Limits...
Differences in Signal Activation by LH and hCG are Mediated by the LH/CG Receptor's Extracellular Hinge Region.

Grzesik P, Kreuchwig A, Rutz C, Furkert J, Wiesner B, Schuelein R, Kleinau G, Gromoll J, Krause G - Front Endocrinol (Lausanne) (2015)

Bottom Line: These helix preserving modifications showed no effect on hormone-induced signaling.This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region.In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the hinge region of the receptor.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institut für Molekulare Pharmakologie (FMP) , Berlin , Germany.

ABSTRACT
The human lutropin (hLH)/choriogonadotropin (hCG) receptor (LHCGR) can be activated by binding two slightly different gonadotropic glycoprotein hormones, choriogonadotropin (CG) - secreted by the placenta, and lutropin (LH) - produced by the pituitary. They induce different signaling profiles at the LHCGR. This cannot be explained by binding to the receptor's leucine-rich-repeat domain (LRRD), as this binding is similar for the two hormones. We therefore speculate that there are previously unknown differences in the hormone/receptor interaction at the extracellular hinge region, which might help to understand functional differences between the two hormones. We have therefore performed a detailed study of the binding and action of LH and CG at the LHCGR hinge region. We focused on a primate-specific additional exon in the hinge region, which is located between LRRD and the serpentine domain. The segment of the hinge region encoded by exon10 was previously reported to be only relevant to hLH signaling, as the exon10-deletion receptor exhibits decreased hLH signaling, but unchanged hCG signaling. We designed an advanced homology model of the hormone/LHCGR complex, followed by experimental characterization of relevant fragments in the hinge region. In addition, we examined predictions of a helical exon10-encoded conformation by block-wise polyalanine (helix supporting) mutations. These helix preserving modifications showed no effect on hormone-induced signaling. However, introduction of a structure-disturbing double-proline mutant LHCGR-Q303P/E305P within the exon10-helix has, in contrast to exon10-deletion, no impact on hLH, but only on hCG signaling. This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region. In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the hinge region of the receptor.

No MeSH data available.


Predicted structural segments for the middle part of the extracellular hinge region of LHCGR. For exon10, and the following residues, there is great sequence similarity to the crystal structural fragment of transferritin, which contains a helix. Four different methods I-TASSER [Cyan in (B)] (30, 31), Robetta [orange in (B)] (32), IntFold [magenta in (B)] (33), and RaptorX [blue in (B)] (34) predicted a common tertiary structure of the middle hinge region resulting in two helix segments, one for the exon10-region [orange cylinders in (A)] and for the following residues [gray cylinders in (A)]. Due to the consistent helix predictions by different methods and with the existing helix structure in homologous fragments, it is likely that this sequence contains a high propensity for an exon10-helix and an adjacent helix. The hormone binding sensitive sulfation site sTyr331 is located in an accessible coiled region.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4585211&req=5

Figure 2: Predicted structural segments for the middle part of the extracellular hinge region of LHCGR. For exon10, and the following residues, there is great sequence similarity to the crystal structural fragment of transferritin, which contains a helix. Four different methods I-TASSER [Cyan in (B)] (30, 31), Robetta [orange in (B)] (32), IntFold [magenta in (B)] (33), and RaptorX [blue in (B)] (34) predicted a common tertiary structure of the middle hinge region resulting in two helix segments, one for the exon10-region [orange cylinders in (A)] and for the following residues [gray cylinders in (A)]. Due to the consistent helix predictions by different methods and with the existing helix structure in homologous fragments, it is likely that this sequence contains a high propensity for an exon10-helix and an adjacent helix. The hormone binding sensitive sulfation site sTyr331 is located in an accessible coiled region.

Mentions: In this context, the naturally occurring deletion in LHCGR of the complete exon10-encoded segment (LHCGR-delExon10), corresponding to 27 amino acids (Figure 2A) within the hinge region of the hLHCGR, could be directly linked to a case of type 2 Leydig cell hypoplasia in which the natural hLH-, but not hCG-induced function was disturbed (8, 9). The resulting dysfunction in sexual puberty could be overcome by medication with hCG, but the observed functional differences in the exon10-deletion mutant have not yet been fully explained at the molecular level.


Differences in Signal Activation by LH and hCG are Mediated by the LH/CG Receptor's Extracellular Hinge Region.

Grzesik P, Kreuchwig A, Rutz C, Furkert J, Wiesner B, Schuelein R, Kleinau G, Gromoll J, Krause G - Front Endocrinol (Lausanne) (2015)

Predicted structural segments for the middle part of the extracellular hinge region of LHCGR. For exon10, and the following residues, there is great sequence similarity to the crystal structural fragment of transferritin, which contains a helix. Four different methods I-TASSER [Cyan in (B)] (30, 31), Robetta [orange in (B)] (32), IntFold [magenta in (B)] (33), and RaptorX [blue in (B)] (34) predicted a common tertiary structure of the middle hinge region resulting in two helix segments, one for the exon10-region [orange cylinders in (A)] and for the following residues [gray cylinders in (A)]. Due to the consistent helix predictions by different methods and with the existing helix structure in homologous fragments, it is likely that this sequence contains a high propensity for an exon10-helix and an adjacent helix. The hormone binding sensitive sulfation site sTyr331 is located in an accessible coiled region.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585211&req=5

Figure 2: Predicted structural segments for the middle part of the extracellular hinge region of LHCGR. For exon10, and the following residues, there is great sequence similarity to the crystal structural fragment of transferritin, which contains a helix. Four different methods I-TASSER [Cyan in (B)] (30, 31), Robetta [orange in (B)] (32), IntFold [magenta in (B)] (33), and RaptorX [blue in (B)] (34) predicted a common tertiary structure of the middle hinge region resulting in two helix segments, one for the exon10-region [orange cylinders in (A)] and for the following residues [gray cylinders in (A)]. Due to the consistent helix predictions by different methods and with the existing helix structure in homologous fragments, it is likely that this sequence contains a high propensity for an exon10-helix and an adjacent helix. The hormone binding sensitive sulfation site sTyr331 is located in an accessible coiled region.
Mentions: In this context, the naturally occurring deletion in LHCGR of the complete exon10-encoded segment (LHCGR-delExon10), corresponding to 27 amino acids (Figure 2A) within the hinge region of the hLHCGR, could be directly linked to a case of type 2 Leydig cell hypoplasia in which the natural hLH-, but not hCG-induced function was disturbed (8, 9). The resulting dysfunction in sexual puberty could be overcome by medication with hCG, but the observed functional differences in the exon10-deletion mutant have not yet been fully explained at the molecular level.

Bottom Line: These helix preserving modifications showed no effect on hormone-induced signaling.This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region.In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the hinge region of the receptor.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institut für Molekulare Pharmakologie (FMP) , Berlin , Germany.

ABSTRACT
The human lutropin (hLH)/choriogonadotropin (hCG) receptor (LHCGR) can be activated by binding two slightly different gonadotropic glycoprotein hormones, choriogonadotropin (CG) - secreted by the placenta, and lutropin (LH) - produced by the pituitary. They induce different signaling profiles at the LHCGR. This cannot be explained by binding to the receptor's leucine-rich-repeat domain (LRRD), as this binding is similar for the two hormones. We therefore speculate that there are previously unknown differences in the hormone/receptor interaction at the extracellular hinge region, which might help to understand functional differences between the two hormones. We have therefore performed a detailed study of the binding and action of LH and CG at the LHCGR hinge region. We focused on a primate-specific additional exon in the hinge region, which is located between LRRD and the serpentine domain. The segment of the hinge region encoded by exon10 was previously reported to be only relevant to hLH signaling, as the exon10-deletion receptor exhibits decreased hLH signaling, but unchanged hCG signaling. We designed an advanced homology model of the hormone/LHCGR complex, followed by experimental characterization of relevant fragments in the hinge region. In addition, we examined predictions of a helical exon10-encoded conformation by block-wise polyalanine (helix supporting) mutations. These helix preserving modifications showed no effect on hormone-induced signaling. However, introduction of a structure-disturbing double-proline mutant LHCGR-Q303P/E305P within the exon10-helix has, in contrast to exon10-deletion, no impact on hLH, but only on hCG signaling. This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region. In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the hinge region of the receptor.

No MeSH data available.