Functional Assays

PARP1, also known as poly-(ADP-ribose) polymerase 1 or NAD⁺ ADP-ribosyltransferase 1, is part of the PARP family, and it is the most abundant member.  ADP ribosylation, which is the addition of an ADP-ribose to a protein, is a reversible post-translational modification of proteins mostly involved in the DNA Damage Response (DDR) pathway. Poly-ADP-ribosylation (termed PARylation) is the addition of linear or branched chains of ADP-ribose. PARP1 participates in DNA repair by non-homologous end joining (NHEJ), homologous recombination (HR), microhomology-mediated end-joining (MMEJ) and nucleotide excision repair. Dysfunction of DDR pathways can lead to oncogenesis. Overexpression of PARP1 has been found in breast and colon cancer, neuroblastoma, and others. This overexpression can lead to increasing MMEJ, an error-prone DNA repair mechanism, and genome instability leading to cancer. In addition to being involved in DDR, PARP1 is also linked to inflammation and type I diabetes.

PARP2, also known as poly-(ADP-ribose) polymerase 2 or NAD⁺ ADP-ribosyltransferase 2, is part of the PARP family. ADP ribosylation, which is the addition of an ADP-ribose to a protein, is a reversible post-translational modification of proteins mostly involved in the DNA Damage Response (DDR) pathway. Poly-ADP-ribosylation (termed PARylation) is the addition of linear or branched chains of ADP-ribose. PARP2 participates in DNA repair (only 10% of total PARP activity is due to PARP2), but also in oxidative stress and mitochondrial fragmentation. Dysfunction of the DDR and oxidative stress pathways can lead to oncogenesis. Genetic ablation of PARP2 has indicated roles of PARP2 in adipogenesis, spermatogenesis and thymocyte survival. It is also a co-factor of nuclear receptors like ER (estrogen receptor) and PPAR (peroxisome proliferator-activated receptors). PARP2 is overexpressed in prostate cancer and may contribute to the disease through the FOXA1 (forkhead box protein A1)/

The CDK12/CyclinK complex comprises human CDK12 (cyclin dependent kinase 12) and human cyclinK. CDK12 is ubiquitously expressed, being present at high levels in the reproductive tissues, endocrine tissues, bone marrow and lymph nodes, predominantly in the nucleus of cells. CDK12 is involved in gene expression, transcription elongation and genome stability. CDK12 binds only to cyclinK, and the formation of this complex seems important to maintain cyclinK stability. This complex regulates phosphorylation of serine 2 in the C-terminal domain of RNA polymerase II, which is responsible for transcriptional elongation and synthesis of full-length mature mRNAs. However, lack of CDK12 seems to only affect about 5% or less of the total transcription, indicating a selective role of this complex in the transcription of certain genes. The use of inhibitors, such as THZ531, indicated that the genes being selectively regulated by CDK12/cyclinK are the core DDR (DNA damage and repair) genes. CDK12 pla

Bruton€™s tyrosine kinase or BTK, is a non-receptor kinase protein found in hematopoietic and plasma cells. It is involved in functionality, maturation, and apoptosis of B cells, in addition to regulating signals in the MAPK (mitogen-activated protein kinase), PI3K (phosphoinositide 3-kinase) and NF-κB (nuclear factor kappa B) pathways. The BTK pathway has implications for a number of autoimmune disorders including isolated growth hormone deficiency type III and rheumatoid arthritis. BTK inhibitors have been used in the treatment of inflammatory diseases and hematological disorders including cancer. For instance, Ibrutinib (also known as PCI-32765), is used in the clinic for the treatment of CLL (chronic lymphocytic leukemia), MCL (mantle cell lymphoma) and GvHD (graft versus host disease) and other diseases. However, low-selectivity BTK inhibitors have severe side effects, so further refinement is necessary. Development of highly selective BTK inhibitors will lead to greater benefits

Protein Mixed Lineage Leukemia-1 (MLL1, also known as KMT2A) belongs to the SET1/MLL family which consists of six (MLL1-4/KMT2A-2D, SET1A/KMT2F, and SET1B/KMT2G) major methyltransferases in mammals. MLL1 is a histone-H3 lysine-4 (H3K4) methyltransferase that promotes H3K4 mono-/di-/tri-methylation, a conserved trait of euchromatin associated with transcriptional activation. MLL1 is a master regulator for the transcription of many important genes including homeobox (Hox), which has been implicated in hematopoiesis and embryonic development. MLL1 forms a complex with RbBP5 (retinoblastoma-binding protein 5), ASH2L (Absent, small, homeotic disks-2-like), WDR5 (WD40 repeat-containing protein 5), and DPY30 (DumPY protein 30) to catalyze tri-methylation of H3K4. WDR5 represents a therapeutically exploitable target for cancer treatment as it plays a crucial role in MLL1 complex assembly and disassembly. WDR5 has two protein interaction sites: the WDR5-interacting (WIN) binding site and the WD

The Mixed Lineage Leukemia-4 (MLL4, also known as KMT2B) protein belongs to the SET1/MLL family which consists of six (MLL1-4/KMT2A-2D, SET1A/KMT2F, and SET1B/KMT2G) major methyltransferases in mammals. MLL4 is a histone-H3 lysine-4 (H3K4) methyltransferase that promotes H3K4 mono-/di-/tri-methylation, a conserved trait of euchromatin associated with transcriptional activation. MLL4 is a critical player in memory formation. MLL4 forms a complex with RbBP5 (retinoblastoma-binding protein 5), ASH2L (Absent, small, homeotic disks-2-like), WDR5 (WD40 repeat-containing protein 5), and DPY30 (DumPY protein 30) to catalyze methylation of H3K4. WDR5 represents a therapeutically exploitable target for cancer treatment as it plays a crucial role in MLL1 complex assembly and disassembly. WDR5 has two protein interaction sites: the WDR5-interacting (WIN) binding site and the WDR5-binding-motif (WBM) site. MLL1-4 forms the complex via WIN binding site, while RbBP5 is bound to WBM site, which is als

EGFR (epidermal growth factor receptor), also known as ERBB-1 and HER1, is the cell-surface tyrosine kinase receptor for members of the epidermal growth factor family. Its ligands include EGF, TGFα (transforming growth factor alpha), HB-EGF (heparin-binding EGF), betacellulin, amphiregulin, epiregulin and epigen. EGFR exists as an inactive monomer until it gets activated. Upon ligand binding it forms an asymmetric dimer, for instance with HER2 (human epidermal growth factor receptor 2), which induces autophosphorylation, creating binding sites for adaptor proteins such as GRB2 (growth factor receptor-bound protein 2) and/or CBL (Casitas B-lineage lymphoma). EGFR can bind to several adaptor proteins simultaneously and thus activate multiple positive and negative signaling pathways. Overexpression and/or hyperactivation of EGFR kinase is associated with several human cancers such as lung, glioblastoma (GBM), and epithelial tumors of the neck and head, being the most common mutation in GB

TSLP (thymic stromal lymphopoietin) is a protein that functions as a type I cytokine, as an alarmin and growth factor in the immune system. It is involved in type 2 immune responses, T_H2 (T helper 2 cells) responses, and the maturation and recruitment of dendritic cells (DCs), T cells, B cells, neutrophils, mast cells, and other lymphoid cells.  It can be produced by epithelial and stromal cells in lung, skin, and gastric system, but also by DCs, basophils and mast cells. Its expression can be induced by infections, pro-inflammatory cytokines, proteases, and even mechanical injury. For instance, it can be produced in the lungs in response to infection with influenza or rhinovirus. Its role as alarmin can result in increasing inflammation. TSLP is linked to allergic reactions such as asthma, atopic dermatitis, and food allergies, by inducing the expression of OX40L, CD80 and CD86 and stimulating CD4⁺T cells. In 2021, the TLSP-neutralizing antibody tezepelumab was

The BLM helicase, also known as Bloom syndrome protein, is a key enzyme involved in DNA replication and repair (DDR). The BLM helicase is a member of the RecQ family of helicases, which are evolutionarily conserved and found in many organisms, including bacteria, yeast, and humans. It catalyzes the unwinding of duplex DNA with 3' to 5' directionality, driven by the energy generated from ATP hydrolysis. BLM plays a crucial role in maintaining genomic stability by unwinding DNA structures during processes such as DNA replication, recombination, and repair. Mutations in the BLM gene can lead to Bloom syndrome, a rare genetic disorder characterized by growth deficiency, sun-sensitive skin lesions, and an increased risk of cancer. High expression of BLM is found in glioblastoma, and it was found that inhibition of its activity leads to increased susceptibility to treatment with drugs targeting other proteins involved in DDR, such as PARP1 (poly-ADP ribosylation protein 1). The use of BLM in