WNT5B in Physiology and Disease

WNT5B, a member of the WNT family of proteins that is closely related to WNT5A, is required for cell migration, cell proliferation, or cell differentiation in many cell types. WNT5B signals through the non-canonical β-catenin-independent signaling pathway and often functions as an antagonist of canonical WNT signaling. Although WNT5B has a high amino acid identity with WNT5A and is often assumed to have similar activities, WNT5B often exhibits unique expression patterns and functions. Here, we describe the distinct effects and mechanisms of WNT5B on development, bone, adipose tissue, cardiac tissue, the nervous system, the mammary gland, the lung and hematopoietic cells, compared to WNT5A. We also highlight aberrances in non-canonical WNT5B signaling contributing to diseases such as osteoarthritis, osteoporosis, obesity, type 2 diabetes mellitus, neuropathology, and chronic diseases associated with aging, as well as various cancers.

Melanocortin Receptor 4 (MC4R) Signaling System in Nile Tilapia

The melanocortin receptor 4 (MC4R) signaling system consists of MC4R, MC4R ligands [melanocyte-stimulating hormone (MSH), adrenocorticotropin (ACTH), agouti-related protein (AgRP)], and melanocortin-2 receptor accessory protein 2 (MRAP2), and it has been proposed to play important roles in feeding and growth in vertebrates. However, the expression and functionality of this system have not been fully characterized in teleosts. Here, we cloned tilapia MC4R, MRAP2b, AgRPs (AgRP, AgRP2), and POMCs (POMCa1, POMCb) genes and characterized the interaction of tilapia MC4R with MRAP2b, AgRP, α-MSH, and ACTH in vitro. The results indicate the following. (1) Tilapia MC4R, MRAP2b, AgRPs, and POMCs share high amino acid identity with their mammalian counterparts. (2) Tilapia MRAP2b could interact with MC4R expressed in CHO cells, as demonstrated by Co-IP assay, and thus decrease MC4R constitutive activity and enhance its sensitivity to ACTH1-40. (3) As in mammals, AgRP can function as an inverse agonist and antagonist of MC4R, either in the presence or absence of MRAP2b. These data, together with the co-expression of MC4R, MRAP2b, AgRPs, and POMCs in tilapia hypothalamus, suggest that as in mammals, ACTH/α-MSH, AgRP, and MRAP2 can interact with MC4R to control energy balance and thus play conserved roles in the feeding and growth of teleosts.

The unprecedented diversity of UGT94-family UDP-glycosyltransferases in Panax plants and their contribution to ginsenoside biosynthesis

More than 150 ginsenosides have been isolated and identified from Panax plants. Ginsenosides with different glycosylation degrees have demonstrated different chemical properties and bioactivity. In this study, we systematically cloned and characterized 46 UGT94 family UDP-glycosyltransferases (UGT94s) from a mixed Panax ginseng/callus cDNA sample with high amino acid identity. These UGT94s were found to catalyze sugar chain elongation at C3-O-Glc and/or C20-O-Glc of protopanaxadiol (PPD)-type, C20-O-Glc or C6-O-Glc of protopanaxatriol (PPT)-type or both C3-O-Glc of PPD-type and C6-O-Glc of PPT-type or C20-O-Glc of PPD-type and PPT-type ginsenosides with different efficiencies. We also cloned 26 and 51 UGT94s from individual P. ginseng and P. notoginseng plants, respectively; our characterization results suggest that there is a group of UGT94s with high amino acid identity but diverse functions or catalyzing activities even within individual plants. These UGT94s were classified into three clades of the phylogenetic tree and consistent with their catalytic function. Based on these UGT94s, we elucidated the biosynthetic pathway of a group of ginsenosides. Our present results reveal a series of UGTs involved in second sugar chain elongation of saponins in Panax plants, and provide a scientific basis for understanding the diverse evolution mechanisms of UGT94s among plants.

Complete Genome Sequence of Murine Pneumotropic Virus (Polyomaviridae) Clone pKV(37-1)

The murine pneumotropic virus genome encoded by the pKV(37-1) clone was sequenced to completion. The regulatory region harbored a mutation not previously reported. The protein coding regions (large and small T antigens, viral proteins 1 to 3) showed multiple regions of high amino acid identity to the human, simian, and bovine polyomaviruses.

Mouse SGLT3a generates proton-activated currents but does not transport sugar

Sodium-glucose cotransporters (SGLTs) are secondary active transporters belonging to the SLC5 gene family. SGLT1, a well-characterized member of this family, electrogenically transports glucose and galactose. Human SGLT3 (hSGLT3), despite sharing a high amino acid identity with human SGLT1 (hSGLT1), does not transport sugar, although functions as a sugar sensor. In contrast to humans, two different genes in mice and rats code for two different SGLT3 proteins, SGLT3a and SGLT3b. We previously cloned and characterized mouse SGLT3b (mSGLT3b) and showed that, while it does transport sugar like SGLT1, it likely functions as a physiological sugar sensor like hSGLT3. In this study, we cloned mouse SGLT3a (mSGLT3a) and characterized it by expressing it in Xenopus laevis oocytes and performing electrophysiology and sugar transport assays. mSGLT3a did not transport sugar, and sugars did not induce currents at pH 7.4, though acidic pH induced inward currents that increased in the presence of sugar. Moreover, mutation of residue 457 from glutamate to glutamine resulted in a Na+-dependent transport of sugar that was inhibited by phlorizin. To corroborate our results in oocytes, we expressed and characterized mSGLT3a in mammalian cells and confirmed our findings. In addition, we cloned, expressed, and characterized rat SGLT3a in oocytes and found characteristics similar to mSGLT3a. In summary, acidic pH induces currents in mSGLT3a, and sugar-induced currents are increased at acidic pH, but wild-type SGLT3a does not transport sugar.

Cloning of a Gene Encoding Raw-Starch-Digesting Amylase from a Cytophaga sp. and Its Expression in Escherichia coli

ABSTRACT A raw-starch-digesting amylase (RSDA) gene from a Cytophaga sp. was cloned and sequenced. The predicted protein product contained 519 amino acids and had high amino acid identity to α-amylases from three Bacillus species. Only one of the Bacillus α-amylases has raw-starch-digesting capability, however. The RSDA, expressed in Escherichia coli, had properties similar to those of the enzyme purified from the Cytophaga sp.