[Research and application of the SARS-CoV-2 vaccine based on adenovirus vector technology platform].

During the global efforts to prevent and control the COVID-19 pandemic, extensive research and development of SARS-CoV-2 vaccines using various technical approaches have taken place. Among these, vaccines based on adenovirus vector have gained substantial knowledge and experience in effectively combating potential emerging infectious diseases, while also providing novel ideas and methodologies for vaccine research and development (R&D). This comprehensive review focuses on the adenovirus vector technology platform in vaccine R&D, emphasizing the importance of mucosal immunity induced by adenoviral vector-based vaccine for COVID-19 prevention. Furthermore, it analyzes the key technical challenges and obstacles encountered in the development of vaccines based on the adenovirus vector technology platform, with the aim of providing valuable insights and references for researchers and professionals in related fields.

[Investigation and analysis on knowledge, attitude and behavior about adult vaccination of the residents in Shandong Province].

Objective: To understand the knowledge, attitude and behavior of adult residents on influenza, pneumococcus, human papillomavirus (HPV), herpes zoster (HZ), COVID-19, hepatitis B and rabies vaccination in Shandong Province. Methods: From August to September 2022, a multi-stage stratified random sampling method was used to investigate community-dwelling residents aged 18 years old and above in 12 counties (cities and districts) of Shandong Province. A questionnaire survey was used to collect the basic information of the respondents, such as knowledge, attitude and vaccination behavior of influenza, pneumococcus, HPV, HZ, COVID-19, hepatitis B and rabies vaccine. Analysis of variance was used to compare the differences in the respondents' knowledge and attitude scores of different vaccines. The Chi-square test was conducted to compare the differences in vaccination reasons among different characteristics, and a logistic regression model was used to analyze the influencing factors of vaccination behavior. Results: The median age (Q1, Q3) of the 2 754 respondents was 39 (29, 57) years ranging from 18 to 94 years, with a number of 1 234 (44.81%) males. The average score of the respondents' understanding of various knowledge about adult vaccines was less than 4 points, with the highest score for understanding which diseases can be prevented by adult vaccines. The average score of consent and necessity for adult vaccines to prevent diseases was greater than 3.6 points. In terms of knowledge demand and trust in information channels, there was a high level of trust in the recommendations of vaccination outpatient staff and clinical doctors [with scores of (4.15±0.79) and (4.02±0.80), respectively]. The highest demand for information on vaccination safety knowledge was (4.18±0.84) points. In recent two years, 52.11% of the population had been vaccinated with other vaccines in addition to the COVID-19 vaccine and rabies vaccine, and 45.44% of the population felt it was necessary to be vaccinated through media publicity. Women, age growth, high education level, and high-income level were the promoting factors for adopting vaccination behavior. Conclusion: Adult residents in Shandong Province have a basic understanding and supportive attitude towards vaccination, but the vaccination behavior rate is still relatively low, with significant differences in sex, age, education level, and income level. It is necessary to further increase efforts in the breadth and depth of adult vaccination promotion and education, as well as promotion strategies targeting different populations.

[Kindlin-2 regulates endometrium development via mTOR and Hippo signaling pathways in mice].

OBJECTIVE: To investigate the effects and mechanisms of Kindlin-2 on uterus development and reproductive capacity in female mice. METHODS: Cdh16-Cre tool mice and Kindlin-2flox/flox mice were used to construct the mouse model of uterus specific knockout of Kindlin-2, and the effects of Kindlin-2 deletion on uterine development and reproduction capacity of female mice were observed. High expression and knockdown of Kindlin-2 in endometrial cancer cell lines HEC-1 and Ish were used to detect the regulation of mammalian target of rapamycin (mTOR) signaling pathway. In addition, uterine proteins of the female mice with specific knockout of Kindlin-2 and female mice in the control group were extracted to detect the protein levels of key molecules of mTOR signaling pathway and Hippo signaling pathway. RESULTS: The mouse model of uterine specific knockout of Kindlin-2 was successfully constructed. The knockout efficiency of Kindlin-2 in mouse uterus was identified and verified by mouse tail polymerase chain reaction (PCR), Western blot protein identification, immunohistochemical staining (IHC) and other methods. Compared with the control group, the female mice with uterus specific deletion of Kindlin-2 lost weight, seriously impaired reproductive ability, and the number of newborn mice decreased, but the proportion of the female mice and male mice in the newborn mice did not change. Hematoxylin eosin staining (HE) experiment showed that the endometrium of Kindlin-2 knockout group was incomplete and the thickness of uterine wall became thinner. In terms of mechanism, the deletion of Kindlin-2 in endo-metrial cancer cell lines HEC-1 and Ish could downregulate the protein levels of mTOR, phosphorylated mTOR, adenosine monophosphate-activated protein kinase (AMPK), phosphorylated AMPK and phosphorylated ribosomal protein S6 (S6), and the mTOR signal pathway was inhibited. It was found that the specific deletion of Kindlin-2 could upregulate the protein levels of Mps one binding 1 (MOB1) and phosphorylated Yes-associated protein (YAP) in the uterus of the female mice, and the Hippo signal pathway was activated. CONCLUSION: Kindlin-2 inhibits the development of uterus by inhibiting mTOR signal pathway and activating Hippo signal pathway, thereby inhibiting the fertility of female mice.

[Efficacy and safety of venetoclax combined with azacitidine versus CAG regimen combined with decitabine in elderly patients with relapsed acute myeloid leukemia].

Objective: To compare the efficacy and safety of venetoclax (VEN) combined with azacitidine (AZA) versus CAG regimen combined with decitabine (DAC) in elderly patients with relapsed acute myeloid leukemia (AML). Methods: From January 2018 to August 2020, the clinical data of forty-five elderly patients with relapse AML at the First Affiliated Hospital of Soochow University were retrospectively analyzed, including 31 males and 14 females. The median age was 66 (60-80) years old. Eighteen patients were administrated with VEN and AZA, while the other 27 were in CAG with DAC. The complete remission (CR) rate, partial remission (PR) rate, total remission rate (ORR), adverse events and overall survival (OS) were compared between the two groups. Results: At the end of the treatment, the ORR in VEN with AZA group was 77.8% (14/18); including 11 CR and 3 PR. In CAG with DAC group, the ORR was 37.0% (10/27); including 8 CR and 2 PR (P=0.007). Subgroup analysis suggested that VEN with AZA had a higher ORR in patients stratified as intermediate and poor-risk (P=0.013) or with DNA methylation mutations (P=0.007). Main adverse events in both groups were bone marrow suppression, infections, nausea and vomiting, anorexia and fatigue. Grade Ⅲ-Ⅳ cytopenia developed in lower incidence of VEN with AZA group, such as leukopenia (66.7% vs. 100%, P=0.002), anemia (50.0% vs. 92.6%, P=0.002), thrombocytopenia (72.2% vs. 96.3%, P=0.031) and neutropenia (61.1% vs. 92.6%, P=0.014). In addition, less grade Ⅲ-Ⅳ infections occurred in VEN with AZA group (66.7% vs. 33.3%, P=0.028), as well as grade Ⅲ-Ⅳ gastrointestinal events (40.7% vs. 11.1%, P=0.032), grade Ⅲ-Ⅳ fatigue (55.6% vs.11.1%, P=0.003) compared with CAG with DAC group. The 1-year OS in VEN with AZA group versus CAG with DAC group was 42.9% and 31.6% respectively (P=0.150). Conclusion: VEN combined with AZA proves favorable efficacy and tolerablity in elderly patients with relapsed AML.

Phosphatase and tensin homolog (PTEN) suppresses triacylglycerol accumulation and monounsaturated fatty acid synthesis in goat mammary epithelial cells.

Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor in nonruminants and regulates various cellular processes including growth through dephosphorylation of phosphoinositide substrates. Although studies with bovine mammary tissue suggested a role for PTEN during lactation, its potential role in lipid metabolism remains unknown. Objectives of the present study were to determine PTEN abundance in goat mammary tissue at 2 stages of lactation (n = 6 Xinong Saanen dairy goats per stage), and to use gene-silencing and adenoviral transfections in vitro with isolated goat mammary epithelial cells (GMEC) to evaluate the role of PTEN abundance of lipid metabolism-related genes. Abundance of PTEN decreased by 51.5% at peak lactation compared with the dry period. The PTEN was overexpressed in isolated GMEC through adenoviral transfection using an adenovirus system with Ad-GFP (recombinant adenovirus of green fluorescent protein) as control, and silenced via targeted small interfering RNA (siRNA) transfection with a scrambled small interfering RNA as a negative control. Cell culture was performed for 48 h before RNA extraction, triacylglycerol (TAG) analysis, and fatty acid analysis. Overexpression of PTEN downregulated abundance of acetyl-coenzyme A carboxylase α (ACACA), fatty acid synthase (FASN), sterol regulatory element binding transcription factor1 (SREBF1), stearoyl-coenzyme A desaturase 1 (SCD1), diacylglycerol acytransferase 1 (DGAT1), 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6) coupled with an increase in patatin-like-phospholipase domain containing 2 (PNPLA2), hormone-sensitive lipase (LIPE), and carnitine palmitoyltransferase 1 ß (CPT1B). Furthermore, overexpressing PTEN in vitro resulted in a significant decrease in TAG concentration and concentration of C16:1. In contrast, interference of PTEN led to an opposite effect on lipid metabolism in GMEC. These changes suggested a shift from lipogenesis and esterification to lipolysis and fatty acid oxidation. Collectively, PTEN seems to play a role in monounsaturated fatty acids synthesis and lipid accumulation in GMEC.

Correlations of degree of coronary artery stenosis with blood lipid, CRP, Hcy, GGT, SCD36 and fibrinogen levels in elderly patients with coronary heart disease.

OBJECTIVE: To explore the correlations between the degree of coronary artery stenosis with blood lipid, C-reactive protein (CRP), homocysteine (Hcy), gamma-glutamyl transpeptidase (GGT), soluble cluster determinant 36 (sCD36), and fibrinogen (Fib) levels in elderly patients with coronary heart disease. PATIENTS AND METHODS: The Gensini scores for the coronary artery stenosis were analyzed in patients with single-vessel, double-vessel, and multi-vessel coronary artery diseases in observation group and normal people in control group. Changes in blood lipid-associated parameters, including total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), CRP, Hcy, GGT, sCD36, and Fib were compared between the two groups. The correlations between the Gensini score with changes of the blood-associated parameters, CRP, Hcy, GGT, sCD36, and Fib were analyzed. Finally, univariate and multivariate logistic regression analyses were conducted to determine the risk factors for coronary artery stenosis in elderly patients with coronary heart disease. RESULTS: The Gensini score was significantly higher in coronary heart disease patients with multi-vessel, double-vessel, and single-vessel coronary artery diseases compared with that in normal people (p<0.05). The levels of the blood lipid-associated parameters TC, TG, and LDL-C in observation group were substantially higher than those in control group (p<0.05), and the level of HDL-C was notably lower than that in control group (p<0.05). Subjects in observation group had markedly higher levels of CRP, Hcy, GGT, sCD36, and Fib than control group (p<0.05). The Gensini score for the degree of coronary artery stenosis was positively correlated with the levels of the blood lipid-associated parameters TC and TG, CRP, Hcy, GGT, sCD36, and Fib (p<0.05) and negatively associated with the level of HDL-C (p<0.05). Blood lipid-associated parameters, CRP, Hcy, GGT, sCD36, and Fib were the independent risk factors for coronary artery stenosis in elderly patients with coronary heart disease patients. CONCLUSIONS: The elevations of blood lipid, CRP, Hcy, GGT, sCD36, and Fib levels are closely associated with coronary artery stenosis, and serve as the independent risk factors for coronary artery stenosis.

The role of ultrasonography in the diagnosis of persistent sciatic artery.

AIM: To investigate the accuracy of ultrasonography in the diagnosis of persistent sciatic artery (PSA) compared to computed tomography angiography (CTA). MATERIALS AND METHODS: From May 2002 to Dec 2018, 61 consecutive patients seen at Shandong Medical Imaging Research Institute with a clinical suspicion of PSA were included. Ultrasonography was used to assess the abdominal and lower-limb arteries. The main sonographic criteria for a positive diagnosis were the visualisation of PSA, the enlarged internal iliac artery, and abnormality of common femoral artery and superficial femoral artery. These data were compared with CTA findings. Kappa statistics was applied to determine the level of agreement. The sensitivity, specificity, positive and negative predictive values, accuracy, and Youden index of ultrasonography as a diagnostic method were assessed. RESULTS: Ultrasonography findings were positive in 16 of 61 patients with a clinical suspicion of PSA. The diagnosis was confirmed by CTA in 17 patients. There was one false-positive result and two false-negative results at ultrasonography. The kappa value was 0.875. The sensitivity, specificity, positive and negative predictive values, accuracy, and Youden index of ultrasonography were 88.2%, 97.7%, 93.8%, 95.6%, 95.1% and 0.859, respectively. CONCLUSIONS: Ultrasonography could be a reliable, accurate, and non-invasive diagnostic imaging method in the diagnosis of patients with suspected PSA.

Effects of trastuzumab and lapatinib on HER2 positive breast cancer treatment.

This study aimed to evaluate the clinical efficacy of trastuzumab combined with lapatinib in the treatment of human epidermal growth factor receptor 2 (HER2) positive breast cancer. One hundred and fifty-four patients with breast cancer were randomly divided into a trastuzumab group (group A, 52 cases), a lapatinib group (group B, 48 cases) and a combination group (group C, 54 cases).

[Survey of Anopheles vectors in Nanyang City from 2005 to 2017].

OBJECTIVE: To investigate the malaria vectors in Nanyang City. METHODS: Two townships were selected as malaria vector surveillance sites in Nanyang City from 2005 to 2017, including Mazhenfu Township in Tanghe County and Huaiyuan Township in Tongbai County, and the malaria vectors were investigated using the semi-overnight human baiting trapping method and mosquito trapping in nets. RESULTS: The mean density of Anopheles sinensis was 0.65 to 22.30 mosquitos/(person · hour) in the two surveillance sites in Nanyang City using the human baiting trapping method from 2005 to 2017, and the peak density was detected in June and July. An. anthropophagus was captured only in Tongbai County during the period between 2008 and 2011, with a mean density of 0.03 to 1.10 mosquitos/(person · hour). The mean density of An. sinensis was 0.08 to 0.24 mosquitos/(net · night) using the mosquito trapping in nets from 2005 to 2011, and the peak density was detected in July and August, while few An. anthropophagus captured only in Tongbai County, with a mean density of 0.01 to 0.02 mosquitos/(net · night). CONCLUSIONS: There are malaria vectors in Nanyang City, including An. sinensis and An. anthropophagus, and An. sinensis is the dominant mosquito species.

[Clinical features and curative effect analysis of patients with myeloid neoplasms and RUNX1 mutations].

Objective: To investigate the survival and prognostic factors of allogeneic hematopoietic stem-cell transplantation (allo-HSCT) for patients with myeloid neoplasms and RUNX1 mutations. Methods: From July 2014 to April 2018, the clinical data of forty-two AML/MDS patients with RUNX1 mutations in the First Affiliated Hospital of Soochow University were retrospectively analyzed. The clinical characteristic features and distribution of the mutations frequently observed with RUNX1 mutations were summarized, the prognosis of allo-HSCT for these patients was also analyzed. Results: Among 42 AML/MDS patients with RUNX1 mutations, 27 were male, 15 were female. The median age was 43.5 (16-68) years old. There are 31 patients in allo-HSCT group and 11 patients in chemotherapy group. RUNX1 mutations co-occurred with many other gene mutations, the most frequent mutations were FLT3 (26.2%, 11/42) . Interestingly, FLT3 mutations only occurred in AML patients compared with MDS patients (P=0.014) . ASXL1 (25%, 3/12) mutations were observed as the most frequent co-mutations in MDS patients. One-year overall survival (OS) , disease-free survival (DFS) of allo-HSCT and chemotherapy patients were (70.6±9.0) %, (61.0±9.4) % and (34.4±16.7) %, (22.4±15.3) %, respectively. When OS and DFS between allo-HSCT and chemotherapy patients were compared, significant differences (χ(2)=4.843, 4.320, P<0.05) were showed. In univariate analysis, transplant age >45 years was a negative effect for OS [HR=4.819 (95% CI 1.145-20.283) , P=0.032] and DFS [HR=5.945 (95% CI 1.715-20.604) , P=0.005]. Also, complex chromosome karyotype abnormality was a negative effect for OS [HR=5.572 (95%CI 1.104-28.113) , P=0.038]. Conclusion: Transplant age (>45 years) and complex chromosome karyotype abnormality were negative prognostic factors in allo-HSCT for myeloid neoplasms patients with RUNX1 mutations.

Prognostic significance of microRNA-10b overexpression in breast cancer: a meta-analysis.

Many microRNAs (miRNAs) exhibit altered expression levels in cancers, and they may be considered as valuable prognostic biomarkers for cancers. Here we aimed to summarize the recent advances in miR-10b involvement in human breast cancer and analyze the predicting role of miR-10b for survival. We searched, Embase, and Wanfang databases to identify studies on the prognostic role of miR-10b expression in breast cancer. A total of 770 patients from 7 eligible studies were included in the analysis. Pooled risk ratios (RRs) with 95% confidence interval (95%CI) were calculated to estimate the effect. Our results showed that high miR-10b expression in patients with breast cancer was significantly associated with poor disease-free survival (DFS) (RR = 1.53; 95%CI = 1.06-2.21; P = 0.02). However, no significant association between miR-10b and overall survival was found in overall studies. Subgroup analysis indicated that high expression of miR-10b was significantly correlated with DFS in Asia (RR = 2.94; 95%CI = 1.71-5.05). The present meta-analysis demonstrated that high expression of miR-10b might predict poor survival in patients with breast cancer. Larger clinical studies are required to further evaluate the role of miR-10b in clinical practice.

Establishment and characterization of an ovarian cell line from half-smooth tongue sole Cynoglossus semilaevis.

A new ovarian cell line, CSO, was established from half-smooth tongue sole Cynoglossus semilaevis. Primary culture of CSO cells was initiated from digestion of ovarian tissues pieces by trypsin solution and cultured at 24° C in Dulbecco's modified Eagle's medium-F12 medium (DMEM-F12, 1:1) (pH 7·0), supplemented with 20% foetal bovine serum, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I) and human chorionic gonadotropin (HCG). The cultured CSO cells, fibroblastic in morphology, proliferated to 100% confluency 3 days later and had been subcultured to passage 80. Chromosome analyses indicated that the CSO cells exhibited chromosomal aneuploidy with a modal chromosome number of 42 that displayed the normal diploid karyotype of C. semilaevis [2n = 42 t, fundamental number (NF ) = 42]. Reverse transcription polymerase chain reaction revealed that CSO cells could express ovarian somatic cell functional genes p450armo, foxl2 and sox9a but not ovary germ cell marker gene vasa and male-specific gene dmrt1. Transfection experiment demonstrated that CSO cells transfected with pEGFP-N3 plasmid could express green fluorescence protein (GFP) with higher transfection efficiency. The CSO cell line might serve as a valuable tool for studies on the mechanism of sex determination and oogenesis of ovary in flatfish.

Comparative in vitro activities of AC98-6446, a novel semisynthetic glycopeptide derivative of the natural product mannopeptimycin alpha, and other antimicrobial agents against gram-positive clinical isolates.

AC98-6446 is a novel semisynthetic cyclic glycopeptide antibiotic related to the natural product mannopeptimycin alpha (AC98-1). In the present study the activity of AC98-6446 was evaluated against a variety of recent clinical gram-positive pathogens including multiply resistant strains. AC98-6446 demonstrated similar potent activities against methicillin-susceptible and methicillin-resistant staphylococci and glycopeptide-intermediate staphylococcal isolates (MICs at which 90% of isolates are inhibited [MIC(90)s], 0.03 to 0.06 microg/ml). AC98-6446 also demonstrated good activities against both vancomycin-resistant and -susceptible strains of enterococci (MIC(90)s, 0.12 and 0.25 microg/ml, respectively) as well as against streptococcal strains (MIC(90)s, 3 log(10) CFU/ml) of staphylococcal and streptococcal isolates and a marked decrease in the viable counts of most enterococcal strains (from 0.2 to 2.5 log(10) CFU/ml). Unlike vancomycin, which demonstrates time-dependent killing, AC98-6446 demonstrated concentration-dependent killing. The potent activity, novel structure, and bactericidal activity demonstrated by AC98-6446 make it an attractive candidate for further development.

On-line concentration of s-triazine herbicides in micellar electrokinetic chromatography using a cationic surfactant.

On-line concentration of neutral species of s-triazine herbicides in micellar electrokinetic chromatography using tetradecylammonium bromide (TTAB) as a cationic surfactant was investigated. Factors affecting the stacking of analytes were examined. The results indicate that the stacking efficiency is markedly improved with addition of phosphate buffer in the sample matrix. It was found that, depending on the nature of the analytes, the most effective stacking of these analytes occurs when the ratio of the conductivity of buffer electrolyte to that of sample matrix is in the range 1.4-1.2, with sample matrix containing phosphate buffer. Micelle concentration in the separation buffer is also a crucial factor to enhance the stacking efficiency and detection sensitivity of analytes. Moreover, the stacking efficiency of each individual analyte depends on its binding constant to TTAB micelles. The concentration effect is primarily based on sweeping mechanism which is operated in a normal stacking mode with reversed electrode polarity in the presence of reversed electroosmotic flow. As a result of concentration enhancement, the detection limits of these herbicides can reach about 9-15 ng/ml with UV detection.

The discovery of RFI-641 as a potent and selective inhibitor of the respiratory syncytial virus.

The design and synthesis of a new potent and selective inhibitor of the respiratory syncytial virus are described. This compound, RFI-641, emerged from analysis of the structure-activity relationship in a series of biphenyl triazine anionic compounds possessing specific anti-RSV activity. The key synthetic step involves coupling of diaminobiphenyl 11 with two equivalents of chlorotriazine 10 under microwave conditions. RFI-641 inhibited RSV in vitro and in vivo models.

[Studies on chemical constituents in dried buds of Lonicera similis Hemsl].

OBJECTIVE: To study the chemical constituents in the dried buds of Lonicera similis. METHOD: Chromatography and spectral analysis were used to isolate and elucidate the constituents. RESULT: Nine compounds were isolated from the dried buds of L. similis, and identified as caffeic acid; 3,5-O-dicaffeoylquinic acid; chlorogenic acid; palmitic acid; luteolin; quercetin; beta-sitosterol; nonacosanol; nonacosane. CONCLUSION: All the compounds were isolated from the plant for the first time.

Capillary zone electrophoretic separation of neutral species of chloro-s-triazines in the presence of cationic surfactant monomers.

Chloro-s-triazines are difficult to separate by capillary zone electrophoresis (CZE), due to their low pKa values. However, these analytes can be effectively separated by CZE in the presence of cationic surfactant monomers, such as tetradecylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DTAB). The separation mechanism based on a 1:1 binding of analytes to cationic surfactant monomers is proposed. The binding constants of chloro-s-triazines to cationic surfactant monomers are estimated. The results show that the strength of the interactions of these analytes with TTAB monomers is considerably strong, whereas that of the corresponding analyte with DTAB monomers is about 12- to 14-fold weaker. A linear correlation of binding constants with log P(ow) (the logarithm of the partition coefficient of analytes between 1-octanol and aqueous phases) indicates that the migration order of these chloro-s-triazines depends primarily on their hydrophobicity. Moreover, the skewed peaks of chloro-s-triazines observed may reveal the occurrence of adsolubilization of these analytes in the adsorbed cationic surfactant layer on the capillary surface.

Determination of the thermogenesis curves and studies of the thermodynamics and thermokinetics of seed germination.

The thermogenesis curves of the germination of different rice and tree seeds were determined and studied by using a newly constructed microcalorimeter. The thermogenesis curves of the germination of the seeds demonstrate the existence of physiological triphasic patterns, which include imbibition, activation and growth stages in the germination process. The thermodynamics and thermokinetics of the main growth phase of the growth stage in the germination process have been studied. The growth heat effect (deltaH), the growth rate constant (k), the growth inhibitory factor (s) and deceleration rate constant (beta) have been determined and calculated, In addition, the experimental thermokinetic equations of the growth stage in the seed germination process have been established.

Expression of two human skeletal calcitonin receptor isoforms cloned from a giant cell tumor of bone. The first intracellular domain modulates ligand binding and signal transduction.

Two distinct calcitonin (CT) receptor (CTR)-encoding cDNAs (designated GC-2 and GC-10) were cloned and characterized from giant cell tumor of bone (GCT). Both GC-2 and GC-10 differ structurally from the human ovarian cell CTR (o-hCTR) that we cloned previously, but differ from each other only by the presence (GC-10) or absence (GC-2) of a predicted 16-amino acid insert in the putative first intracellular domain. Expression of all three CTR isoforms in COS cells demonstrated that GC-2 has a lower binding affinity for salmon (s) CT (Kd approximately 15 nM) than GC-10 or o-hCTR (Kd approximately 1.5 nM). Maximal stimulatory concentrations of CT resulted in a mean accumulation of cAMP in GC-2 transfected cells that was greater than eight times higher than in cells transfected with GC-10 after normalizing for the number of receptor-expressing cells. The marked difference in maximal cAMP response was also apparent after normalizing for receptor number. GC-2 also demonstrated a more potent ligand-mediated cAMP response compared with GC-10 for both human (h) and sCT (the EC50 values for GC-2 were approximately 0.2 nM for sCT and approximately 2 nM for hCT; EC50 values for GC-10 were approximately 6 nM for sCT and approximately 25 nM for hCT). Reverse transcriptase PCR of GCT RNA indicated that GC-2 transcripts are more abundant than those encoding for GC-10. In situ hybridization on GCT tissue sections demonstrated CTR mRNA expression in osteoclast-like cells. We localized the human CTR gene to chromosome 7 in band q22. The distinct functional characteristics of GC-2 and GC-10, which differ in structure only in the first intracellular domain, indicate that the first intracellular domain of the CTR plays a previously unidentified role in modulating ligand binding and signal transduction via the G protein/adenylate cyclase system.