Localization of the Rab escort protein-2 (REP2) and inositol 1,4,5-trisphosphate 3-kinase (ITPKB) genes to mouse chromosome 1 by in situ hybridization and precision of the syntenic regions between mouse and human 1q42-q44

High expression of CHML predicts poor prognosis of multiple myeloma

Multiple myeloma is a hematological tumor with a malignant proliferation of myeloma cells. Although the survival time after treatment has improved, the recurrence rate of MM is still high. Choroideremia-like (CHML) protein is essential for the prenylation modification of various Rab proteins and it exerts biological effects on vesicle trafficking and signal transduction. However, little is identified about the relationship between CHML gene and MM. We integrated gene expression profiles of 1907 MM patients (1959 MM samples) from the 7 datasets. The relationship between CHML gene expression level and event-free survival (EFS), overall survival (OS), ISS stage, molecular subtype, relapse, therapy was analyzed. The differential gene exression profile of CHML-high MM group and CHML-low MM group and possible pathway related to CHML were conducted. Our data showed that EFS (P < 0.0001) and OS (P < 0.0001) in MM patients with high expression of CHML were lower than those with low CHML expression. The gene expression level of CHML was increased in subtypes of MM with poor prognosis, especially in proliferation subtype (P < 0.001). Cell division pathway (P < 0.01) was high enriched of the differential expressed genes of CHML-high group vs CHML-low group. CHML gene can be considered as an independent factor to evaluate the prognosis of MM. High expression of CHML is associated with poor survival, which is related to cell proliferation and cell division of myeloma cells.

Inositol 1,4,5-trisphosphate 3-kinase B (Itpkb) controls survival, proliferation and cytokine production in mouse peripheral T cells

Mice genetically-deficient for the B isoform of the inositol 1,4,5-trisphosphate 3-kinase (or Itpkb) have a severe defect in thymocytes differentiation and thus lack peripheral T cells. In order to study the functional role of Itpkb in peripheral T cells, we constructed a new mouse where a transgene encoding mouse Itpkb is specifically and transiently expressed in thymocytes of Itpkb(-)(/)(-) mice. This allows a partial rescue of mature thymocyte/T cell differentiation and thus the functional characterization of peripheral T cells lacking Itpkb. We show here that Itpkb(-)(/)(-) CD4(+) and CD8(+) peripheral T cells present important functional alterations. Indeed, an increased activated/memory phenotype as well as a decreased proliferative capacity and survival were detected in these T cells. These Itpkb-deficient peripheral T cells have also an increased capacity to secrete cytokines upon stimulation. Together, our present results define the important role of Itpkb in peripheral mature T cell fate and function in mouse, suggesting a potential role for Itpkb in autoimmunity.

Human inositol 1,4,5-trisphosphate 3-kinase isoform B (IP3KB) is a nucleocytoplasmic shuttling protein specifically enriched at cortical actin filaments and at invaginations of the nuclear envelope

Recent studies have shown that inositol 1,4,5-trisphosphate 3-kinase isoform B (IP3KB) possesses important roles in the development of immune cells. IP3KB can be targeted to multiple cellular compartments, among them nuclear localization and binding in close proximity to the plasma membrane. The B isoform is the only IP3K that is almost ubiquitously expressed in mammalian cells. Detailed mechanisms of its targeting regulation will be important in understanding the role of Ins(1,4,5)P(3) phosphorylation on subcellular calcium signaling and compartment-specific initiation of pathways leading to regulatory active higher phosphorylated inositol phosphates. Here, we identified an exportin 1-dependent nuclear export signal ((134)LQRELQNVQV) and characterized the amino acids responsible for nuclear localization of IP3KB ((129)RKLR). These two targeting domains regulate the amount of nuclear IP3KB in cells. We also demonstrated that the localization of IP3KB at the plasma membrane is due to its binding to cortical actin structures. Intriguingly, all three of these targeting activities reside in one small polypeptide segment (amino acids 104-165), which acts as a multitargeting domain (MTD). Finally, a hitherto unknown subnuclear localization of IP3KB could be demonstrated in rapidly growing H1299 cells. IP3KB is specifically enriched at nuclear invaginations extending perpendicular between the apical and basal surface of the nucleus of these flat cells. Such nuclear invaginations are known to be involved in Ins(1,4,5)P(3)-mediated Ca(2+) signaling of the nucleus. Our findings indicate that IP3KB not only regulates cytoplasmic Ca(2+) signals by phosphorylation of subplasmalemmal and cytoplasmic Ins(1,4,5)P(3) but may also be involved in modulating nuclear Ca(2+) signals generated from these nuclear envelope invaginations.

Homozygosity and linkage-disequilibrium mapping of the syndrome of congenital hypoparathyroidism, growth and mental retardation, and dysmorphism to a 1-cM interval on chromosome 1q42-43

The syndrome of hypoparathyroidism associated with growth retardation, developmental delay, and dysmorphism (HRD) is a newly described, autosomal recessive, congenital disorder with severe, often fatal consequences. Since the syndrome is very rare, with all parents of affected individuals being consanguineous, it is presumed to be caused by homozygous inheritance of a single recessive mutation from a common ancestor. To localize the HRD gene, we performed a genomewide screen using DNA pooling and homozygosity mapping for apparently unlinked kindreds. Analysis of a panel of 359 highly polymorphic markers revealed linkage to D1S235. The maximum LOD score obtained was 4.11 at a recombination fraction of 0. Analysis of three additional markers-GGAA6F06, D1S2678, and D1S179-in a 2-cM interval around D1S235 resulted in LOD scores >3. Analysis of additional chromosome 1 markers revealed evidence of genetic linkage disequilibrium and place the HRD locus within an approximately 1-cM interval defined by D1S1540 and D1S2678 on chromosome 1q42-43.