• Journal of Plant Biotechnology
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• 제44권1호
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• pp.61-68
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• 2017

GASA는 GA에 의해 조절되는 식물 유전자로서, 여러 식물에 보존되어 있고 다양한 조직에서 식물의 생장과 발달 및 스트레스 반응에 관여하는 것으로 알려져 있다. 본 연구에서는 GASA 유전자를 현사시나무(Populus alba ${\times}$ P. glandulosa)에서 분리하여 이를 PagGASA라 명명하고, 유전자의 구조와 발현특성을 조사하였다. PagGASA 유전자는 95개의 아미노산으로 구성된 단백질을 암호화하며, 아미노 말단에 시그널 펩티드 영역과 카르복시 말단에 12개 시스테인 잔기가 보존되어 있다. PagGASA는 현사시나무의 염색체에 1 ~ 2 copy 존재하며, 꽃과 뿌리에서 높게 발현하였다. 또한 PagGASA는 GA 뿐 아니라 ABA와 JA, SA와 같은 스트레스 관련 식물 호르몬의 처리에 의해서 발현이 증가하는 것으로 나타났다. 현사시나무에 형질전환하여 PagGASA를 과발현시킨 결과 건조 내성에 효과가 있음을 확인하였다. 따라서 PagGASA는 스트레스 관련 식물 호르몬 신호전달과 연결되어 건조 스트레스 방어기작에서 중요한 역할을 할 것으로 생각된다.

• Journal of Plant Biotechnology
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• 제32권4호
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• pp.251-256
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• 2005

Cytokinin은 식물의 성장과 발달에 중요한 역할을 하는 필수 호르몬이다. Cytokinin의 작용 기작을 이해하기 위하여 단백체를 이용하여 cytokinin 관련 단백질들을 동정하였다. 대조구와 t-zeatin을 처리한 애기장대로부터 추출한 단백질을 이차원 전기영동하여 분석하였다. 발현양에 차이가 있는 단백질 spot들을 MALDI-TOF 단백질 질량분석기와 database 검색을 통하여 동정하였다. 그 결과 t-zeatin 처리에 의하여 발현이 증가하는 10개의 단백질과 감소하는 한 개의 단백질을 분리할 수 있었다. Cytokinin에 의하여 발현이 증가하는 단백질은 pollen allergen like protein, L-ascorbate peroxidase, tetrapyrrole methylase family protein, SGT1 protein homolog, disease resistance related protein, maternal embryogenesis control protein, paxneb related protein, gluthathione S-transferase, 그리고 IAA amino acid hydrolase homolog들로 밝혀졌다.

• 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.

• 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.

• 농업과학연구
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• 제8권1호
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• pp.64-71
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• 1981

돼지에 있어서 분만전후(分娩前後)의 혈청중(血淸中) peptide 및 steroid hormone 수준(水準)의 변화(變化)를 구명(究明)하기 위(爲)하여 8두(頭)의 임신돈(妊娠豚)을 대상(對象)으로 분만전(分娩前) 20일(日)부터 분만후(分娩後) 20일(日)까지 혈청중(血淸中)의 FSH, LH, prolactin, estradiol-$17{\beta}$, progesterone 및 cortisol의 농도변화(濃度變化)를 radioimmunoassay 방법(方法)에 의(依)하여 측정(測定)하였다. 혈청(血淸) FSH의 농도(濃度)는 분만전후(分娩前後)에 큰 변화(變化)가 없었으며, $8.1{\pm}1.8mIU/ml$에서 $9.0{\pm}2.6mIU/ml$의 사이에 있었다. LH농도(濃度)는 분만(分娩) 20일전(日前)에 $2.6{\pm}0.3mIU/ml$이던것이 분만일(分娩日)에는 $3.9{\pm}1.1mIU/ml$로 증가(增加)하였으며, 분만후(分娩後) 2일(日)에는 $3.2{\pm}0.9mIU/ml$로 감소(減少)되었고, 그 후(後)로는 거의 비슷한 수준(水準)을 유지(維持)하였다. Prolactin의 농도(濃度)는 분만일(分娩日)에 $68.5{\pm}9.5ng/ml$로 최고수준(最高水準)을 나타냈으며, 분만당일(分娩當日) 전후(前後)에 비교적(比較的) 높은 수준(水準)을 나타냈다. Estradiol-$17{\beta}$는 분만전(分娩前) 6일(日)에 $205.0{\pm}29.5pg/ml$로 증가(增加)하였고, 분만일(分娩日)에는 $425.0{\pm}35.6pg/ml$로 급증(急增)하였으나 분만후(分娩後) 2일(日)에는 $59.5{\pm}7.8pg/ml$로 다시 감소(感少)했다. Progesterone 농도(濃度)는 분만전(分娩前) 20일(日)부터 6일(日)까지는 $18.4{\pm}1.6{\sim}20.2{\pm}2.1ng/ml$사이에 있었으나, 분만전(分娩前) 2일(日)부터 감소(減少)하기 시작(始作)하여 분만일(分娩日)에는 $2.6{\pm}0.8ng/ml$까지 감소(減少)하였고, 분만후(分娩後) 2일(日)에는 $0.9{\pm}0.3ng/ml$에 도달(到達) 하였으며, 그 후(後)로는 거의 같은 수준(水準)을 유지(維持)하였다. Cortisol은 분만일(分娩日)에 $86.5{\pm}10.5ng/ml$로 최고수준(最高水準)을 나타냈다.

• Toxicological Research
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• 제8권2호
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• pp.343-357
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• 1992

Tumor necrosis factor-${\alpha}$(TNF), a polypeptide hormone secreted primarily by activated macrophages, was originally identified on the basis of its ability to cause hemorrhagic necrosis and tumor regression in vivo. Subsequently, TNF has been shown to be an important component of the host responses to infection and cancer and may mediate the wasting syndrome known as cachexia. These systemic actions of TNF are reflected in its diverse effects on target cells in vitro. TNF initiates its diverse cellular actions by binding to specific cell surface receptors. Although TNF receptors have been identified on most of animal cells, regulation of these receptors and the mechanisms which transduce TNF receptor binding into cellular responses are not well understood. Therefore, in the present study, the mechanisms how TNF receptors are being regulated and how TNF receptor binding is being transduced into cellular responses were investigated in rat liver plasma membranes (PM) and ME-180 human cervical carcinoma cell lines. $^{125}I$-TNF bound to high ($K_d=1.51{\pm}0.35nM$)affinity receptors in rat liver PM. Solubilization of PM with 1% Triton X-100 increased both high affinity (from $0.33{\pm}0.04\;to\;1.67{\pm}0.05$ pmoles/mg protein) and low affinity (from $1.92{\pm}0.16\;to\;7.57{\pm}0.50$ pmoles/mg protein) TNF binding without affecting the affinities for TNF, suggesting the presence of a large latent pool of TNF receptors. Affinity labeling of receptors whether from PM or solubilized PM resulted in cross-linking of $^{125}I$-TNF into $M_r$ 130 kDa, 90 kDa and 66kDa complexes. Thus, the properties of the latent TNF receptors were similar to those initially accessible to TNF. To determine if exposure of latent receptors is regulated by TNF, $^{125}I$-TNF binding to control and TNF-pretreated membranes were assayed. Specific binding was increased by pretreatment with TNF (P<0.05), demonstrating that hepatic PM contains latent TNF receptors whose exposure is promoted by TNF. Homologous up-regulation of TNF receptors may, in part, be responsible for sustained hepatic responsiveness during chronic exposure to TNF. As a next step, the post-receptor events induced by TNF were examined. Although the signal transduction pathways for TNF have not been delineated clearly, the actions of many other hormones are mediated by the reversible phosphorylation of specific enzymes or target proteins. The present study demonstrated that TNF induces phosphorylation of 28 kDa protein (p28). Two dimensional soidum dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) resolved the 28kDa phosphoprotein into two isoforms having pIs of 6.2 and 6.1. The pIs and relative molecular weight of p28 were consistent with those of a previously characterized mRNA cap binding protein. mRNA cap binding proteins are a class of translation initiation factors that recognize the 7-methylguanosine cap structure found on the 5' end of eukaryotic mRNAs. In vitro, these proteins are defined by their specific elution from affinity columns composed of 7-methylguanosine 5'-triphosphate($m^7$GTP)-Sepharose. Affinity purification of mRNA cap binding proteins from control and TNF treated ME-180 cells proved that TNF rapidly stimulates phosphorylation of an mRNA cap binding protein. Phosphorylation occurred in several cell types that are important in vitro models of TNF action. The mRNA cap binding protein phosphorylated in response to TNF treatment was purifice, sequenced, and identified as the proto-oncogene product eukaryotic initiation factor-4E(eIF-4E). These data show that phosphorylation of a key component of the cellular translational machinery is a common early event in the diverse cellular actions of TNF.