Multifaceted Roles of MeCP2 in Cellular Regulation and Phase Separation: Implications for Neurodevelopmental Disorders, Depression, and Oxidative Stress.

Methyl CpG binding protein 2 (MeCP2) is a chromatin-associated protein that remains enigmatic despite more than 30 years of research, primarily due to the ever-growing list of its molecular functions, and, consequently, its related pathologies. Loss of function MECP2 mutations cause the neurodevelopmental disorder Rett syndrome (RTT); in addition, dysregulation of MeCP2 expression and/or function are involved in numerous other pathologies, but the mechanisms of MeCP2 regulation are unclear. Advancing technologies and burgeoning mechanistic theories assist our understanding of the complexity of MeCP2 but may inadvertently cloud it if not rigorously tested.

The protamines of the spider Steatoda sp. provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis.

Although there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is, by comparison, very little information in Arthropoda. This study aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (order Araneae, family Theridiidae). To this end, we have developed a protein extraction method that allows the extraction of both cysteine-containing and non-cysteine-containing protamines that is suitable for the preparation and analysis of SNBPs from samples in which the amount of starting tissue material is limited.

Epigenetic modulation via the C-terminal tail of H2A.Z.

H2A.Z-nucleosomes are present in both euchromatin and heterochromatin and it has proven difficult to interpret their disparate roles in the context of their stability features. Using an in situ assay of nucleosome stability and DT40 cells expressing engineered forms of the histone variant we show that native H2A.

Testing the PEST hypothesis using relevant Rett mutations in MeCP2 E1 and E2 isoforms.

Mutations in methyl-CpG binding protein 2 (MeCP2), such as the T158M, P152R, R294X, and R306C mutations, are responsible for most Rett syndrome (RTT) cases. These mutations often result in altered protein expression that appears to correlate with changes in the nuclear size; however, the molecular details of these observations are poorly understood. Using a C2C12 cellular system expressing human MeCP2-E1 isoform as well as mouse models expressing these mutations, we show that T158M and P152R result in a decrease in MeCP2 protein, whereas R306C has a milder variation, and R294X resulted in an overall 2.

The protamines of the noble false widow spider provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis.

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is very little information about Arthropoda by comparison. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider (Order Araneae, Family Theridiidae). To this end, we have developed a protein extraction method that allows the extraction of cysteine-containing protamines suitable for the preparation and analysis of SNBPs from samples where the amount of starting tissue material is limited.

Chronic corticosterone exposure in rats induces sex-specific alterations in hypothalamic reelin fragments, MeCP2, and DNMT3a protein levels.

Women are disproportionately affected by stress-related disorders like depression. In our prior research, we discovered that females exhibit lower basal hypothalamic reelin levels, and these levels are differentially influenced by chronic stress induced through repeated corticosterone (CORT) injections. Although epigenetic mechanisms involving DNA methylation and the formation of repressor complexes by DNA methyl-transferases (DNMTs) and Methyl-CpG binding protein 2 (MeCP2) have been recognized as regulators of reelin expression in vitro, there is limited understanding of the impact of stress on the epigenetic regulation of reelin in vivo and whether sex differences exist in these mechanisms.

Protamines and the sperm nuclear basic proteins Pandora's Box of insects.

Insects are the largest group of animals when it comes to the number and diversity of species. Yet, with the exception of , no information is currently available on the primary structure of their sperm nuclear basic proteins (SNBPs). This paper represents the first attempt in this regard and provides information about six species of Neoptera: , and .

The sperm nuclear basic proteins of the sword fern ().

Sperm nuclear basic proteins (SNBPs) were isolated from extracted antheridia-rich male gametophytes raised from spores of the swordfern, . Electrophoretic (acetic acid-urea PAGE and SDS-PAGE) and chromatographic (rp-HPLC) characterization of the nuclear proteins exhibited the characteristics of the histone (H-type). In both types of gel electrophoresis, histones H1, H2A, and H2B showed an altered electrophoretic mobility corresponding to that which is routinely observed for the histones in other plants.

Extending MeCP2 interactome: canonical nucleosomal histones interact with MeCP2.

MeCP2 is a general regulator of transcription involved in the repression/activation of genes depending on the local epigenetic context. It acts as a chromatin regulator and binds with exquisite specificity to gene promoters. The set of epigenetic marks recognized by MeCP2 has been already established (mainly, cytosine modifications in CpG and CpA), as well as many of the constituents of its interactome.

Analysis of the interplay between MeCP2 and histone H1 during differentiation of human ReNCell neural progenitor cells.

An immortalized neural cell line derived from the human ventral mesencephalon, called ReNCell, and its MeCP2 knock out were used. With it, we characterized the chromatin compositional transitions undergone during differentiation, with special emphasis on linker histones. While the WT cells displayed the development of dendrites and axons the KO cells did not, despite undergoing differentiation as monitored by NeuN.

MeCP2 ubiquitination and sumoylation, in search of a function†.

MeCP2 (Methyl CpG binding protein 2) is an intrinsically disordered protein that binds to methylated genome regions. The protein is a critical transcriptional regulator of the brain, and its mutations account for 95% of Rett syndrome (RTT) cases. Early studies of this neurodevelopmental disorder revealed a close connection with dysregulations of the ubiquitin system (UbS), notably as related to UBE3A, a ubiquitin ligase involved in the proteasome-mediated degradation of proteins.

The Role of MeCP2 in Regulating Synaptic Plasticity in the Context of Stress and Depression.

Methyl-CpG-binding protein 2 (MeCP2) is a transcriptional regulator that is highly abundant in the brain. It binds to methylated genomic DNA to regulate a range of physiological functions implicated in neuronal development and adult synaptic plasticity. MeCP2 has mainly been studied for its role in neurodevelopmental disorders, but alterations in MeCP2 are also present in stress-related disorders such as major depression.

Spermiogenic chromatin condensation patterning in several hexapods may involve phase separation dynamics by spinodal decomposition or microemulsion inversion (nucleation).

We have examined published transmission electron microscopy (TEM). photomicrographs of chromatin condensation patterning in developing sperm nuclei from five species of entognathous hexapods within the Classes Protura, Collembola, Diplura and five species of ancestral wingless insects in the Orders Archaeognatha and Zygentoma as well as in fifteen species of the winged insects. Each species reproduces by internal fertilization.

MeCP2: The Genetic Driver of Rett Syndrome Epigenetics.

Mutations in methyl CpG binding protein 2 (MeCP2) are the major cause of Rett syndrome (RTT), a rare neurodevelopmental disorder with a notable period of developmental regression following apparently normal initial development. Such MeCP2 alterations often result in changes to DNA binding and chromatin clustering ability, and in the stability of this protein. Among other functions, MeCP2 binds to methylated genomic DNA, which represents an important epigenetic mark with broad physiological implications, including neuronal development.

MeCP2: latest insights fundamentally change our understanding of its interactions with chromatin and its functional attributes.

Methyl CpG binding protein 2 (MeCP2) was initially isolated as an exclusive reader of DNA methylated at CpG. This recognition site, was subsequently extended to other DNA methylated residues and it has been the persisting dogma that binding to methylated DNA constitutes its physiologically relevant role. As we review here, two very recent papers fundamentally change our understanding of the interactions of this protein with chromatin, as well as its functional attributes.

Deciphering the Enigma of the Histone H2A.Z-1/H2A.Z-2 Isoforms: Novel Insights and Remaining Questions.

The replication independent (RI) histone H2A.Z is one of the more extensively studied variant members of the core histone H2A family, which consists of many replication dependent (RD) members. The protein has been shown to be indispensable for survival, and involved in multiple roles from DNA damage to chromosome segregation, replication, and transcription.

Histone H4 variant, H4G, drives ribosomal RNA transcription and breast cancer cell proliferation by loosening nucleolar chromatin structure.

The hominidae-specific histone variant H4G is expressed in breast cancer patients in a stage-dependent manner. H4G localizes primarily in the nucleoli via its interaction with nucleophosmin (NPM1). H4G is involved in rDNA transcription and ribosome biogenesis, which facilitates breast cancer cell proliferation.

Doxorubicin induces large-scale and differential H2A and H2B redistribution in live cells.

We observed prominent effects of doxorubicin (Dox), an anthracycline widely used in anti-cancer therapy, on the aggregation and intracellular distribution of both partners of the H2A-H2B dimer, with marked differences between the two histones. Histone aggregation, assessed by Laser Scanning Cytometry via the retention of the aggregates in isolated nuclei, was observed in the case of H2A. The dominant effect of the anthracycline on H2B was its massive accumulation in the cytoplasm of the Jurkat leukemia cells concomitant with its disappearance from the nuclei, detected by confocal microscopy and mass spectrometry.

MeCP2-E1 isoform is a dynamically expressed, weakly DNA-bound protein with different protein and DNA interactions compared to MeCP2-E2.

Background: MeCP2-a chromatin-binding protein associated with Rett syndrome-has two main isoforms, MeCP2-E1 and MeCP2-E2, differing in a few N-terminal amino acid residues. Previous studies have shown brain region-specific expression of these isoforms which, in addition to their different cellular localization and differential expression during brain development, suggest that they may also have non-overlapping molecular mechanisms. However, differential functions of MeCP2-E1 and E2 remain largely unexplored.

EvoChromo: towards a synthesis of chromatin biology and evolution.

Over the past few years, interest in chromatin and its evolution has grown. To further advance these interests, we organized a workshop with the support of The Company of Biologists to debate the current state of knowledge regarding the origin and evolution of chromatin. This workshop led to prospective views on the development of a new field of research that we term 'EvoChromo'.