Sonic hedgehog enhances calcium oscillations in hippocampal astrocytes.

Sonic hedgehog (SHH) is important for organogenesis during development. Recent studies have indicated that SHH is also involved in the proliferation and transformation of astrocytes to the reactive phenotype. However, the mechanisms underlying these are unknown.

Depletion of tumor suppressor Kank1 induces centrosomal amplification via hyperactivation of RhoA.

Chromosome instability, frequently found in cancer cells, is caused by a deficiency in cell division, including centrosomal amplification and cytokinesis failure, and can result in abnormal chromosome content or aneuploidy. The small GTPase pathways have been implicated as important processes in cell division. We found that knockdown of a tumor suppressor protein Kank1 increases the number of cells with a micronucleus or bi-/multi-nuclei, which was likely caused by centrosomal amplification.

Association of nonsense mutation in GABRG2 with abnormal trafficking of GABAA receptors in severe epilepsy.

Mutations in GABRG2, which encodes the γ2 subunit of GABAA receptors, can cause both genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome. Most GABRG2 truncating mutations associated with Dravet syndrome result in premature termination codons (PTCs) and are stably translated into mutant proteins with potential dominant-negative effects. This study involved search for mutations in candidate genes for Dravet syndrome, namely SCN1A, 2A, 1B, 2B, GABRA1, B2, and G2.

Multiple primary cilia modulate the fluid transcytosis in choroid plexus epithelium.

Functional defects in cilia are associated with various human diseases including congenital hydrocephalus. Previous studies suggested that defects in cilia not only disrupt the flow of cerebrospinal fluid (CSF) generated by motile cilia in ependyma lining the brain ventricles, but also cause increased CSF production at the choroid plexus. However, the molecular mechanisms of CSF overproduction by ciliary dysfunction remain elusive.

A major mutation of KIF21A associated with congenital fibrosis of the extraocular muscles type 1 (CFEOM1) enhances translocation of Kank1 to the membrane.

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1) is associated with heterozygous mutations in the KIF21A gene, including a major (R954W) and a minor (M947T) mutation. Kank1, which regulates actin polymerization, cell migration and neurite outgrowth, interacted with the third and fourth coiled-coil domains of KIF21A protein at its ankyrin-repeat domain. While both KIF21A(R954W) and KIF21A(M947T) enhanced the formation of a heterodimer with the wild type, KIF21A(WT), these mutants also enhanced the interaction with Kank1.

Kank attenuates actin remodeling by preventing interaction between IRSp53 and Rac1.

In this study, insulin receptor substrate (IRS) p53 is identified as a binding partner for Kank, a kidney ankyrin repeat-containing protein that functions to suppress cell proliferation and regulate the actin cytoskeleton. Kank specifically inhibits the binding of IRSp53 with active Rac1 (Rac1(G12V)) but not Cdc42 (cdc42(G12V)) and thus inhibits the IRSp53-dependent development of lamellipodia without affecting the formation of filopodia. Knockdown (KD) of Kank by RNA interference results in increased lamellipodial development, whereas KD of both Kank and IRSp53 has little effect.

Kank regulates RhoA-dependent formation of actin stress fibers and cell migration via 14-3-3 in PI3K-Akt signaling.

Phosphoinositide-3 kinase (PI3K)/Akt signaling is activated by growth factors such as insulin and epidermal growth factor (EGF) and regulates several functions such as cell cycling, apoptosis, cell growth, and cell migration. Here, we find that Kank is an Akt substrate located downstream of PI3K and a 14-3-3-binding protein. The interaction between Kank and 14-3-3 is regulated by insulin and EGF and is mediated through phosphorylation of Kank by Akt.

Kank proteins: a new family of ankyrin-repeat domain-containing proteins.

The human Kank gene was found as a candidate tumor suppressor for renal cell carcinoma, and encodes an ankyrin-repeat domain-containing protein, Kank. Here, we report a new family of proteins consisting of three Kank (Kank1)-associated members, Kank2, Kank3 and Kank4, which were found by domain and phylogenetic analyses. Besides the conserved ankyrin-repeat and coiled-coil domains, there was a conserved motif at the N-terminal (KN motif) containing potential motifs for nuclear localization and export signals.

Nucleo-cytoplasmic shuttling of human Kank protein accompanies intracellular translocation of beta-catenin.

The human Kank protein has a role in controlling the formation of the cytoskeleton by regulating actin polymerization. Besides the cytoplasmic localization as reported before, we observed the nuclear localization of Kank in OS-RC-2 cells. To uncover the mechanism behind this phenomenon, we focused on the nuclear localization signal (NLS) and the nuclear export signal (NES).

Alternative splicing of the human Kank gene produces two types of Kank protein.

The human Kank gene encodes an ankyrin repeat domain-containing protein which regulates actin polymerization. There are at least two types of Kank protein depending on cell type, likely due to differences in transcription. Here, to examine the transcriptional initiation and genomic organization of the human Kank gene, we performed 5'-RACE (rapid amplification of cDNA ends) using total RNA from normal kidney and a human kidney cancer cell line, VMRC-RCW cells.

Cloning of novel LERGU mRNAs in GPR30 3' untranslated region and detection of 2 bp-deletion polymorphism in gastric cancer.

The improved IGCR (In-Gel Competitive Reassociation) method was applied to the analysis of human gastric cancer genomic DNA to identify its alterations, and it appeared that the IGCR library contained a fragment of 3'-untranslated region (3' UTR) of G-protein coupled receptor 30 (GPR30) mRNA. When we searched genomic DNA pairs of gastric cancer patients with this IGCR clone, we found the deletion polymorphism with or without 2 bp (Cytosine and Thymine; CT). We confirmed the existence of a novel mRNA in GPR30 3'UTR by northern blotting, cloned this novel mRNA and named it Leucine Rich Protein in GPR30 3'UTR (LERGU).

Candidate regions of tumor suppressor gene by loss of heterozygosity analysis on chromosome 8p11.1-q13.3 in gastric cancer.

Loss of heterozygosity (LOH) is an important event of tumorigenesis. In this paper, we report the comprehensive LOH analyses with microsatellite markers and their results at chromosome 8p11.1-q13.

Candidate regions of tumor suppressor locus on chromosome 9q31.1 in gastric cancer.

Loss of heterozygosity (LOH) is an important event of tumorigenesis. In gastric cancer, we found a novel region of LOH in chromosome 9q having about 800 kb deletions at 9q31.1.

Expression and localization of the LGN protein in the mouse brain with reference to its relationship with Galphai2.

It has been suggested that the LGN protein is associated with Galphai2 by the yeast two-hybrid system and in vitro pull-down assay. To determine the functions of LGN in the central nervous system, we examined the expression and localization of LGN in mouse brain by immunoblotting and immunofluorescence microscopy. By immunoblotting, almost similar amounts of LGN were detected in the olfactory bulb, cerebral cortex, hippocampus, and cerebellum of the adult mouse brain, and the levels of the postnatal LGN expression in the whole brain were fairly constant.