Beta-adrenergic stimulation of fatty acid release from brown fat cells differentiated in monolayer culture

The ability of brown adipocytes differentiated in monolayer culture to respond to norepinephrine was investigated. It was found that fatty acid release in confluent brown adipocytes in monolayer culture was induced by norepinephrine, thus these cells were hormone-sensitive. After confluence, the rate of fatty acid release successively declined. The norepinephrine-stimulated fatty acid release was inhibited by propranolol, but not by phentolamine, indicating a mediation via beta-adrenergic receptors. It was concluded that there exist in the brown adipose tissue of nonfetal rats preadipocytes which possess the ability to express in culture a fully developed beta-adrenergic lipolytic response.     

Cellular control of connective tissue matrix tension

The biomechanical behavior of connective tissue in response to stretching is generally attributed to the molecular composition and organization of its extracellular matrix. It also is becoming apparent that fibroblasts play an active role in regulating connective tissue tension. In response to static stretching of the tissue, fibroblasts expand within minutes by actively remodeling their cytoskeleton. This dynamic change in fibroblast shape contributes to the drop in tissue tension that occurs during viscoelastic relaxation. We propose that this response of fibroblasts plays a role in regulating extracellular fluid flow into the tissue, and protects against swelling when the matrix is stretched. This article reviews the evidence supporting possible mechanisms underlying this response including autocrine purinergic signaling. We also discuss fibroblast regulation of connective tissue tension with respect to lymphatic flow, immune function, and cancer. J. Cell. Biochem. 114: 1714–1719, 2013. © 2013 Wiley Periodicals, Inc.     

Astroglial cradle in the life of the synapse

Astroglial perisynaptic sheath covers the majority of synapses in the central nervous system. This glial coverage evolved as a part of the synaptic structure in which elements directly responsible for neurotransmission (exocytotic machinery and appropriate receptors) concentrate in neuronal membranes, whereas multiple molecules imperative for homeostatic maintenance of the synapse (transporters for neurotransmitters, ions, amino acids, etc.) are shifted to glial membranes that have substantially larger surface area. The astrocytic perisynaptic processes act as an ‘astroglial cradle’ essential for synaptogenesis, maturation, isolation and maintenance of synapses, representing the fundamental mechanism contributing to synaptic connectivity, synaptic plasticity and information processing in the nervous system.     

A sequence predicted to form a stem–loop is proposed to be required for formation of an RNA–protein complex involving the 3'UTR of β-subunit F0F1-ATPase mRNA

ATP-synthase assembly requires coordinated control of ATP mRNA translation; this may e.g. occur through the formation of mRNA–protein complexes. In this study we aim to identify sequences in the 3'UTR of the β-subunit F₁-ATPase mRNA necessary for RNA–protein complex formation. We examined the interaction between a brain cytoplasmic protein extract and in vitro-synthesized β-subunit 3'UTR probes containing successive accumulative 5'- and 3'-deletions, as well as single subregion deletions, with or without poly(A) tail. Using electrophoretic mobility shift assays we found that two major RNA–protein complexes (here called RPC1 and RPC2) were formed with the full-length 3'UTR. The RPC2 complex formation was fully dependent on the presence of both the poly(A) tail and one subregion directly adjacent to it. For RPC1 complex formation, a 3'UTR sequence stretch (experimentally divided into three subregions) adjacent to but not including the poly(A) tail was necessary. This sequence stretch includes a conserved 40-nucleotide region that, according to the structure prediction program mfold, is able to fold into a characteristic stem–loop structure. Since the formation of the RPC1 complex was not dependent on a conventional sequence motif in the 3'UTR of the β-subunit mRNA but rather on the presence of the predicted stem–loop-forming region as such, we hypothetize that this RNA region, by forming a stem–loop in the 3'UTR β-subunit mRNA, is necessary for formation of the RNA–protein complex.     

Lipid molecular timeline profiling reveals diurnal crosstalk between the liver and circulation

1. Download : Download high-res image (168KB)
2. Download : Download full-size image