Biomedical subjects

Thomas Reinheckel

Publications and source records attributed to Thomas Reinheckel.

23 records · Page 2Linked to original sources

PubMed2002

Proteasome-dependent turnover of protein disulfide isomerase in oxidatively stressed cells.

Generalized increases in protein oxidation and protein degradation in response to mild oxidative stress have been widely reported, but only a few individual proteins have actually been shown to undergo selective, oxidation-induced proteolysis. Our goal was to find such proteins in Clone 9 liver cells exposed to hydrogen peroxide. Using metabolic radiolabeling of intracellular proteins with [35S]cysteine/methionine, and analysis by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), we found at least three labeled proteins ("A," "B," and "C") whose levels were decreased significantly more than the generalized protein loss after mild oxidative stress. "Protein C" was excised from 2-D PAGE and subjected to N-terminal amino acid microsequencing. "Protein C" was identified as Protein Disulfide Isomerase or PDI (E.C. 5.3.4.1), and this identity was reconfirmed by Western blotting with a C-terminal anti-PDI monoclonal antibody. A combination of quantitative radiometry and Western blotting in 2-D PAGE revealed that PDI was selectively degraded and then new PDI was synthesized, following H2O2 exposure. PDI degradation was blocked by inhibitors of the proteasome, and by cell treatment with proteasome C2 subunit antisense oligonucleotides, indicating that the proteasome was largely responsible for oxidation-induced PDI degradation.

Animals↗

PubMed2002

The lysosomal protease cathepsin L is an important regulator of keratinocyte and melanocyte differentiation during hair follicle morphogenesis and cycling.

We have previously shown that the ubiquitously expressed lysosomal cysteine protease, cathepsin L (CTSL), is essential for skin and hair follicle homeostasis. Here we examine the effect of CTSL deficiency on hair follicle development and cycling in ctsl(-/-) mice by light and electron microscopy, Ki67/terminal dUTP nick-end labeling, and trichohyalin immunofluorescence. Hair follicle morphogenesis in ctsl(-/-) mice was associated with several abnormalities. Defective terminal differentiation of keratinocytes occurred during the formation of the hair canal, resulting in disruption of hair shaft outgrowth. Both proliferation and apoptosis levels in keratinocytes and melanocytes were higher in ctsl(-/-) than in ctsl(+/+) hair follicles. The development of the hair follicle pigmentary unit was disrupted by vacuolation of differentiating melanocytes. Hair cycling was also abnormal in ctsl(-/-) mice. Final stages of hair follicle morphogenesis and the induction of hair follicle cycling were retarded. Thereafter, these follicles exhibited a truncated resting phase (telogen) and a premature entry into the first growth phase. Further abnormalities of telogen development included the defective anchoring of club hairs in the skin, which resulted in their abnormal shedding. Melanocyte vacuolation was again apparent during the hair cycle-associated reconstruction of the hair pigmentary unit. A hallmark of these ctsl(-/-) mice was the severe disruption in the exiting of hair shafts to the skin surface. This was mostly because of a failure of the inner root sheath (keratinocyte layer next to the hair shaft) to fully desquamate. These changes resulted in a massive dilation of the hair canal and the abnormal routing of sebaceous gland products to the skin surface. In summary, this study suggests novel roles for cathepsin proteases in skin, hair, and pigment biology. Principal target tissues that may contain protein substrate(s) for this cysteine protease include the developing hair cone, inner root sheath, anchoring apparatus of the telogen club, and organelles of lysosomal origin (eg, melanosomes).

Animals↗

PubMed2002

Ezrin turnover and cell shape changes catalyzed by proteasome in oxidatively stressed cells.

We find that ezrin, a cytoskeletal protein involved in anchoring actin to the cell membrane, is preferentially degraded and resynthesized after oxidative stress. Ezrin was identified using 2-dimensional gels and amino-terminal microsequencing as one of a select few [35S]methionine prelabeled proteins degraded in clone 9 rat liver cells exposed to hydrogen peroxide (H2O2). Metabolic labeling of cellular proteins with [35S]methionine after oxidative stress showed that resynthesis of ezrin rose dramatically but carboxyl terminus anti-ezrin monoclonal antibodies revealed constant intracellular ezrin levels; in other words, degradation and resynthesis were exactly matched. Ezrin degradation was blocked by selective inhibitors of the proteasome (lactacystin, NLVS, and epoxomycin) and by an antisense oligonucleotide directed against the proteasome C2 subunit. H2O2 also caused major changes in cell shape, including significant increases in cell diameter, which must require substantial cytoskeletal rearrangement. Peroxide-induced increases in cell diameter were, however, blocked by the selective proteasome inhibitor lactacystin. The degradation and resynthesis of ezrin may therefore be an underlying mechanism for overall cell shape changes observed during oxidative stress. Oxidative stress induces extensive protein oxidation and degradation and significant increases in cell blebbing, rounding-up, and overall size. Our results indicate that all these oxidant-induced changes may actually be catalyzed by the proteasome.

Acetylcysteine↗

PubMed2001

Reduced neutrophil sequestration in lung tissue after laparoscopic lavage in a rat peritonitis model.

Laparoscopy to treat abdominal infections is becoming more and more popular. The effects of the CO(2) pneumoperitoneum have not yet been completely clarified. In a rat peritonitis model, therefore, we investigated the influence of laparoscopic lavage in comparison with the conventional technique. A defined multibacterial fecal specimen was installed in the abdominal cavities of 80 rats. These animals were randomized to three groups: group 1 (n = 32), no intervention; group 2 (n = 24), conventional; group 3 (n = 24), laparoscopic lavage. At 1, 2, and 8 hours after the surgical intervention, animals were killed and autopsied. The main outcome measures were bacteremia, interleukin-6 (IL-6) in plasma and ascites, changes in the blood count, and myeloperoxidase (MPO) activity in lung, liver, kidney, and pancreas. Differences of bacteremia were not found. In the ascites a marked increase in IL-6 was observed after 8 hours, which was lower in the treatment groups than in the controls (p <0.025). MPO activity as a measure of the granulocytes present in the tissue showed significant changes only in lung tissue. Two hours after the surgical intervention, the MPO in the lung in the laparoscopy group was significantly lower than that in the controls and the laparotomy group. In conclusion, conventional and laparoscopic lavage reduce inflammation. In this model, laparoscopic lavage with a CO(2) pneumoperitoneum appeared to have no negative influence on the inflammatory reaction during the early postoperative phase. Reduced neutrophil sequestration in lung tissue following laparoscopic lavage reflects the lower level of trauma caused by laparoscopy.

Animals↗

PubMedDate not supplied

An open source protein gel documentation system for proteome analyses.

Data organization and data mining represents one of the main challenges for modern high throughput technologies in pharmaceutical chemistry and medical chemistry. The presented open source documentation and analysis system provides an integrated solution (tutorial, setup protocol, sources, executables) aimed at substituting the traditionally used lab-book. The data management solution provided incorporates detailed information about the processing of the gels and the experimental conditions used and includes basic data analysis facilities which can be easily extended. The sample database and User-Interface are available free of charge under the GNU license from http://webber.physik.uni-freiburg.de/~fallerd/tutorial.htm.

Documentation↗