Activation induced cell death (AICD) of T lymphocytes plays a vital role in the regulation of the immune response. Cellular resistance to apoptosis can contribute to cancer and autoimmune diseases. Vasoactive intestinal peptide receptor 1 and 2 (VPAC1/2) are G‐protein coupled receptors highly expressed in the immune system that bind vasoactive intestinal peptide (VIP). It has been previously shown that inducible VPAC2 inhibits apoptosis in Th2 polarized CD4 T cells. However, the effect of VPAC1 signaling is not well understood. Naïve and activated HuT 78 cells, a transformed human T lymphocyte cell line predominantly expressing VPAC1, were treated +/‐ VIP. The extent of apoptosis was measured using a histone fragmentation‐based ELISA. In activated cells, VIP had little effect on apoptosis (10‐6‐10‐10M), but caused a significant increase in apoptosis in naïve cells (10‐8M). VIP/VPAC1 signaling induces apoptosis in naïve T cells but has little effect on activated cells. Furthermore, it appears that the VPAC1 and VPAC2 receptors affect apoptosis in opposing ways, most likely due to subtle differences in intracellular signaling. Research supported by NIH‐K01 1K01DK064828 and COBRE 2P20RR05566.
Background: Vasoactive intestinal peptide (VIP) is a 3.3 kDa pleiotropic protein with a broad expression profile that displays immune modulating activities. VIP binds two G protein-coupled receptors called Vasoactive Intestinal Pepide/Pituitary Adenylate Cyclase activating polypeptide receptor (VPAC) 1 and 2 that elicit multiple downstream signaling molecules, including adenylate cyclase. VIP differentially regulates over 300 genes in resting and activated murine CD4 T cells, and is chemotactic to resting and Th2 effector T cells. Keywords: cAMP, chemotaxis, gene expression, signaling, T cells, vasoactive intestinal peptide.
Ikaros (IK) is a krupple‐like zinc finger and master regulator of lymphopoesis. Mutations to the IK DNA binding domain result in T cell leukemia. The phosphorylated posttranslational modifications of IK have been shown to be regulated by casein kinase II (CKII) throughout the primary sequence. Putative consensus sequences for additional kinases such as GSK3, Cdk, CaMKII, and PKA have been identified. Hyperphosphorylation of IK reduces its DNA binding affinity and mediates G1/S transition. Vasoactive intestinal peptide/pituitary adenylyl cyclase activating peptide receptor 1 (VPAC1) is a G protein coupled receptor that negatively regulates T cell receptor (TCR) activation through a cAMP/PKA signaling dependent pathway when bound by its ligand, vasoactive intestinal peptide (VIP). Our hypothesis is that VIP/VPAC1 signaling suppresses CKII phosphorylation of IK in a PKA dependent mechanism. Upon T cell activation, a new immunoreactive pool of IK was detected, and VIP (10‐8M) ablated the detection of this hyperphosphorylated species. We conclude that VIP/VPAC1 signaling may block the immunoreactive pool of a certain hyperphosphorylated IK species thereby negatively regulating T cell activation. Research supported by NIH‐K01 1K01DK064828 and COBRE 2P20RR05566.
nurses and about half additionally accepted availability through own initiative, in print or through the Internet. Preference of timing was highly variable. Better acceptability, usefulness, and availability through own initiative were independently associated with non-Italian nationality, presence of more physical signs discussed in the booklet, feeling illprepared, and higher satisfaction with care. A preference of receiving the booklet early was more likely in Italian families, those without university education, and those involved with older residents. Conclusion: The booklet is suitable to inform Dutch and Canadian families on comfort care in dementia, but implementation in Italy requires further consideration. The booklet may be integrated in advance care planning in long-term care, and made available outside long-term care settings to serve families who wish to be informed early. (J Am Med Dir Assoc 2011; -: -–-)
Presently, Leukemia affects about 250,000 people in America and it is expected that 45,000 new cases will be diagnosed in 2009. We have previously published that Ikaros (IK), a tumor suppressor, downregulates vasoactive intestinal receptor 1 (VPAC1), an anti‐proliferative G protein coupled receptor, mediated by IK engagement to VPAC1. Currently, it is not known how post‐translational modifications, such as phosphorylation, regulate IK DNA binding activity. Therefore, we hypothesized that inhibition of casein kinase II, CKII, known to phosphorylate IK, would shift the equilibrium to favor its dephosphorylated IK state, causing greater DNA binding and repression of VPAC1. To test this, HuT‐78 cells were cultured in the presence and absence of 5,6‐dichloro‐1‐β‐D‐ribofuranosylbenzimidazol (DRB) for 0, 12, and 24 h. The levels of VPAC1 mRNA expression were measured by TaqMan qPCR. After treatment with DRB, the levels of VPAC1 in the cells decreased from 0 to 12 h by about 70%, but were restored after 24 hours. These results support that the hypophosphorylated IK pool is most likely responsible for transcriptional regulation of VPAC1. Overall, DRB downregulates VPAC1 expression by inhibiting the phosphorylation of IK through the inhibition of CKII. Funding: NIH‐K01 1K01DK064828 and COBRE 2P20RR05566.
