ABSTRACT
Metablastin (also called p19, stathmin, prosolin, p18, Lap18, and oncoprotein 18) is a highly conserved, cytosolic 149-amino acid polypeptide that is expressed in immature vertebrate cells and undergoes extracellular factor- and cell cycle-regulated serine phosphorylation. The protein was shown recently to destabilize microtubules in vitro (Belmont, L., and Mitchison, T. J. (1996) Cell 84, 623-631). Here we demonstrate that microinjection of recombinant metablastin induces a loss of microtubules in COS-7 cells. This effect is enhanced by serine-to-alanine mutations at several phosphorylation sites and virtually abolished by aspartate substitution at a single site, Ser-63. We also show that stoichiometric amounts of metablastin prevent assembly and promote disassembly of microtubules in vitro. Interestingly, the phosphorylation site mutations of metablastin that have dramatic differential effects in intact cells do not alter the ability of metablastin to block tubulin assembly in vitro. The data suggest that phosphorylation of metablastin controls its microtubule-destabilizing activity in vivo but that this regulation may require additional cellular factors. This control mechanism is poised to play a critical role in the dynamic reorganization of the cellular microtubule network that occurs during morphogenesis and mitosis.
Subject(s)
Microtubule Proteins , Microtubules/metabolism , Phosphoproteins/metabolism , Animals , Antineoplastic Agents/pharmacology , COS Cells , Interphase , Microinjections , Mutagenesis, Site-Directed , Nocodazole/pharmacology , Phosphorylation , Recombinant Proteins/metabolism , Serine/metabolism , StathminABSTRACT
52 patients with diabetic retinopathy stade III or IV (after Thiel) received on both eyes a photocoagulation treatment. 26 patients received subsequently Calciumdobesilate for 5 to 68 months. It could be shown, that the effect of photocoagulation treatment on alterations of the retina in diabetic patients was clearly enhanced by Calciumdobesilate.
Subject(s)
Benzenesulfonates/administration & dosage , Calcium Dobesilate/administration & dosage , Diabetic Retinopathy/therapy , Light Coagulation , Adult , Aged , Diabetic Retinopathy/drug therapy , Diabetic Retinopathy/surgery , Evaluation Studies as Topic , Female , Humans , Male , Middle AgedABSTRACT
The Non-Contact-Tonometer as developed by the American Optical Corporation, is in use superior to the traditional methods of intraocular-pressure measurements according to Schiötz and Goldmann: Without any manipulation on the eye the intra-ocular pressure can be measured rapidly and easily. Owing to the construction of the tonometer however measurements are only possible with smooth corneae. In addition to this the results of measurement with the NCT are not as exact as those of the traditional methods. Finally there is up to the present no possibility of standardising the new tonometer.
