A novel NF2 splicing mutant causes neurofibromatosis type 2 via liquid-liquid phase separation with large tumor suppressor and Hippo pathway

High de novo mutation rate in Iranian NF2-related schwannomatosis patients with a report of a novel NF2 mutation

BACKGROUND

NF2-related schwannomatosis (NF2) is a rare genetic disease that significantly impacts patients' quality of life due to the occurrence of multiple tumors within the nervous system. The high clinical heterogeneity in tumor number, location, and size makes predicting each patient's clinical outcome impossible. Genetic investigation can be crucial in diagnosis, prognosis, and management. This study aims to explore the genetic basis of eight Iranian patients with NF2.

METHODS AND RESULTS

To investigate potential genetic causes, we conducted comprehensive medical evaluations, whole-exome sequencing (WES), and multiplex ligation-dependent probe amplification (MLPA) on the probands of each family. The identified variants in the family members were confirmed using Sanger sequencing and MLPA. The variants were classified according to the American College of Medical Genetics and Genomics guidelines. Seven distinct variants linked to the NF2 gene were identified as causes of NF2-related schwannomatosis in these patients, among which the c.862_863del frameshift was a novel variant not previously reported. Seventy-five percent of these mutations were de novo. The mean diagnostic age was lower among patients with truncating mutations compared to other patients.

CONCLUSIONS

This study identified a novel mutation in the NF2 gene and showed a high rate of de novo mutations in Iranian NF2 patients. Moreover, patients with truncating mutations experienced earlier symptoms than others. Comparing the manifestations of each patient with similar mutations to previous reports expands our understanding of the phenotype of NF2. These results can provide more comprehensive insights into prognosis and early interventions.

Emerging regulatory mechanisms and functions of biomolecular condensates: implications for therapeutic targets

Cells orchestrate their processes through complex interactions, precisely organizing biomolecules in space and time. Recent discoveries have highlighted the crucial role of biomolecular condensates-membrane-less assemblies formed through the condensation of proteins, nucleic acids, and other molecules-in driving efficient and dynamic cellular processes. These condensates are integral to various physiological functions, such as gene expression and intracellular signal transduction, enabling rapid and finely tuned cellular responses. Their ability to regulate cellular signaling pathways is particularly significant, as it requires a careful balance between flexibility and precision. Disruption of this balance can lead to pathological conditions, including neurodegenerative diseases, cancer, and viral infections. Consequently, biomolecular condensates have emerged as promising therapeutic targets, with the potential to offer novel approaches to disease treatment. In this review, we present the recent insights into the regulatory mechanisms by which biomolecular condensates influence intracellular signaling pathways, their roles in health and disease, and potential strategies for modulating condensate dynamics as a therapeutic approach. Understanding these emerging principles may provide valuable directions for developing effective treatments targeting the aberrant behavior of biomolecular condensates in various diseases.

NF2 can mediate the expression of CAMK2A in a tissue specific manner

Meningioma is the most prevalent primary intracranial tumor, with approximately half of patients harboring NF2 alteration. The rationale behind the presence of NF2 alteration in meningiomas and its absence in non-nerve system tumors remains elusive. Therefore, meningiomas and several non-nerve system tumor types were analyzed using KEGG analysis and CRISPR/Cas 9 technology to determine the role of NF2 in regulating tissue specificity. Moreover, the different regulatory patterns of Ca2+ and calcium/calmodulin-dependent protein kinase II alpha (CAMK2A) that play a decisive role in NF2 tissue-specific regulation were deciphered. Our results revealed that NF2 has a positive correlation in CAMK2A expression in both meningiomas and normal nervous system tissues but not in non-nervous system tumors and tissues, implying NF2 tissue-specificity is mediated by CAMK2A-related pathways. Thus, targeting CAMK2A may represent a promising strategy for drug screening and the development of therapeutics for NF2-associated meningiomas and other nervous system tumors.

The role of liquid-liquid phase separation in defining cancer EMT

Cancer EMT is a pivotal process that drives carcinogenesis, metastasis, and cancer recurrence, with its initiation and regulation intricately governed by biochemical pathways in a precise spatiotemporal manner. Recently, the membrane-less biomolecular condensates formed via liquid-liquid phase separation (LLPS) have emerged as a universal mechanism underlying the spatiotemporal collaboration of biological activities in cancer EMT. In this review, we first elucidate the current understanding of LLPS formation and its cellular functions, followed by an overview of valuable tools for investigating LLPS. Secondly, we examine in detail the LLPS-mediated biological processes crucial for the initiation and regulation of cancer EMT. Lastly, we address current challenges in advancing LLPS research and explore the potential modulation of LLPS using therapeutic agents.

NF2 regulates IP3R-mediated Ca2+ signal and apoptosis in meningiomas

Meningiomas are the most common primary intracranial tumors and account for nearly 30% of all nervous system tumors. Approximately half of meningioma patients exhibit neurofibromin 2 (NF2) gene inactivation. Here, NF2 was shown to interact with the endoplasmic reticulum (ER) calcium (Ca2+) channel inositol 1,4,5-trisphosphate receptor 1 (IP3R1) in IOMM-Lee, a high-grade malignant meningioma cell line, and the F1 subdomain of NF2 plays a critical role in this interaction. Functional assays indicated that NF2 promotes the phosphorylation of IP3R (Ser 1756) and IP3R-mediated endoplasmic reticulum (ER) Ca2+ release by binding to IP3R1, which results in Ca2+-dependent apoptosis. Knockout of NF2 decreased Ca2+ release and promoted resistance to apoptosis, which was rescued by wild-type NF2 overexpression but not by F1 subdomain deletion truncation overexpression. The effects of NF2 defects on the development of tumors were further studied in mouse models. The decreased expression level of NF2 caused by NF2 gene knockout or mutation affects the activity of the IP3R channel, which reduces Ca2+-dependent apoptosis, thereby promoting the development of tumors. We elucidated the interaction patterns of NF2 and IP3R1, revealed the molecular mechanism through which NF2 regulates IP3R1-mediated Ca2+ release, and elucidated the new pathogenic mechanism of meningioma-related NF2 variants. Our study broadens the current understanding of the biological function of NF2 and provides ideas for drug screening of NF2-associated meningioma.

New Insights into YAP/TAZ-TEAD-Mediated Gene Regulation and Biological Processes in Cancer

The Hippo pathway is conserved across species. Key mammalian Hippo pathway kinases, including MST1/2 and LATS1/2, inhibit cellular growth by inactivating the TEAD coactivators, YAP, and TAZ. Extensive research has illuminated the roles of Hippo signaling in cancer, development, and regeneration. Notably, dysregulation of Hippo pathway components not only contributes to tumor growth and metastasis, but also renders tumors resistant to therapies. This review delves into recent research on YAP/TAZ-TEAD-mediated gene regulation and biological processes in cancer. We focus on several key areas: newly identified molecular patterns of YAP/TAZ activation, emerging mechanisms that contribute to metastasis and cancer therapy resistance, unexpected roles in tumor suppression, and advances in therapeutic strategies targeting this pathway. Moreover, we provide an updated view of YAP/TAZ's biological functions, discuss ongoing controversies, and offer perspectives on specific debated topics in this rapidly evolving field.