Multiexon deletion in the procollagen III gene is associated with mild Ehlers-Danlos syndrome type IV

We have characterized a deletion of approximately 9 kilobases which spans from intron 33 to exon 48 of one pro-alpha 1 (III) collagen allele in a patient with Ehlers-Danlos syndrome type IV. The mutation results in the production of an in-frame species of mRNA which lacks the sequences corresponding to residues 595-1,008 of the triple-helical domain. Thus, half of the pro-alpha 1 (III) chains synthesized by the patient's fibroblasts are nearly 30% shorter than normal. The procollagen III molecules composed of either three normal length or three shortened chains are thermally stable and efficiently secreted. In contrast, the procollagen III molecules that contain one or two shortened chains are unstable and are not secreted. Failure to secrete unstable molecules and a residual functional role of the shortened but stable homotrimers may explain the somewhat milder phenotype of this individual compared with that of another Ehlers-Danlos type IV patient bearing a deletion of similar size in the amino-terminal portion of the alpha 1 (III) collagen chain.     

Actin organization and fibrin-clot retractile activity of cultured mouse fibroblasts

Summary It is known that human and animal fibroblasts are able to induce the retraction of a fibrin clot. In the present study the correlation between (i) fibrinclot retractile (FCR) activity, (ii) the number of actin stress-lines in mouse fibroblasts during growth in culture, and (iii) the sensitivity of actin stress-lines to a powerful actin-depolymerizing factor (ADF), present in plasma and serum of humans and laboratory animals was investigated. Fibroblasts at early passages (2–4) were tested for these parameters at various intervals after seeding (24, 96, and 168 h). The number of actin stress-lines was progressively higher, while the sensitivity to ADF action was progressively lower in cells cultured from 24 to 168 h; the FCR capacity was significantly decreased at 168 h. These data suggest that cells containing weakly polymerized and/or stabilized actin are more active than those containing highly polymerized and/or stabilized actin in triggering fibroblast contraction.     

Glutamate as a Putative Transmitter in the Cerebellum: Stimulation by GABA of Glutamic Acid Release from Specific Pools

The aim of the present paper was to determine whether the release of glutamate from putative "glutamergic" terminals in the cerebellum is influenced by gamma-aminobutyric acid (GABA). In a group of preliminary experiments, we present biochemical evidence in favour of a neurotransmitter role of glutamate in the cerebellum: (1) endogenous glutamate was released from depolarized cerebellar synaptosomal preparations in a Ca2+-dependent away; (2) [14C]glutamate was synthesized from [14C]glutamine in cerebellar synaptosomes, and the newly synthesized [14C]glutamate was released released in a Ca2+-dependent way; (3) the elevation of cyclic GMP elicited by depolarization of cerebellar slices in the presence of Ca2+ was partly reversed by the glutamate antagonist glutamic acid diethyl ester, which probably prevented the interaction of endogenously released glutamate with postsynaptic receptors. GABA and muscimol at low concentrations (2--20 micrometers) potentiated the depolarization-induced release of D-[3H]aspartate (a glutamate analogue which labels the glutamate "reuptake pool") from cerebellar synaptosomes. The effect was concentration dependent and was largely prevented by two GABA antagonists, bicuculline and picrotoxin. The stimulation of D-[3H]aspartate release evoked by muscimol was linearly related to the logarithm of K+ concentration in the depolarizing medium. GABA did not affect the overall release of endogenous glutamate, but potentiated, in a picrotoxin-sensitive manner, the depolarization-evoked release of [14C]glutamate previously synthesized from [14C]glutamine. Since nerve endings are the major site of glutamate synthesis from glutamine, GABA and muscimol appear to exert their stimulatory effect at the level of "glutamergic" nerve terminals, probably after interacting with presynaptic GABA receptors. The possible functional significance of these findings is briefly discussed.     

The action of the adenosylhomocysteine hydrolase inhibitor, 3-deazaadenosine,on phagocytic function of mouse macrophages and human monocytes

An inhibitor of adenosylhomocysteine hydrolase, 3-deazaadenosine, caused profound inhibition of phagocytosis of opsonized erythrocytes by mouse resident peritoneal macrophages $\text{in}\text{vitro}$. The inhibition was evident at concentrations as low as 2×10^?7M, and increased with increasing concentration and time of exposure to the analogue. It was not associated with detachment of the macrophage monolayers or with loss of cell viability. Although the inhibition was not reversible, progression of the functional impairment was interrupted by washing out the analogue. In striking contrast, phagocytic function of human blood monocytes was unaffected by 3-deazaadenosine.     

Predicting potentially pathogenic effects of hRPE65 missense mutations: a computational strategy based on molecular dynamics simulations

The human retinal pigment epithelium-specific 65-kDa protein (hRPE65) plays a crucial role within the retinoid visual cycle and several mutations affecting either its expression level or its enzymatic function are associated with inherited retinal diseases such as Retinitis Pigmentosa. The gene therapy product voretigene neparvovec (Luxturna) has been recently approved for treating hereditary retinal dystrophies; however, the treatment is currently accessible only to patients presenting confirmed biallelic mutations that severely impair hRPE65 function, and many reported hRPE65 missense mutations lack sufficient evidences for proving their pathogenicity. In this context, we developed a computational approach aimed at evaluating the potential pathogenic effect of hRPE65 missense variants located on the dimerisation domain of the protein. The protocol evaluates how mutations may affect folding and conformation stability of this protein region, potentially helping clinicians to evaluate the eligibility for gene therapy of patients diagnosed with this type of hRPE65 variant of uncertain significance.