Transplanting cells from old but not young donors causes physical dysfunction in older recipients.

Adipose-derived mesenchymal stem cell (ADSC)-based regenerative therapies have shown potential for use in many chronic diseases. Aging diminishes stem cell regenerative potential, yet it is unknown whether stem cells from aged donors cause adverse effects in recipients. ADSCs can be obtained using minimally invasive approaches and possess low immunogenicity. Nevertheless, we found that transplanting ADSCs from old donors, but not those from young donors, induces physical dysfunction in older recipient mice. Using single-cell transcriptomic analysis, we identified a naturally occurring senescent cell-like population in ADSCs primarily from old donors that resembles in vitro-generated senescent cells with regard to a number of key pathways. Our study reveals a previously unrecognized health concern due to ADSCs from old donors and lays the foundation for a new avenue of research to devise interventions to reduce harmful effects of ADSCs from old donors.

Treating Cocaine Addiction, Obesity, and Emotional Disorders by Viral Gene Transfer of Butyrylcholinesterase.

Butyrylcholinesterase (BChE), a plasma enzyme that hydrolyses the neurotransmitter, acetylcholine relatively well, with far lower efficiency than acetylcholinesterase (AChE) but with the capability to degrade a broad range of bioactive esters. AChE is universally understood as essential to cholinergic neurotransmission, voluntary muscle performance, and cognition, among other roles, and its catalytic impact is essential for life. A total absence of BChE activity, whether by enzyme inhibition or simple lack of enzyme protein is not only compatible with life, but does not lead to obvious physiologic disturbance. However, very recent studies at Mayo Clinic have amassed support for the concept that BChE does have a true physiological role as a "ghrelin hydrolase" and, pharmacologically, as a cocaine hydrolase. Human subjects and animal mutations that lack functional BChE show higher than normal levels of ghrelin, an acylated peptide that drives hunger and feeding, along with certain emotional behaviors. Mice treated by viral gene transfer of BChE show higher plasma levels of enzyme and lower levels of ghrelin. Ghrelin is acknowledged as a driver of food-seeking and stress. This brief review examines some key phenomena and considers means of modulating BChE as treatments for cocaine addiction, anxiety, aggression, and obesity.

Characterization of acetylcholinesterase in Hong Kong oyster (Crassostrea hongkongensis) from South China Sea.

Acetylcholinesterase (AChE) activity has been used to evaluate the exposure of mollusk bivalves to organophosphates, carbamate pesticides, and heavy metals. Crassostrea hongkongensis is a Hong Kong endemic oyster, and has a high commercial value along the coastal area of South China. The use of this species as a bio-indicator of the marine environment, and the use of AChE activity measurements in tissues of C. hongkongensis require prior characterization of AChE in this species. Here, we report that gill tissue contains the highest AChE activity in C. hongkongensis, and that the molecular form of AChE is most likely to be a dimeric form. In addition, the effect of the pesticide acephate on AChE activity in the gill of C. hongkongensis was analyzed, and the mean inhibition concentration (IC50) value was determined. This study suggests that AChE activity in the gill tissue of C. hongkongensis might be used as a biomarker in monitoring organophosphate contamination in the marine fauna of South China.

Expression of cAMP-responsive element binding proteins (CREBs) in fast- and slow-twitch muscles: a signaling pathway to account for the synaptic expression of collagen-tailed subunit (ColQ) of acetylcholinesterase at the rat neuromuscular junction.

The gene encoding the collagen-tailed subunit (ColQ) of acetylcholinesterase (AChE) contains two distinct promoters that drive the production of two ColQ mRNAs, ColQ-1 and ColQ-1a, in slow- and fast-twitch muscles, respectively. ColQ-1a is expressed at the neuromuscular junction (NMJ) in fast-twitch muscle, and this expression depends on trophic factors supplied by motor neurons signaling via a cAMP-dependent pathway in muscle. To further elucidate the molecular basis of ColQ-1a's synaptic expression, here we investigated the expression and localization of cAMP-responsive element binding protein (CREB) at the synaptic and extra-synaptic regions of fast- and slow-twitch muscles from adult rats. The total amount of active, phosphorylated CREB (P-CREB) present in slow-twitch soleus muscle was higher than that in fast-twitch tibialis muscle, but P-CREB was predominantly expressed in the fast-twitch muscle at NMJs. In contrast, P-CREB was detected in both synaptic and extra-synaptic regions of slow-twitch muscle. These results reveal, for the first time, the differential distribution of P-CREB in fast- and slow-twitch muscles, which might support the crucial role of cAMP-dependent signaling in controlling the synapse-specific expression of ColQ-1a in fast-twitch muscles.

N-linked glycosylation of dimeric acetylcholinesterase in erythrocytes is essential for enzyme maturation and membrane targeting.

Acetylcholinesterase (AChE) is well-known for its cholinergic functions in the nervous system; however, this enzyme is also found in other tissues where its function is still not understood. AChE is synthesized through alternative splicing as splicing variants, with isoforms including read-through (AChE(R)), tailed (AChE(T)) and hydrophobic (AChE(H)). In human erythrocytes, AChE(H) is a glycophosphatidylinositol-linked dimer on the plasma membrane. Three N-linked glycosylation sites have been identified in the catalytic domain of human AChE. Here, we investigate the roles of glycosylation in assembly and trafficking of human AChE(H). In transfected fibroblasts, expression of AChE(H) was able to mimic the function of the dimeric form of AChE on the erythrocyte membrane. A glycan-depleted form was constructed by site-directed mutagenesis. By comparison with the wild-type AChE(H), the mutant had a much lower enzymatic activity and a much higher K(m) value. In addition, the mutant was dimerized in the endoplasmic reticulum, but was not trafficked to the Golgi apparatus. The results suggest that the glycosylation may affect AChE(H) enzymatic activity and trafficking, but not dimer formation. The present findings indicate the significance of N-glycosylation in controlling the biosynthesis of the AChE(H) dimer form.

N-linked glycosylation of proline-rich membrane anchor (PRiMA) is not required for assembly and trafficking of globular tetrameric acetylcholinesterase.

Acetylcholinesterase (AChE) is organized into globular tetramers (G(4)) by a structural protein called proline-rich membrane anchor (PRiMA), anchoring it into the cell membrane of neurons in the brain. The assembly of AChE tetramers with PRiMA requires the presence of a C-terminal "t-peptide" in the AChE catalytic subunit (AChE(T)). The glycosylation of AChE(T) is known to be required for its proper assembly and trafficking; however, the role of PRiMA glycosylation in the oligomer assembly has not been revealed. PRiMA is a glycoprotein containing two putative N-linked glycosylation sites. By using site-directed mutagenesis, the asparagine-43 was identified to be the N-linked glycosylation site of PRiMA. Abolishing glycosylation on mouse PRiMA appeared not to affect its assembly with AChE(T), the enzymatic properties of AChE, and the membrane trafficking of PRiMA-linked AChE tetramers. This result is contrary to the reports that glycosylation is essential for conformation and trafficking of membrane glycoproteins.

Fo shou san, an ancient herbal decoction prepared from angelicae sinensis radix and chuanxiong rhizoma, induces erythropoietin expression: a signaling mediated by the reduced degradation of hypoxia-inducible factor in cultured liver cells.

Fo Shou San (FSS) is an ancient herbal decoction composed of Angelicae Sinensis Radix (ASR; Danggui) and Chuanxiong Rhizoma (CR; Chuanxiong) in a ratio of 3:2. FSS is mainly prescribed for patients having a deficiency of blood supply, and it indeed has been shown to stimulate the production of erythropoietin (EPO) in cultured cells. In order to reveal the mechanism of this FSS-induced EPO gene expression, the upstream regulatory cascade, via hypoxia-induced signaling, was revealed here in cultured hepatocellular carcinoma cell line Hep3B. The induction of EPO gene expression, triggered by FSS, was revealed in cultured hepatocytes by: (i) the increase of EPO mRNA; and (ii) the activation of the hypoxia response element (HRE), an upstream regulator of the EPO gene. The FSS-induced EPO gene expression was triggered by an increased expression of hypoxia-inducible factor-1 α (HIF-1 α) protein; however, the mRNA expression of HIF-1 α was not altered by the treatment of FSS. The increased HIF-1 α was a result of reduced protein degradation after the FSS treatment. The current results therefore provide one of the molecular mechanisms of this ancient herbal decoction for its hematopoietic function.

Molecular Assembly and Biosynthesis of Acetylcholinesterase in Brain and Muscle: the Roles of t-peptide, FHB Domain, and N-linked Glycosylation.

Acetylcholinesterase (AChE) is responsible for the hydrolysis of the neurotransmitter, acetylcholine, in the nervous system. The functional localization and oligomerization of AChE T variant are depending primarily on the association of their anchoring partners, either collagen tail (ColQ) or proline-rich membrane anchor (PRiMA). Complexes with ColQ represent the asymmetric forms (A(12)) in muscle, while complexes with PRiMA represent tetrameric globular forms (G(4)) mainly found in brain and muscle. Apart from these traditional molecular forms, a ColQ-linked asymmetric form and a PRiMA-linked globular form of hybrid cholinesterases (ChEs), having both AChE and BChE catalytic subunits, were revealed in chicken brain and muscle. The similarity of various molecular forms of AChE and BChE raises interesting question regarding to their possible relationship in enzyme assembly and localization. The focus of this review is to provide current findings about the biosynthesis of different forms of ChEs together with their anchoring proteins.

The assembly of proline-rich membrane anchor (PRiMA)-linked acetylcholinesterase enzyme: glycosylation is required for enzymatic activity but not for oligomerization.

Acetylcholinesterase (AChE) anchors onto cell membranes by a transmembrane protein PRiMA (proline-rich membrane anchor) as a tetrameric form in vertebrate brain. The assembly of AChE tetramer with PRiMA requires the C-terminal "t-peptide" in AChE catalytic subunit (AChE(T)). Although mature AChE is well known N-glycosylated, the role of glycosylation in forming the physiologically active PRiMA-linked AChE tetramer has not been studied. Here, several lines of evidence indicate that the N-linked glycosylation of AChE(T) plays a major role for acquisition of AChE full enzymatic activity but does not affect its oligomerization. The expression of the AChE(T) mutant, in which all N-glycosylation sites were deleted, together with PRiMA in HEK293T cells produced a glycan-depleted PRiMA-linked AChE tetramer but with a much higher K(m) value as compared with the wild type. This glycan-depleted enzyme was assembled in endoplasmic reticulum but was not transported to Golgi apparatus or plasma membrane.

Baicalin, a flavone, induces the differentiation of cultured osteoblasts: an action via the Wnt/beta-catenin signaling pathway.

Flavonoids, a group of natural compounds found in a variety of vegetables and herbal medicines, have been intensively reported on regarding their estrogen-like activities and particularly their ability to affect bone metabolism. Here, different subclasses of flavonoids were screened for their osteogenic properties by measuring alkaline phosphatase activity in cultured rat osteoblasts. The flavone baicalin derived mainly from the roots of Scutellaria baicalensis showed the strongest induction of alkaline phosphatase activity. In cultured osteoblasts, application of baicalin increased significantly the osteoblastic mineralization and the levels of mRNAs encoding the bone differentiation markers, including osteonectin, osteocalcin, and collagen type 1α1. Interestingly, the osteogenic effect of baicalin was not mediated by its estrogenic activity. In contrast, baicalin promoted osteoblastic differentiation via the activation of the Wnt/ß-catenin signaling pathway; the activation resulted in the phosphorylation of glycogen synthase kinase 3ß and, subsequently, induced the nuclear accumulation of the ß-catenin, leading to the transcription activation of Wnt-targeted genes for osteogenesis. The baicalin-induced osteogenic effects were fully abolished by DKK-1, a blocker of Wnt/ß-catenin receptor. Moreover, baicalin also enhanced the mRNA expression of osteoprotegerin, which could regulate indirectly the activation of osteoclasts. Taken together, our results suggested that baicalin could act via Wnt/ß-catenin signaling to promote osteoblastic differentiation. The osteogenic flavonoids could be very useful in finding potential drugs, or food supplements, for treating post-menopausal osteoporosis.

The expression of erythropoietin triggered by danggui buxue tang, a Chinese herbal decoction prepared from radix Astragali and radix Angelicae Sinensis, is mediated by the hypoxia-inducible factor in cultured HEK293T cells.

ETHNOPHARMACOLOGICAL EVIDENCE: Danggui buxue tang (DBT), a Chinese medicinal decoction that is being commonly used as hematopoietic medicine to treating woman menopausal irregularity, contains two herbs: radix Astragali and radix Angelicae Sinensis. Pharmacological results indicate that DBT can stimulate the production of erythropoietin (EPO), a specific hematopoietic growth factor, in cultured cells. AIM OF THE STUDY: In order to reveal the mechanism of DBT's hematopoietic function, this study investigated the activity of the DBT-induced EPO expression and the upstream regulatory cascade of EPO via hypoxia-induced signaling in cultured kidney fibroblasts (HEK293T). MATERIALS AND METHODS: DBT-induced mRNA expressions were revealed by real-time PCR, while the change of protein expressions were analyzed by Western blotting. For the analysis of hypoxia-dependent signaling, a luciferase reporter was used to report the transcriptional activity of hypoxia response element (HRE). RESULTS: The plasmid containing HRE, being transfected into HEK293T, was highly responsive to the challenge of DBT application. To account for the transcriptional activation of HRE, DBT treatment was shown to increase the mRNA and protein expressions of hypoxia-inducible factor-1α (HIF-1α). In addition, the activation of Raf/MEK/ERK signaling pathway by DBT could also enhance the translation of HIF-1α, suggesting the dual actions of DBT in stimulating the EPO expression in kidney cells. CONCLUSION: Our study indicates that HIF pathway plays an essential role in directing DBT-induced EPO expression in kidney. These results provide one of the molecular mechanisms of this ancient herbal decoction for its hematopoietic function.

The PRiMA-linked cholinesterase tetramers are assembled from homodimers: hybrid molecules composed of acetylcholinesterase and butyrylcholinesterase dimers are up-regulated during development of chicken brain.

Acetylcholinesterase (AChE) is anchored onto cell membranes by the transmembrane protein PRiMA (proline-rich membrane anchor) as a tetrameric globular form that is prominently expressed in vertebrate brain. In parallel, the PRiMA-linked tetrameric butyrylcholinesterase (BChE) is also found in the brain. A single type of AChE-BChE hybrid tetramer was formed in cell cultures by co-transfection of cDNAs encoding AChE(T) and BChE(T) with proline-rich attachment domain-containing proteins, PRiMA I, PRiMA II, or a fragment of ColQ having a C-terminal GPI addition signal (Q(N-GPI)). Using AChE and BChE mutants, we showed that AChE-BChE hybrids linked with PRiMA or Q(N-GPI) always consist of AChE(T) and BChE(T) homodimers. The dimer formation of AChE(T) and BChE(T) depends on the catalytic domains, and the assembly of tetramers with a proline-rich attachment domain-containing protein requires the presence of C-terminal "t-peptides" in cholinesterase subunits. Our results indicate that PRiMA- or ColQ-linked cholinesterase tetramers are assembled from AChE(T) or BChE(T) homodimers. Moreover, the PRiMA-linked AChE-BChE hybrids occur naturally in chicken brain, and their expression increases during development, suggesting that they might play a role in cholinergic neurotransmission.

PRiMA directs a restricted localization of tetrameric AChE at synapses.

Acetylcholinesterase (AChE), a highly polymorphic enzyme with various splicing variants and molecular isoforms, plays an essential role in the cholinergic neurotransmission by hydrolyzing acetylcholine into choline and acetate. The AChE(T) variant is expressed in the brain and muscle: this subunit forms non-amphiphilic tetramers with a collagen tail (ColQ) as asymmetric AChE (A(12) AChE) in muscle, and amphiphilic tetramers with a proline-rich membrane anchor (PRiMA) as globular AChE (G(4) AChE) in the brain and muscle. During the brain development, the expression of amphiphilic G(4) AChE is up regulated and becomes the predominant form of AChE there. This up-regulation of G(4) AChE can be attributed to the increased expressions of both AChE(T) and PRiMA. A significant portion of this membrane-bound G(4) AChE is localized at the membrane rafts of the cell membranes derived from the brain. This raft association could be directed by PRiMA via its CRAC (cholesterol recognition/interaction amino acid consensus) motif and C-terminus. In cultured cortical neurons and muscles, the PRiMA-linked AChE was clustered and partially co-localized with synaptic proteins. The restricted localizations suggest that the raft association of PRiMA-linked AChE could account for its synaptic localization and function.

A flavonol glycoside, isolated from roots of Panax notoginseng, reduces amyloid-beta-induced neurotoxicity in cultured neurons: signaling transduction and drug development for Alzheimer's disease.

A Radix Notoginseng flavonol glycoside (RNFG), quercetin 3-O-beta-D-xylopyranosyl-beta-D-galactopyranoside, was isolated from roots of Panax notoginseng. Among different biological properties tested, RNFG possessed a strong activity in preventing amyloid-beta (Abeta)-induced cell death. In an in vitro assay, RNFG inhibited the aggregation of Abeta in a dose-dependent manner. Moreover, application of RNFG in cultured cortical neurons, or PC12 cells, reduced the Abeta-induced cell death in time- and dose-dependent manners, with the suppression of Abeta-induced DNA fragmentation and caspase-3 activation. In cultured neurons, the pre-treatment of RNFG abolished the increase of Ca(2+) mobilization triggered by Abeta. The neuroprotective properties of RNFG required a specific sugar attachment within the main chemical backbone because the flavonol backbone by itself did not show any protective effect. In memory impairment experiments using the passive avoidance task, the administration of RNFG reduced brain damage in scopolamine-treated rats. These results therefore reveal a novel function of Radix Notoginseng and its flavonol glycoside that could be very useful in developing food supplements for the prevention, or potential treatment, of Alzheimer's disease.

Targeting acetylcholinesterase to membrane rafts: a function mediated by the proline-rich membrane anchor (PRiMA) in neurons.

In the mammalian brain, acetylcholinesterase (AChE) is anchored in cell membranes by a transmembrane protein PRiMA (proline-rich membrane anchor). We present evidence that at least part of the PRiMA-linked AChE is integrated in membrane microdomains called rafts. A significant proportion of PRiMA-linked AChE tetramers from rat brain was recovered in raft fractions; this proportion was markedly higher at low rather than at high concentrations of cold Triton X-100. The detergent-resistant fraction increased during brain development. In NG108-15 neuroblastoma cells transfected with cDNAs encoding AChE(T) and PRiMA, PRiMA-linked G(4) AChE was found in membrane rafts and showed the same sensitivity to cold Triton X-100 extraction as in the brain. The association of PRiMA-linked AChE with rafts was weaker than that of glycosylphosphatidylinositol-anchored G(2) AChE or G(4) Q(N)-H(C)-linked AChE. It was found to depend on the presence of a cholesterol-binding motif, called CRAC (cholesterol recognition/interaction amino acid consensus), located at the junction of transmembrane and cytoplasmic domains of both PRiMA I and II isoforms. The cytoplasmic domain of PRiMA, which differs between PRiMA I and PRiMA II, appeared to play some role in stabilizing the raft localization of G(4) AChE, because the Triton X-100-resistant fraction was smaller with the shorter PRiMA II isoform than that with the longer PRiMA I isoform.

An induction effect of heat shock on the transcript of globular acetylcholinesterase in NG108-15 cells.

Heat shock response, an induced transcription of a set of genes in response to high temperature, occurs in all organisms. In neurons, the catalytic subunit of acetylcholinesterase (AChE(T)) interacts with proline-rich membrane anchor (PRiMA) to form a globular tetrameric form (G(4) form). In this study, we examined the effects of heat shock on the transcription and protein assembly of AChE(T) in cultured NG108-15 cells. The transcription of AChE(T) was rapidly induced by heat shock at 40 degrees C, reaching a 15-fold increase in 3h and decreasing thereafter. On the other hand, the level of PRiMA mRNA was not affected after the heat shock. In parallel with AChE(T) mRNA, the enzymatic activity of cellular AChE, in terms of G(1) and G(2) forms, was increased after heat shock; however, the PRiMA-linked G(4) remained unchanged. These results suggest that heat shock can induce the expression level of AChE(T) by the regulation of AChE(T) transcripts in NG108-15 cells.

Expression and Localization of PRiMA-linked globular form acetylcholinesterase in vertebrate neuromuscular junctions.

Acetylcholinesterase (AChE) is well known to process different molecular forms via the distinct interacting partners. Proline-rich membrane anchor (PRiMA)-linked tetrameric globular AChE (G4 AChE) is mainly found in the vertebrate brain; however, recent studies from our laboratory have suggested its existence at neuromuscular junctions (nmjs). Both muscle and motor neuron express AChE at the nmjs. In muscle, the expression of PRiMA-linked AChE is down-regulated during myogenic differentiation and by motor neuron innervation. As compared with muscle, spinal cord possessed higher total AChE activity and contained PRiMA-linked AChE forms. The spinal cord expression of this form increased during development. More importantly, PRiMA-linked G4 AChE identified as aggregates localized at nmjs. These findings suggest that the restricted localization of PRiMA-linked G4 AChE at the nmjs could be contributed by the pre-synaptic motor neuron and/or the post-synaptic muscle fiber.

Restricted localization of proline-rich membrane anchor (PRiMA) of globular form acetylcholinesterase at the neuromuscular junctions--contribution and expression from motor neurons.

The expression and localization of the proline-rich membrane anchor (PRiMA), an anchoring protein of tetrameric globular form acetylcholinesterase (G(4) AChE), were studied at vertebrate neuromuscular junctions. Both muscle and motor neuron contributed to this synaptic expression pattern. During the development of rat muscles, the expression of PRiMA and AChE(T) and the enzymatic activity increased dramatically; however, the proportion of G(4) AChE decreased. G(4) AChE in muscle was recognized specifically by a PRiMA antibody, indicating the association of this enzyme with PRiMA. Using western blot and ELISA, both PRiMA protein and PRiMA-linked G(4) AChE were found to be present in large amounts in fast-twitch muscle (e.g. tibialis), but in relatively low abundance in slow-twitch muscle (e.g. soleus). These results indicate that the expression level of PRiMA-linked G(4) AChE depends on muscle fiber type. In parallel, the expression of PRiMA, AChE(T) and G(4) AChE also increased in the spinal cord during development. Such expression in motor neurons contributed to the synaptic localization of G(4) AChE. After denervation, the expression of PRiMA, AChE(T) and G(4) AChE decreased markedly in the spinal cord, and in fast- and slow-twitch muscles.

A new variant of proline-rich membrane anchor (PRiMA) of acetylcholinesterase in chicken: expression in different muscle fiber types.

Proline-rich membrane anchor (PRiMA) is a molecule to organize acetylcholinesterase (AChE) into tetrameric globular form (G(4)) that anchors onto the plasma membrane in brain and muscle. In mammal, PRiMA is encoded by a single gene with two splicing variants, PRiMA I and PRiMA II: PRiMA II is different to PRiMA I by its absence of a C-terminal cytoplasmic domain. The existence of these isoforms has not been revealed in avian specie. By using RT-PCR and bioinformatic analyses, two splicing variants of PRiMA were identified in chicken cerebrum. One variant contains very similar domains as compared to mammalian PRiMA I. The other variant, named as PRiMA II, has a very distinct cytoplasmic C-terminus of having 26 amino acids. Both forms of chicken PRiMA were able to organize the formation of G(4) AChE when that was over expressed together with AChE(T) subunit in cultured cells. The level of PRiMA mRNA, mainly PRiMA I, was higher in slow-twitch muscle than that of in fast-twitch muscle of chicken. This finding suggests that the muscle fiber type-specific expression of G(4) AChE in chicken could be a result of the different expression pattern of PRiMA in fast- and slow-twitch muscles.

Transcriptional regulation of proline-rich membrane anchor (PRiMA) of globular form acetylcholinesterase in neuron: an inductive effect of neuron differentiation.

The transcriptional regulation of proline-rich membrane anchor (PRiMA), an anchoring protein of tetrameric globular form of acetylcholinesterase (G(4) AChE), was revealed in cultured cortical neurons during differentiation. The level of AChE(T) protein, total enzymatic activity and the amount of G(4) AChE were dramatically increased during the neuron differentiation. RT-PCR analyses revealed that the transcript encoding PRiMA was significantly up-regulated in the differentiated neurons. To investigate the transcriptional mechanism on PRiMA regulation, a reporter construct of human PRiMA promoter-tagged luciferase was employed in this study. Upon the neuronal differentiation in cortical neurons, a mitogen-activated protein (MAP) kinase-dependent pathway was stimulated: this signaling cascade was shown to regulate the transcriptional activity of PRiMA. In addition, both PRiMA and AChE(T) transcripts were induced by the over expression of an active mutant of Raf in the cultured neurons. The treatment of a MAP kinase inhibitor (U0126) significantly blocked the expression of PRiMA transcript and promoter-driven luciferase activity as induced by the differentiation of cortical neurons. These results suggested that a MAP kinase signaling pathway served as one of the transcriptional regulators in controlling PRiMA gene expression during the neuronal differentiation process.