Biology subjects

Halwachs, B.

Publications and source records attributed to Halwachs, B..

4 recordsLinked to original sources

bioRxiv2024

A non-catalytic function of a disintegrin and metalloprotease 10 determines hepatic progenitor cell fate

During chronic liver disease, hepatocytes may undergo proliferative arrest, leading to the activation, expansion and differentiation of hepatic progenitor cells (HPCs). Here we observe that expression of A Disintegrin And Metalloprotease (ADAM) 10 is increased in human and murine chronic liver disease correlating with HPC expansion. We report that proteolytic processing of ADAM10 by ADAM9 and generation of an ADAM10 intracellular domain that translocates to the nucleus, rather than ADAM10 enzymatic activity is essential for the regulation of HPC gene expression and differentiation. Genetic loss of ADAM10 in vitro and in vivo enhances stemness gene expression, increases the accumulation of undifferentiated HPCs and promotes the formation of liver fibrosis. Taken together, we demonstrate that a non-catalytic function of ADAM10 is an essential regulator of HPC fate and HPC-driven regeneration. Our data ascribe a non-proteolytic function to ADAM proteases which may be a general concept in adult tissue stem cells.

cell biology↗

bioRxiv2024

ADAM17 regulates hepatic DNA damage repair and tumour formation

BackgroundHepatocellular carcinoma (HCC) is one of the leading causes of cancer deaths worldwide. Still, therapy options for this tumour entity are limited and novel therapeutic options are highly sought after. Genomic instability of hepatocytes promotes oncogenic transformation and underlies the regulation of micro-environmental signalling cues. The membrane-bound a disintegrin and metalloprotease (ADAM) 17 is a major regulator of micro-environmental signals through the proteolytic release of paracrine factors. However, its role in hepatic DNA damage repair and its contribution to hepatic tumourigenesis is still unclear. MethodsWe investigated the effect of ADAM17 on diethylnitrosamine (DEN)-induced acute DNA damage and subsequent DNA damage repair by utilizing mice with ubiquitous or myeloid-specific genetic deficiency in ADAM17. DNA double strand breaks and inflammation were investigated by immunofluorescence of liver tissue sections. tumourigenesis in mice with myeloid-specific ADAM17-deficiency was investigated in a chemically induced hepatocarcinogenesis model. ResultsADAM17 on myeloid cells, in particular Kupffer cells is essentially involved in the non-cell autonomous regulation of DNA damage repair in hepatocytes. Parenchymal ADAM17 regulates hepatocyte fate and recruitment of infiltrating myeloid cells. Furthermore, myeloid ADAM17 promotes hepatic tumour initiation and correlates with poor prognosis in human HCC. ConclusionsWe identified ADAM17, in particular on myeloid cells as an essential driver of hepatic tumourigenesis and as a potential novel drug target for the treatment of hepatic malignancies.

cancer biology↗

bioRxiv2023

Modulation of human kinase activity through direct interaction with SARS-CoV-2 proteins

The dysregulation of cellular signaling upon SARS-CoV-2 infection is mediated via direct protein interactions, with the human protein kinases constituting the major impact nodes in the signaling networks. Here, we employed a targeted yeast two-hybrid matrix approach to identify direct SARS-CoV-2 protein interactions with an extensive set of human kinases. We discovered 51 interactions involving 14 SARS-CoV-2 proteins and 29 human kinases, including many of the CAMK and CMGC kinase family members, as well as non-receptor tyrosine kinases. By integrating the interactions identified in our screen with transcriptomics and phospho-proteomics data, we revealed connections between SARS-CoV-2 protein interactions, kinase activity changes, and the cellular phospho-response to infection and identified altered activity patterns in infected cells for AURKB, CDK2, CDK4, CDK7, ABL2, PIM2, PLK1, NEK2, TRIB3, RIPK2, MAPK13, and MAPK14. Finally, we demonstrated direct inhibition of the FER human tyrosine kinase by the SARS-CoV-2 auxiliary protein ORF6, hinting at pressures underlying ORF6 changes observed in recent SARS-CoV-2 strains. Our study expands the SARS-CoV-2 - host interaction knowledge, illuminating the critical role of dysregulated kinase signaling during SARS-CoV-2 infection.

biochemistry↗

bioRxiv2023

Mutational scanning pinpoints distinct binding sites of key ATGL regulators in lipolysis

ATGL is the key enzyme in intracellular lipolysis playing a critical role in metabolic and cardiovascular diseases. ATGL is tightly regulated through a known set of protein-protein interaction partners with activating or inhibiting functions in control of lipolysis. However, the binding mode and protein interaction sites of ATGL and its partners are unknown. Using deep mutational protein interaction perturbation scanning we generated comprehensive profiles of single amino acid variants effecting the interactions of ATGL with its regulatory partners: CGI-58, G0S2, PLIN1, PLIN5 and CIDEC. Twenty-three ATGL variants gave a specific interaction perturbation pattern when validated in co-immunoprecipitation experiments in mammalian cells. We identified and characterized eleven, highly selective ATGL "switch" mutations which affect the interaction of one of the five partners without affecting the others. Switch mutations thus provided distinct interaction determinants for ATGLs key regulatory proteins at an amino acid resolution. When tested for triglyceride hydrolase activity in vitro and lipolysis in cells, the activity patterns of the ATGL switch variants traced to their protein interaction profile. In the context of structural data, the integration of variant binding and activity profiles provided important insights into lipolysis regulation and the impact of mutations in human disease.

systems biology↗