Inherited SLP76 deficiency in humans causes severe combined immunodeficiency, neutrophil and platelet defects.

The T cell receptor (TCR) signaling pathway is an ensemble of numerous proteins that are crucial for an adequate immune response. Disruption of any protein involved in this pathway leads to severe immunodeficiency and unfavorable clinical outcomes. Here, we describe an infant with severe immunodeficiency who was found to have novel biallelic mutations in SLP76. SLP76 is a key protein involved in TCR signaling and in other hematopoietic pathways. Previous studies of this protein were performed using Jurkat-derived human leukemic T cell lines and SLP76-deficient mice. Our current study links this gene, for the first time, to a human immunodeficiency characterized by early-onset life-threatening infections, combined T and B cell immunodeficiency, severe neutrophil defects, and impaired platelet aggregation. Hereby, we characterized aspects of the patient's immune phenotype, modeled them with an SLP76-deficient Jurkat-derived T cell line, and rescued some consequences using ectopic expression of wild-type SLP76. Understanding human diseases due to SLP76 deficiency is helpful in explaining the mixed T cell and neutrophil defects, providing a guide for exploring human SLP76 biology.

Inverse association between 1,5-anhydroglucitol and neonatal diabetic complications.

PURPOSE: A glycemic control marker to predict neonatal diabetic complications is unavailable. We aimed to examine if 1,5-anhydroglucitol (1,5-AG) can predict neonatal complications in women with diabetes in pregnancy. METHODS: Prospective observational study from December 2011 to August 2013. We recruited 105 women, 70 diabetic (gestational and pregestational) and 35 nondiabetic. 1,5-AG at birth was compared between the two groups. In the diabetic group 1,5-AG, HbA1c, and fructosamine were measured before glycemic control initiation (first visit), after 4-6 weeks (second visit), and at delivery. Women were divided to poor (1,5-AG values below median at birth) and good (1,5-AG values at median and above) glycemic control groups. Mean daily glucose charts were collected. The primary outcome was a composite of neonatal diabetic complications: respiratory distress, hypoglycemia, polycythemia, hyperbilirubinemia, and large for gestational age. RESULTS: Mean 1,5-AG in the nondiabetic group was similar to that of the diabetic group without the composite outcome and was significantly higher than in the diabetic group with the composite outcome. The rate of the composite outcome was higher in the poor glycemic control group compared with the good glycemic control group (adjusted odds ratio (OR) 3.8 95% CI [1.2-12.3]). Only 1,5-AG was inversely associated with the composite outcome at all time points; the second visit was the only independent risk factor in multivariable logistic regression (OR 0.7 95% CI 0.54-0.91). The rest of the glycemic markers were not associated with neonatal composite outcome. CONCLUSIONS: 1,5-AG is inversely associated with neonatal diabetic complications and is superior to other glycemic markers in predicting those complications.

Promotion of bone morphogenetic protein signaling by tetraspanins and glycosphingolipids.

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor ß (TGFß) superfamily of secreted molecules. BMPs play essential roles in multiple developmental and homeostatic processes in metazoans. Malfunction of the BMP pathway can cause a variety of diseases in humans, including cancer, skeletal disorders and cardiovascular diseases. Identification of factors that ensure proper spatiotemporal control of BMP signaling is critical for understanding how this pathway is regulated. We have used a unique and sensitive genetic screen to identify the plasma membrane-localized tetraspanin TSP-21 as a key new factor in the C. elegans BMP-like "Sma/Mab" signaling pathway that controls body size and postembryonic M lineage development. We showed that TSP-21 acts in the signal-receiving cells and genetically functions at the ligand-receptor level. We further showed that TSP-21 can associate with itself and with two additional tetraspanins, TSP-12 and TSP-14, which also promote Sma/Mab signaling. TSP-12 and TSP-14 can also associate with SMA-6, the type I receptor of the Sma/Mab pathway. Finally, we found that glycosphingolipids, major components of the tetraspanin-enriched microdomains, are required for Sma/Mab signaling. Our findings suggest that the tetraspanin-enriched membrane microdomains are important for proper BMP signaling. As tetraspanins have emerged as diagnostic and prognostic markers for tumor progression, and TSP-21, TSP-12 and TSP-14 are all conserved in humans, we speculate that abnormal BMP signaling due to altered expression or function of certain tetraspanins may be a contributing factor to cancer development.