TJP2 Research Articles

Sorting nexin 27 (SNX27) associates with zonula occludens-2 (ZO-2) and modulates the epithelial tight junction

Proteins of the SNX (sorting nexin) superfamily are characterized by the presence of a PX (Phox homology) domain and associate with PtdIns3P (phosphatidylinositol-3-monophosphate)-rich regions of the endosomal system. SNX27 is the only sorting nexin that contains a PDZ domain. In the present study, we used a proteomic approach to identify a novel interaction between SNX27 and ZO-2 [zonula occludens-2; also known as TJP2 (tight junction protein 2)], a component of the epithelial tight junction. The SNX27-ZO-2 interaction requires the PDZ domain of SNX27 and the C-terminal PDZ-binding motif of ZO-2. When tight junctions were perturbed by chelation of extracellular Ca2+, ZO-2 transiently localized to SNX27-positive early endosomes. Depletion of SNX27in mpkCCD (mouse primary kidney cortical collecting duct) cell monolayers resulted in a decrease in the rate of ZO-2, but not ZO-1, mobility at cell-cell contact regions after photobleaching and an increase in junctional permeability to large solutes. The findings of the present study identify an important new SNX27-binding partner and suggest a role for endocytic pathways in the intracellular trafficking of ZO-2 and possibly other tight junction proteins. Our results also indicate a role for SNX27-ZO-2 interactions in tight junction maintenance and function.

TJP2 (tight junction protein 2 (zona occludens 2))

Review on TJP2 (tight junction protein 2 (zona occludens 2)), with data on DNA, on the protein encoded, and where the gene is implicated.

Correlation of tight junction protein-2 expression and localization with pancreatic cancer cell dissociation

Correlation of tight junction protein-2 expression and localization with pancreatic cancer cell dissociation

Analysis of invasion-metastasis in pancreatic cancer: Correlation between the expression and arrangement of tight junction protein-2 and cell dissociation in pancreatic cancer cells

High frequency of invasion and metastasis is one of the key characteristics of pancreatic cancer. In our recent study, tight junction protein-2 (Tjp-2) was identified as a differentially expressed gene related to invasion-metastasis in highly (PC-1.0) and weakly (PC-1) invasive and metastatic pancreatic cancer cells by cDNA microarray analysis. Changes in the structure and function of tight junctions are correlated with carcinogenesis and tumour development. In this study, RT-PCR, Western blotting and immunocytochemistry were used to study the correlation between the expression and localisation of Tjp-2 and cell dissociation in pancreatic cancer. Tjp-2 mRNA and protein were differentially expressed in PC-1.0 and PC-1 cells. Furthermore, the addition of dissociation factor (DF) or U0126 (a MEK inhibitor) significantly induced changes in the mRNA expression and protein intracellular localisation of Tjp-2, and in the simultaneous cell dissociation of PC-1.0 and PC-1 cells. However, protein expression of Tjp-2 was not affected by DF or U0126 treatment. The current results indicate that Tjp-2 is involved in the regulation of cell dissociation in pancreatic cancer cells through changes in gene expression and intracellular localisation. Tjp-2 may serve as a new target for molecular therapies that prevent the invasion and metastasis of pancreatic cancer.

Relationship between Gene Expression and Enhancement in Glioblastoma Multiforme: Exploratory DNA Microarray Analysis

To determine the difference in gene expression between completely versus incompletely enhancing glioblastoma multiforme (GBM). Gene expression was determined for 52 newly diagnosed GBMs by using DNA microarrays, and the relationship to enhancement pattern and survival was analyzed. This study was approved by the institutional review board and was HIPAA compliant; informed consent was obtained. Thirty-eight percent (20 of 52) of GBMs were incompletely enhancing (IE). The expression of eight genes was increased more than twofold in IE GBM when compared with completely enhancing (CE) GBM. Among these were tight junction protein-2 (2.2-fold increase, P = .019), and the oligodendroglioma markers oligodendrocyte lineage transcription factor 2 (2.4-fold increase, P = .029) and Achaete-scute complex-like 1 (ASCL1; 2.7-fold increase, P = .023). The expression of 71 genes showed relative overexpression in CE when compared with IE GBM. These included several proangiogenic and edema-related genes, including vascular endothelial growth factor (2.1-fold, P = .005) and neuronal pentraxin-2 (3.0-fold, P = .029). Several genes associated with primary GBM were overexpressed in CE tumors, whereas ASCL1, which is associated with secondary GBM, was overexpressed in IE tumors. Many genes overexpressed in IE GBM were associated with longer survival, whereas several genes overexpressed in CE GBM correlated with shortened survival. The enhancement pattern divides GBM in two groups with differing prognoses. By comparing gene expression between IE and CE GBMs, it was possible to identify genes that may affect magnetic resonance imaging features of edema and enhancement, and genes whose expression levels are predictive of both improved and shortened survival.

ACTION OF HECKE OPERATORS ON SIEGEL THETA SERIES I

We apply the Hecke operators T(p) and [Formula: see text] to a degree n theta series attached to a rank 2k ℤ-lattice L, n ≤ k, equipped with a positive definite quadratic form in the case that L/pL is hyperbolic. We show that the image of the theta series under these Hecke operators can be realized as a sum of theta series attached to certain closely related lattices, thereby generalizing the Eichler Commutation Relation (similar to some work of Freitag and of Yoshida). We then show that the average theta series (averaging over isometry classes in a given genus) is an eigenform for these operators. We show the eigenvalue for T(p) is ∊(k - n, n), and the eigenvalue for T′j(p2) (a specific linear combination of T0(p2),…,Tj(p2)) is pj(k-n)+j(j-1)/2β(n,j)∊(k-j,j) where β(*,*), ∊(*,*) are elementary functions (defined below).

Explicit Action of Hecke Operators on Siegel Modular Forms

We develop an algorithm for determining an explicit set of coset representatives (indexed by lattices) for the action of the Hecke operators T(p), Tj(p2) on Siegel modular forms of fixed degree and weight. This algorithm associates each coset representative with a particular lattice Ω, pΛ⊆Ω⊆1pΛ where Λ is a fixed reference lattice. We then evaluate the action of the Hecke operators on Fourier series. Since this evaluation yields incomplete character sums for Tj(p2), we complete these sums by replacing this operator with a linear combination of Tℓ(p2), 0⩽ℓ⩽j. In all cases, this yields a clean and simple description of the action on Fourier coefficients.