Immunohistochemical localization of phosphohistidine phosphatase PHPT1 in mouse and human tissues

Protein histidine phosphorylation accounts for about 6% of the total protein phosphorylation in eukaryotic cells; still details concerning histidine phosphorylation and dephosphorylation are limited. A mammalian 14-kDa phosphohistidine phosphatase, also denominated PHPT1, was found 6 years ago that provided a new tool in the study of phosphohistidine phosphorylation. The localization of PHPT1 mRNA by Northern blot analysis revealed high expression in heart and skeletal muscle. The main object of the present study was to determine the PHPT1 expression on protein level in mouse tissues in order to get further information on the physiological role of the enzyme. Tissue samples from adult mice and 14.5-day-old mouse embryos were processed for immunostaining using a PHPT1-specific polyclonal antibody. The same antibody was also provided to the Swedish human protein atlas project (HPR) (http://www.proteinatlas.org/index.php). The results from both studies were essentially consistent with the previously reported expression of mRNA of a few human tissues. In addition, several other tissues, including testis, displayed a high protein expression. A salient result of the present investigation was the ubiquitous expression of the PHPT1 protein and its high expression in continuously dividing epithelial cells

Prevalence and Function of Non-Suicidal Self-Injury (NSSI) in a Community Sample of Adolescents, Using Suggested DSM-5 Criteria for a Potential NSSI Disorder

Previous prevalence rates of non-suicidal self-injury(NSSI) in adolescents have varied considerably. In the present cross-sectional study, prevalence rates, characteristics and functions of NSSI were assessed in a large randomized community sample consisting of 3,060 (50.5 % female) Swedish adolescents aged 15–17 years. The suggested criteria for NSSI disorder in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) were used to assess prevalence rates with the aim of arriving at a more precise estimate. Out of the whole sample, 1,088 (35.6 %) adolescents (56.2 % female) reported at least one episode of NSSI during the last year, of which 205 (6.7 %) met suggested DSM-5 criteria for a potential NSSI disorder diagnosis. The NSSI disorder diagnosis was significantly more common in girls (11.1 % vs. 2.3 %, χ2 (1, N=3046) = 94.08, p<0.001, cOR=5.43, 95 % CI [3.73, 7.90]). The NSSI disorder group consisted of significantly more smokers and drug users compared to adolescents with NSSI that did not meet DSM-5 criteria for NSSI disorder, and also differed concerning demographic variables. A confirmatory factor analysis (CFA) was conducted on reported functions of NSSI, with the aim of validating Nock and Prinstein’s (Journal of Consulting and Clinical Psychology 72:885–890, 2004, Journal of Abnormal Psychology 114:140–146, 2005) four-factor model on a Swedish community sample, resulting in a close to acceptable fit. A two-factor model (social and automatic reinforcement) resulted in a slightly better fit. The most frequently reported factors were positive and negative automatic reinforcement. A majority of functions were significantly more often reported by girls than boys. The implications of the suggested DSM-5 criteria and reported functions are discussed

Measurement and stratification of nonsuicidal self-injury in adolescents

Abstract Background Nonsuicidal self-injury (NSSI) is highly prevalent in adolescents. In survey and interview studies assessing NSSI, methods of assessment have been shown to influence prevalence estimates. However, knowledge of which groups of adolescents that are identified with different measurement methods is lacking, and the characteristics of identified groups are yet to be investigated. Further, only a handful of studies have been carried out using exploratory methods to identify subgroups among adolescents with NSSI. Methods The performance of two prevalence measures (single-item vs. behavioral checklist) in the same cross-sectional community sample (n = 266, age M = 14.21, 58.3% female) of adolescents was compared regarding prevalence estimates and also characterization of the identified groups with lifetime NSSI prevalence. A cluster analysis was carried out in the same sample. Identified clusters were compared to the two groups defined using the prevalence measures. Results A total of 118 (44.4%) participants acknowledged having engaged in NSSI at least once. Of these, a group of 55 (20.7%) adolescents confirmed NSSI on a single item and 63 (23.7%) adolescents confirmed NSSI only on a behavioral checklist, while denying NSSI on the single item. Groups differed significantly, with the single-item group being more severely affected and having higher mean scores on difficulties in emotion regulation, self-criticism, number of methods, higher frequency of NSSI, higher rates of suicidal ideation and suicidal behavior and lower mean score on health-related quality of life. All cases with higher severity were not identified by the single-item question. Cluster analysis identified three clusters, two of which fit well with the groups identified by single-item and behavioral checklist measures. Conclusions When investigating NSSI prevalence in adolescents, findings are influenced by the researchers’ choice of measures. The present study provides some directions toward what kind of influence to expect given the type of measure used, both with regards to the size of the identified group and its composition. Implications for future research as well as clinical and preventive work are discussed

Identification and characterization of a mammalian 14-kDa phosphohistidine phosphatase

Protein histidine phosphorylation in eukaryotes has beensparsely studied compared to protein serine/threonine andtyrosine phosphorylation. In an attempt to rectify this byprobing porcine liver cytosol with the phosphohistidinecontainingpeptide succinyl-Ala-His(P)-Pro-Phe-p-nitroanilide(phosphopeptide I), we observed a phosphataseactivity that was insensitive towards okadaic acid andEDTA. This suggested the existence of a phosphohistidinephosphatase different from protein phosphatase 1, 2Aand 2C. A 1000-fold purification to apparent homogeneitygave a 14-kDa phosphatase with a specific activity of 3lmolÆmin)1Æmg)1 at pH 7.5 with 7 lM phosphopeptide Ias substrate. Partial amino-acid sequence determination ofthe purified porcine enzyme by MS revealed similaritywith a human sequence representing a human chromosome9 gene of hitherto unknown function. Molecularcloning from a human embryonic kidney cell cDNAlibraryfollowed by expression and purification, yielded aprotein with a molecular mass of 13 700 Da, and anEDTA-insensitive phosphohistidine phosphatase activityof 9 lmolÆmin)1Æmg)1 towards phosphopeptide I. Nodetectable activity was obtained towards a set of phosphoserine-,phosphothreonine-, and phosphotyrosine peptides.Northern blot analysis indicated that the humanphosphohistidine phosphatase mRNA was present preferentiallyin heart and skeletal muscle. These resultsprovide a new tool for studying eukaryotic histidinephosphorylation/dephosphorylation