Publications

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18 Publications visible to you, out of a total of 18

Abstract (Expand)

Organ regeneration is a very complex process that includes not only the reconstruction of organ mass but also the reorganisation of homeostatic capabilities. This especially applies for the liver, which performs a variety of metabolic functions. In the last decade, morphogenic pathways such as the Wnt/β-Catenin and Hedgehog signalling pathways have been revealed to orchestrate liver regeneration as well as metabolism. Mathematical models have been successfully applied to liver regeneration, but these have not integrated the Hedgehog signalling pathway. In this review it is tried to compile features of Hh signalling in liver regeneration which can be integrated into liver regeneration modeling.

Author: Madlen Matz-Soja

Date Published: 1st Jul 2017

Publication Type: Not specified

Abstract (Expand)

The Hedgehog signaling pathway is known to be involved in embryogenesis, tissue remodeling, and carcinogenesis. Because of its involvement in carcinogenesis, it seems an interesting target for cancer therapy. Indeed, Sonidegib, an approved inhibitor of the Hedgehog receptor Smoothened (Smo), is highly active against diverse carcinomas, but its use is also reported to be associated with several systemic side effects. Our former work in adult mice demonstrated hepatic Hedgehog signaling to play a key role in the insulin-like growth factor axis and lipid metabolism. The current work using mice with an embryonic and hepatocyte-specific Smo deletion describes an adverse impact of the hepatic Hedgehog pathway on female fertility. In female SAC-KO mice, we detected androgenization characterized by a 3.3-fold increase in testosterone at 12 weeks of age based on an impressive induction of steroidogenic gene expression in hepatocytes, but not in the classic steroidogenic organs (ovary and adrenal gland). Along with the elevated level of testosterone, the female SAC-KO mice showed infertility characterized by juvenile reproductive organs and acyclicity. The endocrine and reproductive alterations resembled polycystic ovarian syndrome and could be confirmed in a second mouse model with conditional deletion of Smo at 8 weeks of age after an extended period of 8 months. We conclude that the down-regulation of hepatic Hedgehog signaling leads to an impaired hormonal balance by the induction of steroidogenesis in the liver. These effects of Hedgehog signaling inhibition should be considered when using Hedgehog inhibitors as anti-cancer drugs.

Authors: Christiane Rennert, Franziska Eplinius, Ute Hofmann, Janina Johänning, Franziska Rolfs, Wolfgang Schmidt-Heck, Reinhardt Guthke, Rolf Gebhardt, Albert M. Ricken, Madlen Matz-Soja

Date Published: 30th May 2017

Publication Type: Not specified

Abstract (Expand)

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in industrialized countries and is increasing in prevalence. The pathomechanisms, however, are poorly understood. This study assessed the unexpected role of the Hedgehog pathway in adult liver lipid metabolism. Using transgenic mice with conditional hepatocyte-specific deletion of Smoothened in adult mice, we showed that hepatocellular inhibition of Hedgehog signaling leads to steatosis by altering the abundance of the transcription factors GLI1 and GLI3. This steatotic 'Gli-code' caused the modulation of a complex network of lipogenic transcription factors and enzymes, including SREBP1 and PNPLA3, as demonstrated by microarray analysis and siRNA experiments and could be confirmed in other steatotic mouse models as well as in steatotic human livers. Conversely, activation of the Hedgehog pathway reversed the "Gli-code" and mitigated hepatic steatosis. Collectively, our results reveal that dysfunctions in the Hedgehog pathway play an important role in hepatic steatosis and beyond.

Authors: M. Matz-Soja, C. Rennert, K. Schonefeld, S. Aleithe, J. Boettger, W. Schmidt-Heck, T. S. Weiss, A. Hovhannisyan, S. Zellmer, N. Kloting, A. Schulz, J. Kratzsch, R. Guthke, R. Gebhardt

Date Published: 17th May 2016

Publication Type: Not specified

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