Profiling NSD3-dependent neural crest gene expression reveals known and novel candidate regulatory factors

NSD3 in Cancer: Unraveling Methyltransferase-Dependent and Isoform-Specific Functions

NSD3 (nuclear receptor-binding SET domain protein 3) is a member of the NSD histone methyltransferase family of proteins. In recent years, it has been identified as a potential oncogene in certain types of cancer. The NSD3 gene encodes three isoforms, the long version (NSD3L), a short version (NSD3S) and the WHISTLE isoforms. Importantly, the NSD3S isoform corresponds to the N-terminal region of the full-length protein, lacking the methyltransferase domain. The chromosomal location of NSD3 is frequently amplified across cancer types, such as breast, lung, and colon, among others. Recently, this amplification has been correlated to a chromothripsis event, that could explain the different NSD3 alterations found in cancer. The fusion proteins containing NSD3 have also been reported in leukemia (NSD3-NUP98), and in NUT (nuclear protein of the testis) midline carcinoma (NSD3-NUT). Its role as an oncogene has been described by modulating different cancer pathways through its methyltransferase activity, or the short isoform of the protein, through protein interactions. Specifically, in this review we will focus on the functions that have been characterized as methyltransferase dependent, and those that have been correlated with the expression of the NSD3S isoform. There is evidence that both the NSD3L and NSD3S isoforms are relevant for cancer progression, establishing NSD3 as a therapeutic target. However, further functional studies are needed to differentiate NSD3 oncogenic activity as dependent or independent of the catalytic domain of the protein, as well as the contribution of each isoform and its clinical significance in cancer progression.

A. Epigenetic regulation of craniofacial development and disease

BACKGROUND

The formation of the craniofacial complex relies on proper neural crest development. The gene regulatory networks (GRNs) and signaling pathways orchestrating this process have been extensively studied. These GRNs and signaling cascades are tightly regulated as alterations to any stage of neural crest development can lead to common congenital birth defects, including multiple syndromes affecting facial morphology as well as nonsyndromic facial defects, such as cleft lip with or without cleft palate. Epigenetic factors add a hierarchy to the regulation of transcriptional networks and influence the spatiotemporal activation or repression of specific gene regulatory cascades; however less is known about their exact mechanisms in controlling precise gene regulation.

AIMS

In this review, we discuss the role of epigenetic factors during neural crest development, specifically during craniofacial development and how compromised activities of these regulators contribute to congenital defects that affect the craniofacial complex.

NSD2 as a Promising Target in Hematological Disorders

Alterations of the epigenetic machinery are critically involved in cancer development and maintenance; therefore, the proteins in charge of the generation of epigenetic modifications are being actively studied as potential targets for anticancer therapies. A very important and widespread epigenetic mark is the dimethylation of Histone 3 in Lysine 36 (H3K36me2). Until recently, it was considered as merely an intermediate towards the generation of the trimethylated form, but recent data support a more specific role in many aspects of genome regulation. H3K36 dimethylation is mainly carried out by proteins of the Nuclear SET Domain (NSD) family, among which NSD2 is one of the most relevant members with a key role in normal hematopoietic development. Consequently, NSD2 is frequently altered in several types of tumors—especially in hematological malignancies. Herein, we discuss the role of NSD2 in these pathological processes, and we review the most recent findings in the development of new compounds aimed against the oncogenic forms of this novel anticancer candidate.

Chick cranial neural crest cells release extracellular vesicles that are critical for their migration

The content and activity of extracellular vesicles purified from cell culture media or bodily fluids have been studied extensively; however, the physiological relevance of exosomes within normal biological systems is poorly characterized, particularly during development. Although exosomes released by invasive metastatic cells alter migration of neighboring cells in culture, it is unclear whether cancer cells misappropriate exosomes released by healthy differentiated cells or reactivate dormant developmental programs that include exosome cell-cell communication. Using chick cranial neural fold cultures, we show that migratory neural crest cells, a developmentally critical cell type and model for metastasis, release and deposit CD63-positive 30-100 nm particles into the extracellular environment. Neural crest cells contain ceramide-rich multivesicular bodies and produce larger vesicles positive for migrasome markers as well. We conclude that neural crest cells produce extracellular vesicles including exosomes and migrasomes. When Rab27a plasma membrane docking is inhibited, neural crest cells become less polarized and rounded, leading to a loss of directional migration and reduced speed. These results indicate that neural crest cell exosome release is critical for migration.

The role of NSD1, NSD2, and NSD3 histone methyltransferases in solid tumors

NSD1, NSD2, and NSD3 constitute the nuclear receptor-binding SET Domain (NSD) family of histone 3 lysine 36 (H3K36) methyltransferases. These structurally similar enzymes mono- and di-methylate H3K36, which contribute to the maintenance of chromatin integrity and regulate the expression of genes that control cell division, apoptosis, DNA repair, and epithelial-mesenchymal transition (EMT). Aberrant expression or mutation of members of the NSD family is associated with developmental defects and the occurrence of some types of cancer. In this review, we discuss the effect of alterations in NSDs on cancer patient's prognosis and response to treatment. We summarize the current understanding of the biological functions of NSD proteins, focusing on their activities and the role in the formation and progression in solid tumors biology, as well as how it depends on tumor etiologies. This review also discusses ongoing efforts to develop NSD inhibitors as a promising new class of cancer therapeutic agents.

The lysine methyltransferase SETD2 is a dynamically expressed regulator of early neural crest development

SETD2 is a histone H3 lysine 36 (H3K36) tri-methylase that is upregulated in response to neural crest induction. Because the H3K36 di-methylase NSD3 and cytoplasmic non-histone protein methylation are necessary for neural crest development, we investigated the expression and requirement for SETD2 in the neural crest. SetD2 is expressed throughout the chick blastoderm beginning at gastrulation. Subsequently, SetD2 mRNA becomes restricted to the neural plate, where it is strongly and dynamically expressed as neural tissue is regionalized and cell fate decisions are made. This includes expression in premigratory neural crest cells, which is downregulated prior to migration. Likely due to the early onset of its expression, SETD2 morpholino knockdown does not significantly alter premigratory Sox10 expression or neural crest migration; however, both are disrupted by a methyltransferase mutant SETD2 construct. These results suggest that SETD2 activity is essential for early neural crest development, further demonstrating that lysine methylation is an important mechanism regulating the neural crest.