Luteinizing Hormone Triggers a Molecular Association Between Its Receptor and the Major Histocompatibility Complex Class I Antigen to Produce Cell Activation

Abstract

We studied the involvement of major histocompatibility (MHC) class I antigens on the mechanism of LH/hCG receptor activation. For this purpose we investigated the effects of anti-MHC class I antibodies on hormone-receptor interaction, signal transduction, and MHC class I antigen-receptor interaction. Monoclonal antibodies against MHC class I antigen were able to stimulate testosterone production in mouse Leydig cells with the same potency as LH. This biological effect depends on the concentration of antibody used and could be abolished by a LH antagonist. There is a perfect parallelism, for each monoclonal antibody, between the specificity for a particular haplotype and the response of the target cells from the strains carrying such a haplotype. The same antibodies were able to precipitate the soluble LH/hCG receptors, as both a hormone-receptor complex and a free receptor. The results suggest that bound hormone triggers an association of the MHC class I antigen with the LH/hCG receptor, resulting in activation of the target cell.

Role for β2-Microglobulin in Echovirus Infection of Rhabdomyosarcoma Cells

“…RD cells were incubated with MAb 1350 for 0 to 60 min at 37°C and then chilled on ice (see text). The cells were then incubated with 35 S-radiolabelled virus on ice for 1 h before being washed to remove nonadsorbed virus. The entry of virus into the cells was then stimulated by incubation at 37°C for 5 min, the cells were placed back on ice, and supernatants were removed.…”

“…The cells were then resuspended in 100 l of sDAF (100 g/ml in PBS) for 1 h on ice; sDAF was added in order to remove from the cell surface by competition any virus that had not yet entered the cells or become irreversibly bound into virus-cell complexes (26). The cells were then pelleted, and the 35 S counts in both the supernatant and the cells were determined by scintillation counting.…”

Polygenic Influences on the Length of Oestrous Cycles in Inbred Mice Involve MHC Alleles*

“…Differences among H-2-congenic strains in glucagon-receptor binding affinities (low vs. high) and subsequent adenylate cyclase activation were associated with structural differences in class I glycoproteins. Moreover, luteinizing hormone (LH) receptors are integrally associated with class I glycoproteins (Solano et al, 1988). Haplotype-specific responses were shown using monoclonal antibodies to class I MHC antigens, which influence production of testosterone by Leydig cells in vitro.…”

Proximity measurements between H-2 antigens and the insulin receptor by fluorescence energy transfer: evidence that a close association does not influence insulin binding.

“…Accumulative experimental evidence has supported specific cell-surface associations between MHC class I antigens and various peptide hormone receptors such as interleukin 2 (11), epidermal growth factor (6,31), luteinizing hormone (29), and insulin (5-10, 24, 32). Moreover, through biochemical and genetic studies, it has been suggested that the class I haplotype may determine qualitative and quantitative factors in receptor binding and function (7,24,(32)(33)(34) Although there is close molecular association between cell-surface class I products and the IR, cell lines differing only in their 132m and class I H-2 expression were found identical in IR number and affinity.…”