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1.
Hum Genet ; 136(3): 297-305, 2017 03.
Article in English | MEDLINE | ID: mdl-28124119

ABSTRACT

Chromatin remodeling is a complex process shaping the nucleosome landscape, thereby regulating the accessibility of transcription factors to regulatory regions of target genes and ultimately managing gene expression. The SWI/SNF (switch/sucrose nonfermentable) complex remodels the nucleosome landscape in an ATP-dependent manner and is divided into the two major subclasses Brahma-associated factor (BAF) and Polybromo Brahma-associated factor (PBAF) complex. Somatic mutations in subunits of the SWI/SNF complex have been associated with different cancers, while germline mutations have been associated with autism spectrum disorder and the neurodevelopmental disorders Coffin-Siris (CSS) and Nicolaides-Baraitser syndromes (NCBRS). CSS is characterized by intellectual disability (ID), coarsening of the face and hypoplasia or absence of the fifth finger- and/or toenails. So far, variants in five of the SWI/SNF subunit-encoding genes ARID1B, SMARCA4, SMARCB1, ARID1A, and SMARCE1 as well as variants in the transcription factor-encoding gene SOX11 have been identified in CSS-affected individuals. ARID2 is a member of the PBAF subcomplex, which until recently had not been linked to any neurodevelopmental phenotypes. In 2015, mutations in the ARID2 gene were associated with intellectual disability. In this study, we report on two individuals with private de novo ARID2 frameshift mutations. Both individuals present with a CSS-like phenotype including ID, coarsening of facial features, other recognizable facial dysmorphisms and hypoplasia of the fifth toenails. Hence, this study identifies mutations in the ARID2 gene as a novel and rare cause for a CSS-like phenotype and enlarges the list of CSS-like genes.


Subject(s)
Abnormalities, Multiple/genetics , Face/abnormalities , Frameshift Mutation , Hand Deformities, Congenital/genetics , Heterozygote , Intellectual Disability/genetics , Micrognathism/genetics , Neck/abnormalities , Phenotype , Transcription Factors/genetics , Humans , Infant , Male
2.
Hum Genet ; 136(2): 179-192, 2017 02.
Article in English | MEDLINE | ID: mdl-27848077

ABSTRACT

The ubiquitin pathway is an enzymatic cascade including activating E1, conjugating E2, and ligating E3 enzymes, which governs protein degradation and sorting. It is crucial for many physiological processes. Compromised function of members of the ubiquitin pathway leads to a wide range of human diseases, such as cancer, neurodegenerative diseases, and neurodevelopmental disorders. Mutations in the thyroid hormone receptor interactor 12 (TRIP12) gene (OMIM 604506), which encodes an E3 ligase in the ubiquitin pathway, have been associated with autism spectrum disorder (ASD). In addition to autistic features, TRIP12 mutation carriers showed intellectual disability (ID). More recently, TRIP12 was postulated as a novel candidate gene for intellectual disability in a meta-analysis of published ID cohorts. However, detailed clinical information characterizing the phenotype of these individuals was not provided. In this study, we present seven novel individuals with private TRIP12 mutations including two splice site mutations, one nonsense mutation, three missense mutations, and one translocation case with a breakpoint in intron 1 of the TRIP12 gene and clinically review four previously published cases. The TRIP12 mutation-positive individuals presented with mild to moderate ID (10/11) or learning disability [intelligence quotient (IQ) 76 in one individual], ASD (8/11) and some of them with unspecific craniofacial dysmorphism and other anomalies. In this study, we provide detailed clinical information of 11 TRIP12 mutation-positive individuals and thereby expand the clinical spectrum of the TRIP12 gene in non-syndromic intellectual disability with or without ASD.


Subject(s)
Autistic Disorder/genetics , Carrier Proteins/genetics , Genetic Variation , Intellectual Disability/genetics , Ubiquitin-Protein Ligases/genetics , Adolescent , Autistic Disorder/diagnosis , Base Sequence , Child , Cohort Studies , Female , Genome, Human , Humans , Intellectual Disability/diagnosis , Karyotyping , Male , Mutation, Missense , Phenotype , Proteolysis , RNA Splicing , Sequence Analysis, DNA
3.
Handchir Mikrochir Plast Chir ; 46(5): 271-7, 2014 Oct.
Article in German | MEDLINE | ID: mdl-25290269

ABSTRACT

The present paper describes the indication and application of an arthroscopically assisted osteosynthesis for distal radius fractures. Visualisation of articular incongruency is emphasised with special regard to articular fracture fragment reduction. In addition to that, classification of soft tissue injuries and treatment options are discussed. The final clinical and radiological results of 17 patients are presented: DASH and PRWE averaged 4.9 and 6.0 respectively. Active range of motion measured 123° for flexion/extension, 51° for radial and ulnar deviation and 163° for pronosupination, which is 87%, 98% and 97%, respectively, compared with the opposite wrist. Radial inclination at final follow-up was 23°, palmar tilt measured 6° and ulnar variance averaged -1.2 mm. The scapholunate gap at follow-up was 1.6 mm, and the scapholunate angle measured 57°.


Subject(s)
Arthroscopy/methods , Fracture Fixation, Internal/methods , Intra-Articular Fractures/surgery , Joint Dislocations/surgery , Ligaments, Articular/surgery , Radius Fractures/surgery , Wrist Injuries/surgery , Carpal Joints/diagnostic imaging , Carpal Joints/injuries , Carpal Joints/surgery , Female , Fracture Healing/physiology , Humans , Intra-Articular Fractures/diagnostic imaging , Joint Dislocations/diagnostic imaging , Ligaments, Articular/diagnostic imaging , Ligaments, Articular/injuries , Postoperative Complications/diagnostic imaging , Radius Fractures/diagnostic imaging , Range of Motion, Articular/physiology , Tomography, X-Ray Computed , Wrist Injuries/diagnostic imaging , Young Adult
4.
Acta Diabetol ; 51(2): 211-8, 2014 Apr.
Article in English | MEDLINE | ID: mdl-23771613

ABSTRACT

Vasoregression characterizes diabetic retinopathy in animal models and in humans. We have recently demonstrated that vasoregression is earlier initiated in a rat model of ciliopathy-induced retinal neurodegeneration (TGR rat). The aim was to assess the balance between vasoregressive effects of chronic hyperglycemia and photoreceptor degeneration on adult vascular remodelling. The retinas were analyzed at 4 and 9 months after streptozotocin-induced diabetes. Neurodegeneration was determined by quantitation of cell numbers and retinal layer thickness. Vasoregression was assessed by quantitative retinal morphometry in retinal digest preparations. Retinal VEGF levels were measured by ELISA. Glial activation, expression and location of HSP27 and phosphorylated HSP27 were evaluated by immunofluorescence staining. Unexpectedly, the numbers of acellular capillaries were reduced at both time points and led to fewer intraretinal microvascular abnormalities in late stage diabetic TGR. Concomitantly, inner nuclear layers (INLs) in diabetic TGR rats were protected from cell loss at both time points. Consequently, glial activation was reduced, but VEGF level was increased in diabetic TGR retinas. Expressions of HSP27 were upregulated in glia cells in the preserved INL of diabetic TGR. Chronic hyperglycemia preserves the microvasculature in the retinal model of neurodegeneration. Cell preservation in the retinal INL was associated with protective gene regulation. Together, these data indicate that diabetes can induce vasoprotection, in which retinal glia can play a particular role.


Subject(s)
Diabetes Mellitus, Experimental/pathology , Diabetic Retinopathy/blood , Hyperglycemia/metabolism , Retinal Degeneration/blood , Vascular Diseases/blood , Animals , Diabetes Mellitus, Experimental/blood , Female , HSP27 Heat-Shock Proteins/blood , Histocytochemistry , Humans , Microscopy, Confocal , Microscopy, Fluorescence , Neuroglia/pathology , Random Allocation , Rats , Rats, Transgenic , Vascular Diseases/pathology , Vascular Endothelial Growth Factor A/blood
5.
Zoonoses Public Health ; 60(8): 539-42, 2013 Dec.
Article in English | MEDLINE | ID: mdl-23280311

ABSTRACT

In 2010, two independent cases of cutaneous diphtheria caused by toxigenic C. ulcerans were identified in Germany. Both patients had intense occupational contact with pigs. Diagnostic work-up comprising biochemical differentiation, rpoB sequencing, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) analysis, real-time tox PCR and Elek test as well as public health measures including an intensified source tracing involving 83 asymptomatic pigs of an associated pig farm are presented.


Subject(s)
Corynebacterium/isolation & purification , Diphtheria/diagnosis , Occupational Exposure , Skin Diseases, Bacterial/diagnosis , Swine Diseases/microbiology , Animals , Anti-Bacterial Agents/therapeutic use , Bacterial Proteins/genetics , Carrier State/epidemiology , Carrier State/microbiology , Carrier State/veterinary , Diphtheria/drug therapy , Diphtheria/microbiology , Erythromycin/therapeutic use , Female , Germany , Humans , Male , Middle Aged , Prevalence , Real-Time Polymerase Chain Reaction , Sequence Analysis, DNA , Skin/microbiology , Skin Diseases, Bacterial/drug therapy , Skin Diseases, Bacterial/microbiology , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Sus scrofa , Swine , Swine Diseases/epidemiology , Swine Diseases/transmission
6.
Dtsch Med Wochenschr ; 137(43): 2229-31, 2012 Oct.
Article in German | MEDLINE | ID: mdl-23076671

ABSTRACT

Pneumocystsis jirovecii is a peculiar fungus for a variety of reasons. This opportunistic pathogen multiplies in humans only under certain conditions; a defect in the T-cell defense system creates a predisposition to this infection. In 2010 a data survey (IFT as well as PCR) from a few laboratories in Germany revealed 412 positive individuals. Even if only a few patients test positive for the colonization stage of this pathogen, the sheer number of individuals testing positive for other stages of infection indicate that the incidence of pneumocystosis in immunocompromised patients in Germany is underestimated.


Subject(s)
Health Surveys , Pneumocystis carinii , Pneumonia, Pneumocystis/epidemiology , Rare Diseases , AIDS-Related Opportunistic Infections/diagnosis , AIDS-Related Opportunistic Infections/epidemiology , Child, Preschool , Cross-Sectional Studies , Germany , Humans , Incidence , Infant , Infant, Newborn , Infant, Premature, Diseases/diagnosis , Infant, Premature, Diseases/epidemiology , Middle Aged , Opportunistic Infections/diagnosis , Opportunistic Infections/epidemiology , Pneumonia, Pneumocystis/diagnosis , Polymerase Chain Reaction
7.
Praxis (Bern 1994) ; 101(7): 483-7, 2012 Mar 28.
Article in German | MEDLINE | ID: mdl-22454311

ABSTRACT

The differential diagnosis of eosinophilia is broad and constitutes a major challenge for both, the general practitioner and the hematologist. Whereas in developing countries secondary eosinophilia is commonly caused by parasitic infections, in Western and European countries eosinophilia is more often associated with atopic diseases or drug-related. This case-report presents an asymptomatic patient with marked persisting eosinophilia caused by Strongyloidiasis in whom parasitic stool examinations were repeatedly negative and infection could only be established by serologic testing.


Subject(s)
Eosinophilia/etiology , Strongyloidiasis/diagnosis , Adult , Algorithms , Chronic Disease , Diagnosis, Differential , Eosinophils , Humans , Leukocyte Count , Male
8.
Injury ; 38(10): 1170-6, 2007 Oct.
Article in English | MEDLINE | ID: mdl-16979170

ABSTRACT

The classic ilioinguinal approach is a gold standard in acetabular surgery. We developed a modification, a minimally invasive method that entails a median lower abdominal approach with extraperitoneal dissection and exposure of the pubic symphysis. The second incision is lateral, next to the iliac crest. This allows an easy, safe and quick exposure of the anterior iliac ring as well as easy access to the posterior column and wall towards the sacroiliac joint. The iliac vessels and nerves are thereby protected, and no preparation of neurovascular structures is required. The technique was applied in 23 clinical cases and compared with the classic ilioinguinal approach in 9 similar cases over the same period.


Subject(s)
Acetabulum/injuries , Acetabulum/surgery , Fracture Fixation, Internal/methods , Fractures, Bone/surgery , Adult , Aged , Aged, 80 and over , Female , Humans , Ilium/surgery , Inguinal Canal/surgery , Male , Middle Aged , Minimally Invasive Surgical Procedures/methods , Treatment Outcome
9.
Praxis (Bern 1994) ; 96(50): 1997-2001, 2007 Dec 12.
Article in German | MEDLINE | ID: mdl-18179107

ABSTRACT

WHO describes palliative care as the approach to patients with incurable illnesses. It covers identification and treatment of pain and other physical symptoms, psychological, social, and spiritual difficulties. A tight cooperation between the family doctor, the hospital (medical clinic with the subspecialists, geriatric and palliative care centre), the Spitex, the social, psychological, and the pastoral workers is needed. The family doctor needs to know much about medication and specific interventions in order to alleviate the patients' symptoms such as pain, breathlessness, cough, difficulties to swallow, nausea, vomiting, constipation, ileus, nutritional problems, fear, depression, and fatigue. The specific interventions may include irradiation, stenting of bile ducts, oesophagus or colon, hormonal treatment etc. A very important aspect is pain control and the correct handling of non-opioid analgesics, opioids, and co-analgesics. The terminal phase at home is a special challenge for the family doctor acting as a palliative physician.


Subject(s)
Neoplasms/therapy , Palliative Care/methods , Analgesics/therapeutic use , Analgesics, Opioid/adverse effects , Analgesics, Opioid/therapeutic use , Drug Therapy, Combination , Family Practice , Humans , Neoplasms/physiopathology , Pain/drug therapy , Patient Care Team , Practice Guidelines as Topic , Terminal Care/methods
10.
Naunyn Schmiedebergs Arch Pharmacol ; 373(5): 333-41, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16896804

ABSTRACT

According to cDNA sequence homologies, Gef10 is related to the Rho-specific guanine nucleotide exchange factors GrinchGEF and p164-RhoGEF. Like these GEFs, Gef10 exhibits only weak homology to known pleckstrin homology domains, but contains a putative WD40-like domain. As detected by RT-PCR, Gef10 is transcribed in at least two splice variants in different human tissues. Although the Gef10 sequence contains two putative transmembrane segments, recombinantly expressed Gef10 displays a cytosolic localisation. As detected by guanine nucleotide exchange activity assay, precipitation assay of GTP-bound Rho proteins and serum response element dependent gene transcription Gef10 activates RhoA-C, but not Rac1 or Cdc42. In the reporter gene assay, Gef10 preferentially activated RhoB. When expressed in NIH3T3 cells, Gef10 induced actin stress fibre, but not lamellipodia or filopodia formation. We conclude that Gef10 is the third member of a Rho-specific GEF family with unusual protein architecture.


Subject(s)
Guanine Nucleotide Exchange Factors/metabolism , Animals , Cell Line , Cloning, Molecular , Guanine Nucleotide Exchange Factors/biosynthesis , Guanine Nucleotide Exchange Factors/genetics , Humans , Mice , Protein Isoforms/biosynthesis , Protein Isoforms/genetics , Protein Isoforms/metabolism , Rho Guanine Nucleotide Exchange Factors , Stress Fibers/physiology , rho GTP-Binding Proteins/metabolism
11.
Praxis (Bern 1994) ; 94(7): 233-7, 2005 Feb 16.
Article in German | MEDLINE | ID: mdl-15773139

ABSTRACT

In order to competently advise people who are planning to travel abroad the doctor needs information both about the planned journey (the mode of travel, the itinerary, the time of the trip) and about possible preexisting health problems. The area where the traveller intends to stay determines the specific risk of endemic diseases such as malaria, dengue-fever, yellow-fever etc. The recommendations for prophylaxis of malaria and for the different vaccinations are constantly modified and can be attained from the internet. Pre-existing health hazards such as cardiovascular diseases, diabetes mellitus, HIV-infection need to be assessed. Special consideration should be taken for pregnant women. The traveller returning from an endemic malarious area who feels ill or is febrile is a medical emergency and must be assessed for the possibility of having malaria since nontreated malaria in non-immune people has a very high mortality rate. Diarrhea is a common problem but is rarely dangerous. Long standing or bloody diarrhea, however, calls for a thorough search for the responsible pathogen. Healthy return travellers do not need a check-up examination because there are virtually no consequences for treatment.


Subject(s)
Travel , Diarrhea/drug therapy , Diarrhea/etiology , Diarrhea/prevention & control , Hepatitis A Vaccines/administration & dosage , Hepatitis B Vaccines/administration & dosage , Humans , Immunization , Malaria/prevention & control , Risk Factors , Time Factors
12.
Praxis (Bern 1994) ; 91(31-32): 1241-5, 2002 Jul 31.
Article in German | MEDLINE | ID: mdl-12212344

ABSTRACT

Legionellosis is a relatively rare disease characterized by an often prolonged and complicated course even in immunocompetent patients. Its diagnosis is mandatory for therapeutic and epidemiologic reasons. At the Kantonsspital Chur between 1998 and 2001, 6 cases of legionellosis have been observed: four of them were travel-associated and one concerned a local hotel employee. Due to the increasing international mobility epidemiologic investigations for the localization and elimination of the sources of infection are very difficult. A european task force, the European Working Group for Legionella Infections (EWGLI/www.ewgli.org) is addressing this problem. It is a matter of debate to what extent the public should be informed about sources of legionellosis (so called legionella hotels).


Subject(s)
Legionnaires' Disease/epidemiology , Travel/statistics & numerical data , Adult , Aged , Community-Acquired Infections/epidemiology , Community-Acquired Infections/transmission , Cross Infection/epidemiology , Cross Infection/transmission , Cross-Sectional Studies , Female , Humans , Incidence , Legionnaires' Disease/transmission , Male , Middle Aged , Risk , Switzerland/epidemiology
13.
Ther Umsch ; 59(3): 105-9, 2002 Mar.
Article in German | MEDLINE | ID: mdl-11975397

ABSTRACT

Renal insufficiency is a fairly frequent problem, whether it is due to a kidney disease per se or to an extrarenal disease or to a combination of both. In contrast, chronic renal failure requiring renal replacement therapy is a rare condition in the practitioner's office. Considering this, the question is important to the practitioner, when in the course of the disease there is need for referral to a nephrologist. In this context two main questions have to be raised: first, is the disease curable or at least partially reversible (depending on the etiology of the renal disease) and second, when has the time arrived to prepare the patient for a renal replacement therapy. The cooperation with a nephrologist has to be sought early enough in order to choose the best moment for these actions. There are several European and American studies dealing with these problems and proving the benefit of a timely referral and a timely start of treatment. We extract some of the relevant data considering own data collected at the University Hospital of Berne (Inselspital), Switzerland.


Subject(s)
Kidney Failure, Chronic/therapy , Renal Replacement Therapy , Acute Kidney Injury/complications , Drug-Related Side Effects and Adverse Reactions , Hospitalization , Humans , Kidney Failure, Chronic/chemically induced , Kidney Failure, Chronic/diagnosis , Kidney Failure, Chronic/mortality , Kidney Function Tests , Middle Aged , Nephrology , Peritoneal Dialysis , Referral and Consultation , Renal Dialysis , Retrospective Studies , Risk Factors , Time Factors
14.
Eur J Clin Microbiol Infect Dis ; 21(12): 880-3, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12525924

ABSTRACT

The genodiversity of Staphylococcus aureus isolates from the Nottingham region of the United Kingdom was compared with isolates from the Freiburg region of Germany. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) isolates was higher in Nottingham than in Freiburg. In patients from Nottingham hospitals, 80% of MRSA isolates were classical epidemic MRSA-15, but genotypic variants of epidemic MRSA-15 comprised 72% of isolates from Nottingham community-based patients. In contrast, MRSA isolates from Freiburg showed greater diversity, but 47% and 23% of isolates, respectively, belonged to two predominant MRSA genotypes found in isolates from both hospitalised and community-based patients. The results suggest that genodiversity becomes increasingly more confined in settings with a higher frequency and longer duration of MRSA prevalence.


Subject(s)
Genetic Variation/genetics , Methicillin Resistance/genetics , Methicillin/pharmacology , Staphylococcal Infections/microbiology , Staphylococcus aureus/drug effects , Staphylococcus aureus/genetics , Germany/epidemiology , Humans , Penicillins/pharmacology , Prevalence , Staphylococcal Infections/epidemiology , Staphylococcus aureus/isolation & purification , Staphylococcus aureus/physiology , United Kingdom/epidemiology
15.
Pflugers Arch ; 442(6): 920-7, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11680626

ABSTRACT

Release of bacterial endotoxin and cytokines induce cardiac failure during sepsis. We investigated the direct effects of E. coli endotoxin (lipopolysaccharide, LPS) and cytokines induced by LPS on the cardiac myocyte gene program. For in vivo-experiments adult Wistar rats were given 600 microg/day LPS i.v. for 24 h or 7 days. In addition, cultured adult rat cardiac myocytes were treated with LPS, interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNFalpha), interferon-gamma (IFNgamma) or IL-6 for 24 h. mRNA expression was evaluated for cardiac-alpha-actin (cAct), skeletal-alpha-actin (skAct), beta- and alpha-myosin heavy chain (MHC). LPS induced betaMHC-mRNA 3.6-fold and repressed alphaMHC 2.7-fold and cAct 2.5-fold after 24 h in vivo. Up-regulation of betaMHC (3-fold) and repression of cAct (2.5-fold) were still observed after 7 days LPS infusion, whereas alphaMHC-mRNA levels had returned to normal. At the protein level, increased expression of betaMHC by LPS treatment occurred already after 24 h and was maintained thereafter. LPS had no influence on skAct-mRNA. Similar changes in contractile protein mRNA expression were observed in LPS-treated cardiomyocytes in culture, whereas the tested cytokines either activated (IL-1beta, IFNgamma) or repressed (TNFalpha, IL-6) both MHC-isoforms and cAct. In conclusion, LPS and proinflammatory cytokines induce changes in contractile protein expression that may contribute to the acute heart failure observed during endotoxaemia.


Subject(s)
Contractile Proteins/genetics , Cytokines/pharmacology , Lipopolysaccharides/pharmacology , Myocardium/metabolism , Actins/genetics , Animals , Cells, Cultured , Cytokines/genetics , Escherichia coli , Gene Expression/drug effects , Interferon-gamma/pharmacology , Interleukin-1/pharmacology , Interleukin-6/pharmacology , Myosin Heavy Chains/genetics , RNA, Messenger/analysis , Rats , Rats, Wistar , Time Factors , Tumor Necrosis Factor-alpha/pharmacology
16.
Naunyn Schmiedebergs Arch Pharmacol ; 363(4): 456-63, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11330340

ABSTRACT

RGS proteins (regulators of G protein signalling) negatively regulate G protein function as GTPase-activating proteins (GAP) for G protein alpha-subunits. The existence of mRNAs of different size for some of the RGS proteins, e.g. RGS3, suggests that these proteins may exist in isoforms due to alternative splicing. We therefore investigated RGS3 mRNA and protein expression in different human tissues. Ribonuclease protection assays and Northern blot analysis showed two specific mRNAs for RGS3 (RGS3L, RGS3S) in human myocardium, suggesting an additional, N-terminally truncated form of approximately 168 aa. When expressed as a recombinant protein RGS3S was recognized at approximately 23 kDa by an antipeptide antiserum originally raised against an RGS2 sequence. In membranes of human tissues this antiserum detected specific signals for RGS3L (approximately 70 kDa), RGS2 (approximately 30 kDa) and a 25-kDa protein, most likely RGS3S. Both RGS3S mRNA and the 25 kDa protein were abundant in human heart, whereas expression in liver, brain and myometrium was much weaker. To characterize RGS3S functionally, single turnover GTPase, adenylyl cyclase (AC) and phospholipase C (PLC) activities were determined. Both recombinant RGS3S and RGS16 increased Pi release from Galphai1 by about 150% and increased GTP- and GTP plus isoprenaline-stimulated AC activity by 20-30% in human left ventricular myocardial membranes. Additionally, both RGS proteins reduced basal and endothelin-stimulated PLC activity in these membranes by about 40%. We conclude that an additional truncated form of RGS3 is expressed in the human heart. As described for the full-length protein, RGS3S negatively regulates the activity of Gi/o- and Gq-, but not Gs-subfamily members.


Subject(s)
Brain/metabolism , GTP-Binding Proteins/metabolism , GTPase-Activating Proteins , Liver/metabolism , Myocardium/metabolism , RGS Proteins/physiology , Humans , Protein Isoforms , RGS Proteins/genetics
17.
J Biol Chem ; 276(4): 2474-9, 2001 Jan 26.
Article in English | MEDLINE | ID: mdl-11036069

ABSTRACT

The M(3) muscarinic acetylcholine receptor (mAChR) expressed in HEK-293 cells couples to G(q) and G(12) proteins and stimulates phospholipase C (PLC) and phospholipase D (PLD) in a pertussis toxin-insensitive manner. To determine the type of G protein mediating M(3) mAChR-PLD coupling in comparison to M(3) mAChR-PLC coupling, we expressed various Galpha proteins and regulators of the G protein signaling (RGS), which act as GTPase-activating proteins for G(q)- or G(12)-type G proteins. PLD stimulation by the M(3) mAChR was enhanced by the overexpression of Galpha(12) and Galpha(13), whereas the overexpression of Galpha(q) strongly increased PLC activity without affecting PLD activity. Expression of the RGS homology domain of Lsc, which acts specifically on Galpha(12) and Galpha(13), blunted the M(3) mAChR-induced PLD stimulation without affecting PLC stimulation. On the other hand, overexpression of RGS4, which acts on Galpha(q)- but not Galpha(12)-type G proteins, suppressed the M(3) mAChR-induced PLC stimulation without altering PLD stimulation. We conclude that the M(3) mAChR in HEK-293 cells apparently signals to PLD via G(12)- but not G(q)-type G proteins and that G protein subtype-selective RGS proteins can be used as powerful tools to dissect the pertussis toxin-resistant G proteins and their role in receptor-effector coupling.


Subject(s)
Heterotrimeric GTP-Binding Proteins/metabolism , Phospholipase D/metabolism , Receptors, Muscarinic/metabolism , Carbachol/pharmacology , Drug Resistance , GTP-Binding Protein alpha Subunits, G12-G13 , GTP-Binding Protein alpha Subunits, Gq-G11 , Humans , Muscarinic Agonists/pharmacology , Pertussis Toxin , RGS Proteins/metabolism , Receptor, Muscarinic M3 , Signal Transduction , Type C Phospholipases/metabolism , Virulence Factors, Bordetella/pharmacology
19.
J Biol Chem ; 275(42): 32543-51, 2000 Oct 20.
Article in English | MEDLINE | ID: mdl-10931825

ABSTRACT

Arginine vasopressin (AVP) regulates biological processes by binding to G protein-coupled receptors. In Swiss 3T3 fibroblasts, expressing the V(1a) subtype of vasopressin receptors, AVP mobilizes calcium from intracellular stores. In proliferating cells, the AVP-induced increase in intracellular calcium concentration ([Ca(2+)](i)) was mediated by G proteins of the G(q) family, which are insensitive to pertussis toxin (PTX) pretreatment of the cells. In quiescent cells, the AVP-induced increase in [Ca(2+)](i) was partially PTX-sensitive, suggesting an involvement of G(i) proteins. We confirmed this by photoaffinity labeling of G proteins in Swiss 3T3 cell membranes activated by AVP. In Swiss 3T3 cells arrested in the G(0)/G(1) phase of the cell cycle, the AVP-induced increase in [Ca(2+)](i) was also partially PTX-sensitive but was PTX-insensitive in cells arrested in other phases of the cell cycles. The blocking effect of PTX pretreatment in G(0)/G(1) cells was mimicked by microinjection of antisense oligonucleotides suppressing the expression of the Galpha(i3) subunits. These results were confirmed by microinjection of antibodies directed against the C terminus of G protein alpha-subunits. The data presented indicate that in Swiss 3T3 fibroblasts synchronized in the G(0)/G(1) phase of the cell cycle the V(1a) receptor couples to G(q/11) and G(i3) to activate the phospholipase C-beta, leading to release of intracellular calcium.


Subject(s)
Arginine Vasopressin/pharmacology , Cell Cycle/physiology , GTP-Binding Protein alpha Subunits, Gi-Go/metabolism , Heterotrimeric GTP-Binding Proteins/metabolism , Receptors, Vasopressin/physiology , 3T3 Cells , Affinity Labels , Animals , Antibodies/pharmacology , Calcium/metabolism , Cell Division , Cell Membrane/drug effects , Cell Membrane/metabolism , G1 Phase , GTP-Binding Protein alpha Subunits, Gi-Go/antagonists & inhibitors , GTP-Binding Protein alpha Subunits, Gi-Go/genetics , GTP-Binding Protein alpha Subunits, Gq-G11 , Heterotrimeric GTP-Binding Proteins/antagonists & inhibitors , Heterotrimeric GTP-Binding Proteins/genetics , Mice , Oligodeoxyribonucleotides, Antisense/pharmacology , Pertussis Toxin , Protein Subunits , Radioligand Assay , Receptors, Vasopressin/drug effects , Resting Phase, Cell Cycle , Virulence Factors, Bordetella/pharmacology
20.
J Biol Chem ; 275(37): 28500-6, 2000 Sep 15.
Article in English | MEDLINE | ID: mdl-10878019

ABSTRACT

RGS proteins are GTPase-activating proteins (GAPs) for G protein alpha-subunits. This GAP activity is mediated by the interaction of conserved residues on regulator of G protein signaling (RGS) proteins and Galpha-subunits. We mutated the important contact sites Glu-89, Asn-90, and Asn-130 in RGS16 to lysine, aspartate, and alanine, respectively. The interaction of RGS16 and its mutants with Galpha(t) and Galpha(i1) was studied. The GAP activities of RGS16N90D and RGS16N130A were strongly attenuated. RGS16E89K increased GTP hydrolysis of Galpha(i1) by a similar extent, but with an about 100-fold reduced affinity compared with non-mutated RGS16. As Glu-89 in RGS16 is interacting with Lys-210 in Galpha(i1), this lysine was changed to glutamate for compensation. Galpha(i1)K210E was insensitive to RGS16 but interacted with RGS16E89K. In rat uterine smooth muscle cells, wild type RGS16 abolished G(i)-mediated alpha(2)-adrenoreceptor signaling, whereas RGS16E89K was without effect. Both Galpha(i1) and Galpha(i1)K210E mimicked the effect of alpha(2)-adrenoreceptor stimulation. Galpha(i1)K210E was sensitive to RGS16E89K and 10-fold more potent than Galpha(i1). Analogous mutants of Galpha(q) (Galpha(q)K215E) and RGS4 (RGS4E87K) were created and studied in COS-7 cells. The activity of wild type Galpha(q) was counteracted by wild type RGS4 but not by RGS4E87K. The activity of Galpha(q)K215E was inhibited by RGS4E87K, whereas non-mutated RGS4 was ineffective. We conclude that mutation of a conserved lysine residue to glutamate in Galpha(i) and Galpha(q) family members renders these proteins insensitive to wild type RGS proteins. Nevertheless, they are sensitive to glutamate to lysine mutants of RGS proteins. Such mutant pairs will be helpful tools in analyzing Galpha-RGS specificities in living cells.


Subject(s)
GTP-Binding Proteins/physiology , Proteins , RGS Proteins/physiology , Adenylyl Cyclases/physiology , Animals , COS Cells , Calcium Channels/physiology , Female , GTP-Binding Proteins/chemistry , GTPase-Activating Proteins/physiology , Guanosine Triphosphate/metabolism , Mutation , RGS Proteins/chemistry , Rats , Rats, Wistar , Receptors, Adrenergic, alpha-2/physiology , Structure-Activity Relationship
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