Sensitive Fluorescent Biosensor Reveals Differential Subcellular Regulation of PKC.

The protein kinase C (PKC) family of serine/threonine kinases, which consist of three distinctly regulated subfamilies, have long been established as critical for a variety of cellular functions. However, how PKC enzymes are regulated at different subcellular locations, particularly at emerging signaling hubs such as the ER, lysosome, and Par signaling complexes, is unclear. Here, we present a sensitive Excitation Ratiometric (ExRai) C Kinase Activity Reporter (ExRai-CKAR2) that enables the detection of minute changes in subcellular PKC activity. Using ExRai-CKAR2 in conjunction with an enhanced diacylglycerol (DAG) biosensor capable of detecting intracellular DAG dynamics, we uncover the differential regulation of PKC isoforms at distinct subcellular locations. We find that G-protein coupled receptor (GPCR) stimulation triggers sustained PKC activity at the ER and lysosomes, primarily mediated by Ca2+ sensitive conventional PKC (cPKC) and novel PKC (nPKC), respectively, with nPKC showing high basal activity due to elevated basal DAG levels on lysosome membranes. The high sensitivity of ExRai-CKAR2, targeted to either the cytosol or Par-complexes, further enabled us to detect previously inaccessible endogenous atypical PKC (aPKC) activity in 3D organoids. Taken together, ExRai-CKAR2 is a powerful tool for interrogating PKC regulation in response to physiological stimuli.

Endosome positioning coordinates spatially selective GPCR signaling.

G-protein-coupled receptors (GPCRs) can initiate unique functional responses depending on the subcellular site of activation. Efforts to uncover the mechanistic basis of compartmentalized GPCR signaling have concentrated on the biochemical aspect of this regulation. Here we assess the biophysical positioning of receptor-containing endosomes as an alternative salient mechanism. We devise a strategy to rapidly and selectively redistribute receptor-containing endosomes 'on command' in intact cells without perturbing their biochemical composition. Next, we present two complementary optical readouts that enable robust measurements of bulk- and gene-specific GPCR/cyclic AMP (cAMP)-dependent transcriptional signaling with single-cell resolution. With these, we establish that disruption of native endosome positioning inhibits the initiation of the endosome-dependent transcriptional responses. Finally, we demonstrate a prominent mechanistic role of PDE-mediated cAMP hydrolysis and local protein kinase A activity in this process. Our study, therefore, illuminates a new mechanism regulating GPCR function by identifying endosome positioning as the principal mediator of spatially selective receptor signaling.

Clinical Study on the Thoracodorsal Artery Perforator Flap in Breast-Conserving Reconstruction of T2 Breast Cancer.

BACKGROUND: Breast-conserving surgery combined with oncoplastic breast surgery has become the standard surgical treatment for early breast cancer. OBJECTIVE: The purpose of this study was to investigate the safety and efficacy of the thoracodorsal artery perforator flap (TDAPF) in breast-conserving reconstruction of T2 breast cancer. METHODS: Thirty patients with T2 breast cancer admitted to our hospital from January 2019 to December 2020 were enrolled to receive pedicled TDAPF for repairing breast defects after breast-conserving surgery. Intraoperative conditions, postoperative complications, and shape satisfaction after breast reconstruction were recorded. RESULTS: The operation was successfully completed in all 30 patients, with an operation time of 177.77 ± 24.39 min, bleeding of 44.17 ± 7.67 mL, and length of hospital stay of 5.23 ± .97 d. There was no deformity or seroma at the donor site. Breast shape recovered well after operation. After operation, one patient had fat liquefaction in the recipient site, which healed well after wound treatment. The incidence of postoperative complications was 3.33%. Postoperative follow-up lasted 16-28 months, with a median of 22 months. The Breast-Q score for breast satisfaction was 61.83 ± 12.87 at 6 months after operation, compared to 62.07 ± 11.78 before operation (P > .05). CONCLUSIONS: TDAPF, featuring a high survival rate, moderate flap area, fewer postoperative complications, and high satisfaction with breast shape after operation. For east asian women with moderate breast size, TDAPF is a safe, effective choice for repairing defects in breast-conserving surgery for T2 breast cancer.

Midterm follow-up results of a novel technique: Contralateral breast overlapped reconstruction after mastectomy for unilateral breast cancer.

BACKGROUND: The breasts of Oriental women are characterized by an obvious scar constitution and a relatively small mammary gland volume. Thus, plastic surgery, which is now popular in the West, is not suitable for most patients in China, and Chinese surgeons are searching for symmetrical plastic surgery options that are suitable for patients with breast tumors, unilateral breast implants and an obvious scar constitution. METHODS: Between January 2016 and December 2019, 15 patients underwent contralateral breast overlapped reconstruction (COBOR) at the Affiliated Hospital of Putian University. We assessed their clinicopathological data, complications, cosmetic satisfaction and quality of life. RESULTS: The mean age was 41.6 years (range, 31-54 years), the average BMI was 24.36 kg/m2 (range, 20.3-28.4 kg/m2), the most common tumor location was the upper outer quadrant (n = 9), the mean preoperative tumor size was 21.11 mm (range, 7-42 mm), and 4 patients underwent neoadjuvant chemotherapy. The cancer grades and histological types were as follows: G3 nonspecial type (NST), 3 cases; G2 NST, 6 cases; G2 lobular carcinoma, 1 case; and ductal carcinoma in situ (DCIS), 5 cases. The nipple margin was negative in all of these cases. Among them, there was 1 case of poor wound healing caused by subcutaneous fat liquefaction around the incision. In another case, partial nipple necrosis occurred on the affected side due to an insufficient nipple blood supply after the operation and healed after debridement and dressing changes. There were no cases of tumor recurrence during the mean follow-up of 22.53 months (range, 11-47 months). The BREAST-Q scores showed that COBOR provided good patient satisfaction. CONCLUSION: For Oriental patients with small breasts, COBOR, which results in fewer scars, good symmetry and good satisfaction, is an effective and safe surgical method. However, larger studies with longer follow-up periods are needed to obtain more reliable postoperative results.

Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter.

AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But how AMPK activity is regulated at different subcellular locations for precise spatiotemporal control over metabolism is unclear. Here we present a sensitive, single-fluorophore AMPK activity reporter (ExRai AMPKAR), which reveals distinct kinetic profiles of AMPK activity at the mitochondria, lysosome, and cytoplasm. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) results in slower AMPK activity at lysosomes but does not affect the response amplitude at lysosomes or mitochondria, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further identify a mechanism for AMPK activity in the nucleus, which results from cytoplasmic to nuclear shuttling of AMPK. Thus, ExRai AMPKAR enables illumination of the complex subcellular regulation of AMPK signaling.

Protocol for reading and imaging live-cell PKA activity using ExRai-AKAR2.

Fluorescent protein (FP)-based kinase activity biosensors are powerful tools for probing the spatiotemporal dynamics of signaling pathways in living cells. Yet, the limited sensitivity of most kinase biosensors restricts their reliable application in high-throughput detection modalities. Here, we report a protocol for using an ultrasensitive excitation-ratiometric PKA activity reporter, ExRai-AKAR2, to detect live-cell PKA activity via fluorescence microplate reading and epifluorescence microscopy. The high sensitivity of ExRai-AKAR2 is well suited to these high-throughput applications. For complete details on the use and execution of this protocol, please refer to Mehta et al. (2018) andZhang et al., 2021a) .

Signaling Microdomains in the Spotlight: Visualizing Compartmentalized Signaling Using Genetically Encoded Fluorescent Biosensors.

How cells muster a network of interlinking signaling pathways to faithfully convert diverse external cues to specific functional outcomes remains a central question in biology. Through their ability to convert dynamic biochemical activities to rapid and precise optical readouts, genetically encoded fluorescent biosensors have become instrumental in unraveling the molecular logic controlling the specificity of intracellular signaling. In this review, we discuss how the use of genetically encoded fluorescent biosensors to visualize dynamic signaling events within their native cellular context is elucidating the different strategies employed by cells to organize signaling activities into discrete compartments, or signaling microdomains, to ensure functional specificity.

An ultrasensitive biosensor for high-resolution kinase activity imaging in awake mice.

Protein kinases control nearly every facet of cellular function. These key signaling nodes integrate diverse pathway inputs to regulate complex physiological processes, and aberrant kinase signaling is linked to numerous pathologies. While fluorescent protein-based biosensors have revolutionized the study of kinase signaling by allowing direct, spatiotemporally precise kinase activity measurements in living cells, powerful new molecular tools capable of robustly tracking kinase activity dynamics across diverse experimental contexts are needed to fully dissect the role of kinase signaling in physiology and disease. Here, we report the development of an ultrasensitive, second-generation excitation-ratiometric protein kinase A (PKA) activity reporter (ExRai-AKAR2), obtained via high-throughput linker library screening, that enables sensitive and rapid monitoring of live-cell PKA activity across multiple fluorescence detection modalities, including plate reading, cell sorting and one- or two-photon imaging. Notably, in vivo visual cortex imaging in awake mice reveals highly dynamic neuronal PKA activity rapidly recruited by forced locomotion.

Phase Separation of a PKA Regulatory Subunit Controls cAMP Compartmentation and Oncogenic Signaling.

The fidelity of intracellular signaling hinges on the organization of dynamic activity architectures. Spatial compartmentation was first proposed over 30 years ago to explain how diverse G protein-coupled receptors achieve specificity despite converging on a ubiquitous messenger, cyclic adenosine monophosphate (cAMP). However, the mechanisms responsible for spatially constraining this diffusible messenger remain elusive. Here, we reveal that the type I regulatory subunit of cAMP-dependent protein kinase (PKA), RIα, undergoes liquid-liquid phase separation (LLPS) as a function of cAMP signaling to form biomolecular condensates enriched in cAMP and PKA activity, critical for effective cAMP compartmentation. We further show that a PKA fusion oncoprotein associated with an atypical liver cancer potently blocks RIα LLPS and induces aberrant cAMP signaling. Loss of RIα LLPS in normal cells increases cell proliferation and induces cell transformation. Our work reveals LLPS as a principal organizer of signaling compartments and highlights the pathological consequences of dysregulating this activity architecture.

[Incidence of neonatal asphyxia and contributing factors for the develpment of severe asphyxia in Hubei Enshi Tujia and Miao Autonomous Prefecture: a multicenter study].

OBJECTIVE: To investigate the incidence of neonatal asphyxia and possible contributing factors for the development of severe asphyxia in Hubei Enshi Tujia and Miao Autonomous Prefecture, China. METHODS: A total of 16 hospitals in Hubei Enshi Tujia and Miao Autonomous Prefecture were selected as research centers. A retrospective analysis was performed for the clinical data of 22 294 live births in these 16 hospitals from January to December, 2016 to investigate the incidence rate of neonatal asphyxia and possible contributing factors for the development of severe asphyxia. RESULTS: Of the 22 294 neonates born alive, 733 (3.29%) were diagnosed with neonatal asphyxia, among whom 627 had mild asphyxia and 106 had severe asphyxia. The neonates with low maternal education level, maternal anemia during pregnancy, chorioamnionitis, abnormal amniotic fluid, abnormal umbilical cord, placenta previa, placental abruption, Tujia Minority, preterm birth, and low birth weight had a higher incidence of severe asphyxia (P<0.05). CONCLUSIONS: The incidence rate of neonatal asphyxia in Hubei Enshi Tujia and Miao Autonomous Prefecture is higher. Low maternal education level, maternal anemia during pregnancy, chorioamnionitis, abnormal amniotic fluid, abnormal umbilical cord, placenta previa, placental abruption, Tujia Minority, preterm birth, and low birth weight may be related to the development of severe neonatal asphyxia.

Single-fluorophore biosensors for sensitive and multiplexed detection of signalling activities.

Unravelling the dynamic molecular interplay behind complex physiological processes such as neuronal plasticity requires the ability to both detect minute changes in biochemical states in response to physiological signals and track multiple signalling activities simultaneously. Fluorescent protein-based biosensors have enabled the real-time monitoring of dynamic signalling processes within the native context of living cells, yet most commonly used biosensors exhibit poor sensitivity (for example, due to low dynamic range) and are limited to imaging signalling activities in isolation. Here, we address this challenge by developing a suite of excitation ratiometric kinase activity biosensors that offer the highest reported dynamic range and enable the detection of subtle changes in signalling activity that could not be reliably detected previously, as well as a suite of single-fluorophore biosensors that enable the simultaneous tracking of as many as six distinct signalling activities in single living cells.

Sirt3 deficiency impairs neurovascular recovery in ischemic stroke.

AIMS: Sirt3 is one member of the NAD+ -dependent protein deacetylase family and plays crucial roles in diverse aspects of mammalian biological function. Then the role of Sirt3 on ischemia stroke is unknown. METHODS: To examine the effect of Sirt3 on ischemic stroke, we performed transient middle cerebral artery occlusion (tMCAO) in adult male Sirt3 knockout (KO) and wild-type (WT) mice. RESULTS: The level of Sirt3 in infarct region is decreased after ischemic stroke. In addition, we found that Sirt3 KO mice showed worse neurobehavioral outcome compared with WT mice, accompanied by decreased neurogenesis and angiogenesis as shown by the reduction in number of DCX+ /BrdU+ cells, NeuN+ /BrdU+ cells, and CD31+ /BrdU+ cells in the perifocal region during recovery phase after ischemic stroke. Furthermore, Sirt3 deficiency reduced the activation of vascular endothelial growth factor (VEGF), AKT, and extracellular signal-regulated kinases (ERK) signaling pathways. CONCLUSION: Our results indicated that Sirt3 is beneficial to neurovascular and functional recovery following chronic ischemic stroke.

The expression of Egfl7 in human normal tissues and epithelial tumors.

BACKGROUND AND AIMS: To investigate the expression of Egfl7 in normal adult human tissues and human epithelial tumors.
 METHODS: RT-PCR and Western blot were employed to detect Egfl7 expression in normal adult human tissues and 10 human epithelial tumors including hepatocellular carcinoma (HCC), lung cancer, breast cancer, prostate cancer, colorectal cancer, gastric cancer, esophageal cancer, malignant glioma, ovarian cancer and renal cancer. Immunohistochemistry and cytoimmunofluorescence were subsequently used to determine the localization of Egfl7 in human epithelial tumor tissues and cell lines. ELISA was also carried out to examine the serum Egfl7 levels in cancer patients. In addition, correlations between Egfl7 expression and clinicopathological features as well as prognosis of HCC and breast cancer were also analyzed on the basis of immunohistochemistry results.
 RESULTS: Egfl7 was differentially expressed in 19 adult human normal tissues and was overexpressed in all 10 human epithelial tumor tissues. The serum Egfl7 level was also significantly elevated in cancer patients. The increased Egfl7 expression in HCC correlated with vein invasion, absence of capsule formation, multiple tumor nodes and poor prognosis. Similarly, upregulation of Egfl7 in breast cancer correlated strongly with TNM stage, lymphatic metastasis, estrogen receptor positivity, Her2 positivity and poor prognosis. 
 CONCLUSIONS: Egfl7 is significantly upregulated in human epithelial tumor tissues, suggesting Egfl7 to be a potential biomarker for human epithelial tumors, especially HCC and breast cancer.

Dickkopf-1: as a diagnostic and prognostic serum marker for early hepatocellular carcinoma.

BACKGROUND AND AIMS: The aim of the present study was to evaluate serum Dickkopf-1 (Dkk-1) as a marker for early detection of hepatocellular carcinoma (HCC), as well as for prognostic prediction of early HCC after hepatic resection. METHODS: One-hundred and four cases of matched fresh tissue specimens of early HCC and adjacent non-tumorous liver tissue (ANLT) were obtained for RT-PCR, qRT-PCR, western blot and immunohistochemistry assays. Sera were collected from patients with early HCC (n=184), benign liver tumors (n=29), cirrhosis (n=174), non-cirrhotic hepatitis B (n=193), and from healthy individuals (n=202). The levels of Dkk-1 and alpha fetoprotein (AFP) were measured. RESULTS: The Dkk-1 mRNA and protein levels were both upregulated in early HCC. Serum levels of Dkk-1 in patients with early HCC were significantly higher than in the other 4 groups (p<0.001). Dkk-1 had a better sensitivity and accuracy than AFP (p<0.05). More importantly, 73.1% of the patients negative for AFP could be diagnosed with early HCC using Dkk-1. A combination of Dkk-1 and AFP further improved the diagnostic efficacy. Patients with a high serum Dkk-1 level had poorer overall and relapse-free survivals than those with a low Dkk-1 level (p=0.028 and p=0.045, respectively). These results were shown in a testing cohort and confirmed in a validation cohort of patients. Univariable and multivariable Cox regression analyses showed serum Dkk-1 level to be an independent prognostic factor for overall survival. CONCLUSIONS: Our data show that Dkk-1 is a diagnostic and prognostic serologic marker for early HCC.