Caspase recruitment domain-containing protein 11 also known as CARD-containing MAGUK protein 1 (Carma 1) is a protein in the CARD-CC protein family that in humans is encoded by the CARD11 gene. [5] [6] [7] CARD 11 is a membrane associated protein that is found in various human tissues, including the thymus, spleen, liver, and peripheral blood leukocytes. Similarly, CARD 11 is also found in abundance in various lines of cancer cells. [5]
The protein encoded by this gene belongs to the membrane-associated guanylate kinase (MAGUK) family, a class of proteins that functions as molecular scaffolds for the assembly of multiprotein complexes at specialized regions of the plasma membrane. This protein is also a member of the CARD protein family, which is defined by carrying a characteristic caspase-associated recruitment domain (CARD). CARD11 (CARMA1) has a domain structure similar to that of CARD10 (CARMA3) and CARD14 (CARMA2) as a member of the CARD-CC family with a C terminal MAGUK domain (the so-called CARMA proteins). The CARD domain of proteins in the CARD-CC family have been shown to specifically interact with BCL10, a protein known to function as a positive regulator of NF-κB activation by recruitment and activation of MALT1. When overexpressed in cells, this protein family activates NF-κB and induces the phosphorylation of BCL10. [7]
CARD11 is critical for T cell and B cell function and is activated after T cell receptor or B cell receptor stimulation. After receptor stimulation, CARD11 is phosphorylated by PKC-θ (in T cells) or PKC-β (in B cells). The phosphorylation induces formation of filamentous CARD11 multimers that recruit BCL10 and MALT1, which in turn activates NF-κB. Loss of function mutations in CARD11 cause severe combined immunodeficiency (SCID) since the function of cells critical for adaptive immunity are disrupted.
The structure of CARD11 involves multiple domains that impact the protein's ability to activate BCL10 and NF-κB activity. CARD11 has a CARD domain, a serine-threonine rich region, is associated with the N-terminus, which is essential for NF-κB signaling activity. The region following the CARD domain is highly coiled. In deleting the CARD domain, all NF-κB signaling activity was prevented. The CARD domain on CARD11 interacts with the CARD domain on BCL10 to initiate the signaling pathway. [5]
On the C-terminus of CARD11 there is the MAGUK domain that is associated with the cell membrane. This domain is often referred to as the inhibitory domain. Protein kinase C activates CARD11 by phosphorylating serine residues within the inhibitory domain. [5] [8]
CARD11 has been shown to interact with BCL10. [9] This interaction occurs between the CARD domain on BCL10 and the CARD domain on CARD11, and results in signal propagation and NF-κB activation. [8]
Caspase recruitment domains, or caspase activation and recruitment domains (CARDs), are interaction motifs found in a wide array of proteins, typically those involved in processes relating to inflammation and apoptosis. These domains mediate the formation of larger protein complexes via direct interactions between individual CARDs. CARDs are found on a strikingly wide range of proteins, including helicases, kinases, mitochondrial proteins, caspases, and other cytoplasmic factors.
The B-cell receptor (BCR) is a transmembrane protein on the surface of a B cell. A B-cell receptor is composed of a membrane-bound immunoglobulin molecule and a signal transduction moiety. The former forms a type 1 transmembrane receptor protein, and is typically located on the outer surface of these lymphocyte cells. Through biochemical signaling and by physically acquiring antigens from the immune synapses, the BCR controls the activation of the B cell. B cells are able to gather and grab antigens by engaging biochemical modules for receptor clustering, cell spreading, generation of pulling forces, and receptor transport, which eventually culminates in endocytosis and antigen presentation. B cells' mechanical activity adheres to a pattern of negative and positive feedbacks that regulate the quantity of removed antigen by manipulating the dynamic of BCR–antigen bonds directly. Particularly, grouping and spreading increase the relation of antigen with BCR, thereby proving sensitivity and amplification. On the other hand, pulling forces delinks the antigen from the BCR, thus testing the quality of antigen binding.
NF-kappa-B essential modulator (NEMO) also known as inhibitor of nuclear factor kappa-B kinase subunit gamma (IKK-γ) is a protein that in humans is encoded by the IKBKG gene. NEMO is a subunit of the IκB kinase complex that activates NF-κB. The human gene for IKBKG is located on the chromosome band Xq28. Multiple transcript variants encoding different isoforms have been found for this gene.
Caspase-8 is a caspase protein, encoded by the CASP8 gene. It most likely acts upon caspase-3. CASP8 orthologs have been identified in numerous mammals for which complete genome data are available. These unique orthologs are also present in birds.
TNF receptor-associated factor 2 is a protein that in humans is encoded by the TRAF2 gene.
IKK-β also known as inhibitor of nuclear factor kappa-B kinase subunit beta is a protein that in humans is encoded by the IKBKB gene.
Transcription factor p65 also known as nuclear factor NF-kappa-B p65 subunit is a protein that in humans is encoded by the RELA gene.
Inhibitor of nuclear factor kappa-B kinase subunit alpha (IKK-α) also known as IKK1 or conserved helix-loop-helix ubiquitous kinase (CHUK) is a protein kinase that in humans is encoded by the CHUK gene. IKK-α is part of the IκB kinase complex that plays an important role in regulating the NF-κB transcription factor. However, IKK-α has many additional cellular targets, and is thought to function independently of the NF-κB pathway to regulate epidermal differentiation.
Protein kinase C theta (PKC-θ) is an enzyme that in humans is encoded by the PRKCQ gene. PKC-θ, a member of serine/threonine kinases, is mainly expressed in hematopoietic cells with high levels in platelets and T lymphocytes, where plays a role in signal transduction. Different subpopulations of T cells vary in their requirements of PKC-θ, therefore PKC-θ is considered as a potential target for inhibitors in the context of immunotherapy.
B-cell lymphoma/leukemia 10 is a protein that in humans is encoded by the BCL10 gene. Like BCL2, BCL3, BCL5, BCL6, BCL7A, and BCL9, it has clinical significance in lymphoma.
Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) functions in a variety of cellular pathways related to both cell survival and death. In terms of cell death, RIPK1 plays a role in apoptosis and necroptosis. Some of the cell survival pathways RIPK1 participates in include NF-κB, Akt, and JNK.
Tumor necrosis factor, alpha-induced protein 3 or A20 is a protein that in humans is encoded by the TNFAIP3 gene.
Receptor-interacting serine/threonine-protein kinase 2 is an enzyme that in humans is encoded by the RIPK2 gene.
Mitogen-activated protein kinase kinase kinase 14 also known as NF-kappa-B-inducing kinase (NIK) is an enzyme that in humans is encoded by the MAP3K14 gene.
Caspase recruitment domain-containing protein 10 is a protein in the CARD-CC protein family that in humans is encoded by the CARD10 gene.
Caspase recruitment domain-containing protein 9 is an adaptor protein of the CARD-CC protein family, which in humans is encoded by the CARD9 gene. It mediates signals from pattern recognition receptors to activate pro-inflammatory and anti-inflammatory cytokines, regulating inflammation. Homozygous mutations in CARD9 are associated with defective innate immunity against yeasts, like Candida and dermatophytes.
The nucleotide-binding oligomerization domain-like receptors, or NOD-like receptors (NLRs), are intracellular sensors of pathogen-associated molecular patterns (PAMPs) that enter the cell via phagocytosis or pores, and damage-associated molecular patterns (DAMPs) that are associated with cell stress. They are types of pattern recognition receptors (PRRs), and play key roles in the regulation of innate immune response. NLRs can cooperate with toll-like receptors (TLRs) and regulate inflammatory and apoptotic response.
Caspase recruitment domain-containing protein 14, also known as D-containing MAGUK protein 2, is a protein in the CARD-CC protein family that in humans is encoded by the CARD14 gene.
Bcl10-interacting CARD protein, also known as BinCARD, is a protein that in humans is encoded by the C9orf89 gene on chromosome 9. BinCARD is a member of the death-domain superfamily and contains a caspase recruitment domain (CARD). This protein regulates apoptosis and the immune response by inhibiting Bcl10, thus implicating it in diseases stemming from Bcl10 dysfunction.
The CARD-CC protein family is defined by an evolutionary conserved "caspase activation and recruitment domain" (CARD) and a coiled-coil (CC) domain. Coiled-coils (CC) act as oligomerization domains for many proteins such as structural and motor proteins, and transcription factors. This means that monomers are converted to macromolecular complexes by polymerization. In humans and other jawed vertebrates, the family consists of CARD9 and the three "CARD-containing MAGUK protein" (CARMA) proteins CARD11 (CARMA1), CARD14 (CARMA2) and CARD10 (CARMA3). Although the MAGUK protein DLG5 contains both a CARD domain and a CC domain, it does not belong to the same family as the CARD-CC proteins since the evolutionary origin of its CARD domain is very likely to be different.
