Degranulation and shrinkage of dark cells in eccrine glands and elevated serum carcinoembryonic antigen in patients with acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) is characterized by anhidrosis/hypohidrosis without other autonomic and neurological dysfunctions. Pathologically, AIGA is considered to usually present no significant morphological alterations in eccrine glands, the secretory portion which consists of clear cells, dark cells, and myoepithelial cells. AIGA patients recently have been reported to show high serum concentrations of carcinoembryonic antigen (CEA).

OBJECTIVE

Our aim is to reveal morphological abnormalities of dark cells and investigate their relationship with serum CEA.

METHODS

We performed comparative analysis of eccrine glands between sweat-preserved and non-sweating skin in four AIGA patients. Serum CEA concentrations in 22 cases with AIGA were measured with healthy volunteers. Furthermore, we semiquantitatively investigated dermcidin, FoxA1 and CEA expression in eccrine glands of 12 cases with AIGA and 5 cases with non-AIGA.

RESULTS

Marked degranulation and shrinkage of dark cells consistently occurred in AIGA. Furthermore, high serum CEA concentrations were found in 14 of 22 AIGA patients (over 60%), but serum CEA levels were not correlated with CEA expression in eccrine glands. Dermcidin expression in dark cells apparently decreased in AIGA patients, severely in those with high serum CEA and moderately in those with low serum CEA, while well-preserved expression was found in non-AIGA subjects.

CONCLUSION

Our study suggests morphological damage and molecular dysregulation of dark cells, leading to impairment of their functions in AIGA patients. Severely damaged dark cells correspond to high serum CEA. Accordingly, these pathological changes in eccrine dark cells may be involved in anhidrosis/hypohidrosis of AIGA.

Rac1 switching at the right time and location is essential for Fcγ receptor-mediated phagosome formation

Lamellipodia are sheet-like cell protrusions driven by actin polymerization mainly through Rac1, a GTPase molecular switch. In Fcγ receptor-mediated phagocytosis of IgG-opsonized erythrocytes (IgG-Es), Rac1 activation is required for lamellipodial extension along the surface of IgG-Es. However, the significance of Rac1 deactivation in phagosome formation is poorly understood. Our live-cell imaging and electron microscopy revealed that RAW264 macrophages expressing a constitutively active Rac1 mutant showed defects in phagocytic cup formation, while lamellipodia were formed around IgG-Es. Because the activated Rac1 reduced the phosphorylation levels of myosin light chain, failure of the cup formation were probably due to inhibition of actin/myosin II contractility. Reversible photo-manipulation of the Rac1 switch in macrophages fed with IgG-Es could phenocopy two lamellipodial motilities: outward-extension and cup-constriction by Rac1 ON and OFF, respectively. In conjunction with FRET imaging of Rac1 activity, we provide a novel mechanistic model of phagosome formation spatiotemporally controlled by Rac1 switching within a phagocytic cup.

Comparative analyses of isoforms of the calcium-independent phosphatidylethanolamine N-acyltransferase PLAAT-1 in humans and mice

N-Acylphosphatidylethanolamines (NAPEs) are a class of glycerophospholipids, which are known as precursors for different bioactive N-acylethanolamines. We previously reported that phospholipase A/acyltransferase-1 (PLAAT-1), which was originally found in mammals as a tumor suppressor, catalyzes N-acylation of phosphatidylethanolamines to form NAPEs. However, recent online database suggested the presence of an uncharacterized isoform of PLAAT-1 with an extra sequence at the N terminus. In the present study, we examined the occurrence, intracellular localization, and catalytic properties of this longer isoform, as well as the original shorter isoform from humans and mice. Our results showed that human tissues express the longer isoform but not the short isoform at all. In contrast, mice expressed both isoforms with different tissue distribution. Unlike the cytoplasmic localization of the shorter isoform, the long isoform was found in both cytoplasm and nucleus, inferring that the extra sequence harbors a nuclear localization signal. As assayed with purified proteins, neither isoform required calcium for full activity. Moreover, the overexpression of each isoform remarkably increased cellular NAPE levels. These results conclude that the new long isoform of PLAAT-1 is a calcium-independent N-acyltransferase existing in both cytoplasm and nucleus and suggest a possible formation of NAPEs in various membrane structures including nuclear membrane. J. Lipid Res 2016. 57: 2051-2060.

Invention of a novel photodynamic therapy for tumors using a photosensitizing PI3K inhibitor

XL147 (SAR245408, pilaralisib), an ATP-competitive pan-class I phosphoinositide 3-kinase (PI3K) inhibitor, is a promising new anticancer drug. We examined the effect of the PI3K inhibitor on PC3 prostate cancer cells under a fluorescence microscope and found that XL147-treated cancer cells are rapidly injured by blue wavelength (430 nm) light irradiation. During the irradiation, the cancer cells treated with 0.2-2 μM XL147 showed cell surface blebbing and cytoplasmic vacuolation and died within 15 min. The extent of cell injury/death was dependent on the dose of XL147 and the light power of the irradiation. These findings suggest that XL147 might act as a photosensitizing reagent in photodynamic therapy (PDT) for cancer. Moreover, the cytotoxic effect of photosensitized XL147 was reduced by pretreatment with other ATP-competitive PI3K inhibitors such as LY294002, suggesting that the cytotoxic effect of photosensitized XL147 is facilitated by binding to PI3K in cells. In a single-cell illumination analysis using a fluorescent probe to identify reactive oxygen species (ROS), significantly increased ROS production was observed in the XL147-treated cells when the cell was illuminated with blue light. Taken together, it is conceivable that XL147, which is preferentially accumulated in cancer cells, could be photosensitized by blue light to produce ROS to kill cancer cells. This study will open up new possibilities for PDT using anticancer drugs.

Diagnosis and treatment of bone metastasis: comprehensive guideline of the Japanese Society of Medical Oncology, Japanese Orthopedic Association, Japanese Urological Association, and Japanese Society for Radiation Oncology

Diagnosis and treatment of bone metastasis requires various types of measures, specialists and caregivers. To provide better diagnosis and treatment, a multidisciplinary team approach is required. The members of this multidisciplinary team include doctors of primary cancers, radiologists, pathologists, orthopaedists, radiotherapists, clinical oncologists, palliative caregivers, rehabilitation doctors, dentists, nurses, pharmacists, physical therapists, occupational therapists, medical social workers, etc. Medical evidence was extracted from published articles describing meta-analyses or randomised controlled trials concerning patients with bone metastases mainly from 2003 to 2013, and a guideline was developed according to the Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014. Multidisciplinary team meetings are helpful in diagnosis and treatment. Clinical benefits such as physical or psychological palliation obtained using the multidisciplinary team approaches are apparent. We established a guideline describing each specialty field, to improve understanding of the different fields among the specialists, who can further provide appropriate treatment, and to improve patients’ outcomes.

Cofilin contributes to phagocytosis of IgG-opsonized particles but not non-opsonized particles in RAW264 macrophages

Cofilin is an actin-binding protein that severs actin filaments. It plays a key role in regulating actin cytoskeletal remodeling, thereby contributing to diverse cellular functions. However, the involvement of cofilin in phagocytosis remains to be elucidated. We examined the spatiotemporal localization of cofilin during phagocytosis of IgG-opsonized erythrocytes, IgG-opsonized latex beads and non-opsonized latex beads. Live-cell imaging showed that GFP-cofilin accumulates in the sites of IgG-opsonized particle binding and in phagocytic cups. Moreover, immunofluorescence microscopy revealed that endogenous cofilin localizes to phagocytic cups engulfing IgG-opsonized particles, but not non-opsonized latex beads. Scanning electron microscopy demonstrated a notable difference in morphology between phagocytic structures in IgG-dependent and IgG-independent phagocytosis. In phagocytosis of IgG-opsonized particles, sheet-like pseudopodia extended along the surface of IgG-opsonized particles to form phagocytic cups. In contrast, in opsonin-independent phagocytosis, long finger-like filopodia captured non-opsonized latex beads. Importantly, non-opsonized beads sank into the cells without extending phagocytic cups. Our analysis of cofilin mutant expression demonstrates that phagocytosis of IgG-opsonized particles is enhanced in cells expressing wild-type cofilin or active mutant cofilin-S3A, whereas the uptake of non-opsonized latex beads is not. These data suggest that cofilin promotes actin cytoskeletal remodeling to form phagocytic cups by accelerating actin turnover and thereby facilitating phagosome formation. In contrast, cofilin is not involved in opsonin-independent phagocytosis of latex beads.

Interaction of Phospholipase A/Acyltransferase-3 with Pex19p: A POSSIBLE INVOLVEMENT IN THE DOWN-REGULATION OF PEROXISOMES

Phospholipase A/acyltransferase (PLA/AT)-3 (also known as H-rev107 or AdPLA) was originally isolated as a tumor suppressor and was later shown to have phospholipase A1/A2 activity. We have also found that the overexpression of PLA/AT-3 in mammalian cells results in specific disappearance of peroxisomes. However, its molecular mechanism remained unclear. In the present study, we first established a HEK293 cell line, which stably expresses a fluorescent peroxisome marker protein (DsRed2-Peroxi) and expresses PLA/AT-3 in a tetracycline-dependent manner. The treatment with tetracycline, as expected, caused disappearance of peroxisomes within 24 h, as revealed by diffuse signals of DsRed2-Peroxi and a remarkable decrease in a peroxisomal membrane protein, PMP70. A time-dependent decrease in ether-type lipid levels was also seen. Because the activation of LC3, a marker of autophagy, was not observed, the involvement of autophagy was unlikely. Among various peroxins responsible for peroxisome biogenesis, Pex19p functions as a chaperone protein for the transportation of peroxisomal membrane proteins. Immunoprecipitation analysis showed that PLA/AT-3 binds to Pex19p through its N-terminal proline-rich and C-terminal hydrophobic domains. The protein level and enzyme activity of PLA/AT-3 were increased by its coexpression with Pex19p. Moreover, PLA/AT-3 inhibited the binding of Pex19 to peroxisomal membrane proteins, such as Pex3p and Pex11βp. A catalytically inactive point mutant of PLA/AT-3 could bind to Pex19p but did not inhibit the chaperone activity of Pex19p. Altogether, these results suggest a novel regulatory mechanism for peroxisome biogenesis through the interaction between Pex19p and PLA/AT-3.

Small GTPases and phosphoinositides in the regulatory mechanisms of macropinosome formation and maturation

Macropinosome formation requires the sequential activation of numerous signaling pathways that coordinate the actin-driven formation of plasma membrane protrusions (ruffles) and circular ruffles (macropinocytic cups), followed by the closure of these macropinocytic cups into macropinosomes. In the process of macropinosome formation, localized productions of phosphoinositides such as PI(4,5)P₂ and PI(3,4,5)P₃ spatiotemporally orchestrate actin polymerization and rearrangement through recruiting and activating a variety of actin-associated proteins. In addition, the sequential activation of small GTPases, which are known to be master regulators of the actin cytoskeleton, plays a pivotal role in parallel with phosphoinositides. To complete macropinosome formation, phosphoinositide breakdown and Rho GTPase deactivation must occur in appropriate timings. After the nascent macropinosomes are formed, phosphoinositides and several Rab GTPases control macropinosome maturation by regulating vesicle trafficking and membrane fusion. In this review, we summarize recent advances in our understanding of the critical functions of phosphoinositide metabolism and small GTPases in association with their downstream effectors in macropinocytosis.

Rac1-dependent lamellipodial motility in prostate cancer PC-3 cells revealed by optogenetic control of Rac1 activity

The lamellipodium, an essential structure for cell migration, plays an important role in the invasion and metastasis of cancer cells. Although Rac1 recognized as a key player in the formation of lamellipodia, the molecular mechanisms underlying lamellipodial motility are not fully understood. Optogenetic technology enabled us to spatiotemporally control the activity of photoactivatable Rac1 (PA-Rac1) in living cells. Using this system, we revealed the role of phosphatidylinositol 3-kinase (PI3K) in Rac1-dependent lamellipodial motility in PC-3 prostate cancer cells. Through local blue laser irradiation of PA-Rac1-expressing cells, lamellipodial motility was reversibly induced. First, outward extension of a lamellipodium parallel to the substratum was observed. The extended lamellipodium then showed ruffling activity at the periphery. Notably, PI(3,4,5)P₃ and WAVE2 were localized in the extending lamellipodium in a PI3K-dependent manner. We confirmed that the inhibition of PI3K activity greatly suppressed lamellipodial extension, while the ruffling activity was less affected. These results suggest that Rac1-induced lamellipodial motility consists of two distinct activities, PI3K-dependent outward extension and PI3K-independent ruffling.

Development of an automated fluorescence microscopy system for photomanipulation of genetically encoded photoactivatable proteins (optogenetics) in live cells

Photomanipulation of genetically encoded light-sensitive protein activity, also known as optogenetics, is one of the most innovative recent microscopy techniques in the fields of cell biology and neurobiology. Although photomanipulation is usually performed by diverting the photobleaching mode of a confocal laser microscope, photobleaching by the laser scanning unit is not always suitable for photoactivation. We have developed a simple automated wide-field fluorescence microscopy system for the photomanipulation of genetically encoded photoactivatable proteins in live cells. An electrically automated fluorescence microscope can be controlled through MetaMorph imaging software, making it possible to acquire time-lapse, multiwavelength images of live cells. Using the journal (macro recording) function of MetaMorph, we wrote a macro program to change the excitation filter for photoactivation and illumination area during the intervals of image acquisition. When this program was run on the wide-field fluorescence microscope, cells expressing genetically encoded photoactivatable Rac1, which is activated under blue light, showed morphological changes such as lamellipodial extension and cell surface ruffling in the illuminated region. Using software-based development, we successfully constructed a fully automated photoactivation microscopy system for a mercury lamp-based fluorescence microscope.

[Results of a questionnaire on efforts to increase research-oriented doctors]

We surveyed medical and dental schools to promote the exchange of information about university efforts to increase the number of research-oriented doctors. Periods in which students rotate through laboratories to conduct research were reported by more than two thirds of universities. Many comments asserted that these efforts are effective. However, a small number of respondents reported low student motivation and insufficient time for laboratory experience. MD-PhD courses, in which students take a leave of absence in the middle of undergraduate training and follow a PhD curriculum, have been employed by more than 10 universities. However, relatively few students have chosen such programs. Modified MD-PhD courses have recently been introduced by several universities. In these courses, by taking part of the graduate school curriculum in advance, undergraduate students can shorten the time they spend in graduate school. Students who take such courses are increasing. There were many opinions that extra positions and financial support for research-oriented doctors are effective and should be enhanced. There were also many opinions that emphasize the importance of identifying research-oriented students, improving laboratory working environments, attending academic meetings and inter-university consortia to maintain students' motivation, and promoting collaboration with departments of clinical medicine.

Spatiotemporal Localization of Rab20 in Live RAW264 Macrophages during Macropinocytosis

Rab20 is a member of the Rab GTPase family, but its implication in macropinocytosis is unclear. We examined the spatiotemporal localization of Rab20 in RAW264 macrophages by the live-cell imaging of fluorescent protein-fused Rab20. It was shown that Rab20 was transiently associated with macropinosomal membranes. During the early stage of macropinosome formation, Rab20 was slightly localized on the circular ruffles (macropinocytic cups), the precursor forms of macropinosomes, and was increasingly recruited to the newly formed macropinosomes. Although Rab20 was colocalized with Rab5 and Rab21 on macropinosomal membranes, the association of Rab20 with macropinosomes persisted even after the dissociations of Rab5 and Rab21 from macropinosomal membranes. Rab20 was then colocalized with Rab7 and Lamp1, late endosomal/lysosomal markers, on macropinosomes for a while. Our data indicate that Rab20 is a novel component of macropinocytic pathway and functions at long-standing stages from early to late macropinosome maturation.

The C2A domain in dysferlin is important for association with MG53 (TRIM72)

In skeletal muscle, Mitsugumin 53 (MG53), also known as muscle-specific tripartite motif 72, reportedly interacts with dysferlin to regulate membrane repair. To better understand the interactions between dysferlin and MG53, we conducted immunoprecipitation (IP) and pull-down assays. Based on IP assays, the C2A domain in dysferlin associated with MG53. MG53 reportedly exists as a monomer, a homodimer, or an oligomer, depending on the redox state. Based on pull-down assays, wild-type dysferlin associated with MG53 dimers in a Ca2+-dependent manner, but MG53 oligomers associated with both wild-type and C2A-mutant dysferlin in a Ca2+-independent manner. In pull-down assays, a pathogenic missense mutation in the C2A domain (W52R-C2A) inhibited the association between dysferlin and MG53 dimers, but another missense mutation (V67D-C2A) altered the calcium sensitivity of the association between the C2A domain and MG53 dimers. In contrast to the multimers, the MG53 monomers did not interact with wild-type or C2A mutant dysferlin in pull-down assays. These results indicated that the C2A domain in dysferlin is important for the Ca2+-dependent association with MG53 dimers and that dysferlin may associate with MG53 dimers in response to the influx of Ca2+ that occurs during membrane injury. To examine the biological role of the association between dysferlin and MG53, we co-expressed EGFP-dysferlin with RFP-tagged wild-type MG53 or RFP-tagged mutant MG53 (RFP-C242A-MG53) in mouse skeletal muscle, and observed molecular behavior during sarcolemmal repair; it has been reported that the C242A-MG53 mutant forms dimers, but not oligomers. In response to membrane wounding, dysferlin accumulated at the injury site within 1 second; this dysferlin accumulation was followed by the accumulation of wild-type MG53. However, accumulation of RFP-C242A MG53 at the wounded site was impaired relative to that of RFP-wild-type MG53. Co-transfection of RFP-C242A MG53 inhibited the recruitment of dysferlin to the sarcolemmal injury site. We also examined the molecular behavior of GFP-wild-type MG53 during sarcolemmal repair in dysferlin-deficient mice which show progressive muscular dystrophy, and found that GFP-MG53 accumulated at the wound similar to wild-type mice. Our data indicate that the coordination between dysferlin and MG53 plays an important role in efficient sarcolemmal repair.