Lesion-induced differential expression and cell association of Neurocan, Brevican, Versican V1 and V2 in the mouse dorsal root entry zone.

Lack of regeneration in the CNS has been attributed to many causes, including the presence of inhibitory molecules such as chondroitin sulfate proteoglycans (CSPGs). However, little is known about the contribution of CSPGs to regeneration failure in vivo, in particular at the dorsal root entry zone (DREZ), a unique CNS region that blocks regeneration of sensory fibers following dorsal root injury without glial scar formation. The goal of the present study was to evaluate the presence, regulation, and cellular identity of the proteoglycans Brevican, Neurocan, Versican V1 and Versican V2 in the DREZ using CSPG-specific antibodies and nucleic acid probes. Brevican and Versican V2 synthesized before the lesion were still present at high levels in the extracellular matrix of the DREZ several weeks after injury. In addition, Brevican was transiently expressed by reactive oligodendrocytes, and by a subset of astrocytes thereafter. Versican V2 mRNA appeared in NG2-positive cells with the morphology of oligodendrocyte precursor cells. Neurocan and Versican V1 levels were low before injury, and appeared in nestin-positive astrocytes and in NG2-positive cells, respectively, following lesion. Versican V1, but not V2, was also transiently increased in the peripheral dorsal root post-lesion. This is the first thorough description of the expression and cell association of individual proteoglycans following dorsal root lesion. It demonstrates that the proteoglycans Brevican, Neurocan, Versican V1, and Versican V2 are abundant in the DREZ at the time regenerating sensory fibers reach the PNS/CNS border and may therefore participate in growth-inhibition in this region.

Brain derived versican V2 is a potent inhibitor of axonal growth.

In this paper, we identify the chondroitin sulfate proteoglycan versican V2 as a major inhibitor of axonal growth in the extracellular matrix of the mature central nervous system. In immunohistochemical and in situ hybridization experiments we show that this tissue-specific splice variant of versican is predominantly present in myelinated fiber tracts of the brain and in the optic nerve, most likely being expressed by oligodendrocytes. We demonstrate that isolated versican V2 strongly inhibits neurite outgrowth of central and peripheral neurons in stripe-choice assays using laminin-1 as permissive substrate. The inhibitory character of versican V2 is maintained after removal of chondroitin sulfate and N- and O-linked oligosaccharide side chains, but it is abolished after core protein digestion with proteinase-K. Our data support the notion, that intact versican V2 prevents excessive axonal growth during late phases of development and hereby participates in the structural stabilization of the mature central nervous system.

Versican V2 is a major extracellular matrix component of the mature bovine brain.

We have isolated and characterized the proteoglycan isoforms of versican from bovine brain extracts. Our approach included (i) cDNA cloning and sequencing of the entire open reading frame encoding the bovine versican splice variants; (ii) preparation of antibodies against bovine versican using recombinant core protein fragments and synthetic peptides; (iii) isolation of versican isoforms by ammonium sulfate precipitation followed by anion exchange and hyaluronan affinity chromatography; and (iv) characterization by SDS-polyacrylamide gel electrophoresis and Coomassie Blue staining or immunoblotting. Our results demonstrate that versican V2 is, together with brevican, a major component of the mature brain extracellular matrix. Versicans V0 and V1 are only present in relatively small amounts. Versican V2 migrates after chondroitinase ABC digestion with an apparent molecular mass of about 400 kDa, whereas it barely enters a 4-15% polyacrylamide gel without the enzyme treatment. The 400-kDa product is recognized by antibodies against the glycosaminoglycan-alpha domain and against synthetic NH2- and COOH-terminal peptides. Our preparations contain no major proteolytic products of versican, e.g. hyaluronectin or glial hyaluronate-binding protein. Having biochemical quantities of versican V2 available will allow us to test its putative modulatory role in neuronal cell adhesion and axonal growth.

[Molecular pathologic detection of mycobacteria]. / Molekularpathologischer Nachweis von Mykobakterien.

In recent years, significant advances in the diagnosis of mycobacterial infections have been made by the introduction of direct pathogen detection methods. These techniques are usually based on the polymerase chain reaction (PCR) or on a transcription-mediated amplification (TMA) process. The majority of the protocols have been optimized for the detection of mycobacterial nucleic acids in fresh fluid or fresh tissue specimen. Unfortunately pathologists are frequently confronted with the problem that tissues with histologically suspicious lesions have been entirely fixed in formalin. As a result of this routine fixation, DNA and RNA are heavily degraded and the usually high sensitivity of the amplification techniques is greatly impaired. Consequently, only PCR protocols designed for small amplification targets are still suitable for an efficient detection of microbial DNA in formalin-fixed and paraffin-embedded tissues. We therefore adapted PCR assays with amplification products < 200 bp for the detection of M. tuberculosis-complex DNA (targets: IS6110 and 65 kDa-antigen gene) in routine biopsies. Although the sensitivities of the two assays varied significantly with the degree of DNA degradation, we were able to detect M. tuberculosis-complex specific DNA in about 25% of the tissues with a granulomatous inflammation and negative Ziehl-Neelson stain. Recently, we have added a third PCR-assay, which in combination with direct sequencing also allows us to detect DNA from M. leprae and several atypical mycobacteria species. PCR-analysis has significantly improved the diagnosis of mycobacterial infections by supplementing conventional histological examination of formalin-fixed and paraffin-embedded tissues.

Differential expression of versican isoforms in brain tumors.

Versican is a member of the family of large aggregating chondroitin sulfate proteoglycans which are one of the major constituents of brain extracellular matrix (ECM). We examined the expression of versican splice variants at mRNA and protein levels in normal human brain and in gliomas, medulloblastomas, schwannomas, neurofibromas, and meningiomas. RT-PCR revealed transcripts for V0 and V1 in all tissues. V2 mRNA was restricted to gliomas and normal brain, while V3 mRNA was detected in all tissues except for medulloblastomas. Immunohistochemistry using antibodies to the glycosaminoglycan (GAG)-alpha attachment domain of versican (present in V0 and V2) revealed decreased staining of most glioma ECMs compared to normal neuropil, while some abnormal tumor vessels, but not normal cerebral vessels, were GAG-alpha-positive. Expression of the GAG-beta attachment domain (present in V0 and V1) was faint in normal neuropil and cerebral vessels, but increased in tumor vessels and was absent in most glioma ECMs. Both GAG-alpha and GAG-beta were expressed in connective tissue of all nonglial tumors. Our data suggest that V2 is the major versican isoform of normal neuropil and glioma ECM. Furthermore, increased expression in tumor vessels and decreased expression in glioma ECM of the anti-adhesive versican may be related to marked local invasivity and rarity of extracranial metastasis of gliomas.

Clonal disease in extracutaneous compartments in cutaneous T-cell lymphomas. A comparative study between cutaneous T-cell lymphomas and pseudo lymphomas.

Extracutaneous involvement is a sign of poor prognosis in cutaneous T-cell lymphomas (CTCL). Unfortunately it becomes clinically and histologically manifest only late in the course of the disease. It was the purpose of this study to detect clonality in peripheral blood, lymph nodes and bone marrow samples at times when extracutaneous involvement cannot otherwise be demonstrated. In addition to skin biopsies, peripheral blood, lymph node and bone marrow samples from a total of 25 patients were analysed by Southern blotting for clonal gene rearrangement of the T-cell receptor beta-chain. Six of the patients were suffering from mycosis fungoides (MF), four from non-MF CTCL (pleomorphic T-cell lymphomas), seven from Sézary syndrome (SS), eight from pseudolymphoma (insect bites) (PSL), and one from lymphomatoid papulosis (LP). Clonal TcR b gene rearrangements were found in patients with MF in four of five skin probes as well as in two of two lymph node samples and in one of two peripheral blood samples. In SS patients, all skin probes (seven of seven), lymph node samples (six of six), peripheral blood samples (six of six) and one bone marrow specimen had a clonal TcR beta gene rearrangement. In patients with non-MF CTCL, two of four skin, zero of two peripheral blood and one of one bone marrow samples with clonal T cells were detected. All investigated patients showed exactly the same rearrangement pattern at extranodal sites and in the skin, which is proof for the same clone in all compartments. In contrast, no rearrangements were detected in LP and PSL (zero of eight skin probes, zero of two peripheral blood samples). Our results provide strong evidence for an early systemic spread of neoplastic cells in CTCL. However, an initial tumour burden has to be reached in order to lead to a clinically and prognostically relevant manifestation.

Distribution of the large aggregating proteoglycan versican in adult human tissues.

We studied the distribution of the large hyaluronan-binding proteoglycan versican (also known as PG-M) in human adult tissues using affinity-purified polyclonal antibodies that recognize the core protein of the prominent versican splice variants VO and V1. Versican was present in the loose connective tissues of various organs and was often associated with the elastic fiber network. Furthermore, it was localized in most smooth muscle tissues and in fibrous and elastic cartilage. Versican staining was also noted in the central and peripheral nervous system, in the basal layer of the epidermis, and on the luminal surface of some glandular epithelia. In blood vessels, versican was present in all three wall layers of veins and elastic arteries. In muscular arteries the immunoreactivity was normally restricted to the tunica adventitia. However, it appeared in the media and the split elastica interna of atherosclerotically transformed vessel walls. Our survey of the distribution of versican in normal human tissues now forms the basis for extended studies of potentially aberrant versican expression during pathogenic processes.

Primary cutaneous T-cell-rich B-cell lymphoma. A case report with a 13-year follow-up.

Cutaneous B-cell lymphomas constitute approximately 20% of primary cutaneous lymphomas. Most histologic subtypes of nodal B-cell lymphomas also occur primarily in the skin. The recently described T-cell-rich B-cell lymphomas (TCRBCLs) manifest mainly in the lymph nodes. This article presents a case of TCRBCL arising primarily in the skin, the origin of which could be traced back 13 years. The patient is a 59-year-old man. Plaque-like and nodular skin infiltrates had first appeared in the left preauricular region. Repeated examinations never found any extracutaneous involvement. A skin biopsy and a retrospectively studied 10-year-old skin specimen showed identical histologic features. Immunohistochemistry identified the TCRBCL previously considered as cutaneous Hodgkin's disease or a diffuse centroblastic centrocytic non-Hodgkin's lymphoma. A clonal B-cell population was detected by polymerase chain reaction, showing a rearrangement of IgH gene. The case of this patient shows that primary cutaneous TCRBCLs, similarly to other B-cell lymphomas in the skin, may have a good prognosis, in contrast to their nodal counterparts.

Immunohistochemical and mutation analyses demonstrate that procollagen VII is processed to collagen VII through removal of the NC-2 domain.

Collagen VII is the major structural constituent of anchoring fibrils in the skin. It is synthesized as a procollagen that is larger than the collagen deposited in the tissue. In this study, we investigated the conversion of procollagen VII to collagen VII in human skin and in cutaneous cells in vitro and identified the propeptide using domain-specific antibodies. For this purpose, two bacterial fusion proteins containing unique sequences of the carboxy-terminal globular NC-2 domain of procollagen VII were prepared, and polyclonal antibodies raised against them. Immunoblotting showed that the anti-NC2 antibodies reacted with procollagen VII isolated from cultured keratinocytes, but not with collagen VII extracted from the skin. Immunohistochemical experiments with the NC-2 antibodies revealed a strong reaction in cultured keratinocytes, but the basement membrane zone of normal skin remained negative. The staining could not be rendered positive by chemical or enzymatic unmasking of potential hidden epitopes in the skin, indicating that most of the NC-2 domain is absent from normal skin. In contrast, a positive staining with NC-2 antibodies was observed in the skin of a patient with NC-2 antibodies was observed in the skin of a patient with dystrophic epidermolysis bullosa, who carried a 14-bp deletion at one of the intro-exon junctions of the collagen VII gene. This aberration led to an in-frame skipping of exon 115 from the mRNA and eliminated 29 amino acids from the NC-2 domain which include the putative cleavage site for the physiological processing enzyme, procollagen C-proteinase. The results indicate that in normal human skin, the removal of the NC-2 domain from procollagen VII precedes its deposition at the dermal-epidermal junction. Furthermore, they suggest that an aberration in the procollagen VII cleavage interferes with the normal fibrillogenesis of the anchoring fibrils.

Lymphomatoid papulosis--treatment with recombinant interferon alfa-2a and etretinate.

Lymphomatoid papulosis is a rare cutaneous lymphoproliferative disorder with nodular, papulonecrotic or plaque-like lesions. Although it is clinically benign, the histology shows large, atypical lymphoid cells that display antigenic markers of activated T-helper lymphocytes and express CD30. There is a close relationship to Hodgkin's disease and to Ki-1-positive anaplastic large-cell lymphoma of the skin. For therapy, various modalities such as PUVA, steroids and acyclovir have been used. We report on a patient with a 10-year history of disease. Treatment with interferon alfa-2a, 3 MU 3 times/week for 4 weeks, and etretinate, 50 mg/day for 5 months, was initially successful, but lesions further relapsed 5 months after cessation of the therapy.

Occult hepatosplenic T-gamma delta lymphoma. Value of genotypic analysis in the differential diagnosis.

We report on a patient with a rare hepatosplenic gamma delta T-cell lymphoma (gamma delta TCL) presenting clinically with B-symptoms, hepatosplenomegaly and pancytopenia. During the initial stage of the disease the sparse malignant cells could not be detected histologically. Furthermore, their identification was obscured by massive macrophage proliferation with haemophagocytosis in the spleen. Diagnosis was established by detection of a clonal T-cell receptor (TcR) rearrangement and, retrospectively, by demonstration of rare cells expressing and aberrant T-cell phenotype. The findings in this patient emphasize that minimal neoplastic T-cell infiltrates can lead to severe clinical symptoms. Initial biopsy findings may be misinterpreted as benign. Gamma delta TCL may elaborate lymphokines that suppress haematopoiesis, leading to pancytopenia and macrophage proliferation.

A novel glycosaminoglycan attachment domain identified in two alternative splice variants of human versican.

We have cloned an alternatively spliced glycosaminoglycan attachment domain (GAG-alpha) of human versican from cDNA libraries derived from U251MG glioma cells. Inserted carboxyl-terminal of the hyaluronan-binding region, this domain adds another 987 amino acids to the original versican (V1) core protein giving rise to the large V0 isoform with 3396 amino acids and 17-23 putative glycosaminoglycan attachment sites. The GAG-alpha domain is encoded by exon 7 of the human versican gene (Naso et al., J. Biol. Chem., 32999-33008). Sequence comparisons revealed a slight similarity to the alternative splice domain of PG-M, further supporting the notion that PG-M is the chicken homologue of versican. On immunoblots of a proteoglycan preparation from U251MG culture medium, anti-GAG-alpha antibodies reacted exclusively with the larger of two versican core proteins recognized by antibodies against the original GAG-beta domain. Using reverse transcription-polymerase chain reaction, we detected both the V0 and V1 isoforms in the cerebral cortex, aorta, intervertebral disc, liver, myometrium, and prostate, whereas keratinocytes exclusively expressed versican V1. In brain tissue, we identified a short versican variant (V2) including only the GAG-alpha domain. By expressing particular splice forms of versican, cells may control the hydration properties of their pericellular hyaluronan coat and thus could modulate interactions with the extracellular matrix or neighboring cells.

Versican is expressed in the proliferating zone in the epidermis and in association with the elastic network of the dermis.

The expression of the large chondroitin sulfate proteoglycan versican was studied in human adult skin. For this purpose, bacterial fusion proteins containing unique portions of the versican core protein were prepared. Polyclonal antibodies against the fusion proteins specifically reacted with versican from a proteoglycan fraction of MG63 osteosarcoma cells. In immunohistochemical experiments, the affinity-purified antibodies localized versican in the stratum basale of the epidermis, as well as in the papillary and reticular layers of the dermis. An apparent codistribution of versican with the various fiber forms of the elastic network of the dermis suggested an association of versican with microfibrils. Both dermal fibroblasts and keratinocytes expressed versican in culture during active cell proliferation. In line with the observation that versican is absent in the suprabasal layers of the epidermis where keratinocytes terminally differentiate, culture conditions promoting keratinocyte differentiation induced a down-regulation of versican synthesis. In Northern blots versican mRNA could be detected in extracts from proliferating keratinocytes and dermal fibroblasts. Comparison of RNA preparations from semi-confluent and confluent fibroblast cultures demonstrated decreasing amounts of versican mRNA at higher cell densities. This inverse correlation of versican expression and cell density was confirmed by indirect immunofluorescence staining of cultured fibroblasts and keratinocytes. The localization of versican in the basal zone of the epidermis as well as the density dependence of versican in cell cultures suggest a general function of versican in cell proliferation processes that may not solely be confined to the skin.

[Expression of the extracellular matrix proteoglycan, versican, in human skin]. / Expression des extrazellulären Matrix-Proteoglykans Versican in humaner Haut.

Extracellular matrix chondroitin/dermatan sulfate proteoglycans are present in a wide variety of tissues including cartilage, placenta, aorta, tendon, brain and skin. They possibly participate in cellular processes such as cell adhesion, migration and proliferation. Recently, we have determined the entire primary structure of the large fibroblast proteoglycan, versican, on the basis of its cDNA sequence. Versican belongs to the family of large aggregating proteoglycans. Other members of the family, which have been characterized in terms of their primary structure, are aggrecan in cartilage and neurocan isolated from brain tissues. Due to the extensive sequence similarities between these three proteoglycans in the N- and C-terminal domains and due to the high degree of carbohydrate substitution, the generation of antibodies monospecific for versican has been difficult. To avoid cross-reactivity with aggrecan and neurocan, we therefore prepared unique portions of versican in a bacterial expression system and used them to immunize rabbits (Zimmermann et al., 1994). The affinity-purified anti-fusion protein antibodies specifically reacted with intact versican from an osteosarcoma cell line. First immunohistochemical experiments on cryo-sections of human skin revealed anti-versican staining in the stratum basale of the epidermis, as well as in the papillary and reticular layers of the dermis. By indirect immunofluorescence, Northern and Western blotting we could demonstrate that both, dermal fibroblasts and keratinocytes express versican in primary cultures. A striking inverse correlation between versican expression and cell density was observed. Analogous to the in vivo situation, keratinocytes induced to terminally differentiate ceased to express versican.(ABSTRACT TRUNCATED AT 250 WORDS)

T-cadherin 2: molecular characterization, function in cell adhesion, and coexpression with T-cadherin and N-cadherin.

Cadherins are integral membrane glycoproteins that mediate calcium-dependent, homophilic cell-cell adhesion and are implicated in controlling tissue morphogenesis. T-cadherin is anchored to the membrane through a glycosyl phosphatidylinositol (Ranscht B, Dours-Zimmermann MT: Neuron 7:391-402, 1991) and expressed in a restricted pattern in developing embryos (Ranscht B, Bronner-Fraser M: Development 111:15-22, 1991). We report here the molecular and functional characterization of the T-cadherin isoform, T-cadherin 2 (Tcad-2) and the expression of the corresponding mRNA. Tcad-2 cDNA differs in its 3' nucleotide sequence from T-cadherin cDNA and encodes a protein in which the carboxy terminal Leu of T-cadherin is substituted by Lys and extended by the amino acids SerPheProTyrVal. By RNase protection, mRNAs encoding the T-cadherin isoforms are coexpressed in heart, muscle, liver, skin, somites, and in neural tissue. Many tissues contain both T-cadherin and Tcad-2 mRNAs in conjunction with N-cadherin transcripts, and T-cadherins and N-cadherin proteins are coexpressed on the surface of individual neurons in vitro. Expression in Chinese hamster ovary cells (CHO) revealed that Tcad-2 is a glycosyl phosphatidylinositol-anchored membrane protein that functions in calcium-dependent, homophilic cell adhesion. The identification of a functional T-cadherin isoform and the coexpression of T-cadherins and N-cadherin by individual cells suggest that specific adhesive interactions of embryonic cells may involve a complex interplay between multiple cadherins.

T-cadherin, a novel cadherin cell adhesion molecule in the nervous system lacks the conserved cytoplasmic region.

We have characterized T-cadherin, a glycoprotein of 95 kd from chick embryo brain by expression cloning and sequencing of corresponding cDNAs. The nucleotide sequence predicts a novel cadherin cell adhesion molecule in the nervous system. Surprisingly, the isolated cDNAs do not encode the cytoplasmic region conserved in other cadherin subclasses. Biochemical analysis revealed that this truncated (T) cadherin is attached to the neuronal plasma membrane through a glycosyl phosphatidylinositol anchor. T-cadherin is a component of different neuronal populations and is expressed in a temporally and spatially restricted pattern during axon growth. These results are consistent with a putative role of T-cadherin in axon growth and guidance.