Janna Hachmann

The article gives an overview of the research waste problem, which describes research activities that do not aid in the discovery of new findings or knowledge and therefore do not add societal benefit. The responsible parties, main causes and suggested solutions are presented.

(Article in German)

The human paracaspase MALT1 is a caspase homolog that plays a central role in NF-κB signaling. Over the past few years it has become clear that this is due to a combination of its scaffolding and proteolytic function. Knockout mice and mice expressing a catalytically dead variant of the protease have provided valuable information. This review aims to provide an overview of recent developments regarding the enzymatic mechanism and specificity of MALT1, its substrates discovered to date… Mehr anzeigen

The human paracaspase MALT1 is a caspase homolog that plays a central role in NF-κB signaling. Over the past few years it has become clear that this is due to a combination of its scaffolding and proteolytic function. Knockout mice and mice expressing a catalytically dead variant of the protease have provided valuable information. This review aims to provide an overview of recent developments regarding the enzymatic mechanism and specificity of MALT1, its substrates discovered to date, different mouse models, as well as the role of MALT1 in NF-κB signaling downstream of a variety of different receptors. Weniger anzeigen

The human paracaspase mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) plays a central role in nuclear factor-kappaB (NF-kappaB) signaling as both a protease and scaffolding protein. Knocking out MALT1 leads to impaired NF-kappaB signaling and failure to mount an effective immune response. However, it is unclear to which degree it is the scaffolding function versus the proteolytic activity of MALT1 that is essential. Previous work involving a MALT1 inhibitor with low… Mehr anzeigen

The human paracaspase mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) plays a central role in nuclear factor-kappaB (NF-kappaB) signaling as both a protease and scaffolding protein. Knocking out MALT1 leads to impaired NF-kappaB signaling and failure to mount an effective immune response. However, it is unclear to which degree it is the scaffolding function versus the proteolytic activity of MALT1 that is essential. Previous work involving a MALT1 inhibitor with low selectivity suggests that the enzymatic function plays an important role in different cell lines. To help elucidate this proteolytic role of MALT1, we have designed activity-based probes that inhibit its proteolytic activity. The probes selectively label active enzyme and can be used to inhibit MALT1 and trace its activity profile, helping to create a better picture of the significance of the proteolytic function of MALT1. Weniger anzeigen

The paracaspase domain of MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) is a component of a gene translocation fused to the N-terminal domains of the cellular inhibitor of apoptosis protein 2. The paracaspase itself, commonly known as MALT1, participates in the NF-κB (nuclear factor κB) pathway, probably by driving survival signals downstream of the B-cell antigen receptor through MALT1 proteolytic activity. We have developed methods for the expression and… Mehr anzeigen

The paracaspase domain of MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) is a component of a gene translocation fused to the N-terminal domains of the cellular inhibitor of apoptosis protein 2. The paracaspase itself, commonly known as MALT1, participates in the NF-κB (nuclear factor κB) pathway, probably by driving survival signals downstream of the B-cell antigen receptor through MALT1 proteolytic activity. We have developed methods for the expression and purification of recombinant full-length MALT1 and its constituent catalytic domain alone. Both are activated by dimerization without cleavage, with a similar dimerization barrier to the distantly related cousins, the apical caspases. By using positional-scanning peptidyl substrate libraries we demonstrate that the activity and specificity of full-length MALT1 is recapitulated by the catalytic domain alone, showing a stringent requirement for cleaving after arginine, and with striking peptide length constraints for efficient hydrolysis. Rates of cleavage (kcat/Km values) of optimal peptidyl substrates are in the same order as for a putative target protein CYLD. Thus MALT1 has many similarities to caspase 8, even cleaving the putative target protein CYLD with comparable efficiencies, but with diametrically opposite primary substrate specificity. Weniger anzeigen

Advanced metastatic disease is difficult to manage and specific therapeutic targets are rare. We showed earlier that metastatic breast cancer cells use the activated conformer of adhesion receptor integrin alphavbeta3 for dissemination. We now investigated if targeting this form of the receptor can impact advanced metastatic disease, and we analyzed the mechanisms involved. Treatment of advanced multi-organ metastasis in SCID mice with patient-derived scFv antibodies specific for activated… Mehr anzeigen

Advanced metastatic disease is difficult to manage and specific therapeutic targets are rare. We showed earlier that metastatic breast cancer cells use the activated conformer of adhesion receptor integrin alphavbeta3 for dissemination. We now investigated if targeting this form of the receptor can impact advanced metastatic disease, and we analyzed the mechanisms involved. Treatment of advanced multi-organ metastasis in SCID mice with patient-derived scFv antibodies specific for activated integrin alphavbeta3 caused stagnation and regression of metastatic growth. The antibodies specifically localized to tumor lesions in vivo and inhibited alphavbeta3 ligand binding at nanomolar levels in vitro. At the cellular level, the scFs associated rapidly with high affinity alphavbeta3 and dissociated extremely slowly. Thus, the scFvs occupy the receptor on metastatic tumor cells for prolonged periods of time, allowing for inhibition of established cell interaction with natural alphavbeta3 ligands. Potential apoptosis inducing effects of the antibodies through interaction with caspase-3 were studied as potential additional mechanism of treatment response. However, in contrast to a previous concept, neither the RGD-containing ligand mimetic scFvs nor RGD peptides bound or activated caspase-3 at the cellular or molecular level. This indicates that the treatment effects seen in the animal model are primarily due to antibody interference with alphavbeta3 ligation. Inhibition of advanced metastatic disease by treatment with cancer patient derived single chain antibodies against the activated conformer of integrin alphavbeta3 identifies this form of the receptor as a suitable target for therapy. Weniger anzeigen