Assembly and interaction of core subunits of BAF complexes and crystal study of the SMARCC1/SMARCE1 binary complex

Treatment of gouty lumbar spinal stenosis: a case report and bioinformatics analysis

The case of Lumbar spinal stenosis (LSS) combined with tophi due to gout is rarely reported. In the course of our clinic work, we encountered a young male patient who was diagnosed with a history of gout for 5 years and was targeted as LSS combined with gouty tophi, and we would like to share this case. In addition, in order to further investigate the deep mechanism of LSS associated with gout, we obtained the intersecting genes of the two diseases based on a machine learning approach by obtaining the dataset GSE113212 related to LSS from the Gene Expression Omnibus (GEO) database, and the genes related to gout from the human gene database. We found that TGFB1, PPARG, and SAMRCC1 may be important biomarkers for treating of both diseases. From a clinical perspective, clinicians should be vigilant about the possibility of gouty lumbar spinal stenosis with tophi in young patients presenting with back pain, hyperuricemia, and elevated inflammatory markers. A combined surgical and pharmacological treatment plan has a favorable prognosis. Investigating the mechanisms of action of core genes may provide new insights for treatment, ultimately leading to the development of comprehensive and personalized diagnostic and therapeutic strategies.

Identification of assembly mode of non-canonical BAF (ncBAF) chromatin remodeling complex core module

Mammalian SWI/SNF (mSWI/SNF) ATP-dependent chromatin remodeling complexes play critical roles in regulating gene expression and DNA accessibility, and more than 20 % of cancers have mutations in genes encoding chromatin remodeling complexes. The mSWI/SNF family comprises three distinct classes: canonical BAF (cBAF), PBAF, and non-canonical BAF (ncBAF). While the structures of cBAF and PBAF have been resolved by using cryo-electron microscopy (cryo-EM), the modular organization and assembly mechanism of ncBAF remain poorly understood. In this study, we first mapped the binding fragment of SMARCC1/SMARCD1 complex, then found that GLTSCR1(1041-1204) could form a stable complex with SMARCC1(447-966)/SMARCD1(129-515). Next, we purified the SMARCC1(447-966)/SMARCD1(117-515)/GLTSCR1(1041-1204)/BRD9(266-510) tetrameric complex. Finally, we assembled a stable and uniform SMARCC1(447-966)/SMARCD1(117-515)/GLTSCR1(1041-1204)/BRD9(266-510)/SMARCA4(289-464) quinary complex in vitro, which is ncBAF core module. These findings provide insight into the assembly mode of ncBAF complex, and lay the foundations for further solving its structure in the future.

(mis)-Targeting of SWI/SNF complex(es) in cancer

The ATP-dependent chromatin remodeling complex SWI/SNF (also called BAF) is critical for the regulation of gene expression. During the evolution from yeast to mammals, the BAF complex has evolved an enormous complexity that contains a high number of subunits encoded by various genes. Emerging studies highlight the frequent involvement of altered mammalian SWI/SNF chromatin-remodeling complexes in human cancers. Here, we discuss the recent advances in determining the structure of SWI/SNF complexes, highlight the mechanisms by which mutations affecting these complexes promote cancer, and describe the promising emerging opportunities for targeted therapies.

Commentary on: SMARCB1 as a novel diagnostic and prognostic biomarker for osteosarcoma

In the last couple of decades, biomarkers have been on the rise for diagnostic and predictive value. There has been a rush to identify new markers using new technologies and drug repurposing approaches. SMARCB1 acronym arises from the SWI/SNF (SWItch/Sucrose Non-Fermentable)-related Matrix-associated Actin-dependent Regulator of Chromatin subfamily B member 1 (SMARCB1). It is a molecule, whose role is associated with the sucrose metabolism. SMARCB1 is also called INI1 (Integrase Interactor 1). The molecule was discovered in the mid-1990s. Its role as a loss-of-function marker for malignant rhabdoid tumors (MRT) of renal and extrarenal origin has enormously expanded the spectrum of involved neoplasms since that time. Several tumors have been characterized by genetic aberrations in the SMARCB1 gene. They include reduction in expression, loss of expression, and mosaic expression. Most of the tumors are sarcomas, but a variegated group of tumors with mixed phenotypes has also been delineated. It is well known that the outcome of patients harboring genetic aberrations in the SMARCB1 gene has been poor. Guo et al. reported that reduced SMARCB1 expression occurred in 70% of osteosarcomas. Their data significantly correlated with poor neoadjuvant response. These authors emphasize a shorter progression-free and overall survival of the patients demonstrating an altered expression of this gene. Interestingly, mRNA in silico analysis established that SMARCB1 expression correlates with the response to chemotherapy of osteosarcoma patients, but there was no reliable correlation between SMARCB1 expression level and metastasis, response to neoadjuvant therapy, overall survival, and progression-free survival. The study involved a tissue microarray (TMA) on bone tumors that may limit the full evaluation of the gene expression. Nevertheless, Guo et al.'s study is remarkable. It expands the list of the tumors harboring an altered SMARCB1 gene expression and suggests that this marker should be investigated in every pathology workup for potential predictive value. On the other side, much work needs to be done if we hope that we strive to provide additional therapeutic strategies for osteosarcoma patients with altered SMARCB1 gene expression.