Deletion of Gαq/11 or Gαs proteins in gonadotropes differentially affects gonadotropin production and secretion in mice

Endocrinology ◽  
2021 ◽  
Author(s):  
George A Stamatiades ◽  
Chirine Toufaily ◽  
Han Kyeol Kim ◽  
Xiang Zhou ◽  
Iain R Thompson ◽  
...  
Keyword(s):  
Hypogonadotropic Hypogonadism ◽  
Pulse Frequency ◽  
Conditional Knockout ◽  
High Pulse Frequency ◽  
High Pulse ◽  
Males And Females ◽  
G Protein Coupled ◽  
In Vitro Data

Abstract GnRH regulates gonadal function via its stimulatory effects on gonadotropin production by pituitary gonadotrope cells. GnRH is released from the hypothalamus in pulses and GnRH pulse frequency differentially regulates FSH and LH synthesis and secretion. The GnRH receptor (GnRHR) is a G protein-coupled receptor that canonically activates Gαq/11-dependent signaling upon ligand binding. However, the receptor can also couple to Gαs and in vitro data suggest that toggling between different G proteins may contribute to GnRH pulse frequency decoding. For example, as we show here, knockdown of Gαs impairs GnRH-stimulated FSH synthesis at low, but not high pulse frequency in a model gonadotrope-derived cell line. We next used a Cre-lox conditional knockout approach to interrogate the relative roles of Gαq/11 and Gαs proteins in gonadotrope function in mice. Gonadotrope-specific Gαq/11 knockouts exhibit hypogonadotropic hypogonadism and infertility, akin to the phenotypes seen in GnRH- or GnRHR-deficient mice. In contrast, under standard conditions, gonadotrope-specific Gαs knockouts produce gonadotropins at normal levels and are fertile. However, the LH surge amplitude is blunted in Gαs knockout females and post-gonadectomy increases in FSH and LH are reduced in both males and females. These data suggest that GnRH may signal principally via Gαq/11 to stimulate gonadotropin production, but that Gαs plays important roles in gonadotrope function in vivo when GnRH secretion is enhanced.

scholarly journals Hypothesis

2016 ◽  
Vol 22 (1) ◽  
pp. 51-53 ◽  
Author(s):  
Jonathan M. Powell ◽  
Emanuel Ebin ◽  
Steven Borzak ◽  
Anastasios Lymperopoulos ◽  
Charles H. Hennekens
Keyword(s):  
G Protein ◽  
Wall Thickness ◽  
Basic Research ◽  
Left Ventricular ◽  
Conditional Knockout ◽  
Receptor Kinase ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

The hypothesis that paroxetine decreases morbidity and mortality in patients with heart failure (HF) is plausible but unproven. Basic research demonstrates that inhibition of G protein-coupled receptor kinase 2 (GRK2) both in vitro and in vivo in the myocardium may be beneficial. G protein-coupled receptor kinase 2 antagonism is purported to exert cardioprotective effects immediately following myocardial injury by blunting toxic overstimulation on a recently injured heart. In addition, chronic overexpression of GRK2 inhibits catecholamine induction of vital positive chronotropic and ionotropic effects required to preserve cardiac output leading to worsening of congestive HF. In cardiac-specific GRK2 conditional knockout mice, there is significant improvement in left ventricular wall thickness, left ventricular end-diastolic diameter (LVEDD), and ejection fraction (EF) compared to controls. Paroxetine is a selective serotonin reuptake inhibitor which was recently shown to have the ability to directly inhibit GRK2 both in vitro and in vivo. At physiologic temperatures, paroxetine inhibits GRK2-dependent phosphorylation of an activated G-protein-coupled receptor with a half maximal inhibitory concentration of 35 micromoles, a substantially greater affinity than for other G protein-coupled receptor kinases. In a randomized trial in mice with systolic HF and depressed EF postmyocardial infarction, those treated with paroxetine had a 30% increase in EF, improved contractility, and LVEDD and wall thickness compared to those treated with medical therapy alone. While further basic research may continue to elucidate plausible mechanisms of benefit and observational studies will contribute important relevant information, large scale randomized trials designed a priori to do so are necessary to test the hypothesis.

A Review on Melatonin’s Effects in Cancer: Potential Mechanisms

2018 ◽  
Vol 18 (7) ◽  
pp. 985-992 ◽  
Author(s):  
Aysegul Hanikoglu ◽  
Ertan Kucuksayan ◽  
Rana Cagla Akduman ◽  
Tomris Ozben
Keyword(s):  
Systematic Review ◽  
Antioxidant Activity ◽  
Membrane Receptors ◽  
Cancer Development ◽  
Secretory Product ◽  
Prevention And Treatment ◽  
G Protein Coupled

This systematic review aims to elucidate the role of melatonin (N-acetyl-5-metoxy-tryptamine) (MLT) in the prevention and treatment of cancer. MLT is a pineal gland secretory product, an evolutionarily highly conserved molecule; it is also an antioxidant and an impressive protector of mitochondrial bioenergetic activity. MLT is characterized by an ample range of activities, modulating the physiology and molecular biology of the cell. Its physiological functions relate principally to the interaction of G Protein-Coupled MT1 and MT2 trans-membrane receptors (GPCRs), a family of guanidine triphosphate binding proteins. MLT has been demonstrated to suppress the growth of various tumours both, in vivo and in vitro. In this review, we analyze in depth, the antioxidant activity of melatonin, aiming to illustrate the cancer treatment potential of the molecule, by limiting or reversing the changes occurring during cancer development and growth.

scholarly journals Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 122
Author(s):  
Catharina Latz ◽  
Thomas Asshauer ◽  
Christian Rathjen ◽  
Alireza Mirshahi
Keyword(s):  
Surgical Techniques ◽  
Numerical Aperture ◽  
Optical Breakdown ◽  
Pulse Frequency ◽  
Low Energy ◽  
Human Cornea ◽  
Energy Concept ◽  
High Pulse Frequency ◽  
Fs Laser ◽  
High Pulse

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

Use of Toxicokinetics in Risk Assessment Based on In Vitro Data

1993 ◽  
Vol 21 (2) ◽  
pp. 173-180
Author(s):  
Gunnar Johanson
Keyword(s):  
Risk Assessment ◽  
Whole Body ◽  
External Exposure ◽  
Target Dose ◽  
Toxic Response ◽  
Route Of Exposure ◽  
Vitro Data ◽  
In Vitro Data

This presentation addresses some aspects of the methodology, advantages and problems associated with toxicokinetic modelling based on in vitro data. By using toxicokinetic models, particularly physiologically-based ones, it is possible, in principle, to describe whole body toxicokinetics, target doses and toxic effects from in vitro data. Modelling can be divided into three major steps: 1) to relate external exposure (applied dose) of xenobiotic to target dose; 2) to establish the relationship between target dose and effect (in vitro data, e.g. metabolism in microsomes, partitioning in tissue homogenates, and toxicity in cell cultures, are useful in both steps); and 3) to relate external exposure to toxic effect by combining the first two steps. Extrapolations from in vitro to in vivo, between animal and man, and between high and low doses, can easily be carried out by toxicokinetic simulations. In addition, several factors that may affect the toxic response by changing the target dose, such as route of exposure and physical activity, can be studied. New insights concerning the processes involved in toxicity often emerge during the design, refinement and validation of the model. The modelling approach is illustrated by two examples: 1) the carcinogenicity of 1,3-butadiene; and 2) the haematotoxicity of 2-butoxyethanol. Toxicokinetic modelling is an important tool in toxicological risk assessment based on in vitro data. Many factors, some of which can, and should be, studied in vitro, are involved in the expression of toxicity. Successful modelling depends on the identification and quantification of these factors.

Imidazolidinyl urea activates mast cells via MRGPRX2 to induce non-histaminergic allergy

2021 ◽  
Author(s):  
Jiapan Gao ◽  
Delu Che ◽  
Xueshan Du ◽  
Yi Zheng ◽  
Huiling Jing ◽  
...  
Keyword(s):  
Contact Dermatitis ◽  
Mast Cells ◽  
Pharmaceutical Products ◽  
Drug Induced ◽  
Inflammatory Infiltration ◽  
Local Inflammatory Response ◽  
Allergic Contact ◽  
G Protein Coupled

Abstract Imidazolidinyl urea (IU) is used as an antimicrobial preservative in cosmetic and pharmaceutical products. IU induces allergic contact dermatitis, however, the mechanism has not yet been elucidated. Mas-related G protein-coupled receptor-X2 (MRGPRX2) triggers drug-induced pseudo-allergic reactions. The aims of this study were to determine whether IU activated mast cells through MRGPRX2 to further trigger contact dermatitis. Wild-type (WT) and KitW-sh/HNihrJaeBsmJNju (MUT) mice were treated with IU to observe its effects on local inflammation and mast cells degranulation in vivo. Laboratory of allergic disease 2 cells were used to detect calcium mobilization and release of inflammatory mediators in vitro. WT mice showed a severe local inflammatory response and contact dermatitis, whereas only slight inflammatory infiltration was observed in MUT mice. Thus, MRGPRX2 mediated the IU-induced activation of mast cells. However, histamine, a typical allergen, was not involved in this process. Tryptase expressed by mast cells was the major non-histaminergic inflammatory mediator of contact dermatitis. IU induced anaphylactic reaction via MRGPRX2 and further triggering non-histaminergic contact dermatitis, which explained why antihistamines are clinically ineffective against some chronic dermatitis.

scholarly journals Ibrexafungerp: A First-in-Class Oral Triterpenoid Glucan Synthase Inhibitor

2021 ◽  
Vol 7 (3) ◽  
pp. 163 ◽  
Author(s):  
Sabelle Jallow ◽  
Nelesh P. Govender
Keyword(s):  
Pathogenic Fungi ◽  
Candida Spp ◽  
Fungal Cell ◽  
Favourable Safety ◽  
Favourable Safety Profile ◽  
Synthase Inhibitor ◽  
Increased Activity ◽  
In Vitro Data

Ibrexafungerp (formerly SCY-078 or MK-3118) is a first-in-class triterpenoid antifungal or “fungerp” that inhibits biosynthesis of β-(1,3)-D-glucan in the fungal cell wall, a mechanism of action similar to that of echinocandins. Distinguishing characteristics of ibrexafungerp include oral bioavailability, a favourable safety profile, few drug–drug interactions, good tissue penetration, increased activity at low pH and activity against multi-drug resistant isolates including C. auris and C. glabrata. In vitro data has demonstrated broad and potent activity against Candida and Aspergillus species. Importantly, ibrexafungerp also has potent activity against azole-resistant isolates, including biofilm-forming Candida spp., and echinocandin-resistant isolates. It also has activity against the asci form of Pneumocystis spp., and other pathogenic fungi including some non-Candida yeasts and non-Aspergillus moulds. In vivo data have shown IBX to be effective for treatment of candidiasis and aspergillosis. Ibrexafungerp is effective for the treatment of acute vulvovaginal candidiasis in completed phase 3 clinical trials.

scholarly journals Integrin α6 mediates the drug resistance of acute lymphoblastic B-cell leukemia

Blood ◽  
2020 ◽  
Vol 136 (2) ◽  
pp. 210-223 ◽  
Author(s):  
Eun Ji Gang ◽  
Hye Na Kim ◽  
Yao-Te Hsieh ◽  
Yongsheng Ruan ◽  
Heather A. Ogana ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Kinase Inhibitor ◽  
Residual Disease ◽  
Lymphoblastic Leukemia ◽  
Underlying Mechanism ◽  
Conditional Knockout

Abstract Resistance to multimodal chemotherapy continues to limit the prognosis of acute lymphoblastic leukemia (ALL). This occurs in part through a process called adhesion-mediated drug resistance, which depends on ALL cell adhesion to the stroma through adhesion molecules, including integrins. Integrin α6 has been implicated in minimal residual disease in ALL and in the migration of ALL cells to the central nervous system. However, it has not been evaluated in the context of chemotherapeutic resistance. Here, we show that the anti-human α6-blocking Ab P5G10 induces apoptosis in primary ALL cells in vitro and sensitizes primary ALL cells to chemotherapy or tyrosine kinase inhibition in vitro and in vivo. We further analyzed the underlying mechanism of α6-associated apoptosis using a conditional knockout model of α6 in murine BCR-ABL1+ B-cell ALL cells and showed that α6-deficient ALL cells underwent apoptosis. In vivo deletion of α6 in combination with tyrosine kinase inhibitor (TKI) treatment was more effective in eradicating ALL than treatment with a TKI (nilotinib) alone. Proteomic analysis revealed that α6 deletion in murine ALL was associated with changes in Src signaling, including the upregulation of phosphorylated Lyn (pTyr507) and Fyn (pTyr530). Thus, our data support α6 as a novel therapeutic target for ALL.

scholarly journals Caenorhabditis elegans as an in vivo Model to Assess Amphetamine Tolerance

2021 ◽  
pp. 1-9
Author(s):  
Dayana Torres Valladares ◽  
Sirisha Kudumala ◽  
Murad Hossain ◽  
Lucia Carvelli
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Drugs Of Abuse ◽  
Genetic Model ◽  
In Vivo Model ◽  
C Elegans ◽  
Hyperactivity Disorder ◽  
In Vitro Data

Amphetamine is a potent psychostimulant also used to treat attention deficit/hyperactivity disorder and narcolepsy. In vivo and in vitro data have demonstrated that amphetamine increases the amount of extra synaptic dopamine by both inhibiting reuptake and promoting efflux of dopamine through the dopamine transporter. Previous studies have shown that chronic use of amphetamine causes tolerance to the drug. Thus, since the molecular mechanisms underlying tolerance to amphetamine are still unknown, an animal model to identify the neurochemical mechanisms associated with drug tolerance is greatly needed. Here we took advantage of a unique behavior caused by amphetamine in <i>Caenorhabditis elegans</i> to investigate whether this simple, but powerful, genetic model develops tolerance following repeated exposure to amphetamine. We found that at least 3 treatments with 0.5 mM amphetamine were necessary to see a reduction in the amphetamine-induced behavior and, thus, to promote tolerance. Moreover, we found that, after intervals of 60/90 minutes between treatments, animals were more likely to exhibit tolerance than animals that underwent 10-minute intervals between treatments. Taken together, our results show that <i>C. elegans</i> is a suitable system to study tolerance to drugs of abuse such as amphetamines.

scholarly journals Sirt1 deacetylates and stabilizes p62 to promote hepato-carcinogenesis

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Lifeng Feng ◽  
Miaoqin Chen ◽  
Yiling Li ◽  
Muchun Li ◽  
Shiman Hu ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Overall Survival ◽  
Cell Growth ◽  
Knockout Mice ◽  
Liver Tumors ◽  
Underlying Mechanism ◽  
Carcinoma Cells ◽  
Conditional Knockout

Abstractp62/SQSTM1 is frequently up-regulated in many cancers including hepatocellular carcinoma. Highly expressed p62 promotes hepato-carcinogenesis by activating many signaling pathways including Nrf2, mTORC1, and NFκB signaling. However, the underlying mechanism for p62 up-regulation in hepatocellular carcinoma remains largely unclear. Herein, we confirmed that p62 was up-regulated in hepatocellular carcinoma and its higher expression was associated with shorter overall survival in patients. The knockdown of p62 in hepatocellular carcinoma cells decreased cell growth in vitro and in vivo. Intriguingly, p62 protein stability could be reduced by its acetylation at lysine 295, which was regulated by deacetylase Sirt1 and acetyltransferase GCN5. Acetylated p62 increased its association with the E3 ligase Keap1, which facilitated its poly-ubiquitination-dependent proteasomal degradation. Moreover, Sirt1 was up-regulated to deacetylate and stabilize p62 in hepatocellular carcinoma. Additionally, Hepatocyte Sirt1 conditional knockout mice developed much fewer liver tumors after Diethynitrosamine treatment, which could be reversed by the re-introduction of exogenous p62. Taken together, Sirt1 deacetylates p62 at lysine 295 to disturb Keap1-mediated p62 poly-ubiquitination, thus up-regulating p62 expression to promote hepato-carcinogenesis. Therefore, targeting Sirt1 or p62 is a reasonable strategy for the treatment of hepatocellular carcinoma.

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