Heterochromatin remodeling by CDK12 contributes to learning in Drosophila

Dynamic regulation of chromatin structure is required to modulate the transcription of genes in eukaryotes. However, the factors that contribute to the plasticity of heterochromatin structure are elusive. Here, we report that cyclin-dependent kinase 12 (CDK12), a transcription elongation-associated RNA polymerase II (RNAPII) kinase, antagonizes heterochromatin enrichment in Drosophila chromosomes. Notably, loss of CDK12 induces the ectopic accumulation of heterochromatin protein 1 (HP1) on euchromatic arms, with a prominent enrichment on the X chromosome. Furthermore, ChIP and sequencing analysis reveals that the heterochromatin enrichment on the X chromosome mainly occurs within long genes involved in neuronal functions. Consequently, heterochromatin enrichment reduces the transcription of neuronal genes in the adult brain and results in a defect in Drosophila courtship learning. Taken together, these results define a previously unidentified role of CDK12 in controlling the epigenetic transition between euchromatin and heterochromatin and suggest a chromatin regulatory mechanism in neuronal behaviors.

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Pericentromeric Heterochromatin Domains Are Maintained without Accumulation of HP1

Molecular Biology of the Cell ◽

10.1091/mbc.e06-01-0025 ◽

2007 ◽

Vol 18 (4) ◽

pp. 1464-1471 ◽

Cited By ~ 23

Author(s):

Julio Mateos-Langerak ◽

Maartje C. Brink ◽

Martijn S. Luijsterburg ◽

Ineke van der Kraan ◽

Roel van Driel ◽

...

Keyword(s):

Histone H3 ◽

Dominant Negative ◽

Pericentromeric Heterochromatin ◽

Heterochromatin Protein 1 ◽

Dapi Staining ◽

Heterochromatin Protein ◽

3T3 Fibroblasts ◽

Heterochromatin Structure ◽

Hp1 Proteins

The heterochromatin protein 1 (HP1) family is thought to be an important structural component of heterochromatin. HP1 proteins bind via their chromodomain to nucleosomes methylated at lysine 9 of histone H3 (H3K9me). To investigate the role of HP1 in maintaining heterochromatin structure, we used a dominant negative approach by expressing truncated HP1α or HP1β proteins lacking a functional chromodomain. Expression of these truncated HP1 proteins individually or in combination resulted in a strong reduction of the accumulation of HP1α, HP1β, and HP1γ in pericentromeric heterochromatin domains in mouse 3T3 fibroblasts. The expression levels of HP1 did not change. The apparent displacement of HP1α, HP1β, and HP1γ from pericentromeric heterochromatin did not result in visible changes in the structure of pericentromeric heterochromatin domains, as visualized by DAPI staining and immunofluorescent labeling of H3K9me. Our results show that the accumulation of HP1α, HP1β, and HP1γ at pericentromeric heterochromatin domains is not required to maintain DAPI-stained pericentromeric heterochromatin domains and the methylated state of histone H3 at lysine 9 in such heterochromatin domains.

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Regulation of Morphological and Functional Aspects of Sexual Dimorphism in the Brain

10.5772/intechopen.97470 ◽

2021 ◽

Author(s):

Chitose Orikasa

Keyword(s):

Sexual Dimorphism ◽

Sex Steroids ◽

Perinatal Period ◽

Adult Brain ◽

Functional Aspects ◽

Neuronal Functions ◽

And Control ◽

The Brain ◽

Neuroendocrine Functions

Sexual dimorphism of the adult brain regulates sex-dependent functions including reproductive and neuroendocrine activities in rodents. It is determined by sex steroid hormones during a critical perinatal period in female and male rodents. Sex steroids act on each nuclear receptor in the brain and control different physiological and neuroendocrine functions and behaviors. Several regions of the brain show evident morphological sex differences that are involved in their physiological functions. This review addresses and focuses largely on the role of sex-dependent differences in the brain, and their crucial functions in animal models. Particularly, recent intriguing data concerning the diversity of neuronal functions and sexual dimorphism are discussed.

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Recent advances in dynamic m 6 A RNA modification

Open Biology ◽

10.1098/rsob.160003 ◽

2016 ◽

Vol 6 (4) ◽

pp. 160003 ◽

Cited By ~ 95

Author(s):

Guangchao Cao ◽

Hua-Bing Li ◽

Zhinan Yin ◽

Richard A. Flavell

Keyword(s):

Rna Splicing ◽

High Throughput Sequencing ◽

Epigenetic Modification ◽

Rna Modification ◽

Sequencing Analysis ◽

Biological Functions ◽

Dynamic Regulation ◽

The Past ◽

Recent Advances

The identification of m 6 A demethylases and high-throughput sequencing analysis of methylated transcriptome corroborated m 6 A RNA epigenetic modification as a dynamic regulation process, and reignited its investigation in the past few years. Many basic concepts of cytogenetics have been revolutionized by the growing understanding of the fundamental role of m 6 A in RNA splicing, degradation and translation. In this review, we summarize typical features of methylated transcriptome in mammals, and highlight the ‘writers’, ‘erasers’ and ‘readers’ of m 6 A RNA modification. Moreover, we emphasize recent advances of biological functions of m 6 A and conceive the possible roles of m 6 A in the regulation of immune response and related diseases.

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Role of melatonin in regulating neurogenesis: Implications for the neurodegenerative pathology and analogous therapeutics for Alzheimer’s disease

Melatonin Research ◽

10.32794/mr11250059 ◽

2020 ◽

Vol 3 (2) ◽

pp. 216-242 ◽

Cited By ~ 1

Author(s):

Mayuri Shukla ◽

Areechun Sotthibundhu ◽

Piyarat Govitrapong

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Adult Neurogenesis ◽

Adult Brain ◽

Therapeutic Approaches ◽

Therapeutic Implications ◽

Cell Proliferation And Differentiation ◽

Proliferation And Differentiation ◽

Progenitor Cell Proliferation

The revelation of adult brain exhibiting neurogenesis has established that the brain possesses great plasticity and that neurons could be spawned in the neurogenic zones where hippocampal adult neurogenesis attributes to learning and memory processes. With strong implications in brain functional homeostasis, aging and cognition, various aspects of adult neurogenesis reveal exuberant mechanistic associations thereby further aiding in facilitating the therapeutic approaches regarding the development of neurodegenerative processes in Alzheimer’s Disease (AD). Impaired neurogenesis has been significantly evident in AD with compromised hippocampal function and cognitive deficits. Melatonin the pineal indolamine augments neurogenesis and has been linked to AD development as its levels are compromised with disease progression. Here, in this review, we discuss and appraise the mechanisms via which melatonin regulates neurogenesis in pathophysiological conditions which would unravel the molecular basis in such conditions and its role in endogenous brain repair. Also, its components as key regulators of neural stem and progenitor cell proliferation and differentiation in the embryonic and adult brain would aid in accentuating the therapeutic implications of this indoleamine in line of prevention and treatment of AD.

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Bisection of the X chromosome disrupts the initiation of chromosome silencing during meiosis in Caenorhabditis elegans

Nature Communications ◽

10.1038/s41467-021-24815-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yisrael Rappaport ◽

Hanna Achache ◽

Roni Falk ◽

Omer Murik ◽

Oren Ram ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Rna Polymerase Ii ◽

X Chromosome ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Transcription Analysis ◽

X Chromosomes ◽

Unique Character ◽

Active Transcription ◽

Heterogametic Sex

AbstractDuring meiosis, gene expression is silenced in aberrantly unsynapsed chromatin and in heterogametic sex chromosomes. Initiation of sex chromosome silencing is disrupted in meiocytes with sex chromosome-autosome translocations. To determine whether this is due to aberrant synapsis or loss of continuity of sex chromosomes, we engineered Caenorhabditis elegans nematodes with non-translocated, bisected X chromosomes. In early meiocytes of mutant males and hermaphrodites, X segments are enriched with euchromatin assembly markers and active RNA polymerase II staining, indicating active transcription. Analysis of RNA-seq data showed that genes from the X chromosome are upregulated in gonads of mutant worms. Contrary to previous models, which predicted that any unsynapsed chromatin is silenced during meiosis, our data indicate that unsynapsed X segments are transcribed. Therefore, our results suggest that sex chromosome chromatin has a unique character that facilitates its meiotic expression when its continuity is lost, regardless of whether or not it is synapsed.

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Early Consumption of Cannabinoids: From Adult Neurogenesis to Behavior

International Journal of Molecular Sciences ◽

10.3390/ijms22147450 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7450

Author(s):

Citlalli Netzahualcoyotzi ◽

Luis Miguel Rodríguez-Serrano ◽

María Elena Chávez-Hernández ◽

Mario Humberto Buenrostro-Jáuregui

Keyword(s):

Young Adulthood ◽

Adult Neurogenesis ◽

Critical Period ◽

Consumption Rate ◽

Behavioral Outcomes ◽

Endocannabinoid System ◽

Illegal Drug ◽

Adult Brain ◽

As Stress

The endocannabinoid system (ECS) is a crucial modulatory system in which interest has been increasing, particularly regarding the regulation of behavior and neuroplasticity. The adolescent–young adulthood phase of development comprises a critical period in the maturation of the nervous system and the ECS. Neurogenesis occurs in discrete regions of the adult brain, and this process is linked to the modulation of some behaviors. Since marijuana (cannabis) is the most consumed illegal drug globally and the highest consumption rate is observed during adolescence, it is of particular importance to understand the effects of ECS modulation in these early stages of adulthood. Thus, in this article, we sought to summarize recent evidence demonstrating the role of the ECS and exogenous cannabinoid consumption in the adolescent–young adulthood period; elucidate the effects of exogenous cannabinoid consumption on adult neurogenesis; and describe some essential and adaptive behaviors, such as stress, anxiety, learning, and memory. The data summarized in this work highlight the relevance of maintaining balance in the endocannabinoid modulatory system in the early and adult stages of life. Any ECS disturbance may induce significant modifications in the genesis of new neurons and may consequently modify behavioral outcomes.

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AIF3 splicing switch triggers neurodegeneration

Molecular Neurodegeneration ◽

10.1186/s13024-021-00442-7 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Shuiqiao Liu ◽

Mi Zhou ◽

Zhi Ruan ◽

Yanan Wang ◽

Calvin Chang ◽

...

Keyword(s):

Cell Death ◽

Neurodegenerative Diseases ◽

Mitochondrial Dysfunction ◽

Nuclear Translocation ◽

Chromatin Condensation ◽

Neuronal Cell ◽

Adult Brain ◽

Postmortem Brain ◽

Mitochondrial Functions

Abstract Background Apoptosis-inducing factor (AIF), as a mitochondrial flavoprotein, plays a fundamental role in mitochondrial bioenergetics that is critical for cell survival and also mediates caspase-independent cell death once it is released from mitochondria and translocated to the nucleus under ischemic stroke or neurodegenerative diseases. Although alternative splicing regulation of AIF has been implicated, it remains unknown which AIF splicing isoform will be induced under pathological conditions and how it impacts mitochondrial functions and neurodegeneration in adult brain. Methods AIF splicing induction in brain was determined by multiple approaches including 5′ RACE, Sanger sequencing, splicing-specific PCR assay and bottom-up proteomic analysis. The role of AIF splicing in mitochondria and neurodegeneration was determined by its biochemical properties, cell death analysis, morphological and functional alterations and animal behavior. Three animal models, including loss-of-function harlequin model, gain-of-function AIF3 knockin model and conditional inducible AIF splicing model established using either Cre-loxp recombination or CRISPR/Cas9 techniques, were applied to explore underlying mechanisms of AIF splicing-induced neurodegeneration. Results We identified a nature splicing AIF isoform lacking exons 2 and 3 named as AIF3. AIF3 was undetectable under physiological conditions but its expression was increased in mouse and human postmortem brain after stroke. AIF3 splicing in mouse brain caused enlarged ventricles and severe neurodegeneration in the forebrain regions. These AIF3 splicing mice died 2–4 months after birth. AIF3 splicing-triggered neurodegeneration involves both mitochondrial dysfunction and AIF3 nuclear translocation. We showed that AIF3 inhibited NADH oxidase activity, ATP production, oxygen consumption, and mitochondrial biogenesis. In addition, expression of AIF3 significantly increased chromatin condensation and nuclear shrinkage leading to neuronal cell death. However, loss-of-AIF alone in harlequin or gain-of-AIF3 alone in AIF3 knockin mice did not cause robust neurodegeneration as that observed in AIF3 splicing mice. Conclusions We identified AIF3 as a disease-inducible isoform and established AIF3 splicing mouse model. The molecular mechanism underlying AIF3 splicing-induced neurodegeneration involves mitochondrial dysfunction and AIF3 nuclear translocation resulting from the synergistic effect of loss-of-AIF and gain-of-AIF3. Our study provides a valuable tool to understand the role of AIF3 splicing in brain and a potential therapeutic target to prevent/delay the progress of neurodegenerative diseases.

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Loss of Non-Apoptotic Role of Caspase-3 in the PINK1 Mouse Model of Parkinson’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms20143407 ◽

2019 ◽

Vol 20 (14) ◽

pp. 3407 ◽

Cited By ~ 2

Author(s):

Paola Imbriani ◽

Annalisa Tassone ◽

Maria Meringolo ◽

Giulia Ponterio ◽

Graziella Madeo ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Synaptic Plasticity ◽

Mouse Model ◽

Caspase 3 ◽

Cysteine Proteases ◽

Synaptic Function ◽

Adult Brain ◽

Striatal Slices

Caspases are a family of conserved cysteine proteases that play key roles in multiple cellular processes, including programmed cell death and inflammation. Recent evidence shows that caspases are also involved in crucial non-apoptotic functions, such as dendrite development, axon pruning, and synaptic plasticity mechanisms underlying learning and memory processes. The activated form of caspase-3, which is known to trigger widespread damage and degeneration, can also modulate synaptic function in the adult brain. Thus, in the present study, we tested the hypothesis that caspase-3 modulates synaptic plasticity at corticostriatal synapses in the phosphatase and tensin homolog (PTEN) induced kinase 1 (PINK1) mouse model of Parkinson’s disease (PD). Loss of PINK1 has been previously associated with an impairment of corticostriatal long-term depression (LTD), rescued by amphetamine-induced dopamine release. Here, we show that caspase-3 activity, measured after LTD induction, is significantly decreased in the PINK1 knockout model compared with wild-type mice. Accordingly, pretreatment of striatal slices with the caspase-3 activator α-(Trichloromethyl)-4-pyridineethanol (PETCM) rescues a physiological LTD in PINK1 knockout mice. Furthermore, the inhibition of caspase-3 prevents the amphetamine-induced rescue of LTD in the same model. Our data support a hormesis-based double role of caspase-3; when massively activated, it induces apoptosis, while at lower level of activation, it modulates physiological phenomena, like the expression of corticostriatal LTD. Exploring the non-apoptotic activation of caspase-3 may contribute to clarify the mechanisms involved in synaptic failure in PD, as well as in view of new potential pharmacological targets.

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