The Rho subgroup of the Rho GTPases consisting of RhoA, RhoB and RhoC induces a specific type of actin cytoskeleton and carry out a variety of functions in the cell. mDia and ROCK are downstream effectors of Rho mediating Rho action on the actin cytoskeleton; mDia produces actin filaments by nucleation and polymerization and ROCK activate myosin to cross-link them for induction of actomyosin bundles and contractility. mDia is potentially linked to Rac activation and membrane ruffle formation through c-Srcinduced phosphorylation of focal adhesion proteins, and ROCK antagonizes this mDia action. Thus, cell morphogenesis, adhesion, and motility can be determined by the balance between mDia and ROCK activities. Though they are not oncogenes by themselves, overexpression of RhoA and RhoC are often found in clinical cancers, and RhoC has been repeatedly identified as a gene associated with metastasis. The Rho-ROCK pathway is implicated in Ras-mediated transformation, the amoeboid movement of tumor cells in the threedimensional matrix, and transmigration of tumor cells through the mesothelial monolayer. On the other hand, the Rho-mDia1 pathway is implicated in Src-mediated remodeling of focal adhesions and migration of tumor cells. There is also an indication that the Rho pathway other than ROCK is involved in Src-mediated induction of podosome and regulation of matrix metalloproteases. Thus, Rho mediates various phenotypes of malignant transformation by Ras and Src through its effectors, ROCK and mDia.

Directed cell migration requires cell polarization and adhesion turnover, in which the actin cytoskeleton and microtubules work critically. The Rho GTPases induce specific types of actin cytoskeleton and regulate microtubule dynamics. In migrating cells, Cdc42 regulates cell polarity and Rac works in membrane protrusion. However, the role of Rho in migration is little known. Rho acts on two major effectors, ROCK and mDia1, among which mDia1 produces straight actin filaments and aligns microtubules. Here we depleted mDia1 by RNA interference and found that mDia1 depletion impaired directed migration of rat C6 glioma cells by inhibiting both cell polarization and adhesion turnover. Apc and active Cdc42, which work together for cell polarization, localized in the front of migrating cells, while active c-Src, which regulates adhesion turnover, localized in focal adhesions. mDia1 depletion impaired localization of these molecules at their respective sites. Conversely, expression of active mDia1 facilitated microtubule-dependent accumulation of Apc and active Cdc42 in the polar ends of the cells and actin-dependent recruitment of c-Src in adhesions. Thus, the Rho-mDia1 pathway regulates polarization and adhesion turnover by aligning microtubules and actin filaments and delivering Apc/Cdc42 and c-Src to their respective sites of action.Cell migration is indispensable in biological processes such as development, inflammation, wound healing, and tumor metastasis. Migrating cells polarize by extending protrusions at the front and retracting the tail at the rear, and make adhesions to extracellular matrix (ECM) to stabilize the forward protrusion (36). Adhesions to ECM are then used as sites to pull the cell body forward and are subsequently disassembled as the cell moves over them. This cycle of events enables cells to migrate to their destination. The actin cytoskeleton and microtubules (MTs) work critically in these events. Actin polymerization at the leading edge drives membrane protrusion, the association of the actin cytoskeleton with integrins regulates binding of the integrins to ECM, and the actin bundles within the body generate tension to pull the cell body forward and retract the tail. MTs are also polarized in migrating cells and are essential for the directed migration of many cell types (36, 37). However, how these cytoskeletons are regulated in migrating cells and work for cell polarization and adhesion turnover remains largely unknown.The Rho GTPases, including Rho, Rac, and Cdc42, work as molecular switches in cell morphogenesis by inducing specific types of actin cytoskeleton and by locally regulating MT dynamics. Accumulating evidence suggests that Cdc42 regulates cell polarity and Rac works in membrane protrusion of migrating cells. Indeed, Cdc42 is active at the cell front (17, 30), and disruption of Cdc42 function impairs directionality of migration in many cell types (1, 32). One well-characterized action of Cdc42 in cell polarity is to orient the MT organizing center (MTOC) in the front of the nucl...

OBJECTIVEMedulloblastoma is a type of malignant tumor arising in the cerebellum. The clinical importance of programmed cell death 1 ligand–1 (PD-L1) expression in medulloblastoma remains unknown. The aim of the present study was to examine the expression of PD-L1 and tumor-infiltrating T cells, and to evaluate their relationships to the prognosis of patients with medulloblastoma.METHODSThe authors immunohistochemically analyzed PD-L1 expression and CD3+ and CD8+ lymphocyte infiltrations in tumor specimens from 16 patients with medulloblastoma.RESULTSHigh expression of PD-L1 was observed in 9 (56.3%) of 16 samples studied. High expression of PD-L1 was associated with low infiltrations of CD3+ or CD8+ lymphocytes. Patients with high expression of PD-L1 had shorter progression-free survival and overall survival times than those with low expression (p = 0.076 and p = 0.099, respectively). In addition, patients with high expression of PD-L1 and with low infiltration of CD8+ lymphocytes had a significantly worse outcome, with a 5-year survival rate of 15%, as compared with the other patients, who had a 5-year survival rate of nearly 90% (p = 0.0048 for progression-free survival and p = 0.010 for overall survival).CONCLUSIONSThese findings indicate that PD-L1 expression was associated with a reduced infiltration of CD8+ T cells and poor prognosis in human medulloblastoma.

Despite the critical importance of Ca 2؉ /calmodulin (CaM)-dependent protein kinase (CaMK) II signaling in neuroplasticity, only a limited amount of work has so far been available regarding the presence and significance of another predominant CaMK subfamily, the CaMKI/CaMKIV family, in the central nervous system. We here searched for kinases with a core catalytic structure similar to CaMKI and CaMKIV. We isolated full-length cDNAs encoding three mouse CaMKI/CaMKIV-related kinases, CLICK-I (CL1)/doublecortin and CaM kinaseLike (DCAMKL)1, CLICK-II (CL2)/DCAMKL2, and CLICK-I,II-related (CLr)/DCAMKL3, the kinase domains of which had an intermediate homology not only to CaMKI/CaMKIV but also to CaMKII. Furthermore, CL1, CL2, and CLr were highly expressed in the central nervous system, in a neuron-specific fashion. CL1␣ and CL1␤ were shorter isoforms of DCAMKL1, which lacked the doublecortin-like domain (Dx). In contrast, CL2␣ and CL2␤ contained a full N-terminal Dx, whereas CLr only possessed a partial and dysfunctional Dx. Interestingly, despite a large similarity in the kinase domain, CL1/CL2/CLr had an impact on CRE-dependent gene expression distinct from that of the related CaMKI/CaMKIV and CaMKII. Although these were previously shown to activate Ca 2؉ /cAMP-response element-binding protein (CREB)-dependent transcription, we here show that CL1 and CL2 were unable to significantly phosphorylate CREB Ser-133 and rather inhibited CRE-dependent gene expression by a dominant mechanism that bypassed CREB and was mediated by phosphorylated TORC2.The availability of the human and other mammalian genome sequences provides a powerful means to dissect en masse the function of a particular class of proteins whose primary function can be deduced based on their primary sequences. The entire catalog of putative mammalian protein kinases, or kinome, has recently been established and curated (1, 2). This achievement per se is significant and now affords a better understanding of the biological role of kinases as regulatable switches under many physiologically and pathophysiologically critical circumstances. However, precise knowledge about the molecular characteristics of individual kinase molecules is still lacking (3).As part of the large list of serine/threonine and tyrosine kinase families, the Ca 2ϩ /calmodulin (CaM) 3 -dependent protein kinase (CaMK) group stands out by the large number of its constituent kinases (1-3). Despite its nomenclature, however, only the classic CaMK subgroups such as CaMKII family, or the CaMKI/CaMKIV family, are genuinely catalytically Ca 2ϩ /CaMdependent. Most of the kinases of the CaMK group actually lack the characteristic Ca 2ϩ /CaM-sensitive regulatory domain. They nonetheless belong to the CaMK group, because they share in common a significant homology in the primary structure of their kinase domains. Several classic CaMKs such as CaMKII and CaMKIV are highly expressed in the central nervous system and have been convincingly shown to play a critical role in long term synaptic plasticity and...

tal-1 (T-cell acute leukemia-1; also known as SCL) and tal-2 genes belong to a family of basic helix-loop-helix transcription factors and were originally isolated from the breakpoints of chromosomal translocations in human T-cell leukemia cell lines. tal-1 is expressed not only in hematopoietic cells but also in several endothelial structures and the central nervous system during development. On the other hand, the detailed function and the sites of expression of tal-2 have remained obscure. We cloned the tal-2 cDNA from a mouse embryonic cDNA library and examined its expression pattern in the mouse, comparing with that of tal-1. In situ analyses revealed that tal-2 transcripts are detected at embryonic day 12.5 in the following regions; 1) the diencephalon-the zona limitans intrathalamica and the pretectum, 2) the mesencephalon-the tectum, and the anterior and posterior tegmentum, 3) the metencephalon-the isthmus and the anterior pons. In the diencephalon and the mesencephalon, the expression sites of tal-2 gene were similar to those of tal-1, and its expression was stronger than that of tal-1. In the metencephalon, tal-2 expression was observed in the anterior pons, whereas tal-1 transcripts were detected in the entire pons, and showed stronger expression than tal-2. The tal-2 messages were barely detectable in the brain at birth. These results suggest that tal-1 and tal-2 are involved in the development of specific areas of the central nervous system.