Commentary
Abstract
In this issue of the JCI, Ciampi et al. report the identification of a novel oncogene in patients affected by radiation-associated thyroid papillary carcinomas. This oncogene derives from a paracentric inversion of the long arm of chromosome 7, which results in an in-frame fusion of the N-terminus of the A-kinase anchor protein 9 (AKAP9) gene with the C-terminal catalytic domain (exons 9–18) of the serine-threonine kinase BRAF. The resulting AKAP9-BRAF fusion protein shows constitutive kinase activity, and it is able to transmit mitogenic signals to the MAPK pathways and to promote malignant transformation of NIH3T3 cells.
Authors
Alfredo Fusco, Giuseppe Viglietto, Massimo Santoro
Abstract
Neurotransplantation as a treatment for Parkinson disease reached the stage of human trials over 15 years ago, but the field, which is still in its infancy, has encountered a number of roadblocks since then, both political and scientific. With hope that stem cells may be used as a new source of dopaminergic neurons to replace the degenerating nerve cells in Parkinson disease looming, it is critical that we learn from the past as we work toward achieving new milestones aimed at making this new therapeutic strategy a reality. One of those milestones, which is an important translational step in the development of stem cell technology and the subject of a report in this issue of the JCI, involves transplanting new dopaminergic cell lines to a primate model of Parkinson disease.
Authors
J. William Langston
Abstract
For several decades, intravenous Ig has been used as treatment for a variety of immune-related diseases, including immune thrombocytopenic purpura (ITP), autoimmune neuropathies, systemic lupus erythematosus, myasthenia gravis, Guillain-Barré syndrome, skin blistering syndromes, and Kawasaki disease. Despite years of use, its mechanism of immunomodulation is still unclear. Recent studies using mouse models of ITP and arthritis, including one reported in this issue of the JCI, now provide some insights into this mechanism and the rationale for the development of Fcγ receptor–targeted therapeutics.
Authors
Raphael Clynes
Abstract
Stromal cell–derived factor–1 (SDF-1) is a chemokine with unique functions, including a role in the trafficking of primitive blood precursor cells. A better understanding at a molecular level of how the binding of SDF-1 to its cell surface receptor, CXCR4, elicits specific biological responses in these cells has now been achieved through the identification of PKC-ζ activation as a common downstream signal. This finding suggests that treatment of a variety of clinical conditions might benefit from the targeting of PKC-ζ.
Authors
Connie J. Eaves
Abstract
Progression of hepatic fibrosis requires sustained inflammation leading to activation of stellate cells into a fibrogenic and proliferative cell type, whereas regression is associated with stellate cell apoptosis. The contribution of hepatic macrophages to these events has been largely overlooked. However, a study in this issue of the JCI demonstrates that macrophages play pivotal but divergent roles, favoring ECM accumulation during ongoing injury but enhancing matrix degradation during recovery. These findings underscore the potential importance of hepatic macrophages in regulating both stellate cell biology and ECM degradation during regression of hepatic fibrosis.
Authors
Scott L. Friedman
Abstract
Pregnane X receptor (PXR) plays an important role in detoxifying xenobiotics and drugs. In this issue of the JCI, Pascussi et al. provide convincing evidence that PXR can also induce vitamin D deficiency and bone disease because of its ability to cross-talk with the vitamin D–responsive gene that catabolizes 25-hydroxy-vitamin D and 1,25-dihydroxyvitamin D. This cross-talk behavior has important health ramifications and can be mitigated through the identification and treatment of PXR-induced vitamin D deficiency.
Authors
Michael F. Holick
Abstract
Platelets have long been suspected of having a role in cancer progression and metastasis that has largely been attributed to platelet-mediated enhancement of tumor cell survival, extravasation, and angiogenesis. A study in this issue of the JCI suggests that platelet-derived lysophosphatidic acid is coopted by aggressive breast and ovarian cancer cells as a tumor cell mitogen and promoter of osteolysis during bone metastasis.
Authors
Gaorav P. Gupta, Joan Massagué
Abstract
There has been some debate about the disease-invoking potential of Staphylococcus aureus strains and whether invasive disease is associated with particularly virulent genotypes, or “superbugs.” A study in this issue of the JCI describes the genotyping of a large collection of nonclinical, commensal S. aureus strains from healthy individuals in a Dutch population. Extensive study of their genetic relatedness by amplified restriction fragment typing and comparison with strains that are associated with different types of infections revealed that the S. aureus population is clonal and that some strains have enhanced virulence. This is discussed in the context of growing interest in the mechanisms of bacterial colonization, antibiotic resistance, and novel vaccines.
Authors
Timothy J. Foster
Abstract
The kidney adjusts net acid excretion to match production with exquisite precision, despite little or no change in the plasma bicarbonate concentration. The acid-sensing pathway that signals the kidney to increase acid secretion involves activation of the proto-oncogene c-Src. A new study in this issue shows that proline-rich tyrosine kinase 2 (Pyk2) is responsible for acid-induced activation of c-Src and is essential for acid sensing in renal epithelial cells. The findings implicate a broader role for Pyk2 in acid-base homeostasis in bone and other tissues beyond the kidney.
Authors
Stephen L. Gluck
Abstract
Innate immunity critically depends on signaling by Toll-like receptors (TLRs) that rely heavily on an intracellular adapter protein called myeloid differentiation factor 88 (MyD88). Adaptive immune defenses are generally thought to be orchestrated by innate immune responses and so should require intact TLR-MyD88 signaling pathways. But a surprising new study in MyD88-null mice infected with Mycobacterium tuberculosis challenges this view and instead suggests that MyD88 may not be absolutely required for a normal adaptive immune response.
Authors
Terence M. Doherty, Moshe Arditi
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