Mammalian sex hormones in plants

The occurrence of mammalian sex hormones and their physiological role in plants is reviewed. These hormones, such as 17beta-estradiol, androsterone, testosterone or progesterone, were present in 60-80% of the plant species investigated. Enzymes responsible for their biosynthesis and conversion were also found in plants. Treatment of the plants with sex hormones or their precursors influenced plant development: cell divisions, root and shoot growth, embryo growth, flowering, pollen tube growth and callus proliferation. The regulatory abilities of mammalian sex hormones in plants makes possible their use in practice, especially in plant in vitro culture.     

Post-translational modifications in secreted peptide hormones in plants

More than a dozen secreted peptides are now recognized as important hormones that coordinate and specify cellular functions in plants. Recent evidence has shown that secreted peptide hormones often undergo post-translational modification and proteolytic processing, which are critical for their function. Such 'small post-translationally modified peptide hormones' constitute one of the largest groups of peptide hormones in plants. This short review highlights recent progress in research on post-translationally modified peptide hormones, with particular emphasis on their structural characteristics and modification mechanisms.     

An electrophoretic analysis of human glycoprotein hormones and their subunits]

Stability of heterodimers of human glycoprotein hormones with gonadotropic and thyrotropic activities in sodium dodecylsulfate (SDS) under non-reducing conditions at low temperature permits to resolve the native molecules of these hormones in SDS-PAG and to distinguish from their dissociated subunits by electrophoretical mobility. The analysis of dimers and alpha-, beta-subunits in one polyacrylamide gel allows to detect certain human glycoprotein hormones and to study some of their physico-chemical properties. Using two polyclonal antisera against human LH and FSH by the Western blot immunoassay it was shown that heterodimers as well as alpha and beta subunits after SDS-PAGE retain antigenic activity of native hormones. The method gave possibility to characterize the specificity of the given sera to different glycoprotein hormones.     

Invertebrate neuropeptide hormones

The development of a long-term research program on the neurosecretory hormones of arthropods is described. The purification and full characterization of the first invertebrate neurohormones, the red pigment-concentrating hormone (RPCH) and the distal retinal pigment hormone (DRPH) demonstrated that they are peptides, an octapeptide and an octadecapeptide, respectively. Physiological function studies with the pure hormones and their synthetic preparations showed that the RPCH acts as a general pigment-concentrating hormone (PCH), and that the DRPH, in addition to its light-adaptive function, also constitutes a general pigment-dispersing hormone (PDH). In the regulation of the color-adaptation of the animals, the two hormones act as antagonists. The chromatophorotropic activities are widely distributed within the arthropod neuroendocrine systems. Purification of the pigment-concentrating activities from the locust corpora cardiaca lead to the isolation and characterization of the first insect neurohormones, the adipokinetic hormones (AKH I and AKH II). These two hormones, AKH I being a decapeptide and AKH II being an octapeptide, are close structural analogs to the crustacean PCH, demonstrating a common evolution of arthropod neurohormones. The hormones of this PCH-family all cross-react, but structure-function studies of the hormones show that quite different parts of their structure are involved in their binding to the various receptors.     

Immunocytochemical localization of atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide in human pancreatic adenocarcinomas.

We recently found that four peptide hormones synthesized by the same gene completely inhibit the growth of human pancreatic adenocarcinomas in athymic mice. The present immunocytochemical investigation was designed to determine where in the adenocarcinomas these peptide hormones localize. Atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide localized to the cytoplasm and nucleus of the human pancreatic adenocarcinomas, which is consistent with their ability to decrease DNA synthesis in the nucleus of this cancer. In this first investigation of where these peptide hormones with anticancer effects localize in any cancer, these peptide hormones also localized to the endothelium of capillaries and fibroblasts within these cancers. This is the first demonstration of growth-inhibiting peptide hormones localizing to the nucleus, where they inhibit DNA synthesis and may interact with growth-promoting hormones that localize there as the etiology of their ability to inhibit the growth of adenocarcinomas both in vitro and in vivo.     

Participation of thyroid hormones in the regulation of the genetic activity of normal and transformed human cells]

It is shown that 125J-thyroid hormones are localized on the structures of the interphasic nucleus and metaphasic chromosomes of cultured fibroblasts of 8--10-day human embryos. At the same time, the labelled thyroid hormones, though localizing in the interphasic nuclei of HeLa cells, are not accepted, unlike normal cells, by their metaphasic chromosomes. It is suggested that during transformation the acceptor ares of the HeLa cells genome lost their property to bind their own receptor complexes with thyroid hormones.     

Plant hormones: metabolism, signaling and crosstalk

Plants synthesize various hormones in response to environmental cues and developmental signals to ensure their proper growth and development.Elucidation of the molecular mechanisms by which plant hormones control growth and development contributes to our understanding of fundamental plant biology and provides tools to improve crops.Because of their critical roles in plant growth and development, plant hormones have been studied extensively since the early days of plant biology.     

昆虫中存在高等动物性激素吗？

性激素在调控高等动物附性器官的发育和成熟, 激发和维持第二性征以及增进两性细胞的结合和孕育能力等方面有不可替代的作用。性激素包括雌性激素和雄性激素, 主要存在于哺乳动物中。随着检测技术的不断进步, 越来越多的研究显示性激素并非高等动物所特有。包括一些昆虫在内的无脊椎动物中同样含有性激素, 家蚕Bombyx mori、欧洲兔虱Spilopsyllus cuniculi等昆虫被高等动物性激素或者性激素类似物处理过后能产生一定的应答, 且有研究报道昆虫中同样含有羟基固醇脱氢酶等高等动物催化合成性激素的某些酶类。本文以雌激素为例, 在全面总结高等动物雌激素在昆虫中的鉴定、代谢、生理作用等相关研究的基础上, 分析昆虫对高等动物性激素的合成、应答以及高等动物性激素在昆虫中作为昆虫“性激素”的可能性。雌激素作为高等动物的主要雌性激素, 在很多昆虫组织或个体提取物中同样存在。目前的研究已经证实家蚕等昆虫能代谢雌激素, 用雌激素处理某些昆虫后也能影响该昆虫的生理过程。雌激素对高等动物许多生理过程都具有显著的调节作用, 但主要还是作为性激素调节性别相关的生理过程。为了明确脊椎动物雌激素在昆虫中是否存在且发挥着性激素功能, 相关的研究可以主要从3个方面着手: (1) 昆虫中能否检测到高等动物雌激素类似物存在; (2) 雌激素是否也能让昆虫产生雌性相关的生理应答,从昆虫中提取的雌激素类似物能否令高等动物产生雌性特异的响应; (3)昆虫是否能够合成雌激素, 体内是否存在参与催化合成雌激素的酶类。     

Lack of effects of thyroid hormones on human erythrocyte acetylcholine esterase

Effects of thyroid hormones and their metabolites such as L-T1, L-T2, L-T3 and L-T4 on human erythrocyte acetylcholine esterase were studied. The activity of the enzyme of intact erythrocytes was not affected by these hormones, though studied under various conditions. The physiological significance of the binding of these hormones to erythrocyte membranes remains unclear. Our results indicate that the acetylcholine esterase is not a suitable enzyme for cytochemical bioassay for thyroid hormones.     

Interaction of steroid hormones with glutamate dehydrogenase]

The inhibitory action of sex hormones on the glutamate dehydrogenase activity is due to their binding to the enzyme protein. No binding of sex hormones to glutamate dehydrogenase is observed in the presence of L-amino acids, preventing the enzyme dissociation. Under those conditions the enzyme sensitivity to the inhibitory action of the hormones sharply decreases.     

Direct binding and activation of protein kinase C isoforms by steroid hormones

The non-genomic action of steroid hormones regulates a wide variety of cellular responses including regulation of ion transport, cell proliferation, migration, death and differentiation. In order to achieve such plethora of effects steroid hormones utilize nearly all known signal transduction pathways. One of the key signalling molecules regulating the non-genomic action of steroid hormones is protein kinase C (PKC). It is thought that rapid action of steroids hormones results from the activation of plasma membrane receptors; however, their molecular identity remains elusive. In recent years, an increasing number of studies have pointed at the selective binding and activation of specific PKC isoforms by steroid hormones. This has led to the hypothesis that PKC could act as a receptor as well as a transducer of the non-genomic effects of these hormones. In this review we summarize the current knowledge of the direct binding and activation of PKC by steroid hormones.     

Mobilization of intracellular calcium by glucagon and cyclic AMP analogues in isolated rat hepatocytes

Separate or combined addition of cyclic AMP-dependent and Ca2+-linked hormones to isolated rat hepatocytes suspended in a low Ca2+ medium reduced the total cellular Ca. When the hormones were administered together, their effects were not additive. This suggests that both types of hormones mobilize Ca2+ from a common intracellular pool. In the presence of 1.8 mM extracellular Ca2+, the Ca2+ influx counterbalanced or even exceeded the hormone-induced Ca2+ loss, depending on the ability of the hormones to stimulate the Ca2+ influx.     

Protein kinases: Signaling molecules controlling ovarian functions

The present focus survey represents a review of current knowledge concerning involvement of protein kinases in control of basic ovarian functions in mammals. Ovarian cells produce a number of protein kinases, whose expression depends on type of cells, their state and action of hormones and other protein kinases. A number of protein kinases are involved in control of ovarian cell proliferation, apoptosis, oocyte maturation, hormone release, reception and response to hormones, as well as in mediating action of hormones on these ovarian functions. Protein kinases and their regulators could be used for characterization, prediction and control of ovarian folliculogenesis and atresia, corpus luteum functions, oocyte maturation, fertility, release of hormones, response of ovarian structures to hormonal regulators, as well as for treatment of some reproductive disorders.     

Prosequence-mediated disulfide coupled folding of the peptide hormones guanylin and uroguanylin

In contrast to their prohormones the mature peptide hormones guanylin and uroguanylin are not able to fold to their native disulfide connectivities upon oxidative folding. Structural properties of both peptide hormones and their precursor proteins as well as the role of their prosequences in proper disulfide coupled folding are reviewed. In addition, the structural behavior of a proguanylin mutant that closely resembles prouroguanylin has been investigated to gain further insight into structural properties of this homologous precursor protein.     

Non-conventional locations of hormone receptors (binding sites). A review

Recent findings on the noncanonical positions of some well-known extracellular mediators and their receptors are reviewed. Peptide hormones (insulin) and/or their binding sites (cell membrane insulin receptor, nuclear insulin receptor); steroid hormones (corticosteroids and estrogens) and their putative membrane receptors are in the scope of this paper. The possible roles of these unusually located receptors in the intracellular signal propagation and physiological responses are also discussed.     

Aging-related changes in ovarian hormones, their receptors, and neuroendocrine function

Ovarian steroid hormones exert a broad range of effects on the body and brain. In the nervous system, estrogen and progesterone have crucial feedback actions on the hypothalamic neurons that drive the reproductive axis. In addition, hormones exert a variety of actions on other traditionally nonreproductive functions such as cognition, learning and memory, neuroprotection, mood and affective behavior, and locomotor activity. The actions of hormones on the hypothalamus are largely mediated by their nuclear hormone receptors, the two estrogen receptors, ERalpha and ERbeta, and the two progesterone receptor isoforms, PR-A and PR-B. Thus, changes in the circulating concentrations of estrogens and progestins during the life cycle can result in differential activation of their receptors. Furthermore, changes in the numbers, activity, and distribution of hypothalamic ERs and PRs can occur as a function of developmental age. The purpose of this article is to review the literature on the causes and consequences of alterations in steroid hormones, their neural receptors, and their interactions on reproductive senescence. We have also discussed several important experimental design considerations, focusing on rodent models in current use for understanding the mechanisms of menopause in women.     

Auxin-oxylipin crosstalk: relationship of antagonists

Stephan Pollmann (Corresponding author) Phytohormones regulate a wide array of developmental processes throughout the life cycle of plants. Herein, the various plant hormones may interact additively, synergistically, or antagonistically. By their cooperation they create a delicate regulatory network whose net output largely depends on the action of specific phytohormone combinations rather than on the independent activities of separate hormones. While most classical studies of plant hormonal control have focused mainly on the action of single hormones or on the synergistic interaction of hormones in regulating various developmental processes, recent work is beginning to shed light on the crosstalk of nominally antagonistic plant hormones, such as gibberellins and auxins with oxylipins or abscisic acid. In this review, we summarize our current understanding of how two of the first sight antagonistic plant hormones, i.e. auxins and oxylipins, interact in controlling plant responses and development.     

Anterior pituitary hormones, stress, and immune system homeostasis

An extensive, and controversial, literature concluding that prolactin (PRL), growth hormone (GH), insulin-like growth factor-I (IGF-I), and thyroid hormones are critical immunoregulatory factors has accumulated. However, recent studies of mice deficient in the production of these hormones or expression of their receptors indicate that there are only a few instances in which these hormones are required for lymphocyte development or antigen responsiveness. Instead, a case is made that their primary role is to counteract the effects of negative immunoregulatory factors, such as glucocorticoids, which are produced when the organism is subjected to major stressors. The immunoprotective actions of PRL, GH, IGF-I, and/or thyroid hormones in these instances may ensure immune system homeostasis and reduce the susceptibility to stress-induced disease. These immuno-enhancing effects could be exploited clinically in instances where the immune system is depressed due to illness or various treatment regimens.