Hsp40 regulates the amount of keratin proteins via ubiquitin-proteasome pathway in cultured human cells

Keratins represent important structural components of intermediate filament proteins. Their expression profiles are remarkably tissue-specific. Recent data have shown that keratins associate with many proteins including heat shock proteins (HSP). We recently identified cell-specific keratin and HSP expression. We aimed to gain further insight into the regulation of keratins by specific inhibition through knockdown of Hsp40 in human keratinocyte cells. Keratin-HSP interaction in HaCaT cell lysate was evaluated by immunoprecipitation followed by Western blotting. Immunofluorescence, was used to examine the co-localization of keratins and Hsp40. Hsp40 depletion led to an increase in the levels of keratin proteins (K5, K14, K10) and a decrease in keratin ubiquitination without influencing keratin gene expression. Our results demonstrate direct or indirectly association of Hsp40 and imply that expressed keratin proteins were regulated by Hsp40 depending on the ubiquitin-proteasome pathway in HaCaT. Furthermore, the K10 differentiation marker was increased by knockdown of Hsp40. The results presented in this study indicate that Hsp40 is related to the differentiation exchange of keratin pairs.     

Impaired cliff avoidance reaction in dopamine transporter knockout mice

Rationale

Impulsivity is a key feature of disorders that include attention-deficit/hyperactivity disorder (ADHD). The cliff avoidance reaction (CAR) assesses maladaptive impulsive rodent behavior. Dopamine transporter knockout (DAT-KO) mice display features of ADHD and are candidates in which to test other impulsive phenotypes.

Objectives

Impulsivity of DAT-KO mice was assessed in the CAR paradigm. For comparison, attentional deficits were also assessed in prepulse inhibition (PPI) in which DAT-KO mice have been shown to exhibit impaired sensorimotor gating.

Results

DAT-KO mice exhibited a profound CAR impairment compared to wild-type (WT) mice. As expected, DAT-KO mice showed PPI deficits compared to WT mice. Furthermore, the DAT-KO mice with the most impaired CAR exhibited the most severe PPI deficits. Treatment with methylphenidate or nisoxetine ameliorated CAR impairments in DAT-KO mice.

Conclusion

These results suggest that DAT-KO mice exhibit impulsive CAR behavior that correlates with their PPI deficits. Blockade of monoamine transporters, especially the norepinephrine transporter (NET) in the prefrontal cortex (PFC), may contribute to pharmacological improvement of impulsivity in these mice.     

Electroconvulsive shock increases serotonin transporter in the rat frontal cortex

The antidepressive action of electroconvulsive shock (ECS) is thought to involve the alteration in serotonin (5-HT) neurotransmission, including the increase in 5-HT release and uptake. In our previous study, 5-HT transporter (5-HTT) mRNA expression was decreased after single and repetitive ECS in rat raphe nucleus. In the present study, we investigated the effects of single and repetitive ECS on the protein levels of 5-HTT in the frontal cortex, hippocampus and raphe nucleus of rat brain using quantitative Western blot analysis. Single ECS did not alter 5-HTT protein expression in any brain regions examined. Repetitive ECS stably increased 5-HTT protein in the frontal cortex, but not in the hippocampus and raphe nucleus. Because ECS is known to facilitate the release of neurotransmitters, our results suggest that the increased 5-HTT protein expression in the frontal cortex might be a compensatory change against the enhanced 5-HT release by ECS in presynaptic terminals.     

Occurrence and comparison of the expressed keratins in cultured human fibroblasts,endothelial cells and their sarcomas

Mutations of p53 and PTCH gene, two candidate tumor suppressor genes for basal cell carcinoma (BCC), were screened in 15 cases of sporadic BCCs that developed in sun-exposed skin region in a Korean population. p53 and PTCH mutations were detected at a frequency of 33 and 40%, respectively, and the mutations were predominantly UV-signature transition, C-->T transitions at dipyrimidine sites and CC-->TT tandem mutations. In both genes, the most common mutations were missense mutations resulting in amino acid substitution, which is different than the results from Caucasian BCCs where mutations are frequently predicted to make truncated or absent proteins. All mutations, except for one, occurred on the nontranscribed strand where is little efficient removal of UV-induced pyrimidine dimers relative to the transcribed strand. Loss of heterozygocity (LOH) of 9q22 for PTCH loci was found in eight of 15 informative cases of BCCs (53%), but none of the cases were informative for LOH of 17p13 for p53 loci. Not only do our data indicate the key role played by p53 and PTCH in the development of BCCs, these findings also suggest that UVB may significantly contribute to BCC tumorigenesis. Moreover, molecular epidemiology composed of incidence of p53 and PTCH mutations, difference in the type of mutation and repair bias of UV-induced DNA lesions might affect the distinct features of BCCs between different racial population.     

An Immunohistochemical Study of Sebaceous Carcinoma with Anti-Keratin Monoclonal Antibodies: Comparison with Other Skin Cancers

Formalin-fixed and paraffin-embedded tissue specimens of six cases of extraocular sebaceous carcinoma were studied immunohistochemically with eight anti-keratin monoclonal antibodies, 34βB4, 35βH11, Ks13.1, Ks19.1, PKK1, LP34, KL1 and AE1. The staining patterns of sebaceous carcinoma were compared with those of normal sebaceous glands and other skin cancers which should be distinguished from sebaceous carcinoma histopathologically. The other skin cancers compared were eccrine porocarcinoma, malignant clear cell hidradenoma, extramammary Paget's disease with underlying adenocarcinoma, malignant trichilemmoma, and squamous cell carcinoma. Most cases of sebaceous carcinoma were stained with 35βH11, Ks19.1, LP34, KL1 and AE1, while normal sebaceous glands were positive only with 35βH11, LP34, KL1 and AE1. By immunostaining, sebaceous carcinoma was distinguishable from extramammary Paget's disease with underlying adenocarcinoma, squamous cell carcinoma, malignant trichilemmoma, and eccrine porocarcinoma, but was not clearly distinguishable from malignant clear cell hidradenoma. These findings demonstrate that sebaceous carcinoma shows positive reactions with antibodies to simple epithelial keratin, probably as a result of neoplastic transformation, and that immunohistochemical examination using anti-keratin monoclonal antibodies is useful in distinguishing sebaceous carcinoma from several other skin cancers.     

Effective Medical Examination for VDT Workers Using a New Testing Method of Ocular Alignment

To investigate the relationship between asthenopia of VDT workers and the ocular alignment, we measured far and near alignment of 407 subjects (74 VDT workers with asthenopia, 137 VDT workers without asthenopia, and 196 non-VDT workers) using Total Vision tester (VT-500). There was no relationship between the asthenopia and the records of far alignment test. On the other hand, the incedence of exophoria and convergence insufficiency type in near alignment test was significantly high in the group of VDT workers with asthenopia. From these results, we speculate that cases who have exophoria or show incomplete fusional response measured under the near testing distance (50 cm) tend to complain of asthenopia.     

Association analysis of delta-opioid receptor gene polymorphisms in methamphetamine dependence/psychosis.

The role of the delta-opioid receptor (OPRD1) in methamphetamine (MAP) addiction was investigated using association analysis between OPRD1 gene polymorphisms and MAP dependence/psychosis. DNA samples from Japanese patients with MAP dependence/psychosis were analyzed to find polymorphisms in OPRD1 gene exons and exon-intron boundaries. One novel single nucleotide polymorphism (SNP) in intron 1 and two SNPs in exon 3 were identified. The two SNPs in exon 3 were in linkage disequilibrium. No significant difference was observed in either genotypic or allelic frequencies of these SNPs between controls (n = 260) and MAP dependent/psychotic patients (n = 170). Global analyses using the three SNPs and subcategory analyses on clinical parameters also showed no significant differences. These results suggest that the OPRD1 gene variants may not be a factor in vulnerability to MAP dependence/psychosis.     

Visual event-related potential in mild dementia of the Alzheimer''s type

Visual event-related potentials (ERP) and behavioral measures were recorded during a geometrical-figure discrimination task to examine sensory processing in 10 patients with mild dementia of the Alzheimer's type (DAT) and 10 age-matched controls. No difference existed between the groups in P1, N1, and P2 potentials, which reflects the early stage of sensory processing, as well as in NA potential, which reflects pattern recognition. The patients showed reduced amplitude of P3 potential, retarded reaction time, and increased behavioral errors compared to controls. These findings suggest that the patients with mild DAT were intact in early sensory processing including pattern recognition but were selectively compromised in higher-level processing, including integration of information and memory matching, which may influence behavioral deviation.     

Genetically modified animals as models for psychiatric diseases]

Animal models of mental disorders as well as physical disorders have been useful tools to elucidate pathophysiology of the complex disorders and develop new therapeutics. Transgenic mice including gene knockout animals have been produced by gene targeting technology. Monoamine system which is target of antipsychotics and antidepressants has very important roles in pathology of functional psychosis. In this review, we would like to introduce monoamine transporter knockout mice that we had generated as animal models of mental disorders including schizophrenia and drug abuse.     

Effects of angiotensin II receptor signaling during skin wound healing

The tissue angiotensin (Ang) system, which acts independently of the circulating renin Ang system, is supposed to play an important role in tissue repair in the heart and kidney. In the skin, the role of the system for wound healing has remained to be ascertained. Our study demonstrated that oral administration of selective AngII type-1 receptor (AT(1)) blocker suppressed keratinocyte re-epithelization and angiogenesis during skin wound healing in rats. Immunoprecipitation and Western blot analysis indicated the existence of AT(1) and AngII type-2 receptor (AT(2)) in cultured keratinocytes and myofibroblasts. In a bromodeoxyuridine incorporation study, induction of AT(1) signaling enhanced the incorporation into keratinocytes and myofibroblasts. Wound healing migration assays revealed that induction of AT(1) signaling accelerated keratinocyte re-epithelization and myofibroblasts recovering. In these experiments, induction of AT(2) signaling acted vice versa. Taken together, our study suggests that skin wound healing is regulated by balance of opposing signals between AT(1) and AT(2).