The effect of rod domain A148V mutation of neurofilament light chain on filament

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BMB Rep. 2008 Dec 31;41(12):868-74.

The effect of rod domain A148V mutation of neurofilament light chain

on filament formation.

Lee IB, Kim SK, Chung SH, Kim H, Kwon TK, Min do S, Chang JS.

Department of Life Science, College of Natural Science, Daejin

University, Pocheon, Korea

Neurofilaments (NFs) are neuronal intermediate filaments composed of

light (NF-L), middle (NF-M), and heavy (NF-H) subunits. NF-L self-

assembles into a " core " filament with which NF-M or NF-H co-assembles

to form the neuronal intermediate filament.

Recent reports show that point mutations of the NF-L gene result in

Charcot-Marie-Tooth disease (CMT). However, the most recently

described rod domain mutant of human NF-L (A148V) has not been

characterized in cellular level.

We cloned human NF-L and used it to engineer the A148V. In phenotypic

analysis using SW13 cells, A148V mutation completely abolished

filament formation despite of presence of NF-M. Moreover, A148V

mutation reduced the levels of in vitro self-assembly using GST-NF-L

(H/R) fusion protein whereas control (A296T) mutant did not affect

the filament formation.

These results suggest that alanine at position 148 is essentially

required for NF-L self-assembly leading to subsequent filament

formation in neuronal cells.