• 제목/요약/키워드: granulosa cells

검색결과 239건 처리시간 0.026초

한우 난포낭종에서 증가되는 섬유소원 유전자 발현 (Fibrinogen mRNA Expression Up-Regulated in Follicular Cyst of Korean Cattle)

  • 탁현민;한재희;강다원
    • 한국수정란이식학회지
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    • 제25권1호
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    • pp.29-34
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    • 2010
  • 난포낭종은 소 번식 장애의 주요 원인 중의 하나이며, 다양한 유전자의 변화는 여러 세포와 조직 기능에 영향을 준다. 이러한 유전자 변화는 낭종성 난소에서도 나타날 수 있다. 이온 및 수송체와 관련된 유전자 변화가 한우의 난포낭종을 유발할 수 있을 것이라는 가설 하에 난포낭종성 난포에서 발현 변화를 보이는 유전자를 찾기 위하여 마이크로어레이 분석을 수행하였다. 마이크로어레이 분석 결과, 난포낭종성 난포에서 FGG와 LRP8이 증가하고, SLC44A4, SLC27A5, ANXA8 및 aquaporin 4는 감소하였다. 반정량적 역전사중합효소 연쇄 반응으로 마이크로어레이 분석 결과를 재확인하였다. 6개의 DEG 중 3개의 DEG(FGG, SLC44A4 및 aquaporin 4)는 마이크로어레이 분석 결과와 동일하게 증가와 감소를 보였다. 마이크로어레이와 역전사중합효소 반응에서 동일한 결과를 보이는 3개의 유전자 중 가장 크게 변화를 보인 섬유소원에 중점을 두고 연구를 수행하였다. 마이크로어레이와 역전사중합효소 연쇄 반응은 난포낭종성 난포에서 섬유소원 유전자 발현을 각각 8.4배와 1.7배 증가시켰다. 그러나 난포 및 과립층세포에서 섬유소원의 단백질 양은 웨스턴 블랏 분석으로 분석한 결과, 정상에 비하여 낭종에서 유의한 차이를 보이지 않았다. 본 연구에서 섬유소원은 유전자와 단백질 발현에 있어 상관관계는 보이지 않았지만 섬유소원 유전자는 정상 조직으로부터 난포낭종을 구별하는데 있어서 중요한 생물표지자가 될 수 있는 가능성을 제시한다.

체외수정시술을 위한 과배란유도시 Highly Purified Follicle Stimulating Hormone (HP-FSH) 피하주사와 Follicle Stimulating Hormone 근육주사의 비교연구 (Subcutaneous Administration of Highly Purified-FSH(HP-FSH) versus Intramuscular Administration of FSH in Superovulation for IVF-ET)

  • 배상욱;김진영;원종건;정창진;장경환;이병석;박기현;조동제;송찬호
    • Clinical and Experimental Reproductive Medicine
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    • 제24권1호
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    • pp.135-141
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    • 1997
  • The early studies demonstrated that the relative amount of FSH was important for stimulating normal ovarian activity and demonstrated the existence of a threshold level for FSH, above which follicular growth was activated. It was found that only a modest increase in circulating FSH level above the threshold (between 10 and 30%) was required to stimulate folliculogenesis. In addition, FSH is primary responsible for initiating estradiol production through the activation of the aromatase enzyme system in granulosa cells, follicular secretion and growth. LH on the other hand, plays a supportive role in ovarian steroidogenesis, stimulating the ovarian thecal cells to produce androgen, the precursor for estradiol synthesis. But there is now an increasing number of reports in the literature demonstrating an adverse effect of LH on fertility and miscarriage in infertile and fertile women. So HP-FSH is the drug of a highly purified FSH preparation which has a higher specific activity and far fewer impurities than FSH. This study was performed to evaluate the efficacy and safety of HP-FSH administered (SC; subcutaneous) versus FSH(IM; intramuscular) for ovulation induction. 20 candidates patients for ovulation induction were participated. All patients underwent pituitary desensitizing with a long gonadotropin-releasing hormone (GnRH) agonist protocol and ovulation induction was started with HP-FSH SC (10 patients; group I) or FSH IM (10 patients; group II). After ovulation, outcome of ovulation induction and local reaction of injection site were compared. There were no difference of outcome of ovulation in two groups except pregnancy rate/embryo transfer. Group I had a higher pregnancy rate/ embryo transfer than Group II (44.4% Vs 28.6%). Pain, redness, tenderness, bruising and itching when the injection received on the first 5 days of treated (50 SC and 50 IM injections) were assessed. There were no significant difference (P>0.05) in the incidence of tenderness, bruising and itching between the IM and SC injection. But IM injection (FSH) had a tendency of higher above incidence. The number of reports of pain, redness were significantly increased in IM injection group (P<0.05). These results indicate that SC administration of HP-FSH has been shown to be as effect for superovulation as traditional gonadotropins, with an improved safety profile due to the removal of extaneous proteins.

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사람 난자-난구 복합체 ECM의 Gelatinase (Gelatinases of Extracellular Matrix of Human Oocyte-Cumulus Complex)

  • 이인선;나경아;김해권
    • 한국발생생물학회지:발생과생식
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    • 제5권2호
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    • pp.123-129
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    • 2001
  • 포유동물의 난포내 난자의 성숙 시에는 난자를 둘러싸고 있는 난구세포의 확장 현상이 일어나는데 이 현상에는 hyaluronic acid 뿐만 아니라 다른 성분도 관여하는 것으로 알려져 있다. 본 연구는 조직 재구성 과정에서 중요한 역할을 하는 matrix metalloproteinase(MMP)가 사람의 성숙한 난자-난구 복합체의 extracellular matrix(ECM)에 존재하는지의 여부를 알아보고자 하였다. 체외수정 시술 시에 얻어지는 사람의 난자-난구 복합체를 재료로 zymography와 western blotting 방법으로 조사한 결과 난자-난구 복합체의 ECM에는 300kDa, 240kDa, 200kDa, 180kDa, 116kDa, 97kDa, 그리고 84kDa의 분자량을 갖는 적어도 7종류의 gelatinase들이 존재하는 것이 관찰되었다. 이들 gelatinase가 MMP인지를 확인하기 위해 zymography 동안에 ethylenediaminetetraacetic acid 혹은 phenanthroline 등의 MMP 억제제를 처리한 결과 7종류 모두의 gelatinase 효소활성이 사라졌다. 또한 MMP의 활성제인 aminophenylmercuric acetate를 zymography를 시행하기 전에 ECM에 처리한 결과 200kDa, 180kDa, 97kDa, 84kDa의 gelatinase활성이 사라지고, 대신에 80kDa, 65kDa, 60kDa의 분자량을 갖는 새로운 gelatinase 단백질의 효소활성이 나타났다. 이로 미루어 사람 난자-난구 복합체의 ECM에는 여러 종류의 gelatinase들이 있으며 이들 중 일부는 MMP-2와 MMP-9의 동위효소들인 것으로 여겨진다.

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Protective Effect of BOEC Co-Culture System against Nitric Oxide on Development of Bovine IVM/IVF Embryos

  • Jang, Hyun-Yong;Jung, Yu-Sung;Li, Zheng-Yi;Yoon, Hyoung-Jong;Cheong, Hee-Tae;Kim, Jong-Taek;Park, Choon-Keun;Yang, Boo-Keun
    • Reproductive and Developmental Biology
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    • 제32권3호
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    • pp.167-173
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    • 2008
  • Somatic cells such as oviduct epithelial cell, uterine epithelial cell, cumulus-granulosa cell and buffalo rat river cell has been used to establish an effective culture system for bovine embryos produced in in vitro. But nitric oxide (NO) metabolites secreted from somatic cells were largely arrested the development of bovine in vitro matured/ in vitro fertilized (IVM/IVF) embryos, suggesting that NO was induced the embryonic toxic substance into culture medium. The objective of this study was to investigate whether BOEC co-culture system can ameliorate the NO-mediated oxidative stress in the culture of bovine IVM/IVF embryos. Therefore, we evaluated the developmental rate of bovine IVM/IVF embryos under BOEC co-culture system in the presence or absence of sodium nitroprusside (SNP), as a NO donor, and also detected the expression of growth factor (TGF-$\beta$, EGF and IGFBP) and apoptosis (Caspase-3, Bax and Bcl-2) genes. The supplement of SNP over 5 uM was strongly inhibited blastocyst development of bovine IVM/IVF embryos than in control and 1 uM SNP group (Table 2). The developmental rates beyond morulae stages of bovine IVM/IVF embryos co-cultured with BOEC regardless of SNP supplement (40.4% in 5 uM SNP+ BOEC group and 65.1% in BOEC group) were significantly increased than those of control (35.0%) and SNP single treatment group (23.3%, p<0.05: Table 3). The transcripts of Bax and Caspase-3 genes were detected in all experiment groups (1:Isolated fresh cell (IFC), 2:Primary culture cell (PCC), 3:PCC after using the embryo culture, 4: PCC containing 5 uM SNP and 5: PCC containing 5 uM SNP after using the embryo culture), but Bcl-2 gene was not detected in IFC and PCC (Fig. 1). In the expression of growth factor genes, TGF-$\beta$ gene was found in all experimental groups, and EGF and IGFBP genes were not found in IFC and PCC (Fig. 2). These results indicate that BOEC co-culture system can increase the development beyond morula stages of bovine IVM/IVF embryos, possibly suggesting the alleviation of embryonic toxic substance like nitric oxide.

정경탕(定經湯)이 Estradiol Valerate로 유도된 흰쥐의 다낭성 난소에 미치는 영향 (Effects of Jeongkyeong-Tang on the Estradiol Valerate-induced Polycystic Ovary in Rats)

  • 남은정;이동녕;서일복;김형준
    • 대한한방부인과학회지
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    • 제20권1호
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    • pp.99-113
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    • 2007
  • Purpose : This study was designed to investigate the effects of Jeongkyeong-Tang(JKT) on the polycystic ovary(PCO) induced by estradiol valerate(EV) in rats. Methods : PCO was induced by single intramuscular injection with EV(4mg) in female rats. Normal group(n=8) were injected with sesame oil and orally administrated distilled water for sixty days. PCO control group(n=8) were injected with EV and orally administrated distilled water for sixty days. JKT treated group(n=8) were injected with EV and orally administrated JKT for sixty days. Then we measured weights of body, ovaries and adrenal glands, and measured content of serum estrogen. The histomorphometrical changes of ovaries were also evaluated. The expressions of nerve growth factor(NGF) were analyzed in the central nervous system, adrenal glands and ovaries by immunohistochemistry. Results : - The weights(mg) of ovaries in JKT treated group (69.7${\pm}$6.7) were significantly increased( p<0.001) compared with PCO control group(46.7${\pm}$12.2). - The numbers of secondary follicles in JKT treated group(4.00${\pm}$l.31) were significantly increased(p <0.05) compared with PCO control group(2.25${\pm}$1.39). - The numbers of mature follicles in JKT treated group(5.50${\pm}$1.51) were significantly increased(p<0.01) compared with PCO control group(2.88${\pm}$1.13). - The numbers of atretic follicles in JKT treated group(2.75${\pm}$l.16) were significantly decreased(p<0.001) compared with PCO control group(6.88${\pm}$2.03). - The numbers of corpora lutea in JKT treated group(4.13${\pm}$1.46) were significantly increased(p<0.01) compared with PCO control group(2.13${\pm}$1.46). - The contents(pg/ml) of serum estrogen in JKT treated group(115.18${\pm}$18.29) were significantly decreased(P<0.01) compared with PCO control group(153.06${\pm}$29.47). - The expressions of NGF-immunoreactive cells in the ovarian granulosa cells in JKT treated group were lesser observed than PCO control group. Conclusion : From the above results, we concluded that Jeongkyeong-Tang has inhibitory effect on the development of EV-induced polycystic ovary. And it's effect may be related with decreased NGF activities in the ovary.

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한우 체외수정란의 동결보존시 평형시간과 배 발달단계가 생존성에 미치는 영향 (Effect of Equilibration Time and Cell Stage on the Survival of IVF Bovine Embryos Cryopreserved by Vitrification)

  • 공일근;주영국;이은봉;김용권;박충생
    • 한국수정란이식학회지
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    • 제9권1호
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    • pp.7-14
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    • 1994
  • The present experiments on cryopreservation were designed to examine the effects of solution toxicity, equilibration time and cell stages on the post-thaw survival of bovine IVF embryos. The oocytes were matured in vitro(IVM) for 24 hrs. in TCM-199 supplemented with 35 $\mu$g /ml FSH, 10 $\mu$g /ml LH, 1 $\mu$g /ml estradiol-17$\beta$ and granulosa cells at 39$^{\circ}C$ under 5% $CO_2$ in air. They were fertilized in vitro(IVF) by epididymal spermatozoa treated with heparin for 24 hrs., and then the zygotes were co-cultured in vitro(IVC) with bovine oviductal epithelial cells for 7 to 9 days. The bovine IVF embryos were exposed to the EFS solution in one step at room temperature, kept in the EFS solution during different period for toxicity test, vitrified in liquid nitrogen, and thawed rapidly. 1. after the bovine blastocysts were exposed to EFS solution for 2 min. at room temperature and then they were washed in 0.5 M sucrose solution and TCM-199, they were cultured to examined cryoprotectant induced injury during exposure, Most of the embryos(95.0%) developed to reexpanded blastocoels. However, when the exposure time was extended to 5 and 10 min, these development rates dropped dramatically in 5 min. (69.5%) and 10 min. (47.4%), respectively, 2. When the bovine IVF embryos were vitrified in EFS solution after the equilibration for 1 and 2 min. exposure, The embryos to have reexpanded blastocoels following thawing, washing and culture processes were found to he 82.6 and 73.9%, respectively. However, when the exposure time was extended to 3 min, this survival rate dropped to 18.2%. The optimal time for equilibration of bovine IVF blastocysts in EFS solution seemed to he 1~2 min. 3. When the bovine IVF embryos were equilibrated for 1 min. the significantly (P<0. 05) higher post-thaw survival rates were obtained from the embryos of blastocyst stage(81.3%) than morulae stage(5. 1%). The optimal cell stage for viterification with EFS solution proven to he blastocyst stage in bovine IVF embryos. 4. The number of blastomeres of blastocyst stage was examined with nuclear staining with Hoechst 33342 during 7 to 9 days post-insemination. The cell counts of frozen bovine IVF embryos were found significantly(P$\geq$7.5 and those of the fresh embryos 76.6$\geq$7. 1, which were cultured in the sarne period and conditions as frozen embryos.

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귀비탕(歸脾湯)이 Estradiol Valerate로 유도된 흰쥐의 다낭성 난소에 미치는 영향 (Effects of Gwibi-Tang on the Estradiol Valerate-induced Polycystic Ovaries in Rats)

  • 이연경;서일복;이동녕;김형준
    • 대한한방부인과학회지
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    • 제21권3호
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    • pp.60-74
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    • 2008
  • Purpose: This study was designed to investigate the effects of Gwibi-Tang(GBT) on the polycystic ovary(PCO) induced by estradiol valerate(EV) in rats. Methods: PCO was induced by single intramuscular injection with EV(4mg) in female rats. Normal group(n=8) were injected with sesame oil and orally administrated distilled water for eight weeks. PCO control group(n=8) were injected with EV and orally administrated distilled water for eight weeks. GBT treated group(n=8) were injected with EV and orally administrated GBT for eight weeks. Then we measured weight of body, ovaries, adrenal glands, and uterus of rats. The histopathology changes of ovaries were also evaluated. The expression of nerve growth factor(NGF) was analyzed in the central nervous system, adrenal glands and ovaries by immunohistochemistry. And also CRF expression in median eminance of Rats were analyzed. Results: 1. The weight(g) of rats in GBT treated group($275{\pm}14$) was significantly increased(p<0.01) compared with control group($253{\pm}8$), 2. The weight(mg) of ovaries in GBT treated group($75.8{\pm}16.7$) was significantly increased(p<0.001) compared with control group($37.4{\pm}6.7$). 3. The number of mature follicles in GBT treated group($3.6{\pm}1.2$) was significantly increased(p<0.01) compared with control group($1.5{\pm}1.5$. 4. The number of atretic follicles in GBT treated group($8.0{\pm}3.1$) was significantly decreased(p<0.01) compared with control group($18.6{\pm}6.0$). 5. The number of cystic follicles in GBT treated group($0.5{\pm}0.5$) was significantly increased(p<0.01) compared with control group($2.3{\pm}1.3$). 6. The number of corpora lutea in GBT treated group($6.1{\pm}3.9$) was significantly increased(p<0.01) compared with control group($1.6{\pm}2.3$). 7. The expression of NGF-immunoreactive cells in the ovarian granulosa cells in GBT treated group was lesser observed than control group. Conclusion: From the above results, we concluded that Gwibi-Tang has inhibitory effect on the development of EV-induced polycystic ovary. And it's effect may be related with decreased NGF activities in the ovary.

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생쥐 난소 내 Nesfatin-1/NUCB2 발현과 결합 부위 확인 (Expression of Nesfatin-1/NUCB2 and Its Binding Site in Mouse Ovary)

  • 김진희;윤미라;방소영;심지연;강희래;양현원
    • 한국발생생물학회지:발생과생식
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    • 제14권4호
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    • pp.287-295
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    • 2010
  • 최근 시상하부에서 생성되는 nesfatin-1/NUCB2가 섭식과 에너지 대사를 조절한다는 사실이 새롭게 밝혀졌다. 본 연구에서는 이러한 단백질이 생쥐의 생식기관에서도 발현을 하는지, 그리고 그 수용체가 생식기관 내에 존재하는 지를 확인함으로써 nesfatin-1이 생식기능에 미칠 수 있는 가능성을 알아보고자 하였다. 암컷 생쥐에서 난소와 자궁을 획득하여 conventional PCR 방법으로 NUCB2 mRNA 발현을 조사하였고, real-time PCR 방법으로 상대적인 NUCB2 mRNA 발현량을 비교 분석하였다. 난소 내 nesfatin-1 단백질의 발현 위치를 조사하기 위하여 nesfatin-1 항체를 이용한 면역조직화학염색법을 수행하였으며, biotin conjugated nesfatin-1을 이용하여 nesfatin-1 결합 부위를 확인하였다. 또한 생식소 내 NUCB2 mRNA 발현이 성선자극호르몬에 의해 영향을 받는지 알아보기 위해 PMSG 투여 후 NUCB2 mRNA 발현량을 조사하였다. 실험 결과, 생쥐의 난소와 자궁에서 확인된 NUCB2 유전자가 시상하부에서 만큼이나 많은 양이 발현되고 있었다. 면역조직화학적 염색 결과, nesfatin-1 단백질은 협막세포와 대부분의 기질세포에서 발현되었고, 일부 황체세포에서도 발현이 확인되었다. 반면, 난포 내 과립세포에서는 발현되지 않았으나, 특정 난포 내 난자에서는 발현됨을 확인하였다. 한편, nesfatin-1 단백질의 결합 부위는 난소 백막 주위의 기질세포와 협막세포에서 관찰되었다. 또한 PMSG 투여 후 난소와 자궁에서 NUCB2 mRNA의 발현이 유의하게 증가함을 확인하였다. 이상의 결과에서 난소 내 nesfatin-1 단백질의 발현과 그 결합 부위의 존재는 nesfatin-1이 뇌에서 뿐만 아니라 생식기관에서도 국부조절인자로써 중요한 역할을 할 것으로 사료되며, 앞으로 생식기관에 미치는 nesfatin-1의 역할을규명하기위한더많은연구가필요하다고판단된다.

Biological Functions of N- and O-linked Oligosaccharides of Equine Chorionic Gonadotropin and Lutropin/Chorionicgonadotropin Receptor

  • Min, K. S.
    • 한국동물번식학회:학술대회논문집
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    • 한국동물번식학회 2000년도 국제심포지움
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    • pp.10-12
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    • 2000
  • Members of the glycoprotein family, which includes CG, LH, FSH and TSH, comprise two noncovalently linked $\alpha$- and $\beta$-subunits. Equine chorionic gonadotropin (eCG), known as PMSG, has a number of interesting and unique characteristics since it appears to be a single molecule that possesses both LH- and FSH-like activities in other species than the horse. This dual activity of eCG in heterologous species is of fundamental interest to the study of the structure-function relationships of gonadotropins and their receptors. CG and LH $\beta$ genes are different in primates. In horse, however, a single gene encodes both eCG and eLH $\beta$-subunits. The subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$ - and $\beta$ -subunits in the placenta and pituitary. The dual activities of eCG could be separated by removal of the N-linked oligosaccharide on the $\alpha$-subunit Asn 56 or CTP-associated O-linked oligosaccharides. The tethered-eCG was. efficiently secreted and showed similar LH-like activity to the dimeric eCG. Interestingly, the FSH-like activity of the tethered-eCG was increased markedly in comparison with the native and wild type eCG. These results also suggest that this molecular can implay particular models of FSH-like activity not LH-like activity in the eCG/indicate that the constructs of tethered molecule will be useful in the study of mutants that affect subunit association and/or secretion. A single-chain analog can also be constructed to include additional hormone-specific bioactive generating potentially efficacious compounds that have only FSH-like activity. The LH/CG receptor (LH/CGR), a membrane glycoprotein that is present on testicular Leydig cells and ovarian theca, granulosa, luteal, and interstitial cells, plays a pivotal role in the regulation of gonadal development and function in males as well as in nonpregnant and pregnant females. The LH/CGR is a member of the family of G protein-coupled receptors and its structure is predicted to consist of a large extracellular domain connected to a bundle of seven membrane-spanning a-helices. The LH/CGR phosphorylation can be induced with a phorbol ester, but not with a calcium ionophore. The truncated form of LHR also was down-regulated normally in response to hCG stimulation. In contrast, the cell lines expressing LHR-t63I or LHR-628, the two phosphorylation-negative receptor mutant, showed a delay in the early phase of hCG-induced desensitization, a complete loss of PMA-induced desensitization, and an increase in the rate of hCG-induced receptor down-regulation. These results clearly show that residues 632-653 in the C-terminal tail of the LHR are involved in PMA-induced desensitization, hCG-induced desensitization, and hCG-induced down-regulation. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty. Cells expressing LHR-D556Y bind hCG with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation enhances the internalization of the free and agonist-occupied receptors ~2- and ~17-fold, respectively. We conclude that the state of activation of the LHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing LHR-L435R is due to the fast rate of internalization of the bound hCG. This statement is supported by the finding that hCG responsiveness is restored when the cells are lysed and signal transduction is measured in a subcellular fraction (membranes) that cannot internalize the bound hormone.

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Biological Functions of N- and O-linked Oligosaccharides of Equine Chorionic Gonadotropin and Lutropin/Chorionic Gonadotropin Receptor

  • Min, K.S.
    • 한국가축번식학회지
    • /
    • 제24권4호
    • /
    • pp.357-364
    • /
    • 2000
  • Members of the glycoprotein family, which includes CG, LH, FSH and TSH, comprise two noncovalently linked $\alpha$- and $\beta$-subunits. Equine chorionic gonadotropin (eCG), known as PMSG, has a number of interesting and unique characteristics since it appears to be a single molecule that possesses both LH- and FSH-like activities in other species than the horse. This dual activity of eCG in heterologous species is of fundamental interest to the study of the structure-function relationships of gonadotropins and their receptors. CG and LH $\beta$ genes are different in primates. In horse, however, a single gene encodes both eCG and eLH $\beta$ -subunits. The subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$ - and $\beta$-subunits in the placenta and pituitary. The dual activities of eCG could be separated by removal of the N-linked oligosaccharide on the $\alpha$-subunit Asn 56 or CTP-associated O-linked oligosaccharides. The tethered-eCG was efficiently secreted and showed similar LH-like activity to the dimeric eCG. Interestingly, the FSH-like activity of the tethered-eCG was increased markedly in comparison with the native and wild type eCG. These results also suggest that this molecular can implay particular models of FSH-like activity not LH-like activity in the eCG/indicate that the constructs of tethered molecule will be useful in the study of mutants that affect subunit association and/or secretion. A single-chain analog can also be constructed to include additional hormone-specific bioactive generating potentially efficacious compounds that have only FSH-like activity. The LH/CG receptor (LH/CGR), a membrane glycoprotein that is present on testicular Leydig cells and ovarian theca, granulosa, luteal, and interstitial cells, plays a pivotal role in the regulation of gonadal development and function in males as well as in nonpregnant and pregnant females. The LH/CGR is a member of the family of G protein-coupled receptors and its structure is predicted to of a large extracellular domain connected to a bundle of seven membrane-spanning a-helices. The LH/CGR phosphorylation can be induced with a phorbol ester, but not with a calcium ionophore. The truncated form of LHR also was down-regulated normally in response to hCG stimulation. In contrast, the cell lines expressing LHR-t631 or LHR-628, the two phosphorylation-negative receptor mutant, showed a delay in the early phase of hCG-induced desensitization, a complete loss of PMA-induced desensitization, and an increase in the rate of hCG-induced receptor down-regulation. These results clearly show that residues 632~653 in the C-terminal tail of the LHR are involved in PMA-induced desensitization, hCG-induced desensitization, and hCG-induced down-regulation. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty. Cells expressing LHR-D556Y bind hCG with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation enhances the internalization of the free and agoinst-occupied receptors ~2- and ~17- fold, respectively. We conclude that the state of activation of the LHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing LHR-L435R is due to the fast rate of internalization of the bound hCG. This statement is supported by the finding that hCG responsiveness is restored when the cells are lysed and signal transduction is measured in a subcellular fraction (membranes) that cannot internalize the bound hormone.

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