Sorting in early endosomes reveals connections to docking- and fusion-associated factors

The early endosomes constitute a major sorting platform in eukaryotic cells. They receive material through fusion with endocytotic vesicles or with trafficking vesicles from the Golgi complex and later sort it into budding vesicles. While endosomal fusion is well understood, sorting is less characterized; the 2 processes are generally thought to be effected by different, unrelated machineries. We developed here a cell-free assay for sorting/budding from early endosomes, by taking advantage of their ability to segregate different cargoes (such as transferrin, cholera toxin subunit B, and low-density lipoprotein, LDL) into different carrier vesicles. Cargo separation required both carrier vesicle formation and active maturation of the endosomes. Sorting and budding were insensitive to reagents perturbing clathrin coats, coatomer protein complex-I (COPI) coats, dynamin, and actin, but were inhibited by anti-retromer subunit antibodies. In addition, the process required Rab-GTPases, phosphatidylinositol-3-phosphate, and, surprisingly, the docking factor early endosomal autoantigen 1 (EEA1). Sorting also required the function of the N-ethylmaleimide-sensitive factor (NSF), a well-known fusion cofactor, while it did not depend on preceding fusion of endosomes. We conclude that fusion, docking, and sorting/budding are interconnected at the molecular level.     

Quantitative EEG analysis for assessment to 'plan' a task in amyotrophic lateral sclerosis patients: a study of executive functions (planning) in ALS patients

An attempt has been made to study the ability of patients with amyotrophic lateral sclerosis (ALS) to 'plan' a task. Electroencephalogram (EEG) data corresponding to 'planning of a movement task' is analyzed in comparison with a normal relaxed state. The study was conducted on 12 patients with ALS (6 males, 3 females, mean age 46.75 years) and on same number of controls (10 males, 2 females, mean age 48.75 years) to evaluate a difference in the ability to 'plan' a movement task between them. Patients with ALS were divided in two groups defined by unclear/clear speech. It has been observed that patients with ALS having unclear speech (Group I) showed considerable reduction (p<0.0001) in 'planning' a movement task, whereas patients with ALS having clear speech (Group II) showed no deficit in 'planning' a movement task (p=0.0577), both in comparison with age-matched controls. Apart from supporting the earlier reports of a possible extended neuronal degeneration across wide area of the frontal lobes, the findings reveal a possible reduction in planning, an executive function of the prefrontal cortex of brain, and also reveal that speech impairment may be associated with cognitive deficits in patients with ALS.