The Regulation of Cell Therapy and Gene Therapy Products in Switzerland

This chapter describes the regulation of cell and gene therapy products (CGTPs) in Switzerland and its legal basis. The Swiss Agency for Therapeutic Products, Swissmedic, is the lead Regulatory Authority and its ATMP Division is responsible for the regulation of these products at the level of clinical trials and marketing authorization. CGTPs are regulated similarly to medicinal products. The legal basis is set by the Therapeutic Product Act, the Transplantation Act, the Human Research Act, and associated ordinances. The ATMP Division is involved in processes such as scientific advice meetings, presubmission advice meetings, pharmacovigilance, market surveillance, import/export approvals, manufacturing license approval, and inspections. In Switzerland, guidance documents relevant for cell and gene therapy provided by PIC/S, OECD, ICH, Ph.Eur., EMA, or FDA are considered. In order to harmonize requirements for CGTPs, the ATMP Division is in constant exchange of information with foreign Regulatory Authorities and part of working groups of ICH, IPRP, and Ph.Eur. As CGTPs are biologically and technically complex, a risk-based approach is applied on a case-by-case basis for the evaluation of clinical trial and marketing applications. A substantial part of this chapter will provide requirements with respect to the manufacturing and quality, nonclinical and clinical evaluation of CGTPs. Furthermore, information will be provided regarding the use of real-world evidence in evaluation of clinical long-term efficacy and safety in case of rare diseases where the numbers of patients are too small for statistically meaningful analysis during clinical trials. Finally, the chapter will provide information on a health technology assessment (HTA) program that was launched in 2015 in Switzerland by the federal authorities.

Radiation-response in primary fibroblasts of long-term survivors of childhood cancer with and without second primary neoplasms: the KiKme study

Background

The etiology and most risk factors for a sporadic first primary neoplasm in childhood or subsequent second primary neoplasms are still unknown. One established causal factor for therapy-associated second primary neoplasms is the exposure to ionizing radiation during radiation therapy as a mainstay of cancer treatment. Second primary neoplasms occur in 8% of all cancer survivors within 30 years after the first diagnosis in Germany, but the underlying factors for intrinsic susceptibilities have not yet been clarified. Thus, the purpose of this nested case–control study was the investigation and comparison of gene expression and affected pathways in primary fibroblasts of childhood cancer survivors with a first primary neoplasm only or with at least one subsequent second primary neoplasm, and controls without neoplasms after exposure to a low and a high dose of ionizing radiation.

Methods

Primary fibroblasts were obtained from skin biopsies from 52 adult donors with a first primary neoplasm in childhood (N1), 52 with at least one additional primary neoplasm (N2+), as well as 52 without cancer (N0) from the KiKme study. Cultured fibroblasts were exposed to a high [2 Gray (Gy)] and a low dose (0.05 Gy) of X-rays. Messenger ribonucleic acid was extracted 4 h after exposure and Illumina-sequenced. Differentially expressed genes (DEGs) were computed using limma for R, selected at a false discovery rate level of 0.05, and further analyzed for pathway enrichment (right-tailed Fisher’s Exact Test) and (in-) activation (z ≥|2|) using Ingenuity Pathway Analysis.

Results

After 0.05 Gy, least DEGs were found in N0 (n = 236), compared to N1 (n = 653) and N2+ (n = 694). The top DEGs with regard to the adjusted p-value were upregulated in fibroblasts across all donor groups (SESN1, MDM2, CDKN1A, TIGAR, BTG2, BLOC1S2, PPM1D, PHLDB3, FBXO22, AEN, TRIAP1, and POLH). Here, we observed activation of p53 Signaling in N0 and to a lesser extent in N1, but not in N2+. Only in N0, DNA (excision-) repair (involved genes: CDKN1A, PPM1D, and DDB2) was predicted to be a downstream function, while molecular networks in N2+ were associated with cancer, as well as injury and abnormalities (among others, downregulation of MSH6, CCNE2, and CHUK). After 2 Gy, the number of DEGs was similar in fibroblasts of all donor groups and genes with the highest absolute log₂ fold-change were upregulated throughout (CDKN1A, TIGAR, HSPA4L, MDM2, BLOC1SD2, PPM1D, SESN1, BTG2, FBXO22, PCNA, and TRIAP1). Here, the p53 Signaling-Pathway was activated in fibroblasts of all donor groups. The Mitotic Roles of Polo Like Kinase-Pathway was inactivated in N1 and N2+. Molecular Mechanisms of Cancer were affected in fibroblasts of all donor groups. P53 was predicted to be an upstream regulator in fibroblasts of all donor groups and E2F1 in N1 and N2+. Results of the downstream analysis were senescence in N0 and N2+, transformation of cells in N0, and no significant effects in N1. Seven genes were differentially expressed in reaction to 2 Gy dependent on the donor group (LINC00601, COBLL1, SESN2, BIN3, TNFRSF10A, EEF1AKNMT, and BTG2).

Conclusion

Our results show dose-dependent differences in the radiation response between N1/N2+ and N0. While mechanisms against genotoxic stress were activated to the same extent after a high dose in all groups, the radiation response was impaired after a low dose in N1/N2+, suggesting an increased risk for adverse effects including carcinogenesis, particularly in N2+.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00520-6.

Identification of Genetic Predispositions Related to Ionizing Radiation in Primary Human Skin Fibroblasts From Survivors of Childhood and Second Primary Cancer as Well as Cancer-Free Controls: Protocol for the Nested Case-Control Study KiKme

BACKGROUND

Therapy for a first primary neoplasm (FPN) in childhood with high doses of ionizing radiation is an established risk factor for second primary neoplasms (SPN). An association between exposure to low doses and childhood cancer is also suggested; however, results are inconsistent. As only subgroups of children with FPNs develop SPNs, an interaction between radiation, genetic, and other risk factors is presumed to influence cancer development.

OBJECTIVE

Therefore, the population-based, nested case-control study KiKme aims to identify differences in genetic predisposition and radiation response between childhood cancer survivors with and without SPNs as well as cancer-free controls.

METHODS

We conducted a population-based, nested case-control study KiKme. Besides questionnaire information, skin biopsies and saliva samples are available. By measuring individual reactions to different exposures to radiation (eg, 0.05 and 2 Gray) in normal somatic cells of the same person, our design enables us to create several exposure scenarios for the same person simultaneously and measure several different molecular markers (eg, DNA, messenger RNA, long noncoding RNA, copy number variation).

RESULTS

Since 2013, 101 of 247 invited SPN patients, 340 of 1729 invited FPN patients, and 150 of 246 invited cancer-free controls were recruited and matched by age and sex. Childhood cancer patients were additionally matched by tumor morphology, year of diagnosis, and age at diagnosis. Participants reported on lifestyle, socioeconomical, and anthropometric factors, as well as on medical radiation history, health, and family history of diseases (n=556). Primary human fibroblasts from skin biopsies of the participants were cultivated (n=499) and cryopreserved (n=3886). DNA was extracted from fibroblasts (n=488) and saliva (n=510).

CONCLUSIONS

This molecular-epidemiological study is the first to combine observational epidemiological research with standardized experimental components in primary human skin fibroblasts to identify genetic predispositions related to ionizing radiation in childhood and SPNs. In the future, fibroblasts of the participants will be used for standardized irradiation experiments, which will inform analysis of the case-control study and vice versa. Differences between participants will be identified using several molecular markers. With its innovative combination of experimental and observational components, this new study will provide valuable data to forward research on radiation-related risk factors in childhood cancer and SPNs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/32395.

Phylogeny of the order Phyllachorales (Ascomycota, Sordariomycetes): among and within order relationships based on five molecular loci

The order Phyllachorales (Pezizomycotina, Ascomycota) is a group of biotrophic, obligate plant parasitic fungi with a tropical distribution and high host specificity. Traditionally two families are recognised within this order: Phyllachoraceae and Phaeochoraceae, based mostly on morphological and host characteristics. Currently, the position of the order within the class Sordariomycetes is inconclusive, as well as the monophyly of the order, and its internal phylogenetic structure. Here we present a phylogeny of the order Phyllachorales based on sequence data of 29 species with a broad host range resulting from a wide geographical sampling. We inferred Maximum Likelihood and Bayesian phylogenies from data of five DNA regions: nrLSU rDNA, nrSSU rDNA, ITS rDNA, and the protein coding genes RPB2, and TEF1. We found that the order Phyllachorales is monophyletic and related to members of the subclass Sordariomycetidae within Sordariomycetes. Within the order, members of the family Phaeochoraceae form a monophyletic group, and the family Phyllachoraceae is split into two lineages. Maximum Likelihood ancestral state reconstructions indicate that the ancestor of Phyllachorales had a monocotyledonous host plant, immersed perithecia, and a black stroma. Alternative states of these characters evolved multiple times independently within the order. Based on our results we redefine the family Phyllachoraceae and propose the new family Telimenaceae with Telimena erythrinae as type species, resulting in three families in the order. Species of Telimena spp. occur in several monocotyledonous and eudicotyledonous host plants except Poaceae, and generally have enlarged black pseudostroma around the perithecia, a character not present in species of Phyllachoraceae.

Cyclooxygenase-2 controls energy homeostasis in mice by de novo recruitment of brown adipocytes

Obesity results from chronic energy surplus and excess lipid storage in white adipose tissue (WAT). In contrast, brown adipose tissue (BAT) efficiently burns lipids through adaptive thermogenesis. Studying mouse models, we show that cyclooxygenase (COX)-2, a rate-limiting enzyme in prostaglandin (PG) synthesis, is a downstream effector of beta-adrenergic signaling in WAT and is required for the induction of BAT in WAT depots. PG shifted the differentiation of defined mesenchymal progenitors toward a brown adipocyte phenotype. Overexpression of COX-2 in WAT induced de novo BAT recruitment in WAT, increased systemic energy expenditure, and protected mice against high-fat diet-induced obesity. Thus, COX-2 appears integral to de novo BAT recruitment, which suggests that the PG pathway regulates systemic energy homeostasis.

An isoform of ataxin-3 accumulates in the nucleus of neuronal cells in affected brain regions of SCA3 patients

Autosomal dominant spinocerebellar ataxias (SCA) form a group of clinically and genetically heterogeneous neurodegenerative disorders. The defect responsible for SCA3/Machado-Joseph disease (MJD) has been identified as an unstable and expanded (CAG)n trinucleotide repeat in the coding region of a novel gene of unknown function. The MJD1 gene product, ataxin-3, exists in several isoforms. We generated polyclonal antisera against an alternate carboxy terminus of ataxin-3. This isoform, ataxin-3c, is expressed as a protein of approximately 42 kDa in normal individuals but is significantly enlarged in affected patients confirming that the CAG repeat is part of the ataxin-3c isoform and is translated into a polyglutamine stretch, a feature common to all known CAG repeat disorders. Ataxin-3 like immunoreactivity was observed in all human brain regions and peripheral organs studied. In neuronal cells of control individuals, ataxin-3c was expressed cytoplasmatically and had a somatodendritic and axonal distribution. In SCA3 patients, however, C-terminal ataxin-3c antibodies as well as anti-ataxin-3 monoclonal antibodies (1 H9) and anti-ubiquitin antibodies detected intranuclear inclusions (NIs) in neuronal cells of affected brain regions. A monoclonal antibody, 2B6, directed against an internal part of the protein, barely detected these NIs implying proteolytic cleavage of ataxin-3 prior to its transport into the nucleus. These findings provide evidence that the alternate isoform of ataxin-3 is involved in the pathogenesis of SCA3/MJD. Intranuclear protein aggregates appear as a common feature of neurodegenerative polyglutamine disorders.

Polymorphisms of the alpha-synuclein promoter: expression analyses and association studies in Parkinson's disease

Mutations of the alpha-synuclein gene have shown to be relevant in some rare families with autosomal dominant Parkinson's disease (PD). Furthermore, alpha-synuclein protein is a major component of the Lewy bodies also in sporadic PD patients. Increased levels of wildtype alpha-synuclein in the cell leads to increased intracellular hydrogen peroxide levels and causes death of dopaminergic neurons in rat primary culture. Subsequently, oxidative stress has been directly linked with alpha-synuclein aggregation in vitro. This raises the question whether increased alpha-synuclein expression might be linked to higher susceptibility to PD and whether alpha-synuclein promoter polymorphisms are associated with PD. Here, two polymorphisms (-116C>G and -668T>C) of the alpha-synuclein promoter defining four haplotypes have been characterized in 315 German PD patients. The influence of the four haplotypes on gene expression was studied by CAT reporter gene assays in neuronal SK-N-AS cells. The -668C/-116G haplotype revealed significant higher CAT expression than the -668T/-116G or the -668T/-116C haplotype, respectively. Although the -668C/-116G haplotype was more common in PD patients, this difference was not significant.

Physical interaction of human T-cell leukemia virus type 1 Tax with cyclin-dependent kinase 4 stimulates the phosphorylation of retinoblastoma protein

The Tax oncoprotein of human T-cell leukemia virus type 1 (HTLV-1) induces leukemia in transgenic mice and permanent T-cell growth in vitro. In transformed lymphocytes, it acts as an essential growth factor. Tax stimulates the cell cycle in the G(1) phase by activating the cyclin-dependent kinase (CDK) CDK4 and CDK6 holoenzyme complexes. Here we show that Tax directly interacts with CDK4. This binding to CDK4 was specific, since Tax did not bind to either CDK2 or CDK1. The interaction with CDK4/cyclin D complexes was observed in vitro, in transfected fibroblasts, in HTLV-1-infected T cells, and in adult T-cell leukemia-derived cultures. Binding studies with several point and deletion mutants indicated that the N terminus of Tax mediates the interaction with CDK4. The Tax/CDK complex represented an active holoenzyme which capably phosphorylates the Rb protein in vitro and is resistant to repression by the inhibitor p21(CIP). Binding-deficient Tax mutants failed to activate CDK4, indicating that direct association with Tax is required for enhanced kinase activity. Tax also increased the association of CDK4 with its positive cyclin regulatory subunit. Thus, protein-protein contact between Tax and the components of the cyclin D/CDK complexes provides a further mechanistic explanation for the mitogenic and immortalizing effects of this HTLV-1 oncoprotein.

A novel lentivirus vector derived from apathogenic simian immunodeficiency virus

The improvement of gene transfer efficiency in growth-arrested cells using human immunodeficiency virus type 1 (HIV-1)-derived vectors led to the development of vectors derived from other members of the lentivirus family. Here we report the generation of a lentiviral vector derived from the apathogenic molecular virus clone SIVagm3mc of the simian immunodeficiency virus from African green monkeys (Cercocebus pygerythrus). Upon pseudotyping with the G-protein of vesicular stomatitis virus (VSV-G), the SIVagm-derived vector was shown to transduce proliferating and growth-arrested mammalian cell lines, including human cells. After in vivo inoculation into the striatum of the adult rat brain, the vector was shown to transduce terminally differentiated neurons and oligodendrocytes as well as quiescent and reactive astrocytes. Moreover, SIVagm transfer vector mRNA was efficiently packaged by HIV-1 vector particles. Homologous [SIV(SIV)] vectors generated by using the SIVagm-derived envelope glycoproteins allowed selective gene transfer into human CD4(+)/CCR5(+) cells. Thus, the SIVagm3mc-derived vector is a useful alternative to HIV-1-derived lentiviral vectors in somatic gene therapy.

In vitro analysis of nuclear transport mediated by the C-terminal shuttle domain of Tap

The Tap protein of higher eukaryotes is implicated in the nuclear export of type D retroviral mRNA and some cellular mRNAs. Here we have developed an in vitro assay to study nuclear export mediated by the C-terminal shuttle domain of Tap involving the rapamycin-induced attachment of this transport domain to a nuclear green fluorescent protein-containing reporter. We found that export by the Tap transport domain does not involve cytosolic transport factors including the GTPase Ran. The transport domain directly binds to several nucleoporins positioned in different regions of the nuclear pore complex. These results argue that a direct interaction of the Tap transport domain with nucleoporins is responsible for its nucleocytoplasmic translocation. We found that the karyopherin beta-related export receptor CRM1 competes with the Tap transport domain for binding to Nup214 but not for binding to Nup62 or Nup153, suggesting that the Tap and CRM1 nuclear export pathways converge at the cytoplasmic periphery of the nuclear pore complex. Because the rates of in vitro nuclear import and export by the Tap transport domain are very similar, the directionality of mRNA export mediated by Tap probably is determined by mechanisms other than simple binding of the Tap transport domain to nucleoporins.

Inflammatory genes are upregulated in expanded ataxin-3-expressing cell lines and spinocerebellar ataxia type 3 brains

Spinocerebellar ataxia type 3 (SCA3) is a polyglutamine disorder caused by a CAG repeat expansion in the coding region of a gene encoding ataxin-3. To study putative alterations of gene expression induced by expanded ataxin-3, we performed PCR-based cDNA subtractive hybridization in a cell culture model of SCA3. In rat mesencephalic CSM14.1 cells stably expressing expanded ataxin-3, we found a significant upregulation of mRNAs encoding the endopeptidase matrix metalloproteinase 2 (MMP-2), the transmembrane protein amyloid precursor protein, the interleukin-1 receptor-related Fos-inducible transcript, and the cytokine stromal cell-derived factor 1alpha (SDF1alpha). Immunohistochemical studies of the corresponding or associated proteins in human SCA3 brain tissue confirmed these findings, showing increased expression of MMP-2 and amyloid beta-protein (Abeta) in pontine neurons containing nuclear inclusions. In addition, extracellular Abeta-immunoreactive deposits were detected in human SCA3 pons. Furthermore, pontine neurons of SCA3 brains strongly expressed the antiinflammatory interleukin-1 receptor antagonist, the proinflammatory cytokine interleukin-1beta, and the proinflammatory chemokine SDF1. Finally, increased numbers of reactive astrocytes and activated microglial cells were found in SCA3 pons. These results suggest that inflammatory processes are involved in the pathogenesis of SCA3.

Cofactor requirements for nuclear export of Rev response element (RRE)- and constitutive transport element (CTE)-containing retroviral RNAs. An unexpected role for actin

Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the export receptor CRM1/exportin1. However, additional protein factors interacting with leucine-rich NESs have been described. Here, we investigate human immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export and Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE)-mediated nuclear export in microinjected Xenopus laevis oocytes. We show that eukaryotic initiation factor 5A (eIF-5A) is essential for Rev and Rev-mediated viral RNA export, but not for nuclear export of CTE RNA. In vitro binding studies demonstrate that eIF-5A is required for efficient interaction of Rev-NES with CRM1/exportin1 and that eIF-5A interacts with the nucleoporins CAN/nup214, nup153, nup98, and nup62. Quite unexpectedly, nuclear actin was also identified as an eIF-5A binding protein. We show that actin is associated with the nucleoplasmic filaments of nuclear pore complexes and is critically involved in export processes. Finally, actin- and energy-dependent nuclear export of HIV-1 Rev is reconstituted by using a novel in vitro egg extract system. In summary, our data provide evidence that actin plays an important functional role in nuclear export not only of retroviral RNAs but also of host proteins such as protein kinase inhibitor (PKI).

Tax-dependent stimulation of G1 phase-specific cyclin-dependent kinases and increased expression of signal transduction genes characterize HTLV type 1-transformed T cells

Human T cell leukemia virus protein induces T cells to permanent IL-2-dependent growth. These cells occasionally convert to factor independence. The viral oncoprotein Tax acts as an essential growth factor of transformed lymphocytes and stimulates the cell cycle in the G(1) phase. In T cells and fibroblasts Tax enhances the activity of the cyclin-dependent kinases (CDK) CDK4 and CDK6. These kinases, which require binding to cyclin D isotypes for their activity, control the G(1) phase. Coimmunoprecipitation from these cells revealed that Tax associates with cyclin D3/CDK6, suggesting a direct activation of this kinase. The CDK stimulation may account in part for the mitogenic Tax effect, which causes IL-2-dependent T cell growth by Tax. To address the conversion to IL-2-independent proliferation and to identify overexpressed genes, which contribute to the transformed growth, the gene expression patterns of HTLV-1-transformed T cells were compared with that of peripheral blood lymphocytes. Potentially overexpressed cDNAs were cloned, sequenced, and used to determine the RNA expression. Genes found to be up-regulated are involved in signal transduction (STAT5a, cyclin G(1), c-fgr, hPGT) and also glycoprotein synthesis (LDLC, ribophorin). Many of these are also activated during T cell activation and implicated in the regulation of growth and apoptosis. The transcription factor STAT5a, which is involved in IL-2 signaling, was strongly up-regulated only in IL-2-independent cells, thus suggesting that it contributes to factor-independent growth. Thus, the differentially expressed genes could cooperate with the Tax-induced cell cycle stimulation in the maintenance of IL-2-dependent and IL-2-independent growth of HTLV-transformed lymphocytes.

Lentiviral vectors pseudotyped with envelope glycoproteins derived from gibbon ape leukemia virus and murine leukemia virus 10A1

Lentiviral vectors pseudotyped with the envelope glycoproteins (Env) of amphotropic murine leukemia virus (MLV) and the G protein of vesicular stomatitis virus (VSV-G) have been successfully used in recent preclinical gene therapy studies. We report here the generation of infectious HIV-1-derived vector particles pseudotyped with the Env of the molecular clone 10A1 of MLV and with chimeric envelope glycoprotein variants derived from gibbon ape leukemia virus (GaLV) and MLV. Formation of infectious HIV-1 (GaLV) pseudotype vectors was only possible with the substitution of the cytoplasmic tail of GaLV Env with that of MLV. The lentiviral vectors exhibited a host cell range identical with that of MLV(GaLV) and MLV(10A1) vectors, which are known to enter cells either via the GaLV-receptor Glvr-1 (Pit-1) or via the amphotropic receptor Ram-1 (Pit-2) in addition to Glvr-1, respectively. Thus, HIV-1(GaLV) and HIV-1(10A1) pseudotype vectors may be useful for efficient gene transfer into a variety of human tissues like primary human hematopoietic cells.

MLV-derived retroviral vectors selective for CD4-expressing cells and resistant to neutralization by sera from HIV-infected patients

Retroviral vectors derived from amphotropic murine leukemia viruses (MLV) mediate gene transfer into almost all human cells and are thus not suitable for in vivo applications in gene therapy in which cell-specific gene delivery is required. We and others recently reported the generation of MLV-derived vectors pseudotyped by variants of the envelope glycoproteins (Env) of human immunodeficiency virus type 1 (HIV-1), thus displaying the CD4-dependent tropism of the parental lentivirus (Mammano et al., 1997, J. Virol. 71, 3341-3345; Schnierle et al., 1997, Proc. Natl. Acad. Sci. USA 76, 8640-8645). However, because of their HIV-1-derived envelopes these vectors are neutralized by HIV-specific antibodies present in some infected patients. To circumvent this problem, we pseudotyped MLV capsid particles with variants of Env proteins derived from the apathogenic simian immunodeficiency virus (SIVagm) of African green monkeys (AGM; Chlorocebus pygerythrus). Truncation of the C-terminal domain of the transmembrane protein was found to be necessary to allow formation of infectious pseudotype vectors. These [MLV(SIVagm)] vectors efficiently transduced various human CD4-expressing cell lines using the coreceptors CCR5 and Bonzo to enter target cells. Moreover, they were resistant to neutralization by antibodies directed against HIV-1. Therefore, [MLV(SIVagm)] vectors will be useful to study the mechanisms of SIVagm cell entry and for the selective gene transfer into CD4+ T-cells of AIDS patients.

Genetic variation of Usnea filipendula (Parmeliaceae) populations in western Germany investigated by RAPDs suggests reinvasion from various sources

Random amplified polymorphic DNA (RAPD) markers were characterized for 25 specimens of Usnea filipendula to evaluate the genetic diversity of populations reinvading formerly uninhabited regions in Northrhine-Westphalia due to decreasing sulfur dioxide levels. With six 10-mer randomly amplified polymorphic DNA (RAPD) primers, a 66 character by 25 specimens matrix was generated. Phenetic analysis (UPGMA) showed no obvious groupings. The reinvading populations are distributed over the phenogram and are not genetically closely related. The results suggest that the reinvading populations of this usually sterile species are derived from different sources and do not consist of a particular clone capable of re-entering the area.

Human T-cell leukemia virus type 1 Tax and cell cycle progression: role of cyclin D-cdk and p110Rb

Human T-cell leukemia virus type 1 is etiologically linked to the development of adult T-cell leukemia and various human neuropathies. The Tax protein of human T-cell leukemia virus type I has been implicated in cellular transformation. Like other oncoproteins, such as Myc, Jun, and Fos, Tax is a transcriptional activator. How it mechanistically dysregulates the cell cycle is unclear. Previously, it was suggested that Tax affects cell-phase transition by forming a direct protein-protein complex with p16(INK4a), thereby inactivating an inhibitor of G1-to-S-phase progression. Here we show that, in T cells deleted for p16(INK4a), Tax can compel an egress of cells from G0/G1 into S despite the absence of serum. We also show that in undifferentiated myocytes, expression of Tax represses cellular differentiation. In both settings, Tax expression was found to increase cyclin D-cdk activity and to enhance pRb phosphorylation. In T cells, a Tax-associated increase in steady-state E2F2 protein was also documented. In searching for a molecular explanation for these observations, we found that Tax forms a protein-protein complex with cyclin D3, whereas a point-mutated and transcriptionally inert Tax mutant failed to form such a complex. Interestingly, expression of wild-type Tax protein in cells was also correlated with the induction of a novel hyperphosphorylated cyclin D3 protein. Taken together, these findings suggest that Tax might directly influence cyclin D-cdk activity and function, perhaps by a route independent of cdk inhibitors such as p16(INK4a).

A human T-cell leukemia virus Tax variant incapable of activating NF-kappaB retains its immortalizing potential for primary T-lymphocytes

The human T-cell leukemia virus type 1 (HTLV-1) transactivator (Tax) has been shown to interfere with regulated cellular proliferation. Many studies have focused on the ability of Tax to transform rodent fibroblasts; however, none has defined the molecular requirements for Tax transformation of human lymphoid cells. We show here that tax induces permanent growth of human primary T-lymphocytes by using a transformation/immortalization defective rhadinovirus vector. The cells phenotypically resemble HTLV-immortalized lymphocytes and contain episomally persisting recombinant rhadinoviral sequences, which stably express functional Tax protein. As Tax can activate major cellular signal transducing pathways including NF-kappaB and cAMP-responsive element binding protein (CREB), we asked for the relevance of these routes in the immortalization of human lymphocytes. By using Tax mutants that either activate exclusively CREB/activating transcription factor or are defective in activating this signaling pathway, we delineated that Tax can induce immortalization of primary human T-lymphocytes through a mechanism independent of NF-kappaB activation.

Stimulation of cyclin-dependent kinase activity and G1- to S-phase transition in human lymphocytes by the human T-cell leukemia/lymphotropic virus type 1 Tax protein

The human T-cell leukemia/lymphotropic virus type 1 (HTLV-1) induces a malignant lymphocytic disease. The HTLV-1 transactivator protein, Tax, is believed to be crucial for the development of the disease since it is transforming in vitro and induces tumors in transgenic animals. Although the transcriptional modulation of viral and cellular gene expression by Tax has been analyzed thoroughly, it has remained unclear how the Tax functions act on the cell cycle of primary T cells. To investigate the mechanism of Tax-mediated T-cell stimulation, we transduced primary human cord blood T cells with a conditional, tetracycline repressor-based tax expression system. Permanent Tax expression results in an abnormal proliferation of T cells which closely resemble HTLV-1-infected lymphocytes. Suppression of Tax synthesis stopped lymphocyte growth and caused cell cycle arrest in the G1 phase. Upon reinduction of tax expression, the arrested cells entered the S phase. This showed that Tax has mitogenic activity, which is required for stimulating the G1- to S-phase transition of immortalized lymphocytes. In mammalian cells, the G1-phase progression is controlled by the serial activation of several cyclin-dependent kinases (Cdks), starting with Cdk4 and Cdk6. In the presence of Tax, both Cdk4 and Cdk6 were activated. The suppression of Tax synthesis, however, resulted in a significant reduction of the Cdk4 and Cdk6 activities but did not influence the expression of Cdk4, Cdk6, or cognate D-type cyclin proteins. These data suggest that Tax induces Cdk4 and Cdk6 activity in primary human T lymphocytes; this Cdk activation is likely to account for the mitogenic Tax effect and for the abnormal T-cell proliferation of HTLV-1-infected lymphocytes.

Cutaneous epithelioid cell histiocytoma: immunohistochemical and ultrastructural findings suggesting endothelial origin

A 13-year-old boy presented with a polypoid nodule localized in the groin. Although the clinical and histopathological features corresponded to previously described diagnostic criteria of epithelioid cell histiocytoma, immunohistochemical and ultrastructural findings suggested vascular differentiation of the epithelioid cells. In particular, the immunohistochemical negativity of the epithelioid cell elements for Factor XIIIa failed to substantiate the previously forwarded hypothesis that this lesion represents a dendrocytoma. Instead, the presence of histiocytoid, vacuolated cells occasionally containing sparse red blood cells, positive staining for Factor VIII-related antigen, and ultrastructural evidence of endothelial characteristics in epithelioid neoplastic cells favor the hypothesis that "epithelioid cell histiocytoma" is of endothelial origin. We suggest the descriptive term cutaneous histiocytoid hemangioendothelioma for this lesion.

Characterization of the rat spinocerebellar ataxia type 3 gene

Machado-Joseph disease (MJD) belongs to a group of clinically and genetically heterogeneous neurodegenerative disorders characterized by progressive cerebellar ataxia. The disease-causing mutation has recently been identified as an unstable and expanded (CAG)n trinucleotide repeat in a novel gene of unknown function. In Caucasians, repeat expansions in the MJD1 gene have also been found in patients with the clinically distinct autosomal dominant spinocerebellar ataxia type 3 (SCA3). In order to gain insight into the biology of the MJD1/SCA3 gene we cloned the rat homologue and studied its expression. The rat and human ataxin-3 genes are highly homologous with an overall sequence identity of approximately 88%. However, the C-terminal end of the putative protein differs strongly from the published human sequence. The (CAG)n block in the rat cDNA consists of just three interrupted units suggesting that a long polyglutamine stretch is not essential for the normal function of the ataxin-3 protein in rodents. The expression pattern of the SCA3 gene in various rat and human tissues was investigated by Northern blot analyses. The mature transcript is approximately 6 kb in length. In rat testis, a smaller transcript of 1.3 kb was identified. Transcription of rsca3 was detected in most rat tissues including brain. Analyzing the expression level of the SCA3 gene in several human brain sections revealed no significant higher mRNA level in regions predominantly affected in MJD. Thus additional molecules and/or regulatory events are necessary to explain the exclusive degeneration of certain brain areas.

Indeterminate cell histiocytosis: a rare histiocytic disorder

A 64-year-old woman, otherwise healthy, presented with multiple reddish-brown, slightly yellowish papules on the face and neck, which had developed 3 years earlier. The lesions were painless and nonpruritic and varied in diameter from 1 to 5 mm. Histological and immunohistochemical examination of cutaneous biopsies revealed a diffuse dermal infiltrate composed mainly of histiocytes which expressed both Langerhans cell as well as monocytic/macrophages cell marker characteristics. Electron microscopic studies revealed no Birbeck granules within the cytoplasm of the neoplastic cells, leading to a diagnosis of indeterminate cell histiocytosis. Indeterminate cell histiocytosis is a very rare disease characterized by the proliferation of indeterminate histiocytes which morphologically and immunophenotypically resemble Langerhans cells but lack Birbeck granules.

Induction of functional empty class I major histocompatibility complex glycoproteins by photoactivated 8-methoxypsoralen

CD8+ cytotoxic T lymphocytes (CTLs) bind to and selectively lyse tumor cells via T-cell receptor recognition of distinctive peptide antigens presented in the context of surface major histocompatibility complex class I (MHC class I) glycoproteins. Several human and experimental animal tumors express distinctive MHC class I-associated peptides, which can be selectively targeted by specific CD8+ CTLs. Malignant cells expressing low quantities of these peptides are poor inducers of CTL responses. Therefore, we have developed a method of externally loading increased amounts of antigenic peptides onto MHC class I molecules. In order to induce "empty" fillable MHC class I molecules capable of binding antigenic peptides, we exposed transformed murine T cells (RMA) to low dose (3 joules/cm2) ultraviolet A energy and 8-methoxypsoralen (100 ng per ml). Presence of "empty" class I molecules was ascertained by "meltdown" or loss of the thermodynamically unstable cold-induced "empty" molecules as identified by cytofluorography at 37 degrees C. Retained function of "empty" molecules was determined by their stabilization through addition of peptides of the correct size and sequence motif, prior to exposure to physiologic temperature.

cDNA cloning and expression of rsca1, the rat counterpart of the human spinocerebellar ataxia type 1 gene

Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disorder caused by an expanded and unstable (CAG) > 40 repeat within a gene of unknown function. We isolated the complete coding region of the rat SCA1 gene (rsca1), the 5'-untranslated region (UTR) and 1.3 kb of the 3'-UTR. The rat sequence exhibits 90% peptide identity to the human counterpart. In comparison to human, the rat (CAG)n block is reduced to two trinucleotide motifs preceded by three different proline codons not present in man. Furthermore, we investigated the expression of rsca1 in different rat tissues. The rsca1 gene is predominantly expressed in brain throughout all developmental stages. In situ hybridizations reveal high levels of expression in various regions of the adult rat brain, including cerebellum, hippocampus and cortex.

Predominant neuronal expression of the gene responsible for dentatorubral-pallidoluysian atrophy (DRPLA) in rat

Dentatorubral and pallidoluysian atrophy (DRPLA) belongs to a group of trinucleotide diseases in humans associated with an expanded and unstable (CAG) > 49 repeat within a gene of unknown function. Clinically, DRPLA presents with variable combinations of myoclonus, epilepsy, cerebellar ataxia, choreoathetosis and dementia. Hardly anything is known about the physiological function of the DRPLA gene and the pathological mechanisms causing neuronal cell death and leading to these symptoms. To analyze some of these aspects of the DRPLA gene we isolated the complete coding region of the rat DRPLA gene (rdrpla) and investigated its expression in different developmental stages of rodent tissues. The rdrpla gene shows 92% homology in amino acid sequence to the human gene. In rat the length of the (CAG)n repeat is reduced compared to the human (CAG)n block containing 7-34 repeats with an average of 15. Northern blot analysis revealed that in rodents the rdrpla gene is already expressed during embryo development. In addition this transcript is predominantly represented in neuronal tissues throughout all developmental stages investigated.

Assignment of the dystonia-parkinsonism syndrome locus, DYT3, to a small region within a 1.8-Mb YAC contig of Xq13.1

A YAC contig was constructed of Xq13.1 in order to sublocalize the X-linked dystonia-parkinsonism (XDP) syndrome locus, DYT3. The contig spans a region of approximately 1.8 Mb and includes loci DXS453/DXS348/IL2R gamma/GJB1/CCG1/DXS559. For the construction of the contig, nine sequence-tagged sites and four short tandem repeat polymorphisms (STRPs) were isolated. The STRPs, designated as 4704#6 (DXS7113), 4704#7 (DXS7114), 67601 (DXS7117), and B4Pst (DXS7119) were assigned to a region flanked by DXS348 proximally and by DXS559 distally. Their order was DXS348/4704 #6/4704 #7/67601/B4Pst/DXS559. They were applied to the analysis of allelic association and of haplotypes in 47 not-obviously-related XDP patients and in 105 Filipino male controls. The same haplotype was found at loci 67601 (DXS7117) and B4Pst (DXS7119) in 42 of 47 patients. This percentage of common haplotypes decreased at the adjacent loci. The findings, together with the previous demonstration of DXS559 being the distal flanking marker of DYT3, assign the disease locus to a small region in Xq13.1 defined by loci 67601 (DXS7117) and B4Pst (DXS7119). The location of DYT3 was born out by the application of a newly developed likelihood method for the analysis of linkage disequilibrium.

Expression of the Huntington disease gene in rodents: cloning the rat homologue and evidence for downregulation in non-neuronal tissues during development

Huntington's disease (HD) is associated with an expanded and unstable (CAG) > 35 repeat within a gene of unknown function. We isolated the complete coding region of the rat HD gene (rhd) from cDNA libraries and investigated its expression in different developmental stages of rodent tissues. The rat gene exhibits 90% peptide sequence identity to the human and 96% to the murine sequence. The (CAG)n repeat is markedly reduced in the rat compared to the average human (CAG)n block. Northern blot analysis and in situ hybridizations reveal that in rodents the hd gene is already expressed during embryonal development. As in humans, the rhd gene is expressed in two transcriptional isoforms which result from different polyadenylation signals. In mice, however, a third transcript of intermediate size was found predominantly expressed in brain. This transcript is downregulated in later development. At day 14.5 p.c. the level of rhd expression is similar in the brain and in non-neuronal tissues. In contrast, the expression in non-neuronal tissues is markedly reduced in adult animals and corresponds to the restricted distribution of neuropathologic changes observed in HD patients.

Molecular genetics of inherited diseases involving human chromosome 4

Two molecular genetic strategies have widely been employed to characterize candidate genes for human inherited diseases; identification of disease genes via positional cloning and characterization of altered candidate genes in affected persons. Both approaches allowed to uncover disease genes. A well-known example for positional cloning is the identification of the Huntington's disease (HD) gene on human chromosome 4. In other diseases such as piebaldism, Hurler/Scheie syndrome and a form of autosomal recessive retinitis pigmentosa, the disease gene has first been analyzed and later been localized to human chromosome 4. Steady progress in the human genome project permits to combine affected families pointing to the chromosomal localization of the disease causing defects. Then the genes are investigated that are already mapped to this particular region. Accordingly the achondrodysplasia gene has been identified within six months after its chromosomal localization. In order to evaluate cloned genes as potential candidates for disorders linked to chromosome 4, it is important to assign all genes to chromosomal (sub)regions. Furthermore in excess of 140 closely spaced microsatellites on chromosome 4 as well as many "expressed sequence tags" will help to narrow in on additional disease genes.

Characterization of the gene for human neutrophil-activating peptide 78 (ENA-78)

The genomic DNA for ENA-78 has been obtained from a human chromosome 4 flow-sorted cosmid library. Three out of 25,000 screened single colonies yielded the same 2.2-kB EcoRI ENA-78 gene fragment. A similar size fragment was observed on genomic southern blots, suggesting the presence of a single ENA-78 gene. The transcriptional start site was localized using a 5' RACE protocol on first strand cDNA prepared from stimulated alveolar type-II epithelial cell (A549) poly(A) mRNA. The ENA-78 gene contains four exons and three introns and the open reading frame of 342 nucleotides encodes for a protein of total 114 amino acids. The 5' flanking region contains potential binding sites for several nuclear factors such as AP-2, NF-kappa B, and interferon regulatory factor-1.

[Studies on the viability of pathogenic amebae of the genus Naegleria in water of different sources (author's transl)]

Water specimens taken from the public water supply (A), a swimming-pool (B), and an inland lake (C) were infected with pathogenic amebae of the genus Naegleria (strain TY/Richmond). The specimens were stored at various temperatures for different periods. The water was then filtered and examined for naegleriae by animal inoculation. The results summarized in table 1 indicate that pathogenic naegleriae are viable at least for some weeks in warm tap and natural waters. Water from indoor swimming-pools however, may be a less suitable medium for the viability of pathogenic naegleriae.

[Diagnostic significance of identification of anti-entamoeba histolytica antibodies (author's transl)]

Examinations were performed with the indirect immunofluorescence test (IFAT) and the indirect haemagglutination test (IHAT). Negative titers (less than 1:5) do not exclude an infection with E. histolytica. Titers up to 1:80 in both reactions are found in patients with negative stool specimens or indicate an asymptomatic infection of the intestinal lumen, an incipient or past symptomatic amoebiasis. IFAT values of 1:160 together with a negative or positive IHAT are also suggestive of the two last-mentioned types of infection. These titers are also found in patients with gastrointestinal disorders of other orgin. IFAT values higher than 1:60 with a positive IHAT are probably due to an invasive amoebiasis. Titres are, however, only diagnostic pointers.