Research progress of sarcolipin-a new regulatory protein of sarcoplasmic reticulum Ca2+ ATPase / 中南大学学报(医学版)

Sarcolipin (SLN) is a 3 kD membrane protein found in sarcoplasmic reticulum (SR). It has 31 amino acid residues; SLN and phopholamban (PLB) are belong to the same protein family, so they have similar physiological functions. SLN inhibits sarcoplasmic reticulum Ca(2+) ATPase (SERCA) activity and reduces its affinity of Ca(2+), resulting in dysfunction of myocardial contraction and heart failure. However, much remains to be elucidated. SLN independently or in conjunction with PLB affects SERCA activity, imbalancing intracellular calcium homeostasis, and reducing myocardial contractivity; these effects promote the development of heart failure.

Proteoliposomes as matrix vesicles' biomimetics to study the initiation of skeletal mineralization

During the process of endochondral bone formation, chondrocytes and osteoblasts mineralize their extracellular matrix by promoting the formation of hydroxyapatite (HA) seed crystals in the sheltered interior of membrane-limited matrix vesicles (MVs). Ion transporters control the availability of phosphate and calcium needed for HA deposition. The lipidic microenvironment in which MV-associated enzymes and transporters function plays a crucial physiological role and must be taken into account when attempting to elucidate their interplay during the initiation of biomineralization. In this short mini-review, we discuss the potential use of proteoliposome systems as chondrocyte- and osteoblast-derived MVs biomimetics, as a means of reconstituting a phospholipid microenvironment in a manner that recapitulates the native functional MV microenvironment. Such a system can be used to elucidate the interplay of MV enzymes during catalysis of biomineralization substrates and in modulating in vitro calcification. As such, the enzymatic defects associated with disease-causing mutations in MV enzymes could be studied in an artificial vesicular environment that better mimics their in vivo biological milieu. These artificial systems could also be used for the screening of small molecule compounds able to modulate the activity of MV enzymes for potential therapeutic uses. Such a nanovesicular system could also prove useful for the repair/treatment of craniofacial and other skeletal defects and to facilitate the mineralization of titanium-based tooth implants.

Expression pattern of MAL in normal epithelial cells, benign tumor, and squamous cell carcinoma of larynx / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To compare the expression pattern of the MAL protein in normal and laryngeal carcinoma to derive possible implications of MAL in carcinoma development of larynx.@*METHOD@#Use the immunohistochemical technique to analyze the distribution of MAL in normal laryngeal epithelial cells, polyp of vocal cords, laryngeal atypical hyperplasia and laryngeal squamous cell carcinoma.@*RESULT@#MAL-like immunohistochemical reactions are strongly expressed in normal laryngeal epithelial cells and its expression is no significantly different in epithelial cells of the polyp of vocal cords. Comparatively, MAL expression is significantly down regulated in laryngeal atypical hyperplasia and laryngeal squamous cell carcinomas (P < 0.05).@*CONCLUSION@#MAL is normally expressed in laryngeal epithelial cells and its expression changes at early stages of carcinoma development. MAL, therefore, is a potential marker for early diagnosis of laryngeal squamous cell carcinoma.

Protein-mediated surface structuring in biomembranes

The lipids and proteins of biomembranes exhibit highly dissimilar conformations, geometrical shapes, amphipathicity, and thermodynamic properties which constrain their two-dimensional molecular packing, electrostatics, and interaction preferences. This causes inevitable development of large local tensions that frequently relax into phase or compositional immiscibility along lateral and transverse planes of the membrane. On the other hand, these effects constitute the very codes that mediate molecular and structural changes determining and controlling the possibilities for enzymatic activity, apposition and recombination in biomembranes. The presence of proteins constitutes a major perturbing factor for the membrane sculpturing both in terms of its surface topography and dynamics. We will focus on some results from our group within this context and summarize some recent evidence for the active involvement of extrinsic (myelin basic protein), integral (Folch-Lees proteolipid protein) and amphitropic (c-Fos and c-Jun) proteins, as well as a membrane-active amphitropic phosphohydrolytic enzyme (neutral sphingomyelinase), in the process of lateral segregation and dynamics of phase domains, sculpturing of the surface topography, and the bi-directional modulation of the membrane biochemical reactivity.

Making an experimental animal model for multiple sclerosis

To understand the mechanism of Multiple Sclerosis [MS], an autoimmune demyelinating disease, the researchers developed an experimental animal model for MS, which is called EAE [Experimental Allergic Encephalomyelitis]. There are several methods for inducing this animal model. In this research the active EAE, which is developed by injecting bovine myelin antigens into genetically susceptible animals, was used. Proteolipid protein [PLP], which is a prominent neuroantigen, was extracted from fresh bovine brain, and used for inducing EAE in female Balb/C and Guinea pig. Animals were weighed and examined daily for clinical symptoms. Also histological sections from EAE brains were prepared. These sections showed infiltration, congestion and demyelination

Membrane proteins: functional and structural studies using reconstituted proteoliposomes and 2-D crystals

Reconstitution of membrane proteins into lipid bilayers is a powerful tool to analyze functional as well as structural areas of membrane protein research. First, the proper incorporation of a purified membrane protein into closed lipid vesicles, to produce proteoliposomes, allows the investigation of transport and/or catalytic properties of any membrane protein without interference by other membrane components. Second, the incorporation of a large amount of membrane proteins into lipid bilayers to grow crystals confined to two dimensions has recently opened a new way to solve their structure at high resolution using electron crystallography. However, reconstitution of membrane proteins into functional proteoliposomes or 2-D crystallization has been an empirical domain, which has been viewed for a long time more like "black magic" than science. Nevertheless, in the last ten years, important progress has been made in acquiring knowledge of lipid-protein-detergent interactions and has permitted to build upon a set of basic principles that has limited the empirical approach of reconstitution experiments. Reconstitution strategies have been improved and new strategies have been developed, facilitating the success rate of proteoliposome formation and 2-D crystallization. This review deals with the various strategies available to obtain proteoliposomes and 2-D crystals from detergent-solubilized proteins. It gives an overview of the methods that have been applied, which may be of help for reconstituting more proteins into lipid bilayers in a form suitable for functional studies at the molecular level and for high-resolution structural analysis

Inflammatory reaction and alterations of pulmonary surfactant in Pseudomonas Aeruginosa pneumonia in immunocompromised rats / 中华医学杂志(英文版)

Pulmonary surfactant ( PS ) compromises lipids and surfactant proteins (SP) and lines on the alveolar air-liquid interface. It can reduce surface tension, prevent alveoli from collapse and reduce alveoli edema by disaturated dipalmitoylphosphatidylcholine. It also modulates the pulmonary immunology by SP-A and SP-D. In this study,we established a rat model of immunocompromised host (ICH) with pulmonary infection of Pseudomonas aeruginosa (P. aeruginosa), then studied its pulmonary inflammatory reaction and analyzed the concentration of lipids and SP-A in bronchoalveolar lavage fluid (BALF) during infection.

Purification and characterization of receptors for myoinositol trisphosphate and myoinositol tetrakis phosphate from Entamoeba histolytica.

The microsomal fraction from the log phase of Entamoeba histolytica cells contains Ins(1,4,5)P3 and Ins(1,3,4,5)P4 binding activity. The binding proteins/receptors for both Ins(1,4,5)P3 and Ins(1,3,4,5)P4 were purified and found to be specific for each ligand. The molecular masses for native proteins for InsP3 and InsP4 are 138 kDa and 130 kDa respectively having subunits of 69 kDa and 64 kDa respectively. That these proteins are associated with Ca2+ release was confirmed by including these proteins separately in proteoliposomes and adding InsP3 and InsP4 in both the cases.

Surfactant protein-A: new insights into an old protein--II.

Pulmonary surfactant is a lipoprotein substance that lines the lungs and helps reduce surface tension. Surfactant associated protein-A (SP-A) is the most abundant non-serum protein in pulmonary surfactant. This complex glycoprotein aids in the synthesis, secretion and recycling of surfactant phospholipids, and facilitates the reduction of surface tension by surfactant phospholipids. Recent evidence has highlighted the role of SP-A in the innate immune system present in the lung. SP-A may play a major role in defense against pathogens by interacting with both infectious agents and the immune system. Factors that affect fetal lung maturation, e.g. gestational age and hormones regulate SP-A gene expression. Mediators of immune function also regulate SP-A levels. A number of lung disorders, including infectious diseases and respiratory distress syndrome are associated with abnormal alveolar SP-A levels. SP-A can no longer be called a lung-specific protein, since it has recently been detected in other tissues. In most species, SP-A is encoded by a single gene, however in humans it is encoded by two, very similar genes. Models for the structure of the human SP-A protein molecule have been proposed, suggesting that the mature alveolar SP-A molecule is composed of both gene products. The study of SP-A may provide information helpful in understanding disease processes and formulating new treatment modalities.

Surfactant protein-A: new insights into an old protein--Part I.

Pulmonary surfactant is a lipoprotein substance that lines the lungs and helps reduce surface tension. Surfactant associated protein-A (SP-A) is the most abundant non-serum protein in pulmonary surfactant. This complex glycoprotein aids in the synthesis, secretion and recycling of surfactant phospholipids, and facilitates the reduction of surface tension by surfactant phospholipids. Recent evidence has highlighted the role of SP-A in the innate immune system present in the lung. SP-A may play a major role in defense against pathogens by interacting with both infectious agents and the immune system. Factors that affect fetal lung maturation, e.g., gestational age and hormones, regulate SP-A gene expression. Mediators of immune function also regulate SP-A levels. A number of lung disorders, including infectious diseases and respiratory distress syndrome are associated with abnormal alveolar SP-A levels. SP-A can no longer be called a lung-specific protein, since it has recently been detected in other tissues. In most species, SP-A is encoded by a single gene, however in humans it is encoded by two, very similar genes. Models for the structure of the human SP-A protein molecule have been proposed, suggesting that the mature alveolar SP-A molecule is composed of both gene products. The study of SP-A may provide information helpful in understanding disease processes and formulating new treatment modalities.

Interaction of pulmonary surfactant-associated protein (SP-A) with surfactant lipids.

A pulmonary surfactant-associated protein complex with components of 36, 32 and 28 kDa was isolated from human lung homogenates and reassembled with surfactant lipids prepared as small unilamellar liposomes. The role of divalent cations in the assembly of this recombinant lipoprotein complex was studied by monitoring the changes in turbidity, intrinsic tryptophanyl fluorescence and surface activity. The protein-facilitated lipid aggregation was promoted on addition of 5 to 20 mM Ca2+. Intrinsic fluorescence measurements on SP-A (28-36 kDa) indicated that the tryptophan side chains were in a relatively hydrophobic environment, that the wavelength of maximum fluorescence emission and also the relative fluorescence, were changed upon the binding of lipid. Tryptophanyl fluorescence of the lipoprotein assembly was quenched as indicated by a reduction in the effective Stern-Volmer constant. These results suggest that Ca2+ lipid-protein interactions are involved in the structure and function of extracellular lung surfactant assembly.

Fijacion de 5-hidroxitriptamina a proteinas hidrofobicas cerebrales. Caracterizacion y localizacion subcelular de las proteinas cerebrales. / Binding of 5hydroxytryptamine to cerebral hydrophobic proteins. Characterization and subcelluar distribution of cerebral proteins

Se ha estudiado la naturaleza de la substancia responsable de la fijacion de 5-HT encontrada en extractos lipidicos de corteza cerebral, caracterizandola como un proteolipido (proteina hidrofobica de membrana). Se ha comprobado la existencia de dos de dichos protolipidos con capacidad para fixar 5-HT.Se determino, en ambos, la presencia de fosfolipidos y triptofano, asi como la ausencia de glucidos reductores y la de grupos amino libres. La prueba definitiva de su naturaleza proteica se consiguio mediante la determinacion de la composicion de aminoacidos del compuesto responsable de la fijacion. Se estudio tambien su localizacion subcelular, en contrandose que la fijacion fue maxima en extractos procedentes de membranas de terminales nerviosos