scholarly journals Impaired adaptation to repeated restraint and decreased response to cold in urocortin 1 knockout mice

2007 ◽  
Vol 293 (1) ◽  
pp. E259-E263 ◽  
Author(s):  
Alena A. Zalutskaya ◽  
Maya Arai ◽  
George S. Bounoutas ◽  
Abdul B. Abou-Samra
Keyword(s):  
Hpa Axis ◽  
Physiological Role ◽  
Corticotropin Releasing Factor ◽  
Cold Environment ◽  
Wild Type ◽  
Partial Adaptation ◽  
Urocortin 1 ◽  
Corticosterone Response ◽  
Males And Females

Urocortin 1 (UCN1) is a corticotropin-releasing factor (CRF)-like peptide whose role in stress is not well characterized. To study the physiological role of UCN1 in the response of the hypothalamic-pituitary-adrenal (HPA) axis to stress, we generated UCN1-knockout (KO) mice and examined their adaptation to repeated restraint and to cold environment. Wild-type (WT) and UCN1-KO animals were restrained hourly for 15 min from 9 AM to 2 PM, and blood samples were obtained for corticosterone measurement. WT animals adapted to repeated restraint with a decreased corticosterone response; the restraint-stimulated corticosterone levels fell from 215 ± 31 ng/ml in naïve animals to 142 ± 50 ng/ml in mice subjected to repeated restraint ( P < 0.01) and from 552 ± 98 to 314 ± 58 ng/ml ( P < 0.001) in males and females, respectively. Male UCN1-KO mice did not show any adaptation to repeated restraint; instead, restraint-stimulated corticosterone levels were increased from 274 ± 80 ng/ml in naïve animals to 480 ± 75 ng/ml in mice subjected to repeated restraint ( P < 0.001). Female UCN1-KO mice showed only a partial adaptation to repeated restraint, with a decrease in the restraint-stimulated corticosterone response from 631 ± 102 ng/ml in naïve animals to 467 ± 78 ng/ml in mice subjected to repeated restraint ( P < 0.01). In addition, UCN1-KO mice showed no corticosterone response to 2-h cold environment. These data demonstrate an important role for UCN1 in the HPA axis adaptation to repeated restraint and in the corticosterone response to a cold environment.

scholarly journals Bub1 mediates cell death in response to chromosome missegregation and acts to suppress spontaneous tumorigenesis

2007 ◽  
Vol 179 (2) ◽  
pp. 255-267 ◽  
Author(s):  
Karthik Jeganathan ◽  
Liviu Malureanu ◽  
Darren J. Baker ◽  
Susan C. Abraham ◽  
Jan M. van Deursen
Keyword(s):  
Cell Death ◽  
Chromosome Segregation ◽  
Physiological Role ◽  
Mitotic Checkpoint ◽  
Critical Threshold ◽  
Wild Type ◽  
Checkpoint Protein ◽  
Chromosome Missegregation ◽  
Mitotic Checkpoint Protein

The physiological role of the mitotic checkpoint protein Bub1 is unknown. To study this role, we generated a series of mutant mice with a gradient of reduced Bub1 expression using wild-type, hypomorphic, and knockout alleles. Bub1 hypomorphic mice are viable, fertile, and overtly normal despite weakened mitotic checkpoint activity and high percentages of aneuploid cells. Bub1 haploinsufficient mice, which have a milder reduction in Bub1 protein than Bub1 hypomorphic mice, also exhibit reduced checkpoint activity and increased aneuploidy, but to a lesser extent. Although cells from Bub1 hypomorphic and haploinsufficient mice have similar rates of chromosome missegregation, cell death after an aberrant separation decreases dramatically with declining Bub1 levels. Importantly, Bub1 hypomorphic mice are highly susceptible to spontaneous tumors, whereas Bub1 haploinsufficient mice are not. These findings demonstrate that loss of Bub1 below a critical threshold drives spontaneous tumorigenesis and suggest that in addition to ensuring proper chromosome segregation, Bub1 is important for mediating cell death when chromosomes missegregate.

scholarly journals Deletion of the rpoZ gene, encoding the ω subunit of RNA polymerase, results in pleiotropic surface-related phenotypes in Mycobacterium smegmatis

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1741-1750 ◽  
Author(s):  
Renjith Mathew ◽  
Raju Mukherjee ◽  
Radhakrishnan Balachandar ◽  
Dipankar Chatterji
Keyword(s):  
Rna Polymerase ◽  
Mycobacterium Smegmatis ◽  
Biofilm Formation ◽  
Physiological Role ◽  
Wild Type ◽  
Gene Encoding ◽  
Biofilm Growth ◽  
Mutant Bacterium ◽  
Sliding Motility

The ω subunit, the smallest subunit of bacterial RNA polymerase, is known to be involved in maintaining the conformation of the β′ subunit and aiding its recruitment to the rest of the core enzyme assembly in Escherichia coli. It has recently been shown in Mycobacterium smegmatis, by creating a deletion mutation of the rpoZ gene encoding ω, that the physiological role of the ω subunit also includes providing physical protection to β′. Interestingly, the mutant had altered colony morphology. This paper demonstrates that the mutant mycobacterium has pleiotropic phenotypes including reduced sliding motility and defective biofilm formation. Analysis of the spatial arrangement of biofilms by electron microscopy suggests that the altered phenotype of the mutant arises from a deficiency in generation of extracellular matrix. Complementation of the mutant strain with a copy of the wild-type rpoZ gene integrated in the bacterial chromosome restored both sliding motility and biofilm formation to the wild-type state, unequivocally proving the role of ω in the characteristics observed for the mutant bacterium. Analysis of the cell wall composition demonstrated that the mutant bacterium had an identical glycopeptidolipid profile to the wild-type, but failed to synthesize the short-chain mycolic acids characteristic of biofilm growth in M. smegmatis.

scholarly journals The Centrosomal, Putative Tumor Suppressor Protein TACC2 Is Dispensable for Normal Development, and Deficiency Does Not Lead to Cancer

2004 ◽  
Vol 24 (14) ◽  
pp. 6403-6409 ◽  
Author(s):  
Michael M. Schuendeln ◽  
Roland P. Piekorz ◽  
Christian Wichmann ◽  
Youngsoo Lee ◽  
Peter J. McKinnon ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Cell Cycle Progression ◽  
Tumor Development ◽  
Coiled Coil ◽  
Physiological Role ◽  
Tumor Suppressor Protein ◽  
Wild Type ◽  
Mouse Development

ABSTRACT TACC2 is a member of the transforming acidic coiled-coil-containing protein family and is associated with the centrosome-spindle apparatus during cell cycling. In vivo, the TACC2 gene is expressed in various splice forms predominantly in postmitotic tissues, including heart, muscle, kidney, and brain. Studies of human breast cancer samples and cell lines suggest a putative role of TACC2 as a tumor suppressor protein. To analyze the physiological role of TACC2, we generated mice lacking TACC2. TACC2-deficient mice are viable, develop normally, are fertile, and lack phenotypic changes compared to wild-type mice. Furthermore, TACC2 deficiency does not lead to an increased incidence of tumor development. Finally, in TACC2-deficient embryonic fibroblasts, proliferation and cell cycle progression as well as centrosome numbers are comparable to those in wild-type cells. Therefore, TACC2 is not required, nonredundantly, for mouse development and normal cell proliferation and is not a tumor suppressor protein.

Role of α2-macroglobulin in fever and cytokine responses induced by lipopolysaccharide in mice

2002 ◽  
Vol 283 (1) ◽  
pp. R218-R226 ◽  
Author(s):  
Alexander V. Gourine ◽  
Valery N. Gourine ◽  
Yohannes Tesfaigzi ◽  
Nathalie Caluwaerts ◽  
Fred Van Leuven ◽  
...  
Keyword(s):  
Mrna Level ◽  
Physiological Role ◽  
Mrna Levels ◽  
Wild Type ◽  
Cytokine Responses ◽  
Α2 Macroglobulin ◽  
Tnf Α ◽  
Factor Α ◽  
Necrosis Factor

α2-Macroglobulin (α2M) is not only a proteinase inhibitor in mammals, but it is also a specific cytokine carrier that binds pro- and anti-inflammatory cytokines implicated in fever, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). To define the role of α2M in regulation of febrile and cytokine responses, wild-type mice and mice deficient in α2M (α2M −/−) were injected with lipopolysaccharide (LPS). Changes in body temperature as well as plasma levels of IL-1β, IL-6, and TNF-α and hepatic TNF-α mRNA level during fever in α2M −/− mice were compared with those in wild-type control mice. The α2M −/− mice developed a short-term markedly attenuated (ANOVA, P < 0.05) fever in response to LPS (2.5 mg/kg ip) compared with the wild-type mice. At 1.5 h after injection of LPS, the plasma concentration of TNF-α, but not IL-1β or IL-6, was significantly lower (by 58%) in the α2M −/− mice compared with their wild-type controls (ANOVA, P < 0.05). There was no difference in hepatic TNF-α mRNA levels between α2M −/− and wild-type mice 1.5 h after injection of LPS. These data support the hypotheses that 1) α2M is important for the normal development of LPS-induced fever and 2) a putative mechanism of α2M involvement in fever is through the inhibition of TNF-α clearance. These findings indicate a novel physiological role for α2M.

scholarly journals Altered Responses to Cold Environment in Urocortin 1 and Corticotropin-Releasing Factor Deficient Mice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Bayan Chaker ◽  
Tareq A. Samra ◽  
Nabanita S. Datta ◽  
Abdul B. Abou-Samra
Keyword(s):  
Protein Metabolism ◽  
Core Body Temperature ◽  
Corticotropin Releasing Factor ◽  
Dexamethasone Treatment ◽  
Male And Female ◽  
Dramatic Decline ◽  
Urocortin 1 ◽  
Core Body ◽  
Deficient Mice

We examined core body temperature (CBT) of urocortin 1 (UCN1) and corticotropin releasing factor (CRF) knockout (KO) mice exposed to 4°C for 2 h. UCN1KO mice showed higher average CBT during cold exposure as compared to WT. The CBT of male and female WT mice dropped significantly to 34.1 ± 2.4 and 34.9 ± 3.1 C at 4°C, respectively. In contrast, the CBT of male and female UCN1KO mice dropped only slightly after 2 h at 4°C to 36.8 ± 0.7 and 38.1 ± 0.5 C, respectively. WT female and male UCN1KO mice showed significant acclimatization to cold; however, female UCN1KO mice did not show such a significant acclimatization. CRFKO mice showed a dramatic decline in CBT from 38.2 ±  0.4 at 22°C to 26.1 ± 9.8 at 4°C for 2 h. The CRF/UCN1 double KO (dKO) mice dropped their CBT to 32.5 ± 4.0 after 2 h exposure to 4°C. Dexamethasone treatment prevented the decline in CBT of the CRFKO and the dKO mice. Taken together, the data suggest a novel role for UCN1 in thermoregulation. The role of CRF is likely secondary to adrenal glucocorticoids, which have an important regulatory role on carbohydrate, fat, and protein metabolism.

scholarly journals Targeted disruption of G protein-coupled bile acid receptor 1 (Gpbar1/M-Bar) in mice

2006 ◽  
Vol 191 (1) ◽  
pp. 197-205 ◽  
Author(s):  
Takaharu Maruyama ◽  
Kenichi Tanaka ◽  
Jun Suzuki ◽  
Hiroyuki Miyoshi ◽  
Naomoto Harada ◽  
...  
Keyword(s):  
Bile Acid ◽  
G Protein ◽  
Physiological Role ◽  
Wild Type ◽  
Fat Accumulation ◽  
Acid Receptor ◽  
Bile Acid Receptor ◽  
The Impact ◽  
G Protein Coupled

G protein-coupled bile acid receptor 1 (Gpbar1/M-Bar) is a novel G protein-coupled receptor for bile acid. Tissue distribution and cell-type specificity of Gpbar1 mRNA suggest a potential role for the receptor in the endocrine system; however, the precise physiological role of Gpbar1 still remains to be elucidated. To investigate the role of Gpbar1 in vivo, the Gpbar1 gene was disrupted in mice. In homozygous mice, total bile acid pool size was significantly decreased by 21–25% compared with that of the wild-type mice, suggesting that Gpbar1 contributes to bile acid homeostasis. In order to assess the impact of Gpbar1 deficiency in bile acid homeostasis more precisely, Gpbar1 homozygous mice were fed a high-fat diet for 2 months. As a result, female Gpbar1 homozygous mice showed significant fat accumulation with body weight gain compared with that of the wild-type mice. These findings were also observed in heterozygous mice to the same extent. Although the precise mechanism for fat accumulation in female Gpbar1 homozygous mice remains to be addressed, these data indicate that Gpbar1 is a potential new player in energy homeostasis. Thus, Gpbar1-deficient mice are useful in elucidating new physiological roles for Gpbar1.

scholarly journals Functional role of respiratory supercomplexes in mice: segmentation of the Qpool and SCAF1

2019 ◽  
Author(s):  
Enrique Calvo ◽  
Sara Cogliati ◽  
Pablo Hernansanz-Agustín ◽  
Marta Loureiro-López ◽  
Adela Guarás ◽  
...  
Keyword(s):  
Quantitative Data ◽  
Functional Role ◽  
Physiological Role ◽  
Oxidative Capacity ◽  
Wild Type ◽  
Knock Out ◽  
Transport Chain ◽  
Native Gel ◽  
Blue Native

SummaryMitochondrial respiratory complexes assemble into different forms of supercomplexes (SC). In particular, SC III2+IV require the SCAF1 protein. However, the structural role of this factor in the formation of the respirasome (I+III2+IV) and the physiological role of SCs are controversial. Here, we study C57BL/6J mice harbouring either non-functional SCAF1, the full knock-out for SCAF1 or the wild-type version of the protein and found a growth and exercise phenotype due to the lack of functional SCAF1. By combining quantitative data-independent proteomics, high resolution 2D Blue Native Gel Electrophoresis and functional analysis of enriched respirasome fractions, we show that SCAF1 confers structural attachment between III2 and IV within the respirasome, increases NADH-dependent respiration and reduces ROS production. Furthermore, through the expression of AOX in cells and mice we confirm that CI-CIII superassembly segments the CoQ in two pools and modulates CI-NADH oxidative capacity. These data demonstrate that SC assembly, regulated by SCAF1, modulates the functionality of the electron transport chain.

scholarly journals Visualizing endogenous opioid receptors in living neurons using ligand-directed chemistry

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Seksiri Arttamangkul ◽  
Andrew Plazek ◽  
Emily J Platt ◽  
Haihong Jin ◽  
Thomas F Murray ◽  
...  
Keyword(s):  
Opioid Receptors ◽  
Physiological Role ◽  
Loss Of Function ◽  
Wild Type ◽  
Endogenous Opioid ◽  
Covalently Linked ◽  
Living Tissues ◽  
Living Neurons ◽  
Post Hoc

Identifying neurons that have functional opioid receptors is fundamental for the understanding of the cellular, synaptic and systems actions of opioids. Current techniques are limited to post hoc analyses of fixed tissues. Here we developed a fluorescent probe, naltrexamine-acylimidazole (NAI), to label opioid receptors based on a chemical approach termed ‘traceless affinity labeling’. In this approach, a high affinity antagonist naltrexamine is used as the guide molecule for a transferring reaction of acylimidazole at the receptor. This reaction generates a fluorescent dye covalently linked to the receptor while naltrexamine is liberated and leaves the binding site. The labeling induced by this reagent allowed visualization of opioid-sensitive neurons in rat and mouse brains without loss of function of the fluorescently labeled receptors. The ability to locate endogenous receptors in living tissues will aid considerably in establishing the distribution and physiological role of opioid receptors in the CNS of wild type animals.

scholarly journals Estrogen Receptor (ER)-β Reduces ERα-Regulated Gene Transcription, Supporting a “Ying Yang” Relationship between ERα and ERβ in Mice

2003 ◽  
Vol 17 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Marie K. Lindberg ◽  
Sofia Movérare ◽  
Stanko Skrtic ◽  
Hui Gao ◽  
Karin Dahlman-Wright ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Gene Transcription ◽  
Physiological Role ◽  
Estrogen Receptor Α ◽  
Mrna Levels ◽  
Wild Type ◽  
Ovariectomized Mice ◽  
Adult Bone

Abstract Estrogen is of importance for the regulation of adult bone metabolism. The aim of the present study was to determine the role of estrogen receptor-β (ERβ) in vivo on global estrogen-regulated transcriptional activity in bone. The effect of estrogen in bone of ovariectomized mice was determined using microarray analysis including 9400 genes. Most of the genes (95% = 240 genes) that were increased by estrogen in wild-type (WT) mice were also increased by estrogen in ERβ-inactivated mice. Interestingly, the average stimulatory effect of estrogen on the mRNA levels of these genes was 85% higher in ERβ-inactivated than in WT mice, demonstrating that ERβ reduces estrogen receptor-α (ERα)-regulated gene transcription in bone. The average stimulatory effect of estrogen on estrogen-regulated bone genes in ERα-inactivated mice was intermediate between that seen in WT and ERαβ double-inactivated mice. Thus, ERβ inhibits ERα-mediated gene transcription in the presence of ERα, whereas, in the absence of ERα, it can partially replace ERα. In conclusion, our in vivo data indicate that an important physiological role of ERβ is to modulate ERα-mediated gene transcription supporting a “Ying Yang” relationship between ERα and ERβ in mice.

scholarly journals Dynein Intermediate Chain Mediated Dynein–Dynactin Interaction Is Required for Interphase Microtubule Organization and Centrosome Replication and Separation inDictyostelium

1999 ◽  
Vol 147 (6) ◽  
pp. 1261-1274 ◽  
Author(s):  
Shuo Ma ◽  
Leda Triviños-Lagos ◽  
Ralph Gräf ◽  
Rex L. Chisholm
Keyword(s):  
Heavy Chain ◽  
Physiological Role ◽  
Cytoplasmic Dynein ◽  
Wild Type ◽  
Microtubule Organization ◽  
Dynein Intermediate Chain ◽  
Organizing Center ◽  
Intermediate Chain

Cytoplasmic dynein intermediate chain (IC) mediates dynein–dynactin interaction in vitro (Karki, S., and E.L. Holzbaur. 1995. J. Biol. Chem. 270:28806–28811; Vaughan, K.T., and R.B. Vallee. 1995. J. Cell Biol. 131:1507–1516). To investigate the physiological role of IC and dynein–dynactin interaction, we expressed IC truncations in wild-type Dictyostelium cells. ICΔC associated with dynactin but not with dynein heavy chain, whereas ICΔN truncations bound to dynein but bound dynactin poorly. Both mutations resulted in abnormal localization to the Golgi complex, confirming dynein function was disrupted. Striking disorganization of interphase microtubule (MT) networks was observed when mutant expression was induced. In a majority of cells, the MT networks collapsed into large bundles. We also observed cells with multiple cytoplasmic asters and MTs lacking an organizing center. These cells accumulated abnormal DNA content, suggesting a defect in mitosis. Striking defects in centrosome morphology were also observed in IC mutants, mostly larger than normal centrosomes. Ultrastructural analysis of centrosomes in IC mutants showed interphase accumulation of large centrosomes typical of prophase as well as unusually paired centrosomes, suggesting defects in centrosome replication and separation. These results suggest that dynactin-mediated cytoplasmic dynein function is required for the proper organization of interphase MT network as well as centrosome replication and separation in Dictyostelium.

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