Does histamine contribute to increased RANKL to osteoprotegerin ratio through altered nuclear receptor 4A activity in human chondrocytes?
Our findings indicate that histamine, via H(1)  and H(2)  histamine receptors, contributes to joint disease by enhancing the ratio of RANKL to OPG expression through altered NR4A activity in human chondrocyte cells.
The potency of previously isolated peptides that are modest agonists of the EPO receptor was dramatically increased by PEG-induced dimerization. The EPO receptor is thought to be dimerized during activation, so our results are consistent with the proposed 2:2 receptor : peptide stoichiometry. The conversion of an inactive peptide into an agonist further supports the idea that dimerization can mediate receptor activation.