Characterization of Motor Neuron Prostaglandin E2 EP3 Receptor Isoform in a Mouse Model of Amyotrophic Lateral Sclerosis

Abstract

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease with adult onset, characterized by progressive loss of motor neurons. Prostaglandin E2 (PGE2), a lipid mediator, exerts its biological functions by binding to four subtypes of E-prostanoid (EP1-4). Among them, EP3 has been shown to have multiple isoforms, EP3α, EP3β, and EP3γ, produced by alternative splicing. Since PGE2 has been shown to have important pathophysiological roles in ALS, experiments were performed to identify EP3 receptor isoform(s) in spinal motor neurons of wild-type (WT) and ALS model (G93A) mice. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of adult mice demonstrated expression of EP3α and EP3γ mRNAs in the lumbar spinal cord, whereas EP3β mRNA was barely detectable. Laser capture microdissection was used to dissect out motor neurons from frozen samples of lumbar spinal cord in these mice for analysis by real-time PCR. We found that expression of EP3γ mRNA was predominant in these neurons, whereas EP3α and EP3β mRNAs were undetectable. At the early symptomatic stage, the mRNA expression profiles of these splice isoforms in G93A motor neurons were comparable to those in neurons from WT mice. These results suggest that the PGE2-to-EP3 signaling pathway is mediated mainly by the EP3γ isoform in the motor neurons of mice, and that modulation of the EP3γ isoform in motor neurons may be a promising new therapeutic approach for ALS.Key words motor neuron; prostaglandin E2 (PGE2); E-prostanoid 3 (EP3) receptor isoform; amyotrophic lateral sclerosis; laser microdissection Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disease characterized by selective loss of motor neurons in the cortex and spinal cord. ALS causes progressive muscular paralysis reflecting the degeneration of motor neurons, a poor quality of life, and eventual death within 3-5 years of diagnosis. 1) Although multiple processes are thought to be implicated in the pathogenesis of ALS, including oxidative stress, mitochondrial dysfunction, excitotoxicity, RNA-processing errors and abnormal protein aggregation, 2) the mechanism underlying the selective death of motor neurons has not yet been clarified. Recently, inflammation in the spinal cord has been highlighted as an important pathogenic mechanism in ALS, and levels of prostaglandin E2 (PGE2), a key proinflammatory mediator, are increased in postmortem brain tissue, cerebrospinal fluid and serum from patients with sporadic ALS.3,4) It has also been shown that ALS model mice have markedly increased levels of PGE2 in both the cerebral cortex and spinal cord. 5) Moreover, the expression of cyclooxygenase (COX)-2, which plays a key role in the synthesis of prostaglandins from arachidonic acid, is up-regulated in the spinal cord of ALS patients and model mice.6,7) Treatment with celecoxib, a selective COX-2 inhibitor, delays the onset of the disease and prolongs survival.8) Recently, we have also shown that the level of microsomal PGE synthase-1 (mPGES-1), catalyzing the ter...

Generation of Cellular Reactive Oxygen Species by Activation of the EP2 Receptor Contributes to Prostaglandin E2-Induced Cytotoxicity in Motor Neuron-Like NSC-34 Cells

“…Oxidative Medicine and Cellular Longevity EP3α, EP3β, and EP3γ [28]. Previously, we have confirmed that EP3γ is the major expression isoform in the motor neurons of mice [26]. As is the case for the mRNA profile in mouse motor neurons, the present study showed that EP3γ is dominantly expressed in differentiated NSC-34 cells.…”

“…In contrast, the level of intracellular ROS after treatment with 40 μM sulprostone, an EP1/EP3 agonist, was transiently but significantly decreased after incubation for 120 to 180 min (Figure 1(a)). Moreover, DCF analysis showed that the generation of ROS caused by PGE2 at 80 μM was attenuated significantly in the presence of PF-04418948, an EP2-selective antagonist, at 30 μM (Figure 1 Mouse EP3 has three different isoforms (EP3α, EP3β, and EP3γ), and we have previously shown that expression of EP3γ mRNA is predominant in mouse motor neurons, whereas EP3α and EP3β are not detectable [26]. Therefore, we sought to identify the distribution of EP3 receptor isoforms in differentiated NSC-34 cells.…”

Alterations in the stomatognathic system due to amyotrophic lateral sclerosis

“…In ALS, muscle spasms are continuous and do not alter during voluntary movements 17 . These rapid, spontaneous, and intermittent contractions of muscle fibers are called fasciculation 4 .…”

Prostaglandin E2 promotes human CD34+ cells homing through EP2 and EP4 in vitro

“…Different receptors mediated different physiological effects, and their expression levels varied between different tissues and organs. Aside from promoting human CD34 + cell homing, PGE2 may also induce other biological effects through other sub-receptors (28–34). Thus, the promoting effect of PGE2 on human CD34 + cells is nonspecific, and its direct application to patients may result in serious side effects.…”