CD38 is a multifunctional enzyme expressed in a variety of mammalian tissues, its catalytic activity was involved in a wide range of physiological processes. Based on the reported inhibitor of human CD38 NADase, 33 purine derivatives were designed and synthesized. The biological activity assay showed that compounds 20 and 38 exhibited almost the same extent of inhibitory activities on human CD38 NADase as the lead compound H2. The results also revealed that small substituents at C-6 of purine ring gave no obvious effect on inhibitory activity, but phenylpropionyl moiety at N-2 could affect the binding mode of the compound with CD38. This study provides a reliable basis for future rational design of inhibitors for CD38.
ADP-ribosyl Cyclase 1 ; antagonists & inhibitors ; Enzyme Inhibitors ; chemical synthesis ; chemistry ; Humans ; Purines ; chemical synthesis ; chemistry

ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca2+-mobilizing second messenger, cyclic ADP- ribose (cADPR), from beta-NAD+. A prototype of mammalian ADPR-cyclases is a lymphocyte antigen CD38. Accumulating evidence indicates that ADPR-cyclases other than CD38 are expressed in various cells and organs. In this study, we discovered a small molecule inhibitor of kidney ADPR-cyclase. This compound inhibited kidney ADPR-cyclase activity but not CD38, spleen, heart or brain ADPR-cyclase activity in vitro. Characterization of the compound in a cell-based system revealed that an extracellular calcium-sensing receptor (CaSR)- mediated cADPR production and a later long-lasting increase in intracellular Ca2+ concentration ([Ca2+]i) in mouse mesangial cells were inhibited by the pre-treatment with this compound. In contrast, the compound did not block CD3/TCR-induced cADPR production and the increase of [Ca2+]i in Jurkat T cells, which express CD38 exclusively. The long-lasting Ca2+ signal generated by both receptors was inhibited by pre-treatment with an antagonistic cADPR derivative, 8-Br-cADPR, indicating that the Ca2+ signal is mediated by the ADPR-cyclse metabolite, cADPR. Moreover, among structurally similar compounds tested, the compound inhibited most potently the cADPR production and Ca2+ signal induced by CaSR. These findings provide evidence for existence of a distinct ADPR-cyclase in the kidney and basis for the development of tissue specific inhibitors.
Receptors, Calcium-Sensing/metabolism ; Rats, Sprague-Dawley ; Rats ; Mice ; Kidney/*enzymology ; Humans ; Enzyme Inhibitors/chemistry/*pharmacology ; Cyclic ADP-Ribose/*metabolism ; Cell Line ; *Calcium Signaling ; Azo Compounds/chemistry/*pharmacology ; Animals ; ADP-ribosyl Cyclase/*antagonists & inhibitors/*metabolism

OBJECTIVETo investigate the mechanism of trichostatin A(TSA), a histone deacetylase (HDAC) inhibitor, in inhibiting the activation of CD(4)(+) T cells in mice.

METHODSThe CD(4)(+) T cells isolated from the spleen of C57BL mice were treated with different concentrations of TSA (2, 20, and 200 nmol/L) for 24 h, and CD(3), CD(28) and interleukin-2 (IL-2) mRNA levels were measured with reverse transcription-polymerase chain reaction. The protein expressions of CD(3), CD(28) and IL-2 were measured by fluorescence-activated cell sorting and ELISA analysis. ZAP70 and PI3K protein expression in CD(4)(+) T cells activated by CD(3) and CD(28) monoclonal antibody were analyzed by Western blotting.

RESULTSTSA dose-dependently inhibited the transcription and protein expression of CD28 in CD(4)(+) T cells and reduced the expression of PI3K protein in activated CD(4)(+) T cells, without showing significant effect on the expression of ZAP70. TSA treatment of the cells also resulted in significantly decreased mRNA and protein expressions of IL-2 (P<0.01).

CONCLUSIONTSA can regulate the immunological activity of CD(4)(+) T cells by inducing mRNA and protein expressions of CD(28), which inhibits the activation of the co-stimulatory signal transduction in CD(4)(+) T cells and decreases the secretion of IL-2.

ADP-ribosyl Cyclase 1 ; antagonists & inhibitors ; Animals ; CD4-Positive T-Lymphocytes ; drug effects ; metabolism ; Cell Line ; Female ; Histone Deacetylase Inhibitors ; pharmacology ; Hydroxamic Acids ; pharmacology ; Interleukin-2 ; metabolism ; Lymphocyte Activation ; drug effects ; Mice ; Mice, Inbred C57BL ; Signal Transduction ; drug effects

BACKGROUNDAcute lung injury (ALI) is a common complication of sepsis that is associated with high mortality. Intracellular Ca2+ overload plays an important role in the pathophysiology of sepsis-induced ALI, and cyclic adenosine diphosphate ribose (cADPR) is an important regulator of intracellular Ca2+ mobilization. The cluster of differentiation 38 (CD38)/cADPR pathway has been found to play roles in multiple inflammatory processes but its role in sepsis-induced ALI is still unknown. This study aimed to investigate whether the CD38/cADPR signaling pathway is activated in sepsis-induced ALI and whether blocking cADPR-mediated calcium overload attenuates ALI.

METHODSSeptic rat models were established by cecal ligation and puncture (CLP). Rats were divided into the sham group, the CLP group, and the CLP+ 8-bromo-cyclic adenosine diphosphate ribose (8-Br-cADPR) group. Nicotinamide adenine dinucleotide (NAD+), cADPR, CD38, and intracellular Ca2+ levels in the lung tissues were measured at 6, 12, 24, and 48 h after CLP surgery. Lung histologic injury, tumor necrosis factor (TNF)-μ, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) activities were measured.

RESULTSNAD+, cADPR, CD38, and intracellular Ca2+ levels in the lungs of septic rats increased significantly at 24 h after CLP surgery. Treatment with 8-Br-cADPR, a specific inhibitor of cADPR, significantly reduced intracellular Ca2+ levels (P = 0.007), attenuated lung histological injury (P = 0.023), reduced TNF-μ and MDA levels (P < 0.001 and P = 0.002, respectively) and recovered SOD activity (P = 0.031) in the lungs of septic rats.

CONCLUSIONSThe CD38/cADPR pathway is activated in the lungs of septic rats, and blocking cADPR-mediated calcium overload with 8-Br-cADPR protects against sepsis-induced ALI.

ADP-ribosyl Cyclase 1 ; metabolism ; Acute Lung Injury ; chemically induced ; drug therapy ; Animals ; Calcium ; metabolism ; Cyclic ADP-Ribose ; analogs & derivatives ; antagonists & inhibitors ; metabolism ; therapeutic use ; Male ; Malondialdehyde ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sepsis ; complications ; Superoxide Dismutase ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism