Supplementary nuclear receptor NHR-60 is required for normal embryonic and early larval development of Caenorhabditis elegans.

The C. elegans genome encodes an unexpectedly large number of NHRs, the majority of which are classified as supplementary nuclear receptors (supnrs) that are likely to have evolved from an ancestral protein related to vertebrate HNF-4. To understand the need for this large repertoire of potential ligand-activated transcription factors, we have begun to study an 18-member subgroup defined by DNA binding domain relatedness. Here we report on NHR-60, a supnr expressed ubiquitously throughout development with a distinct pattern of localization on the nuclear periphery. Both antibody staining and GFP reporter genes demonstrated high-level expression and accumulation of NHR-60 in seam cell nuclei that is dependent on NHR-23 activity. Interference with NHR-60 activity, by either RNAi or overexpression of a putative dominant negative isoform, results in embryonic and early larval lethality, including defects in seam cell development. This adds NHR-60 to the list of C. elegans NHRs playing important roles in development.

The IA-2 gene family: homologs in Caenorhabditis elegans, Drosophila and zebrafish.

AIMS/HYPOTHESIS: IA-2 and IA-2beta are major autoantigens in Type I (insulin-dependent) diabetes mellitus and are expressed in neuroendocrine tissues including the brain and pancreatic islets of Langerhans. Based on sequence analysis, IA-2 and IA-2beta are transmembrane protein tyrosine phosphatases but lack phosphatase activity because of critical amino acid substitutions in the catalytic domain. We studied the evolutionary conservation of IA-2 and IA-2beta genes and searched for homologs in non-mammalian vertebrates and invertebrates. METHODS: IA-2 from various species was identified from EST sequences or cloned from cDNA libraries or both. Expression in tissues was determined by transfection and in situ hybridization. RESULTS: We identified homologs of IA-2 in C. elegans, Drosophila, and zebrafish which showed 46, 58 and 82 % identity and 60, 65 and 87 % similarity, respectively, to the amino acids of the intracellular domain of human IA-2. Further studies showed that IA-2 was expressed in the neural tissues of the three species. Comparison of the genomic structure of the intracellular domain of human IA-2 with that of human IA-2beta showed that they were nearly identical and comparison of the intron-exon boundaries of Drosophila IA-2 with human IA-2 and IA-2beta showed a high degree of relatedness. CONCLUSION/INTERPRETATION: Based on these findings and sequence analysis of IA-2 homologs in mammals, we conclude that there is an IA-2 gene family which is a part of the larger protein tyrosine phosphatase superfamily. The IA-2 and IA-2beta genes represent two distinct subgroups within the IA-2 family which originated over 500 million years ago, long before the development of the pancreatic islets of Langerhans.

Regulation of postembryonic G(1) cell cycle progression in Caenorhabditis elegans by a cyclin D/CDK-like complex.

In many organisms, initiation and progression through the G(1) phase of the cell cycle requires the activity of G(1)-specific cyclins (cyclin D and cyclin E) and their associated cyclin-dependent kinases (CDK2, CDK4, CDK6). We show here that the Caenorhabditis elegans genes cyd-1 and cdk-4, encoding proteins similar to cyclin D and its cognate cyclin-dependent kinases, respectively, are necessary for proper division of postembryonic blast cells. Animals deficient for cyd-1 and/or cdk-4 activity have behavioral and developmental defects that result from the inability of the postembryonic blast cells to escape G(1) cell cycle arrest. Moreover, ectopic expression of cyd-1 and cdk-4 in transgenic animals is sufficient to activate a S-phase reporter gene. We observe no embryonic defects associated with depletion of either of these two gene products, suggesting that their essential functions are restricted to postembryonic development. We propose that the cyd-1 and cdk-4 gene products are an integral part of the developmental control of larval cell proliferation through the regulation of G(1) progression.

Comparison of immunosuppressive effects of cyclosporine A in a murine model of systemic candidiasis and of localized thrushlike lesions.

Candida albicans is an opportunistic human pathogen preferentially causing invasive and disseminated infection in patients with defective phagocytic defenses and serious mucocutaneous infection in patients with deficient T-cell function. Phagocytes appear to protect the host from fungal invasion even in the absence of adaptive immune mechanisms, while as-yet-undefined T-cell-dependent factors seem necessary for control of C. albicans on body surfaces. To study host defense mechanisms on body surfaces, we developed a new model of thrush in artificial pneumatized cysts in mice. Cyclosporine A, a relative selective suppressor of T-cell-mediated immunity and natural killer cell activity, promoted the formation of thrushlike lesions on cyst surfaces and impeded elimination of C. albicans from such lesions. As expected from the absence of an impairment of antimicrobial phagocytic activity, cyclosporine A had no effect on systemic candidiasis induced by intravenous inoculation. Surprisingly, athymic nude mice were not more susceptible to superficial candidiasis than control mice and were comparably affected by cyclosporine A. In contrast, beige mice, which in addition to phagocytic dysfunction have reduced natural killer cell activity, were more susceptible to thrushlike lesions, and cyclosporine A was correspondingly less active in this mouse strain. Immunosuppression with cyclosporine A affects host defense mechanisms which are operative against superficial candidiasis but appear superfluous in resistance to the invasive form of this mycosis, an indication for the divergent nature of host defense against the two forms of candidiasis.

Pathologic study of parathyroid glands in tertiary hyperparathyroidism.

Tertiary hyperparathyroidism is defined as persistent parathyroid hyperfunction developing from the secondary hyperplasia that occurs after restoration of renal function by dialysis or kidney transplantation. Controversy continues as to whether parathyroid adenoma or hyperplasia accounts for the autonomous hyperfunction. A review of 128 parathyroids from 41 patients with tertiary hyperparathyroidism revealed marked hyperplasia in 39 patients (95 per cent), with a predominance of chief cells, an abundance of oxyphil cells, and 10- to 40-fold increases in parathyroid mass. This hyperplasia was considered to be the predominant morphologic feature of tertiary hyperparathyroidism. Adenomas, found only in two patients (5 per cent), seem to be rare. Diffuse, moderately enlarged hyperplastic glands were found predominantly in patients with transplants, whereas nodular, markedly enlarged hyperplastic parathyroids were observed more frequently in patients treated by dialysis. In spite of the different patterns of hyperplasia and the different gland sizes in these two groups of patients, the grades of hypercalcemia were similar. The results of ultrastructural studies indicate that the majority of parenchymal cells in diffuse, and some cellular areas in nodular, hyperplasia may consist of cells with high secretory activity that do not respond normally to hypercalcemia. It is concluded that both increased parenchymal mass and cellular differentiation, leading to hyperactivity, account for tertiary hyperparathyroidism.

[Extensive intra-abdominal tumor masses in primary osteomyelofibrosis]. / Ausgedehnte intraabdominale Tumormassen bei primärer Osteomyelofibrose.

A 65-year-old female suffering from agnogenic myeloid metaplasia developed multiple gradually growing tumor masses in the abdomen 4 years after splenectomy. At death, the abdominal cavity was mainly dominated by these masses. At autopsy, histological examination of the tumor tissue revealed extramedullary hematopoiesis with an intensive fibroblastic reaction whose appearance was very similar to the fibrous bone marrow. Pathogenesis, complications and therapy of this unusual manifestation of extramedullary hematopoiesis in agnogenic myeloid metaplasia are discussed.