General News for June
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The news in brief
Best online site for CJD abstracts?
New neurodegeneration gene (HSS) maps by prion gene
Bovine prion mRNA exon 1: tissue-specific alternative splicing
New route of exposure: carotid dura mater embolization
Both prion allotypes accumulate in sporadic and Val 21O lle CJD
Protease alleles don't affect sporadic CJD
The psychiatric manifestation of CJD and mis-diagnosis

Turn-around: from June 5 Nature, page 560, 1997. It seems in the 1930's, Norman Pirie and Fred Bawden purified TMV (tobacco mosaic virus) to homogenity, even crystallizing it, and showed conclusively that every infectious particle contained nucleic acid (its RNA genome). This went against the grain of conventional wisdom of the day -- in the person of Wendell Stanley, subsequent Nobel laureate, who held that TMV and other viruses consisted entirely of protein!

Help wanted: from June 5 Nature, ad in the back Collinge's group is looking for a research technician to help with on-going projects such as determination of human prion 3D structure, mechanism of conversion to disease isoform, site=directed mutagenesis, heterologous gene expression, and NMR, X-ray, fluorescence, steady-state and transient kinetics. (Pay is 16,000 pounds or $26,400.)

Three online access points to Medline abstracts were tested on June 19, 1997. PubMed is still the best, especially for the latest articles, though BioMedNet goes back farther [but often has just a title] and has more links to for-pay fulltext. Here's how they stacked up on hits using the keyword 'prion':

Publication Date BioMedNet PubMed HealthGate
'59-64 0 na 0
'65-70 0 na 0
'71-97 1118 na 1138
ALL dates 1118 1206 1138
1997 35 89 35
1996 237 251 242
1995 131 171 171

Neurodegeneration gene for HSS maps near prion gene

Nat Genet 14 (4): 479-481 (Dec 1996)  
Taylor TD, ... Bertini E, Hayflick SJ.
Commentary: The human genome location of Hallervorden-Spatz Syndrome, aka neurodegeneration with brain iron accumulation (NBIA1), is chromosome 20p12.3-p13, very close to where the prion gene is located.

HSS is a rare, autosomal recessive neuro-degenerative disorder with brain iron accumulation as a prominent finding. It was first described in 1922. Although the chemical state of the iron never seems to have been determined, in Ann Neurol 18 (4): 482-489 (Oct 1985) a block in the metabolic pathway from cysteine to taurine, with acccumulated cysteine binding iron and accounting for the local increase in iron content in HSS was proposed. The combined excess of cysteine and ferrous iron may generate free radicals that damage neuronal membranes to cause the typical morphological changes observed in this disorder. Paramagnetic effect of copper could be confused wtih iron on MRI.

However, pathologic brain iron accumulation is seen in common disorders, including Parkinson's disease, Alzheimer's disease and Huntington disease. Clinical features of HSS include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. It occurs either as a familial or a sporadic disorder and can have neurofibrillary tangles or Lewy bodies. HSS has not been tested for staining by Congo red; CJD has not been associated with iron accumulation, as per Medline search of 6.18.97.

The HSS gene is not sequenced yet and there is no clue as to normal role. It seems possible that it is a new type of mutation in prion gene that has gone unrecognized because it doesn't have a familiar CJD phenotype. Fatal Familial Insomnia also started off as a separate disorder until it was mapped and the prion gene defect determined. D Selkoe, a keynote speaker at the Copper Mountain amyloid conference July 13, worked on HSS in the late 80's: will a connection to prion disease be announced.

The HSS gene is located in a 4-cM interval between D20S906 and D20S116, whereas the prion gene is at:

AFM057xa3                D20S194                  PRNP                     
AFM058xa1                D20S195                  PrP  
CJD                      D20S906                  WI-15220  
GSS                      D20S110                  WI-5288   

Homozygosity mapping of Hallervorden-Spatz syndrome to chromosome 20p12.3-p13.

Nat Genet 14 (4): 479-481 (Dec 1996) 
Taylor TD, Litt M, Kramer P, Pandolfo M, Angelini L, Nardocci N, Davis S,
Pineda M, Hattori H, Flett PJ, Cilio MR, Bertini E, Hayflick SJ
Hallervorden-Spatz syndrome (HSS) (OMIM #234200) is a rare, autosomal recessive neurode-generative disorder with brain iron accumulation as a prominent finding. Clinical features include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. Histologic study reveals massive iron deposits in the basal ganglia. Systemic and cerebrospinal fluid iron levels are normal, as are plasma levels of ferritin, transferrin and ceruloplasmin. Conversely, in disorders of systemic iron overload, such as haemochromatosis, brain iron is not increased, which suggests that fundamental differences exist between brain and systemic iron metabolism and transport. In normal brain, non-haem iron accumulates regionally and is highest in basal ganglia. Pathologic brain iron accumulation is seen in common disorders, including Parkinson's disease, Alzheimer's disease and Huntington disease.

In order to gain insight into normal and abnormal brain iron transport, metabolism and function, our approach was to map the gene for HSS. A primary genome scan was performed using samples from a large, consanguineous family (HS1) (see Fig. 1). While this family was immensely powerful for mapping, the region demonstrating homozygosity in all affected members spans only 4 cM, requiring very close markers in order to detect linkage. The HSS gene maps to an interval flanked by D20S906 and D20S116 on chromosome 20p12.3-p13. Linkage was confirmed in nine additional families of diverse ethnic backgrounds.

Using homozygosity mapping in a large Amish family, Taylor et al. (1996, 1996) mapped the disorder to 20p13-p12.3. Analysis of 9 other families from New Zealand, Australia, Spain, and Italy supported linkage to this region with a total maximum 2-point lod score of 13.75 at theta = 0.0 for 1 polymorphic microsatellite marker. Homozygosity in the Amish family and recombinant haplotypes in 3 of the other families suggested that the gene involved is located in a 4-cM interval between D20S906 and D20S116. Taylor et al. (1996) found locus heterogeneity for HSS; one Japanese family did not show linkage to this region, indicating the existence of another locus for the disorder.

Taylor et al. (1996) suggested that this disorder should be referred to as neurodegeneration with brain iron accumulation (NBIA1) to avoid the objectionable eponym -- Hallervorden promoted euthanasia in Germany during World War II.

Known Genes on Chromosome 20 (short arm)
near HSS and prion genes
OMIMDiseaseGene
171400 Multiple Endocrine Neoplasia, Type Ii Men2
112261 Bone Morphogenetic Protein-2 Bmp2
600810 Phospholipase C, Beta-4 Plcb4
176740 Proliferating Cell Nuclear Antigen Pcna
118450 Cholestasis With Peripheral Pulmonary StenosisCPPS
104760 Amyloid Beta A4 Precursor Protein App
176640 Prion Protein Prnp
234200 Hallervorden-Spatz Disease NBIA1
192340 Arginine Vasopressin Avp
139190 Growth Hormone-releasing Factor Ghrf
188040 Thrombomodulin Thbd
167050 Oxytocin--neurophysin I Oxt
176884 Protein-tyrosine Phosphatase, Lrp
131340 Enkephalin B EnkB

By analysis of interstitial 20p deletions, Schnittger et al. (1992) demonstrated for the prion gene the following order of loci: pter--PRNP--SCG1 (118920)--BMP2A (112261)--PAX1 (167411)--cen. Puckett et al. (1991) identified 5-prime of the PRNP gene a RFLP that has a high degree of heterozygosity, which might serve as a useful marker for the pter-p12 region of chromosome 20.

July 4 JBC:

Heidrun Deissler, Matthias Wilm, Bulent Genc, Birgit Schmitz, Thomas Ternes,
               Frauke Naumann, Matthias Mann, Walter Doerfler 
            Rapid protein sequencing by tandem mass spectrometry and cDNA
            cloning of p20-CGGBP. A novel protein that binds to the unstable
            triplet repeat 5{prime}-d(CGG)n-3{prime} in the human FMR1
            gene. 
            1997 272: J. Biol. Chem. 1997 July 4 272(27). 16761. 

      Albino Bacolla, Robert Gellibolian, Miho Shimizu, Sorour Amirhaeri, Seongman Kang,
      Keiichi Ohshima, Jacquelynn E. Larson, Stephen C. Harvey, B. David Stollar, Robert
      D. Wells 
            Flexible DNA: genetically unstable CTGCAG and CGGCCG from
            human hereditary neuromuscular disease genes 
            1997 272: J. Biol. Chem. 1997 July 4 272(27). 16783. 

      Robert Gellibolian, Albino Bacolla, Robert D. Wells 
            Triplet repeat instability and DNA topology: an expansion model
            based on statistical mechanics 
            1997 272: J. Biol. Chem. 1997 July 4 272(27). 16793. 

      Keiichi Ohshima, Robert D. Wells 
            Hairpin formation during DNA synthesis primer realignment in
            vitro in triplet repeat sequences from human hereditary disease
            genes 
            1997 272: J. Biol. Chem. 1997 July 4 272(27). 16798. 

Alternative usage of exon 1 of bovine PrP mRNA

Biochem Biophys Res Commun 233 (3): 650-654 (Apr 28 1997) 
Horiuchi M, Ishiguro N, Nagasawa H, Toyoda Y, Shinagawa M
Here we report two types of bovine prion protein mRNA that possessed different lengths of the 5'-untranslated region and were expressed in various bovine tissues. The two mRNA species were transcribed from identical positions but differed in the usage of the splice site for exon 1/intron. One mRNA possessed exon 1 consisting of 53 nucleotides and the other possessed exon 1 consisting of 168 nucleotides. Usage of exons 2 and 3 was identical for the two mRNA species. The two mRNA species were detected in all but spleen tissue; the mRNA possessing 168-nt exon 1 was not detected in bovine spleen.

This is the first report on the tissue-specific alternative splicing of prion mRNA in any species. Only a low level of PrPc appeared to be present in bovine spleen. These results suggested the possibility that the mRNA possessing 53-nt exon 1 was inefficiently translated into Prp; however, in vitro translation analysis showed no marked difference in translational efficiency between the two mRNA species.

The splice sites involved [webmaster, from GenBank]:

exon 1 (53 nucs)
gccagtcg ctgacagccg cagagctgag agcgtcttct ctctcgcaga agcag 

intron 1 (first 125 nucs)
gtaaa tagccgcgta gtcctttaaa ctcccagcgg aggacgccaa 
ccctgggtct tgcggccgag gcccagggac ccagccgaat cggattggtg
ggaggcagac cttgaccgtg agtagggctg intron 1 (last 50 nucs) ttaaata atccgttctt agatttatca attatagttt tttctttttt ttttaag exon 2 (first 23 nucs) gac ttctgaatat atttgaaaac

The psychiatric manifestation of CJD

Kao Hsiung I Hsueh Ko Hsueh Tsa Chih 13 (4): 263-267 (Apr 1997)
Yen CF, Lin RT, Liu CK, Lee PW, Chen CC, Chang YP
Creutzfeldt-Jakob disease (CJD) is considered to be very rare in the population, and the psychiatric manifestation of the disease even rarer with only one report in the past few years in Taiwan. To clarify whether the psychiatric manifestation of CJD is really rare or whether it is neglected in Taiwan, the authors reviewed the discharge notes of patients who had been admitted to a neurological unit in the past 15 years and conducted a chart review of the patients of CJD supported by the clinical courses, EEG finding and brain biopsies.

An inquiry was made by telephoning their families to follow up their condition after discharge. Five of the 8 cases with CJD had psychiatric symptoms including changes of mood, thought, behavior and perception during their course of illness. Four cases had been sent to the psychiatric unit and received treatment under several kinds of psychiatric diagnoses. Two patients had been admitted to the psychiatric unit and one had received electroconvulsive treatment.

Two of the patients had been suspected to be the victims of neuroleptic malignant syndrome. It is likely that it is psychiatrists who will meet CJD patients first in the early stages of disease. CJD should be kept in mind and EEGs with detailed neurological checkups should be completed, if the cognitive functions of the patients with unusual neurological symptoms deteriorate quickly and their psychiatric symptoms fail to respond to any treatment.

CJD after extracranial dura mater embolization for a nasopharyngeal angiofibroma.

Neurology 48 (5): 1451-1453 (May 1997) 
Antoine JC, Michel D, Bertholon P, Mosnier JF,... Veyret C
We report a 25-year-old man with Creutzfeldt-Jakob disease (CJD) who had received dura mater embolization in the external carotid artery for a nasopharyngeal angiofibroma 90 months earlier. The patient was heterozygotous (Met/Val) at codon 129. This case suggests that dura mater embolization can be responsible for the CJD.

Prion allotypes which accumulate in sporadic and familial CJD.

>Nat Med 3 (5): 521-525 (May 1997)
Silvestrini MC, Cardone F, Maras B, Pucci P, Barra D, Brunori M, PocchiariM
In the brain of patients heterozygous for isoleucine substituted for valine at codon 210 (Val 21O lle), PrP-res is formed by both the wild-type and mutant PrP-sen. We also found that in a sporadic CJD patient, who was heterozygous (Met/Val) at position 129, PrPres is also formed by both allotypes.

Alpha 1 anti-chymotrypsin signal peptide polymorphism in sporadic CJD

Neurosci Lett 227 (2): 140-142 (May 16 1997)
Salvatore M, Seeber AC, Nacmias B, Petraroli R, Sorbi S, Pocchiari M
In Creutzfeldt-Jakob disease (CJD), a transmissible spongiform encephalopathy, the deposition of the pathological prion protein (PrP-res) in the brain of affected individuals is the key event that triggers the appearance of the disease. Since a polymorphism in the signal peptide of the serine-protease inhibitor alpha1 antichymotrypsin (ACT) is one of the factors that may enhance amyloid formation, we studied this polymorphism in 63 CJD patients and 103 control subjects. No difference in allele frequencies and genotype distribution was found between CJD cases and controls, nor any difference was found between the ACT genotype and the age at onset and disease duration. Interestingly, there was a significantly different (P = 0.04) ACT distribution between CJD patients and controls in apolipoprotein E (ApoE) E4, and the interaction between ACT and ApoE was almost significant (P = 0.053). Further studies on a larger number of patients will clarify whether this association can identify a possible risk factor for CJD.

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