• 한국발생생물학회지:발생과생식
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• 제10권4호
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• pp.255-261
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• 2006

일부 식물성 에스트로겐(phytoestrogen)의 경우, 긍정적인 효과를 갖는 것으로 보이지만, 대부분의 내분비계 장애 물질(endocrine disruptor 또는 endocrine disrupting compound, EDC)은 노출된 개체의 내분비계를 교란시켜 인간이나 야생 동물의 건강에 해로운 것으로 알려져 있다. 선행 연구에서 본 연구자들은 사춘기 전에 단기간으로 식물성 에스트로겐인 genistein(GS)을 투여했을 때 암컷 흰쥐의 생식계가 활성화되어 조기 사춘기가 유도되지만, 플라스틱 가소제인 di(2-ethyl hexyl)phthalate(DEHP)를 투여했을 때 반대로 생식계의 불활성화가 유도되어 사춘기 지연이 초래됨을 보고하였다. 본 연구에서는 사춘기전 GS 또는 DEHP 투여가 흰쥐 난소와 자궁에서의 성적인 성숙 상태를 반영하는 에스트로겐 수용체($ER\;{\alpha}$ and $ER\;{\beta}$)와 LH 수용체(LHR) 발현에 미치는 효과를 조사하였다. GS(100 mg/kg/day i.p.)를 생후 25일부터 사춘기 개시의 지표인 최초의 질구 개방(vaginal opening, VO)이 일어나는 날까지 투여하고 다음 날(day 32) 희생시켰다. 유사하게, DEHP(100 mg/kg/day i.p.)를 생후 25일부터 대조군(corn oil $200\;{\mu}L$)에서 최초 질구 개방(vaginal opening, VO)이 일어나는 날까지 투여하고 다음 날(day 36) 희생시켰다. 희생 직후 난소와 자궁의 total RNA를 추출하여 각 호르몬 수용체들의 전사 수준을 측정하기 위해 정량적인 RT-PCR을 수행하였다. GS 투여에 의해 자궁에서의 $ER\;{\alpha}$, $ER\;{\beta}$ 그리고 LHR mRNA 수준 모두 대조군에 비해 유의하게 증가하였다. GS군의 난소에서는 LHR 발현이 유의하게 증가하였으나 $ER\;{\alpha}$와 $ER\;{\beta}$의 발현은 증가하는 경향만을 보였다. 한편, DEHP군에서는 난소와 자궁에서의 $ER\;{\alpha}$, $ER\;{\beta}$ 그리고 LHR mRNA 수준은 모두 대조군에 비해 유의하게 감소하였다. 사춘기 전의 암컷 흰쥐의 난소와 자궁에서 성숙과 관련된 생식호르몬 수용체들의 발현 변화는 이들 조직의 무게와 해부학적인 변화, 그리고 혈중 생식호르몬들의 수준 등 사춘기 과정에서의 표현형적인 측면 변화-2차 성징-들을 반영하는 것으로 추정된다.

• Animal cells and systems
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• 제5권1호
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• pp.51-57
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• 2001

We have previously shown that oocyte maturation is induced by an immobilized progesterone, progesterone-3-carboxymethyloxime - bovine serum albumin conjugate (P-BSA) in Rana dybowskii. In this study, we confirmed the maturation inducing activity of P-BSA on Xenopus oocyte and examined the binding character of the immobilized progesterone on the surface of Xenopus oocytes after removal of the vitelline layer. P-BSA induced maturation of Xenopus oocytes but E-BSA failed to do so as observed in Rana. Binding of the immobilized progesterone, fluorescein isothiocyanate-labeled progesterone-3-0-carboxymethyloxime-BSA (P-BSA-FITC) on the devitellined oocytes surface was examined by fluorescence confocal microscopy. The binding affinity of P-BSA-FITC to the devitellined oocyte was higher than that of estrogen-BSA-FITC (E-BSA-FITC) or testosterone-BSA-FITC (T-BSA-FITC). The binding disappeared in the presence of excess free progesterone but not in the presence of free estrogen. Maximum binding occurred after two-hours of incubation with P-BSA-FITC at pH 7.5. Stronger binding occurred in oocytes at stage Vl than stage IV, and in vitro treatment of hCG enhanced the binding. Taken together, these results suggest that a specific receptor for progesterone exists on the plasma membrane of Xenopus oocytes and that progesterone acts initially on this putative receptors and triggers generation of membrane-mediated second messengers during the early stage of oocyte maturation In amphibians.

• 한국발생생물학회지:발생과생식
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• 제25권4호
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• pp.199-211
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• 2021

Equine chorionic gonadotropin (eCG), produced by the endometrial cups of the placenta after the first trimester, is a specific glycoprotein that displays dual luteinizing hormone (LH)-like and follicle-stimulating hormone (FSH)-like effects in non-equid species. However, in equidaes, eCG exhibits only LH-like activity. To identify the specific biological functions of glycosylated sites in eCG, we constructed the following site mutants of N- and O-linked glycosylation: eCGβ/αΔ56, substitution of α-subunit⁵⁶ N-linked glycosylation site; eCGβ-D/α, deletion of the O-linked glycosylation sites at the β-subunit, and eCGβ-D/αΔ56, double mutant. We produced recombinant eCG (rec-eCG) proteins in Chinese hamster ovary suspension (CHO-S) cells. We examined the biological activity of rec-eCG proteins in CHO-K1 cells expressing the eLH/CG receptor and found that signal transduction activities of deglycosylated mutants remarkably decreased. The EC₅₀ levels of eCGβ/αΔ56, eCGβ-D/α, and eCGβ-D/αΔ56 mutants decreased by 2.1-, 5.6-, and 3.4-fold, respectively, compared to that of wild-type eCG. The Rmax values of the mutants were 56%-80% those of wild-type eCG (141.9 nmol/10⁴ cells). Our results indicate that the biological activity of eCG is greatly affected by the removal of N- and O-linked glycosylation sites in cells expressing eLH/CGR. These results provide important information on rec-eCG in the regulation of specific glycosylation sites and improve our understanding of the specific biological activity of rec-eCG glycosylation sites in equidaes.

• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.269-275
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• 1996

Biosynthesis and secretion of anterior pituitary hormones are under the control of specific hypothalamic stimulatory and inhibitory factors. Among them, Growth Hormone Releasing Hormone (GHRH) is the major stimulator of pituitary somatotrophs activating GH gene expression and secretion. Human GHRH is a polypeptide of 44 amino acids initially isolated from pancreatic tumors, and the gene for the hypothalamic form of GHRH is organized into 5 exons spanning over 10 kilobases (kb) on genomic DNA and encodes a messenger RNA of 700-750 nucleotides. Several neuropeptides classically associated with the hypothalamus have been found in the extrahypothalamic regions, suggesting the existence of novel sources, targets and functions. GHRH-like immunoreactivity has been found in several peripheral sites, including placenta, testis, and ovary, indicating that GHRH may also have regulatory roles in peripheral reproductive organs. Furthermore, higher molecular weight forms of the GHRH transcripts were identified from these organs (1.75 kb in testis; 1.75 and >3 kb in ovary). These tissue-specific expression of GHRH gene suggest the existence of unique regulatory mechanism of GHRH expression and function in these organs. In fact, placenta-specific and testis-specific promoters for GHRH transcripts which are located in about 10 kb upstream region of hypothalamic promoter were reported. The use of unique promoters in extrahypothalamic sites could be refered in a different control of GHRH gene and different functions of the translated products in these tissues. Somatotrophs and lactotrophs have been thought to be derived from a common bipotential progenitor, the somatolactotrophs, which give origins to either phenotypes. Although the precise mechanism responsible for the lactotroph differentiation in the anterior pituitary gland has not been yet clalified, there are several candidators for the generation of lactotrophs. In human, the presence of GHRH peptides with different size from authentic hypothalamic form in the normal anterior pituitary and several types of adenoma were demonstrated. Recently our group found the existence of immunoreactive GHRH and its transcript from the normal rat anterior pituitary (gonadotroph> somatotroph> lactotroph), and the GHRH treatment evoked the increased proliferation rate of anterior pituitary cells in vitro. The transgenic mouse models clearly shown that GHRH or NGF overexpression by anterior pituitary cells induced development of pituitary hyperplasia and adenomas particularly GH-oma and prolactinoma. Taken together, we hypothesize that the pituitary GHRH could serve not only as a modulator of hormone secretion but as a paracrine or autocrine regulator of anterior pituitary cell proliferation and differentiation. Interestingly enough, the expression of Pit-1 homeobox gene (the POU class transcription factor) was confined to somatotrophs, lactotrophs and somatolactotrophs in which GHRH receptors are expressed commonly. Concerning the mechanism of somatolactotroph and lactotroph differentiation in the anterior pituitary, we have focused following two possibilities; (1) changes in the relative levels or interactions of both hypothalamic and intrapituitary factors such as dopamine, VIP, somatostatin, NGF and GHRH; (2) alterations of GHRH-GHRH receptor signaling and Pit-1 activity may be the cause of lactotroph differentiation or pituitary hyperplasia and adenoma formation. Extensive further studies will be necessary to solve these complicated questions.

• 대한의생명과학회지
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• 제13권3호
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• pp.197-206
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• 2007

P2X receptors are membrane-bound ion channels that conduct $Na^+,\;K^+$, and $Ca^{2+}$ in response to ATP and its analogs. There are seven subunits identified so far ($P2X_1-P2X_7$). $P2X_2$ receptors are known to be expressed in a wide range of organs including brains and adrenal grands. PC12 cells are originated from adrenal grand and differentiated by nerve growth factor or pituitary adenylate cyclase activating poly peptide (PACAP). Previous studies indicate that $P2X_2$ receptor activation in PC12 cells couples to $Ca^{2+}-dependent$ release of catecholamine and ATP. It is known that acidic pH potentiates ATP currents at $P2X_2$ receptors. This leads to a hypothesis that $P2X_2$ receptors may play an important role in PC12 cell differentiation, one of the characteristics of which is neurite outgrowth, induced by the hormones under lower pH. In the present study, we isolated several clones which potentiate neurite outgrowth by PACAP in acidic pH (6.8), but not in alkaline pH (7.6). RT-PCR and electrophysiology data indicate that these clones express only functional $P2X_2$ receptors in the absence or presence of PACAP for 3 days. Potentiation of neurite outgrowth resulted from PACAP (100 nM) in acidic pH is inhibited by the two P2X receptor antagonists, suramin and PPADS ($100\;{\mu}M)$ each), and exogenous exprerssion of ATP-binding mutant $P2X_2$ receptor subunit ($P2X_2[K69A]$). However, acid sensing ion channels (ASICs) are not involved in PACAP-induced neurite outgrowth potentiation in lower pH since treatments of an inhibitor of ASICs, amyloride ($10\;{\mu}M$), did not give any effects to neurite extension. The vesicular proton pump ($H^+-ATPase$) inhibitor, bafilomycin (100 nM), reduced neurite extension indicating that ATP release resulted from $P2X_2$ receptor activation in PC12 cells is needed for neurite outgrowth. These were confirmed by activation of mitogen activated protein kinases, such as ERKs and p38. These results suggest roles of ATP and $P2X_2$ receptors in hormone-induced cell differentiation or neuronal synaptogenesis in local acidic environments.

• 대한화장품학회지
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• 제25권2호
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• pp.45-57
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• 1999

멜라닌세포는 신경능에서 기원한 세포로서 멜라닌을 생성하여 피부를 자외선으로부터 보호하는 중요한 기능을 수행하고 있다. 멜라닌세포는 수지상 돌기를 갖는 등 신경세포와 형태학적으로 유사하며 많은 신호 전달 물질, 성장 인자 등에 대한 수용체를 공통적으로 갖고 있어 발생학적 기원이 신경 세포와 같음을 보여주는 많은 특징들이 있다. 멜라닌세포는 자외선, 염증 등의 외부조건, alpha-MSH 등의 호르몬, IL-1, TNF-alpha, GM-CSF 등 의 싸이토카인, leukotriene 등 여러 가지 인자의 영향을 받고 있다. 또한 멜라닌세포로부터 멜라닌이 생성되기 위해서는 tyrosinase, TRP-1, TRP-2 등 여러 가지 유전자와 그에 해당하는 효소들의 작용, 또한 멜라닌이 각질형성세포로 이동하는 과정에 역시 여러 종류 의 유전자가 관여하고 있어 피부의 색소형성 과정을 이해하기 위해서는 이러한 과정을 복합적으로 이해하여야 한다(그림 1). 그러나 아직까지 멜라닌세포의 멜라닌 형성 과정과 증식, 사망 과정이 정확히 어떻게 진행되는지에 대한 연구가 부족한 실정이다.

• Osteoporosis and Sarcopenia
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• 제2권3호
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• pp.140-155
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• 2016

Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.

• 한국발생생물학회지:발생과생식
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• 제10권2호
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• pp.85-92
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• 2006

본 논문은 포유동물 난소에서의 신속한 프로게스테론(P4) 선호 전달경로에 관해 현재 통용되는 지식을 요약하였다. P4는 안드로겐과 에스트로겐 합성 과정에서의 중요한 중간 산물이면서 그 자체로도 배란, 난포폐쇄(atresia), 황체형성과정(luteinization)에서 결정적인 역할을 하며, 모든 포유동물의 초기 임신 유지에 필수적이다. 이와 같은 생리적인 중요성에도 불구하고 포유동물 난소에서의 정확한 P4 작용기작은 아직까지도 완전히 알려져 있지 않다. 이러한 관점에서 볼 때, 비유전자 수준이면서 전사와 무관한 P4의 세포내 작용을 매개하는 수용체의 실체에 관해 오래 동안 계속된 의문과 논란은 과학적인 흥미를 유발하는 생식생리학의 주요 관심사이다. 포유류 난소에서 P4는 1) 잘 알려진 유전자 수준의 경로(genomic pathway)인 호르몬이 소위 고전적인 세포 내의 수용체에 결합하고, 이어 리간드-호르몬 복합체가 전사조절물질로 작용하여 표적 유전자 발현을 조절하거나, 2) 유전자에 직접 작용하지 않기 때문에 비유전자 수준이라 불리우는 경로(non-genomic pathway)로 작용한다. P4의 비유전자 수준 작용의 주요한 특징은 (i) 신속하고, (ii) 전사억제제에 반응하지 않고, (iii) 세포막과 연관된 물질들에 의해 신호가 전달된다. 아마도 난소에서 P4의 비유전자 수준 작용은 (a) 세포막 또는 그 근처에 위치한 고전적인 P4 수용체(PGR), (b) 세포막 프로게스틴 수용체(membrane progestin receptors; MPR $\alpha$, MPR $\beta$ and MPR $\gamma$) 패밀리, (c) progesterone receptor membrane component I(PGRMC1), 그리고 (d) serpine I mRNA binding protein(SERBP1)의 세포막 복합체에 의해 매개되는 것으로 추정된다. 포유류 난소에서의 P4 작용에 대한 완전한 이해를 위해서는 향후 많은 연구가 필요할 것이다.

• 한국발생생물학회지:발생과생식
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• 제6권1호
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• pp.55-66
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• 2002

배아줄기세포(embryonic stem cell, ESC)는 미분화상태로 지속적인 계대가 가능하며, 정상 핵형과 전 분화능(pluripotency)을 가져 생체내-외에서 분화 유도시 삼배엽성의 모든 세포로 분화 가능하다. ESC를 feeder 세포 없이 부유배양하면 배아체(embryoid body, EB)를 형성하고, 초기 배아 발생과 유사한 분화 양상을 갖는다. ESC의 분화 유도가 초기배아 발생처럼 생식호르몬(GTH: FSH, LH; steroids)의 영향을 받는지는 불명하다. 본 연구는 ESC가 분화과정중 생식호르몬처리에 의해 그들 수용체가 발현되는가를 알아보고자 하였다. 순계혈통 생쥐인 C57BL/6J에서 과배란 유도후 포배를 수획하고, 유사분열적으로 불활성화된 feeder 세포와 공배양하여, 계대배양 하는 중 배아줄기세포주(JHYl)를 확립하였다. JHY1의 alkaline phosphatase 활성과 SSEA-1, 3, 4 발현을 통해 ESC임을 확인하였다. Feeder 세포 없이 ESC를 계대배양 후 호르몬처리(FSH LH E$_2$, P$_4$, T)하에서 5일 동안 부유배양하여 배아체를 형성시키고, 이후 7일 동안 부착배양하여 분화를 유도하였다. GTH와 스테로이드의 수용체 발현 실험에서 ESC에 E$_2$ 처리에 의한 LHR의 발현 증가를 제외한 나머지 호르몬 처리군에서 ESC보다 낮은 생식호르몬의 수용체 발현이 관찰되었다. 생식호르몬을 농도별 수용체 발현 정도는 증감되지 않았다. 미분화 ESC 표지유전자인 Oct-4는 호르몬 처리군에서도 발현되었다. 각 배엽의 표지유전자들(영양세포, handl; 외배엽성, keratin와fgf-5; 중배엽성, enolase와 $\alpha$ -globin; 내배엽성, gata-4와 $\alpha$ -fetoprotein) 등의 발현 양상을 조사한 결과 호르몬 처리후 내배엽성 표지유전자외에는 발현 증가가 관찰되지 않았다. 즉 생식호르몬에 의해 gata-4, $\alpha$-fetoprotein의 발현이 증가되는 것으로 보아 내배엽성 계열로의 분화 유도가 이루어진 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권4호
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• pp.335-356
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• 1997

Injection of bovine growth hormone (bGH) to lactating dairy cows increases milk yield and yields of milk components including fat. It is generally believed that most of the anabolic effects derived from bGH in animal tissues are primarily mediated by IGF-1. IGF-1 is a strong anabolic peptide in the plasma of animals and exerts mitogenic and metabolic effects on target cells. Contrary to most protein hormones, the majority of IGF-1 in circulation is bound to the binding proteins (IGFBPs) which are known to be responsible for modifying the biological actions of IGF-1, thus making determinations of IGF-1 actions more difficult. On the other hand, fat is a major milk component and the greatest energy source in milk. Currently, the fat content of milk is one of the major criteria used in determining milk prices. It has been known that flavor and texture of dairy products are mainly affected by milk fat and its composition. Acetyl-CoA carboxylase (ACC) is the rate limiting enzyme which catalyzes the conversion of acetyl-CoA to malonyl-CoA for fatty acid synthesis in 1ipogenic tissues of animals including bovine lactating mammary glands. In addition to the short-tenn hormonal regulation of ACC by changes in the catalytic efficiency per enzyme molecule brought about by phosphorylation and dephosphorylation of the enzyme, the long-term hormonal regulation of ACC by changes in the number of enzyme molecules plays an essential role in control of ACC and lipogenesis. Insulin, at supraphysiological concentrations, binds to IGF-1 receptors, thereby mimicking the biological effects of IGF-1. The receptors for insulin and IGF-1 share structural and functional homology. Furthermore, epidermal growth factor increased ACC activity in rat hepatocytes and adipocytes. Therefore, it can be assumed that IGF-1 mediating bGH action may increase milk fat production by stimulation ACC with phosphorylation (short term) and/or increasing amounts of the enzyme proteins (long term). Consequently, the main purpose of this paper is to give the readers not only the galactopoietic effects of bGH, but also the insight of bGH action with regard to stimulating milk fat synthesis from the whole body to the molecular levels.