Project description:Generating diverse neurons involves spatially distinct neural stem cells that show age dependent developmental fates. Drosophila neuroblasts produce long, diverse yet stereotyped series of distinct neurons, called lineages. We searched for novel temporal factors that could pattern such extended lineages by RNA-sequencing of specific neuroblasts at various developmental times. We found that two RNA-binding proteins, Imp and Syp, display opposing high-to-low and low-to-high temporal gradients with distinct dynamics in specific lineages. Manipulating Imp/Syp levels in mushroom body neuroblasts revealed opposing roles in the specification of early and late temporal fates, primarily via regulation of Chinmo translation. This study implicates the opposing Imp/Syp gradients as temporal morphogens that encode stem cell age and govern birth time-dependent offspring cell fate through post-transcriptional regulation of temporal dentity genes.
Project description:One neural stem cell can produce multiple transiently amplifying, intermediate neural progenitors (INP), which collectively yield diverse neuronal types. It is unclear if and how serially derived INPs contribute to neuron fate diversification. Drosophila type II neuroblasts, like mammalian neural stem cells, deposit neurons and also glia through INPs. The consecutively born INPs in a given lineage produce morphologically distinct progeny, presumably due to their inheritance of different temporal factors from the INP-producing progenitor. To uncover the underlying temporal fating mechanisms, we profiled type II neuroblasts' transcriptome across time. Our results reveal opposing temporal gradients of Imp and Syp RNA-binding proteins (descending and ascending, respectively). Maintaining high Imp throughout serial INP production expands the number of neurons/glia with early temporal fate at the expense of cells with late fate. Conversely, precocious upregulation of Syp reduces the number of cells with early fate. Further, we reveal that the transcription factor, Seven-up initiates progression of the Imp/Syp gradients. Interestingly, neuroblasts apparently locked in their beginning Imp/Syp levels can still yield progeny with a small range of early fates. We propose that the Seven-up-initiated Imp/Syp gradients create coarse temporal windows within type II neuroblasts to pattern INPs, which subsequently undergo fine-tuned subtemporal patterning.
Project description:Neuron specification and maturation are essential for proper central nervous system development. However, the precise mechanisms that govern neuronal maturation, essential to shape and maintain neuronal circuitry, remain poorly understood. Here, we analyse early-born secondary neurons in the Drosophila larval brain revealing that the early maturation of secondary neurons goes through three consecutive phases: 1) Immediately after birth, neurons express pan-neuronal markers but do not transcribe terminal differentiation genes; 2) Transcription of terminal differentiation genes, such as neurotransmitter-related genes VGlut, ChAT or Gad1, starts shortly after neuron birth, but these transcripts are however not translated; 3) Translation of neurotransmitter-related genes only begins several hours later in mid pupa stages in a coordinated manner with animal developmental stage, albeit in an ecdysone independent-manner. These results support a model where temporal regulation of transcription and translation of neurotransmitter-related genes is an important mechanism to coordinate neuron maturation with brain development.
Project description:The neuroendocrine (NE) phenotype is associated with the development of metastatic castration-resistant prostate cancer (CRPC). Our objective was to characterize the molecular features of the NE phenotype in CRPC. Expression of chromogranin A (CHGA), synaptophysin (SYP), androgen receptor (AR), and prostate-specific antigen (PSA) was analyzed by immunohistochemistry (IHC) in 155 CRPC metastases from 50 patients and in 24 LuCaP prostate cancer patient-derived xenografts (PDX). Co-expression of CHGA and SYP in >30% of cells was observed in 22 of 155 metastases (9 patients); 11 of the 22 metastases were AR+/PSA+ (6 patients), 11/22 were AR-/PSA- (4 patients), and 4/24 LuCaP PDXs were AR-/PSA-. Seventy-one of 155 metastases and the 24 LuCaP xenograft lines were analyzed by whole genome microarrays. By IHC, of the 71 metastases analyzed by whole genome microarrays, 5 metastases were CHGA+/SYP+/AR- and 5 were CHGA+/SYP+/AR+. Only CHGA+/SYP+ metastases had a NE transcript signature. The neuronal transcriptional regulator SRRM4 transcript was associated with the NE signature in CHGA+/SYP+ metastases and all CHGA+/SYP+ LuCaP xenografts. Additionally, expression of SRRM4 in the LuCaP NE xenografts correlated with a splice variant of REST that lacks the transcriptional repressor domain. In conclusion, (a) metastatic NE status can be heterogeneous in the same patient, (b) the CRPC NE molecular phenotype can be defined by CHGA+/SYP+ dual positivity, (c) the NE phenotype is not necessarily associated with the loss of AR activity, and (d) the splicing of REST by SRRM4 could promote the NE phenotype in CRPC. Custom Agilent 44K whole human genome expression oligonucleotide microarrays were used to profile 24 LuCaP PCa xenograft lines and 71 CRPC metastases from 47 patients. RNA was amplified prior to hybridization against a common reference pool of prostate tumor cell lines.
Project description:Pediatric neural tumors are initiated during embryonic/fetal stages and rapidly become malignant despite carrying few genetic alterations. However, the molecular basis of this early malignant susceptibility remains unknown. During Drosophila development, malignant neural tumors can arise from single gene inactivation triggering dedifferentiation towards a neural stem cell (NSC)-like state. Here, we find that these tumors originate from a sub-population of early-born neural progeny that transiently co-express the mRNA-binding proteins Lin-28 and Imp/IGF2BP, and the transcription factor Chinmo. These three genes compose an early growth module that is co-opted in a subset of dedifferentiated cells to propagate unlimited proliferation. In late NSCs, Chinmo, Imp and Lin-28 are silenced by temporal transcription factors for timely termination of neurogenesis. Consequently, late-born progeny do not express the module and become refractory to malignant transformation. Thus, this study identifies the NSC-intrinsic developmental program that predisposes neural progeny to malignant transformation according to their birth order.
Project description:The neuroendocrine (NE) phenotype is associated with the development of metastatic castration-resistant prostate cancer (CRPC). Our objective was to characterize the molecular features of the NE phenotype in CRPC. Expression of chromogranin A (CHGA), synaptophysin (SYP), androgen receptor (AR), and prostate-specific antigen (PSA) was analyzed by immunohistochemistry (IHC) in 155 CRPC metastases from 50 patients and in 24 LuCaP prostate cancer patient-derived xenografts (PDX). Co-expression of CHGA and SYP in >30% of cells was observed in 22 of 155 metastases (9 patients); 11 of the 22 metastases were AR+/PSA+ (6 patients), 11/22 were AR-/PSA- (4 patients), and 4/24 LuCaP PDXs were AR-/PSA-. Seventy-one of 155 metastases and the 24 LuCaP xenograft lines were analyzed by whole genome microarrays. By IHC, of the 71 metastases analyzed by whole genome microarrays, 5 metastases were CHGA+/SYP+/AR- and 5 were CHGA+/SYP+/AR+. Only CHGA+/SYP+ metastases had a NE transcript signature. The neuronal transcriptional regulator SRRM4 transcript was associated with the NE signature in CHGA+/SYP+ metastases and all CHGA+/SYP+ LuCaP xenografts. Additionally, expression of SRRM4 in the LuCaP NE xenografts correlated with a splice variant of REST that lacks the transcriptional repressor domain. In conclusion, (a) metastatic NE status can be heterogeneous in the same patient, (b) the CRPC NE molecular phenotype can be defined by CHGA+/SYP+ dual positivity, (c) the NE phenotype is not necessarily associated with the loss of AR activity, and (d) the splicing of REST by SRRM4 could promote the NE phenotype in CRPC.
Project description:How to respond to starvation determines fitness. One prominent behavioral response is increased locomotor activities upon starvation, also known as Starvation-Induced Hyperactivity (SIH). SIH is paradoxical as it promotes food seeking but also increases energy expenditure. Despite its importance in regulating fitness, the genetic contributions to SIH as a behavioral trait remains unexplored. Here, we examined SIH in the Drosophila melanogaster Genetic Reference Panel (DGRP) and performed genome-wide association studies. We identified 27 significant loci, corresponding to 18 genes, significantly associated with SIH in adult Drosophila. Gene enrichment analyses indicated that genes encoding ion channels and mRNA binding proteins (RBPs) were most enriched in SIH. We are especially interested in RBPs because they provide a potential mechanism to quickly change protein expression in response to environmental challenges. Using RNA interference, we validated the role of Syp in regulating SIH. Syp encodes Syncrip, an RBP. While ubiquitous knockdown of Syp led to lethality during development, adult flies with neuron specific Syp knockdown were viable and exhibited decreased SIH. Using the Temporal and Regional Gene Expression Targeting (TARGET) system, we further confirmed the role of Syp in adult neurons in regulating SIH. Lastly, RNA-seq analyses revealed that Syp was alternatively spliced under starvation while its expression level was unchanged. Together, this study not only demonstrates genetic contributions to SIH as an important behavioral trait but also highlights the significance of RBPs and post-transcriptional processes in regulating SIH.
Project description:To identify dysfunctional neuronal subtypes underlying seizure activity in the human brain, we have performed single-nucleus transcriptomics analysis of >110,000 neuronal transcriptomes derived from temporal cortex samples of multiple temporal lobe epilepsy and non-epileptic subjects.
Project description:As a newly-invented and highly-efficiency strobilurin fungicide, pyraoxystrobin (SYP-3343) has been recognized as a highly poisonous toxin for a variety of aquatic organisms. Nevertheless, the developmental toxicity and potential mechanism of SYP-3343 have not been well-documented. The results showed that SYP-3343 was relatively stable and maintained within the range of 20 % in 24 h, and the LC50 value to embryos at 72 hpf was 17.13 μg/L. The zebrafish embryotoxicity induced by 1, 2, 4, and 8 μg/L SYP-3343 is demonstrated by repressive embryo incubation, enhancive mortality rate, abnormal heart rate, malformed morphological characteristic, and impaired spontaneous coiling, indicating SYP-3343 mostly exerted its toxicity in a dose- and time-dependent manner. Besides SYP-3343 was critically involved in regulating cell cycle, mitochondrial membrane potential, and reactive oxygen species production as well as zebrafish primary cells apoptosis, which can be mitigated using antioxidant N-acetyl-L-cysteine. A significant change occurred in total protein content, the biochemical indices, and antioxidant capacities owing to SYP-3343 exposure. Additionally, SYP-3343 altered the mRNA levels of heart development-, mitochondrial function-, and apoptosis-related genes in zebrafish embryos. These results indicated that SYP-3343 induced apoptosis accompanying reactive oxygen species-initiated mitochondrial dysfunction in zebrafish embryos.