Protein polybromo-1 (PB1) also known as BRG1-associated factor 180 (BAF180) is a protein that in humans is encoded by the PBRM1 gene. [5] [6] [7]
Human PBRM1 is one of three unique components of the SWI/SNF-B (PBAF) chromatin-remodeling complex, which contains at least SMARCA4/BRG1, SMARCB1/SNF5/INI1/BAF47, ACTL6A/BAF53A or ACTL6B/BAF53B, SMARCE1/BAF57, SMARCD1/BAF60A, SMARCD2/BAF60B, and actin. [8] [9]
Chicken PB1 possesses 5 bromodomains, 2 bromo-adjacent homology (BAH) domains, and 1 truncated high-mobility group (HMG) motif. cPB1 is also homologous to yeast Rsc1, Rsc2, and Rsc4, essential proteins that are required for cell cycle progression through mitosis. [5]
PBRM1 is thought to be a tumor suppressor gene in many cancer subtypes largely due to the mutational pattern. [10] Most notably, mutations and copy number alterations in PBRM1 are highly prevalent in clear cell renal cell carcinoma (ccRCC). [11]
Loss of function mutations in PBRM1 often co-occur with loss of function mutations in the VHL gene in clear cell renal cell carcinoma (ccRCC). [12] The inactivation of PBRM1 in combination with biallelic loss of VHL has been shown to potentiate HIF1α signaling and activate the pro-tumorigenic NF-κB pathway. [13] [14] Genetic loss of PBRM1 is thought to underlie the early initiation of ccRCC due to the sufficiency of conditional deletion of Pbrm1 and Vhl for renal carcinomagenesis in mice. [15] While several studies have identified a favorable outcomes among advanced ccRCC cases with PBRM1 mutations when treated with immune checkpoint inhibitors, there is still debate about the utility of PBRM1 status as a biomarker for response to ICI therapy. [16] [17]
RSC is a member of the ATP-dependent chromatin remodeler family. The activity of the RSC complex allows for chromatin to be remodeled by altering the structure of the nucleosome.
In molecular biology, SWI/SNF, is a subfamily of ATP-dependent chromatin remodeling complexes, which is found in eukaryotes. In other words, it is a group of proteins that associate to remodel the way DNA is packaged. This complex is composed of several proteins – products of the SWI and SNF genes, as well as other polypeptides. It possesses a DNA-stimulated ATPase activity that can destabilize histone-DNA interactions in reconstituted nucleosomes in an ATP-dependent manner, though the exact nature of this structural change is unknown. The SWI/SNF subfamily provides crucial nucleosome rearrangement, which is seen as ejection and/or sliding. The movement of nucleosomes provides easier access to the chromatin, allowing genes to be activated or repressed.
Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression. Such remodeling is principally carried out by 1) covalent histone modifications by specific enzymes, e.g., histone acetyltransferases (HATs), deacetylases, methyltransferases, and kinases, and 2) ATP-dependent chromatin remodeling complexes which either move, eject or restructure nucleosomes. Besides actively regulating gene expression, dynamic remodeling of chromatin imparts an epigenetic regulatory role in several key biological processes, egg cells DNA replication and repair; apoptosis; chromosome segregation as well as development and pluripotency. Aberrations in chromatin remodeling proteins are found to be associated with human diseases, including cancer. Targeting chromatin remodeling pathways is currently evolving as a major therapeutic strategy in the treatment of several cancers.
Transcription activator BRG1 also known as ATP-dependent chromatin remodeler SMARCA4 is a protein that in humans is encoded by the SMARCA4 gene.
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 is a protein that in humans is encoded by the SMARCB1 gene.
Probable global transcription activator SNF2L2 is a protein that in humans is encoded by the SMARCA2 gene.
Actin-like protein 6A is a protein that in humans is encoded by the ACTL6A gene.
AT-rich interactive domain-containing protein 1A is a protein that in humans is encoded by the ARID1A gene.
SWI/SNF complex subunit SMARCC1 is a protein that in humans is encoded by the SMARCC1 gene.
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily E member 1 is a protein that in humans is encoded by the SMARCE1 gene.
SWI/SNF complex subunit SMARCC2 is a protein that in humans is encoded by the SMARCC2 gene.
AT-rich interactive domain-containing protein 1B is a protein that in humans is encoded by the ARID1B gene. ARID1B is a component of the human SWI/SNF chromatin remodeling complex.
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily D member 1 is a protein that in humans is encoded by the SMARCD1 gene.
AT-rich interactive domain-containing protein 2 (ARID2) is a protein that in humans is encoded by the ARID2 gene.
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily D member 3 is a protein that in humans is encoded by the SMARCD3 gene.
Probable global transcription activator SNF2L1 is a protein that in humans is encoded by the SMARCA1 gene.
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily D member 2 is a protein that in humans is encoded by the SMARCD2 gene.
TOX high mobility group box family member 3, also known as TOX3, is a human gene.
Diana Hargreaves is an American biologist and assistant professor at The Salk Institute for Biological Studies and member of The Salk Cancer Center. Her laboratory focuses on epigenetic regulation by the BAF (SWI/SNF) chromatin remodeling complexes in diverse physiological processes including development, immunity, and diseases such as cancer.
Cigall Kadoch is an American biochemist and cancer biologist who is Associate Professor of Pediatric Oncology at the Dana–Farber Cancer Institute and Harvard Medical School and an Investigator at the Howard Hughes Medical Institute. Her research is focused in chromatin regulation and how changes in cellular structure can lead to human diseases, such as Cancer, Neurodevelopmental disorders, and others. She is internationally recognized for her work on the mammalian SWI/SNF complex, a large molecular machine known as a Chromatin remodeling complex. She was named as one of the world's leading scientists by MIT Technology Review, 35 Under 35 and Forbes 30 Under 30, and a Finalist for the Blavatnik Awards for Young Scientists. In 2019, she received the Martin and Rose Wachtel Cancer Research Prize from the American Association for the Advancement of Science and in 2020, the American Association for Cancer Research Outstanding Achievement in Basic Cancer Research Award.