Desensitization and acute tolerance are terms used to describe the attenuation of receptor responsiveness by prolonged or intermittent exposure to an agonist. Unlike desensitization of G protein-coupled receptors (GPCRs), which is commonly explained by steric hindrance caused by the β-arrestins that are translocated to the activated receptors, molecular mechanisms involved in the acute toleranc...

Transforming growth factor (TGF)-β family proteins form heteromeric complexes with transmembrane serine/threonine kinases referred to as type I and type II receptors. Ligand binding initiates a signaling cascade that generates a variety of cell type-specific phenotypes. Whereas numerous studies have investigated the regulatory activities controlling TGF-β signaling, there is relatively little i...

Activation of G protein-coupled receptors results in multiple waves of signaling that are mediated by heterotrimeric G proteins and the scaffolding proteins β-arrestin 1/2. Ligands can elicit full or subsets of cellular responses, a concept defined as ligand bias or functional selectivity. However, our current understanding of β-arrestin-mediated signaling is still very limited. Here we provide...

The amplitude of transforming growth factor-β (TGF-β) signal is tightly regulated to ensure appropriate physiological responses. As part of negative feedback loop SMAD7, a direct transcriptional target of downstream TGF-β signaling acts as a scaffold to recruit the E3 ligase SMURF2 to target the TGF-β receptor complex for ubiquitin-mediated degradation. Here, we identify the deubiquitinating en...

Steroid hormones are found to play a major role in the genesis and progression of mammary tumors. The aim of this study was to immunohistochemically detect the presence of estrogen receptor alpha (ER α ), estrogen receptor beta (ER β ), and progesterone receptor (PR) and also to study the association between these markers in 29 cases of benign (11) and malignant (18) canine mammary tumors. ER α...

Insulin, growth hormone (GH), and insulin-like growth factor-1 (IGF-1) play key roles in the regulation of β cell growth and function. Although β cells express the GH receptor, the direct effects of GH on β cells remain largely unknown. Here we have employed a rat insulin II promoter-driven (RIP-driven) Cre recombinase to disrupt the GH receptor in β cells (βGHRKO). βGHRKO mice fed a standard c...

Protein tyrosine phosphorylation is a ubiquitous, fundamental biochemical mechanism that regulates essential eukaryotic cellular functions. The level of tyrosine phosphorylation of specific proteins is finely tuned by the dynamic balance between protein tyrosine kinase and protein tyrosine phosphatase activities. Hepatocyte growth factor receptor (also known as Met), a receptor protein tyrosine...

In addition to their role in desensitization and internalization of G protein-coupled receptors (GPCRs), β-arrestins are essential scaffolds linking GPCRs to Erk1/2 signaling. However, their role in GPCR-operated Erk1/2 activation differs between GPCRs and the underlying mechanism remains poorly characterized. Here, we show that activation of serotonin 5-HT2C receptors, which engage Erk1/2 path...

Pancreatic cancer is a highly aggressive malignancy with limited treatment options. Type-I interferons (e.g. IFN-α/-β) have several anti-tumour activities. Over the past few years, clinical studies evaluating the effect of adjuvant IFN-α therapy in pancreatic cancer yielded equivocal results. Although IFN-α and -β act via the type-I IFN receptor, the role of the number of receptors present on t...