Biomedical subjects

Karin Schlichting

Publications and source records attributed to Karin Schlichting.

3 recordsLinked to original sources

PubMed2006

Cadherin Cad99C is required for normal microvilli morphology in Drosophila follicle cells.

Microvilli are actin-filled membranous extensions common to epithelial cells. Several proteins have been identified that localize to microvilli. However, most of these proteins are dispensable for the normal morphogenesis of microvilli. Here, we show by immunoelectron microscopy that the non-classical cadherin Cad99C localizes to microvilli of Drosophila ovarian follicle cells. Loss of Cad99C function leads to disorganized and abnormal follicle cell microvilli. Conversely, overexpression of Cad99C in follicle cells results in large bundles of microvilli. Furthermore, altered microvilli morphology correlates with defects in the assembly of the vitelline membrane, an extracellular layer secreted by follicle cells that is part of the eggshell. Finally, we provide evidence that Cad99C is the homolog of vertebrate protocadherin 15. Mutations in the gene encoding protocadherin 15 lead to the disorganization of stereocilia, which are microvilli-derived extensions of cochlear hair cells, and deafness (Usher syndrome type 1F). Our data suggest an essential role for Cad99C in microvilli morphogenesis that is important for follicle cell function. Furthermore, these results indicate that insects and vertebrates use related cadherins to organize microvilli-like cellular extensions.

Animals↗

PubMed2006

Biodegradable composite implants.

Biodegradable implants are established in the field of operative sports medicine. So-called composite implants are increasingly used. The idea to improve biocompatibility and osteoconductivity of biodegradable polymers by modifying them with a ceramic component, has led to the development of these composite implants. Today, an increasing variety of composite implants are available. They have substantially different material characteristics, which depend on matrix polymer choice and the additional ceramic. The material characteristics influence the mechanical properties, in vivo degradation, the osseous replacement and the host-tissue response. It is important to understand their biologic base for a better knowledge of the advantages and risks associated with using composite implants in the field of operative sports medicine. The purpose of this review is to focus on current developments in biodegradable composite implants and their biologic base.

Absorbable Implants↗

PubMed2005

Cadherin Cad99C is regulated by Hedgehog signaling in Drosophila.

The subdivision of the Drosophila wing imaginal disc into anterior and posterior compartments requires a transcriptional response to Hedgehog signaling. However, the genes regulated by Hedgehog signal transduction that mediate the segregation of anterior and posterior cells have not been identified. Here, we molecularly characterize the previously predicted gene cad99C and show that it is regulated by Hedgehog signaling. Cad99C encodes a transmembrane protein with a molecular weight of approximately 184 kDa that contains 11 cadherin repeats in its extracellular domain and a conserved type I PDZ-binding site at its C-terminus. The levels of cad99C RNA and protein are low throughout the wing imaginal disc. However, in the pouch region, these levels are elevated in a strip of anterior cells along the A/P boundary where the Hedgehog signal is transduced. Ectopic expression of Hedgehog, or the Hedgehog-regulated transcription factor Cubitus interruptus, induces high-level expression of Cad99C. Conversely, blocking Hedgehog signal transduction by either inactivating Smoothened or Cubitus interruptus reduces high-level Cad99C expression. Finally, by analyzing mutant clones of cells, we show that Cad99C is not essential for cell segregation at the A/P boundary. We conclude that cad99C is a novel Hedgehog-regulated gene encoding a member of the cadherin superfamily in Drosophila.

Amino Acid Sequence↗