Search

In dieser Arbeit wurde der Einfluss zyklischer, uniaxialer Dehnung auf die Expression der im Knochenstoffwechsel wichtigen Proteine c-FBJ murine osteosarcoma viral oncogene homolog (c-FOS), Pleiotrophin (PTN) und Midkine (MDK) in Abhängigkeit von Kollagen Typ 1, Poly-L-Lactid (PLLA) bzw. Fibronektin untersucht. Auch die Rolle der beta1-Integrin-abhängigen Interaktion in diesem Prozess wurde näher analysiert. Für die Versuche wurden humane, mesenchymale Stammzellen sowie eine mesenchymale Stammzelllinie mit Telomerase reverser Transkriptase 4 (hMSC-TERT4) verwendet.

Rhabdomyosarcoma is the most common soft tissue sarcoma in children, yet the genetic changes causing this disease are poorly understood. The Fos protein, a major component of the AP-1 transcription factor, is essential for osteoclast differentiation, acts as an oncogene, potentiates transforming signals and controls invasive growth and angiogenesis during tumor progression. To genetically investigate a potential interaction between the p53 and Fos pathways, Trp53/Fos double knock-out mice were generated. These mice develop highly proliferative and invasive rhabdomyosarcomas of the facial and orbital regions with more than 90% penetrance at 6 months of age. Expression of Fos in Trp53/Fos mutant rhabdomyosarcoma cell lines established from primary tumors is associated with enhanced apoptosis and downregulation of Pax7 expression. Our results show that Trp53/Fos double knock-out mice recapitulate major aspects of human rhabdomyosarcoma development and therefore provide a mouse model for the human disease. Furthermore, this study identifies a novel and unexpected tumor suppressive function of the Fos proto-oncogene.

Retinitis pigmentosa (RP) is a hereditary retinal dystrophy which leads to severe visual impairment or blindness and affects about 3.5/1000 of individuals in the industrial world. During the past decades, numerous animal models carrying mutations analogous to mutations in human RP have been studied to elucidate the molecular mechanisms leading to apoptotic photoreceptor cell death in this disease. Up to date, there is no effective treatment to influence the fatal outcome of RP. Recent progress in basic research promotes the development of new therapeutic strategies. In order to restore visual function in blind individuals, the development of electronic photoreceptor prosthesis is being investigated by several researchgroups. Other promising approaches are somatic gene therapy, the application of growth factors and/or pharmacological agents and the inhibition of photoreceptor cell death by interfering with the apoptotic pathway. However, a better understanding of the molecular events leading to cell loss due to photoreceptor apoptosis will be essential for the development of effective treatment.

Lipoprotein abnormalities are a risk factor for atherosclerotic disease and considered to accelerate glomerular injury in kidney disease. Serum levels of Lp(a) are elevated in patients with nephrotic syndrome and Lp(a) deposits are found in diseased glomeruli. Since mesangial hypercellularity is a prominent feature in a variety of glomerular diseases, we studied the effects of Lp(a) on proliferation of cultured rat mesangial cells. DNA synthesis was stimulated in cells incubated in the presence of Lp(a) as were the mRNA levels for c-fos and c-myc, two "early genes" that serve as transcription factors. Lp(a) also accelerated cell growth by 42 +/- 6% compared to control cells. Increased DNA synthesis was partially blunted, when cells were incubated with Lp(a) in the presence of oxygen radical scavengers CAT and SOD. We conclude that Lp(a) abnormalities are likely to contribute to glomerular injury in kidney disease. The mechanism by which Lp(a) alters the proliferation rate of mesangial cells involves the formation of reactive oxygen species.

Newborn hMT-fos-LTR transgenic C3H mice and their non-transgenic siblings were infected with Akv, derived from the ecotropic provirus of the AKR mouse. Bone sarcomas in non-infected transgenics were observed in 20% (3/15) of females at 448 +/- 25 days and in 8% (1/12) of males at 523 days. Akv-infected transgenics developed bone tumors with higher frequency and at younger age: Females in 69% (20/28) at 268 +/- 122 days, males in 83% (24/29) at 279 +/- 109 days. In the majority of the bone tumors of Akv-infected transgenics (70% in females, 59% in males) cellular atypia was lacking and the histological pattern resembled human parosteal osteosarcoma. Only 50% (12/24) of bone tumors in Akv-infected transgenics revealed newly integrated virus sequences by Southern analysis. PCR analysis detected Akv sequences in DNAs of all tumors. Obviously, the insertion of Akv in a few cells induced the considerably accelerated bone tumor growth.