Functional characterization of two RAB27A missense mutations found in Griscelli syndrome type 2

Human Griscelli syndrome type 2 (GS-2) is characterized by partial albinism and a severe immunologic disorder as a result of RAB27A mutations. In melanocytes, Rab27A forms a tripartite complex with a specific effector Slac2-a/melanophilin and myosin Va, and the complex regulates melanosome transport. Here, we report a novel homozygous missense mutation of Rab27A, i.e. K22R, in a Persian GS-2 patient and the results of analysis of the impact of the K22R mutation and the previously reported I44T mutation on protein function. Both mutations completely abolish Slac2-a/melanophilin binding activity but they affect the biochemical properties of Rab27A differently. The Rab27A(K22R) mutant lacks the GTP binding ability and exhibits cytosolic localization in melanocytes. By contrast, neither intrinsic GTPase activity nor melanosomal localization of Rab27A is affected by the I44T mutation, but the Rab27A(I44T) mutant is unable to recruit Slac2-a/melanophilin. Interestingly, the two mutations differently affect binding to other Rab27A effectors, Slp2-a, Slp4-a/granuphilin-a, and Munc13-4. The Rab27A(K22R) mutant normally binds Munc13-4, but not Slp2-a or Slp4-a, whereas the Rab27A(I44T) mutant shows reduced binding activity to Slp2-a and Munc13-4 but normally binds Slp4-a.     

PPAR-γ: Its ligand and its regulation by microRNAs

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily. PPARs are categorized into three subtypes, PPARα, β/δ, and γ, encoded by different genes, expressed in diverse tissues and participate in various biological functions and can be activated by their metabolic derivatives in the body or dietary fatty acids. The PPAR-γ also takes parts in the regulation of energy balance, lipoprotein metabolism, insulin sensitivity, oxidative stress, and inflammatory signaling. It has been implicated in the pathology of numerous diseases including obesity, diabetes, atherosclerosis, and cancers. Among various cellular and molecular targets that are able to regulate PPAR-γ and its underlying pathways, microRNAs (miRNAs) appeared as important regulators. Given that the deregulation of these molecules via targeting PPAR-γ could affect initiation and progression of various diseases, identification of miRNAs that affects PPAR-γ could contribute to the better understanding of roles of PPAR-γ in various biological and pathological conditions. Here, we have summarized the function and various ligands of PPAR-γ and have highlighted various miRNAs involved in the regulation of PPAR-γ.     

Chemo-somatosensory evoked potentials: A sensitive tool to assess conditioned pain modulation?

Background: Chemo-somatosensory evoked potentials (CSSEPs) elicited by chemical stimulation (CO₂ gas) of the nasal mucosa have been shown to be sensitive enough to pick up even weak analgesic effects. With the present study we wanted to investigate whether CSSEPs are also a sensitive tool to capture endogenous pain inhibitory mechanisms elicited by conditioned pain modulation (CPM; where a first conditioning stimulus reduces the sensitivity for a second test stimulus) with a conditioning stimulus of rather low noxious load.

Methods: Seventeen healthy participants were tested for CPM effects (conditioning stimulus: tonic heat pain with intensities around the pain threshold induced via a thermode; test stimulus: chemonasal stimulation (73% and 78% CO₂)) on CSSEPs and on self-report ratings.

Results: We found significant CPM effects in the CSSEPS, with reduced amplitudes and prolonged latencies at several electroencephalogram (EEG) recording positions when using the lower CO₂ concentration (73% CO₂). In contrast to the visible inhibitory effects on the CSSEPs, subjective ratings of the test stimulus did not reflect CPM action.

Discussion: The experimental pain model using CO₂ stimuli to elicit CSSEPs proved to be sensitive enough to capture weak CPM effects elicited by a conditioning stimulus of rather low noxious load. The usage of such mild noxious conditioning stimuli—in contrast to stimuli of higher noxious load (e.g., cold pressor test)—has the advantage that the activation of other types of pain inhibitory mechanisms in parallel (like attentional distraction, stress-induced analgesia) can be avoided.     

Low representation of Fc receptor-like 1–5 molecules in leukemic cells from Iranian patients with acute lymphoblastic leukemia

Recent studies have demonstrated expression of Fc receptor-like (FCRL) molecules, a newly identified family with preferential B-cell lineage expression, in some chronic B-cell leukemias with possible implication for classification and/or targeted immunotherapy. In this study, the expression pattern of FCRL1-5 genes was studied in 73 Iranian ALL patients and 35 normal subjects using semi-quantitative RT-PCR method. FCRL protein expression was also investigated by flow cytometry. Our results indicate significant down-regulation of all FCRL genes in ALL compared to normal subjects. Although, FCRL mRNA expression was almost exclusively confined to normal isolated B-cells compared to T-cells, but these genes were similarly expressed in B-ALL, T-ALL and different B-ALL immunophenotypic subtypes. Surface protein expression of FCRL1, 2, 4, and 5 molecules in 10 ALL and 5 normal samples confirmed the PCR results. Expression profile of FCRL molecules in different subtypes of ALL argues against their potential implication as suitable targets for classification and/or immunotherapy of ALL. T. Kazemi, H. Asgarian-Omran and A. Memarian have contributed equally to this study.     

The Effect of Lactobacillus casei Consumption in Improvement of Obsessive–Compulsive Disorder: an Animal Study

Obsessive–compulsive disorder (OCD) is an important neuropsychiatric disorder worldwide. Common treatments of OCD include serotonergic antidepressants, which can cause potentially serious side effects. We assessed the effects of Lactobacillus casei (L. casei) Shirota consumption in an animal model of OCD. OCD-like symptoms were induced in rats by the chronic injection of the D2/D3 dopamine agonist quinpirole hydrochloride. Rats were classified into five groups of 6 rats. Four groups were injected chronically with quinpirole (0.5 mg/kg, twice weekly for 5 weeks). They were fed with L. casei Shirota (10⁹ CF/g, daily for 4 weeks) (group 1), fluoxetine (10 mg/kg, daily for 4 weeks) (group 2), combination of L. casei Shirota and fluoxetine (group 3), and normal saline (positive control group). The last group did not receive dopamine agonist and was only injected with saline (negative control group). Expression levels of brain-derived neurotrophic factor (Bdnf), solute carrier family 6 member 4 (Slc6a4), and 5-hydroxytryptamine receptor type 2A (Htr2a) were assessed in orbitofrontal cortex tissues of all rats. Behavioral tests showed improvement of OCD signs in rats treated with L. casei Shirota, fluoxetine, and a combination of drugs. Quantitative PCR analysis showed a remarkable decrease in the expression of Bdnf and an increase in the expression of Htr2a in quinpirole-treated rats. After treatment with L. casei Shirota and fluoxetine, the expression level of Bdnf was increased remarkably, whereas Htr2a expression was decreased. The current study showed the effectiveness of L. casei Shirota in the treatment of OCD in a rat model. The beneficial effects of this probiotic are possibly exerted through the modulation of serotonin-related genes expression.

     

Polymorphism of adiponectin (45T/G) and adiponectin receptor-2 (795G/A) in an Iranian population: relation with insulin resistance and response to treatment with pioglitazone in patients with type 2 diabetes mellitus

Adiponectin, an adipose-derived plasma protein, is reduced in patients with obesity and type 2 diabetes. Thiazolidinediones can increase adiponectin levels and improve insulin sensitivity. This study investigated the associations between type 2 diabetes and two single-nucleotide polymorphisms in the adiponectin (45T/G) and adiponectin receptor-2 gene (795G/A), and investigated whether these genetic variants affect the response to pioglitazone in Iranian patients with type 2 diabetes. We genotyped 128 non-diabetic participants and 101 patients with type 2 diabetes for 45T/G and 795G/A with polymerase chain reaction-restriction fragment length polymorphism assays. Patients were treated with pioglitazone for 12 weeks, after which we compared laboratory parameters in these two groups. Fasting blood sugar differed significantly in individuals with different 795G/A genotypes after pioglitazone treatment (P = 0.009). The mean decrease in insulin/glucose ratio after treatment also differed significantly in individuals with different 45T/G genotypes (P = 0.035). The T allele frequency for 45T/G was 87.11% in controls versus 81.68% in patients (P = 0.071). The TG and GG genotypes were more frequent in patients (P = 0.032). The G allele frequency for 795G/A was 76.17% in controls versus 80.20% in patients (P = 0.179). 795G/A variants were not significantly different between patient and control group. The adiponectin gene 45T/G mutation may be an important determinant of type 2 diabetes in the Iranian population. However, adiponectin 45T/G and adiponectin receptor-2 795G/A polymorphisms were not significantly associated with the response to pioglitazone in our sample.     

Synthesis and characterization of modified starch hydrogels for photodynamic treatment of cancer

The objective of the present study was to develop carboxymethyl starch (CMS) and dextran sulfate (DS) hydrogels that are able to efficiently encapsulate 5-,10-,15-,20-tetrakis(meso-hydroxyphenyl)porphyrin (mTHPP), a porphyrin-based PS agent. The study showed that the lifetime of the triplet state for porphyrin PS is significantly increase when encapsulate into hydrogel. In addition to the possible enhancement of (1)O(2) generation, other advantages to incorporating porphyrin-based PS agents into hydrogel include the ability to solubilize these generally hydrophobic agents, the small and uniform size of hydrogels, and potential for passive targeting of solid tumors via the enhanced permeation and retention effect decreasing systemic photosensitization. This novel type of carboxymethyl starch (CMS) hydrogel using dextran sulfate (DS) as a polyanionic polymer was developed to achieve complex coacervation for the incorporation and controlled release of an anti-angiogenesis hexapeptide, this was the first report describing the use of DS to formulate CMS based hydrogels.     

Sodium butyrate inhibits angiogenesis of human intestinal microvascular endothelial cells through COX-2 inhibition

We examined the effect of sodium butyrate on in vitro angiogenesis and cyclooxygenase (COX) expression using primary cultures of human intestinal microvascular endothelial cells (HIMEC). Butyrate inhibited VEGF-induced cellular proliferation, transmigration and tube formation of HIMEC. Butyrate also inhibited COX-2 expression as well as prostaglandin (PG)E2 and PGI2 production, and administration of PGI2 analog partially reversed the effect of butyrate on HIMEC angiogenesis. These results indicate that sodium butyrate inhibits HIMEC angiogenesis through down-regulation of COX-2 expression and PG production, and suggest that anti-angiogenic mechanisms may also be involved in the inhibitory effect of sodium butyrate on tumor growth.