Cellular compartment

About: Cellular compartment is a research topic. Over the lifetime, 1082 publications have been published within this topic receiving 53794 citations. The topic is also known as: cell compartmentation.

Phage Libraries for Generation of Single Chain Fv Antibodies for Intracellular Immunization

Abstract: Antibodies are heterodimers that specifically bind to a target molecule (anti-gen). Their ability to interfere with antigen function or synthesis make them useful tools for the in situ analysis of intracellular molecules. Antibodies can be directly introduced into the cell or they can be expressed from their genes in a specific cellular compartment where they will bind their target. The introduction of antibodies intracellularly was first successfully achieved by micro injection (in the cytoplasm or in the nucleus)1 or more recently, by electroporation.2 The specific (but transient) effects that were obtained by these methods opened the way to a large number of applications. Expression was also obtained by injection of poly A+ mRNA purified from a hybridoma secreting an antibody of interest in xenopus oocytes.3 For example, an anti-golgi protein antibody mRNA was able to inhibit the intracellular trafficking of a viral protein.4 These experiments showed clearly that a specific antibody/antigen interaction was possible in eukaryotic cells.

Prohibitin Deficiency Causes Opposing Lipid Metabolism between 3T3-L1 Adipocytes and Clone 9 Hepatocytes

Abstract: Prohibitin (PHB) is a highly conserved protein in eukaryotic cells that are present in multiple cellular compartments and has potential roles as a tumor suppressor, an anti-proliferative protein, a regulator of cell-cycle progression and in apoptosis. In the present study, we generated PHB-deficient 3T3-L1 adipocytes and Clone 9 (C9) hepatocytes by oligonucleotide siRNA and investigated whether PHB affect lipid metabolism. It was revealed that PHB deficiency caused opposing lipid metabolism between the two cell models. PHB deficiency increased expression of adipogenic, lipogenic, and other lipid metabolic proteins in 3T3-L1 adipocytes, whereas significantly decreased the levels of those proteins in C9 cells. Collectively, PHB deficiency promoted lipid metabolism in 3T3-L1 adipocytes while it aggravated lipid metabolism in C9 hepatocytes.

Biochemical evidence for energy-independent flippase activity in bovine epididymal sperm membranes: an insight into membrane biogenesis

Abstract: During the maturation process spermatozoa undergo a series of changes in their lateral and horizontal lipid profiles. However, lipid metabolism in spermatozoa is not clearly understood for two reasons: i) the mature spermatozoa are devoid of endoplasmic reticulum, which is the major site of phospholipid (PL) synthesis in somatic cells, and ii) studies have been superficial due to the difficulty in culturing spermatozoa. We hypothesize that spermatozoa contain biogenic membrane flippases since immense changes in lipids occur during spermatogenic differentiation. To test this, we isolated spermatozoa from bovine epididymides and reconstituted the detergent extract of sperm membranes into proteoliposomes. In vitro assays showed that proteoliposomes reconstituted with sperm membrane proteins exhibit ATP-independent flip-flop movement of phosphatidylcholine (PC), phosphatidylserine, and phosphatidylglycerol. Half-life time of PC flipping was found to be ∼3.2±1 min for whole sperm membrane, which otherwise would have taken ∼11-12 h in the absence of protein. Further biochemical studies confirm the flip-flop movement to be protein-mediated, based on its sensitivity to protease and protein-modifying reagents. To further determine the cellular localization of flippases, we isolated mitochondria of spermatozoa and checked for ATP-independent flippase activity. Interestingly, mitochondrial membranes showed flip-flop movement but were specific for PC with half-life time of ∼5±2 min. Our results also suggest that spermatozoa have different populations of flippases and that their localization within the cellular compartments depends on the type of PL synthesis.

Osmotic cell swelling alkalinizes acidic cellular compartments of pancreatic islet and RINm5F cells.

Abstract: To the Editor: Recent studies in liver cells have demonstrated that the pH of acidic intracellular compartments in various cell types is highly sensitive to cell volume, i.e., cell swelling leads to an alkalinization of the acidic cellular compartments (1-3). Hepatic proteolysis resides largely within acidic lysosomes and is accomplished by pH-sensitive lysosomal proteinases (4). Thus, the alkalinization of acidic intracellular compartments could couple cell volume to proteolysis, which has been shown to be inhibited by cell swelling (1). The present experiments were performed to test whether cell volume similarly influences the pH of acidic intracellular compartments in endocrine cells, such as cells from pancreatic islets. To this end, acridine orange and fluorescein isothiocyanate (F1TC)-dextran have been utilized as fluorescent indicators of pH in intracellular acidic compartments.