Hamster Melatonin Receptors: Cloning and Binding Characterization of MT1 and Attempt to Clone MT2

Abstract

For many years, it was of interest to identify the sequences encoding the two melatonin receptors (MT1 and MT2) from various species. After publishing the basic molecular characterization of the human, rat, mouse, sheep, and platypus MT1, MT2, or Mel1c receptors, we began cloning the genes from other animals, such as birds, bats, and vipers. The goal was to advance the receptor crystallization, which could greatly contribute the understanding of the sequence/stability relationship. European hamster MT1 receptor was cloned for the first time from this gender, was expressed in stable form in cells, and its binding characterized with a sample of 19 melatonin ligands. Siberian hamster (Phodopus sungorus) expresses a non-functional MT2. We observed that unlike this hamster, the European hamster (Cricetus cricetus) does not have a stop codon in the MT2 sequence. Thus, we undertook the tedious task of cloning the MT2 receptor. We partially succeeded, sequencing the complete exon 2 and a fragment of exon 1 (from putative amino acids 12 to 38 and 77 to 323), after several years of efforts. In order to show that the protein parts we cloned were capable to sustain some binding capacities, we designed a chimeric MT2 receptor using a consensus sequence to replace the unknown amino acids, based on other small rodent MT2 sequences. This chimeric construct could bind melatonin in the nanomolar range. This work is meant to be the basis for attempts from other laboratories of the community to determine the complete natural sequence of the European hamster MT2 receptor. The present work is the first to show that, among the hamsters, if the Siberian is a natural knockout for MT2, the European one is not.

Is There Sufficient Evidence that the Melatonin Binding SiteMT3Is Quinone Reductase 2?

“…This group further showed that Syrian hamsters were a natural knockout organism for this MT 2 receptor subtype (Weaver et al, 1996). Our group recently confirmed the pharmacologic characteristics of the hamster MT 1 receptor, as well as the difficulty of obtaining the MT 2 receptor from European hamsters (Gautier et al, 2018a), although it is probably not knocked out in this subspecies of hamster.…”

A Putative New Melatonin Binding Site in Sheep Brain,MTx: Preliminary Observations and Characteristics

“…To compare these data with those from oMT 1 and oMT 2 , we investigated the behavior of 16 other compounds (Fig. 1) coming from the standard characterization of our cloned MLT receptors as reported in recent years for human (Audinot et al, 2003), rat (Audinot et al, 2008), mouse (Devavry et al, 2012), sheep (Cog e et al, 2009 and hamster MLT receptors (Gautier et al, 2018) as well as some compounds from the general safety pharmacology profile. Under our experimental protocol, only MCA-NAT, 5-HT, Ket, DOI, DA, and NA did not compete with the tracer (n = 2 for pars tuberalis membranes and n = 4 for hypothalamus membranes).…”

Industrial and academic approaches to the search for alternative melatonin receptor ligands: An historical survey

“…In these circumstances, it was obviously the human genes. But the foreseen use of various animal models such as rat, 39 hamster 40 and mice, 41 as well as sheep, 42,43 as a diurnal animal model, was necessary to assess the effect of new ligands on stress and depression. 44 If in some cases, the cloning of those genes was already reported, their pharmacological profiles were poorly described using a large panel of molecules.…”