Y box-binding protein-1 binds preferentially to single-stranded nucleic acids and exhibits 3'-->5' exonuclease activity

We have previously shown that Y box-binding protein-1 (YB-1) binds preferentially to cisplatin-modified Y box sequences. Based on structural and biochemical data, we predicted that this protein binds single-stranded nucleic acids. In the present study we confirmed the prediction and also discovered some unexpected functional features of YB-1. We found that the cold shock domain of the protein is necessary but not sufficient for double-stranded DNA binding while the C-tail domain interacts with both single-stranded DNA and RNA independently of the cold shock domain. In an in vitro translation system the C-tail domain of the protein inhibited translation but the cold shock domain did not. Both in vitro pull-down and in vivo co-immunoprecipitation assays revealed that YB-1 can form a homodimer. Deletion analysis mapped the C-tail domain of the protein as the region of homodimerization. We also characterized an intrinsic 3'-->5' DNA exonuclease activity of the protein. The region between residues 51 and 205 of its 324-amino acid extent is required for full exonuclease activity. Our findings suggest that YB-1 functions in regulating DNA/RNA transactions and that these actions involve different domains.

[The effect of a water-cooled vest on heat intolerance in a patient with anhidrosis due to familial amyloidosis of Finnish type]

The patient was a 70-year-old male with familial amyloidosis of Finnish type who complained of heat intolerance due to anhidrosis during outdoor activities in summer. A water-cooled TM-2 vest was tried for this patient to reduce his body heat during exercises. Following the morning activities including jogging in August his body temperature rose up to 38.0 degrees C without wearing the partly frozen vest. However, when he wore it, his temperature rose up to only 37.2 degrees C after the exercises, which was 0.8 degree C lower than when he did not wear the vest. Headache and tachycardia during and following the morning activities did not appear by wearing the vest. In the heat loading test, in which the room temperature was raised from 28.0 degrees C to 38.0 degrees C for 15 minutes and kept at 38.0 degrees C for 60 minutes with 60% humidity, the rises of his skin and esophageal temperatures with wearing the partly frozen vest for the last 60 minutes were 1.2 degrees C and 0.4 degree C lower, respectively, than his skin and esophageal temperatures without wearing it. Concomitantly, the increase of heart rate was suppressed in the same test condition. Wet vest in running water showed the similar effects. Therefore, we concluded that the use of water-cooled TM-2 vest was effective in alleviating the symptoms and signs of his heat intolerance.

Lattice corneal dystrophy type II associated with familial amyloid polyneuropathy type IV

BACKGROUND

Finnish-type familial amyloidosis (FAP-IV) is an autosomal, dominantly inherited disorder characterized by progressive polyneuropathy and lattice corneal dystrophy type II. The vast majority of families with this disorder originated from Finland. Only two families, in neighboring districts, have been reported in Japan previously.

METHODS

The authors report two additional Japanese patients with FAF-IV. The proband, a 70-year-old man, had decreased perspiration and abnormal facial muscle movement. Results of neurologic examination showed bilateral facial and hypoglossal nerve palsies, and an autonomic disturbance, including orthostatic hypotension and dysfunction of perspiration. Histochemical, immunohistological, and DNA studies confirmed the diagnosis of FAP-IV.

RESULTS

Results of ophthalmologic examination showed asymptomatic lattice corneal dystrophy of both eyes, but the appearance of the cornea was different from that described in the patients from Finland. Lattice lines in the authors' patient were very fine, short, and glassy and could be observed with indirect retroillumination, but might be missed with direct illumination by the slit-lamp microscope. The proband's younger half-sister, a 68-year-old woman, showed clinical findings and laboratory data similar to those of the proband.

CONCLUSION

The authors report two Japanese patients with lattice corneal dystrophy type II related to FAP-IV. This is the third Japanese family with this disorder, and there is no familial relationship to the two previously reported families in Japan.

[Familial amyloidosis, Finnish type with marked anhidrosis]

Familial amyloidosis, Finnish type (FAF), is a gelsolin-related systemic amyloidosis that has an autosomal-dominant inheritance pattern and is clinically characterized by progressive cranial neuropathy, corneal lattice dystrophy and skin changes such as cutis laxa, blepharochalasis, and lichen amyloidosis. A 70-year-old Japanese male proband, who was believed to be originally from Fukuoka Prefecture, showed signs and symptoms characteristic of FAF. In addition, he complained of progressive anhidrosis and heat intolerance during the daytime in summer. On examination, perspiration was absent on the almost entire body surface. Molecular genetic studies showed a G-to-A transversion that resulted in the substitution of asparagine for aspartic acid 187 in the gelsolin gene, a mutation found in most patients with FAF. Skin biopsy revealed marked deposition of amyloid, which was positive with anti-gelsolin antibody staining, around eccrine sweat glands and ducts, and around sebaceous glands, outside the basal lamina; slight to mild deposition around small vessels and small nerve fascicles; and very slight deposition in the perineurium and endoneurium. Morphometric evaluation of the nerve terminals and axons of eccrine sweat glands revealed a significant decrease in the number of nerve terminals per transverse profile of the sweat gland. Compared with controls, nerve terminals were further from the secretory epithelial cell owing to deposition of amyloid outside its basal lamina. The proband's sister had almost identical, although much less severe, clinical signs and symptoms with the same mutation of the gelsolin gene. Autonomic signs and symptoms in FAF are reported to be less frequent and less severe than those in familial amyloid polyneuropathy of Andrade type. Findings in our proband suggest that perspiration may be markedly decreased in FAF owing to marked deposition of amyloid around the eccrine sweat gland which causes degeneration of the nerve terminals and disturbs access of the neurotransmitter to the secretory epithelial cell.