Periplakin Interferes with G Protein Activation by the Melanin-concentrating Hormone Receptor-1 by Binding to the Proximal Segment of the Receptor C-terminal Tail

Abstract

The orexigenic cyclic 19 amino acid peptide melanin-concentrating hormone (MCH) 1 (1) is the natural ligand for the G protein-coupled receptor (GPCR) originally designated SLC-1 (also called GPR24 in some studies) because of its relatedness to the receptors for somatostatin (2-6). This polypeptide was thus renamed the MCH-1 receptor. A second MCH receptor (MCH-2 receptor) has also been identified (7-11), and there is some evidence of an MCH binding site that is distinct from these two receptors (12).Even before identification of the MCH receptors a clear role for MCH in feeding and energy balance and homeostasis had been established (1). A solid body of genetic and pharmacological evidence now supports a role for MCH and the MCH-1 receptor in the modulation of food intake and energy expenditure. Key data derive from the genetic ablation of both MCH (13) and the MCH-1 receptor (14, 15) in mice. These alterations produced animals that were both lean and resistant to dietinduced obesity. Mice lacking the MCH-1 receptor have been reported to be hyperphagic (14, 15) but to be both hyperactive and to have altered metabolism, and this may explain the apparent paradox of being resistant to obesity but eating more. Studies also indicate that acute and chronic administration of MCH enhances food intake and body weight (16) and that overexpression of MCH in transgenic mice leads to obesity and insulin resistance (17). A role for the MCH-2 receptor in these effects is unlikely because genetic evidence indicates that mice do not express a functional form of this receptor (18). Furthermore, the distribution of the MCH-1 receptor in the central nervous system (19) also suggests that antagonists at the MCH-1 receptor might provide a treatment for obesity (for review, see Refs. 20 and 21). High throughput screening efforts have led to the identification of small molecule MCH-1 receptor antagonists with diverse structural features and drug-like properties. In vivo results with two of these antagonists indicate efficacy in several animal models of body weight regulation and feeding behavior (21). At least when expressed in

Interaction of Neurochondrin with the Melanin-concentrating Hormone Receptor 1 Interferes with G Protein-coupled Signal Transduction but Not Agonist-mediated Internalization

“…DNA Construction-Generation of a cDNA encoding the C-terminal fragment of the rat MCHR1 (amino acids 299 -353) cloned in pAS2 (BD Biosciences) was described previously (23). cDNAs encoding C-terminal fragments of rat MCHR1-(299 -325), rat MCHR1 (319 -353), human MCHR2-(300 -340), and rat SSTR5-(295-363) were generated by PCR and cloned into yeast bait vector pAS2.…”

“…A rat MCHR1 cDNA fragment (nucleotides 915-1085) was generated by PCR and cloned into the dehydrofolate reductase (DHFR)-HIS vector pQE40 (Qiagen, Hilden, Germany), providing a 30-kDa 6xHIS-DHFR-C-terminal MCHR1 fusion protein, as described (23).…”

“…The construction of a rat MCHR1 cDNA carrying an N-terminal T7 epitope tag was described before (23). C-terminal truncated MCHR1 cDNA encoding rat MCHR1 (amino acids 1-326) was generated by PCR and cloned into pcDNA3, providing an N-terminal T7 epitope tag.…”

“…We have previously used the C-terminal tail of rat MCHR1 as bait in a yeast two-hybrid assay to screen a human brain cDNA library for intracellular interacting proteins. This screen resulted in the identification of both a zinc finger protein termed MCHR1-interacting zinc finger protein (MIZIP) (22) and the actin-and intermediate filament-binding protein periplakin (23). Although the consequences of interactions between the MCHR1 and MIZIP remain to be resolved (22), periplakin inhibits G protein-coupled signal transduction of the MCHR1 (23).…”

Identification of periplakin as a major regulator of lung injury and repair in mice

“…PPL acts as a cytolinker between intermediate filament scaffolding and the desmosomal plaque. In addition, PPL is capable of interacting with other nondesmosomal proteins at the plasma membrane such as AKT (2), Annexin 9 (3), FcγRI (CD64) (4,5), and melanin concentrating hormone receptor 1 (MCHR1) (6) and modulates their signaling pathway. In the lung, PPL is expressed in both lung proximal and distal airway epithelia (7).…”