The readout of histone modifications plays a critical role in chromatin-regulated processes. Dimethylation at Lys-36 on histone H3 (H3K36me2) is associated with actively transcribed genes, and global up-regulation of this modification is associated with several cancers. However, the molecular mechanism by which H3K36me2 is sensed and transduced to downstream biological outcomes remains unclear. Here we identify a PWWP domain within the histone lysine methyltransferase and oncoprotein NSD2 that preferentially binds to nucleosomes containing H3K36me2. In cells, the NSD2 PWWP domain interaction with H3K36me2 plays a role in stabilizing NSD2 at chromatin. Furthermore, NSD2's ability to induce global increases in H3K36me2 via its enzymatic activity, and consequently promote cellular proliferation, is compromised by mutations within the PWWP domain that specifically abrogate H3K36me2-recognition. Together, our results identify a pivotal role for NSD2 binding to its catalytic product in regulating its cellular functions, and suggest a model for how this interaction may facilitate epigenetic spreading and propagation of H3K36me2.Chromatin dynamics play a critical role in the regulation of diverse cellular functions, the dysregulation of which is linked to the development and progression of human diseases. A major mechanism for regulating chromatin functional states involves the reversible covalent post-translational modification of histone proteins by chemical moieties such as methyl-, acetyl-, and phospho-groups. Histones provide a highly modifiable signaling surface on which these chemical marks combine to define particular chromatin states and regulate the extent of accessibility of DNA to trans-acting factors. In this context, the proteins and domains that recognize histone modification fundamentally influence DNA-templated processes, transducing molecular events at chromatin to biological outcomes. Protein lysine methylation is a principal chromatin-regulatory mechanism. The chemical addition of methyl moieties to lysine residues is catalyzed by lysine methyltransferases (KMTs).3 Lysine residues can accept up to three methyl groups forming mono-, di-, and tri-methylated derivatives (referred to as me1, me2, and me3, respectively). Histone methylation has been linked via methyllysine-binding proteins to diverse processes, including transcription, DNA recombination, DNA repair, and DNA replication.Methylation of histone H3 at lysine 36 (H3K36) is found at gene bodies of actively transcribed genes, but the state of methylation at this residue defines distinct biological outcomes. Trimethylation of this site (H3K36me3), which is mediated by the KMT SETD2 in humans, is involved in splicing regulation, RNA processing, and DNA damage signaling (1-7). Loss of SETD2 and H3K36me3 is a recurring phenomenon in clear cell renal cell carcinoma (ccRCC) and other cancers, suggesting a tumor suppressor role for SETD2 (8 -10). In contrast, the specific molecular functions associated with H3K36me2 are unclear. However, elevated level...

Background: SETMAR is a lysine methyltransferase (KMT) that contributes to DNA repair, but its biochemical function is not well understood. Results: A novel proteomic strategy identifies splicing factor snRNP70 as a SETMAR substrate. Conclusion: SETMAR is the first KMT identified to target splicing factors. Significance: Proteomics can be harnessed to discover methyltransferase substrates. Lysine methylation may be a new mode of regulation for mRNA splicing.

In introductory laboratory courses, many universities are turning from traditional laboratories with predictable outcomes to inquiry-inspired, project-based laboratory curricula. In these labs, students are allowed to design at least some portion of their own experiment and interpret new, undiscovered data. We have redesigned the introductory biology laboratory course at Brandeis University into a semester-long project-based laboratory that emphasizes concepts and contains an element of scientific inquiry. In this laboratory, students perform a site-directed mutagenesis experiment on the gene encoding human γD crystallin, a human eye lens protein implicated in cataracts, and assess the stability of their newly created protein with respect to wild-type crystallin. This laboratory utilizes basic techniques in molecular biology to emphasize the importance of connections between DNA and protein. This project lab has helped engage students in their own learning, has improved students’ skills in critical thinking and analysis, and has promoted interest in basic research in biology.

Recurrent mutations at key lysine residues in the histone variant H3.3 are thought to play an etiologic role in the development of distinct subsets of pediatric gliomas and bone and cartilage cancers. H3.3K36M is one such mutation that was originally identified in chondroblastomas, and its expression in these tumors contributes to oncogenic reprogramming by triggering global depletion of dimethylation and trimethylation at H3K36 with a concomitant increase in the levels of H3K27 trimethylation. H3.3K36M expression can also cause epigenomic changes in cell types beyond chondrocytic cells. Here we show that expression of H3.3K36M in HT1080 fibrosarcoma cancer cells severely impairs cellular proliferation, which contrasts its role in promoting transformation of chondrocytic cells. H3.3K36M-associated cellular toxicity phenocopies the specific depletion of H3K36me2, but not loss of H3K36me3. We further find that the H3K36me2-associated toxicity is largely independent of changes in H3K27me3. Together, our findings lend support to the argument that H3K36me2 has distinct roles in cancer cells independent of H3K36me3 and H3K27me3, and highlight the use of H3.3K36M as an epigenetic tool to study H3K36 and H3K27 methylation dynamics in diverse cell types.

Purpose With the United States Medical Licensing Examination Step 1 transition to pass/fail in 2022, uncertainty exists regarding how other residency application components, including research conducted during medical school, will inform interview and ranking decisions. The authors explore program director (PD) views on medical student research, the importance of disseminating that work, and the translatable skill set of research participation. Method Surveys were distributed to all U.S. residency PDs and remained open from August to November 2021 to query the importance of research participation in assessing applicants, whether certain types of research were more valued, productivity measures that reflect meaningful research participation, and traits for which research serves as a proxy. The survey also queried whether research would be more important without a numeric Step 1 score and the importance of research vs other application components.