Insulin-receptor phosphotyrosyl-protein phosphatases

King, M. S.; Sale, Graham J.

doi:10.1042/bj2560893

Cited by 43 publications

(26 citation statements)

References 47 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Dephosphorylation assays. [ 32 P]IR preparation or [ 32 P]GS (-25,000-50,000 cpm/10 \L\) were incubated at 30°C with and without particulate or cytosol (0-24 |xg protein/assay) in final vol 40 n-l as described earlier (29). Dephosphorylation reaction was initiated by the addition of 10 ixl 32 P-labeled receptor preparation or GS for the indicated periods of time.…”

Section: Methodsmentioning

confidence: 99%

“…The homogenate was centrifuged at 500 x g for 5 min. The particulate and soluble fractions were isolated by centrifugation at 100,000 x g for 1 h (29). The pellet (particulate) was resuspended in 0.5 ml of the above mentioned buffer and frozen at -70°C in small aliquots.…”

Section: Methodsmentioning

confidence: 99%

“…PTPase activity is present in both particulate and cytosolic fractions (19,20,29,(35)(36)(37). It is possible that diabetes may promote redistribution of PTPases between cytosol and particulate fractions.…”

Section: Effect Of Diabetes On Adipocyte Ptpases and Pspasesmentioning

confidence: 98%

See 2 more Smart Citations

Differential Effects of Diabetes on Adipocyte and Liver Phosphotyrosine and Phosphoserine Phosphatase Activities

1991

View full text Add to dashboard Cite

We examined the activities of particulate and cytosolic phosphotyrosine phosphatase (PTPase) and phosphoserine phosphatase (PSPase) in adipocytes and livers of diabetic rats. PTPase activity was assessed with [32P]tyrosine-phosphorylated insulin receptor (IR), whereas PSPase activity was assayed with [32P]serine-phosphorylated glycogen synthase. Diabetes increased adipocyte particulate PTPase activity and enhanced IR dephosphorylation by 75% on the 2nd, 93% on the 14th, and 108% on the 30th day. In contrast, cytosolic PTPase activity decreased by 78% on the 14th and 45% on the 30th day (no change on the 2nd day). Similar changes were observed with PSPase (increased activity in particulate and decreased in cytosolic). Insulin therapy for 14 or 30 days restored PTPase and PSPase activities in both fractions. Vanadate, despite rapid normalization of glycemia, restored these activities only after 30 days of therapy. Diabetes-related changes in liver PTPase activity were observed on the 14th day only. At this time, it was increased in both particulate and cytosolic fractions. There was spontaneous normalization of the liver PTPase activity at 30 days of diabetes. In contrast, liver cytosolic PSPase activity was significantly inhibited and not normalized by the 30th day of disease without therapy. In summary, diabetes appears to induce tissue-specific changes in PTPase and PSPase activities resulting in significant alterations in dephosphorylation of IR and glycogen synthase. Moreover, there appears to be a differential regulation of PTPase and PSPase activities in diabetes, particularly in the liver.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Differential Effects of Diabetes on Adipocyte and Liver Phosphotyrosine and Phosphoserine Phosphatase Activities

1991

View full text Add to dashboard Cite

show abstract

“…Immunocomplexes were washed and resuspended in 25 mM Hepes (pH 7.5) containing 5 mM EDTA, 1 mM dithiothreitol, and protease inhibitors (15). Particulate and cytosolic fractions from sand rat liver, prepared as described (15), were added to the immunocomplexes to evaluate protein-tyrosine phosphatase activity. After incubation for 20 min at 300C, the dephosphorylation reaction was terminated by adding Laemmli sample buffer and boiling for 5 min.…”

mentioning

confidence: 99%

Hyperinsulinemia induces a reversible impairment ininsulin receptor function leading to diabetes in the sand rat model ofnon-insulin-dependent diabetes mellitus.

Kanety

Moshe

Shafrir

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The insulin receptor was evaluated at different disease stages in the sand rat (Psammomys obesus), a model for nutrition-induced diabetes. Nondiabetic sand rats showed markedly low receptor number in liver compared with albino rats. Their receptor had an intact tyrosine kinase activity but a higher K. for ATP in the phosphorylation reaction of exogenous substrates. The initial effects of overeating (i.e., development of hyperinsulinemia without hyperglycemia) were associated in the sand rat with a dramatic decrease in in vitro and in vivo insulin-induced receptor tyrosine kinase activity in both liver and muscle. In muscle, this coincided with a decrease in receptor number and an increase in basal tyrosine kinase activity. Similar canges were observed upon development of hyperinsulinemia with hyperglycemia. Upon recovery from the diabetic state by diet restriction, the impaired receptor kinse activation was corrected. Complete restoration occurred only in animals that fully recovered from the diabetic state and became normoinLinemic. These observations indicate that loss and gain of receptor tyrosine kinase activity were dependent on insulin levels. Thus, overeating may lead to the development of hyperinsulinemia through ineffective extraction of excess insulin by the scarce liver receptors. Hyperinsulinemia, in turn, causes a reversible reduction in receptor kinase activity, leading to insulin resistance. This sequence of events may be relevant to diet-related changes in human non-insulin-dependent diabetes mellitus.The development of non-insulin-dependent diabetes mellitus (NIDDM) in the majority of patients occurs in parallel to weight gain (1). Overeating is initially followed by hyperinsulinemia and insulin resistance, which gradually develop into pronounced hyperglycemia. This diabetogenic process may be reversed by diet restriction and weight loss (2). Since both hyperinsulinemia and insulin resistance coincide with weight gain in humans, it is not feasible to determine which is the primary event mediating the effect of obesity. We have addressed this query in an animal model of NIDDM. The sand rat is a desert-adapted gerbil that in its natural habitat is nondiabetic (3-7). In captivity, on an ad libitum rodent diet, it develops obesity and hyperinsulinemia without or with hyperglycemia (6,7). Through control of the animals' diet, it is possible to discern several stages of development of glucose intolerance, as well as reverse them, thus addressing the sequence of events that lead to induction of diabetes. We studied the insulin receptor (IR) function in these wellcharacterized animals and found alterations that may be relevant to human nutrition-induced diabetes. ['t-32P]ATP was from Amersham. ATP, CTP, Hepes, Tween 20, poly(Glu8Tyr20), bovine serum albumin (insulin free), N-acetyl-D-glucosamine, leupeptin, aprotinin, soybean trypsin inhibitor, and phenylmethylsulfonyl fluoride were from Sigma. Wheat germ agglutinin (WGA) and Con A coupled to agarose were from Bio-Makor (Rehovot, Israel). Reagen...

show abstract

“…Inhibition of autophosphorylation could have several explanation. Since these effects were prevented by the addition of vanadate, the decrease in receptor phosphorylation may have been due to a tyrosine phosphatase copurified with the receptor [39,401. In this respect, the question remains how the phosphopeptide interfered with the action of the phosphatase.…”

Section: Discussionmentioning

confidence: 99%

Kinase inhibition by a phosphorylated peptide corresponding to the major insulin receptor autophosphorylation domain

Chavanieu¹,

Calas²,

Vaglio³

et al. 1992

European Journal of Biochemistry

View full text Add to dashboard Cite

We studied the inhibitory effect of non-phosphorylated and triphosphorylated synthetic peptides, corresponding to amino acids 1143-1155 of the insulin proreceptor (domain 1151) on autophosphorylation and kinase of the insulin receptor. Tyrosine-phosphorylated peptides were synthesized using the N-(9-fluorenylmethoxycarbonyl)-O-dibenzylphosphono-~-tyr0~~ne.The triphosphorylated peptide (1 1 51-P3) and the non-phosphorylated peptide (1 151-NP), respectively, inhibited insulin receptor autophosphorylation by 65% and 70%, in a dose-dependent and additive manner. When the receptor was pre-phosphorylated for 1 min with [y-32P]ATP, 1151-P3 decreased autophosphorylation to 60% of maximun, whereas 11 51-NP had no further effect. In both non-activated and preactivated receptors, 1 151-P3 inhibition of receptor autophosphorylation was prevented by adding 2 mM vanadate. Kinase activity towards exogenous substrate poly(Glu,, Tyr) was dose-dependently inhibited by both analogues. This effect was independent of the state of receptor phosphorylation or the addition of vanadate. Since 11 51 -P3 inhibited the exogenous kinase without altering receptor endogenous autophosphorylation after the addition of vanadate, we investigated 11 51-NP and 11 51-P3 competition for the phosphorylation of a resin-immobilized 1151 peptide. While 11 51 -NP (at 2 mM) was highly competitive, inhibiting phosphate incorporation by 70%, 11 51-P 3 caused a four-fold increase in the phosphorylation of 1151-NP -resin. The receptor underwent conformational changes during autophosphorylation and an antibody directed against a peptide corresponding to amino acids 1334-1330 of the proreceptor (1322Ab) was previously shown to immunoprecipitate specifically the non-phosphorylated reccptor forms. Nevertheless, the 1322Ab irnmunoprecipitated a fully autophosphorylated receptor in the presence of 1151-NP, but not of 1151-P3, thus suggesting a conformational change induced by the non-phosphorylated peptide.In conclusion, kinase inhibition was still observed after the addition of phosphate groups to three 11 51 -peptide tyrnsines, but the peptide effect on receptor autophosphorylation, phosphorylation of homologous 1151-NP -resin and conformational changes induced in the receptor was altered dramatically. These data may provide a basis for further understanding the role of tyrosine phosphorylation in insulin receptor kinase activation or regulation.The insulin receptor is a complex heterotetrameric glycoprotein of the plasma membrane and is composed of two distinct subunits [l -31. The 135-kDa CI subunit contains a high affinity insulin binding site and is externally oriented [4].The B subunit is a 95-kDa transmembrane protein which contains a tyrosine-specific protein kinase in the cytoplasmic domain [ 5 , 6 ] . Insulin binding to the CI subunit rapidly induces kinase activation of the p subunit, which undergoes auto- Abbreviutions. RP, reverse phase; HPCE, high-performance capillary electrophoresis; Fmoc, 9-fluorenylmethoxycarbonyl; Boc, t-butyloxycarbonyl; TyrO(P...

show abstract

Insulin-receptor phosphotyrosyl-protein phosphatases

Cited by 43 publications

References 47 publications

Differential Effects of Diabetes on Adipocyte and Liver Phosphotyrosine and Phosphoserine Phosphatase Activities

Differential Effects of Diabetes on Adipocyte and Liver Phosphotyrosine and Phosphoserine Phosphatase Activities

Hyperinsulinemia induces a reversible impairment ininsulin receptor function leading to diabetes in the sand rat model ofnon-insulin-dependent diabetes mellitus.

Kinase inhibition by a phosphorylated peptide corresponding to the major insulin receptor autophosphorylation domain

Contact Info

Product

Resources

About