The benefit of directly comparing autism and schizophrenia for revealing mechanisms of social cognitive impairment

Autism and schizophrenia share a history of diagnostic conflation that was not definitively resolved until the publication of the DSM-III in 1980. Though now recognized as heterogeneous disorders with distinct developmental trajectories and dissociative features, much of the early nosological confusion stemmed from apparent overlap in certain areas of social dysfunction. In more recent years, separate but substantial literatures have accumulated for autism and schizophrenia demonstrating that abnormalities in social cognition directly contribute to the characteristic social deficits of both disorders. The current paper argues that direct comparison of social cognitive impairment can highlight shared and divergent mechanisms underlying pathways to social dysfunction, a process that can provide significant clinical benefit by informing the development of tailored treatment efforts. Thus, while the history of diagnostic conflation between autism and schizophrenia may have originated in similarities in social dysfunction, the goal of direct comparisons is not to conflate them once again but rather to reveal distinctions that illuminate disorder-specific mechanisms and pathways that contribute to social cognitive impairment

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Nuclear Localization Sequences in Cytomegalovirus Capsid Assembly Proteins (UL80 Proteins) Are Required for Virus Production: Inactivating NLS1, NLS2, or Both Affects Replication to Strikingly Different Extents▿

Scaffolding proteins of spherical prokaryotic and eukaryotic viruses have critical roles in capsid assembly. The primary scaffolding components of cytomegalovirus, called the assembly protein precursor (pAP, pUL80.5) and the maturational protease precursor (pPR, pUL80a), contain two nuclear localization sequences (NLS1 and NLS2), at least one of which is required in coexpression experiments to translocate the major capsid protein (MCP, pUL85) into the nucleus. In the work reported here, we have mutated NLS1 and NLS2, individually or together, in human cytomegalovirus (HCMV, strain AD169) bacmid-derived viruses to test their effects on virus replication. Consistent with results from earlier transfection/coexpression experiments, both single-mutant bacmids gave rise to infectious virus but the double mutant did not. In comparisons with the wild-type virus, both mutants showed slower cell-to-cell spread; decreased yields of infectious virus (3-fold lower for NLS1− and 140-fold lower for NLS2−); reduced efficiency of pAP, pPR, and MCP nuclear translocation (sixfold lower for NLS1− and eightfold lower for NLS2−); increased amounts of a 120-kDa MCP fragment; and reduced numbers of intranuclear capsids. All effects were more severe for the NLS2− mutant than the NLS1− mutant, and a distinguishing feature of cells infected with the NLS2− mutant was the accumulation of large, UL80 protein-containing structures within the nucleus. We conclude that these NLS assist in the nuclear translocation of MCP during HCMV replication and that NLS2, which is unique to the betaherpesvirus UL80 homologs, may have additional involvements during replication

Cleavage of Human Cytomegalovirus Protease pUL80a at Internal and Cryptic Sites Is Not Essential but Enhances Infectivity

The cytomegalovirus (CMV) maturational protease, assemblin, contains an “internal” (I) cleavage site absent from its homologs in other herpesviruses. Blocking this site for cleavage did not prevent replication of the resulting I(−) mutant virus. However, cells infected with the I(−) virus showed increased amounts of a fragment produced by cleavage at the nearby “cryptic” (C) site, suggesting that its replication may bypass the I-site block by using the C site as an alternate cleavage pathway. To test this and further examine the biological importance of these cleavages, we constructed two additional virus mutants—one blocked for C-site cleavage and another blocked for both I- and C-site cleavage. Infectivity comparisons with the parental wild-type virus showed that the I(−) mutant was the least affected for virus production, whereas infectivity of the C(−) mutant was reduced by ≈40% and when both sites were blocked virus infectivity was reduced by nearly 90%, providing the first evidence that these cleavages have biological significance. We also present and discuss evidence suggesting that I-site cleavage destabilizes assemblin and its fragments, whereas C-site cleavage does not

High-Molecular-Weight Protein (pUL48) of Human Cytomegalovirus Is a Competent Deubiquitinating Protease: Mutant Viruses Altered in Its Active-Site Cysteine or Histidine Are Viable

We show here that the high-molecular-weight protein (HMWP or pUL48; 253 kDa) of human cytomegalovirus (HCMV) is a functionally competent deubiquitinating protease (DUB). By using a suicide substrate probe specific for ubiquitin-binding cysteine proteases (DUB probe) to screen lysates of HCMV-infected cells, we found just one infected-cell-specific DUB. Characteristics of this protein, including its large size, expression at late times of infection, presence in extracellular virus particles, and reactivity with an antiserum to the HMWP, identified it as the HMWP. This was confirmed by constructing mutant viruses with substitutions in two of the putative active-site residues, Cys24Ile and His162Ala. HMWP with these mutations either failed to bind the DUB probe (C24I) or had significantly reduced reactivity with it (H162A). More compellingly, the deubiquitinating activity detected in wild-type virus particles was completely abolished in both the C24I and H162A mutants, thereby directly linking HMWP with deubiquitinating enzyme activity. Mutations in these active-site residues were not lethal to virus replication but slowed production of infectious virus relative to wild type and mutations of other conserved residues. Initial studies, by electron microscopy, of cells infected with the mutants revealed no obvious differences at late times of replication in the general appearance of the cells or in the distribution, relative numbers, or appearance of virus particles in the cytoplasm or nucleus

Assembly Protein Precursor (pUL80.5 Homolog) of Simian Cytomegalovirus Is Phosphorylated at a Glycogen Synthase Kinase 3 Site and Its Downstream “Priming” Site: Phosphorylation Affects Interactions of Protein with Itself and with Major Capsid Protein

Capsid assembly among the herpes-group viruses is coordinated by two related scaffolding proteins. In cytomegalovirus (CMV), the main scaffolding constituent is called the assembly protein precursor (pAP). Like its homologs in other herpesviruses, pAP is modified by proteolytic cleavage and phosphorylation. Cleavage is essential for capsid maturation and production of infectious virus, but the role of phosphorylation is undetermined. As a first step in evaluating the significance of this modification, we have identified the specific sites of phosphorylation in the simian CMV pAP. Two were established previously to be adjacent serines (Ser156 and Ser157) in a casein kinase II consensus sequence. The remaining two, identified here as Thr231 and Ser235, are within consensus sequences for glycogen synthase kinase 3 (GSK-3) and mitogen-activated protein kinase, respectively. Consistent with Thr231 being a GSK-3 substrate, its phosphorylation required a downstream “priming” phosphate (i.e., Ser235) and was reduced by a GSK-3-specific inhibitor. Phosphorylation of Ser235 converts pAP to an electrophoretically slower-mobility isoform, pAP*; subsequent phosphorylation of pAP* at Thr231 converts pAP* to a still-slower isoform, pAP**. The mobility shift to pAP* was mimicked by substituting an acidic amino acid for either Thr231 or Ser235, but the shift to pAP** required that both positions be phosphorylated. Glu did not substitute for pSer235 in promoting phosphorylation of Thr231. We suggest that phosphorylation of Thr231 and Ser235 causes charge-driven conformational changes in pAP, and we demonstrate that preventing these modifications alters interactions of pAP with itself and with major capsid protein, suggesting a functional significance