-stroke, the reporter-expressing cells comprised ~20% of all the neurons in the perilesional cortex and expressed markers of cortical neuron subtypes. Overall, our findings indicate that ectopic expression of Neurod1 in the stroke-injured brain is sufficient to enhance neural repair.

Comprehensive analysis of transcription factor-based molecular subtypes and their correlation to clinical outcomes in small-cell lung cancer.

BACKGROUND: Recent studies have reported the predictive and prognostic value of novel transcriptional factor-based molecular subtypes in small-cell lung cancer (SCLC). We conducted an in-depth analysis pairing multi-omics data with immunohistochemistry (IHC) to elucidate the underlying characteristics associated with differences in clinical outcomes between subtypes. METHODS: IHC (n = 252), target exome sequencing (n = 422), and whole transcriptome sequencing (WTS, n = 189) data generated from 427 patients (86.4% males, 13.6% females) with SCLC were comprehensively analysed. The differences in the mutation profile, gene expression profile, and inflammed signatures were analysed according to the IHC-based molecular subtype. FINDINGS: IHC-based molecular subtyping, comprised of 90 limited-disease (35.7%) and 162 extensive-disease (64.3%), revealed a high incidence of ASCL1 subtype (IHC-A, 56.3%) followed by ASCL1/NEUROD1 co-expressed (IHC-AN, 17.9%), NEUROD1 (IHC-N, 12.3%), POU2F3 (IHC-P, 9.1%), triple-negative (IHC-TN, 4.4%) subtypes. IHC-based subtype showing high concordance with WTS-based subtyping and non-negative matrix factorization (NMF) clusterization method. IHC-AN subtype resembled IHC-A (rather than IHC-N) in terms of both gene expression profiles and clinical outcomes. Favourable median overall survival was observed in IHC-A (15.2 months) compared to IHC-N (8.0 months, adjusted HR 2.3, 95% CI 1.4-3.9, p = 0.002) and IHC-P (8.3 months, adjusted HR 1.7, 95% CI 0.9-3.2, p = 0.076). Inflamed tumours made up 25% of cases (including 53% of IHC-P, 26% of IHC-A, 17% of IHC-AN, but only 11% of IHC-N). Consistent with recent findings, inflamed tumours were more likely to benefit from first-line immunotherapy treatment than non-inflamed phenotype (p = 0.002). INTERPRETATION: This study provides fundamental data, including the incidence and basic demographics of molecular subtypes of SCLC using both IHC and WTS from a comparably large, real-world Asian/non-Western patient cohort, showing high concordance with the previous NMF-based SCLC model. In addition, we revealed underlying biological pathway activities, immunogenicity, and treatment outcomes based on molecular subtype, possibly related to the difference in clinical outcomes, including immunotherapy response. FUNDING: This work was supported by AstraZeneca, Future Medicine 2030 Project of the Samsung Medical Center [grant number SMX1240011], the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) [grant number 2020R1C1C1010626] and the 7th AstraZeneca-KHIDI (Korea Health Industry Development Institute) oncology research program.

Transcription Factors in Brain Regeneration: A Potential Novel Therapeutic Target.

Transcription factors play a crucial role in providing identity to each cell population. To maintain cell identity, it is essential to balance the expression of activator and inhibitor transcription factors. Cell plasticity and reprogramming offer great potential for future therapeutic applications, as they can regenerate damaged tissue. Specific niche factors can modify gene expression and differentiate or transdifferentiate the target cell to the required fate. Ongoing research is being carried out on the possibilities of transcription factors in regenerating neurons, with neural stem cells (NSCs) being considered the preferred cells for generating new neurons due to their epigenomic and transcriptome memory. NEUROD1/ASCL1, BRN2, MYTL1, and other transcription factors can induce direct reprogramming of somatic cells, such as fibroblasts, into neurons. However, the molecular biology of transcription factors in reprogramming and differentiation still needs to be fully understood.

NeuroD1 administration ameliorated neuroinflammation and boosted neurogenesis in a mouse model of subarachnoid hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) causes significant long-term neurocognitive dysfunction, which is associated with hippocampal neuroinflammation. Growing evidences have shown that astrocytes played a significant role in mediating neuroinflammation. Recently, in vivo reprogramming of astrocytes to neurons by NeuroD1 or PTBP1 administration has generated a lot of interests and controversies. While the debates centered on the source of neurogenesis, no attention has been paid to the changes of the astrocytes-mediated neuroinflammation and its impact on endogenous neurogenesis after NeuroD1 administration. METHODS: 80 adult male C57BL/6 mice were used in this study. SAH was established by pre-chiasmatic injection of 100 µl blood. AAV-NeuroD1-GFP virus was injected to the hippocampus 3 day post-SAH. Neurocognitive function, brain water content, in vivo electrophysiology, Golgi staining, western blot and immunofluorescent staining were assessed at day 14 post-virus injection. RESULTS: NeuroD1 administration markedly attenuated reactive astrocytes-mediated neuroinflammation by reversing neurotoxic A1 astrocytes transformation, decreasing the secretion of neuroinflammatory cytokines, and reducing the activation of harmful microglia. NeuroD1 treatment significantly reversed the brain-blood barrier impairment and promoted the release of neurotrophic factors pleiotrophin (PTN), all of which contributed to the improvement of cellular microenvironment and made it more suitable for neurogenesis. Interestingly, besides neurogenesis in the hippocampus from cells transfected with NeuroD1 at the early phase of SAH, NeuroD1 administration significantly boosted the endogenous neurogenesis at the late phase of SAH, which likely benefited from the improvement of the neuroinflammatory microenvironment. Functionally, NeuroD1 treatment significantly alleviated neurocognitive dysfunction impaired by SAH. CONCLUSIONS: NeuroD1 significantly promoted neurofunctional recovery by attenuating reactive astrocytes-mediated neuroinflammation and boosting neurogenesis decimated by SAH. Specifically, NeuroD1 efficiently converted transfected cells, most likely astrocytes, to neurons at the early phase of SAH, suppressed astrocytes-mediated neuroinflammation and boosted endogenous neurogenesis at the late phase of SAH.

Promoter-Specific Variants in NeuroD1 and H3K4me3 Coincident Regions and Clinical Outcomes of Small Cell Lung Cancer.

BACKGROUND: Neurogenic differentiation 1 (NeuroD1) is a representative small cell lung cancer (SCLC) transcription regulator involved in the carcinogenesis and behavior of SCLC. Histone modifications play an important role in transcription, and H3 lysine 4 trimethylation (H3K4me3) is primarily associated with promoter regions. METHODS: We investigated the association between single nucleotide polymorphisms (SNPs) in NeuroD1 and H3K4me3 coincident regions, selected using ChIP sequencing (ChIP-seq), and the clinical outcomes of 261 patients with SCLC. RESULTS: Among 230 SNPs, two were significantly associated with both the chemotherapy response and overall survival (OS) of patients with SCLC. RNF145 rs2043268A>G was associated with worse chemotherapy response and OS (under a recessive model, adjusted odds ratio [aOR], 0.50, 95% confidence interval [CI], 0.26-0.94, P = 0.031, and adjusted hazard ratio [aHR], 1.88, 95% CI, 1.38-2.57, P < 0.001). CINP rs762105A>G was also associated with worse chemotherapy response and OS (under a dominant model, aOR, 0.47, 95% CI, 0.23-0.99, P = 0.046, and aHR, 2.03, 95% CI, 1.47-2.82, P < 0.001). ChIP-quantitative polymerase chain reaction and luciferase assay confirmed that the two SNPs were located in the active promoter regions and influenced the promoter activity of each gene. CONCLUSION: To summarize, among SNPs selected using ChIP-seq in promoter regions with high peaks in both NeuroD1 and H3K4me3, RNF145 rs2043268A>G and CINP rs762105A>G were associated with clinical outcomes in patients with SCLC and also affected the promoter activity of each gene.

Direct neuronal conversion of microglia/macrophages reinstates neurological function after stroke.

Although generating new neurons in the ischemic injured brain would be an ideal approach to replenish the lost neurons for repairing the damage, the adult mammalian brain retains only limited neurogenic capability. Here, we show that direct conversion of microglia/macrophages into neurons in the brain has great potential as a therapeutic strategy for ischemic brain injury. After transient middle cerebral artery occlusion in adult mice, microglia/macrophages converge at the lesion core of the striatum, where neuronal loss is prominent. Targeted expression of a neurogenic transcription factor, NeuroD1, in microglia/macrophages in the injured striatum enables their conversion into induced neuronal cells that functionally integrate into the existing neuronal circuits. Furthermore, NeuroD1-mediated induced neuronal cell generation significantly improves neurological function in the mouse stroke model, and ablation of these cells abolishes the gained functional recovery. Our findings thus demonstrate that neuronal conversion contributes directly to functional recovery after stroke.

Overexpression of miR-124 in astrocyte improves neurological deficits in rat with ischemic stroke via DLL4 modulation.

BACKGROUND: Astrocytes have been demonstrated to undergo conversion into functional neurons, presenting a promising approach for stroke treatment. However, the development of small molecules capable of effectively inducing this cellular reprogramming remains a critical challenge. METHODS: Initially, we introduced a glial cell marker gene, GFaABC1D, as the promoter within an adeno-associated virus vector overexpressing miR-124 into the motor cortex of an ischemia-reperfusion model in rats. Additionally, we administered NeuroD1 as a positive control. Lentiviral vectors overexpressing miR-124 were constructed and transfected into primary rat astrocytes. We assessed the cellular distribution of GFAP, DCX, and NeuN on days 7, 14, and 28, respectively. RESULTS: In rats with ischemic stroke, miR-124-transduced glial cells exhibited positive staining for the immature neuron marker doublecortin (DCX) and the mature neuron marker NeuN after 4 weeks. In contrast, NeuroD1-overexpressing model rats only expressed NeuN, and the positive percentage was higher in co-transfection with miR-124 and NeuroD1. Overexpression of miR-124 effectively ameliorated neurological deficits and motor functional impairment in the model rats. In primary rat astrocytes transduced with miR-124, DCX was not observed after 7 days of transfection, but it appeared at 14 days, with the percentage further increasing to 44.6% at 28 days. Simultaneously, 15.1% of miR-124-transduced cells exhibited NeuN positivity, which was not detected at 7 and 14 days. In vitro, double fluorescence assays revealed that miR-124 targeted Dll4, and in vivo experiments confirmed that miR-124 inhibited the expression of Notch1 and DLL4. CONCLUSIONS: The overexpression of miR-124 in astrocytes demonstrates significant potential for improving neurological deficits following ischemic stroke by inhibiting DLL4 expression, and it may facilitate astrocyte-to-neuronal transformation.

Engineered neurogenesis in naïve adult rat cortex by Ngn2-mediated neuronal reprogramming of resident oligodendrocyte progenitor cells.

Adult tissue stem cells contribute to tissue homeostasis and repair but the long-lived neurons in the human adult cerebral cortex are not replaced, despite evidence for a limited regenerative response. However, the adult cortex contains a population of proliferating oligodendrocyte progenitor cells (OPCs). We examined the capacity of rat cortical OPCs to be re-specified to a neuronal lineage both in vitro and in vivo. Expressing the developmental transcription factor Neurogenin2 (Ngn2) in OPCs isolated from adult rat cortex resulted in their expression of early neuronal lineage markers and genes while downregulating expression of OPC markers and genes. Ngn2 induced progression through a neuronal lineage to express mature neuronal markers and functional activity as glutamatergic neurons. In vivo retroviral gene delivery of Ngn2 to naive adult rat cortex ensured restricted targeting to proliferating OPCs. Ngn2 expression in OPCs resulted in their lineage re-specification and transition through an immature neuronal morphology into mature pyramidal cortical neurons with spiny dendrites, axons, synaptic contacts, and subtype specification matching local cytoarchitecture. Lineage re-specification of rat cortical OPCs occurred without prior injury, demonstrating these glial progenitor cells need not be put into a reactive state to achieve lineage reprogramming. These results show it may be feasible to precisely engineer additional neurons directly in adult cerebral cortex for experimental study or potentially for therapeutic use to modify dysfunctional or damaged circuitry.

Exendin-4 ameliorates tau hyperphosphorylation and cognitive impairment in type 2 diabetes through acting on Wnt/ß-catenin/NeuroD1 pathway.

BACKGROUND: Type 2 diabetes (T2D) is an independent risk factor for Alzheimer's disease (AD). Exendin-4 (Ex-4), a widely used glucagon-like peptide-1 receptor agonist drug in the treatment of T2D, has been demonstrated the therapeutic effects on diabetic encephalopathy (DE). Especially, the Ex-4 ameliorates the tau hyperphosphorylation and cognitive impairment in DE. And these crucial alterations are also important bridge between T2D and AD. However, its unique mechanism is unclear. METHODS: The db/db mice, high-fat-diet (HFD) / streptozotocin (STZ)-induced diabetic (HF-diabetic) mice, and high-glucose-damaged (HGD) HT-22 hippocampal cells were enrolled to examine the effects of Ex-4 on AD-like changes in T2D. The Novel object recognition test (NORT) and Morris water maze test (MWMT) were conducted to evaluate the cognitive impairment. The Dickkopf-1 (DKK1) was employed to weaken the activation of the Wnt/ß-catenin pathway to explore the mechanism of Ex-4 in protecting the brain functions. The JASPAR was based to predict the interaction between NeuroD1 and the promoter region of Ins2. Moreover, the chromatin immunoprecipitation coupled with quantitative polymerase chain reaction (ChIP-qPCR) and luciferase reporter assays were performed. RESULTS: Ex-4 alleviated the tau hyperphosphorylation, increased the brain-derived insulin, and improved the PI3K/AKT/GSK3-ß signalling in db/db mice, HF-diabetic mice, and HGD HT-22 hippocampal neuronal cells. The NORT and MWMT indicated that Ex-4 alleviated the learning and memory deficits in HF-diabetic mice. The inhibitor Dickkopf-1 (DKK1) of the Wnt/ß-catenin pathway significantly blocked the protective effects of Ex-4. Regarding further molecular mechanisms, NeuroD1 was affected by Ex-4 in vivo and in vitro, and the knockdown or overexpression of NeuroD1 suggested its crucial role in promoting the brain insulin by Ex-4. Meanwhile, the ChIP‒qPCR and luciferase reporter assays confirmed the combination between NeuroD1 and the promoter region of the insulin-encoding gene Ins2. And this interaction could be promoted by Ex-4. CONCLUSIONS: Our study proposes that Ex-4 alleviates tau hyperphosphorylation and cognitive dysfunction by increasing Ins2-derived brain insulin through the Wnt/ß-catenin/NeuroD1 signaling in T2D. And its also show new lights on part of the progress and mechanism on treatment targets for the DE in T2D.

MicroRNA-375 Is Induced during Astrocyte-to-Neuron Reprogramming and Promotes Survival of Reprogrammed Neurons when Overexpressed.

While astrocyte-to-neuron (AtN) reprogramming holds great promise in regenerative medicine, the molecular mechanisms that govern this unique biological process remain elusive. To understand the function of miRNAs during the AtN reprogramming process, we performed RNA-seq of both mRNAs and miRNAs on human astrocyte (HA) cultures upon NeuroD1 overexpression. Bioinformatics analyses showed that NeuroD1 not only activated essential neuronal genes to initiate the reprogramming process but also induced miRNA changes in HA. Among the upregulated miRNAs, we identified miR-375 and its targets, neuronal ELAVL genes (nELAVLs), which encode a family of RNA-binding proteins and were also upregulated by NeuroD1. We further showed that manipulating the miR-375 level regulated nELAVLs' expression during NeuroD1-mediated reprogramming. Interestingly, miR-375/nELAVLs were also induced by the reprogramming factors Neurog2 and ASCL1 in HA, suggesting a conserved function to neuronal reprogramming, and by NeuroD1 in the mouse astrocyte culture and spinal cord. Functionally, we showed that miR-375 overexpression improved NeuroD1-mediated reprogramming efficiency by promoting cell survival at early stages in HA and did not appear to compromise the maturation of the reprogrammed neurons. Lastly, overexpression of miR-375-refractory ELAVL4 induced apoptosis and reversed the cell survival-promoting effect of miR-375 during AtN reprogramming. Together, we demonstrated a neuroprotective role of miR-375 during NeuroD1-mediated AtN reprogramming.

Concordance of ASCL1, NEUROD1 and POU2F3 transcription factor-based subtype assignment in paired tumour samples from small cell lung carcinoma.

AIMS: Small cell lung carcinoma (SCLC) can be classified into transcription factor-based subtypes (ASCL1, NeuroD1, POU2F3). While in-vitro studies suggest intratumoral heterogeneity in the expression of these markers, how SCLC subtypes vary over time and among locations in patients remains unclear. METHODS AND RESULTS: We searched a consecutive series of patients at our institution in 2006-22 for those with greater than one available formalin-fixed paraffin-embedded SCLC sample in multiple sites and/or time-points. Immunohistochemistry for ASCL1, NeuroD1 and POU2F3 was performed and evaluated using H-scores, with subtype assigned based on the positive marker (H-score threshold >10) with the highest H-score. The 179 samples (75, lung; 51, lymph nodes; 53, non-nodal metastases) from 84 patients (74 with two, 10 with more than two samples) included 98 (54.7%) ASCL1-dominant, 47 (26.3%) NeuroD1-dominant, 15 (8.4%) POU2F3-dominant, 17 (9.5%) triple-negative and two (1.1%) ASCL1/NeuroD1 co-dominant samples. NeuroD1-dominant subtype was enriched in non-lung locations. Subtype concordance from pairwise comparison was 71.4% overall and 89.7% after accounting for ASCL1/NeuroD1-dual expressors and technical factors including <500 cells/slide, H-score thresholds and sample decalcification. No significant difference in subtype concordance was noted with a longer time lapse or with extrathoracic versus intrathoracic samples in this cohort. CONCLUSIONS: After accounting for technical factors, transcription factor-based subtyping was discordant among multiple SCLC samples in ~10% of patients, regardless of sample locations and time lapse. Our findings highlighted the spatiotemporal heterogeneity of SCLC in clinical samples and potential challenges, including technical and biological factors, that might limit concordance in SCLC transcription factor-based subtyping.

Zebrafish pancreatic ß cell clusters undergo stepwise regeneration using Neurod1-expressing cells from different cell lineages.

Pancreatic ß cell clusters produce insulin and play a central role in glucose homeostasis. The regenerative capacity of mammalian ß cells is limited and the loss of ß cells causes diabetes. In contrast, zebrafish ß cell clusters have a high regenerative capacity, making them an attractive model to study ß cell cluster regeneration. How zebrafish ß cell clusters regenerate, when the regeneration process is complete, and the identification of the cellular source of regeneration are fundamental questions that require investigation. Here, using larval and adult zebrafish, we demonstrate that pancreatic ß cell clusters undergo a two-step regeneration process, regenerating functionality and then ß cell numbers. Additionally, we found that all regenerating pancreatic ß cells arose from Neurod1-expressing cells and that cells from different lineages contribute to both functional and ß cell number recovery throughout their life. Furthermore, we found that during development and neogenesis, as well as regeneration, all ß cells undergo Neurod1expression in zebrafish. Together, these results shed light on the fundamental cellular mechanisms underlying ß cell cluster development, neogenesis, and regeneration.

Identification of Lineage-specific Transcriptional Factor-defined Molecular Subtypes in Small Cell Bladder Cancer.

Small cell/neuroendocrine bladder cancers (SCBCs) are rare and highly aggressive tumors that are associated with poor clinical outcomes. We discovered that lineage-specific transcription factors (ASCL1, NEUROD1, and POU2F3) defined three SCBC molecular subtypes that resemble well-characterized subtypes in small cell lung cancer. The subtypes expressed various levels of neuroendocrine (NE) markers and distinct downstream transcriptional targets. Specifically, the ASCL1 and NEUROD1 subtypes had high NE marker expression and were enriched with different downstream regulators of the NE phenotype (FOXA2 and HES6, respectively). ASCL1 was also associated with the expression of delta-like ligands that control oncogenic Notch signaling. POU2F3, a master regulator of the NE low subtype, targeted TRPM5, SOX9, and CHAT. We also observed an inverse association between NE marker expression and immune signatures associated with sensitivity to immune checkpoint blockade, and the ASCL1 subtype had distinct targets for clinically available antibody-drug conjugates. These findings provide new insight into molecular heterogeneity in SCBCs with implications for the development of new treatment regimens. PATIENT SUMMARY: We investigated the levels of different proteins in a specific type of bladder cancer (small cell/neuroendocrine; SCBC). We could identify three distinct subtypes of SCBC with similarity to small cell/neuroendocrine cancers in other tissues. The results may help in identifying new treatment approaches for this type of bladder cancer.