In the 40 years since the discovery of the CENP proteins, many studies have examined the role of these proteins and their interactions with other chromosomal proteins of the centromere and beyond. Together, these studies have yielded vast amounts of sequencing and proteomics data. Typically, each study has focused on a single question and the majority of each dataset remains largely unexplored. Often the interesting details of publicly deposited data are left behind, buried in archives online, while more and more new data are generated. Reanalysing these databases can represent a new paradigm for investigating diverse biological pathways in unprecedented detail. Here, we explore two publicly available pan-cancer proteomic datasets to compare proteins whose abundance correlates with CENP proteins, with a particular focus on CENP-C. Our analysis confirms an expected link between CENP-C and cohesin levels but reveals a surprising and unexpected correlation between CENP-C and proteins of the inner nuclear membrane and the NuMA protein. This guilt-by-association analysis has the potential to identify proteins that act in common pathways but never associate or colocalize and may not even be expressed at the same time in cells. As an example, we show here that it can reveal unexpected links that expand our conception of centromeric chromatin beyond chromosome segregation.
Various long non-coding RNAs (lncRNAs) have indicated their role in different regulatory processes and therapeutics in cervical cancer (CC). This study aims to assess the gene expression and methylation status of LINC00518 MAFG-AS1 in CC patients. Methylation-specific PCR (MS-PCR) and quantitative real-time PCR (qRT-PCR) were performed on 81 patients. The association of the promoter methylation status of cancer tissues was studied with HPV infection and clinicopathological factors. The Kaplan-Meier curves were used from the GEPIA and TANRIC databases to analyze the overall survival of CC patients. The bioinformatics analysis of relative gene expression was carried out using the GEPIA database. The RNAinter database was also explored to find out the potential interacting partners. This is the first-ever research revealing that hypomethylation of the LINC00518 gene promoter may be relevant to its oncogenic behavior in CC (p < 0.05). However, no significant difference was observed between the MAFG-AS1 methylation status of cancerous and normal tissues. A notable association between the methylation status of LINC00518 promoter and clinicopathological factors, including age (p < 0.001), histological subtypes (p < 0.00001), and differentiation degree (p < 0.00001), has been observed, indicating its possible role in predicting the severity and prognosis of this disease. Overall survival analysis showed a significant value for LINC00518 using GEPIA (p < 0.05). Our findings about the gene expression of LINC00518 and its hypomethylated status in cancerous tissues suggest a potential mechanism that might contribute to its dysregulation in CC and could serve as a potential clinical biomarker.
In Drosophila melanogaster females, as in most organisms, the segregation of homologous chromosomes in meiosis depends on the formation of crossovers between them. In most cases, crossovers require the synaptonemal complex (SC), a conserved multi-protein structure that forms between homologous chromosomes in early meiosis. Recent studies leveraging partial-loss-of-function alleles suggest that the SC plays a more direct role in crossover formation. One SC protein that is involved in crossover formation is SYP-4 in nematodes, which we found is a likely ortholog of the D. melanogaster SC protein Corolla. To create a hypomorphic allele of corolla in D. melanogaster, we used CRISPR/Cas9 to replace it with its D. mauritiana ortholog, yielding corollamau. Since SC protein sequences are rapidly diverging while maintaining the SC’s structure, we hypothesized that this replacement would enable SC assembly but show defects in crossover formation. Indeed, at 25 °C corollamau homozygous females exhibited defects in SC maintenance and crossover formation, resulting in moderate levels of chromosome missegregation. At 18 °C, SC maintenance was rescued, and recombination rates were improved, although they remained significantly lower than observed in wild type. Unexpectedly, in homozygotes we also observed unique polycomplexes composed of the SC proteins Corolla and Corona but lacking the transverse filament protein C(3)G. Overall, we report a novel hypomorphic allele of corolla that suggests Corolla regulates crossover formation. Further, the unique polycomplexes found in mutant flies may provide new insights into SC architecture and protein-protein interactions.
The Heterochromatin Protein 1 (HP1) family proteins are key regulators of chromatin structure and genome function, acting as “reader” proteins that recognize and bind to histone H3 lysine 9 methylation (H3K9me). Beyond their canonical role in heterochromatin formation and transcriptional repression, HP1 proteins exhibit functional versatility, participating in transcriptional activation, RNA processing, DNA repair, and chromosome segregation. This multifunctionality is mediated partially by post-translational modifications (PTMs), with phosphorylation emerging as a central regulatory mechanism. This review explores the diverse effects of HP1 phosphorylation on protein function and chromatin interactions, focusing on Drosophila melanogaster HP1a and its orthologs, mammalian HP1α and S. pombe Swi6. Phosphorylation in the N-terminal tail enhances HP1’s affinity for H3K9me, promoting transcriptional silencing. Mitotic phosphorylation of serine residues in the hinge region, regulated by kinases such as AURKB and NDR1/2, leads to chromatin release and relocalization to the kinetochore, enabling proper chromosome segregation. Additionally, phosphorylation modulates HP1 phase separation dynamics, influencing nuclear compartmentalization and chromatin condensation. These findings highlight phosphorylation as a versatile molecular switch that enables HP1 proteins to transition between structural and regulatory roles, contributing to their evolutionary conserved multifunctionality in genome regulation and cell division. Further investigation into HP1 phosphorylation across species and contexts is essential to fully understand its contributions to chromatin biology.
