Disease relevance of Nefl

• The amount of NF-L correlated with the cell count in the ganglion cell layer and the axon number in the optic nerve at 7 days after kainate injection [1].
• The purpose of this study is to evaluate the changes in neurofilament light (NF-L) protein in the optic nerve in rat kainate and monkey ocular hypertension models [1].
• Nociception induced breakdown of NFL in the spinal cord and dorsal root ganglias was prevented by pretreatment of the animals with a single dose of the specific inhibitor of the protease calpain (MDL-28170) which has been shown to be the primary protease involved in neurofilament degradation in neurodegenerative diseases [2].
• Likewise, ischemia/reperfusion caused significant decreases in the levels of Thy-1 and NF-L mRNAs and in the b-wave amplitude of the electroretinogram [3].
• In NF-L-expressing PC12 cells, the promoter was unmethylated, whereas in non-expressing glioma C6 cells intensive methylation occurred [4].

High impact information on Nefl

• The 66 kd protein constituted 0.5% of total protein in the spinal cord, whereas NF-L constituted about 1.5% [5].
• To examine this and to further investigate the function of the carboxyl-terminal tail domain of NF-M, we made various deletion mutants that lacked part of their tail domains, and we expressed these with NF-L [6].
• We examined the differential expression of genes encoding three beta-tubulin isotypes (classes I, II, and IV) and the 68-kDa neurofilament protein (NF68) in rat sensory neurons during development, maturation, and axonal regeneration [7].
• Hybridization with specific cDNAs was used to measure levels of mRNA encoding the 68-kDa neurofilament protein (NF68), beta-tubulin, and actin in lumbar sensory neurons of rat at various times after crushing the sciatic nerve [8].
• Within 24 hr of axotomy, there was a down-regulation of the 68 kDa (NF-L) and 145 kDa (NF-M) NF subunits [9].

Chemical compound and disease context of Nefl

• The activation of cyclic AMP-dependent protein kinase (PKA) in rat dorsal root ganglion (DRG) cultures increased phosphorylation of the low-molecular-mass neurofilament subunit (NFL) at a site previously identified as Ser55 but had no effect on neurofilament integrity [10].
• Intraocular injection of NMDA caused substantial reductions in the mRNA levels of the ganglion cell-specific markers Thy-1 and neurofilament light (NF-L) [3].
• Terbutaline administered on postnatal days PN2 to 5 elicited neurochemical changes indicative of neuronal injury and reactive gliosis: immediate increases in glial fibrillary acidic protein and subsequent induction of the 68-kDa neurofilament protein [11].
• To investigate the mechanism of diminished NF content, subunit (NF-L, -M and -H) gene expression was quantified in dorsal root ganglion (DRG) of slightly affected and moderately intoxicated groups of rats exposed to 2,5-hexanedione (HD) at one of three daily dosing rates (175, 250 and 400 mg/kg per day) [12].

Biological context of Nefl

• For functional analysis of the NF-L promoter, constructs carrying 38, 97, 407, 564, 650, 1,099, 1,660, 2,003 base pairs (bp) upstream region in front of the chloramphenicol acetyltransferase (CAT) reporter gene were tested for their capability to direct CAT expression after transient transfection into various cell lines [13].
• Identification of serine 473 as a major phosphorylation site in the neurofilament polypeptide NF-L [14].
• An "immature" form of NFs, composed of NF-M and NF-L, appears to function in establishing the neuronal phenotype and in initiating and maintaining neurite outgrowth [15].
• Restoration of axonal contact in the growing nerve stimulates the recapitulation of Schwann cell differentiation including the elevation of NF-M and NF-L mRNA expression [16].
• Detection of NF-L and NF-M mRNA in injured nerve, however, indicated that there was an up-regulation in response to nerve injury [17].

Anatomical context of Nefl

• The role of these factors in NF-L gene transcriptional induction by NGF in PC12 cells is discussed [13].
• NF-L in optic nerve extract was quantified by quantitative immunoblot using an imaging analyzer [1].
• Moreover, serine 473 is a major phosphorylation site in vivo; in neurofilaments isolated from rat spinal cord, approximately 73% of serine 473 was phosphorylated, and accounted for at least one-third of the total phosphate associated with NF-L [14].
• Compared with age-matched controls, neurofilament heavy (NF-H) (3.3-fold) and neurofilament medium (NF-M) (2.5-fold), but not neurofilament light (NF-L), subunits accumulated in the proximal axon of sensory neurons of the lumbar dorsal root ganglia (DRG) in untreated diabetic rats [18].
• The developmentally regulated intracellular intermediate filament protein neurofilament (NF), composed of the light (NF-L), medium (NF-M) and high (NF-H) molecular weight isoforms, is expressed abundantly in nerve cells but its significance in nerve cell survival in stress situations in the brain is unknown [19].

Associations of Nefl with chemical compounds

• The amount of NF-L in the optic nerve was significantly reduced in kainate-treated eyes (vs. normal eyes) [1].
• We report here that serine 473, in the carboxy-terminal tail domain of NF-L, is a major substrate in vitro for protein kinases endogenous to a crude cytoskeleton-containing fraction [14].
• Chronic, but not acute, administration of either morphine or cocaine was found to decrease levels of the three NF proteins, NF-200 (NF-H), NF-160 (NF-M), and NF-68 (NF-L), by between 15% and 50% in the VTA by back phosphorylation, immunolabeling, and Coomassie blue staining [20].
• Here we used techniques for the mass spectrometric sequencing of proteins from polyacrylamide gels to analyze in vivo phosphorylation sites on NF-M and NF-L [21].
• NF-M and NF-L are known to be modified by O-linked N-acetylglucosamine (O-GlcNAc) (Dong, D. L.-Y., Xu, Z.-S., Chevrier, M. R., Cotter, R. J., Cleveland, D. W., and Hart, G. W. (1993) J. Biol. Chem. 268, 16679-16687) [22].

Other interactions of Nefl

• Rat NF-L promoter contained Sp1, AP-2 and CGCCCCCGC elements [13].
• RNA blot analyses with total RNA obtained from DRGs at different postaxotomy times confirmed that NF-L mRNA levels were reduced in the DRG during the first 4 weeks after axotomy but, interestingly, failed to detect an increase in peripherin mRNA levels [23].
• The pellet contained the bulk of the cytoskeleton proteins from tissue, identified as the 150- and 68-kDa subunits of neurofilaments (NF-M and NF-L, respectively), the 66-kDa associated protein, the 57-kDa intermediate filament-like protein, and the 50-kDa glial fibrillary acidic protein [24].
• Western analysis indicated degradation of 68 kDa neurofilament protein (NFP), a calpain substrate [25].
• S-100beta, 5HT, 5HT-transporter (5HT-T) and neurofilaments (Nf-200 and Nf-68) expressions were studied by immunohistochemistry and image analysis in striatum, hippocampus, parietal and frontal cortex [26].

Analytical, diagnostic and therapeutic context of Nefl

• In situ hybridization showed that NF-L mRNA was localized in the Schwann cell perinuclear area, in the myelin sheath, and at the boundary between myelin sheath and cortical axoplasm [17].
• RT-PCR demonstrated the presence of NF-L, NF-M and NF-H mRNAs in intact sciatic nerve, as well as in proximal and distal stumps of severed nerves [17].
• Electrophoretic mobility shift assays confirmed these results but showed that the nuclear proteins induced by PKA which bound to the NF-L promoter Sp1-like sequence were not Sp1 [27].
• Northern blotting revealed that NF-L and NF-M mRNAs were present at very low levels in embryonic brain and that significant expression of these genes only occurred postnatally when the levels increased dramatically until P28 and then declined again in the adult [28].
• Compared to that of the control group, the levels of NF-L increased respectively by 104% and 45% (P<0.01) in the supernatant and decreased by 16% and 11% (P<0.01) in the pellet of rat cerebrums in lower and higher groups [29].

References