Coexpression of phospholipase A2 isoforms in rat striatal astrocytes

Zanassi, Patrizia; Paolillo, Mayra; Schinelli, Sergio

doi:10.1016/s0304-3940(98)00262-6

Cited by 29 publications

(17 citation statements)

References 14 publications

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“…In primary rat astrocytes, cytokines (TNF␣, IL-1␤, and IFN␥) stimulated the increase in prostaglandin E2 (PGE2) production, which was preceded by an increase in cyclooxygenase-2 (COX-2) and sPLA 2 mRNA but not COX-1 and cPLA 2 mRNA (22). In another study in rat astrocytes, LPS also increased expression of sPLA 2 mRNA but not cPLA 2 mRNA (27). Although cytokines did not increase cPLA 2 mRNA levels, an increase in cPLA 2 phosphorylation was observed (22).…”

Section: Response To Inflammatory Agentsmentioning

confidence: 97%

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Phospholipase A2 in the central nervous system

Sun

Xu²,

Jensen

et al. 2004

Journal of Lipid Research

355

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Phospholipase A 2 (PLA 2 ) belongs to a family of enzymes that catalyze the cleavage of fatty acids from the sn-2 position of phospholipids. There are more than 19 different isoforms of PLA 2 in the mammalian system, but recent studies have focused on three major groups, namely, the group IV cytosolic PLA 2 , the group II secretory PLA 2 (sPLA 2 ), and the group VI Ca 2 ؉ -independent PLA 2 . These PLA 2 s are involved in a complex network of signaling pathways that link receptor agonists, oxidative agents, and proinflammatory cytokines to the release of arachidonic acid (AA) and the synthesis of eicosanoids. PLA 2 s acting on membrane phospholipids have been implicated in intracellular membrane trafficking, differentiation, proliferation, and apoptotic processes. All major groups of PLA 2 are present in the central nervous system (CNS). Therefore, this review is focused on PLA 2 and AA release in neural cells, especially in astrocytes and neurons. In addition, because many neurodegenerative diseases are associated with increased oxidative and inflammatory responses, an attempt was made to include studies on PLA 2 in cerebral ischemia, Alzheimer's disease, and neuronal injury due to excitotoxic agents. Information from these studies has provided clear evidence for the important role of PLA 2 in regulating physiological and pathological functions in the CNS. Bazan (1) recognized the important role of arachidonic acid (AA) in the central nervous system (CNS) in the '70s when he observed the rapid and transient release of this fatty acid in the brain due to seizure and cerebral ischemia. The "Bazan effect" has since stimulated over 30 years of investigations attempting to unravel mechanisms regulating AA release from membrane phospholipids in the CNS.Phospholipids in CNS membranes are enriched in polyunsaturated fatty acids (PUFAs) (2). Metabolism of PUFA is stringently controlled by phospholipase A 2 (PLA 2 ) and acyltransferases-known as the "deacylation-reacylation cycle" (3-5). Under normal conditions, free fatty acids (FFAs) released by PLA 2 are rapidly taken up by membrane phospholipids through an energy-dependent process involving CoA and ATP (6). To date, limited information is available on the structure and functions of acyltransferases. However, recent advances in molecular biological techniques have aided in the identification of many genes encoding different groups of PLA 2 and have provided new information on the properties and functions of these molecules.PLA 2 (EC3.1.1.4.) belongs to a family of enzymes that catalyze the cleavage of fatty acids from the sn -2 position of phospholipids. These enzymes are not only important for maintenance of cell membrane phospholipids; they also play a key role in regulating the release of AA, a precursor for synthesis of eicosanoids. In the mammalian system, more than 19 different isoforms of PLA 2 have been identified, and different PLA 2 s have been shown to participate in physiological events related to cell injury, inflammation, and apoptosis (7,8). Re...

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Section: Response To Inflammatory Agentsmentioning

confidence: 97%

“…Astrocytes have been shown to contain all major groups of PLA 2 (27). Therefore, these cells have been used to study the roles of different groups of PLA 2 in normal physiological and pathological functions.…”

Section: Pla 2 In Astrocytesmentioning

confidence: 99%

Phospholipase A2 in the central nervous system

Sun

Xu²,

Jensen

et al. 2004

Journal of Lipid Research

355

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“…PLA 2 s, including iPLA 2 ␤ , are widely expressed in different regions of the brain (289)(290)(291), and iPLA 2 ␤ immunoreactivity has been reported to be predominant in the cytosol and of less abundance in the nuclear fraction ( 292 ), suggesting a role for the enzyme and its products in nuclear signaling. iPLA 2 ␤ has been purifi ed from rat brain cytosol ( 293 ) and identifi ed in dendrites and neurons, microglia, Purkinje cells, and astrocytes ( 290,(294)(295)(296), suggesting that it also participates in neuronal signaling. Advances in lipidomic analyses, coupled with kinetic studies in rodents and positron emission tomography protocols in humans, reveal that the turnover of AA in the brain is associated with cPLA 2 and COX-2 activities, whereas that of DHA (22:6n-3) was related to iPLA 2 ␤ and COX-1 activities ( 297 ).…”

Section: Ipla 2 ␤ and Diseasesmentioning

confidence: 99%

Calcium-independent phospholipases A2 and their roles in biological processes and diseases

Ramanadham

Ali

Ashley

et al. 2015

Journal of Lipid Research

166

190

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The Ca 2+ -independent phospholipases A 2 (iPLA 2 s) are part of a diverse family of PLA 2 s that hydrolyze the sn -2 substituent from membrane phospholipids to release a free fatty acid and a lysolipid ( 1, 2 ). These enzymes are ubiquitously expressed, and in contrast to secretory PLA 2 s (sPLA 2 s) and cytosolic PLA 2 s (cPLA 2 s), do not require Ca 2+ for either translocation or activity. Some of the fi rst descriptions of iPLA 2 activity were in the mid-to late-1980s with the identifi cation of a plasmalogen-selective PLA 2 in Abstract Among the family of phospholipases A 2 (PLA 2 s) are the Ca 2+ -independent PLA 2 s (iPLA 2 s) and they are designated group VI iPLA 2 s. In relation to secretory and cytosolic PLA 2 s, the iPLA 2 s are more recently described and details of their expression and roles in biological functions are rapidly emerging. The iPLA 2 s or patatin-like phospholipases (PNPLAs) are intracellular enzymes that do not require Ca 2+ for activity, and contain lipase (GXSXG) and nucleotide-binding (GXGXXG) consensus sequences. Though nine PNPLAs have been recognized, PNPLA8 (membraneassociated iPLA 2 ␥ ) and PNPLA9 (cytosol-associated iPLA 2 ␤ ) are the most widely studied and understood. The iPLA 2 s manifest a variety of activities in addition to phospholipase, are ubiquitously expressed, and participate in a multitude of biological processes, including fat catabolism, cell differentiation, maintenance of mitochondrial integrity, phospholipid remodeling, cell proliferation, signal transduction, and cell death. As might be expected, increased or decreased expression of iPLA 2 s can have profound effects on the metabolic state, CNS function, cardiovascular performance, and cell survival; therefore, dysregulation of iPLA 2 s can be a critical factor in the development of many diseases. This review is aimed at providing a general framework of the current understanding of the iPLA 2 s and discussion of the potential mechanisms of action of the iPLA 2 s and related involved lipid mediators. -Ramanadham, S

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“…Each class of PLA 2 is further subdivided into isozymes of which there are 14 for sPLA 2 , at least 4 for cPLA 2 , and 2 for iPLA 2 . Genes coding for sPLA 2 , cPLA 2 , and iPLA 2 have been shown to occur in different regions of brain, in neurons, microglia, and astrocytes (Molloy et al, 1998;Zanassi et al, 1998;Balboa et al, 2002). PLA 2 isoforms have been partially purified and characterized from brain tissue (Hirashima et al, 1992;Ross et al, 1995;Yang et al, 1999), but none have been cloned and fully characterized.…”

Section: Multiplicity Of Phospholipases a 2 In Brainmentioning

confidence: 99%