Discordance between traditional pathologic and energy metabolic changes in very early Alzheimer's disease. Pathophysiological implications

These results suggest that neither the loss of entorhinal efferents nor cholinergic deficit explains all the metabolic features seen in very early AD. Given recent immunohistological evidence of massive glutamatergic synaptic alteration in early AD cortex and insights into neuronal and glial mechanisms of glucose metabolism, very early metabolic changes in AD probably reflect a significant impairment of glycolytic activities in the cortico-cortical glutamatergic systems in a preclinical stage of the disease. However, the exact mechanisms of such impairment in these neurons are yet to be determined.

Progress in the clinical and molecular genetics of familial parkinsonism

Parkinson's disease (PD) is a neurodegenerative disease with clinical features resulting from deficiency of dopamine in the nigrostriatal system. Most PD cases are sporadic and the primary cause of the disease is still unknown. Recently, familial PD and parkinsonism have received much attention because these forms of the disease might provide clues to the genetic risk factors involved in the pathogenesis of idiopathic PD. To date, two causative genes, alpha-synuclein and the parkin gene, have been identified. alpha-Synuclein is involved in the pathogenesis of an autosomal dominant form of PD and constitutes a major component of the Lewy body, which is a pathological hallmark of idiopathic PD. In addition, mutations in the parkin gene have been identified as the cause of autosomal recessive juvenile parkinsonism (AR-JP). AR-JP manifests itself as a highly selective degeneration of the substantia nigra and the locus coeruleus, but without Lewy body formation. In addition to these two genes, four chromosomal loci have been linked to other forms of familial PD. Furthermore, there are a number of other pedigrees of familial PD in which linkage to known genetic loci has been excluded. Molecular cloning of these disease genes and elucidation of the function of their gene products will greatly contribute to our understanding of the pathogenesis of idiopathic PD.

Lasting cortical activation after repetitive TMS of the motor cortex: a glucose metabolic study

OBJECTIVE

Cerebral [18F]fluorodeoxy-D-glucose PET ([18F]FDG-PET) was used to visualize the lasting neuronal activation after repetitive transcranial magnetic stimulation (rTMS) over the left hand area of the primary motor cortex (M1HAND).

BACKGROUND

Applied over M1HAND, rTMS has been shown to produce a modulation of corticomotor excitability beyond the time of stimulation itself.

METHODS

Eight right-handed subjects underwent nonquantitative [18F]FDG-PET measurements during two experimental conditions: at rest and after focal subthreshold 5-Hz rTMS over the left M1HAND. In the post-rTMS condition, [18F]FDG was injected immediately after the administration of 1,800 magnetic pulses over the left M1HAND. Relative differences in normalized regional cerebral metabolic rate of glucose (normalized rCMRglc) between conditions were determined using a voxel-by-voxel Student's t-test and volume-of-interest (VOI) analysis. Analysis was a priori restricted to the M1HAND, the supplementary motor area (SMA), and the primary auditory cortex of both hemispheres.

RESULTS

A 5-Hz rTMS of the left M1HAND caused a lasting relative increase in normalized rCMRglc within the M1HAND bilaterally and the SMA. The magnitude and the topographic pattern of persisting relative rCMRglc increases within these motor cortical areas demonstrated considerable interindividual variations.

CONCLUSIONS

Subthreshold 5-Hz repetitive transcranial magnetic stimulation (rTMS) over the hand area of the primary motor cortex is associated with a persisting neuronal activation in a distinct set of motor cortical areas beyond the time of stimulation. The current findings demonstrate that [18F]FDG-PET can localize and quantify regional net changes in synaptic cortical activity after rTMS and thus might elucidate the mechanisms underlying rTMS-associated therapeutic effects.

Hox cluster genomics in the horn shark, Heterodontus francisci

Reconstructing the evolutionary history of Hox cluster origins will lead to insights into the developmental and evolutionary significance of Hox gene clusters in vertebrate phylogeny and to their role in the origins of various vertebrate body plans. We have isolated two Hox clusters from the horn shark, Heterodontus francisci. These have been sequenced and compared with one another and with other chordate Hox clusters. The results show that one of the horn shark clusters (HoxM) is orthologous to the mammalian HoxA cluster and shows a structural similarity to the amphioxus cluster, whereas the other shark cluster (HoxN) is orthologous to the mammalian HoxD cluster based on cluster organization and a comparison with noncoding and Hox gene-coding sequences. The persistence of an identifiable HoxA cluster over an 800-million-year divergence time demonstrates that the Hox gene clusters are highly integrated and structured genetic entities. The data presented herein identify many noncoding sequence motifs conserved over 800 million years that may function as genetic control motifs essential to the developmental process.

The myocilin (MYOC) gene expression in the human trabecular meshwork

PURPOSE

We previously reported a novel cytoskeletal protein with a myosin-like domain which is localized in the ciliary rootlet and basal body of connecting cilium of photoreceptor and hence we named it 'myocilin'. It was soon realized that myocilin is identical to a protein called TIGR (trabecular meshwork inducible glucocorticoid response protein) which was found to be responsible for the pathogenesis of juvenile open angle glaucoma. In this study, we employed in situ RNA hybridization to examine the myocilin (MYOC)/ TIGR gene expression in the trabecular meshworks of glaucomatous and nonglaucomatous eyes.

METHODS

The glaucomatous specimens were obtained by trabeculectomy from the patients with primary open angle glaucoma (POAG), chronic angle closure glaucoma (CACG) and steroid glaucoma, respectively, and the nonglaucomatous specimens were obtained from a victim of traffic accident at autopsy and from a patient with maxillary sinus carcinoma at enucleation for the operation. The in situ RNA hybridization was carried out with digoxigenin-labeled sense and antisense RNA probes.

RESULTS

In all cases, hybridization signals were detected primarily in the trabecular meshwork cells and secondarily in the fibroblast-like cells of corneoscleral wall.

CONCLUSIONS

Myocilin gene is expressed clearly in the trabecular meshwork cells of both glaucomatous and nonglaucomatous eyes.

Keio Mutation Database (KMDB) for human disease gene mutations

A database of mutations in human disease-causing genes has been constructed and named as Keio Mutation Database (KMDB). This KMDB utilizes a database software called MutationView which was designed to compile various mutation data and to provide graphical presentation of data analysis. Currently, the KMDB accommodates mutation data of 38 different genes for 35 different diseases which are involved in eye, heart, ear and brain. These KMDBs are accessible through http://mutview.dmb.med.keio.ac.jp with advanced internet browsers.

Eye disorder database "KMeyeDB"

The KMeyeDB (http://mutview.dmb.med.keio.ac.jp) has been developed as a database of mutations in human eye disorder genes using software called MutationView which provides graphical presentation of various data analysis. Here, we present several display windows from the KMeyeDB for data analysis of mutations in the RB-1 gene, which is responsible for the pathogenesis of retinoblastoma, a malignant tumor in the retina.

Identification of a putative regulatory subunit of a calcium-activated potassium channel in the dup(3q) syndrome region and a related sequence on 22q11.2

Duplication of a segment of the long arm of human chromosome 3 (3q26.3-q27) results in a syndrome characterized by multiple congenital abnormalities and neurological anomalies in some patients. We have identified a novel gene (KCNMB3) that maps to this region. KCNMB3 has significant sequence similarity to the regulatory subunit of the large-conductance calcium-activated potassium channel. Due to the significance of potassium channels in neuronal functions, the overexpression of this gene may play a role in the abnormal neurological functions seen in some of these patients. A related sequence corresponding to the second and third exons of this gene resides in the pericentromeric region of 22q11, where a number of other unprocessed pseudogenes are known to map.

Arterial/venous plasma nicotine concentrations following nicotine nasal spray

BACKGROUND AND OBJECTIVES

Arterial (A) and venous (V) plasma nicotine and cotinine concentrations were measured after nasal nicotine spray in tobacco smokers of both genders. The hypothesis for this research was that a greater A/V difference in plasma nicotine would be present in males than females because males have greater skeletal muscle mass to bind nicotine.

SUBJECTS AND METHODS

Nine male and nine female healthy adult smokers were studied. They all abstained from use of tobacco overnight for 10 h or more prior to the study. Nicotine nasal spray was given in doses of 1-2.5 mg total, with half in each nostril while the subject was supine. Both A and V blood samples were obtained prior to and 3, 6, 10, 15, 20, and 30 min post-nasal nicotine spray.

RESULTS AND CONCLUSIONS

Nasal nicotine administration produced greater A than V plasma levels. There were no gender differences in A/V nicotine concentrations, disproving the above hypothesis, suggesting that other physiochemical factors besides skeletal muscle mass must be involved. Heart rate increases correlated well with arterial plasma nicotine levels (r = 0.77). Males had less variance than females in the expected increase in arterial plasma nicotine concentrations with increased number of nasal sprays. Although there was considerable overlap, mean A cotinine concentrations were consistently slightly larger than V concentrations.

Striatal presynaptic monoaminergic vesicles are not increased in Tourette's syndrome

BACKGROUND

Abnormal function of striatal dopaminergic synapses is suggested to underlie Tourette's syndrome (TS).

OBJECTIVE

To determine dorsal striatal dopaminergic innervation in TS. Prior in vitro and in vivo studies of dopamine reuptake transporter binding sites suggest increased striatal dopaminergic innervation in TS.

METHODS

We used in vivo measures of striatal vesicular monoamine transporter type-2 (VMAT2) binding to quantify striatal dopaminergic innervation in TS. Eight TS patients (mean age 30+/-9 years) and 22 age-comparable normal controls (age 34+/-8 years) underwent PET imaging with the VMAT2 ligand (+)-alpha-[11C]dihydrotetrabenazine (DTBZ). Compartmental modeling was used to quantify blood-to-brain ligand transport and VMAT2 binding site density from the tissue-to-plasma distribution volume (DV) during continuous (+)-alpha-[11C]DTBZ infusion. DTBZ DV in dorsal striatal regions was expressed relative to the occipital cortex to estimate relative specific VMAT2 binding (binding potential).

RESULTS

We found no significant differences in VMAT2 binding potential between patients and controls in the caudate nucleus, anterior putamen, or posterior putamen. There were no significant differences in striatal VMAT2 binding between patients with (n = 5) or without (n = 3) features of obsessive-compulsive disorder.

CONCLUSIONS

There is no evidence for increased binding to the VMAT2 in TS striatum and that dorsal striatal dopaminergic innervation density is normal in TS. The previously reported changes in dopamine transporter binding sites may reflect medication effect and/or altered synaptic activity or regulation of dopamine transporter expression in nigrostriatal neurons.

Head and neck cancer: detection of recurrence with three-dimensional principal components analysis at dynamic FDG PET

Fully automated principal components analysis (PCA) was applied to dynamic 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomographic (PET) images obtained in 15 patients with previously treated head and neck cancer. PCA with time-activity curves incorporated kinetic information about FDG uptake, which improved tissue characterization on FDG PET images. The combination of standardized uptake value and PCA image sets likely will improve the reliability of tumor detection in head and neck cancers.

Immunohistochemical and subcellular localization of Parkin protein: absence of protein in autosomal recessive juvenile parkinsonism patients

Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical entity characterized by a selective degeneration of nigral neurons. Recently, the parkin gene responsible for AR-JP has been identified. Now, we report the subcellular localization of Parkin protein in patients with AR-JP or Parkinson's disease (PD) and in controls by immunoblotting and immunohistochemistry using antibodies raised against the Parkin molecule. Parkin protein was absent in all regions of the brains of patients with AR-JP. Parkin protein was not decreased in the brains of sporadic PD patients. Immunoreactivity was detected in a few Lewy bodies. Parkin protein was located in both the Golgi complex and cytosol.

18F-FDG PET studies in patients with extratemporal and temporal epilepsy: evaluation of an observer-independent analysis

The aim of this study was to evaluate an observer-independent analysis of 18F-fluorodeoxyglucose (FDG) PET studies in patients with temporal or extratemporal epilepsy.

METHODS

Twenty-seven patients with temporal epilepsy and 22 patients with extratemporal epilepsy were included in the study. All patients with temporal epilepsy and 7 patients with extratemporal epilepsy underwent surgical treatment. In patients who showed significant postoperative improvement (temporal, n = 23; extratemporal, n = 6), the epileptogenic focus was assumed to be located in the area of surgical resection. In extratemporal epilepsy patients who did not undergo surgery, the focus localization was determined using a combination of semiology, ictal and interictal electroencephalography, [99mTc]ethyl cysteinate dimer SPECT, MRI and [11C]flumazenil PET. Visual analysis was performed by two experienced and two less experienced blinded observers using sagittal, axial and coronal images. In the automated analysis after anatomic standardization and generation of three-dimensional stereotactic surface projections (SSPs), a pixelwise comparison of 18F-FDG uptake with an age-matched reference database (n = 20) was performed, resulting in z score images. Pixels with the maximum deviation were detected, summarized and attached to one of 20 predefined surface regions of interest. For comparison with 18F-FDG PET and MR images, three-dimensional overlay images were generated.

RESULTS

In patients with temporal epilepsy, the sensitivity was comparable for visual and observer-independent analysis (three-dimensional SSP 86%, experienced observers 86%-90%, less experienced observers 77%-86%). In patients with extratemporal epilepsy, three-dimensional SSP showed a significantly higher sensitivity in detecting the epileptogenic focus (67%) than did visual analysis (experienced 33%-38%, each less experienced 19%). In temporal lobe epilepsy, there was moderate to good agreement between the localization found with three-dimensional SSP and the different observers. In patients with extratemporal epilepsy, there was a high interobserver variability and only a weak agreement between the localization found with three-dimensional SSP and the different observers. Although three-dimensional SSP detected multiple lesions more often than visual analysis, the determination of the highest deviation from the reference database allowed the identification of the epileptogenic focus with a higher accuracy than subjective criteria, especially in extratemporal epilepsy.

CONCLUSION

Three-dimensional SSP increases sensitivity and reduces observer variability of the analysis of 18F-FDG PET images in patients with extratemporal epilepsy and is, therefore, a useful tool in the evaluation of this patient group. The benefit of this analytical approach in patients with temporal epilepsy is less apparent.

Polymorphism in the parkin gene in sporadic Parkinson's disease

We report polymorphism of the parkin gene in 160 sporadic Parkinson's disease (PD) patients and controls. Three polymorphisms were found: a G-to-A transition in exon 4 (S/N167), a C-to-T transition in exon 10 (R/W366), and a G-to-C transition in exon 10 (V/L380). Genotype distributions and allele frequencies of S/N167 and V/L380 did not differ significantly between the two groups. The R/W366 allele frequency was significantly lower in PD patients (1.2 vs 4.4%). The level of protection from PD provided by this allele was 3.60 (95% CI; range, 0.45-6.50), suggesting that it may be a protective factor against PD.

A 1.5-Mb contig within the cat eye syndrome critical region at human chromosome 22q11.2

We have constructed a 1.5-Mb contig spanning the distal half of the critical region for cat eye syndrome on human chromosome 22 from D22S543 to D22S181. The contig consists of 20 P1 artificial chromosome (PAC) clones and 11 bacterial artificial chromosome (BAC) clones screened from 2 BAC and 2 PAC libraries. Continuous overlap between the clones was confirmed using vectorette PCR and riboprobes. Despite the instability of this region in a previous YAC contig, only 1 BAC showed a minor instability and then in only one isolation. This contig is now providing the basis for genomic sequencing and gene identification in the cat eye syndrome critical region.

Brain activation in PTSD in response to trauma-related stimuli

BACKGROUND

Repetitive recall of traumatic memories and chronic intermittent hyperarousal are characteristic of posttraumatic stress disorder (PTSD). Hyperarousal and memory dysfunction implicates "limbic" brain regions, including the amygdaloid complex, hippocampal formation, and limbic cortex, such as the orbitofrontal and anterior cingulate areas. To investigate the neurobiologic role of these brain regions in PTSD, we measured regional cerebral blood flow in PTSD with single photon emission computerized tomography (SPECT) during a symptom provocation paradigm.

METHODS

Fourteen Vietnam veterans with PTSD, 11 combat control subjects, and 14 normal control subjects were studied with [99mTc]HMPAO in two sessions 48 hours apart: one session after exposure to white noise and the other following exposure to combat sounds. Skin conductance, heart rate, and subjective experience were recorded at the time of the studies.

RESULTS

Activation for all three groups occurred in the anterior cingulate/middle prefrontal gyrus. Activation in the region of the left amygdala/nucleus accumbens was found in PTSD patients only. Deactivation was found in all three groups in the left retrosplenial region.

CONCLUSIONS

These findings implicate regions of the "limbic" brain, which may mediate the response to aversive stimuli in healthy individuals and in patients suffering from PTSD.

[Focal segmental glomerulosclerosis associated with type C virus hepatitis and decrement of proteinuria by interferon-alpha therapy]

Focal segmental glomerulosclerosis (FSGS) associated with type C virus (HCV) hepatitis has not been described in the literature to date. However, we experienced a 30-year-old man, who had had HCV hepatitis, developed nephrotic syndrome and was admitted to our hospital. The first renal biopsy showed FSGS which was diagnosed by light, immunofluorescent, and electron microscopic study. FSGS diagnosis was based upon the findings of focal segmental glomerular sclerosis associated with hyalinosis and foam cells, segmental deposition of IgM and C3 on glomeruli, and epithelial cell vacuolization in the Bowman's space. HCV hepatitis was treated with interferon-alpha (INF-alpha) over 6 months. The treatment brought the disappearance of not only HCV-RNA from the blood, but also the manifestation of nephrotic syndrome. Therefore, the second renal biopsy was performed, but did not reveal any great pathological improvement. Five months later after the remission, he again had an elevated HCV-RNA level and a relapse of nephrotic syndrome. He was retreated with the same therapy and achieved a second remission of nephrotic syndrome. FSGS associated with HCV hepatitis is described first and the implication of INF-therapy in the improvement of proteinuria is discussed.

Organization of the gene for gelatin-binding protein (GBP28)

GBP28 is a novel human plasma gelatin-binding protein that is encoded by apM1 mRNA, expressed specifically in adipose tissue. Three overlapping clones (two lambda clones and one BAC clone) containing the human plasma gelatin-binding protein (GBP28) gene were isolated and characterized. The GBP28 gene spans 16kb and is composed of three exons from 18bp to 4277bp in size with consensus splice sites. The sizes of the two introns were 0.8 and 12kb, respectively. The gene's regulatory sequences contain putative promoter elements, but no typical TATA box. The third exon of this gene contains a long 3'-untranslated sequence containing three Alu repeats. The exon-intron organization of this gene was very similar to that of obese gene, encoding leptin. We also report the chromosome mapping of this gene by fluorescence in situ hybridization (FISH) using a genomic DNA fragment as a probe. The GBP28 gene was located on human chromosome 3q27. The nucleotide sequence data reported in this paper will appear in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession numbers ABO12163, ABO12164 or ABO12165.

In vivo mapping of cerebral acetylcholinesterase activity in aging and Alzheimer's disease

OBJECTIVE

To validate an in vivo method for mapping acetylcholinesterase (AChE) activity in human brain, preparatory to monitoring inhibitor therapy in AD.

BACKGROUND

AChE activity is decreased in postmortem AD brain. Lacking a reliable in vivo measure, little is known about central activity in early AD, when the disease is commonly targeted by AChE inhibitor drug therapy.

METHODS

Intravenous N-[11C]methylpiperidin-4-yl propionate ([11C]PMP) served as an in vivo AChE substrate. AChE activity was defined using cerebral PET for tracer kinetic estimates of the local rate of [11C]PMP hydrolysis in 26 normal controls and 14 patients with AD. Eleven AD patients also had concomitant in vivo cerebral measures of vesicular acetylcholine transporter (cholinergic terminal) density and glucose metabolism.

RESULTS

Cerebral AChE activity measures 1) were independent of changes in tracer delivery to cerebral cortex; 2) agreed with reported postmortem data concerning normal relative cerebral distributions, absence of large age-effect in normal aging, and deficits in AD; 3) correlated in AD cerebral cortex with concomitant in vivo measures of cholinergic terminal deficits, but not with metabolic deficits; and 4) agreed quantitatively with predicted level of cerebral AChE inhibition induced by physostimine.

CONCLUSIONS

This in vivo PET method provided valid measures of central AChE activity in normal subjects and AD patients. Applied in early AD, it should facilitate inhibitor treatment by confirming central inhibition, optimizing drug dosage, identifying likely responders, and testing surrogate markers of therapeutic response.

Identification and mutation analysis of DOC-1R, a DOC-1 growth suppressor-related gene

The tumor suppressor gene MEN1 and several oncogenes including CCND1/cyclin D1/PRAD1 map to chromosome 11q13. However, molecular and cytogenetic analysis suggests the presence of a second tumor suppressor locus at this chromosome region. We have identified a novel gene from chromosome 11q13, which encodes a protein of 126 amino acids sharing an overall 57% identity with the p12(DOC-1) protein encoded by the DOC-1 gene, the human homolog of hamster putative tumor suppressor doc-1 (deleted in oral cancer-1). We therefore designated the novel gene as DOC-1R for DOC-1-related. The cytogenetic location was confirmed by chromosome fluorescent in situ hybridization. Northern blot analysis indicated that it was expressed in all the tissues examined. DOC-1R protein showed heterogeneous subcellular localization. RT-PCR-SSCP analysis failed to detect deleterious mutations of the DOC-1R transcript in four premalignant oral keratinocyte lines and 20 different cancer cell lines from tumor types which frequently harbor LOH at chromosome 11q13.

Motor correlates of occipital glucose hypometabolism in Parkinson's disease without dementia

OBJECTIVE

To determine whether occipital reduction in regional cerebral glucose metabolism in PD reflects retinal versus nigrostriatal dopaminergic degeneration. We hypothesized that occipital glucose metabolic reduction should be symmetric if parkinsonian retinopathy is responsible for the reduction.

METHODS

PD patients without dementia (n = 29; age 63 +/- 10 years) and normal controls (n = 27; age 60 +/- 12 years) underwent [18F]fluorodeoxyglucose PET imaging. Regional cerebral glucose metabolic rates were assessed quantitatively.

RESULTS

When compared with normal controls, PD patients showed most severe glucose metabolic reduction in the primary visual cortex (mean -15%, p < 0.001). Occipital glucose metabolic reduction was greater in the hemisphere contralateral to the side of the body affected initially or more severely in PD. There was an inverse correlation between side-to-side asymmetries in finger-tapping performance and occipital glucose metabolic reduction (r = -0.45, p < 0.05; n = 28). The correlation was strongest in patients with a relatively early stage of PD with more unilateral motor impairment (Hoehn and Yahr stage I, r = -0.74, p < 0.01; n = 10).

CONCLUSION

The results indicate a pathophysiologic association between nigrostriatal dysfunction and occipital glucose metabolic reduction in PD.

Neuropsychological function and cerebral glucose utilization in isolated memory impairment and Alzheimer's disease

We hypothesized that 20 patients with isolated memory impairment (IMI) would demonstrate [18F]-2-fluoro-2-deoxy-D-glucose utilization and a progression of neuropsychological symptoms consistent with Alzheimer's disease (AD). IMI subjects performed similarly to AD in recall and verbal fluency, but comparable to normal subjects in other areas of cognitive functioning. A positron emission tomography (PET) diagnostic index based on parietal Z-scores categorized IMI patients into normal and abnormal metabolic patterns. Ten of the original 20 IMI patients (50%) reflected PET AD abnormalities. Clinical information was available for IMI patients at three-year follow-up. Ten (50%) had converted to AD, three were found to have pseudodementia and the seven remained IMI. Of the 10 IMI patients with an originally normal PET index, three (30%) were diagnosed with AD at three years. Of the 10 with an abnormal index originally, seven (70%) converted to AD. The finding that memory deficit in IMI was as pronounced as that in AD patients is consistent with the notion that memory is an initial symptom of AD. A substantial number of the IMI patients reflected regional hypometabolism similar to AD, suggesting that IMI is likely an early stage in progressive dementia. A large percentage of IMI patients converted clinically to AD within three years of initial study, though we observed impaired memory functioning well before a clinical diagnosis of AD could be made. In addition to potential clinical utility, IMI and PET represent an opportunity to study dementia in relation to brain chemistry at a time when brain pathology is in the process of development.

Keio Mutation Database for eye disease genes (KMeyeDB)

A database of mutations in human eye disease genes has been constructed. This KMeyeDB employs a database software MutationView which provides graphical data presentation and analysis as a smooth user-interface. Currently, the KMeyeDB contains mutation data of 16 different genes for 18 eye diseases. The KMeyeDB is accessible through http://mutview.dmb.med.keio.ac.jp with advanced internet browsers.

Structural organization and chromosomal localization of the human hepatocyte growth factor activator gene--phylogenetic and functional relationship with blood coagulation factor XII, urokinase, and tissue-type plasminogen activator

The organization and structure of the gene coding for hepatocyte growth factor activator (HGFA) have been determined by isolation of unique clones from a human genomic library. These clones were characterized by restriction mapping, Southern blotting and DNA sequencing. The complete sequence of the gene was determined and found to span about 7.5 kilobases of DNA and consist of 14 exons separated by 13 introns. The coding region of HGFA consists of multiple putative domains that are homologous to those observed in blood coagulation factor XII (FXII). These regions were found as separate exons in the gene, and the exon/intron arrangement was similar to that of FXII, suggesting that the genes for HGFA and FXII have arisen through gene duplication events from a common ancestral gene. The major transcription initiation site is located 75 bp upstream of the translational start codon. The gene was mapped to chromosome 4p16, using spot-blot hybridization on sorted chromosomes and fluorescence in situ hybridization on metaphase chromosome spreads. The phylogenetic and functional relationships between HGFA and FXII as well as urokinase and tissue-type plasminogen activator are discussed.