Paired box protein Pax-5 is a protein that in humans is encoded by the PAX5 gene. [5] [6] [7]
The PAX5 gene is a member of the paired box (PAX) family of transcription factors. The central feature of this gene family is a novel, highly conserved DNA-binding domain, known as the paired box. The PAX proteins are important regulators in early development, and alterations in the expression of their genes are thought to contribute to neoplastic transformation. The PAX5 gene encodes the B-cell lineage specific activator protein (BSAP) that is expressed at early, but not late stages of B-cell differentiation. Its expression has also been detected in developing CNS and testis, therefore, PAX5 gene product may not only play an important role in B-cell differentiation, but also in neural development and spermatogenesis. [7]
The PAX5 gene is located in chromosome 9p13 region, which is involved in t(9;14)(p13;q32) translocations recurring in small lymphocytic lymphomas of the plasmacytoid subtype, and in derived large-cell lymphomas. This translocation brings the potent E-mu enhancer of the IgH gene locus into close proximity of the PAX5 promoters, suggesting that the deregulation of PAX5 gene transcription contributes to the pathogenesis of these lymphomas. [7]
Up to 97% of the Reed–Sternberg cells of Hodgkin's lymphoma express Pax-5. [8]
PAX5 has been shown to interact with TLE4 [9] [10] and Death associated protein 6. [11]
Activation-induced cytidine deaminase, also known as AICDA, AID and single-stranded DNA cytosine deaminase, is a 24 kDa enzyme which in humans is encoded by the AICDA gene. It creates mutations in DNA by deamination of cytosine base, which turns it into uracil. In other words, it changes a C:G base pair into a U:G mismatch. The cell's DNA replication machinery recognizes the U as a T, and hence C:G is converted to a T:A base pair. During germinal center development of B lymphocytes, AID also generates other types of mutations, such as C:G to A:T. The mechanism by which these other mutations are created is not well understood. It is a member of the APOBEC family.
In evolutionary developmental biology, Paired box (Pax) genes are a family of genes coding for tissue specific transcription factors containing an N-terminal paired domain and usually a partial, or in the case of four family members, a complete homeodomain to the C-terminus. An octapeptide as well as a Pro-Ser-Thr-rich C terminus may also be present. Pax proteins are important in early animal development for the specification of specific tissues, as well as during epimorphic limb regeneration in animals capable of such.
The PAX3 gene encodes a member of the paired box or PAX family of transcription factors. The PAX family consists of nine human (PAX1-PAX9) and nine mouse (Pax1-Pax9) members arranged into four subfamilies. Human PAX3 and mouse Pax3 are present in a subfamily along with the highly homologous human PAX7 and mouse Pax7 genes. The human PAX3 gene is located in the 2q36.1 chromosomal region, and contains 10 exons within a 100 kb region.
B-lymphocyte antigen CD19, also known as CD19 molecule, B-Lymphocyte Surface Antigen B4, T-Cell Surface Antigen Leu-12 and CVID3 is a transmembrane protein that in humans is encoded by the gene CD19. In humans, CD19 is expressed in all B lineage cells. Contrary to some early doubts, human plasma cells do express CD19, as confirmed by others. CD19 plays two major roles in human B cells: on the one hand, it acts as an adaptor protein to recruit cytoplasmic signaling proteins to the membrane; on the other, it works within the CD19/CD21 complex to decrease the threshold for B cell receptor signaling pathways. Due to its presence on all B cells, it is a biomarker for B lymphocyte development, lymphoma diagnosis and can be utilized as a target for leukemia immunotherapies.
Bcl-6 is a protein that in humans is encoded by the BCL6 gene. BCL6 is a master transcription factor for regulation of T follicular helper cells proliferation. BCL6 has three evolutionary conserved structural domains. The interaction of these domains with corepressors allows for germinal center development and leads to B cell proliferation.
Nuclear factor of activated T-cells, cytoplasmic 2 is a protein that in humans is encoded by the NFATC2 gene.
Paired box gene 2, also known as Pax-2, is a protein which in humans is encoded by the PAX2 gene.
Cyclic AMP-dependent transcription factor ATF-1 is a protein that in humans is encoded by the ATF1 gene.
CD69 is a human transmembrane C-Type lectin protein encoded by the CD69 gene. It is an early activation marker that is expressed in hematopoietic stem cells, T cells, and many other cell types in the immune system. It is also implicated in T cell differentiation as well as lymphocyte retention in lymphoid organs.
Paired box gene 8, also known as PAX8, is a protein which in humans is encoded by the PAX8 gene.
DNA-binding protein Ikaros also known as Ikaros family zinc finger protein 1 is a protein that in humans is encoded by the IKZF1 gene.
ERG is an oncogene. ERG is a member of the ETS family of transcription factors. The ERG gene encodes for a protein, also called ERG, that functions as a transcriptional regulator. Genes in the ETS family regulate embryonic development, cell proliferation, differentiation, angiogenesis, inflammation, and apoptosis.
Interferon regulatory factor 4 (IRF4) also known as MUM1 is a protein that in humans is encoded by the IRF4 gene,. IRF4 functions as a key regulatory transcription factor in the development of human immune cells. The expression of IRF4 is essential for the differentiation of T lymphocytes and B lymphocytes as well as certain myeloid cells. Dysregulation of the IRF4 gene can result in IRF4 functioning either as an oncogene or a tumor-suppressor, depending on the context of the modification.
Nuclear factor of activated T-cells, cytoplasmic 3 is a protein that in humans is encoded by the NFATC3 gene.
PR domain zinc finger protein 1, or B lymphocyte-induced maturation protein-1 (BLIMP-1), is a protein in humans encoded by the gene PRDM1 located on chromosome 6q21. BLIMP-1 is considered a 'master regulator' of hematopoietic stem cells, and plays a critical role in the development of plasma B cells, T cells, dendritic cells (DCs), macrophages, and osteoclasts. Pattern Recognition Receptors (PRRs) can activate BLIMP-1, both as a direct target and through downstream activation. BLIMP-1 is a transcription factor that triggers expression of many downstream signaling cascades. As a fine-tuned and contextual rheostat of the immune system, BLIMP-1 up- or down-regulates immune responses depending on the precise scenarios. BLIMP-1 is highly expressed in exhausted T-cells – clones of dysfunctional T-cells with diminished functions due to chronic immune response against cancer, viral infections, or organ transplant.
Transcription factor COE1 is a protein that in humans is encoded by the EBF1 gene. EBF1 stands for Early B-Cell Factor 1.
Transducin-like enhancer protein 4 is a protein that in humans is encoded by the TLE4 gene.
Mucosa-associated lymphoid tissue lymphoma translocation protein 1 is a protein that in humans is encoded by the MALT1 gene. It's the human paracaspase.
The Interleukin-2 receptor alpha chain is a protein involved in the assembly of the high-affinity Interleukin-2 receptor, consisting of alpha (IL2RA), beta (IL2RB) and the common gamma chain (IL2RG). As the name indicates, this receptor interacts with Interleukin-2, a pleiotropic cytokine which plays an important role in immune homeostasis.
Meinrad Busslinger is a biochemist and immunologist, renown for his work on B cells. He is a Senior Scientist and Scientific Deputy Director of the Research Institute of Molecular Pathology (IMP) in Vienna, Austria.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.