Implications of CLSPN Variants in Cellular Function and Susceptibility to Cancer.

Claspin is a multifunctional protein that participates in physiological processes essential for cell homeostasis that are often defective in cancer, namely due to genetic changes. It is conceivable that Claspin gene (CLSPN) alterations may contribute to cancer development. Therefore, CLSPN germline alterations were characterized in sporadic and familial breast cancer and glioma samples, as well as in six cancer cell lines. Their association to cancer susceptibility and functional impact were investigated. Eight variants were identified (c.-68C>T, c.17G>A, c.1574A>G, c.2230T>C, c.2028+16G>A, c.3595-3597del, and c.3839C>T). CLSPN c.1574A>G (p.Asn525Ser) was significantly associated with breast cancer and was shown to cause partial exon skipping and decreased Claspin expression and Chk1 activation in a minigene splicing assay and in signalling experiments, respectively. CLSPN c.2028+16G>A was significantly associated with familial breast cancer and glioma, whereas c.2230T>C (p.Ser744Pro), was exclusively detected in breast cancer and glioma patients, but not in healthy controls. The remaining variants lacked a significant association with cancer. Nevertheless, the c.-68C>T promoter variant increased transcriptional activity in a luciferase assay. In conclusion, some of the CLSPN variants identified in the present study appear to modulate Claspin's function by altering CLSPN transcription and RNA processing, as well as Chk1 activation.

Knocking out of CD38 accelerates development of a lupus-like disease in lpr mice.

OBJECTIVES: CD38 participates in lymphocyte ontogeny and function and may be involved in autoimmunity. Absence of CD38 accelerates development of non-obese diabetic (NOD) mice diabetes and anti-CD38 antibodies are good markers of human disease. Little is known regarding systemic autoimmunity. Active SLE patients have higher numbers of CD38(+) T and B cells. CD38 is a candidate gene for the murine Lmb2 lupus locus. We aimed to investigate whether CD38 was involved in lupus development. METHODS: We developed Cd38(-/-)-Fas(lpr)/Fas(lpr) mice and monitored them for development of a lupus-like disease through measurement of protein excretion in urine, histological assessment of the kidneys, quantification of circulating immunoglobulins and autoantibodies. We have also immunophenotyped 2- and 6-month old Cd38(-/-)-Fas(lpr)/Fas(lpr) mice. RESULTS: We found that absence of CD38 accelerated disease development: female Cd38(-/-)-Fas(lpr)/Fas(lpr) mice presented severe proteinuria, GN, deposition of ICs in the renal medulla and increased amounts of circulating immunoglobulin G (IgG), although anti-dsDNA autoantibodies and RF were not significantly increased at disease onset. We have found that Cd38(-/-)-Fas(lpr)/Fas(lpr) male mice, similarly to other murine models of lupus, were able to control disease. Absence of CD38 in lpr mice altered differentiation of T cells and dendritic cells (DC). CONCLUSION: Although the role of CD38 in tolerance is still to be elucidated, we provide evidence that it may play an active role in the control of a murine lupus-like disease.

CD38 plays a role in effective containment of mycobacteria within granulomata and polarization of Th1 immune responses against Mycobacterium avium.

CD38 is a multifunctional ectoenzyme that behaves either as an enzyme, a cell adhesion molecule or as a cell surface receptor involved in cell signalling. It is expressed in cells of several lineages, including B and T lymphocytes, and macrophages. CD38 was shown to be important for the development of T-cell dependent humoral immune responses against extracellular pathogens. It also appears to be functionally important in macrophages, which are the host cells of Mycobacterium avium, an intracellular parasite that survives within these cells by avoiding a number of their microbicidal strategies. The present work aimed at investigating whether CD38 had any role on the immune response against mycobacterial infection. After intraperitoneal M. avium infection, the immune response of CD38KO mice was compared to that of their parental strain, C57Bl.6 mice. Absence of CD38 rendered mice more susceptible to mycobacterial infection. This susceptibility seems to be due to ineffective Th1 differentiation and polarization, which is essential for the control of M. avium infection. In addition, absence of CD38 seems to compromise the maintenance of the granulomatous barrier, leading to dissemination and unrestrained growth of mycobacteria.