Dataset Information

A peptide mimic of an antigenic loop of alpha-human chorionic gonadotropin hormone: solution structure and interaction with a llama V(HH) domain.

ABSTRACT: The X-ray structure of a ternary complex between human chorionic gonadotropin hormone (hCG) and two Fvs recognizing its alpha and beta subunits has been recently determined. The Fvs recognize the elongated hCG molecule by its two ends, one being the Leu-12-Cys-29 loop of the alpha subunit. We have designed and synthesized a 17-amino-acid peptide (named PepH14) derived from the sequence of this antigenic loop with the purpose of mimicking its three-dimensional structure and its affinity for antibodies. We have determined the solution structure of PepH14 by homonuclear NMR spectroscopy and derived distance restraints. Comparison of this structure with that of the corresponding antigenic loop of alpha-hCG reveals strong conformational similarities. In particular, the two pairs of residues that establish crucial contacts with the Fv fragment share the same conformation in PepH14 and in the authentic hormone loop. We propose a three-dimensional model of interaction of PepH14 with a llama V(HH) (V(HH)-H14) fragment cloned from a single-chain llama immunoglobulin raised against alpha-hCG. This model has been constrained by the chemical shift variations of the H14 1HN and 15N resonances monitored upon binding with PepH14. Mapping of the backbone chemical shift variations on the V(HH) structure determined by NMR indicates that PepH14 binds to V(HH)-H14 and forms a complex using the three complementary determining regions (CDRs). They define a shallow groove encompassing residues Thr-31, Ala-56, Tyr-59 and Trp-104 which have been shown to be in conformational exchange [Renisio, Pérez, Czisch, Guenneugues, Bornet, Frenken, Cambillau and Darbon (2002) Proteins 47, 546-555] and also Phe-37 and Ala-50. This groove is close to the hydrophobic interface area observed between VH and VL domains in Fvs from classical antibodies, which explains the rather lateral binding of PepH14 on the V(HH).

SUBMITTER: Ferrat G

PROVIDER: S-EPMC1222782 | biostudies-other | 2002 Sep

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:BackgroundCompared to adult studies, studies which involve the treatment of pediatric congenital hypogonadotropic hypogonadism (CHH) are limited and no universal treatment regimen is available. The aim of this study was to evaluate the feasibility of human chorionic gonadotropin (hCG)/human menopausal gonadotropin (hMG) therapy for treating male adolescents with CHH.MethodsMale adolescent CHH patients were treated with hCG/hMG (n = 20) or a gonadotropin-releasing hormone (GnRH) pump (n = 21). The treatment was divided into a study phase (0-3 months) and a follow-up phase (3-12 months). The testicular volume (TV), penile length (PL), penis diameter (PD), and sex hormone levels were compared between the two groups. The TV and other indicators between the groups were analyzed using a t-test (equal variance) or a rank sum test (unequal variance).ResultsBefore treatment, there was no statistical difference between the two groups in terms of the biochemistry, hormones, and other demographic indicators. After 3 months of treatment, the TV of the hCG/hMG and GnRH groups increased to 5.1 ± 2.3 mL and 4.1 ± 1.8 mL, respectively; however, the difference was not statistically significant (P > 0.05, t = 1.394). The PL reached 6.9 ± 1.8 cm and 5.1 ± 1.6 cm (P < 0.05, t = 3.083), the PD reached 2.4 ± 0.5 cm and 2.0 ± 0.6 cm (P < 0.05, t = 2.224), respectively, in the two groups. At the end of 6 months of treatment, biomarkers were in normal range in the two groups. Compared with the GnRH group, the testosterone (T) level and growth of PL and PD were significantly greater in the hCG/hMG group (all P < 0.05). While the TV of both groups increased, the difference was not statistically significant (P > 0.05, t = 0.314). After 9 to 12 months of treatment, the T level was higher in the hCG/hMG group. Other parameters did not exhibit a statistical difference.ConclusionsThe hCG/hMG regimen is feasible and effective for treating male adolescents with CHH. The initial 3 months of treatment may be a window to optimally observe the strongest effects of therapy. Furthermore, results from the extended time-period showed positive outcomes at the 1-year mark; however, the long-term effectiveness, strengths, and weaknesses of the hCG/hMG regimen require further research.Trial registrationClinicalTrials.gov, NCT02880280; https://clinicaltrials.gov/ct2/show/NCT02880280.

Project description:Immunopathological outcomes in Systemic Lupus Erythematosus (SLE; or lupus) are believed to be autoantibody-mediated. Conditions which promote a Th2 skew (such as pregnancy) should encourage antibody production, worsening antibody-mediated diseases while ameliorating Th1/Th17-mediated diseases. Although an increased propensity toward autoreactivity can be observed in pregnant lupus patients and in pregnant lupus-prone mice, whether a unique human pregnancy-specific factor can contribute to such effects is unknown. This study assessed whether human chorionic gonadotropin (hCG, a pregnancy-specific hormone of diverse function) at physiological concentrations could mediate stimulatory influences on immune parameters in non-pregnant, lupus-prone mice, in light of the hormone's ameliorating effects on Th1-mediated autoimmunity in murine models. Results demonstrate that administration of hCG heightened global autoreactivity in such mice; antibodies to dsDNA, RNP68, Protein S, Protein C, β2-glycoprotein 1, and several phospholipids were enhanced, and hormone administration had adverse effects on animal survival. Specifically in splenic cell cultures containing cells derived from lupus-prone mice, hCG demonstrated synergistic effects with TLR ligands (up-modulation of costimulatory markers on B cells) as well as with TCR stimuli (enhanced proliferative responses, enhanced levels of cytokines, and the phosphorylation of p38). In both instances, enhanced synthesis of lupus-associated cytokines was observed, in addition to the heightened generation of autoantibodies reactive toward apoptotic blebs. These results suggest that selective transducive, proliferative, and differentiative effects of hCG on adaptive immune cells may drive autoreactive responses in a lupus environment, and may also potentially provide insights into the association between the presence of higher hCG levels (or the administration of hCG) with the presence (or appearance) of humoral autoimmunity.

Dataset Information

A peptide mimic of an antigenic loop of alpha-human chorionic gonadotropin hormone: solution structure and interaction with a llama V(HH) domain.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets