Maria Sibilia

Loss of the Suv39h Histone Methyltransferases Impairs Mammalian Heterochromatin and Genome Stability

Histone H3 lysine 9 methylation has been proposed to provide a major switch for the functional organization of chromosomal subdomains. Here, we show that the murine Suv39h histone methyltransferases (HMTases) govern H3-K9 methylation at pericentric heterochromatin and induce a specialized histone methylation pattern that differs from the broad H3-K9 methylation present at other chromosomal regions. Suv39h-deficient mice display severely impaired viability and chromosomal instabilities that are associated with an increased tumor risk and perturbed chromosome interactions during male meiosis. These in vivo data assign a crucial role for pericentric H3-K9 methylation in protecting genome stability, and define the Suv39h HMTases as important epigenetic regulators for mammalian development.

Amino-terminal phosphorylation of c-Jun regulates stress-induced apoptosis and cellular proliferation.

c-Jun is a major component of the heterodimeric transcription factor AP-1 and is essential for embryonic development, as fetuses lacking Jun die at mid-gestation1,2 with impaired hepatogenesis and primary Jun–/– fibroblasts have a severe proliferation defect and undergo premature senescence in vitro. c-Jun and AP-1 activities are regulated by c-Jun N-terminal phosphorylation (JNP) at serines 63 and 73 through Jun N-terminal kinases (JNKs). JNP is thought to be required for the anti-apoptotic function of c-Jun during hepatogenesis, as mice lacking the JNK kinase SEK1 exhibit liver defects similar to those seen in Jun–/– fetuses. To investigate the physiological relevance of JNP, we replaced endogenous Jun by a mutant Jun allele with serines 63 and 73 mutated to alanines (Juntm1Wag; hereafter referred to as JunAA). Here we show that primary JunAA fibroblasts have proliferation- and stress-induced apoptotic defects, accompanied by reduced AP-1 activity. JunAA mice are viable and fertile, smaller than controls and resistant to epileptic seizures and neuronal apoptosis induced by the excitatory amino acid kainate. Primary mutant neurons are also protected from apoptosis and exhibit unaltered JNK activity. Our results provide evidence that JNP is dispensable for mouse development, and identify c-Jun as the essential substrate of JNK signalling during kainate-induced neuronal apoptosis.

The EGF Receptor Provides an Essential Survival Signal for SOS-Dependent Skin Tumor Development

The EGF receptor (EGFR) is required for skin development and is implicated in epithelial tumor formation. Transgenic mice expressing a dominant form of Son of Sevenless (SOS-F) in basal keratinocytes develop skin papillomas with 100% penetrance. However, tumor formation is inhibited in a hypomorphic (wa2) and null EGFR background. Similarly, EGFR-deficient fibroblasts are resistant to transformation by SOS-F and rasV12, however, tumorigenicity is restored by expression of the anti-apoptotic bcl-2 gene. The K5-SOS-F papillomas and primary keratinocytesfrom wa2 mice display increased apoptosis, reduced Akt phosphorylation and grafting experiments imply a cell-autonomous requirement for EGFR in keratinocytes. Therefore, EGFR functions as a survival factor in oncogenic transformation and provides a valuable target for therapeutic intervention in a broader range of tumors than anticipated.

A strain‐independent postnatal neurodegeneration in mice lacking the EGF receptor

Mice lacking the epidermal growth factor receptor (EGFR) exhibit strain‐dependent phenotypes ranging from placental to postnatal skin, lung and brain defects. After birth, all mutant mice develop a progressive neurodegeneration in the frontal cortex, olfactory bulb and thalamus, characterized by massive apoptosis and upregulation of c‐fos. These defects occur in a strain‐independent manner, since neither rescue of the placental phenotype by aggregation of diploid 129/Sv EGFR mutant and tetraploid wild‐type embryos, nor promotion of lung maturation by transplacental dexamethasone administration alters the course of neurodegeneration. VEGF is not induced during the degenerative process, excluding hypoxia and ischemia as causes of cell death. A migratory disorder is detected in the hippocampus with nests of ectopic neurons, which are also apoptotic. Cerebral cortices from EGFR mutants contain lower numbers of GFAP positive astrocytes, which display reduced proliferation in vitro. Since EGFR is expressed in the affected cell‐types, these results define a specific function for EGFR in the proliferation and/or differentiation of astrocytes and in the survival of postmitotic neurons.

c-Jun Regulates Eyelid Closure and Skin Tumor Development through EGFR Signaling

To investigate the function of c-Jun during skin development and skin tumor formation, we conditionally inactivated c-jun in the epidermis. Mice lacking c-jun in keratinocytes (c-jun(Deltaep)) develop normal skin but express reduced levels of EGFR in the eyelids, leading to open eyes at birth, as observed in EGFR null mice. Primary keratinocytes from c-jun(Deltaep) mice proliferate poorly, show increased differentiation, and form prominent cortical actin bundles, most likely because of decreased expression of EGFR and its ligand HB-EGF. In the absence of c-Jun, tumor-prone K5-SOS-F transgenic mice develop smaller papillomas, with reduced expression of EGFR in basal keratinocytes. Thus, using three experimental systems, we show that EGFR and HB-EGF are regulated by c-Jun, which controls eyelid development, keratinocyte proliferation, and skin tumor formation.

Impaired postnatal hepatocyte proliferation and liver regeneration in mice lacking c-jun in the liver

Mice lacking the AP‐1 transcription factor c‐jun die at mid‐gestation showing heart defects and impaired hepatogenesis. To inactivate c‐jun in hepatocytes, mice carrying a floxed c‐jun allele were generated. Perinatal liver‐specific c‐jun deletion caused reduced hepatocyte proliferation and decreased body size. After partial hepatectomy, half of the mutants died and liver regeneration was impaired. This phenotype was not present in mice lacking the N‐terminal phosphorylation sites of c‐Jun. The failure to regenerate was accompanied by increased cell death and lipid accumulation in hepatocytes. Moreover, cyclin‐dependent kinases and several cell cycle regulators were affected, resulting in inefficient G1–S phase progression. These studies identify c‐Jun as a critical regulator of hepatocyte proliferation and survival during liver development and regeneration.

Mice humanised for the EGF receptor display hypomorphic phenotypes in skin, bone and heart

Mice lacking the epidermal growth factor receptor (EGFR) develop epithelial defects and a neurodegenerative disease and die within the first month of birth. By employing a conditional knock-in approach using the human EGFR cDNA mice humanised for EGFR (hEGFRKI/KI) were generated. Homozygous hEGFRKI/KI mice are viable and live up to six months. However, these mice are growth retarded and show skin and hair defects similar to Egfr-/- mutants. Interestingly, the neurodegeneration is fully rescued in hEGFRKI/KI mice, however, they develop a severe heart hypertrophy with semilunar valve abnormalities. Moreover, hEGFRKI/KI mice display accelerated chondrocyte and osteoblast differentiation, a phenotype that is also present in Egfr-/- mice and has not been previously described. The severity of the phenotypes correlates with the expression levels of the hEGFRKI allele, which is not efficiently expressed in epithelial and bone cells, but is expressed at similar and even higher levels as the endogenous Egfr in brain and heart. These results demonstrate that mice humanised for EGFR display tissue-specific hypomorphic phenotypes and describe a novel function for EGFR in bone development.

Guidelines for vaccination of immunocompromised individuals

Immunosuppression of various origins is associated with an increased risk of infection; therefore the prevention of infectious diseases by vaccination is especially important in immunocompromised patients. However, the response to vaccinations is often reduced in these risk groups and the application of live vaccines is contraindicated during immunosuppression.In the following expert statement, recommendations for vaccination were created on the basis of current evidence and theoretical/immunological considerations. Axa0first, general part elaborates on efficacy and safety of vaccinations during immunosuppression, modes of action of immunosuppressive medications and recommended time intervals between immunosuppressive treatments and vaccinations. Axa0core piece of this part is axa0graduation of immunosuppression into three stages, i.u2009e. no relevant immunosuppression, mild to moderate and severe immunosuppression and the assignment of various medications (including biologicals) to one of those stages; this is followed by an overview of possible and necessary vaccinations in each of those stages.The second part gives detailed vaccination guidelines for common diseases and therapies associated with immunosuppression. Primary immune deficiencies, chronic kidney disease, diabetes mellitus, solid and hematological tumors, hematopoetic stem cell transplantation, transplantation of solid organs, aspenia, rheumatological-, gastroenterologic-, dermatologic-, neurologic diseases, biologicals during pregnancy and HIV infection are dealt with.These vaccination guidelines, compiled for the first time in Austria, aim to be of practical help for physicians to facilitate and improve vaccination coverage in immunocompromised patients and their household members and contact persons.ZusammenfassungImmunsuppression unterschiedlicher Genese ist mit einem erhöhten Infektionsrisiko verbunden; daher ist die Prävention von impfpräventablen Erkrankungen bei den betroffenen Personengruppen besonders wichtig. Allerdings ist das Angehen von Impfungen oftmals reduziert bzw. die Applikation von Lebendimpfungen während Immunsuppression kontraindiziert.Im folgenden Expertenstatement wurden Empfehlungen zur Impfversorgung auf der Basis bestehender Evidenz und auf theoretischen/immunologischen Überlegungen erarbeitet. Ein erster, allgemeiner Teil geht auf Wirksamkeit und Sicherheit von Impfungen bei Immunsuppression, Wirkmechanismen immunsuppressiver Medikamente und empfohlene Zeitabstände zwischen immunsuppressiven Behandlungen und Impfungen ein. Ein Kernstück dieses Teils ist die Graduierung der Immunsuppression in drei Stadien, i.u2009e. keine relevante, leichte bis mittelgradige und schwere Immunsuppression und die Zuordnung von diversen Medikamenten (einschließlich Biologika) zu einem dieser drei Immunsuppressionsgrade, gefolgt von einer Übersicht der im jeweiligen Stadium möglichen und nötigen Impfungen.Im zweiten speziellen Teil werden detaillierte Impfempfehlungen bei häufigen immunsuppressiven Erkrankungen bzw. unter immunsuppressiven Therapien behandelt. Dabei wurden auf angeborene Immundefekte, chronische Nierenerkrankungen, Diabetes mellitus, solide Tumoren und hämatologische Malignome, hämatopoietische Stammzelltransplantation, Transplantation solider Organe, Asplenie, rheumatologische-, gastroenterologische-, dermatologische, neurologische Erkrankungen, Biologika in der Schwangerschaft und HIV-Infektion eingegangen. Diese in Österreich erstmals zusammengefassten Impfempfehlungen sollen in der Praxis zu einer erleichterten und verbesserten Impfversorgung dieser Patientengruppen und deren Kontaktpersonen beitragen.SummaryImmunosuppression of various origins is associated with an increased risk of infection; therefore the prevention of infectious diseases by vaccination is especially important in immunocompromised patients. However, the response to vaccinations is often reduced in these risk groups and the application of live vaccines is contraindicated during immunosuppression.In the following expert statement, recommendations for vaccination were created on the basis of current evidence and theoretical/immunological considerations. Axa0first, general part elaborates on efficacy and safety of vaccinations during immunosuppression, modes of action of immunosuppressive medications and recommended time intervals between immunosuppressive treatments and vaccinations. Axa0core piece of this part is axa0graduation of immunosuppression into three stages, i.u2009e. no relevant immunosuppression, mild to moderate and severe immunosuppression and the assignment of various medications (including biologicals) to one of those stages; this is followed by an overview of possible and necessary vaccinations in each of those stages.The second part gives detailed vaccination guidelines for common diseases and therapies associated with immunosuppression. Primary immune deficiencies, chronic kidney disease, diabetes mellitus, solid and hematological tumors, hematopoetic stem cell transplantation, transplantation of solid organs, aspenia, rheumatological-, gastroenterologic-, dermatologic-, neurologic diseases, biologicals during pregnancy and HIV infection are dealt with.These vaccination guidelines, compiled for the first time in Austria, aim to be of practical help for physicians to facilitate and improve vaccination coverage in immunocompromised patients and their household members and contact persons.

Impfungen bei Immundefekten/Immunsuppression – Expertenstatement und Empfehlungen

Immunosuppression of various origins is associated with an increased risk of infection; therefore the prevention of infectious diseases by vaccination is especially important in immunocompromised patients. However, the response to vaccinations is often reduced in these risk groups and the application of live vaccines is contraindicated during immunosuppression.In the following expert statement, recommendations for vaccination were created on the basis of current evidence and theoretical/immunological considerations. Axa0first, general part elaborates on efficacy and safety of vaccinations during immunosuppression, modes of action of immunosuppressive medications and recommended time intervals between immunosuppressive treatments and vaccinations. Axa0core piece of this part is axa0graduation of immunosuppression into three stages, i.u2009e. no relevant immunosuppression, mild to moderate and severe immunosuppression and the assignment of various medications (including biologicals) to one of those stages; this is followed by an overview of possible and necessary vaccinations in each of those stages.The second part gives detailed vaccination guidelines for common diseases and therapies associated with immunosuppression. Primary immune deficiencies, chronic kidney disease, diabetes mellitus, solid and hematological tumors, hematopoetic stem cell transplantation, transplantation of solid organs, aspenia, rheumatological-, gastroenterologic-, dermatologic-, neurologic diseases, biologicals during pregnancy and HIV infection are dealt with.These vaccination guidelines, compiled for the first time in Austria, aim to be of practical help for physicians to facilitate and improve vaccination coverage in immunocompromised patients and their household members and contact persons.ZusammenfassungImmunsuppression unterschiedlicher Genese ist mit einem erhöhten Infektionsrisiko verbunden; daher ist die Prävention von impfpräventablen Erkrankungen bei den betroffenen Personengruppen besonders wichtig. Allerdings ist das Angehen von Impfungen oftmals reduziert bzw. die Applikation von Lebendimpfungen während Immunsuppression kontraindiziert.Im folgenden Expertenstatement wurden Empfehlungen zur Impfversorgung auf der Basis bestehender Evidenz und auf theoretischen/immunologischen Überlegungen erarbeitet. Ein erster, allgemeiner Teil geht auf Wirksamkeit und Sicherheit von Impfungen bei Immunsuppression, Wirkmechanismen immunsuppressiver Medikamente und empfohlene Zeitabstände zwischen immunsuppressiven Behandlungen und Impfungen ein. Ein Kernstück dieses Teils ist die Graduierung der Immunsuppression in drei Stadien, i.u2009e. keine relevante, leichte bis mittelgradige und schwere Immunsuppression und die Zuordnung von diversen Medikamenten (einschließlich Biologika) zu einem dieser drei Immunsuppressionsgrade, gefolgt von einer Übersicht der im jeweiligen Stadium möglichen und nötigen Impfungen.Im zweiten speziellen Teil werden detaillierte Impfempfehlungen bei häufigen immunsuppressiven Erkrankungen bzw. unter immunsuppressiven Therapien behandelt. Dabei wurden auf angeborene Immundefekte, chronische Nierenerkrankungen, Diabetes mellitus, solide Tumoren und hämatologische Malignome, hämatopoietische Stammzelltransplantation, Transplantation solider Organe, Asplenie, rheumatologische-, gastroenterologische-, dermatologische, neurologische Erkrankungen, Biologika in der Schwangerschaft und HIV-Infektion eingegangen. Diese in Österreich erstmals zusammengefassten Impfempfehlungen sollen in der Praxis zu einer erleichterten und verbesserten Impfversorgung dieser Patientengruppen und deren Kontaktpersonen beitragen.SummaryImmunosuppression of various origins is associated with an increased risk of infection; therefore the prevention of infectious diseases by vaccination is especially important in immunocompromised patients. However, the response to vaccinations is often reduced in these risk groups and the application of live vaccines is contraindicated during immunosuppression.In the following expert statement, recommendations for vaccination were created on the basis of current evidence and theoretical/immunological considerations. Axa0first, general part elaborates on efficacy and safety of vaccinations during immunosuppression, modes of action of immunosuppressive medications and recommended time intervals between immunosuppressive treatments and vaccinations. Axa0core piece of this part is axa0graduation of immunosuppression into three stages, i.u2009e. no relevant immunosuppression, mild to moderate and severe immunosuppression and the assignment of various medications (including biologicals) to one of those stages; this is followed by an overview of possible and necessary vaccinations in each of those stages.The second part gives detailed vaccination guidelines for common diseases and therapies associated with immunosuppression. Primary immune deficiencies, chronic kidney disease, diabetes mellitus, solid and hematological tumors, hematopoetic stem cell transplantation, transplantation of solid organs, aspenia, rheumatological-, gastroenterologic-, dermatologic-, neurologic diseases, biologicals during pregnancy and HIV infection are dealt with.These vaccination guidelines, compiled for the first time in Austria, aim to be of practical help for physicians to facilitate and improve vaccination coverage in immunocompromised patients and their household members and contact persons.