From Mice to Humans: An Overview of the Potentials and Limitations of Current Transgenic Mouse Models of Major Muscular Dystrophies and Congenital Myopathies.

Muscular dystrophies are a group of more than 160 different human neuromuscular disorders characterized by a progressive deterioration of muscle mass and strength. The causes, symptoms, age of onset, severity, and progression vary depending on the exact time point of diagnosis and the entity. Congenital myopathies are rare muscle diseases mostly present at birth that result from genetic defects. There are no known cures for congenital myopathies; however, recent advances in gene therapy are promising tools in providing treatment. This review gives an overview of the mouse models used to investigate the most common muscular dystrophies and congenital myopathies with emphasis on their potentials and limitations in respect to human applications.

Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) Pathway Is Induced by Mechanical Load and Reduces the Activity of Hedgehog Signaling in Chondrogenic Micromass Cell Cultures.

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neurohormone exerting protective function during various stress conditions either in mature or developing tissues. Previously we proved the presence of PACAP signaling elements in chicken limb bud-derived chondrogenic cells in micromass cell cultures. Since no data can be found if PACAP signaling is playing any role during mechanical stress in any tissues, we aimed to investigate its contribution in mechanotransduction during chondrogenesis. Expressions of the mRNAs of PACAP and its major receptor, PAC1 increased, while that of other receptors, VPAC1, VPAC2 decreased upon mechanical stimulus. Mechanical load enhanced the expression of collagen type X, a marker of hypertrophic differentiation of chondrocytes and PACAP addition attenuated this elevation. Moreover, exogenous PACAP also prevented the mechanical load evoked activation of hedgehog signaling: protein levels of Sonic and Indian Hedgehogs and Gli1 transcription factor were lowered while expressions of Gli2 and Gli3 were elevated by PACAP application during mechanical load. Our results suggest that mechanical load activates PACAP signaling and exogenous PACAP acts against the hypertrophy inducing effect of mechanical load.

Pituitary Adenylate Cyclase-Activating Polypeptide Is Upregulated in Murine Skin Inflammation and Mediates Transient Receptor Potential Vanilloid-1-Induced Neurogenic Edema.

Although pituitary adenylate cyclase-activating polypeptide (PACAP) was described as a key vasoregulator in human skin, little is known about its expression in mouse skin. As it is important to investigate PACAP signaling in translational mouse dermatitis models, we determined its presence, regulation, and role in neurogenic and non-neurogenic cutaneous inflammatory mechanisms. The mRNA of PACAP and its specific receptor PAC1 was detected with real-time PCR in several skin regions at comparable levels. PACAP-38-immunoreactivity measured with radioimmunoassay was similar in plantar and dorsal paw skin and the ear but significantly smaller in the back skin. PACAP and PAC1 mRNA, as well as PACAP-38 and PAC1 protein expression, significantly increased in the plantar skin after intraplantar administration of capsaicin (50 µl, 100 µg ml(-1)), an agonist of the transient receptor potential vanilloid 1 (TRPV1) receptor, evoking chiefly neurogenic inflammation without inflammatory cell accumulation. Intraplantar complete Freund's adjuvant (CFA; 50 µl, 1 mg ml(-1)) also increased PACAP/PAC1 mRNA but not the PACAP peptide. Capsaicin-induced neurogenic paw edema, but not CFA-evoked non-neurogenic swelling, was significantly smaller in PACAP-deficient mice throughout a 24-hour period. To our knowledge, we provide previously unreported evidence for PACAP and PAC1 expression upregulation during skin inflammation of different mechanisms and for its pro-inflammatory function in neurogenic edema formation.

Endocannabinoids modulate human epidermal keratinocyte proliferation and survival via the sequential engagement of cannabinoid receptor-1 and transient receptor potential vanilloid-1.

We have recently shown that lipid mediators of the emerging endocannabinoid system (ECS) are key players of growth control of the human pilosebaceous unit. In this study, we asked whether the prototypic endocannabinoid anandamide (N-arachidonoylethanolamine, AEA) has a role in growth and survival of epidermal keratinocytes (KCs). Using human cultured KCs and skin organ-culture models, and by employing combined pharmacological and molecular approaches, we provide early evidence that AEA markedly suppresses KC proliferation and induces cell death, both in vitro and in situ. Moreover, we present that these cellular actions are mediated by a most probably constitutively active signaling mechanism that involves the activation of the metabotropic cannabinoid receptor CB(1) and a sequential engagement of the "ionotropic cannabinoid receptor" transient receptor potential vanilloid-1 (TRPV1). Finally, we demonstrate that the cellular effects of AEA are most probably due to a Ca(2+) influx via the non-selective, highly Ca(2+)-permeable ion channel TRPV1, and the concomitant elevation of intracellular Ca(2+) concentration. The data reported here may encourage one to explore whether the targeted manipulation of the above signaling pathway of the cutaneous ECS could become a useful adjunct treatment strategy for hyperproliferative human dermatoses such as psoriasis or KC-derived skin tumors.

Effect of natural phenol derivatives on skeletal type sarcoplasmic reticulum Ca2+ -ATPase and ryanodine receptor.

The effect of natural phenol derivatives was studied on skeletal type sarcoplasmic reticulum Ca(2+)-ATPase and ryanodine receptor. The majority of the tested derivatives exerted inhibitory effect on the Ca(2+)-ATPase with an ascending sequence in regard to their effectiveness (IC(50)): cineole (3.33 mM) < ortho-vanillin (IC(50 )=1.13 mM) < 4-methyl-2-nitrophenol (1104 microM) < vanillin (525 microM) < thymol (224 microM) < carvacrol (162 microM). In two cases biphasic characteristic was observed: trans-anethole and meta-anisaldehyde first caused activation followed by inhibition (with IC(50)-s of 141 and 1903 microM respectively) as their concentration was increased. In some cases (cineole, ortho-vanillin, meta-anisaldehyde) total inhibition of Ca(2+)-ATPase could not be reached as the result of the limited solubility of these drugs. Para-anisaldehyde and 6-amino-meta-cresol did not show any effect up to 3 mM. In Ca(2+) release experiments drugs were applied on heavy sarcoplasmic reticulum vesicles isolated from skeletal muscle and actively loaded with calcium. Only thymol and carvacrol were able to evoke Ca(2+) release with EC(50) values of 158 +/- 16 and 211 +/- 55 microM respectively. Furthermore the effect of thymol and carvacrol was tested on the isolated ryanodine receptor incorporated into artificial lipid bilayer. Both drugs activated the RyR when applied in concentrations identical to their EC(50) values. These observations show that small differences in the structure of phenol derivatives sometimes have little impact on their effect on the sarcoplasmic reticulum Ca(2+)-ATPase or ryanodine receptor (thymol and carvacrol) whereas in certain cases they can completely abolish a particular effect (para- and meta-anisaldehyde).