Immunological characterization of the mitochondrial 2-oxoglutarate carrier from liver and heart. Organ specificity

Antibodies have been prepared against the 2-oxoglutarate transport proteins purified from bovine heart and rat liver mitochondria. The anti-heart antiserum cross-reacts with the 2-oxoglutarate carrier (OGC) from beef, pig, rat and rabbit heart, but not with the OGC from liver of the same animals. Conversely, the anti-liver antiserum recognizes the carrier protein from liver of all species tested but not from heart. Immunoinactivation of oxoglutarate transport activity by the antibodies is also tissue specific. Peptide maps of purified OGC show structural differences between the carrier from heart and liver of the same animal species. These results indicate the existence of isoforms of the OGC in heart and liver.     

Fibromodulin reduces scar size and increases scar tensile strength in normal and excessive‐mechanical‐loading porcine cutaneous wounds

Hypertrophic scarring is a major postoperative complication which leads to severe disfigurement and dysfunction in patients and usually requires multiple surgical revisions due to its high recurrence rates. Excessive‐mechanical‐loading across wounds is an important initiator of hypertrophic scarring formation. In this study, we demonstrate that intradermal administration of a single extracellular matrix (ECM) molecule—fibromodulin (FMOD) protein—can significantly reduce scar size, increase tensile strength, and improve dermal collagen architecture organization in the normal and even excessive‐mechanical‐loading red Duroc pig wound models. Since pig skin is recognized by the Food and Drug Administration as the closest animal equivalent to human skin, and because red Duroc pigs show scarring that closely resembles human proliferative scarring and hypertrophic scarring, FMOD‐based technologies hold high translational potential and applicability to human patients suffering from scarring—especially hypertrophic scarring.     

Biogenesis of eel liver citrate carrier (CIC): negative charges can substitute for positive charges in the presequence

A family of structurally related carrier proteins mediates the flux of metabolites across the mitochondrial inner membrane. Differently from most other mitochondrial proteins, members of the carrier family are synthesized without an amino-terminal targeting sequence. However, in some mammalian and plant species, representatives were identified that carry a positively charged presequence. To obtain data on a carrier protein from lower vertebrates, we determined the primary structure of eel mitochondrial citrate carrier (CIC) and investigated its import pathway into the target organelle. The protein carries a cleavable presequence of 20 amino acids, including two positively charged residues. The cleavage site is recognized by a magnesium-dependent peptidase in the intermembrane space. The presequence is dispensable both for targeting and translocation, but prior to import into mitochondria, significantly increases the solubility of the precursor protein. This effect is completely retained if the positive charges are exchanged with negative charges. Following this observation, we found that several carrier proteins appear to carry non-cleavable presequences that may similarly act as charged intramolecular chaperones.     

False occurrences of functional motifs in protein sequences highlight evolutionary constraints

Background

False occurrences of functional motifs in protein sequences can be considered as random events due solely to the sequence composition of a proteome. Here we use a numerical approach to investigate the random appearance of functional motifs with the aim of addressing biological questions such as: How are organisms protected from undesirable occurrences of motifs otherwise selected for their functionality? Has the random appearance of functional motifs in protein sequences been affected during evolution?

Results

Here we analyse the occurrence of functional motifs in random sequences and compare it to that observed in biological proteomes; the behaviour of random motifs is also studied. Most motifs exhibit a number of false positives significantly similar to the number of times they appear in randomized proteomes (=expected number of false positives). Interestingly, about 3% of the analysed motifs show a different kind of behaviour and appear in biological proteomes less than they do in random sequences. In some of these cases, a mechanism of evolutionary negative selection is apparent; this helps to prevent unwanted functionalities which could interfere with cellular mechanisms.

Conclusion

Our thorough statistical and biological analysis showed that there are several mechanisms and evolutionary constraints both of which affect the appearance of functional motifs in protein sequences.

     

Study of the mechanism of Ras-dva small GTPase intracellular localization

An analysis of amino acid sequences of small GTPases of the Ras-dva family allowed us to determine the C-terminal prenylation motif, which could be responsible for the membrane localization of these proteins. We demonstrated using in vivo EGFP tracing that the Ras-dva small GTPases from Xenopus laevis embryo cells and NIH-3T3 fibroblasts are localized on both plasma membranes and endomembranes (the endoplasmic reticulum, the Golgi apparatus, and vesicles). At the same time, the replacement of the Cys residue, the SH group of which must be theoretically farnesylated, in the C-terminal prenylation motif of the Ras-dva small GTPase by the Ser residue prevented the membrane localization of the protein. These results indicate that the C-terminal prenylation site is critical for the membrane localization of small Ras-dva GTPases.     

How Does a Voltage Sensor Interact with a Lipid Bilayer? Simulations of a Potassium Channel Domain

The nature of voltage sensing by voltage-activated ion channels is a key problem in membrane protein structural biology. The way in which the voltage-sensor (VS) domain interacts with its membrane environment remains unclear. In particular, the known structures of Kv channels do not readily explain how a positively charged S4 helix is able to stably span a lipid bilayer. Extended (2 x 50 ns) molecular dynamics simulations of the high-resolution structure of the isolated VS domain from the archaebacterial potassium channel KvAP, embedded in zwitterionic and in anionic lipid bilayers, have been used to explore VS/lipid interactions at atomic resolution. The simulations reveal penetration of water into the center of the VS and bilayer. Furthermore, there is significant local deformation of the lipid bilayer by interactions between lipid phosphate groups and arginine side chains of S4. As a consequence of this, the electrostatic field is "focused" across the center of the bilayer.     

Neuroendocrine small cell carcinoma of the cervix associated with endocervical adenocarcinoma: a case report

BACKGROUND: Small-cell carcinoma (SCC) of the cervix is an uncommon member of the neuroendocrine group of cervical carcinomas that is frequently intermixed with a non-SCC component in the form of an adenocarcinoma (ADC) or squamous carcinoma. CASE: Colposcopy revealed a cervical mass in a 41-year-old woman and a Pap smear the presence of some tumor cells from SCC, which was confirmed by subsequent biopsy. The patient received 3 cycles of chemotherapy and then underwent major surgery. The cervical samples showed areas of endocervical ADC adjacent to and intermixed with the SCC. Reviewing the Pap smear, a previously missed malignancy was recognized. On subsequent molecular investigation to assess clonality by microsatellite analysis, the presence of HR-HPV DNA18 on real-time polymerase chain reaction, p16(INK4a) fluorescence in situ hybridization status and the corresponding immunohistochemical expression supported the hypothesis that the two components of the tumor shared the same cell origin. CONCLUSION: SCC of the cervix is a rare but distinct HR-HPV-18-related cervical carcinoma often intermixed with a clonally related non-small cell component consisting of an ADC or squamous carcinoma. The presence of SCC tumor cells in a cervical smear should prompt a search for malignant glandular or squamous tumor cells.     

Vanadium(V) complexes with hydrazides and their spectroscopic and biological properties

The present study explores the synthesis and inhibitory potential of vanadium(V) complexes of hydrazides (1c–12c) against oxidative enzymes including xanthine oxidase and lipoxygenase (LOX). In addition, non-enzymatic radical scavenging activities of these complexes were also determined. On the basis of spectral, elemental and physical data, synthesized vanadium(V) complexes are tentatively assigned to have an octahedral geometry with two hydrazide ligands and two oxo groups forming a negatively charged sphere complex with ammonium as counter ion. This is further verified by the conductivity studies of the complexes. Results show that hydrazide ligands (1–12) and their respective vanadium(V) complexes (1c–12c) posses scavenging and inhibition potential against DPPH and LOX, respectively. However, contrary to that uncoordinated ligands showed no activity against nitric oxide, superoxide and xanthine oxidase whereas their complexes showed varying degree of activity. These studies indicate that geometry of complex, nature and position of substituent groups play a vital role in scavenging and inhibition potential of these compounds.     

Genomic integrity of human induced pluripotent stem cells:Reprogramming,differentiation and applications

Ten years after the initial generation of induced pluripotent stem cells(hiPSCs)from human tissues, their potential is no longer questioned, with over 15000 publications listed on PubMed, covering various fields of research; including disease modeling, cell therapy strategies, pharmacology/toxicology screening and 3 D organoid systems. However, despite evidences that the presence of mutations in hiPSCs should be a concern, publications addressing genomic integrity of these cells represent less than 1% of the literature. After a first overview of the mutation types currently reported in hiPSCs, including karyotype abnormalities, copy number variations, single point mutation as well as uniparental disomy, this review will discuss the impact of reprogramming parameters such as starting cell type and reprogramming method on the maintenance of the cellular genomic integrity. Then, a specific focus will be placed on culture conditions and subsequent differentiation protocols and how their may also trigger genomic aberrations within the cell population of interest.Finally, in a last section, the impact of genomic alterations on the possible usages of hiPSCs and their derivatives will also be exemplified and discussed. We will also discuss which techniques or combination of techniques should be used to screen for genomic abnormalities with a particular focus on the necessary quality controls and the potential alternatives.