Phosphatidic acid phosphatase is a fat-regulating enzyme that plays a major role in controlling the balance of phosphatidic acid (substrate) and diacylglycerol (product), which are lipid precursors used for the synthesis of membrane phospholipids and triacylglycerol. Phosphatidic acid is also a signaling molecule that triggers phospholipid synthesis gene expression, membrane expansion, secretion, and endocytosis. While this important enzyme has been known for several decades, its gene was only identified recently from yeast. This discovery showed the importance of phosphatidic acid phosphatase in lipid metabolism in yeast as well as in higher eukaryotes including humans.
The MBOAT enzyme family, identified in 2000, comprises 11 genes in the human genome that participate in a variety of biological processes. MBOAT enzymes contain multiple transmembrane domains and share two active site residues, histidine and asparagine. Several MBOAT members are drug targets for major human diseases, including atherosclerosis, obesity, Alzheimer disease, and viral infections. Here we review the historical aspects of MBOAT enzymes, classify them biochemically into 3 subgroups, and describe the essential features of each member.
Lipids, once thought to be mainly for energy-storage and structural purpose, have now gained immense recognition as a class of critical metabolites with versatile functions. The diversity and complexity of the cellular lipids are the main challenge for the comprehensive analysis of a lipidome. Lipidomics, which aims at mapping all of the lipids in a cell, is expanded rapidly in recent years, mainly attributed to recent advances in mass spectrometry (MS). MS-based lipidomic approaches developed recently allow the quick profiling of hundreds of lipids in a crude lipid extract. With the aid of latest computational tools/software (chemometrics), aberrant lipid metabolites or important signaling lipid(s) could be easily identified using unbiased lipid profiling approaches. Further tandem MS (MS/MS)-based lipidomic approaches, known as targeted approaches and able to convey structural information, hold the promise for high-throughput lipidome analysis. In this review, I discussed the basic strategy for systems level analysis of lipidome in biomedical study.
Endosomal compartments sort and deliver exogenous lipoprotein-derived cholesterol to the endoplasmic reticulum for regulating cellular cholesterol homeostasis. A large number of studies have focused on the removal of endosomal cholesterol, since its accumulation leads to devastating human diseases. Recent studies suggest that cytoplasmic sterol-binding proteins may be involved in endosomal cholesterol transport. In particular, endosome/lysosome-localized or-associated cholesterol-binding proteins may serve as key mediators of cholesterol removal in a non-vesicular manner. Further characterization of these cholesterol-binding proteins will shed light on the molecular mechanisms that regulate endosomal cholesterol sorting.
In this review, we aim to convey a brief, select history of the development of cholesterol-lowering therapies. We focus particularly on the highly successful statins as well as setbacks that should serve as cautionary tales. We go on to preview recent developments that may complement, if not one day replace, the statins. Our focus is on pharmacological interventions, particularly those targeting the cholesterol biosynthetic pathway. Also, we examine therapies under current investigation that target the assembly of atherogenic lipoproteins (via apolipoprotein B or microsomal triglyceride transfer protein), the stability of the low-density lipoprotein-receptor (via PCSK9, proprotein convertase subtilisin kexin 9), or are designed to increase high-density lipoprotein-cholesterol (via inhibition of cholesteryl ester transfer protein).
Obesity is associated with the higher risk of breast cancer in postmenopausal women. The leptin signaling pathway is recognized to primarily regulate energy balance and associated with breast cancer. Furthermore, the estrogen signaling pathway plays a critical role in breast carcinogenesis. In this review, we discuss how obesity is linked to breast cancer via cross-talk of leptin and estrogen pathways.
Lysine acetylation, first identified in histones, was initially thought to be a posttranslational modification occuring only in eukaryotic cells that controlled gene transcription either via remodeling chromatin or altering the transcriptional machinery. Recent studies, however, have shown that acetylation is a well-conserved metabolic regulatory mechanism that plays critical roles in regulating and coordinating cell metabolism. Acetylation regulates metabolism through controlling gene transcription, altering the metabolic enzymes activity and possibly other functional aspects, of metabolic enzymes. In this review, we provide an overview of the roles and significance of acetylation in metabolic regulation.
All eukaryotes including the yeast contain a lipid storage compartment which is named lipid particle, lipid droplet or oil body. Lipids accumulating in this subcellular fraction serve as a depot of energy and building blocks for membrane lipid synthesis. In the yeast, the major storage lipids are triacylglycerols (TGs) and steryl esters (SEs). An important step in the life cycle of these non-polar lipids is their mobilization from their site of storage and channeling of their degradation components to the appropriate metabolic pathways. A key step in this mobilization process is hydrolysis of TG and SE which is accomplished by lipases and hydrolases. In this review, we describe our recent knowledge of TG lipases from the yeast based on biochemical, molecular biological and cell biological information. We report about recent findings addressing the versatile role of TG lipases in lipid metabolism, and discuss non-polar lipid homeostasis and its newly discovered links to various cell biological processes in the yeast.
In fasting mammals, the liver is the primary source of glucose production for maintenance of normoglycemia. In this setting, circulating peptide hormones and catecholamines cause hepatic glucose output by stimulating glycogen breakdown as well as
Phosphorus (P) is one of the most important major mineral elements for plant growth and metabolism. Plants have evolved adaptive regulatory mechanisms to maintain phosphate (Pi) homeostasis by improving phosphorus uptake, translocation, remobilization and efficiency of use. Here we review recent advances in our understanding of the OsPHR2-mediated phosphate-signaling pathway in rice. OsPHR2 positively regulates the low-affinity Pi transporter
A double lipid bilayer separating the nucleus from the cytoplasm, termed the nuclear envelope, is a defining feature of eukaryotes. Nucleocytoplasmic transport of macromolecules through the nuclear pores enables fine-tuned regulation of biologic processes. All mature mRNAs are delivered to the cytoplasm from the nucleus via an mRNA export pathway. Much work has been done in yeast and animals to study the machinery of mRNA export. However, until recently, research on plant mRNA export has been quite limited. Genetic, bioinformatic, and biochemical investigations have expanded our understanding of the mRNA export process in plants. Here, we review recent progress that has been made elucidating the components of the mRNA export pathway in plants. MOS3 (MODIFIER OF SNC1, 3) /AtNup96 and AtNup160 are both components of the highly conserved Nup107-160 nucleoporin complex and were shown to play key roles in mRNA export. MOS11 (MODIFIER OF SNC1, 11), which is homologous to the RNA helicase enhancer CIP29 in human, was recently found to be involved in the same pathway as MOS3. A DEAD Box RNA helicase, LOS4 (low expression of osmotically responsive genes 4) was also found to play a role in the mRNA export process, putatively by carrying mRNA molecules through the nuclear envelope. Recently, a protein complex homologous to the yeast TREX-2 complex was also found to play important roles in mRNA export in plants. It appears that most players in the mRNA export pathway are highly conserved among plants, yeast and animals.
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain. As one of several types of endogenous receptors, GABAA receptors have been shown to be essential in most, if not all, aspects of brain functioning, including neural development and information processing. Mutations in genes encoding GABAA receptors and alterations in the function of GABAA receptors are associated with many neurologic diseases, and GABAA receptors have been clinically targeted by many drugs, such as benzodiazepines and general anesthetics. Extensive studies have revealed a number of intracellular chaperons/interactions for GABAA receptors, providing a protein–protein network in regulating the trafficking and location of GABAA receptors in the brain. Recently, neurexins and neuroligins, two families of transmembrane proteins present at neurological synapses, are implicated as new partners to GABAA receptors. These works shed new light on the synaptic regulation of GABAA receptor activity. Here, we summarized the proteins that were implicated in the function of GABAA receptors, including neurexins and neuroligins.