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Cardiovascular and related metabolic diseases are significant global health challenges. Glucagon-like peptide 1 (GLP-1) is a brain-gut peptide secreted by the ileal endocrine system and is now an established drug target in type 2 diabetes (T2DM). GLP-1 targeting agents have been shown not only to treat T2DM, but also to exert cardiovascular protective effects by regulating multiple signaling pathways. The mitogen-activated protein kinase (MAPK) pathway, a common signal transduction pathway for transmitting extracellular signals to downstream effector molecules, is involved in regulating diverse cellular physiological processes, including cell proliferation, differentiation, stress, inflammation, functional synchronization, transformation, and apoptosis. The purpose of this review is to highlight the relationship between GLP-1 and cardiovascular disease (CVD) and discuss how GLP-1 exerts cardiovascular protective effects through the MAPK signaling pathway. This review also discusses the future challenges in fully characterizing and evaluating the CVD protective effects of GLP-1 receptor agonists (GLP-1RA) at the cellular and molecular levels. A better understanding of the MAPK signaling pathway that is dysregulated in CVD may aid in the design and development of promising GLP-1RA. Key words: glucagon-like peptide 1, type 2 diabetes, mitogen-activated protein kinase pathway, cardiovascular disease. Les maladies cardiovasculaires et les maladies metaboliques qui y sont liees constituent des defisimportantsen sante dans le monde. Le peptide GLP-1 (glucagon-like peptide-1) est un peptide cerebral et intestinal secrete par les cellules endocrines ileales qui est maintenant une cible medicamenteuse etablie dans le diabete de type 2 (DT2). Les agents ciblant le GLP-1 se sont averes non seulement capables de traiter le DT2, mais aussi d'exercer des effets protecteurs cardiovasculaires en regulant de multiples voies de signalisation. La voie de la MAPK (mitogen-activated protein kinase), une voie de transduction du signal commune pour transmettre des signaux extracellulaires a des molecules effectrices en aval, est impliquee dans la regulation de divers processus physiologiques cellulaires, notamment la proliferation, la differenciation, le stress, l'inflammation, la synchronisation fonctionnelle, la transformation et l'apoptose. L'objectif de cette synthese est de mettre en evidence la relation entre le GLP-1 et les maladies cardiovasculaires (MCV), et de discuter de la facon dont le GLP-1 exerce des effets protecteurs cardiovasculaires par la voie de signalisation de la MAPK. Cette synthese aborde egalement les defis a venir dans la caracterisation et 1'evaluation completes des effets protecteurs contre les MCV d'agonistes du recepteur du GLP-1 (GLP-1RA) au niveau cellulaire et moleculaire. Une meilleure comprehension de la voie de signalisation MAPK qui est dereglee dans les MCV peut aider a la conception et au developpement de GLP-1RA prometteurs. [Traduit par la Redaction] Mots-cles: peptide GLP-1, diabete de type 2, voie de la MAPK, maladies cardiovasculaires., 1. Introduction Cardiovascular disease (CVD) is the leading cause of global mortality and is directly associated with atherosclerosis (AS). AS is characterized by the gradual development of chronic inflammation in [...]

Intestinal stromal cells are known to modulate the propagation and differentiation of intestinal stem cells.sup.1,2. However, the precise cellular and molecular mechanisms by which this diverse stromal cell population maintains tissue homeostasis and repair are poorly understood. Here we describe a subset of intestinal stromal cells, named MAP3K2-regulated intestinal stromal cells (MRISCs), and show that they are the primary cellular source of the WNT agonist R-spondin 1 following intestinal injury in mice. MRISCs, which are epigenetically and transcriptomically distinct from subsets of intestinal stromal cells that have previously been reported.sup.3-6, are strategically localized at the bases of colon crypts, and function to maintain LGR5.sup.+ intestinal stem cells and protect against acute intestinal damage through enhanced R-spondin 1 production. Mechanistically, this MAP3K2 specific function is mediated by a previously unknown reactive oxygen species (ROS)-MAP3K2-ERK5-KLF2 axis to enhance production of R-spondin 1. Our results identify MRISCs as a key component of an intestinal stem cell niche that specifically depends on MAP3K2 to augment WNT signalling for the regeneration of damaged intestine. A subset of intestinal stromal cells that is regulated by the kinase MAP3K2 protects intestinal stem cells against injury by producing the WNT agonist R-spondin 1., Author(s): Ningbo Wu [sup.1] [sup.2] , Hongxiang Sun [sup.1] [sup.2] , Xiaoyun Zhao [sup.1] [sup.2] , Yao Zhang [sup.1] [sup.3] , Jianmei Tan [sup.1] [sup.2] , Yuanyuan Qi [sup.1] , [...]

Vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) exhibit hyperproliferation, enhanced MAP kinase (MAPK) activity, and overexpression of Giα proteins. This study was undertaken to examine whether the overexpression of Giα proteins contributes to the hyperproliferation of VSMC of SHR through MAPK signaling. The hyperproliferation of VSMC from SHR in the absence and presence of angiotensin II was restored towards those in Wistar-Kyoto (WKY) rats levels by pertussis toxin (PT) treatment. In addition, siRNA knockdown of Giα proteins also resulted in the attenuation of hyperproliferation towards control levels. The overexpression of Giα proteins was also inhibited by MAPK and PI3 kinase (PI3K) inhibitors. In addition, the hyperproliferation and enhanced phosphorylation of ERK1/2 and Akt in VSMC from SHR were attenuated towards WKY levels by the inhibitors of MAPK, PI3K, c-Src, and antioxidants, whereas PT was unable to attenuate the enhanced phosphorylation of ERK1/2 and Akt. Furthermore, 8Br-cAMP and forskolin also attenuated the hyperproliferation of VSMC from SHR. These results suggest that the hyperproliferation of VSMC from SHR may be attributed to the enhanced expression of Giα proteins and increased activation of MAPK and PI3 kinase. However, Giα-mediated hyperproliferation may not be mediated through MAPK- and PI3 kinase-dependent pathways and may involve decreased levels of intracellular cAMP. Key words: VSMC proliferation, MAP kinase/PI3 kinase, Gi proteins, oxidative stress, SHR. Chez les SHR (pour spontaneously hypertensive rat), on observe une hyperproliferation des cellules musculaires lisses vasculaires (CMLV) ainsi qu'une augmentation de l'activite de la MAP kinase (MAPK) et une surexpression des proteins Giα. Dans la presente etude, nous avons tente de determiner si la surexpression des proteins Giα contribue a l'hyperproliferation des CMLV chez le rat SHR par l'intermediaire de la voie de signalisation de la MAPK. En utilisant la toxine pertussique (TP) en presence et en absence d'angiotensine II, nous avons retabli l'hyperproliferation des CMLV observee chez les rats SHR vers les niveaux observes chez les rats Wistar-Kyoto (WKY). De plus, le silencage des proteins Giα par siRNA a aussi permis d'attenuer l'hyperproliferation vers des niveaux que l'on retrouvait chez les temoins. La surexpression des proteins Giα a aussi ete entravee par les inhibiteurs de la MAPK et du PI3 kinase (PI3K). En outre, les inhibiteurs de la MAPK, du PI3K, et de c-Src ainsi que les antioxydants permettaient d'attenuer l'hyperproliferation et l'accroissement de la phosphorylation d'ERK1/2 et d'Akt dans les CMLV des rats SHR, alors que la TP ne permettait pas d'attenuer l'accroissement de la phosphorylation d'ERK1/2 et d'Akt. Par ailleurs, le 8Br-cAMP et la forskoline ont aussi permis d'attenuer l'hyperproliferation des CMLV chez le rat SHR. Ces resultats laissent entendre que l'hyperproliferation des CMLV chez le rat SHR pourrait etre attribuable a l'expression accrue des proteins Giα et d'une augmentation de l'activation de la MAPK ou de la PI3K. Toutefois, les mecanismes a l'origine de l'hyperproliferation reliee aux proteins Giα pourraient ne pas emprunter les voies de signalisation dependant de la MAPK et de la PI3K, mais plutot passer par la diminution des concentrations intracellulaires d'AMPc. [Traduit par la Redaction] Mots-cles: proliferation des CMLV, MAP kinase/PI3 kinase, proteines Gi, stress oxydatif, rat SHR., Introduction Guanine nucleotide-binding regulatory proteins (G proteins), a family of GTP-binding proteins, play an important role in the regulation of a variety of physiological functions, including blood pressure, through the [...]

Cell migration is a stepwise process that coordinates multiple molecular machineries. Using in vitro angiogenesis screens with short interfering RNA and chemical inhibitors, we define here a MAP4K4-moesin-talin-β1-integrin molecular pathway that promotes efficient plasma membrane retraction during endothelial cell migration. Loss of MAP4K4 decreased membrane dynamics, slowed endothelial cell migration, and impaired angiogenesis in vitro and in vivo. In migrating endothelial cells, MAP4K4 phosphorylates moesin in retracting membranes at sites of focal adhesion disassembly. Epistasis analyses indicated that moesin functions downstream of MAP4K4 to inactivate integrin by competing with talin for binding to β1-integrin intracellular domain. Consequently, loss of moesin (encoded by the MSN gene) or MAP4K4 reduced adhesion disassembly rate in endothelial cells. Additionally, α5β1-integrin blockade reversed the membrane retraction defects associated with loss of Map4k4 in vitro and in vivo. Our study uncovers a novel aspect of endothelial cell migration. Finally, loss of MAP4K4 function suppressed pathological angiogenesis in disease models, identifying MAP4K4 as a potential therapeutic target., Cell migration relies on coordinated engagement and disengagement of cell-extracellular matrix interactions (1). Integrin receptors bind extracellular matrix ligands and orchestrate cytoskeletal and signalling changes (2). The affinity of integrins [...]

Plants must coordinate the regulation of biochemistry and anatomy to optimize photosynthesis and water-use efficiency. The formation of stomata, epidermal pores that facilitate gas exchange, is highly coordinated with other aspects of photosynthetic development. The signalling pathways controlling stomata development are not fully understood (1,2), although mitogen-activated protein kinase (MAPK) signalling is known to have key roles. Here we demonstrate in Arabidopsis that brassinosteroid regulates stomatal development by activating the MAPK kinase kinase (MAPKKK) YDA (also known as YODA). Genetic analyses indicate that receptor kinase-mediated brassinosteroid signalling inhibits stomatal development through the glycogen synthase kinase 3 (GSK3)-like kinase BIN2, and BIN2 acts upstream of YDA but downstream of the ERECTA family of receptor kinases. Complementary in vitro and in vivo assays show that BIN2 phosphorylates YDA to inhibit YDA phosphorylation of its substrate MKK4, and that activities of downstream MAPKs are reduced in brassinosteroid-deficient mutants but increased by treatment with either brassinosteroid or GSK3-kinase inhibitor. Our results indicate that brassinosteroid inhibits stomatal development by alleviating GSK3-mediated inhibition of this MAPK module, providing two key links; that of a plant MAPKKK to its upstream regulators and of brassinosteroid to a specific developmental output., In animals and plants, steroid hormones have important roles in coordinating development and metabolism (3). In contrast to animal steroid hormones, which act through nuclear receptor transcription factors (3), the [...]

Glucocorticoids (GC) are steroid hormones that modulate T cell functions and restrain their hyperresponsiveness following stimulation. Naive T lymphocytes are sensitive to GC but become more resistant when they are activated. A balance between activation and inhibition signals is important for a targeted and effective T cell response. Thermal injury is characterized by an immune dysfunction and hyperactive T cells visible at day 10 postburn. In this study, our objective was to evaluate T cell sensitivity to GC following thermal injury and to identify mechanisms that could modulate their sensitivity. One mechanism that we hypothesized was increased p38 mitogen-activated protein kinase (MAPK) activity that could lead to GC resistance. Male C57BL/6 mice underwent a full-thickness 20% total body surface area. At 10 days postinjury, splenic T cells were isolated. Glucocorticoid receptor (GR) expression was higher in T cells from burn-injured mice. Interestingly, these cells were also less sensitive to GC-induced apoptosis prior to and poststimulation. Furthermore, anti-CD3-activated T cells from burn-injured mice showed increased proliferation and CD25 expression, which resisted corticosterone's (CORT) suppressive effect. Anti-CD3-activated [CD4.sup.+][CD44.sup.+] memory cells from burn-injured mice expressed the highest level of CD25 and were resistant to CORT. Increased phosphorylation of p38 MAPK was also noted in activated T cells from burn-injured mice. Pharmacological inhibition of p38 MAPK decreased cell proliferation and normalized interferon-[gamma] (IFN[gamma]) production. In conclusion, we demonstrate that a unique event like burn injury induces a loss of sensitivity to GC in splenic T cells and have identified p38 MAPK as a key modulator for this resistance. T lymphocyte; resistance; mitogen-activated protein kinase doi: 10.1152/ajpendo.00084.2010.

The neighbor of Brca1 gene (Nbr1) functions as an autophagy receptor involved in targeting ubiquitinated proteins for degradation. It also has a dual role as a scaffold protein to regulate growth-factor receptor and downstream signaling pathways. We show that genetic truncation of murine Nbr1 leads to an age-dependent increase in bone mass and bone mineral density through increased osteoblast differentiation and activity. At 6 mo of age, despite normal body size, homozygous mutant animals ([Nbr1.sup.tr/tr]) have ~50% more bone than littermate controls. Truncated Nbr1 (trNbr1) co-localizes with p62, a structurally similar interacting scaffold protein, and the autophagosome marker LC3 in osteoblasts, but unlike the full-length protein, trNbr1 fails to complex with activated p38 MAPK. [Nbr1.sup.tr/tr] osteoblasts and osteoclasts show increased activation of p38 MAPK, and significantly, pharmacological inhibition of the p38 MAPK pathway in vitro abrogates the increased osteoblast differentiation of [Nbr1.sup.tr/tr] cells. Nbr1 truncation also leads to increased p62 protein expression. We show a role for Nbr1 in bone remodeling, where loss of function leads to perturbation of p62 levels and hyperactivation of p38 MAPK that favors osteoblastogenesis. bone remodeling | osteoblasts | p62 | autophagy | light chain 3 doi/ 10.1073/pnas.0913058107

Babies are frequently exposed to cerebral hypoxia and ischemia (H/l) during the perinatal period as a result of stroke, problems with delivery, or postdelivery respiratory management. The sole approved treatment for acute stroke is tissue type plasminogen activator. H/I impairs pial artery dilation (PAD) induced by hypercapnia and hypotension, the impairment aggravated by type plasminogen activator and attenuated by the plasminogen activator inhibitor-1-derived peptide EEIIMD. Mitogen-activated protein kinase (MAPK), a family of at least three kinases, ERK, p38, and JNK, is upregulated after H/I and ERK contribute to impaired cerebrovasodilation. This study determined the roles of p38 and JNK MAPK in the impairment of dilation post-H/I in pigs equipped with a closed cranial window and the relationship between alterations in MAPK isoforms and EEIIMD-mediated cerebrovascular protection. Cerebrospinal fluid-phosphorylated (activated) p38 MAPK, but not JNK MAPK, was increased after I-I/I, an effect potentiated by intravenous EEIIMD administered 1 h postinjury. PAD in response to hypercapnia and hypotension was blunted by HA, but dilation was maintained by EEIIMD. PAD was further impaired by the p38 antagonist SB-203580 but unchanged by the JNK antagonist SP-600125. Isoproterenol-induced PAD was unchanged by H/I, EEIIMD, SB-203580, and SP-600125. These data indicate that postinjury treatment with EEIIMD attenuated impaired cerebrovasodilation post-H/l by upregulating p38 but not JNK. These data suggest that plasminogen activator inhibitor-l-based peptides and other approaches to upregulate p38 may offer a novel approach to increase the benefit-to-risk ratio of thrombolytic therapy for diverse central nervous system disorders associated with HA. cerebral circulation; newborn; plasminogen activator inhibitor-l; signal transduction; mitogen-activated protein kinase doi: 10.1152/ajpheart.00185.2010.

Nervous system function requires tight control over the number of synapses individual neurons receive, but the underlying cellular and molecular mechanisms that regulate synapse number remain obscure. Here we present evidence that a trans-synaptic interaction between EphB2 in the presynaptic compartment and ephrin-B3 in the postsynaptic compartment regulates synapse density and the formation of dendritic spines. Observations in cultured cortical neurons demonstrate that synapse density scales with ephrin-B3 expression level and is controlled by ephrin-B3-dependent competitive cell--cell interactions. RNA interference and biochemical experiments support the model that ephrin-B3 regulates synapse density by directly binding to Erk1/2 to inhibit postsynaptic Ras/mitogen-activated protein kinase signaling. Together these findings define a mechanism that contributes to synapse maturation and controls the number of excitatory synaptic inputs received by individual neurons. cell signaling | development | Ras/MAPK | synaptogenesis | competition doi/10.1073/pnas.0910644107

We have previously demonstrated that the activation of rat parathyroid calcium-sensing receptor (CaSR) upregulates VDR expression in vivo (Garfia B, Canadillas S, Luque F, Siendones E, Quesada M, Almaden Y, Aguilera-Tejero E, Rodriguez M. J Am Soc Nephrol 13: 2945-2952, 2002; Rodriguez ME, Almaden Y, Canadillas S, Canalejo A, Siendones E, Lopez I, Aguilera-Tejero E, Martin D, Rodriguez M. Am J Physiol Renal Phvsiol 292: F1390-F1395, 2007). The present study was designed to characterize the signaling system that mediates the stimulation of parathyroid VDR gene expression by extracellular calcium. Experiments were performed in vitro by the incubation of rat parathyroid glands and in vivo with normal and uremic (Nx) rats receiving injections of Ca[Cl.sub.2] or EDTA to obtain hypercalcemic or hypocalcemic clamps. A high calcium concentration increased VDR expression. The addition of arachidonic acid (AA) to the low-calcium medium produced an increase in VDR mRNA of the same magnitude as that observed with high calcium. The addition of ionophore m the low-calcium medium also increased VDR mRNA expression. High calcium or the addition of AA to the low-calcium medium induced the activation (phosphorylation) of ERK1/2-MAPK. The specific inhibition of the ERK1/2-MAPK activity prevented the stimulation of VDR expression by high calcium or AA. These results suggest that AA regulates parathyroid VDR gene expression through the activation of the ERKI/ 2-MAPK. CaSR activation induced the activation of transcription factor Sp1, but not of NF-[kappa]B p50 or p65 or activator protein-1. The addition of AA to the low-calcium medium increased specific DNA-binding activity of Sp1 to almost the same level as high calcium, which was prevented by the inhibition of ERK1/2. Furthermore, mithramycin A (a Sp1 inhibitor) prevented the upregulation of VDR mRNA by high calcium. Finally, both sham and Nx hypercalcemic rats showed similar increased levels of VDR mRNA compared with sham and Nx hypocalcemic rats. Our results demonstrate that extracellular calcium stimulates VDR expression in parathyroid glands through the elevation of the cytosolic calcium level and the stimulation of the [PLA.sub.2]-AA-dependent ERK1/2-pathway. Furthermore, the transcription factor Spl mediates this effect. parathyroid glands; transcription factor; arachidonic acid; CaSR; PTH doi: 10.1152/ajprenal.00529.2009.

Peroxisome proliferator-activated receptor (PPAR)-[gamma] is highly expressed in the collecting duct (CD), yet little is known about the effects of PPAR-[gamma] ligands, thiazolidinediones (TZDs), on CD cell structure and function. M1 mouse cortical CD cells were treated with 5 [micro]M troglitazone (TRO) and rosiglitazone (ROSI). First, growth was measured by [[sup.3]H]thymidine and [[sup.3]H]leucine incorporation, as well as analysis of cyclin D I and the CDK inhibitor p27 by Western blot. [[sup.3]H]thymidine incorporation was reduced by 56 and 24% by TRO and ROSI at 6 h, and [[sup.3]H]leucine by 21 and 10%. A similar growth inhibition was also observed after 24 h for thymidine, but leucine was reduced by 48 and 24%, respectively. Likewise, cyclin D1 was diminished 60% by TRO, and p27 was elevated 1.6-and 1.7-fold in response to TRO and ROSI. Next, epithelial cell integrity was assessed by measuring different markers by Western blot analysis. While fibronectin and [alpha]-smooth muscle actin levels were unchanged, by 24 h E-cadherin was decreased by 50%, and [beta]-catenin levels were reduced 2-and 1.5-fold in response to TRO and ROSI, respectively. GW9662, a PPAR-[gamma] antagonist, did not reverse any of the TZD responses in M 1 cells. Of interest, phosho-p38 levels were also elevated 2-fold in response to TRO and 2.3-fold to ROSI, but MAPK inhibition by PD98059 or SB203580 caused an additive inhibition of cell growth and did not alter E-cadherin or [beta]-catenin in response to TZDs. Finally, apoptotic death was assessed by Western blot, but cleaved caspase-3 levels were unchanged from 15 min to 24 h in response to TZDs, and TRO did not affect cell viability or reactive oxygen species generation. Our data suggest that TZDs cause a disruption of M1 cell integrity that is preceded by an inhibition of cell growth. This response is independent of p38 or PPAR-[gamma] activation. M1 collecting duct cells; troglitazone; rosiglitazone doi: 10.1152/ajprenal.00735.2009.

Cyclic AMP (cAMP) induces translocation of multidrug resistant protein 2 (Mrp2) to the canalicular membrane and activates p38 MAPK in rat hepatocytes. In this study, we tested the hypothesis that cAMP-induced Mrp2 translocation may be mediated via p38 MAPK. Studies were conducted in rat hepatocytes and in a human hepatoma cell line, HUH-7. In rat hepatocytes, cAMP increased Mrp2 translocation and p38 MAPK activity. These effects of cAMP were inhibited by SB203580, an inhibitor of p38 MAPK. Wortmannin, a specific inhibitor of phosphoinositide-3-kinase (PI3K), did not inhibit cAMP induced activation of p38 MAPK, indicating PI3K-independent activation of p38 MAPK by cAMP. To further define the role of p38 MAPK, molecular approaches were used to up- or downregulate p38 MAPK activity in HUH-7 cells using constitutively active (CA) and dominant-negative (DN) MAPK kinase 3 and 6 (MKK3/6). MKK3/6 are upstream kinases responsible for the activation of p38 MAPK. Cells transfected with CAMKK6 showed increased p38 MAPK activity and MRP2 translocation compared with empty vector, cAMP-induced activation of p38 MAPK was inhibited in cells transfected with DNMKK3/6 and DNMKK3, but not with DNMKK6. DNMKK3/6 and DNMKK3 also inhibited cAMP-induced MRP2 translocation, cAMP selectively activated p38[alpha] MAPK in HUH-7 cells. Knockdown of p38[alpha] MAPK by short heterodimer RNA resulted in decreased level of p38 MAPK and failure of cAMP to stimulate MRP2 translocation. Taken together, these results suggest that cAMP-induced MRP2 translocation in hepatic cells is mediated via PI3K-independent and MKK3-mediated activation of p38[alpha] MAPK. p38 MAPK isoforms; rat hepatocytes; Huh-7 cells; MAPK kinase; phosphoinositide-3-kinase doi: 10.1152/ajpgi.00506.2009.

Increased expression and activity of the intracellular glucocorticoid-reactivating enzyme 11[beta]-hydroxysteroid dehydrogenase type 1 (11[beta]-HSD1) contribute to dysfunction of adipose tissue. Although the pathophysiological role of 11[beta]-HSD1 in mature adipocytes has long been investigated, its potential role in preadipocytes still remains obscure. The present study demonstrates that the expression of 11[beta]-HSD1 in preadipocyte-rich stromal vascular fraction (SVF) cells in fat depots from ob/ob and diet-induced obese mice was markedly elevated compared with lean control. In 3T3-L1 preadipocytes, the level of mRNA and reductase activity of 11[beta]-HSD1 was augmented by TNF-[alpha], IL-1[beta], and LPS, with a concomitant increase in inducible nitric oxide synthase (iNOS), monocyte chemoattractant protein-1 (MCP-1), or IL-6 secretion. Pharmacological inhibition of 11[beta]-HSD1 and RNA interference against 11[beta]-HSD1 reduced the mRNA and protein levels of iNOS, MCP-1, and IL-6. In contrast, overexpression of 11[beta]-HSD1 further augmented TNF-[alpha]-induced iNOS, IL-6, and MCP-1 expression. Moreover, 11[beta]-HSD1 inhibitors attenuated TNF-[alpha]-induced phosphorylation of NF-[kappa]B p65 and p38-, JNK-, and ERK1/2-MAPK. Collectively, the present study provides novel evidence that inflammatory stimuli-induced 11[beta]-HSD1 in activated preadipocytes intensifies NF-[kappa]B and MAPK signaling pathways and results in further induction of proinflammatory molecules. Not limited to 3T3-L1 preadipocytes, we also demonstrated that the notion was reproducible in the primary SVF cells from obese mice. These findings highlight an unexpected, proinflammatory role of reamplified glucocorticoids within preadipocytes in obese adipose tissue. 11[beta]-hydroxysteroid dehydrogenase type 1; preadipocyte; nuclear factor-[kappa]B; mitogen-activated protein kinase; adipose inflammation doi: 10.1152/ajpendo.00320.2009.

In plant-pathogenic fungi, the pmk1 mitogen-activated protein kinase (MAPK) signalling pathway plays an essential role in regulating the development of penetration structures and the sensing of host-derived cues, but its role in other pathosystems such as fungal--fungal interactions is less clear. We report the use of a gene disruption strategy to investigate the pmk1-like MAPK, Lf pmk1 in the development of Lecanicillium fungicola (formerly Verticillium fungicola) infection on the cultivated mushroom Agaricus bisporus. Lf pmk1 was isolated using a degenerate PCR-based approach and was shown to be present in a single copy by Southern blot analysis. Quantitative RT-PCR showed the transcript to be fivefold upregulated in cap lesions compared with pure culture. Agrobacterium-mediated targeted disruption was used to delete a central portion of the Lf pmk1 gene. The resulting mutants showed normal symptom development as assessed by A. bisporus mushroom cap assays, sporulation patterns were normal and there were no apparent changes in overall growth rates. Our results indicate that, unlike the situation in fungal--plant pathogens, the pmk1-like MAPK pathway is not required for virulence in the fungal--fungal interaction between the L. fungicola pathogen and A. bisporus host. This observation may be of wider significance in other fungal--fungal and/or fungal--invertebrate interactions. DOI 10.1099/mic.0.034439-0