Possible etiologies of increased incidence of gastroschisis.

PURPOSE: Gastroschisis incidence has increased over the past decade nationally and in Hawaii. Pesticides have been implicated as potential causative factors for gastroschisis, and use of restricted use pesticides (RUPs) is widespread in Hawaii. This study was conducted to characterize gastroschisis cases in Hawaii and determine whether RUP application correlates with gastroschisis incidence. METHODS: Gastroschisis patients treated in Hawaii between September, 2008 and August, 2015 were mapped by zip code along with RUP use. Spatial analysis software was used to identify patients' homes located within the pesticide application zone and agricultural land use areas. RESULTS: 71 gastroschisis cases were identified. 2.8% of patients were from Kauai, 64.8% from Oahu, 16.9% from Hawaii, 14.1% from Maui, and 1.4% from Molokai. RUPs have been used on all of these islands. 78.9% of patients lived in zip codes overlapping agricultural land use areas. 85.9% of patients shared zip codes with RUP-use areas. CONCLUSION: The majority of gastroschisis patients were from RUP-use areas, supporting the idea that pesticides may contribute to the development of gastroschisis, although limited data on specific releases make it difficult to apply these findings. As more RUP-use data become available to the public, these important research questions can be investigated further.

Global analysis of protein palmitoylation in African trypanosomes.

Many eukaryotic proteins are posttranslationally modified by the esterification of cysteine thiols to long-chain fatty acids. This modification, protein palmitoylation, is catalyzed by a large family of palmitoyl acyltransferases that share an Asp-His-His-Cys Cys-rich domain but differ in their subcellular localizations and substrate specificities. In Trypanosoma brucei, the flagellated protozoan parasite that causes African sleeping sickness, protein palmitoylation has been observed for a few proteins, but the extent and consequences of this modification are largely unknown. We undertook the present study to investigate T. brucei protein palmitoylation at both the enzyme and substrate levels. Treatment of parasites with an inhibitor of total protein palmitoylation caused potent growth inhibition, yet there was no effect on growth by the separate, selective inhibition of each of the 12 individual T. brucei palmitoyl acyltransferases. This suggested either that T. brucei evolved functional redundancy for the palmitoylation of essential palmitoyl proteins or that palmitoylation of some proteins is catalyzed by a noncanonical transferase. To identify the palmitoylated proteins in T. brucei, we performed acyl biotin exchange chemistry on parasite lysates, followed by streptavidin chromatography, two-dimensional liquid chromatography-tandem mass spectrometry protein identification, and QSpec statistical analysis. A total of 124 palmitoylated proteins were identified, with an estimated false discovery rate of 1.0%. This palmitoyl proteome includes all of the known palmitoyl proteins in procyclic-stage T. brucei as well as several proteins whose homologues are palmitoylated in other organisms. Their sequences demonstrate the variety of substrate motifs that support palmitoylation, and their identities illustrate the range of cellular processes affected by palmitoylation in these important pathogens.

Identification of a palmitoyl acyltransferase required for protein sorting to the flagellar membrane.

Protein palmitoylation has diverse effects in regulating protein membrane affinity, localization, binding partner interactions, turnover and function. Here, we show that palmitoylation also contributes to the sorting of proteins to the eukaryotic flagellum. African trypanosomes are protozoan pathogens that express a family of unique Ca(2+)-binding proteins, the calflagins, which undergo N-terminal myristoylation and palmitoylation. The localization of calflagins depends on their acylation status. Myristoylation alone is sufficient for membrane association, but, in the absence of palmitoylation, the calflagins localize to the pellicular (cell body) membrane. Palmitoylation, which is mediated by a specific palmitoyl acyltransferase, is then required for subsequent trafficking of calflagin to the flagellar membrane. Coincident with the redistribution of calflagin from the pellicular to the flagellar membrane is their association with lipid rafts, which are highly enriched in the flagellar membrane. Screening of candidate palmitoyl acyltranferases identified a single enzyme, TbPAT7, that is necessary for calflagin palmitoylation and flagellar membrane targeting. Our results implicate protein palmitoylation in flagellar trafficking, and demonstrate the conservation and specificity of palmitoyl acyltransferase activity by DHHC-CRD proteins across kingdoms.