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.

Crosstalk between cellular compartments protects against proteotoxicity and extends lifespan

Abstract: In cells living under optimal conditions, protein folding defects are usually prevented by the action of chaperones. Here, we investigate the cell-wide consequences of loss of chaperone function in cytosol, mitochondria or the endoplasmic reticulum (ER) in budding yeast. We find that the decline in chaperone activity in each compartment results in loss of respiration, demonstrating the dependence of mitochondrial activity on cell-wide proteostasis. Furthermore, each chaperone deficiency triggers a response, presumably via the communication among the folding environments of distinct cellular compartments, termed here the cross-organelle stress response (CORE). The proposed CORE pathway encompasses activation of protein conformational maintenance machineries, antioxidant enzymes, and metabolic changes simultaneously in the cytosol, mitochondria, and the ER. CORE induction extends replicative and chronological lifespan in budding yeast, highlighting its protective role against moderate proteotoxicity and its consequences such as the decline in respiration. Our findings accentuate that organelles do not function in isolation, but are integrated in a functional crosstalk, while also highlighting the importance of organelle communication in aging and age-related diseases.

Discovery of Cell Compartment Specific Protein–Protein Interactions using Affinity Purification Combined with Tandem Mass Spectrometry

Abstract: Affinity purification combined with tandem mass spectrometry (AP-MS/MS) is a well-established method used to discover interaction partners for a given protein of interest. Because most AP-MS/MS approaches are performed using the soluble fraction of whole cell extracts (WCE), information about the cellular compartments where the interactions occur is lost. More importantly, classical AP-MS/MS often fails to identify interactions that take place in the nonsoluble fraction of the cell, for example, on the chromatin or membranes; consequently, protein complexes that are less soluble are underrepresented. In this paper, we introduce a method called multiple cell compartment AP-MS/MS (MCC-AP-MS/MS), which identifies the interactions of a protein independently in three fractions of the cell: the cytoplasm, the nucleoplasm, and the chromatin. We show that this fractionation improves the sensitivity of the method when compared to the classical affinity purification procedure using soluble WCE while keeping a very high specificity. Using three proteins known to localize in various cell compartments as baits, the CDK9 subunit of transcription elongation factor P-TEFb, the RNA polymerase II (RNAP II)-associated protein 4 (RPAP4), and the largest subunit of RNAP II, POLR2A, we show that MCC-AP-MS/MS reproducibly yields fraction-specific interactions. Finally, we demonstrate that this improvement in sensitivity leads to the discovery of novel interactions of RNAP II carboxyl-terminal domain (CTD) interacting domain (CID) proteins with POLR2A.

Molecular Cell Biology: Are Reactive Oxygen Species Regulators of Leaf Senescence?

Abstract: Senescence processes can influence many important agricultural traits; however, our knowledge concerning regulatory mechanisms controlling senescence is still limited. Free radicals are thought to play an essential role in senescence, especially those derived from oxygen. In addition to their deleterious functions, they might serve as signalling molecules. The critical balance between production and scavenging of reactive oxygen species (ROS), which normally is very tightly regulated, appears to be specifically disrupted during the progression of senescence in different cellular compartments either by depletion of antioxidants or excess production of ROS. Hydrogen peroxide (H 2 O 2 ) is very likely the most important ROS. In contrast to other ROS, it has a relatively long half-life and can also pass membranes; therefore, it can be assumed that it executes signalling functions. Hydrogen peroxide is produced in different cell compartments but can also be released into the cytosol or vice versa. The role of ROS originating from different cellular compartments like chloroplasts, peroxisomes or mitochandria is discussed here with respect to senescence.