The C-terminal domains of melanocortin-2 receptor (MC2R) accessory proteins (MRAP1) influence their localization and ACTH-induced cAMP production

详细信息	查看全文 | 推荐本文 |

• 作者：Simon Roy^a ; Sé ; bastien J. Roy^b ; Sandra Pinard^a ; Maria Josep Agulleiro^c ; José ; Miguel Cerdá ; -Reverter^c ; Jean-Luc Parent^b ; Nicole Gallo-Payet^a ; ^{Nicole.Gallo-Payet@USherbrooke.ca}
• 关键词：dCT ; deleted C-terminus ; DPI ; protein disulfide isomerase ; ER ; endoplasmic reticulum ; FRT ; flprecombinase target ; FSK ; forskolin ; a direct activator of adenylyl cyclases ; GPCR ; G protein-coupled receptor ; HEK 293 ; human embryonic kidney ; HRP ; horseradish
• 刊名：General and Comparative Endocrinology
• 出版年：2012
• 期刊代码：169_00166480
• 类别：bio
• 出版时间：1 April, 2012
• 卷：176
• 期：2
• 页码：265-274
• 文件大小：1285 K

摘要

ACTH binding to the human melanocortin-2 receptor (MC2R) requires the presence of the MC2R accessory protein1 isoforms, MRAP伪 or MRAP尾. This study evaluated the role of the isoform-specific C-terminal domains of MRAP with regard to their cellular localization, topology, interaction with MRAP2 and cAMP production. When stably expressed in HEK293/FRT cells or in B16-G4F mouse melanoma cells (an MSH receptor-deficient cell clone), MRAP伪 and MRAPdCT (truncated MRAP1, N-terminal only) localized mainly around the nuclear envelope and within dense intracellular endosomes, while MRAP尾 exhibited a strong localization at the plasma membrane, and partially with rapid recycling endosomes. MRAP尾 and MRAPdCT both exhibited dual-topology (N_cyto/C_exo and N_exo/C_cyto) at the plasma membrane whereas MRAP伪 exhibited only N_cyto/C_exo topology at the plasma membrane while adopting dual-topology in intracellular compartments. Both MRAP伪 and MRAP2 colocalized in intracellular compartments, as opposed to weak colocalization between MRAP尾 and MRAP2. MRAP2 and MC2R enhanced the expression of MRAP1 isoforms and vice versa. Moreover, in both HEK293/FRT and B16-G4F cells, ACTH failed to activate MC2R unless MRAP1 was present. MRAP1 expression enhanced MC2R cell-surface expression as well as concentration-dependent cAMP accumulation. In the presence of human or zebrafish MC2R, MRAP尾 induced the highest cAMP accumulation while MRAPdCT induced the lowest. Together, the present findings indicate that the C-terminal domains of MRAP dictate their intracellular localization in addition to regulating ACTH-induced cAMP production. These preferential localizations suggest that MRAP伪 is involved in MC2R targeting to the plasma membrane, while MRAP尾 may enhance ACTH-MC2R coupling to cAMP production.