G proteins and regulation of pyruvate dehydrogenase activity by insulin in human circulating lymphocytes

被引:10
作者
Curto, M
Piccinini, M
Rabbone, I
Mioletti, S
Mostert, M
Bruno, R
Rinaudo, MT
机构
[1] Univ Turin, Dipartimento Med & Oncol Sperimentale, Sez Biochim, I-10126 Turin, Italy
[2] Univ Turin, Dept Morfofisol Vet, I-10126 Turin, Italy
[3] Univ Turin, Dept Sci Pediat & Adolescenza, I-10126 Turin, Italy
关键词
G proteins; insulin; pertussis toxin; pyruvate dehydrogenase;
D O I
10.1016/S1357-2725(97)00049-6
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Pertussis toxin (PT) catalyzes ADP-ribosylation of G protein alpha subunits, thus preventing their role as transducers of external signals targeting metabolic pathways. In vitro, in human circulating lymphocytes insulin at physiological concentrations (5 mu U/ml) determines sharp activation of pyruvate dehydrogenase (PDH), the rate limiting enzyme in glucose oxidative breakdown. This study evaluates whether the above-described effects of insulin over PDH are mediated through G proteins. Human circulating lymphocytes (six samples from different donors) were exposed to insulin (5 mu U/ml), PT (1-2 mu g/ml) or PT-9K, a mutated PT void of catalytic activity (1-10 mu g/ml), and to insulin in combination with the two toxins, and then assessed for PDH activity. Plasma membranes from cells incubated,vith and without PT or PT-9K were subjected to ADP-ribosylation in the presence of [P-32] NAD(+) and activated PT. In circulating lymphocytes exposed to PT alone, or in combination with insulin, PDH activity falls significantly below basal values (P < 0.001); PT-BK instead has no effect on basal or on insulin-stimulated PDH activity. ADP-ribosylation of a plasma membrane component with apparent molecular mass (42 kDa) comparable to that of the Gi (inhibitory) protein alpha subunit takes place in cells exposed to PT but not in those exposed to PT-9K. In human circulating lymphocytes Gi proteins or Gi protein-like components appear to be involved in preserving basal PDH activity as well as in the mechanism by which insulin exerts its control over PDH. (C) 1997 Elsevier Science Ltd.
引用
收藏
页码:1207 / 1217
页数:11
相关论文
共 50 条
[1]  
Bushfield M, 1990, Biochem Soc Symp, V56, P137
[2]  
CASEY PJ, 1988, J BIOL CHEM, V263, P2577
[3]   ROLE OF GUANINE-NUCLEOTIDE REGULATORY PROTEINS IN INSULIN STIMULATION OF GLUCOSE-TRANSPORT IN RAT ADIPOCYTES - INFLUENCE OF BACTERIAL TOXINS [J].
CIARALDI, TP ;
MAISEL, A .
BIOCHEMICAL JOURNAL, 1989, 264 (02) :389-396
[4]   INSULIN MODULATION OF PYRUVATE-DEHYDROGENASE IN HUMAN CIRCULATING LYMPHOCYTES [J].
CURTO, M ;
PICCININI, M ;
BRUNO, R ;
MOSTERT, M ;
RINAUDO, MT .
INTERNATIONAL JOURNAL OF BIOCHEMISTRY, 1988, 20 (11) :1211-1217
[5]   THE INSULIN SIGNAL AND ITS EFFECTS ON THE PYRUVATE-DEHYDROGENASE COMPLEX IN CIRCULATING LYMPHOCYTES OF OBESE CHILDREN [J].
CURTO, M ;
PICCININI, M ;
CERUTTI, F ;
RABBONE, I ;
MOSTERT, M ;
SACCHETTI, C ;
BRUNO, R ;
RINAUDO, MT .
INTERNATIONAL JOURNAL OF BIOCHEMISTRY, 1992, 24 (05) :831-837
[6]   DOES MITOGEN-ACTIVATED-PROTEIN KINASE HAVE A ROLE IN INSULIN ACTION - THE CASES FOR AND AGAINST [J].
DENTON, RM ;
TAVARE, JM .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1995, 227 (03) :597-611
[7]   SOME THOUGHTS ON THE MECHANISM OF ACTION OF INSULIN [J].
EXTON, JH .
DIABETES, 1991, 40 (05) :521-526
[8]   ABOLITION OF THE EXPRESSION OF INHIBITORY GUANINE-NUCLEOTIDE REGULATORY PROTEIN-GI ACTIVITY IN DIABETES [J].
GAWLER, D ;
MILLIGAN, G ;
SPIEGEL, AM ;
UNSON, CG ;
HOUSLAY, MD .
NATURE, 1987, 327 (6119) :229-232
[9]   G-PROTEINS - TRANSDUCERS OF RECEPTOR-GENERATED SIGNALS [J].
GILMAN, AG .
ANNUAL REVIEW OF BIOCHEMISTRY, 1987, 56 :615-649
[10]   ACTION OF INSULIN MODULATED BY PERTUSSIS TOXIN IN RAT ADIPOCYTES [J].
GOREN, HJ ;
NORTHUP, JK ;
HOLLENBERG, MD .
CANADIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY, 1985, 63 (08) :1017-1022