Neurochemical Research, Vol. 17, No. 6, 1992, pp. 591-597

BC200 RNA in Normal Human Neocortex, Non-Alzheimer Dementia (NAD), and Senile Dementia of the Alzheimer Type (AD) W. J. Lukiw 1, P. Handley 1, L. Wong l, and D. R. Crapper McLachlan I (Accepted November 4, 1991) BC200 RNA is a polyadenytated 200 nucleotide primate brain-specific transcript with 80% homology to the left monomer of the human Alu family of repetitive elements. Whether this transcription product contributes anything to normal brain gene function or is a residue of post transcriptional processing of brain heterogeneous nuclear RNA (hnRNA) is uncertain. However, the high abundance, tissue-specific expression and nucleotide sequence characteristics of BC200 RNA suggests that the generation of this small RNA is associated with some brain ceil function. Sustained levels of the BC200 RNA transcript may be indicative of a genetically competent and normally functioning cerebral neocortex. In this investigation, we have measured the abundance of the BC200 RNA transcript in total RNA isolated from 18 temporal neocortices (Brodman area 22) of brains with no pathology and those affected with neumdegenerative disease. Neocortiees were examined from 3 neurologically normal brains, 5 non-Alzheimer demented [NAD; 3 Huntingtons chorea (HC), 1 amyotrophic lateral sclerosis (ALS) and 1 dementia unclassified] and 10 Alzheimer disease (AD) affected brains. Our results indicate a strong BC200 presence in both the normal brains and NAD affected neocortices, but a 70 per cent reduction in BC200 signal strength in AD afflicted brains. These results may be related to the observation that Alzheimer brains exhibit marked deficits in the abundance of neuronspecific DNA transcripts; these deficits are consistent with the idea that AD is characterized by an impairment in the primary generation of brain gene transcription products. KEY WORDS: ALU repetitiveelement;Alzheimer'sdisease; BC200; brain gene regulation;brain transcription; neurodegenerativedisease.

INTRODUCTION

of DNA transcription products to maintain brain structure and function. The striking complexity of brain-specific gene expression raises fundamental questions as to the regulation of transcription of this large amount of genetic information. BC200, Alu Sequences, and Transcriptional Control After the discovery that a large proportion of the eukaryotic genome exists as repeated sequences, it was hypothesized that transcripts of repetitive elements acting as "activator RNAs" could coordinate or regulate the tissue-specific transcription of functionally related genes (4). One more recent model that has emerged to

Gene Expression in Mammalian Brain. Normally functioning mammalian brains generate both qualitatively and quantitatively more complex populations of RNA when compared to other somatic tissues or organs (1-3). This substantial transcriptional output of genetic information suggests that neural cells require large pools Center for Research in Neurodegenerative Disease, Tanz Neuroscience Building, University of Toronto, Toronto M5S 1A8, CANADA.

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Lukiw, Handley, Wong, and Crapper McLachlan

explain the control of gene expression in brain cells suggests that activation of brain identifier (ID) repetitive sequences, which occur within introns of genes transcribed by RNA Polymerase II (Pol II), may be important in the regulation of neuronal gene transcription (2). One of many primate ID-like transcripts so far described is BC200, a 200 nucleotide brain cytoplasmic RNA which hybridizes to total RNA isolated from human and monkey brain cells but not to total RNA isolated from rat or rabbit brain or to non-neural monkey tissues such as liver, spleen, heart, kidney, colon or skeletal muscle (5,6; this laboratory, unpublished observations). The abundance and brain specificity of this element, containment of RNA polymerase III (Pol III) A and B boxes, and the position of the 5' terminus of the BC200 RNA relative to the internal RNA Pol III A box (Figure 1) suggests that this transcript is the result of RNA Pol III gene transcription. In one model, Pol III transcription of ID elements might enhance or otherwise modulate transcription by RNA Polymerase II (Pol II) by initially "loosening up" local chromatin structure to permit

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Fig. 1. DNA Sequences in the Left Monomer of the Human ALU Repeat Family are Homologous to the Brain-Specific BC200 RNA Transcript, Homology matrix comparison of the human Alu repeat pBlur8 (23) plotted on the abscissa and the BC200 primate brainspecific sequence (5) plotted on the ordinate. Box A and B = RNA polymerase III split promotor (29); . . . . . AT rich sequences. Arrows demarcate Alu LM and Alu RM = Alu left and right monomer respectively (21,29). The BC200 sequence shows approximately 80 percent homology to this member of the Alu repetitive family (5).

expression of brain-specific genes (7). Of interest is that BC200 RNA is approximately 80% homologous to the left monomer of one Alu family member of repetitive elements (the Alu LM of the pBlur8 clone; Figure 1; 5); these are also located within introns of genes transcribed by RNA Pol II (8-10). The recent observation that the 300,000-900,000 copies-per-haploid-genome of the primate Alu family actually exists as a number of discrete subsets of related sequence (8,9) indicates that certain transcribed subsets of Alu members may be associated with cell or tissue-specific gene expression (10). For example, eight Alu sequences are located within the human globin gene cluster and small RNA transcripts homologous to an Alu member upstream of the human Eglobin gene are found only in cells where this gene is active (11). It remains unclear, however, whether such small RNA transcripts are the cause or the effect of RNA Pol II transcription. Since many Alu sequences are known to be coincidentally transcribed during the generation of heterogeneous nuclear RNA (hnRNA) by RNA Pol II, the presence of BC200 RNA may be only a consequence of the post-transcriptional processing of hnRNA transcripts. Alzheimer's Disease and Gene Expression. Alzheimer's disease involves the progressive degeneration of large neocortical neurons in the human cerebral cortex, and especially of pyramidal layers III and V, with accompanying deficits in normal nuclear function. The large size of these pyramidal nuclei, their extensive euchromatization and exceedingly high transcriptional output may make these brain cell types especially susceptible to the Alzheimer insult. Alzheimer specific changes are characterized by an increase in chromatin compaction of neocortical nuclei (12,13) and a marked reduction in both polyadenylated RNA (14) and brain-specific messenger RNA populations (15-17). Although the relationship between chromatin structure and selective gene expression is poorly understood, the direct correlation of increased chromatin condensation and reduced transcription of important brain genes in Alzheimer affected neocortex suggests a cause-andeffect relationship. As an index of the transcriptional competence of neocortical cells, we have quantitated, in 18 human brains, the level of BC200 RNA and compared it to the levels of the human light chain neurofilament (HNF-L) RNA which is neuron specific, glial fibrillary acidic protein (GFAP) RNA which is glial specific, beta-actin RNA message, a cytoskeletal microfilament common to both neurons and glia, and the Alu repetitive element (17). These 5 DNA transcripts are particularly abundant in the neocortices of normal human brain (17,18).

B C 2 0 0 R N A in Human Brain Neocortex

EXPERIMENTAL

593

PROCEDURE

Brain Tissues.Human brain tissues, listed in Table I, were kindly provided by the Canadian Brain Tissue Bank, Toronto, Canada. Post mortem intervals (death to brain freezing intervals) were 7.8 --- 5.7 hours for the control group and 5.4 - 3.6 hours for the AD group. Differences were not statistically significant between the two groups (p = 0.2139). At autopsy, brains were bisected in the sagittal plane; one half was fixed in buffered formalin for histopathological examination and the other half was frozen at - 90~ for nucleic acid analysis. On the basis of extensive histopathological evaluations one group of 3 brains, without neuropathological changes, was selected as normal controls with a mean patient age of 68.0 +- 23.4 years and a mean brain weight of 1255.0 +_ 77.8 grams. Similarly, 5 brains with no neuropathological changes in the temporal lobe neocortex was selected as a non-Alzheimer dementia (NAD) group with a mean age of 61.2 - 13.5 years and a mean brain weight of 1252.0 _+ 336.1 grams. Ten brains exhibiting classical Alzheimer histopathology of high senile plaque density and extensive neurofibrillary tangles in the temporal neocortices were selected with a mean patient age of 77.0 -+ 8.1 years and a mean brain weight 1141.2 _+ 191.1 grams (Table I). RNA Isolation and Northern (RNA) Gel Blots. Ultrapure reagents and restriction endonucleases of the highest commercially available grade were used throughout these experiments. Temporal neocortices were dissected in the frozen state upon a glass plate cooled to -45~ to minimize RNA degradation (19). Further, 10 mM PMSF (Sigma) and 1 U/~xL human placental ribonuclease inhibitor (RNasin; Promega Biotec) were employed in the extraction medium to inhibit both serine protease and specific RNase activities. Total RNA was isolated and quantitated using the methods described by Guillemette et al. (14) and was separated at 4~ on 1.5% agarose-2.2 M formaldehyde gels at 60 V for 4-5 hr with recirculating 20 mM sodium phosphate buffer, pH 7.0. 0.5, 1.0 and 1.5 ~g of total brain neocortical RNA were dot

blotted onto duplicate sets of Biotrans 0.45 Ixm hybridization membranes (ICN Corporation) by methods previously described (17,20). Preparation of Probes and Radiolabeling. The clone pMB12, kindly provided by J. Watson, Research Institute of Scripps Clinic, California, containing the monkey BC200 cDNA, was digested with the restriction enzymes Pstl and EcoRI (BRL; within the pUC18 vector polylinker region) to release the cDNA insert. Similarly, clone pBlur8, kindly provided by R. Chan, Department of Microbiology, University of Toronto, containing a human genomic Alu repetitive element (21), was digested with EcoRI (BRL) to liberate the Alu insert. The probes for HNF-L, GFAP and beta-actin were prepared as previously described (18). Electropurified inserts were radiolabeled to specific activities of 108 cpm 32p-labeled dCTP per Ixg of DNA employing an oligotabeling system (BRL Random Primer Kit; 22). Membranes, prepared in duplicate, were prehybridized for 8 hours, hybridized for 24 hours at 42~ and washed to both low and high stringencies (17). Quantitative autoradiography was performed at -81~ for 18 hours using two Dupont Cronex Quanta III intensifying screens and Fuji Xray film or without screens using Kodak X-omat AR-5 film. Autoradiographic signals were analyzed using a Hoefer GS300 scanning densitometer and an IBM-XT supported Hoefer GS350 data integration system. Alternately, to obtain quantitative hybridization signals, a qualitative autoradiogram was laid over the radioactive membrane surface on a light box, appropriate areas of the membrane were excised and counted in scintillation fluid. Differences in signal intensities were quantified by analysis of variance (ANOVA) using a MICROSTAT/ IBM statistics program (Ecosoft, Inc.).

RESULTS Figure 1 shows a homology matrix between BC200 c D N A a n d the h u m a n A l u s e q u e n c e f r o m c l o n e p B l u r 8

Table I. Human Brains Used in This Investigation

Normal N=3 NAD N=5

Alzheimer N=10

Patient Case No.

Age

PMI (hrs)

Sex

Brain Weight (grams)

*K635 K647 *K645 *K587 K639 K649 *K671 *K633 K594 K573 *K584 *K585 *K626 *K627 K638 K650 K658 *K661

81 41 82 58 57 45 64 82 70 70 87 81 92 82 68 73 72 75

9 3 5 14 15 13 1 2 4 5 3 4 5 2 3 12 12 4

M M M M M M M F F M F M F M M M F M

1200 1310 NA 1180 1650 800 1510 1120 1000 1400 1240 1175 730 1250 1022 1095 1180 1320

Cause of Death cerebrovascular accident motor vehicle accident lung carcinoma Huntington's chorea Huntington's chorea Huntington's chorea amyotrophic lateral sclerosis unclassified dementia Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease Alzheimer's disease

Age = age in years at time of death. NA = data not available. PMI = postmortem interval in hours. Asterisks = total brain RNA displayed in Figures 2 and/or 3. NORMAL + NAD brains comprised the CONTROL group.

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Lukiw, Handley, Wong, and Crapper McLachlan

(21,23). Note that BC200, approximately 80% homologous to the Alu LM, gives a correspondingly diminished signal strength when compared to the entire Alu repeat as determined by molecular probe hybridizations [(0.8 x 0.5 x 73%) - 30%; Table IIA). This would be expected due to the nature of the random priming chemistry used (22), which incorporates at every position complimentary to guanosine on the newly synthesized strand a radiolabeled cytosine. To this end, BC200 and the pBlur8 human Alu sequence have comparable cytosine contents (pBlur8, 17.8%; BC200, 15.5%; 5,23). Figure 2 shows Northern dot blot analyses for 4 controls and 3 AD total neocortical RNA samples (1.0 txg) probed with BC200, HNF-L, GFAP, beta-actin and the Alu repeat sequence and is representative of the control and AD total RNA analysed in these experiments. We consistently observe a markedly diminished RNA signal for both BC200 and HNF-L in AD tissue when compared to the RNA signal for beta-actin, GFAP or the Alu repetitive sequence. Based on duplicate experiments for 3 different load-

Table IIA. RNA Pool Size Based on Total Signal Strength, Percent Alzheimer Controland Statistical Significance

DNA Probe GFAP beta-actin Alu element(pBlur8) HNF-L BC200

Based on Total RNA

Statistical Significance (ANOVA)

125 106 73 33 30

NS NS NS 0.001 0.001

GFAP = glial fibrillaryacidic protein; HNF-L = human neurofilament light chain gene; NS = not significant.ANOVA = Analysisof Variance. Basedon analysisof 18 humanbrain neocortices,Brodmann Area 22.

Table IIB. BC200 Signal Strengthas hnRNA or Discrete200 NucleotideSpecies RATIO hnRNA/200 hnRNA 200 nucleotide nucleotide N SPECIES SPECIES SPECIES Control Alzheimer ANOVA (p) Alzheimer Contml

8 100.0 10 32.7 0.0006 0.327

65.9 21.2 0.0017 0.322

1.52 1.54 0.616

Means of Relativesignal strengthbased on controlhnRNAspecies = 100.0. ANOVA = analysis of variance. N = numberof individual brains used, see Table I; Control = Normal + NAD. Alzheimer/ Control = ratio of the means.

ings of total neocortical RNA, Table IIA describes the RNA message abundance for GFAP, beta-actin, the Alu repetitive element, HNF-L and BC200 RNA in the temporal neocortices of 8 control and 10 AD brains. In previous studies (14,17), both total and specific messenger RNA yields from the neocortex of brains affected with HC and ALS were found not to be significantly different from normal neocortical RNA yields and were grouped together as control brains. Notably, in these experiments, the neocortices from the HC, ALS and unclassified dementia cases exhibited no abnormal histopathology. Statistical analysis revealed no difference between the healthy control and NAD cases in BC200 content and these data were combined. The trends for moderately elevated signal strength for GFAP and beta-actin messages may be the result of glial proliferation in AD affliated neocortex since these cytoskeletal transcripts are abundant both in oligodendroglia and neuroglial cells (24). The reduction in Alu RNA signal in AD, to 73% of the control value, suggests an impairment in the generation of primary transcription products in AD since this repetitive element is often found in the 5' leaders, 3' trailers and within introns of primary DNA transcripts, i.e. hnRNA (10,21). HNF-L, a single copy neuron-specific gene, has been shown by several investigators to be reduced to at least 33% of the age matched control levels in AD afflicted neocortices (15-18). Table IIB describes the BC200 signal strength as it occurs in hnRNA or as a discrete 200 nucleotide species for control and AD afflicted neocortices. In both control and AD, approximately 65 per cent of the hnRNA signal (control 65.9%; AD 64.8%) appears as the 200 nucleotide BC200 signal suggesting that while equivalent states of primary transcript signal processing occurs in both control and AD, there is an impairment in primary transcription product generation in AD afflicted brain. Since BC200 signal strength was not found to be statistically different between age matched normal and NAD neocortices, it is likely that this decrease is specific to AD afflicted tissue. Figure 3 shows a representative autoradiogram of several total brain RNA samples from Table I run out on short gels, Northern transferred and probed with BC200. Note the general reduction in BC200 signal strength in AD (ALZ) but not in ALS, HC or normal (CONT) brains. This decrement is not attributable to age, sex, agonal process or post mortem influences since the selection of critically matched brains gave similar results. For example, the control (K645) and ALZ 3 (K627) cases of Figure 3 were both 82 year old males and ALZ3 had a 3 hour shorter post mortem interval (5 hours versus

BC200 RNA in Human Brain Neocortex

595

Fig. 2. RepresentativeNorthern Dot Blots of BC200 RNA, HNF-L, GFAP,beta-actin and the ALU RepetitiveSequencefrom HumanCerebral Cortex. The dotsrepresent the hybridizationsignal,for the probes indicated,from 1 Ixgtotal RNA extractedfromcontrolor AD affectedneocortex. For completedescriptionof brain tissuesused refer to TABLEI.

2 hours). Brain atrophy is also not accountable for these deficits since HC case K587, an 1180 gram brain, gave a stronger BC200 hybridization signal than K584, a 1240 gram AD case (Table I; Figure 3; unpublished data). Notably, total human placental RNA (PLA) reveals a hybridization signal in the hnRNA but no free BC200 signal, while rabbit brain shows no detectable BC200 signal in the total RNA isolated unless lower hybridization stringencies were used (data not shown). These results support the contention that the BC200 RNA signal is derived from a brain hnRNA pool and that this transcript is associated only with total RNA isolated from primate brain (5).

DISCUSSION The mammalian brain expresses substantially more genetic information than other non-neural cells and tissues (1,25). Moreover, complex brain functions, such as the formation and maintenance of a dynamic neuronal cytoarchitecture, depend upon the concerted activities of

a group of genes which are often non-linked, i.e. the single copy HNF-L gene on chromosome 8 (26) and the HNF-H (heavy chain) gene on chromosomes 1 and 22 (27). The coordinated expression of such gene batteries might be mediated by a common trans-acting factor, regulatory DNA sequence, an ID-like DNA sequence or some related repetitive element shared by each of these genes. The BC200 RNA may represent one such brain regulatory element. Alternatively, this relatively abundant RNA may only be a remnant of processed hnRNA through intron removal from Pol II generated hnRNA transcripts in the brain. Whatever the exact role of BC200 RNA, steady state levels of this small RNA transcript may be a marker for normal brain genomic activity. In AD affected neocortex, but not in NAD or normal controls, statistical analyses revealed that there was a deficit in BC200 signal strength in both hnRNA and freely migrating BC200 to approximately 32% of control values (p = 0.0006 and 0.0017, respectively; Table IIB and Figure 3). Because hnRNA and BC200 levels decrease in a parallel fashion both in controls and in AD affected neocortex, this suggests that BC200 RNAs are

596

HUMAN CEREBRAL CORTEX B C 2 0 0 RNA YIELD

Lukiw, Handley, Wong, and Crapper McLachlan rich neurofibrillary tangles, also reveal the presence of epitopes to normal neurofilaments (28). Non stoichiometric gene expression of the neurofilament triplet or altered expression of one member of this gene family has been suggested to lead to the formation of the abnormal cytological inclusions in the diseased neuron (18). The observed correlation between reduced levels of BC200 RNA and the HNF-L transcript from temporal neocortical areas consistently affected in AD suggests that the attenuation of transcription of genes normally expressed at high levels in the brain might play a role in the etiopathogenesis of this common neurodegenerative disorder.

ACKNOWLEDGMENTS

Fig. 3. BC200 Yield from Human Cerebral Cortex. The radiolabeled brain-specific BC200 ID sequence was hybridized to total RNA from control (CONT; K645, 82 yr), amyotrophic lateral sclerosis affected (ALS, K671, 64 yr), Alzheimer affected (ALZ1 = K626, 92 yr; ALZ2 = K584, 87 yr; ALZ3 = K627, 82 yr.), Huntington's chorea (H. Chorea, K587, 58 yr) affected cerebral cortex, human placenta (PLA) and total rabbit brain (RAB). Gel migration is from left to right (O = origin). The heterogeneous nuclear RNA (hnRNA) ranges in size from about 5-11000 nucleotides in this gel. Note reduction both in hnRNA and BC200 signal strength in Alzheimer affected brain.

derived from a large hnRNA transcript pool and that a deficit in the initial generation of the transcription product, rather than an impairment of hnRNA processing to free BC200 RNA, occurs in AD afflicted brain. These findings correlate with the observations that AD brains show generalized deficits in several different cytoskeletal mRNA signal strengths (Table IIA; 15, 19), with the largest deficiencies occurring in RNA messages coding for neuron-specific transcription products (16-18). Neurofilament metabolism is severely perturbed in AD, as reflected by the large reduction in the expression of the neuron specific HNF-L gene (15-17). This reduced yield of RNA message for HNF-L cannot be adequately accounted for by an increase in HNF-L RNA message degradation (18), by non specific responses to brain damage nor to loss of a subclass of neurons with neurofibrillary degeneration (17). Abnormal cytopathological inclusions characteristic of AD, such as the tau

Thanks are extended to Drs. J. B. Watson and J. G. Sutcliffe, Scripps Clinic, for providing the BC200 eDNA, and to Drs. I. R. Brown and M. K. Sutherland, University of Toronto, for helpful suggestions and critical reading of the manuscript. Normal and pathological tissues were kindly supplied by the Canadian Tissue Brain Bank, Toronto, Canada. Thanks are extended to Drs. C. Bergeron and J. Deck, Division of Neuropathology, Toronto General Hospital, for neuropathological evaluations. This research was supported by the Ontario Mental Health Foundation, the National Science and Engineering Research Council of Canada (NSERC), the Alzheimer Society of Canada and the Medical Research Council of Canada.

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BC200 RNA in Human Brain Neocortex 11. Allan, M., and Paul, J. 1984. Transcription in vivo of an Alu family member 5' to the human E-globin gene. Nucl. Acids Res. 12:1193-1200. 12. Crapper McLachlan, D. R., Lewis, P. N., Lukiw, W. J., Sima, A., Bergeron, C., and De Boni, U. 1984. Chromatin structure in dementia. Ann. Neurol. 15:329-334. 13. Bachelard, H. S., Hodder, V.E., and Walker, A. P. 1986. DNA damage and repair in Alzbeimer's disease. Mod. Trends Aging Res. 147:451-458. 14. Guillemette, J. G., Wong, L., Crapper McLachlan, D. R., and Lewis, P. N. 1986. Characterization of messenger RNA from the cerebral cortex of control and Alzheimer afflicted brain. J. Neurochem. 47:987-997. 15. Kittur, S., Hoh, J., Kawas, C., Tourtellotte, W., Markesbury, W., and Adler, W. 1990. Neurofilament gene expression in Alzheimer's disease. Abstract 135. Second International Conference on Alzheimer's Disease. Neurobiology of Aging 11:285-286. 16. Clark, A. W., Krekoski, C. A., and Parhad, I. 1989. Altered expression of genes for amyloid and cytoskeletal proteins in Alzheimer cortex. Ann. Neurol., 25:331-339. 17. Crapper McLachlan, D. R., Lukiw, W. J., Wong, L., Bergeron, C., and Bech-Hansen, N. T. 1988. Selective messenger RNA reduction in Alzheimer's disease. Mol. Brain Res. 3:255-262. 18. Lukiw, W. J., Wong, L., and McLachlan, D. R. 1990. Cytoskeletal messenger RNA stability in human neocortex: studies in normal aging and in Alzheimer's disease. Intern. J. Neuroscience 55:81-88. 19. Taylor, G. R., Carte, G. I., Grow, T. J., Johnson, T. J., Fairbairn, J. A., Perry, E. K. and Perry, R. H. 1986. Recovery and measurement of specific RNA species from postmortem brain tissue: A general reduction in Alzheimer's disease detected by molecular hybridization. Exptl. and Molec. Pathol. 44:111-116.

597 20. Thomas, P. S., 1980. Hybridization of denatured RNA and small DNA fragments transferred to nitrocellulose. Proc. Natl. Acad. Sci. USA 77:5201-5205. 21. Schmid, C. W., and Jelinek, W. R. 1982. The Alu family of dispersed repetitive sequences. Science 216:1065-1070. 22. Feinberg, A. P., and Vogelstein, B. 1983. A technique for labeling DNA restriction fragments to high specific activity. Anal. Biochem. 132:6-13. 23. Bains, W. B. 1986. Multiple origins of human Alu sequence. J. Mol. Evolution 23:189-199. 24. Lazarides, E. 1982. Intermediate filaments. Ann. Rev. Biochem. 51:219-250. 25. Kaplan, B. B., Gioio, A. E., Capano, C. P. and Giuditta, A. 1986. A comparative study of the diversity of gene expression in brain. Pages 1-9 in Giuditta, A., (ed.), The Role of RNA and DNA in brain function, Martinus Nijhoff Publishing, Boston. 26. Julien, J. P., Grosveld, F., Yazdanbaksh, K., Flavell, D., Meijer, D., and Mushynski, W. 1987. The structure of a human neurofilament gene (NF-L); a unique exon-intron organization in the intermediate filament gene family. Biochim. et Biophysica Acta. 909:10-20. 27. Mattei, M. G., Dautigny, A., Pham-Dinh, D., Passage, E., Mattel, J., and Jolles P. 1988. The gene encoding the large human neurofilament subunit (NF-H) maps to the q121-q131 region on human chromosome 22. Hum. Genet. 80:293-295. 28. Chin, S. S. M., and Liem, R. K. 1987. Neurofilaments: A review and an update. In G. Perry, Alterations in The Neuronal Cytoskeleton in Alzheimer's Disease, Advances in Behavioral Biology Vol. 34. Plenum Press, New York. 29. UUu, E. 1982. The human Alu family of repeated DNA sequences. Trends in Biochemical Sciences 82:216-219.

BC200 RNA in normal human neocortex, non-Alzheimer dementia (NAD), and senile dementia of the Alzheimer type (AD).

BC200 RNA is a polyadenylated 200 nucleotide primate brain-specific transcript with 80% homology to the left monomer of the human Alu family of repeti...
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