Functional significance of the BBXXB motif reversed present in the cytoplasmic domains of the human follicle-stimulating hormone receptor

Timossi, Carlos; Ortiz-Elizondo, Carmen; Pineda, David; Dias, James A.; Conn, P. Michael; Ulloa‐Aguirre, Alfredo

doi:10.1016/j.mce.2004.06.004

Cited by 36 publications

(47 citation statements)

References 58 publications

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“…Nevertheless, this particular hFSHR mutant exhibited an increased turnover probably due to increased ubiquitination of the altered receptor (Cohen et al, 2003;Timossi et al, 2004). In contrast, mutation of R 552 or R 556 profoundly altered intracellular signaling (Fig.…”

Section: Intracellular Loopmentioning

confidence: 88%

“…The hFSHR Ctail-BXXBB motif appears to be more important for receptor expression than for G protein coupling, as suggested by studies in which the basic residues present in this motif were replaced by alanine (Timossi et al, 2004). Substitution of K 614 reduced both ligand binding (Fig.…”

Section: Carboxyl-terminal Domainmentioning

confidence: 90%

“…4B) without affecting the ligand binding ability (Fig. 4E) or internalization rate of the receptor (Timossi et al, 2004). These latter effects clearly differ from the scenario prevailing in the other glycoprotein receptors since replacement of the basic K 566 in the hLHR or K 621 in the hTSHR (corresponding to R 552 in the hFSHR), had no effect on agonist-provoked cAMP accumulation, whereas substitution of the comparable hFSHR R 556 residue in these receptors led to either partial (in the hLHR) or complete (in the hTSHR) functional impairment (Chazenbalk et al, 1991;Schulz et al, 2000).…”

Section: Intracellular Loopmentioning

confidence: 90%

“…The role of the BXXBB motif present in the juxtamembrane region of the hFSHR on receptor function has been recently analyzed in more detail in our laboratories (Cohen et al, 2003;Timossi et al, 2004). Replacement of the three basic residues by alanine yielded a =62 kDa under glycosylated form of the receptor, which was unable to bind agonist and activate effector (Figs.…”

Section: Intracellular Loopmentioning

confidence: 99%

“…These latter effects clearly differ from the scenario prevailing in the other glycoprotein receptors since replacement of the basic K 566 in the hLHR or K 621 in the hTSHR (corresponding to R 552 in the hFSHR), had no effect on agonist-provoked cAMP accumulation, whereas substitution of the comparable hFSHR R 556 residue in these receptors led to either partial (in the hLHR) or complete (in the hTSHR) functional impairment (Chazenbalk et al, 1991;Schulz et al, 2000). Further, in the human FSH and TSH receptors, simultaneous substitution of all three basic residues completely abolished agonist-stimulated cAMP production and severely impaired intracellular trafficking and membrane expression of the modified receptors (Chazenbalk et al, 1990;Timossi et al, 2004), whereas in the rat LHR (92% homology with the human counterpart in the serpentine region of the receptor) simultaneous replacement of two out of the three cationic residues present in this motif had no functional consequence (Wang et al, 1993). Therefore, the ultimate basic residue of the BXXBB motif in all glycoprotein receptors appears to play a major role in the interaction of the receptor with the G s protein.…”

Section: Intracellular Loopmentioning

confidence: 99%

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Role of the intracellular domains of the human FSH receptor in GαS protein coupling and receptor expression

Ulloa‐Aguirre

Uribe

Zariñán

et al. 2007

Molecular and Cellular Endocrinology

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The human (h) follicle-stimulating hormone receptor (FSHR) belongs to the superfamily of G protein-coupled receptors (GPCRs). This receptor consists of 695 amino acid residues and is preferentially coupled to the G s protein. This receptor is highly conserved among species (overall homology, 85%), with a 25 %-69 % homology drop when compared to the human LH and TSH receptors. Although studies in prototypical rhodopsin/β-adrenergic receptors suggest that multiple domains in the intracellular loops (iL) and the carboxyl-terminus (Ctail) of these receptors contribute to G protein coupling and receptor expression, there is a paucity of structure/function data on the role of these domains in FSHR function. Employing point mutations we have found that several residues present in the iL2 of the hFSHR are important for both coupling the receptor to the G s protein and maintaining the receptor molecule in an inactive conformation. In fact, HEK-293 cells expressing several hFSHR mutants with substitutions at R 450 (central to the highly conserved ERW triplet motif) and T 453 (a potential target for phosphorylation) failed to mediate ligand-provoked G s protein activation but not agonist binding, whereas substitutions at the hydrophobic L 460 (a conserved residue present in all glycoprotein hormone receptors) conferred elevated basal cAMP to the transfected cells. Thus, this particular loop apparently acts as a conformational switch for allowing the receptor to adopt an active conformation upon agonist stimulation. Residues in both ends of the iL3 are important for signal transduction in a number of GPCRs, including the FSHR. We have recently explored the importance of the reversed BBXXB motif (BXXBB; where B represents a basic residue and X a non-basic residue) present in the juxtamembrane region of the hFSHR iL3. A hFSHR mutant with all basic amino acids present in the iL3 BXXBB motif replaced by alanine failed to bind agonist and activate effector, and was expressed as an immature =62 kDA form of the receptor. Individual substitutions of basic residues resulted in mutants that bound agonist normally but failed to activate effector when replaced at R 552 or R 556 . Triple mutations in the same motif located in the NH 2 -end of the Ctail resulted in a complete inability of the receptor to bind agonist and activate effector, whereas individual substitutions resulted in decreased or virtually abolished agonist binding and cAMP accumulation, with both functions correlating with the detected levels of mature (80 kDa) forms of the receptor. Thus, the BXXBB motif at the iL3 of the FSHR is essential for coupling the activated receptor to the G s protein, whereas the same motif in the Ctail is apparently more important for membrane expression. The role of cysteine residues present in the Ctail of the FSHR is an enigma since there are no conserved cysteines amongst LHR, FSHR and TSHR. C 629 and C 655 are conserved in the gonadotropin receptors but not in the TSHR. Alanine replacement of C 627 had no effect on

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Section: Intracellular Loopmentioning

confidence: 88%

Section: Carboxyl-terminal Domainmentioning

confidence: 90%

Section: Intracellular Loopmentioning

confidence: 90%

Section: Intracellular Loopmentioning

confidence: 99%

Section: Intracellular Loopmentioning

confidence: 99%

See 3 more Smart Citations

Role of the intracellular domains of the human FSH receptor in GαS protein coupling and receptor expression

Ulloa‐Aguirre

Uribe

Zariñán

et al. 2007

Molecular and Cellular Endocrinology

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A single‐domain intrabody targeting the follicle‐stimulating hormone receptor impacts FSH‐induced G protein‐dependent signalling

Raynaud,

Jugnarain,

Vaugrente

et al. 2023

FEBS Letters

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Intracellular variable fragments of heavy‐chain antibody from camelids (intra‐VHH) have been successfully used as chaperones to solve the 3D structure of active G protein‐coupled receptors bound to their transducers. However, their effect on signalling has been poorly explored, although they may provide a better understanding of the relationships between receptor conformation and activity. Here, we isolated and characterized iPRC1, the first intra‐VHH recognizing a member of the large glycoprotein hormone receptor family, the follicle‐stimulating hormone receptor (FSHR). This intra‐VHH recognizes the FSHR third intracellular loop and decreases cAMP production in response to FSH, without altering Gαs recruitment. Hence, iPRC1 behaves as an allosteric modulator and provides a new tool to complete structure/activity studies performed thus far on this receptor.

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Intracellular Trafficking of Gonadotropin Receptors in Health and Disease

Ulloa‐Aguirre

Zariñán

Gutiérrez-Sagal

et al. 2017

Targeting Trafficking in Drug Development

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Gonadotropin receptors belong to the highly conserved subfamily of the G protein-coupled receptor (GPCR) superfamily, the so-called Rhodopsin-like family (class A), which is the largest class of GPCRs and currently a major drug target. Both the follicle-stimulating hormone receptor (FSHR) and the luteinizing hormone/chorionic gonadotropin hormone receptor (LHCGR) are mainly located in the gonads where they play key functions associated to essential reproductive functions. As any other protein, gonadotropin receptors must be properly folded into a mature tertiary conformation compatible with quaternary assembly and endoplasmic reticulum export to the cell surface plasma membrane. Several primary and secondary structural features, including presence of particular amino acid residues and short motifs and in addition, posttranslational modifications, regulate intracellular trafficking of gonadotropin receptors to the plasma membrane as well as internalization and recycling of the receptor back to the cell surface after activation by agonist. Inactivating mutations of gonadotropin receptors may derive from receptor misfolding and lead to absent or reduced plasma membrane expression of the altered receptor, thereby manifesting an array of phenotypical abnormalities mostly characterized by reproductive failure and/or abnormal or absence of development of secondary sex characteristics. In this chapter we review the structural requirements necessary for intracellular trafficking of the gonadotropin receptors, and describe how mutations in these receptors may lead to receptor misfolding and disease in humans.

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Functional significance of the BBXXB motif reversed present in the cytoplasmic domains of the human follicle-stimulating hormone receptor

Cited by 36 publications

References 58 publications

Role of the intracellular domains of the human FSH receptor in GαS protein coupling and receptor expression

Role of the intracellular domains of the human FSH receptor in GαS protein coupling and receptor expression

A single‐domain intrabody targeting the follicle‐stimulating hormone receptor impacts FSH‐induced G protein‐dependent signalling

Intracellular Trafficking of Gonadotropin Receptors in Health and Disease

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