ASSOCIATIONS BETWEEN INTERMEDIATE FILAMENT PROTEINS EXPRESSED IN CULTURED DORSAL-ROOT GANGLION NEURONS

The developmental profile of the neurofilament (NF) triplet proteins, alpha-internexin and peripherin in cultured dorsal root ganglion neuro ns from gestation day 15 rat embryos was determined by Western blot an alysis, At the outset (day 0 in culture), the neurons contained mostly alpha-internexin. A significant increase in peripherin levels was see n at days 1-2, in the mid-sized (NFM) and low molecular weight (NFL) N F subunits at days 2-3, and in the high molecular weight (NFH) NF subu nit at days 5-6. Immunofluorescence microscopy showed that the five in termediate filament proteins were co-localized in all neuronal cell bo dies and neurites, Analysis of Triton X-100 extracts from okadaic acid -treated dorsal root ganglion cultures revealed that peripherin and al pha-internexin followed the same fragmentation pattern observed with N Fs. Interactions between the various neuronal intermediate filament pr oteins in these extracts were assessed by immunoprecipitation under na tive conditions using antibodies specific for the individual proteins, Coimmunoprecipitation of NFH with NFL, NFM with NFL, NFM with alpha-i nternexin, and alpha-internexin with peripherin demonstrated that the intermediate filament cytoskeleton in cultured sensory neurons is a hi ghly integrated structure. (C) 1997 Wiley-Liss, Inc.