beta-catenin in signal transduction

Catenin


β-Catenin is a multifunctional adaptor protein involved in cadherin-mediated cell–cell adhesion and in responding to the activation of several signal transduction pathways, including Wnts, Akt/protein kinase B, epidermal growth factor (EGF), insulin-like growth factor, integrin-linked kinase, nuclear factor-κB, p53, Pin1, PTEN, FP(B) prostanoid receptor, nuclear hormone receptors such as peroxisome proliferator-activated receptors (PPARs), androgen receptor (AR) and retinoic acid receptor (RAR), and oxidative stress. Its role is best characterized in the canonical Wnt signaling pathway. On a Wnt signal, β-catenin accumulates in the nucleus and binds to transcription factors of the high-mobility-group (HMG) box Tcf/Lef family to stimulate downstream gene expression. Both the amino-terminal and carboxy-terminal regions mediate transcriptional activation, but the most potent activation domain resides at the C terminus. Direct target genes include c-myc, cyclin D1, c-jun, Tcf-1, Lef-1, Conductin/Axin2, and the metalloproteinase matrilysin (MMP7). The Wnt/β-catenin pathway has central functions in embryonic development, and perturbations in this pathway are linked to a variety of human diseases, most notably cancer. Remarkably, more than 90% of colorectal cancer patients carry an activating mutation in this pathway, including loss-of-function mutations in adenomatous polyposis coli (APC) and Axin, or gain-of-function mutations in β-catenin itself. More recently, β-catenin signaling has been implicated in the maintenance and self-renewal of stem or progenitor cells in various tissues including skin, blood, and gut.

Alternative names for this molecule: beta-Catenin; Catenin (cadherin-associated protein), beta 1 (88kD); Catenin beta; Catenin, beta; Catnb; Ctnnb; CTNNB1; Ctnnb1
Transition Network Graph

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DLK the master of biological processes

DLK

Dual leucine zipper-bearing kinase (DLK) is a member of the mixed-lineage kinase (MLK) subfamily of serine/threonine kinases, an important upstream component of the mitogen-activated protein kinase (MAPK) pathways. The DLK gene is expressed in a tissue-specific manner and its targeted deletion in mice causes perinatal death with defects in brain development. Recent analyses of mice, flies and worms bearing loss-of-functions mutations in either DLK or its invertebrate orthologs also demonstrated that this enzyme has a central role in the neuronal response to injury, being required for axon regeneration or degeneration depending on the species. Additionally, using overexpression and knockdown approaches, it was shown that DLK has pro-differentiation and pro-apoptotic effects in mammalian cells. Although little is known about how DLK is activated and modulated, accumulating evidence suggests a complex regulation that involves phosphorylation, interactions with different protein partners and ubiquitin-mediated degradation. Thus, DLK seems to be a key regulator for various fundamental biological processes, although the precise molecular mechanisms by which it mediates such effects remain to be determined.

Alternative names for this molecule: DLK; Dual leucine zipper bearing kinase; Dual leucine zipper-bearing kinase; MAP kinase upstream kinase; Map3k12; Mitogen activated protein kinase kinase kinase 12; Mitogen-activated protein kinase kinase kinase 12; MUK; Zipper protein kinase; ZPK