The structural organization of the gene for the human cysteine-proteinase inhibitor cystatin C was studied. Restriction-endonuclease digests of human genomic DNA hybridized with human cystatin C cDNA and genomic probes produced patterns consistent with a single cystatin C gene and, also, the presence of six closely related sequences in the human genome. A 30 kb restriction map covering the genomic region of the cystatin C gene was constructed. The positions of three polymorphic restriction sites, found at examination of digests of genomic DNA from 79 subjects, were localized in the flanking regions of the gene. The gene was cloned and the nucleotide sequence of a 7.3 kb genomic segment was determined, containing the three exons of the cystatin C structural gene as well as 1.0 kb of 5'-flanking and 2.0 kb of 3'-flanking sequences. Northern-blot experiments revealed that the cystatin C gene is expressed in every human tissue examined, including kidney, liver, pancreas, intestine, stomach, antrum, lung and placenta. The highest cystatin C expression was seen in seminal vesicles. The apparently non-tissue-specific expression of this cysteine-proteinase inhibitor gene is discussed with respect to the structure of its 5'-flanking region, which shares several features with those of housekeeping genes.

A -trace variant protein is the major constituent of the amyloid fibrils in patients from Iceland with hereditary cerebral hemorrhage with amyloidosis. The protein consists of 110 residues and is similar to human urinary V-trace basic protein (or cystatin C) beginning at its 11th aminoterminal residue. It has an amino acid substitution (glutamine for leucine) at position 58 (position 68 in v-trace numbering), which is near the proposed active site of related proteinsnamely, cysteine protease inhibitors and kininogens. It is postulated that a point mutation has occurred, leading to the production of an unusual protein that is abnormally degraded, bound, and/or precipitated. Alternatively, Vtrace basic protein may be genetically polymorphic, and the variant described here may represent an as-yet-undiscovered isotype or an allelic form that is linked to, but not responsible for, the deposition disease. Our data on the structure of a V-trace variant protein suggests that its gene expresses a polyprotein precursor in which active peptides are flanked by basic amino acid residues that permit cleavage to liberate small internal peptides. It is likely that the nucleotide sequence coding for Arg-Xaa and Lys-Xaa repeated several times in the molecule may function as alternative splicing sites for mRNA processing.Amyloidosis comprises a heterogeneous group of disorders of different etiology characterized by the relentless deposition (mainly extracellular) of a number of fibrillar proteins, which may be distinguished from each other immunohistologically and biochemically. Amyloid fibrils are composed of low molecular weight subunits that originate by polymerization and/or proteolysis of serum proteins. These subunit proteins have a predominant 3-pleated-sheet configuration, as shown by spectroscopic studies and x-ray diffraction (1).Hereditary cerebral hemorrhage with amyloidosis (HCH-WA) is an autosomal dominant form of amyloidosis that is restricted to the cerebral vasculature and leads to hemorrhagic and thrombotic strokes causing death before the age of 40 yr; 128 affected family members within eight families originating from one geographical area in Iceland have been identified (refs. 2 and 3; unpublished studies). Recently a similar autosomal dominant cerebral amyloid angiopathy has been described in The Netherlands (4). The histopathology of HCHWA brains is similar to that of the congophilic angiopathy associated with some cases of Alzheimer disease and cases of cerebral hemorrhage caused by sporadic congophilic angiopathy. In HCHWA there are no plaques or neurofibrillary tangles, and the amount of vascular amyloid is quantitatively much greater than in the two other forms of cerebral amyloid angiopathy (5, 6), making chemical extraction of the amyloid fibrils feasible. We have reported (7) the amino-terminal sequence of the amyloid fibrils obtained from the brain of patients dying of HCHWA. This paper presents the complete primary sequence and discusses its relationship to related proteins and its potential ...

In both the beta-protein and cystatin C amyloid angiopathies, cerebrovascular amyloid deposition was associated with an increase or activation of monocyte/macrophage lineage cells. Prominent reactions of monocyte/macrophage lineage cells admixed with CD4+ and CD8+ T cells (granulomatous angiitis) were occasionally associated with beta-protein angiopathy. In some of these cases, the absence of amyloid P component might be related to pathogenesis of the granulomatous reaction.

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