[Pharmacological treatment for patients with borderline personality disorder: practice and study results]

Many patients with borderline personality disorder (BPD) receive pharmacological treatment. On account of the few treatment guidelines and the often changing symptoms, different substances are used. The present article summarises treatment-practice and study results concerning the pharmacological treatment of BPD.

The Deceleration Capacity - a New Measure of Heart Rate Variability Evaluated in Patients With Schizophrenia and Antipsychotic Treatment

Background

Schizophrenia is associated with increased cardiac mortality. A disturbed autonomic modulation of heart rate (HR) has been described in patients with schizophrenia in whom antipsychotic medication may represent an additional cardiac risk. The novel measure deceleration capacity (DC) of heart rate predicts cardiac mortality in patients with cardiovascular illnesses. The aim of the present paper was to calculate DC in patients with schizophrenia and to compare this measure with established parameters of heart rate variability (HRV).

Methods

HRV and DC were calculated in 24-hour electrocardiogram (ECG) recordings of 20 unmedicated, 40 medicated patients with schizophrenia and 40 controls. As activity has a major influence on HRV, 4-hour periods of “sleep-” and “wake-” ECG were evaluated as additional parameters. Actigraphy was used to ensure comparable levels of activity in patients and controls.

Results

The DC as well as the other established HRV measures were not significantly different comparing unmedicated patients with schizophrenia to healthy controls. However, medicated patients showed a significant reduction of DC calculated from ECG recordings during 4 hour over night periods.

Conclusion

Calculation of DC might contribute to a better monitoring and identification of an increased risk of cardiac mortality in patients with schizophrenia undergoing antipsychotic treatment.

[Delusional misidentifications. Symptoms and neuropsychological models]

Delusional misidentifications include the Capgras delusion, Fregoli delusion, the delusion of subjective doubles and other less frequent symptoms. A common denominator of these unspecific psychopathological symptoms is the patients' denial of their identity or the convinction that their identity or the identity of relatives has been altered. These delusional symptoms occur in the context of somatic and mental diseases, most frequently in schizophrenia and dementia. According to neuropsychological and neuroanatomical studies delusional misidentifications are facilitated by lesions of the temporo-limbic system leading to an impairment in the affective recognition and reality control. Patients suffering from delusional misidentifications have a higher risk of aggressive behaviour which emphasises their clinical relevance.

[Brain stem and cerebellar atrophy in neurosyphilis]

A 54-year-old man suffered from serologically proven neurosyphilis with tetraspastic syndrome and bladder dysfunction. He showed a pronounced psychopathy with cognitive decline and attention/concentration deficits. MRI showed slowly progressive cerebellar and brainstem atrophy, which has rarely been described over the past decades. During times of higher incidence and prevalence of neurosyphilis, infratentorial atrophy had been described occasionally, but today this clinical manifestation has been all but forgotten.

[Patient satisfaction with psychiatric care. Historical perspective, methods and results from the international literature]

Whereas evaluations of patients' satisfaction have been made in the U.S. beginning in the early 50's, there has been an increasing interest in German-language countries only in recent years. The present article summarizes the aims, methods and results of patient satisfaction surveys. A selection of questionnaires comprising the Client Satisfaction Questionnaire (CSQ, 43), the General Satisfaction Questionnaire (GSQ, 37) and the Verona Service Satisfaction Scale (VSSS, 72) is described in detail. The vast majority of the published studies suggest a high rate of general satisfaction with psychiatric inpatient services, whereas most of the more specific findings remain less well demonstrated. The main problem involved with this type of survey seems to be the term "patient satisfaction", which is defined as the relation between the patient's expectations in regard to psychiatric services and the perception of the service the patient has received. This means that the level of patient satisfaction itself does not allow a conclusion to be drawn on the objective quality of a psychiatric treatment. Nevertheless the authors are convinced of the importance of patient satisfaction questionnaires when these questionnaires are part of a quality assurance program.

[Homicide and hebephrenia-like syndrome in metachromatic leukodystrophy]

We report a patient with metachromatic leukodystrophy (MLD) with a first manifestation of homicide. On admission the patient showed a hebephrenia-like syndrome with inappropriate affect, thought disorder and behavioral changes. Magnetic resonance tomography (MRT) findings suggested a diagnosis of MLD, which was confirmed by a decreased activity of leucocyte arylsulfatase A and an excessive urinary sulfatide excretion.

Cell fate specification in an in vitro model of neural development

We have studied in an in vitro model of neural development the effect of neighboring cells on the fate of single fluorescently labeled precursor cells. In one line of experiments, PCC7-Mz1 embryonal carcinoma cells were transiently transfected with "green fluorescent protein" (GFP) and, following incubation with 0.1 microM all-trans retinoic acid (RA), the number and morphology of derivatives (neuronal or non-neuronal) was determined that form groups of GFP-expressing cells in a surrounding of unlabeled cells. Because single PCC7-Mz1 cells can produce single-lineage and mixed-lineage derivatives, they are individually pluripotent. In another line of experiments, we have analyzed the fate of GFP-expressing PCC7-MzN cells in different cellular environments. Whereas in the absence of other cells, PCC7-MzN cells exclusively differentiated to neuronal derivatives following RA induction (Lang, E., M. L. Mazauric-Stüker, A. Maelicke, J. Cell Biol. 109, 2481-2493 (1989)), they differentiated also to non-neuronal phenotypes (astrocytes and fibroblasts) when co-cultured with either PCC7-Mz1 stem cells or freshly RA-induced cells. The fate of PCC7-MzN cells could also be shifted in the absence of other cells when the cells were grown on laminin-coated surfaces. These results suggest that a putative fate-shifting activity (FSA) is released by PCC7-Mz1 and PCC7-MzN cells which requires, at least in the case of MzN cells, presentation by extracellular matrix-like structures in order to function in cell fate specification. Very few other cell types, in particular primary cultures of mouse forebrain cells of embryonic day 13, were capable of shifting the developmental potential of PCC7-MzN cells in a similar manner as PCC7-Mz1 cells do. We conclude that cell type specification in this model of neural development may occur by similar mechanisms as have been established in Drosophila neurogenesis. A default pathway (neuronal) is modulated by lateral signaling between neighboring cells so that cellular diversity can arise from initially homogeneous populations of progenitor cells.

Cloning of the human NCNF gene

We have cloned from a cDNA library of human testis tissue the human homologue to the mouse nuclear orphan receptor NCNF (neuronal cell nuclear factor). The open reading frame encodes a protein of 480 amino acids, the sequence of which (EMBL accession no. X99975) is 98.3% identical to the mouse homologue. Northern blot analysis of adult human tissues revealed a broad pattern of tissue expression. Similar to NCNF expression in mouse testis, two transcript forms of the single copy gene are expressed in human tissues. The two transcript forms which differ only in their 3'UTR, result in human from differential polyadenylation, in mouse from alternative splicing. Based on the high level of sequence identity of human and murine NCNF, it is likely that also the human nuclear receptor is involved in the control of neurogenesis and gametogenesis.

De novo acquisition of neuronal polarity in retinoic acid-induced embryonal carcinoma cells

The mouse embryonal carcinoma cell line PCC7-Mz1 represents an advantageous model to study acquisition of polarity by neurons. During the first two days after differentiation is induced by the addition of retinoic acid, the neuronal derivatives develop extensions which for at least four more days do not differ from each other in growth characteristics, morphology, and marker expression. Beginning around differentiation day 6 and following the relocation of the nucleus from a central to a polar position in the cell soma, the morphology and marker expression changes dramatically: expression of MAP2 diminishes and eventually disappears in the thinner neurite (future axon), which originates at the nucleated pole, but remains strong in the branched, broad based neurite(s). The opposite changes in expression are observed for synaptophysin, together with a clustering of the vesicle protein in varicosity-like areas. Complete segregation of expression of the two markers is achieved around day 12, shortly followed by dendrite-specific location of MAP2 mRNA and the ability to generate and conduct action potentials. Our studies add several aspects to the process of neuronal polarity acquisition, as it was previously studied in primary cultures of embryonic neurons: (i) we monitored neuronal differentiation from the birth of neurons, rather than from later and less defined maturation stages, (ii) cell nucleus relocation may be associated with the induction of neuronal polarity, and (iii) functional competence of neurons is closely associated with previous acquisition of polarity. Acquisition of polarity by PCC7-Mz1 neuronal derivatives probably refers to de novo acquisition rather than to reestablishment of polarity.

Neuronal cell nuclear factor--a nuclear receptor possibly involved in the control of neurogenesis and neuronal differentiation

We have cloned from a cDNA library of neuronal derivatives of retinoic-acid-induced embryonic carcinoma cells a nuclear receptor that may be involved in the control of late neurogenesis and early neuronal differentiation. The receptor which is practically identical in sequence with germ cell nuclear factor, has been designated neuronal cell nuclear factor (NCNF). NCNF is exclusively expressed in the neuronal derivatives of PCC7-Mz1 cells, with the expression beginning within hours of exposure to retinoic acid. In the developing mouse brain, NCNF is expressed in the marginal zones of the neuroepithelium which are known to contain young postmitotic neurons. NCNF binds to the DR0 sequence thereby silencing transcription. Because NCNF does not recognize hormone response elements of other nuclear receptors tested and does not heterodimerize with these, it probably binds exclusively as a homodimer. NCNF may induce neuronal differentiation by repressing the activity of genes that permit cell fates other than the neuronal one.

Cloning of several genes coding for retinoic acid nuclear receptors in the mouse embryonal carcinoma cell line PCC7-MZ1

Mouse embryonal carcinoma cell line PCC7-Mz1 can be induced by retinoic acid (RA) to differentiate into several well defined phenotypes of neuroectodermal origin (Lang, E. et al. (1989) J. Cell. Biol. 109, 2481-2493). Several subclones of the cell line (clonal variants) differ from each other in their developmental potential. To test whether these differences in cellular fate are due to somatic mutations in specific genes of these cells, we have cloned full length cDNAs coding for the alpha 1 and beta 2 isoforms, and partial length cDNAs coding for the alpha 2, beta 1 and beta 3 isoforms of the retinoic acid nuclear receptor (RAR). The cloned cDNAs did not differ in sequence from those of normal mouse cells. Using as probe the beta 2-RAR promoter region from mouse liver, we also checked for restriction fragment length polymorphism in the promoter regions of RA-inducible and RA-resistant cell variants. No alterations in this region of RAR genes was found in the clonal variants tested. The different patterns of derivatives produced by the variants upon exposure to RA therefore cannot be caused by somatic mutations in RAR genes of the tumor cell lines.

Expression of retinoic acid nuclear receptors in the mouse embryonal carcinoma cell line PCC7-Mz1

Mouse embryonal carcinoma cell line PCC7-Mz1 can serve as a model of mammalian neural development [1989, J. Cell. Biol. 109, 2481-2493]. Upon exposure to all-trans retinoic acid (RA), Mz1 cells differentiate into a stable pattern of neurons, astroglia and fibroblasts whereas variants of the parental cell line either are restricted in their patterns of derivatives or do not respond at all to RA. Using gene probes specific for the alpha 1, alpha 2 and beta 2 isoforms of the retinoic acid nuclear receptor, we have studied by Northern blot analysis the expression of these transcription factors in uninduced and induced cells of clone Mz1 and in variants with different developmental potential. alpha 1-RAR is expressed constitutively in all variants independent of whether RA is present or not. Soon after addition of 10(-7) M RA, alpha 2-RAR is induced in RA-responsive cells reaching within a few hours a plateau level that remains unchanged throughout the developmental process. In contrast, the beta 2 isoform is expressed only transiently after RA-induction despite the continuous presence of RA. Other RAR isoforms are expressed only in trace amounts.

Cloning and functional expression of Dfurin2, a subtilisin-like proprotein processing enzyme of Drosophila melanogaster with multiple repeats of a cysteine motif

Production of a variety of regulatory eukaryotic proteins, such as growth factors and polypeptide hormones, often involves endoproteolytic processing of proproteins at cleavage sites consisting of paired basic residues. The first known mammalian proprotein processing enzyme with such specificity is the human fur gene product furin. Structurally and functionally, furin is related to the subtilisin-like serine endoprotease kexin (EC 3.4.21.61) of yeast Saccharomyces cerevisiae; unlike kexin, it contains a cysteine-rich region with an unknown function. Here, we describe cloning and sequencing of a 5.8-kbp cDNA of the Dfur2 gene, a fur-like gene of Drosophila melanogaster, which we found expressed during various stages of development. This Dfur2 cDNA has an open reading frame for a 1680-residue protein, called Dfurin2. Dfurin2 contains similar protein domains as mammalian furin, however, it has an extended amino-terminal region and its cysteine-rich region is much larger than that of mammalian furin. Because of this latter phenomenon, we were able to identify a particular cysteine motif that was repeated multiple times in Dfurin2 but present only twice in mammalian furin. Furthermore, we show that Dfur2 encodes an endoproteolytic enzyme with specificity for paired basic amino acid residues as, in cotransfection experiments, correct cleavage was demonstrated of the precursor of the von Willebrand factor but not of a cleavage mutant. Finally, Dfur2 was mapped to region 14C of the X chromosome of D. melanogaster.

Parvoviruses are inefficient in inducing interferon-beta, tumor necrosis factor-alpha, or interleukin-6 in mammalian cells

To investigate a possible role of cytokines in parvovirus-mediated suppression of tumorigenesis, we tested in cell culture whether parvoviruses are able to induce interferon (IFN)-beta, tumor necrosis factor (TNF)-alpha or interleukin-6 (IL-6). Infection of rodent or human cells with the parvoviruses minute virus of mice (MVM), H-1 or adeno-associated virus (AAV) types 2 or 5 failed to induce expression of the luciferase or beta-galactosidase reporter genes transfected into these cells as constructs containing an IFN-beta promoter. Parvoviruses did weakly induce synthesis of TNF-alpha and of IL-6 in cell culture and could slightly enhance synthesis of these cytokines when induced by other agents. These in vitro data suggest that the rather unspecific tumor-suppressive properties of parvoviruses are unlikely to be attributable to stimulation of the synthesis of IFN, TNF or IL-6.

Tissue-specific expression of murine keratin K13 in internal stratified squamous epithelia and its aberrant expression during two-stage mouse skin carcinogenesis is associated with the methylation state of a distinct CpG site in the remote 5'-flanking region of the gene

Under normal conditions, the expression of the murine type-I keratin K13 is restricted to the suprabasal, differentiating cell layers of internal stratified squamous epithelia that line the oral cavity and the upper digestive tract. It is, however, also expressed aberrantly but constitutively in only the differentiating parts of 7,12-dimethylbenz[alpha]anthracene/12.0-tetradecanoyl-phorbol-13-acetate (DMBA/TPA) induced malignant epidermal tumors of the back skin of mice, whereas its likewise suprabasal expression in papillomas is highly variable [27]. In an approach to unravel regulatory DNA sequence elements involved in the tissue-specific and aberrant K13 expression, the 5'-flanking region of the gene was analyzed with regard to potential methylation sites and DNase hypersensitive regions. We report on the identification of a CpG dinucleotide (designated M1; located about 2.3 kb upstream of the transcriptional start site), whose methylation state correlates with the differential gene activity in various epithelia and tumors. We show that in K13-nonexpressing integumental epidermis the M1 site is methylated in both suprabasal and basal cells. In contrast, internal stratified squamous epithelia (i.e. tongue, esophagus, forestomach) exhibit an unmethylated M1 site not only in their suprabasal. K13-expressing cells, but also in basal cells--in which, however, the keratin is not yet synthesized. The identical situation is encountered in DMBA TPA-induced moderately differentiating epidermal squamous cell carcinomas with compartmentalized K13 expression. In papillomas we observed a striking correlation between the extent of both suprabasally expressed K13 protein and demonstrable DNA copies carrying an unmethylated M1 site. Moreover we found that the sequence region around the M1 site was DNAseI hypersensitive in K13-expressing malignant tumors, but DNaseI insensitive in K13-nonexpressing epithelia and cells. DNAseI hypersensitivity in K13-expressing tissues was, however, independent of an active transcription of the gene in differentiating cells or transcriptional inertia in basal cells. These results strongly suggest that the sequence element around the demethylated M1 site is involved in a multi-level control mechanism mediating the selective expression of the K13 gene in internal squamous epithelia and in DMBA/TPA-induced epidermal tumors.

Isolation and functional characterization of the murine interferon-beta 1 promoter

A murine cosmid clone harboring the single-copy interferon-beta 1 (IFN-beta 1) gene and extended flanking sequences was isolated. The functional IFN-beta 1 promoter is contained within a 170-bp DNA fragment located 5' of the coding sequence. This was shown by fusion of this fragment to a heterologous reporter gene and transient as well as stable expression in mouse L and monkey CV-1 cells. With the help of these functional assays, it could be demonstrated that the 5'-flanking sequences are the target for the typical regulatory action of common type I IFN activators. DNA sequencing reveals a considerable homology to the human IFN-beta 1 promoter within the 280 upstream base pairs. The homology is particularly pronounced within the DNA region containing the virus responsive element (VRE). This phenomenon may explain the similarity of both genes in the mode of regulation. The mouse promoter fragment compared with the human equivalent was shown to be several times more efficient in transcriptional activation in murine and primate cells.

The intermediate filament system of the keratinizing mouse forestomach epithelium: coexpression of keratins of internal squamous epithelia and of epidermal keratins in differentiating cells

The internal epithelium of mouse forestomach represents a fully keratinized tissue that has many morphological aspects in common with the integumental epidermis. In the present study we have, therefore, analyzed keratin expression in the total epithelium, in subfractions of basal cells and in living and dead suprabasal cells that were obtained by Percoll density gradient centrifugation of trypsin-dissociated forestomach keratinocytes. The keratin analysis revealed that basal forestomach keratinocytes synthesize the same keratin types as basal epidermal cells (60000, 52,000 and 47,000 daltons), whereas differentiating cells contain both the epidermal suprabasal keratin pair (67,000 and 59,000 daltons) and the suprabasal keratin pair characteristic for other internal squamous epithelia (57,000 and 47,000 daltons). Indirect immunofluorescence using an antibody recognizing the members of the epidermal-type suprabasal keratin pair and in-situ-hybridization experiments using specific cDNA probes for the members of the internal-type keratin pair showed that the two keratin pairs are uniformly coexpressed in living suprabasal forestomach keratinocytes. Furthermore, it could be shown that distinct cells in the basal cell layer acquire the ability to express both the 67,000/59,000 dalton and the 57,000/47,000 dalton keratin pair and that some basal cells apparently lose the ability to synthesize mRNAs for basal keratins.

Aberrant expression during two-stage mouse skin carcinogenesis of a type I 47-kDa keratin, K13, normally associated with terminal differentiation of internal stratified epithelia

Specific keratin cDNA probes and monospecific antikeratin antisera were used to analyze mouse epidermis and epidermal tumors for the expression of a type I 47-kDa keratin, K13, normally associated with terminal differentiation of internal stratified epithelia. We demonstrated that this keratin was virtually absent from the entire body epidermis at various stages of development. Also, it was not detected in various forms of acute and chronic epidermal hyperproliferation or in epidermal cells cultured under conditions that favored either cell proliferation or in vitro differentiation. In contrast, K13 was consistently expressed in squamous cell carcinomas of the skin induced by 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate (TPA), whereas papillomas obtained by the same two-stage protocol were distinctly heterogeneous with regard to the expression of this keratin. These findings were true for two different strains of mice (NMRI and Sencar). Papillomas collected from Sencar mice after 12 wk or from NMRI mice after 15 wk of promotion with TPA were either negative for K13 or elicited variable amounts of this keratin. In all cases of positive expression of K13 in tumors, as in normal stratified internal epithelia, both the keratin protein and its mRNA invariably occurred in the differentiating cell compartments. In contrast to what we found in internal stratified epithelia, however, K13 was expressed without its commonly encountered type II 57-kDa partner, K4. Papillomas negative for the K13 protein were also devoid of K13 transcripts. This indicates that the aberrant K13 expression in tumors is regulated at the level of transcription. Our results suggest that K13 may provide a marker for malignant conversion in the mouse two-stage skin carcinogenesis model and may be especially suited for studies of gene expression regulation.

An unusual type-II 70-kilodalton keratin protein of mouse epidermis exhibiting postnatal body-site specificity and sensitivity to hyperproliferation

Keratin extracts from the epidermis of adult mouse ears, footpads, and tail contain large amounts of a 70-kilodalton (kDa) protein which has not been detected in any other body site of the adult mouse or in the epidermis of neonatal mice. Two-dimensional immunoblotting using an antiserum which recognizes both type-I and type-II murine keratins revealed that the 70-kDa protein is indeed a keratin belonging to the type-II subfamily. Its postnatal induction occurs during the first 2 weeks after birth, being first observed in tail epidermis, then in footpad epidermis, and only rather late in ear epidermis. Although in vitro translation experiments with polyA+-RNA from adult tail and footpad epidermis consistently failed to reveal the 70-kDa protein among the translation products, we obtained evidence using a specific cDNA clone that, in vivo, the protein is encoded by a discrete mRNA. This clone, termed pke70, was isolated from a cDNA library of footpad epidermal mRNA. Homology comparisons with a variety of known keratin cDNAs indicated that pke70 contains sequence information for a type-II keratin that is substantially larger than the mouse 67-kDa keratin protein. Northern-blot analysis with a specific 3'-fragment of pke70 demonstrated a single 2.8 +/- 0.1 kb mRNA species exclusively in adult ear, footpad, and tail epidermis. In situ hybridization with the same fragment revealed the presence of the pke70-hybridizing mRNA in both basal and suprabasal cells of ear and footpad epidermis as well as in the orthokeratinizing parts of the tail epidermis; however in the epidermis covering the balls of the feet, labeling was restricted to suprabasal cells at the base of these nodular elevations. Continuous treatment of adult tail or ear epidermis with hyperplasiogenic agents, e.g., vitamin A acid and the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), leads to a gradual disappearance of the 70-kDa protein. We obtained evidence using in situ hybridization that the loss of the 70-kDa keratin is preceded by a specific suppression of the transcription of its putative mRNA in basal cells, whereas initially suprabasal cells are apparently still able to complete their original commitment. The particular properties of the 70-kDa keratin protein, i.e., its topological restriction, its postnatal and time-dependent acquisition, and its pronounced sensitivity to hyperplasiogenic stimuli, make this keratin subunit an especially suitable candidate for studies concerning the regulation of keratin expression and morphogenesis in general, as well as for studies of the factors that control its expression so specifically.

Three cDNA sequences of mouse type I keratins. Cellular localization of the mRNAs in normal and hyperproliferative tissues

We have constructed cDNA libraries with poly(A)+ RNA from normal mouse footpad epidermis and from a squamous cell carcinoma of mouse back skin. Both libraries were screened for type I keratin clones. We present sequence data of three keratin cDNA clones which selected mRNAs coding for two 52-kDa proteins (clones pke 52 and pkSCC 52) as well as for a 50-kDa protein (clone pkSCC50). According to their carboxyl-terminal sequences, the two 52-kDa keratin proteins belong to a group of keratins with serine-rich subdomains adjacent to the alpha-helix, whereas the short carboxyl-terminus of the 50-kDa protein lacks a distinct substructure. Sequentially the two 52-kDa keratins are more closely related to each other than to any other mouse type I keratin. However, in situ hybridization with specific subclones reveals a distinctly different pattern of expression in mouse epithelia. Clone pkSCC 52 contains sequence information for a 52-kDa keratin present in basal cells of epidermis and other stratified epithelia, whereas the pke 52 cDNA encodes a keratin which is predominantly expressed in suprabasal cells of nonepidermal tissues. In terms of nucleotide sequence identities, it cannot precisely be decided which of the two mouse 52-kDa proteins is the equivalent of the human epidermal 50-kDa keratin protein (Hanukoglu, I., and Fuchs, E. (1982) Cell 31, 243-252). In the case of the bovine keratin VII, however (Jorcano, J.L., Rieger, M., Franz, J.K., Schiller, D.L., Moll, R., and Franke, W.W. (1984) J. Mol. Biol. 179, 257-281) the sequence identity values speak for an equivalence with the mouse ke 52 keratin. Obviously, in situ hybridization experiments would best be suited to unravel the precise interspecies relationship between the four highly similar keratins. The discriminatory efficacy of this technique is further emphasized by the demonstration that the mRNA for a 50-kDa keratin is present not only in hyperproliferative epithelia, but also in normal cells of hair follicles.

Differential localization of distinct keratin mRNA-species in mouse tongue epithelium by in situ hybridization with specific cDNA probes

The tongue of the adult mouse is covered by a multilayered squamous epithelium which is continuous on the ventral surface, however interrupted on the dorsal surface by many filiform and few fungiform papillae. The filiform papillae themselves are subdivided into an anterior and posterior unit exhibiting different forms of keratinization. Thus, the entire epithelium shows a pronounced morphological diversity of well recognizable tissue units. We have used a highly sensitive in situ hybridization technique to investigate the differential expression of keratin mRNAs in the tongue epithelium. The hybridization probes used were cDNA restriction fragments complementary to the most specific 3'-regions of any given keratin mRNA. We could show that independent of the morphologically different tongue regions, all basal cells uniformly express the mRNA of a type I 52-kD keratin, typical also for basal cells of the epidermis. Immediately above the homogenous basal layer a vertically oriented specialization of the keratin expression occurs within the morphological tissue units. Thus the dorsal interpapillary and ventral epithelium express the mRNAs of a type II 57-kD and a type I 47-kD keratin pair. In contrast, in the anterior unit of the filiform papillae, only the 47-kD mRNA is present, indicating that this keratin may be coexpressed in tongue epithelium with different type II partners. In suprabasal cells of both, the fungiform papillae and the posterior unit of the filiform papillae, a mRNA of a type I 59-kD keratin could be detected; however, its type II 67-kD epidermal counterpart seems not to be present in these cells. Most surprisingly, in distinct cells of both types of papillae, a type I 50-kD keratin mRNA could be localized which usually is associated with epidermal hyperproliferation. In conclusion, the in situ hybridization technique applied has been proved to be a powerful method for detailed studies of differentiation processes, especially in morphologically complex epithelia.

Aminoalkylsilane-treated glass slides as support for in situ hybridization of keratin cDNAs to frozen tissue sections under varying fixation and pretreatment conditions

Attempts to investigate the cellular localization of keratin mRNAs by in situ hybridization with specific [35S]-labelled cDNA probes to mouse epithelia have been seriously impeded by the uncontrollable detachment of frozen tissue sections on conventionally coated glass slides (i.e. those coated with egg white, gelatin, collagen). Similarly, a variety of other coating and attachment devices have proved to be unsatisfactory or impracticable for large scale investigations. These difficulties were completely overcome and in situ hybridization was possible after a short immersion of the glass slides in a 2% solution of 3-aminopropyltriethoxysilane in acetone. This treatment provides the glass surface with aminoalkyl groups which are apparently able to react covalently with aldehyde or ketone functions of frozen tissue sections. The resulting firm adhesion of the sections enabled us to investigate the influence of different fixation and prehybridization procedures on the quality of the in situ hybridization. It was found that especially harsh prehybridization, involving hydrochloric acid, heat and proteinase K treatment, drastically reduces the morphological integrity of the sections, thus rendering a reliable assignment of the label difficult. In contrast, a mild prehybridization, consisting mainly of a rehydration of the sections in phosphate-buffered saline and equilibration in 0.1 M glycine, leaves the morphology intact and leads to a highly efficient and specific in situ hybridization.

Nonepidermal members of the keratin multigene family: cDNA sequences and in situ localization of the mRNAs

A keratin set which consists of a type I 47kd and a type II 57kd protein occurs as a major constituent of the keratin patterns of various internal stratified epithelia of the mouse. We have isolated specific cDNA clones of the two complementary keratin subunits from a cDNA library constructed with polyA+RNA of mouse tongue epithelium and present the complete nucleotide and deduced amino acid sequences of the 57kd protein and about 75% of the corresponding data of the 47kd protein. The comparison of the sequence data with those of known epidermal keratin mRNAs coding for the two types of keratin proteins reveals a fundamentally identical and type-specific organization of the mRNAs into both highly conserved and variable domains. In order to avoid cross-reactions with other members of the keratin multigene family, appropriately taylored 35S-labeled cDNA probes comprising the low and non-homologous 3' coding and noncoding domains of the mRNAs were used for in situ hybridization to tissue sections. The localization and distribution of the corresponding transcripts indicates a strongly compartmentalized keratin expression in mouse tongue epithelium.