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MicroPublication Biology 2023Immunofluorescence microscopy is a widely adopted method for studying meiotic prophase in the nematode model organism, . An in-depth examination of specific meiotic...
Immunofluorescence microscopy is a widely adopted method for studying meiotic prophase in the nematode model organism, . An in-depth examination of specific meiotic processes requires the quantitative analysis of immunofluorescence images, which often involves the segmentation of individual cells or nuclei. Here, we introduce our image analysis pipeline to automate significant portions of this task. This pipeline relies on the powerful deep learning model Cellpose 2.0 to segment cellular structures. To further improve the segmentation accuracy for germline nuclei stained for chromatin or synaptonemal complexes, we retrained the generalist Cellpose model and integrated our data processing pipeline into the easy-to-use Cell-ACDC image analysis software. Our pipeline thus makes deep learning-based segmentation of nuclei in the distal germline of accessible for users without coding experience.
PubMed: 38148986
DOI: 10.17912/micropub.biology.001062 -
Genes & Development Mar 2024H3K9 trimethylation (H3K9me3) plays emerging roles in gene regulation, beyond its accumulation on pericentric constitutive heterochromatin. It remains a mystery why and...
H3K9 trimethylation (H3K9me3) plays emerging roles in gene regulation, beyond its accumulation on pericentric constitutive heterochromatin. It remains a mystery why and how H3K9me3 undergoes dynamic regulation in male meiosis. Here, we identify a novel, critical regulator of H3K9 methylation and spermatogenic heterochromatin organization: the germline-specific protein ATF7IP2 (MCAF2). We show that in male meiosis, ATF7IP2 amasses on autosomal and X-pericentric heterochromatin, spreads through the entirety of the sex chromosomes, and accumulates on thousands of autosomal promoters and retrotransposon loci. On the sex chromosomes, which undergo meiotic sex chromosome inactivation (MSCI), the DNA damage response pathway recruits ATF7IP2 to X-pericentric heterochromatin, where it facilitates the recruitment of SETDB1, a histone methyltransferase that catalyzes H3K9me3. In the absence of ATF7IP2, male germ cells are arrested in meiotic prophase I. Analyses of ATF7IP2-deficient meiosis reveal the protein's essential roles in the maintenance of MSCI, suppression of retrotransposons, and global up-regulation of autosomal genes. We propose that ATF7IP2 is a downstream effector of the DDR pathway in meiosis that coordinates the organization of heterochromatin and gene regulation through the spatial regulation of SETDB1-mediated H3K9me3 deposition.
Topics: Germ Cells; Heterochromatin; Histones; Meiosis; Methylation; Male
PubMed: 38383062
DOI: 10.1101/gad.351569.124 -
Schizophrenia Research Jun 2024Although uncommon, the risk of aggression and violence is greater in people with schizophrenia than in the general population. Clozapine is the "gold standard"... (Review)
Review
Although uncommon, the risk of aggression and violence is greater in people with schizophrenia than in the general population. Clozapine is the "gold standard" pharmacologic treatment for the management of persistent agitation and aggression in people with schizophrenia and is consistently recommended by guidelines and reviews for this purpose. Although clozapine is indicated for treatment-resistant schizophrenia based on its superior efficacy, studies have proposed that clozapine may have specific properties that ameliorate aggression and hostility that are distinct from its antipsychotic effects. A literature review was conducted on June 3, 2023, using the US National Library of Medicine's PubMed resource to identify articles focusing on clozapine for the treatment of aggression, violence, and/or hostility in patients with schizophrenia or schizoaffective disorder. The majority of evidence, including from randomized control trials, supports the utilization of clozapine as maintenance treatment for persistent aggressive behavior in patients with schizophrenia, and supports that its anti-aggressive effects may be independent from its antipsychotic properties (e.g. - treatment of hallucinations and delusions). Future randomized control studies evaluating clozapine and clozapine serum levels with aggression as the primary outcome would be of benefit.
Topics: Humans; Clozapine; Aggression; Psychotic Disorders; Schizophrenia; Violence; Antipsychotic Agents
PubMed: 38290941
DOI: 10.1016/j.schres.2023.11.008 -
Journal of Cellular Physiology Jan 2024Meiosis is a specialized cell division that occurs in sexually reproducing organisms, generating haploid gametes containing half the chromosome number through two rounds... (Review)
Review
Meiosis is a specialized cell division that occurs in sexually reproducing organisms, generating haploid gametes containing half the chromosome number through two rounds of cell division. Homologous chromosomes pair and prepare for their proper segregation in subsequent divisions. How homologous chromosomes recognize each other and achieve pairing is an important question. Early studies showed that in most organisms, homologous pairing relies on homologous recombination. However, pairing mechanisms differ across species. Evidence indicates that chromosomes are dynamic and move during early meiotic stages, facilitating pairing. Recent studies in various model organisms suggest conserved mechanisms and key regulators of homologous chromosome pairing. This review summarizes these findings and compare similarities and differences in homologous chromosome pairing mechanisms across species.
Topics: Chromosome Pairing; Chromosome Segregation; Chromosomes; Homologous Recombination; Meiosis
PubMed: 38032002
DOI: 10.1002/jcp.31166 -
BioRxiv : the Preprint Server For... Jul 2023The centromere is an epigenetic mark that is a loading site for the kinetochore during meiosis and mitosis. This mark is characterized by the H3 variant CENP-A, known as...
The centromere is an epigenetic mark that is a loading site for the kinetochore during meiosis and mitosis. This mark is characterized by the H3 variant CENP-A, known as CID in . In , CENP-C is critical for maintaining CID at the centromeres and directly recruits outer kinetochore proteins after nuclear envelope break down. It is not known, however, if these two functions require the same CENP-C molecules. Furthermore, in and many other metazoan oocytes, centromere maintenance and kinetochore assembly are separated by an extended prophase. Consistent with studies in mammals, CID is relatively stable and does not need to be expressed during prophase to remain at high levels in metaphase I of meiosis. Expression of CID during prophase can even be deleterious, causing ectopic localization to non-centromeric chromatin, abnormal meiosis and sterility. In contrast to CID, maintaining high levels of CENP-C requires expression during prophase. Confirming the importance of this loading, we found CENP-C prophase loading is required for multiple meiotic functions. In early meiotic prophase, CENP-C loading is required for sister centromere cohesion and centromere clustering. In late meiotic prophase, CENP-C loading is required to recruit kinetochore proteins. CENP-C is one of the few proteins identified in which expression during prophase is required for meiotic chromosome segregation. An implication of these results is that the failure to maintain recruitment of CENP-C during the extended prophase in oocytes would result in chromosome segregation errors in oocytes.
PubMed: 36993339
DOI: 10.1101/2023.03.13.532437 -
The Journal of Cell Biology Feb 2024During meiosis, cohesin and meiosis-specific proteins organize chromatin into an axis-loop architecture, coordinating homologous synapsis, recombination, and ordered...
During meiosis, cohesin and meiosis-specific proteins organize chromatin into an axis-loop architecture, coordinating homologous synapsis, recombination, and ordered chromosome segregation. However, how the meiotic chromosome axis is assembled and differentiated with meiotic progression remains elusive. Here, we explore the dynamic recruitment of two long arms of the bivalent proteins, LAB-1 and LAB-2, in Caenorhabditis elegans. LAB proteins directly interact with the axis core HORMA complexes and weak interactions contribute to their recruitment. LAB proteins phase separate in vitro, and this capacity is promoted by HORMA complexes. During early prophase, synapsis oppositely regulates the axis enrichment of LAB proteins. After the pachytene exit, LAB proteins switch from a reciprocal localization pattern to a colocalization pattern, and the normal dynamic pattern of LAB proteins is altered in meiotic mutants. We propose that LAB recruitment senses axis differentiation, and phase separation of meiotic structures helps subdomain establishment and accurate segregation of the chromosomes.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cell Cycle Proteins; Chromosome Pairing; Chromosome Segregation; Chromosomes; Meiosis; Chromosomal Proteins, Non-Histone
PubMed: 38010234
DOI: 10.1083/jcb.202212035 -
Human Reproduction (Oxford, England) Nov 2023Are variants of genes involved in meiosis initiation responsible for premature ovarian insufficiency (POI)?
STUDY QUESTION
Are variants of genes involved in meiosis initiation responsible for premature ovarian insufficiency (POI)?
SUMMARY ANSWER
A MEIOSIN variant participates in the pathogenesis of human POI by impairing meiosis due to insufficient transcriptional activation of essential meiotic genes.
WHAT IS KNOWN ALREADY
Meiosis is the key event for the establishment of the ovarian reserve, and several gene defects impairing meiotic homologous recombination have been found to contribute to the pathogenesis of POI. Although STRA8 and MEIOISN variants have been found to associate with POI in a recent study, the condition of other meiosis initiation genes is unknown and direct evidence of variants participating in the pathogenesis of POI is still lacking.
STUDY DESIGN, SIZE, DURATION
This was a retrospective genetic study. An in-house whole exome sequencing (WES) database of 1030 idiopathic POI patients was screened for variations of meiosis initiation genes.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Homozygous or compound heterozygous variations of genes involved in meiosis initiation were screened in the in-house WES database. The pathogenicity of the variation was verified by in vitro experiments, including protein structure prediction and dual-luciferase reporter assay. The effect of the variant on ovarian function and meiosis was demonstrated through histological analyses in a point mutation mouse model.
MAIN RESULTS AND THE ROLE OF CHANCE
One homozygous variant in MEIOSIN (c.1735C>T, p.R579W) and one in STRA8 (c.258 + 1G>A), which initiates meiosis via the retinoic acid-dependent pathway, were identified in a patient with idiopathic POI respectively. The STRA8 variation has been reported in the recently published work. For the MEIOSIN variation, the dual-luciferase reporter assay revealed that the variant adversely affected the transcriptional function of MEIOSIN in upregulating meiotic genes. Furthermore, knock-in mice with the homologous mutation confirmed that the variation impacted the meiotic prophase I program and accelerated oocyte depletion. Moreover, the variant p.R579W localizing in the high-mobility group (HMG) box domain disrupted the nuclear localization of the MEIOSIN protein but was dispensable for the cell-cycle switch of oocytes, suggesting a unique role of the MEIOSIN HMG box domain in meiosis initiation.
LIMITATIONS, REASONS FOR CAUTION
Further studies are needed to explore the role of other meiosis initiation genes in the pathogenesis of POI.
WIDER IMPLICATIONS OF THE FINDINGS
The MEIOSIN variant was verified to cause POI by impaired transcriptional regulation of meiotic genes and was inherited by a recessive mode. The function of HMG box domain in MEIOSIN protein was also expanded by this study. Although causative variations in meiotic initiation genes are rare in POI, our study confirmed the pathogenicity of a MEIOSIN variant and elucidated another mechanism of human infertility.
STUDY FUNDING/COMPETING INTEREST(S)
This work was supported by the National Key Research & Developmental Program of China (2022YFC2703800, 2022YFC2703000), National Natural Science Foundation for Distinguished Young Scholars (82125014), National Natural Science Foundation of China (32070847, 32170867, 82071609), Basic Science Center Program of NSFC (31988101), Natural Science Foundation of Shandong Province for Grand Basic Projects (ZR2021ZD33), Natural Science Foundation of Shandong Province for Excellent Young Scholars (ZR2022YQ69), Taishan Scholars Program for Young Experts of Shandong Province (tsqn202211371), and Qilu Young Scholars Program of Shandong University. The authors declare no conflict of interest.
TRIAL REGISTRATION NUMBER
N/A.
Topics: Humans; Animals; Mice; Female; Meiosis; Retrospective Studies; Menopause, Premature; Primary Ovarian Insufficiency; Luciferases
PubMed: 37982418
DOI: 10.1093/humrep/dead084 -
The Lancet. Psychiatry Jul 2023
Topics: Humans; Schizophrenia; Antipsychotic Agents; Injections
PubMed: 37353255
DOI: 10.1016/S2215-0366(23)00069-X -
Revista Brasileira de Psiquiatria (Sao... 2023To determine the prevalence and correlates of treatment-resistant schizophrenia (TRS) through a systematic review and meta-analysis. (Meta-Analysis)
Meta-Analysis
OBJECTIVES
To determine the prevalence and correlates of treatment-resistant schizophrenia (TRS) through a systematic review and meta-analysis.
METHODS
Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria, an electronic search was performed in PubMed and Embase through May 17, 2022. All study designs that assessed a minimum of 20 schizophrenia-spectrum patients and provided data on TRS prevalence or allowed its calculation were included. Estimates were produced using a random-effects model meta-analysis.
RESULTS
The TRS prevalence across 50 studies (n = 29,390) was 36.7% (95%CI 33.1-40.5, p < 0.0001). The prevalence ranged from 22% (95%CI 18.4-25.8) in first-episode to 39.5% (95%CI 32.2-47.0) in multiple-episode samples (Q = 18.27, p < 0.0001). Primary treatment resistance, defined as no response from the first episode, was 23.6% (95%CI 20.5-26.8) vs. 9.3% (95%CI 6.8-12.2) for later-onset/secondary (≥ 6 months after initial treatment response). Longer illness duration and recruitment from long-term hospitals or clozapine clinics were associated with higher prevalence estimates. In meta-regression analyses, older age and poor functioning predicted greater TRS. When including only studies with lower bias risk, the TRS prevalence was 28.4%.
CONCLUSION
Different study designs and recruitment strategies accounted for most of the observed heterogeneity in TRS prevalence rates. The results point to early-onset and later-onset TRS as two separate disease pathways requiring clinical attention.
Topics: Humans; Antipsychotic Agents; Clozapine; Prevalence; Schizophrenia; Drug Resistance
PubMed: 37718484
DOI: 10.47626/1516-4446-2023-3126 -
Nucleic Acids Research Oct 2023Several aspects of telomere biology are regulated by the telomeric repeat-containing RNA TERRA. While TERRA expression is conserved through evolution, species-specific...
Several aspects of telomere biology are regulated by the telomeric repeat-containing RNA TERRA. While TERRA expression is conserved through evolution, species-specific mechanisms regulate its biogenesis and function. Here we report on the expression of TERRA in Caenorhabditis elegans. We show that C. elegans TERRA is regulated by the telomere-binding proteins POT-1 and POT-2 which repress TERRA in a telomere-specific manner. C. elegans TERRA transcripts are heterogeneous in length and form discrete nuclear foci, as detected by RNA FISH, in both postmitotic and germline cells; a fraction of TERRA foci localizes to telomeres. Interestingly, in germ cells, TERRA is expressed in all stages of meiotic prophase I, and it increases during pachytene, a stage in meiosis when homologous recombination is ongoing. We used the MS2-GFP system to study the spatiotemporal dynamics of single-telomere TERRA molecules. Single particle tracking revealed different types of motilities, suggesting complex dynamics of TERRA transcripts. Finally, we unveiled distinctive features of C. elegans TERRA, which is regulated by telomere shortening in a telomere-specific manner, and it is upregulated in the telomerase-deficient trt-1; pot-2 double mutant prior to activation of the alternative lengthening mechanism ALT. Interestingly, in these worms TERRA displays distinct dynamics with a higher fraction of fast-moving particles.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; DNA-Binding Proteins; Meiosis; RNA, Long Noncoding; Telomerase; Telomere; Telomere-Binding Proteins
PubMed: 37713629
DOI: 10.1093/nar/gkad742