Home Institution
Charité Universitätsmedizin Berlin

Host Institution(s)
Maine Medical Center Research Institute (MMCRI)Center for Molecular Medicine, Scarborough, ME
Mentor: Volkhard Lindner, M.D., Ph.D.

E-Mail: tahir_d@yahoo.de

Nevertheless, I felt here often more welcome than back in Germany sometimes from the very first moment when I arrived in Maine. While people in Germany consider the Americans as superficial, I disagree with this judgement now and would assess it differently. For example, I experienced the so called “superficiality” as very nice and helpful for integrating people from abroad. Namely, as a German of Turkish origin, I felt myself for the first time in my life considered as a REAL German. In contrast to most of the Eastern societies, it is more difficult to get American friends. But after a while you gain friends just like in Germany. I think most of the Americans, in Maine especially, are liberal minded, self-critical, and friendly.

I met here a lot of people from all over the world. I feel that I have gained close friendships with people from various parts of this world, which is just the best thing you can get from a stay like this.

My mentor and all of the people here in the institute were very helpful in organising my life here. Of course, problems like not to having a car in the first month here in Scarborough, ME, where you just do not have any public transportation, did not make life really easy going. But I would not want to have missed any of that time, because I got to know the people to whom I will be grateful forever. I consider it as a period of growing for myself.

I had in my lab, in this very well equipped small institute, the best opportunities to learn a lot of scientific methods. In my group I could not just work on my own projects, but I could also contribute and work with my colleagues as a real team on the whole ongoing research here. Hence, the limiting factor of learning more would not be to have fewer topics, but rather to not have enough time.

• If you come to Maine then come with savings, and try to get a non-American car. Probably you won't even be able to go to the grocery store without a car here. There are some internet groceries which deliver great Turkish food stuff. They have also sometimes special offers. See e.g. at www.yiyelim.com or www.eniyibakkal.com.
• If you are like me, not from the coast in Germany, then enjoy the fish and all the seafood here. You will get everywhere very good seafood for affordable prices!
• You will find special offers for everything. Just keep your eyes open. Then you will experience that life in Maine is not as expensive as it is usually.

Winter in Maine

We recently identified collagen triple helix repeat containing-1 (Cthrc1) as a novel gene induced in adventitial fibroblasts after arterial injury. Cthrc1 is a 30kDa secreted protein that has the ability to inhibit collagen matrix synthesis. Cthrc1 is also glycosylated and retains a signal sequence consistent with the presence of Cthrc1 in the extracellular space. In injured arteries and skin wounds we have found Cthrc1 expression to be associated with myofibroblasts and sites of collagen matrix deposition. Furthermore, we demonstrated that Cthrc1 inhibits collagen matrix deposition in vitro. Using in situ hybridization and immunohistochemistry we characterized the expression domains of Cthrc1 during murine embryonic development and in postnatal tissues. In mouse embryos, Cthrc1 was expressed in the visceral endoderm, notochord, neural tube, developing kidney, and heart. Abundant expression of Cthrc1 was observed in the developing skeleton, i.e. in cartilage primordia, in growth plate cartilage with exclusion of the hypertrophic zone, in the bone matrix and periostium. Bones from adults showed expression of Cthrc1 only in the bone matrix and periostium while the articular cartilage lacked expression. Cthrc1 is typically expressed at epithelial-mesenchymal interfaces that include the epidermis and dermis, basal corneal epithelium, airway epithelium, esophagus epithelium, choroid plexus epithelium, and meninges. In the adult kidney, collecting ducts and distal tubuli expressed Cthrc1. Collectively, the sites of Cthrc1 expression overlap considerably with those reported for TGF- family members and interstitial collagens. The present study provides useful information towards the understanding of potential Cthrc1 functions.

Effects of Cthrc1 overexpression on carbon tetrachloride-induced liver fibrosis

Background:
Collagen triple helix repeat containing-1 is a novel protein identified in our lab. Cthrc-1 is preferentially expressed in areas of epithelial-mesenchymal interfaces during embryogenesis as well as in the adult. Cthrc-1 is able to inhibit collagen expression and promote cell migration in vitro.
Fibrosis is characterized by excessive accumulation of collagen fibers in tissues. Organ fibrosis develops frequently in response to noxious and toxic injuries. Clinically of major significance is the alcohol-induced liver cirrhosis and cirrhosis of the liver caused by chronic viral infection. Therefore, understanding the mechanisms of fibrosis and its contributing factors are of major importance.
TGFß is known to promote collagen deposition. Mice overexpressing Cthrc-1 at high levels die during embryonic development or perinatally as a consequence of reduced collagen type I deposition in bone resulting in brittle bones and other defects of the skeletal system. In our transgenic Tg15 line Cthrc-1 is under the control of the CMV promoter. Cthrc-1 is not expressed in the liver of wildtype mice whereas expression of Cthrc1 is observed in the Cthrc1 transgenic Tg15 line. Carbon tetrachloride (CCl4) is well described as a liver toxin and it is widely used to induct liver fibrosis and cirrhosis in rodents.

Purpose:
The purpose of this study is to establish a liver fibrosis model for the strain used in our lab and investigate whether the development of liver fibrosis is altered in the presence of increased Cthrc1 levels compared to wildtype mice. Furthermore, we sought to evaluate the role of the TGF-ß signalling pathway in fibrosing liver tissue from Cthrc1 transgenic and wild-type mice.

Materials and Methods:
CMV promoter driven Cthrc-1 transgenic mice in the FVB background were generated in our laboratory. Carbon tetrachloride diluted in olive oil was injected i.p. every 3 or 5 days for a total period of up to 8 week. Animals were euthanized 3 days after the last injection and livers were collected for histology, immunohistochemistry, RNA preparation and immunoblotting. Genotyping was performed by PCR. Different experimental groups were gender and age matched. Cthrc1 expression levels were determined in lysates from liver tissue by western blotting. Collagen was identified on sectioned liver tissue with Picro Sirius Red staining and the degree of fibrosis was staged in a standardized manner: F0=no fibrosis, F1=mild fibrosis, F2=severe fibrosis, F3=liver cirrhosis. 4% paraformaldehyde-fixed sections were used to determine the amount of collagen with the FCF-Green/Sirius Red spectrophotometrically. RNA expression and protein levels of TGF-ß pathway members as well as Cthrc-1 will be assessed using RT-PCR, Northern blotting and Western blotting.

Result/Conclusion:
in progress