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The transcription factor Sox10 is genetically linked with Waardenburg syndrome 4 (WS4) in humans and the Dominant megacolon (Dom) mouse model for this disease. The pigmentary defects observed in the Dom mouse and WS4 are reminiscent of those associated with mutations in the microphthalmia (Mitf) gene, which encodes a transcription factor essential for the development of the melanocyte lineage. We demonstrate here that wild type Sox10 directly binds and activates transcription of the MITF promoter, whereas a mutant form of the Sox10 protein genetically linked with WS4 acts as a dominant-negative repressor of MITF expression and can reduce endogenous MITF protein levels. The ability of Sox10 to activate transcription of the MITF promoter implicates Sox10 in the regulation of melanocyte development and provides a molecular basis for the hypopigmentation and deafness associated with WS4.

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Cysteine351 is the site for pertussis toxin-catalyzed ADP-ribosylation in the G protein Gi1 alpha. Alteration of this residue, or the equivalent cysteine in other Gi-family G proteins, has been used to examine specific interactions between receptors and these G proteins. However, no systematic analysis has been performed to determine the quantitative effect of such alterations. To address this we mutated cysteine351 of Gi1 alpha to all other possible amino acids. Each of the G protein mutants was transiently coexpressed along with the porcine alpha 2A-adrenoceptor in HEK 293/T cells. Following pertussis toxin treatment of the cells, membranes were prepared and the capacity of the agonist UK14304 to stimulate the binding of [35S]GTP gamma S to the modified G proteins was measured. A spectrum of function was observed. The presence of either a charged amino acid or a proline at this position essentially attenuated agonist regulation. The wild-type G protein did not result in maximal stimulation by agonist. The presence of certain branched chain aliphatic amino acids or bulky aromatic R groups at amino acid351 resulted in substantially greater maximal stimulation by the alpha 2A-adrenoceptor than that achieved with the wild-type sequence. The degree of activation of the forms of Gi1 alpha correlated strongly with the octanol/water partition coefficient of the amino acid at residue351. Variation in EC50 values for agonist-induced stimulation of binding of [35S]GTP gamma S to the mutant G proteins also correlated with the octanol/water partition coefficient. These results define a central role for hydrophobicity of this residue in defining productive receptor-G protein interactions.

Introduction: Recently, significant interest from families and healthcare providers has arisen to use blenderized tube feedings (BTF). Although many institutions are providing this nutritional option, literature documenting outcomes and safety is lacking. Methods: A retrospective chart review was performed on pediatric patients receiving BTF at Rutgers-Robert Wood Johnson University Hospital between January 2013 and April 2017. Demographic data and dietary information before and after BTF were collected. Reasons for diet initiation, symptoms, and anthropometrics were recorded. Adverse events and outcomes were assessed through physician documentation and relevant medication changes. Results: Thirty-five patients (24 boys) received BTF. Age at initiation of BTF ranged from 1 to 19 years (mean 8.3 +/− 5.8 [SD] years). Length of follow-up ranged from 1 to 45 months (mean 15 +/− 12.2 months). The most common reason for starting BTF was gastroesophageal reflux disease (GERD) (N = 32). Almost all patients were on medications for GERD, constipation, or gastrointestinal dysmotility before starting BTF (N = 33). Majority of patients had improvement in relevant symptoms (N = 20); 13 of 33 patients on gastrointestinal medications were able to wean or stop medication(s). BMI z scores did not differ before and after BTF initiation (P = 0.558). No serious life-threatening adverse events were found. Conclusions: Our data suggest that BTF is a safe dietary intervention that may improve gastrointestinal symptoms in pediatric patients. Further prospective studies are needed to compare safety and efficacy of BTF and commercial formulas in pediatric patients.

The alpha2A-adrenoceptor is the prototypic example of the family of G-protein-coupled receptors which function by activation of 'Gi-like' pertussis toxin-sensitive G-proteins. A number of members of this subfamily of G-proteins are often co-expressed in a single cell type. To examine the interaction of this receptor with individual Gi-family G-proteins the porcine alpha2A-adrenoceptor was transiently transfected into COS-7 cells either alone or with each of wild-type Gi1alpha, Gi2alpha and Gi3alpha or mutations of each of these G-proteins in which the cysteine residue which is the target for pertussis toxin-catalysed ADP-ribosylation was exchanged for a glycine residue. The alpha2-adrenoceptor agonist UK14304 stimulated both high-affinity GTPase activity and the binding of guanosine 5'-[gamma-35thio]-triphosphate (GTP[35S]), when expressed without any additional G-protein. These effects were greatly reduced by pretreatment of the cells with pertussis toxin. Co-expression of each of the wild-type Gi-like G-protein alpha-subunits resulted in enhanced agonist activation of the cellular G-protein population which was fully prevented by pretreatment with pertussis toxin. Co-expression of the receptor along with the cysteine-to-glycine mutations of Gi1alpha, Gi2alpha and Gi3alpha resulted in agonist stimulation of these G-proteins, which was as great as that of the wild type proteins, but now the agonist stimulation produced over that due to the activation of endogenously expressed Gi-like G-proteins was resistant to pertussis toxin treatment. The Cys --> Gly mutations of Gi1alpha, Gi2alpha and Gi3alpha were each also able to limit agonist-mediated stimulation of adenylate cyclase activity. The degree of agonist-mediated activation of the pertussis toxin-resistant mutant of Gi1alpha was correlated highly both with the level of expression of this G-protein and with the level of expression of the alpha2A-adrenoceptor. Half-maximal stimulation of high-affinity GTPase activity of the Cys --> Gly mutants of Gi1alpha, Gi2alpha and Gi3alpha required 10-15-fold higher concentrations of agonist than did stimulation of their wild-type counterparts, consistent with a model in which the affinity of functional interactions of the alpha2A-adrenoceptor with the wild-type G-protein is greater than with the pertussis toxin-resistant mutant G-protein.

The human 5-HT,, serotonin receptor has been cloned. As with the mouse and rat 5-HT,, receptors, the gene consists of two coding exons separated by a large intron. The deduced amino acid sequence of the gene reveals a protein of 357 residues which shares 93% (nucleotide) and 84% (amino acid) identity to the cloned mouse 5-HT,, receptor. We have determined the tissue distribution of the receptor by reverse transcriptase-PCR and found expression in all regions of the brain examined with little or no expression in peripheral tissues. The receptor has been transiently expressed in Cos M6 cells and exhibits a pharmacological profile closely resembling the mouse and rat 5-HT,, receptors with high, specific binding for ergotamine and methiothepin.

Melatonin exerts strong anti-tumour activity via several mechanisms, including anti-proliferative and pro-apoptotic effects in addition to its potent antioxidant activity. Several studies have investigated the effects of melatonin on haematological malignancies. However, the previous studies investigating lymphoid malignancies have been largely restricted to a single type of malignancy, Burkitt's lymphoma (BL). Thus, we examined the actions of melatonin on the growth and apoptosis in a small panel of cell lines representing different human lymphoid malignancies including Ramos (Epstein-Barr virus-negative BL), SU-DHL-4 (diffuse large B cell lymphoma), DoHH2 (follicular B non-Hodgkin lymphoma) and JURKAT (acute T cell leukaemia). We showed that melatonin promotes cell cycle arrest and apoptosis in all these cells, although there was marked variations in responses among different cell lines (sensitivity; Ramos/DoHH2 > SU-DHL-4 > JURKAT). Melatonin-induced apoptosis was relatively rapid, with increased caspase 3 and PARP cleavage detected within 0.5-1 h following melatonin addition. Moreover, there was evidence for rapid processing of both caspase 9, as well as a breakdown of the mitochondrial inner transmembrane potential. On the contrary, caspase activation was detected only in SU-DHL-4 and Ramos cells following melatonin treatment suggesting that the extrinsic pathway does not make a consistent contribution to melatonin-induced apoptosis in malignant lymphocytes. Although all cell lines expressed the high-affinity melatonin receptors, MT1 and MT2, melatonin-induced caspase activation appeared to be independent these receptors. Our findings confirm that melatonin could be a potential chemotherapeutic/preventive agent for malignant lymphocytes. However, it is necessary to take into account that different lymphoid malignancies may differ in their response to melatonin.