Accurate detection of dysmorphic nuclei using dynamic programming and supervised classification

A vast array of pathologies is typified by the presence of nuclei with an abnormal morphology. Dysmorphic nuclear phenotypes feature dramatic size changes or foldings, but also entail much subtler deviations such as nuclear protrusions called blebs. Due to their unpredictable size, shape and intensity, dysmorphic nuclei are often not accurately detected in standard image analysis routines. To enable accurate detection of dysmorphic nuclei in confocal and widefield fluorescence microscopy images, we have developed an automated segmentation algorithm, called Blebbed Nuclei Detector (BleND), which relies on two-pass thresholding for initial nuclear contour detection, and an optimal path finding algorithm, based on dynamic programming, for refining these contours. Using a robust error metric, we show that our method matches manual segmentation in terms of precision and outperforms state-of-the-art nuclear segmentation methods. Its high performance allowed for building and integrating a robust classifier that recognizes dysmorphic nuclei with an accuracy above 95%. The combined segmentation-classification routine is bound to facilitate nucleus-based diagnostics and enable real-time recognition of dysmorphic nuclei in intelligent microscopy workflows

Statins and histone deacetylase inhibitors affect lamin A/C - histone deacetylase 2 interaction in human cells

We recently identified lamin A/C as a docking molecule for human histone deacetylase 2 (HDAC2) and showed involvement of HDAC2-lamin NC complexes in the DNA damage response. We further showed that lamin NC-HDAC2 interaction is altered in Hutchinson-Gilford Progeria syndrome and other progeroid laminopathies. Here, we show that both inhibitors of lamin A maturation and small molecules inhibiting HDAC activity affect lamin NC interaction with HDAC2. While statins, which inhibit prelamin A processing, reduce protein interaction, HDAC inhibitors strengthen protein binding. Moreover, treatment with HDAC inhibitors restored the enfeebled lamin NC-HDAC2 interaction observed in HGPS cells. Based on these results, we propose that prelamin A levels as well as HDAC2 activation status might influence the extent of HDAC2 recruitment to the lamin A/C-containing platform and contribute to modulate HDAC2 activity. Our study links prelamin A processing to HDAC2 regulation and provides new insights into the effect of statins and histone deacetylase inhibitors on lamin NC functionality in normal and progeroid cells

Statins and Histone Deacetylase Inhibitors Affect Lamin A/C – Histone Deacetylase 2 Interaction in Human Cells

We recently identified lamin A/C as a docking molecule for human histone deacetylase 2 (HDAC2) and showed involvement of HDAC2-lamin A/C complexes in the DNA damage response. We further showed that lamin A/C-HDAC2 interaction is altered in Hutchinson-Gilford Progeria syndrome and other progeroid laminopathies. Here, we show that both inhibitors of lamin A maturation and small molecules inhibiting HDAC activity affect lamin A/C interaction with HDAC2. While statins, which inhibit prelamin A processing, reduce protein interaction, HDAC inhibitors strengthen protein binding. Moreover, treatment with HDAC inhibitors restored the enfeebled lamin A/C-HDAC2 interaction observed in HGPS cells. Based on these results, we propose that prelamin A levels as well as HDAC2 activation status might influence the extent of HDAC2 recruitment to the lamin A/C-containing platform and contribute to modulate HDAC2 activity. Our study links prelamin A processing to HDAC2 regulation and provides new insights into the effect of statins and histone deacetylase inhibitors on lamin A/C functionality in normal and progeroid cells

Bypassing border control : nuclear envelope rupture in disease

Recent observations in laminopathy patient cells and cancer cells have revealed that the nuclear envelope (NE) can transiently rupture during interphase. NE rupture leads to an uncoordinated exchange of nuclear and cytoplasmic material, thereby deregulating cellular homeostasis. Moreover, concurrently inflicted DNA damage could prime rupture-prone cells for genome instability. Thus, NE rupture may represent a novel pathogenic mechanism that has far-reaching consequences for cell and organism physiology

Loss of nuclear envelope integrity in aging and disease

The nuclear envelope (NE) serves as a central organizing unit for the eukaryotic cell. By virtue of its highly selective, semipermeable barrier function, the NE shields the enclosed genetic material, while at the same time ensuring its regulated transcription, replication, and repair. The NE has long been considered to only dismantle during mitosis. However, in recent years it has become clear that in a variety of pathologies, NE integrity becomes compromised during interphase as well. Loss of NE integrity, or briefly NE stress, is manifested in various ways, ranging from a gradual reduction in nucleocytoplasmic transport function, to selective loss and degradation of NE components, and finally to catastrophic rupture events that provoke abhorrent molecular fluxes between the nucleus and cytoplasm. Although cells manage to cope with such forms of NE stress, the different insults to nuclear compartmentalization alter gene regulation and jeopardize genome stability. Hence, loss of NE integrity is emerging as a broad-spectrum pathogenic mechanism. In this review, we discuss the relevance of nuclear compartmentalization and the loss thereof in aging and disease development

Statins and histone deacetylase inhibitors affect lamin A/C histone deacetylase 2 interaction in human cells

We recently identified lamin A/C as a docking molecule for human histone deacetylase 2 (HDAC2) and showed involvement of HDAC2-lamin NC complexes in the DNA damage response. We further showed that lamin NC-HDAC2 interaction is altered in Hutchinson-Gilford Progeria syndrome and other progeroid laminopathies. Here, we show that both inhibitors of lamin A maturation and small molecules inhibiting HDAC activity affect lamin NC interaction with HDAC2. While statins, which inhibit prelamin A processing, reduce protein interaction, HDAC inhibitors strengthen protein binding. Moreover, treatment with HDAC inhibitors restored the enfeebled lamin NC-HDAC2 interaction observed in HGPS cells. Based on these results, we propose that prelamin A levels as well as HDAC2 activation status might influence the extent of HDAC2 recruitment to the lamin A/C-containing platform and contribute to modulate HDAC2 activity. Our study links prelamin A processing to HDAC2 regulation and provides new insights into the effect of statins and histone deacetylase inhibitors on lamin NC functionality in normal and progeroid cells

Unsupervised classification of automatically segmented nuclei.

<p>(A) Overview of the morpho-textural feature set that was extracted from 324 segmented nuclei; (B) Heatmap representing the grayscale-coded z-scores of all the features (columns) for all individual nuclei (rows). Hierarchical clustering on this dataset largely, but not completely, separates normal (blue) from dysmorphic (red) nuclei populations as indicated by the dendrogram on the left. (C) Example nuclei that have been correctly or incorrectly clustered. Colored outlines represent the manually assigned class, whereas the colored bar represents the assigned class by clustering (blue: normal and red: dysmorphic nuclei). Numbers link segmentations of selected nuclei to their position in the heatmap; (D) Principal component analysis of the data set yields two distinct but not fully separated clusters for the two classes as illustrated by a bi-plot explaining 42% of the variance. Discrimination of the two groups is predominantly in the direction of PC1; (E) The factor map reveals correlated features in PC space.</p