Functional decline in Huntington's disease.

We prospectively evaluated 129 patients with manifest Huntington's disease (HD) to determine the rate of illness progression and the clinical features that correlate with functional decline. A single examiner evaluated each patient using the HD Functional Capacity Scale. Standardized motor performance was also assessed in 94 of the patients (73%) using the HD Rating Scale.

Trinucleotide repeat length and progression of illness in Huntington's disease.

The genetic defect causing Huntington's disease (HD) has been identified as an unstable expansion of a trinucleotide (CAG) repeat sequence within the coding region of the IT15 gene on chromosome 4. In 50 patients with manifest HD who were evaluated prospectively and uniformly, we examined the relationship between the extent of the DNA expansion and the rate of illness progression. Although the length of CAG repeats showed a strong inverse correlation with the age at onset of HD, there was no such relationship between the number of CAG repeats and the rate of clinical decline.

Expression of a transmembrane phosphotyrosine phosphatase inhibits cellular response to platelet-derived growth factor and insulin-like growth factor-1.

Tyrosine phosphorylation is a mechanism of signal transduction shared by many growth factor receptors and oncogene products. Phosphotyrosine phosphatases (PTPases) potentially modulate or counter-regulate these signaling pathways. To test this hypothesis, the transmembrane PTPase CD45 (leukocyte common antigen) was expressed in the murine cell line C127.

Differential dephosphorylation of the insulin receptor and its 160-kDa substrate (pp160) in rat adipocytes.

A permeabilized rat adipocyte model was developed which permitted an examination of: 1) insulin receptor autophosphorylation, 2) phosphorylation of a putative insulin receptor substrate of 160 kDa, pp160, and 3) the dephosphorylation reactions associated with each of these phosphoproteins. Rat adipocytes, preincubated with [32P]orthophosphate for 2 h, were exposed to insulin (10(-7) M) at the time of digitonin permeabilization. Phosphorylation of pp160 and autophosphorylation of the insulin receptor increased as a function of Mn2+ concentration in the media with near maximum responses at 10 mM.

Insulin stimulates the tyrosine phosphorylation of a 61-kilodalton protein in rat adipocytes.

Insulin stimulated the tyrosine phosphorylation of a 61-kilodalton (kDa) protein in rat adipocytes prelabeled for 2 h with [32P]orthophosphate. Tyrosine phosphorylation of this 61-kDa protein displayed very similar insulin concentration dependency to receptor autophosphorylation and tyrosine phosphorylation of a high molecular mass receptor substrate of 160 kDa. Phosphorylation of the 61-kDa protein was very rapid with maximum labeling attained at 30 sec, paralleling that of the other two proteins.

Counter-regulation by insulin and isoprenaline of a prominent fat-associated phosphoprotein doublet in rat adipocytes.

1. In the adipocyte, phosphorylation/dephosphorylation of regulatory proteins is a common mechanism of metabolic regulation. We have observed a very prominent phosphoprotein doublet of 61 kDa and 63 kDa in rat adipocytes that is markedly responsive to hormones.

The insulin-like effect of vanadate on lipolysis in rat adipocytes is not accompanied by an insulin-like effect on tyrosine phosphorylation.

Tyrosine phosphorylation of the insulin receptor and other intracellular proteins in rat adipocytes was examined using an immunoblot technique with antiphosphotyrosine antibody. Insulin at 10(-7) M increased the tyrosine phosphorylation of the 95K subunit of the insulin receptor (15-fold) and proteins of 180K (7-fold) and 60K (23-fold). Increases in insulin-dependent phosphorylation of the three proteins were detectable at 10(-10) M insulin and attained steady state within 30 sec of insulin (10(-7) M) addition.