Lrig1 is an estrogen-regulated growth suppressor and correlates with longer relapse-free survival in ERα-positive breast cancer.

Lrig1 is the founding member of the Lrig family and has been implicated in the negative regulation of several oncogenic receptor tyrosine kinases including ErbB2. Lrig1 is expressed at low levels in several cancer types but is overexpressed in some prostate and colorectal tumors. Given this heterogeneity, whether Lrig1 functions to suppress or promote tumor growth remains a critical question.

Inhibitory mechanism of pure curcumin on Wilms' tumor 1 (WT1) gene expression through the PKCα signaling pathway in leukemic K562 cells.

The aim of this study was to investigate the inhibitory mechanism of pure curcumin on WT1 expression in leukemic K562 cells. Pure curcumin suppressed WT1 expression, independent of effects on protein degradation or WT1 mRNA stability. Chromatin immunoprecipitation and reporter gene assays indicate that pure curcumin treatment attenuates WT1 auto-regulation.

Mechanisms of ErbB receptor negative regulation and relevance in cancer.

The ErbB family of receptor tyrosine kinases engages a wide variety of signaling pathways that collectively direct transcriptional programs controlling organogenesis during development and tissue maintenance in the adult. These receptors are also frequently found overexpressed or aberrantly activated in various cancers, suggesting that ErbB receptor signaling activity must be very tightly regulated. Sufficient levels of ErbB signaling are necessary to mediate tissue homeostasis, for example, but over-signaling can trigger cellular processes that contribute to cancer initiation or progression.

Degradation of several hypomodified mature tRNA species in Saccharomyces cerevisiae is mediated by Met22 and the 5'-3' exonucleases Rat1 and Xrn1.

Mature tRNA is normally extensively modified and extremely stable. Recent evidence suggests that hypomodified mature tRNA in yeast can undergo a quality control check by a rapid tRNA decay (RTD) pathway, since mature tRNA(Val(AAC)) lacking 7-methylguanosine and 5-methylcytidine is rapidly degraded and deacylated at 37 degrees C in a trm8-Delta trm4-Delta strain, resulting in temperature-sensitive growth. We show here that components of this RTD pathway include the 5'-3' exonucleases Rat1 and Xrn1, and Met22, which likely acts indirectly through Rat1 and Xrn1.

Identification of yeast tRNA Um(44) 2'-O-methyltransferase (Trm44) and demonstration of a Trm44 role in sustaining levels of specific tRNA(Ser) species.

A characteristic feature of tRNAs is the numerous modifications found throughout their sequences, which are highly conserved and often have important roles. Um(44) is highly conserved among eukaryotic cytoplasmic tRNAs with a long variable loop and unique to tRNA(Ser) in yeast. We show here that the yeast ORF YPL030w (now named TRM44) encodes tRNA(Ser) Um(44) 2'-O-methyltransferase.

Identification and characterization of modification enzymes by biochemical analysis of the proteome.

The use of proteomic libraries designed to express the complete set of proteins from an organism has resulted in the identification of many RNA modification enzymes whose function was previously unknown. Here we describe a generalized procedure for the biochemical analysis of a yeast proteomic library for identification of nucleic acid-modifying enzymes, by use of the yeast MORF (Moveable Open Reading Frame) library (Gelperin et al., 2005) as the source of protein activity, and the known yeast tRNA methyltransferase Trm4 as a test case.