Functional role of laminin α1 chain during cerebellum development

We had developed a conditional Laminin α 1 knockout-mouse model (Lama1(cko)) bypassing embryonic lethality of Lama1 deficient mice to study the role of this crucial laminin chain during late developmental phases and organogenesis. Here, we report a strong defect in the organization of the adult cerebellum of Lama1(cko) mice. Our study of the postnatal cerebellum of Lama1(cko) animals revealed a disrupted basement membrane correlated to an unexpected excessive proliferation of granule cell precursors in the external granular layer (EGL). This was counteracted by a massive cell death occurring between the postnatal day 7 (P7) and day 20 (P20) resulting in a net balance of less cells and a smaller cerebellum. Our data show that the absence of Lama1 has an impact on the Bergmann glia scaffold that aberrantly develops. This phenotype is presumably responsible for the observed misplacing of granule cells that may explain the overall perturbation of the layering of the cerebellum and an aberrant folia formation.

Roles of the translationally controlled tumour protein (TCTP) and the double-stranded RNA-dependent protein kinase, PKR, in cellular stress responses

Translationally controlled tumour protein (TCTP) is a highly conserved protein present in all eukaryotic organisms. Various cellular functions and molecular interactions have been ascribed to this protein, many related to its growth-promoting and antiapoptotic properties. TCTP levels are highly regulated in response to various cellular stimuli and stresses. We have shown recently that the double-stranded RNA-dependent protein kinase, PKR, is involved in translational regulation of TCTP. Here we extend these studies by demonstrating that TCTP is downregulated in response to various proapoptotic treatments, in particular agents that induce Ca(++) stress, in a PKR-dependent manner. This regulation requires phosphorylation of protein synthesis factor eIF2alpha. Since TCTP has been characterized as an antiapoptotic and Ca(++)-binding protein, we asked whether it is involved in protecting cells from Ca(++)-stress-induced apoptosis. Overexpression of TCTP partially protects cells against thapsigargin-induced apoptosis, as measured using caspase-3 activation assays, a nuclear fragmentation assay, using fluorescence-activated cell sorting analysis, and time-lapse video microscopy. TCTP also protects cells against the proapoptotic effects of tunicamycin and etoposide, but not against those of arsenite. Our results imply that cellular TCTP levels influence sensitivity to apoptosis and that PKR may exert its proapoptotic effects at least in part through downregulation of TCTP via eIF2alpha phosphorylation.

A report on 222 cases of oral squamous cell carcinoma

Cancer is the second leading cause of death in the United States after cardiovascular diseases. Cancer of the oral cavity and pharynx accounts for approximately 2.5% of all cancer cases. This study attempts to highlight some of the risk factors and the clinical signs associated with oral cancer. Data over a 13-year period were collected from the Case Western Reserve University Oral Pathology Laboratory. There were 222 cases of squamous cell carcinoma. The results indicated that the typical male patient was 7 years younger than the typical female patient. Apart from the use of alcohol and tobacco, the wearing of removable prostheses was associated with an increased rate of malignancy. The risks of malignancy were associated with the site and color of the lesions. In addition, we found that the suspicion of cancer among clinicians tend to be higher when the lesions were larger, ulcerated, painful, and hemorrhagic.