In vivo imaging reveals a role for Cdc42 in spindle positioning and planar orientation of cell divisions during vertebrate neural tube closure

Kieserman, Esther K.; Wallingford, John B.

doi:10.1242/jcs.042135

Cited by 40 publications

(39 citation statements)

References 61 publications

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“…In our view, the basolateral trafficking (8-10) and de novo lumen formation defects (11) observed in Rab8a-deficient MDCK kidney cell line in vitro could be the direct consequences of abnormal cell division. Furthermore, most if not all polarity regulators within the Cdc42-Par-aPkc complex or its downstream effectors participate in spindle or midbody orientations (22,(32)(33)(34)(35)(36)(37)(38)(39). Taken together, this is consistent with our findings that the cell division defect is the primary cause of epithelial abnormality upon loss of these small GTPases.…”

Section: Figuresupporting

confidence: 91%

Cdc42 and Rab8a are critical for intestinal stem cell division, survival, and differentiation in mice

Sakamori¹,

Das²,

Yu³

et al. 2012

J. Clin. Invest.

121

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The constant self renewal and differentiation of adult intestinal stem cells maintains a functional intestinal mucosa for a lifetime. However, the molecular mechanisms that regulate intestinal stem cell division and epithelial homeostasis are largely undefined. We report here that the small GTPases Cdc42 and Rab8a are critical regulators of these processes in mice. Conditional ablation of Cdc42 in the mouse intestinal epithelium resulted in the formation of large intracellular vacuolar structures containing microvilli (microvillus inclusion bodies) in epithelial enterocytes, a phenotype reminiscent of human microvillus inclusion disease (MVID), a devastating congenital intestinal disorder that results in severe nutrient deprivation. Further analysis revealed that Cdc42-deficient stem cells had cell division defects, reduced capacity for clonal expansion and differentiation into Paneth cells, and increased apoptosis. Cdc42 deficiency impaired Rab8a activation and its association with multiple effectors, and prevented trafficking of Rab8a vesicles to the midbody. This impeded cytokinesis, triggering crypt apoptosis and disrupting epithelial morphogenesis. Rab8a was also required for Cdc42-GTP activity in the intestinal epithelium, where continued cell division takes place. Furthermore, mice haploinsufficient for both Cdc42 and Rab8a in the intestine demonstrated abnormal crypt morphogenesis and epithelial transporter physiology, further supporting their functional interaction. These data suggest that defects of the stem cell niche can cause MVID. This hypothesis represents a conceptual departure from the conventional view of this disease, which has focused on the affected enterocytes, and suggests stem cell-based approaches could be beneficial to infants with this often lethal condition.

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Section: Figuresupporting

confidence: 91%

Cdc42 and Rab8a are critical for intestinal stem cell division, survival, and differentiation in mice

Sakamori¹,

Das²,

Yu³

et al. 2012

J. Clin. Invest.

121

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“…Both of these studies were based on the analysis of fixed sections of the mammary gland. Cell division orientation can be difficult to analyze in 2D in fixed sections, as spindle orientation can rotate extensively during mitosis in vivo (Kieserman and Wallingford, 2009). By contrast, we were able to follow the entire process of mitosis in 3D in real time.…”

Section: Discussionmentioning

confidence: 91%

Developmental stratification of the mammary epithelium occurs through symmetry-breaking vertical divisions of apically positioned luminal cells

2014

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Mammary ducts are elongated during development by stratified epithelial structures, known as terminal end buds (TEBs). TEBs exhibit reduced apicobasal polarity and extensive proliferation. A major unanswered question concerns the mechanism by which the simple ductal epithelium stratifies during TEB formation. We sought to elucidate this mechanism using real-time imaging of growth factorinduced stratification in 3D cultures of mouse primary epithelial organoids. We hypothesized that stratification could result from vertical divisions in either the apically positioned luminal epithelial cells or the basally positioned myoepithelial cells. Stratification initiated exclusively from vertical apical cell divisions, both in 3D culture and in vivo. During vertical apical divisions, only the mother cell retained tight junctions and segregated apical membranes. Vertical daughter cells initiated an unpolarized cell population located between the luminal and myoepithelial cells, similar to the unpolarized body cells in the TEB. As stratification and loss of apicobasal polarity are early hallmarks of cancer, we next determined the cellular mechanism of oncogenic stratification. Expression of activated ERBB2 induced neoplastic stratification through analogous vertical divisions of apically positioned luminal epithelial cells. However, ERBB2-induced stratification was accompanied by tissue overgrowth and acute loss of both tight junctions and apical polarity. Expression of phosphomimetic MEK (MEK1DD), a major ERBB2 effector, also induced stratification through vertical apical cell divisions. However, MEK1DD-expressing organoids exhibited normal levels of growth and retained apicobasal polarity. We conclude that both normal and neoplastic stratification are accomplished through receptor tyrosine kinase signaling dependent vertical cell divisions within the luminal epithelial cell layer. KEY WORDS: Apicobasal polarity, Breast cancer, Epithelial development, Mammary gland, Mouse INTRODUCTIONSimple epithelial cells are characterized by extensive intercellular junctions and strong polarity along the apicobasal axis (Bryant and Mostov, 2008;Zegers et al., 2003). This polarity is manifested both in specialized morphological features, such as apically localized microvilli, and by segregated plasma membrane domains with distinct apical and basolateral polarity proteins (Nelson, 2003;Yeaman et al., RESEARCH ARTICLE 1999). Yet these highly polarized cells emerge during development from less polarized, multilayered embryonic tissues. Early embryonic morphogenesis in the mammary and salivary glands is accomplished by a tissue with lower levels of polarity and adhesion than the mature epithelium in the adult organ (Andrew and Ewald, 2010;Hsu and Yamada, 2010). A fundamental and unresolved question in biology is how epithelial tissues transition between these different states of organization and polarity (Nelson, 2009). These transitions are also of biomedical interest, as epithelial tumors lose apicobasal polarity and simple organi...

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“…At gastrula stages, there are very few cell divisions in which spindles are aligned vertically, i.e. perpendicular to the epithelium (Kieserman and Wallingford, 2009). We observed that PAR-1TA dramatically increased the number of vertical spindles, as is readily apparent from the numerous 'end-on' spindles seen in the planar (xy) view of the PAR-1TA-expressing epithelium (Fig.…”

Section: Research Reportmentioning

confidence: 54%

PAR-1 promotes primary neurogenesis and asymmetric cell divisions via control of spindle orientation

2010

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SUMMARYIn both invertebrate and vertebrate embryonic central nervous systems, deep cells differentiate while superficial (ventricular) epithelial cells remain in a proliferative, stem cell state. The conserved polarity protein PAR-1, which is basolaterally localised in epithelia, promotes and is required for differentiating deep layer cell types, including ciliated cells and neurons. It has recently been shown that atypical protein kinase C (aPKC), which is apically enriched, inhibits neurogenesis and acts as a nuclear determinant, raising the question of how PAR-1 antagonises aPKC activity to promote neurogenesis. Here we show that PAR-1 stimulates the generation of deep cell progeny from the superficial epithelium of the neural plate and that these deep cells have a corresponding (i.e. deep cell) neuronal phenotype. We further show that gain-and loss-of-function of PAR-1 increase and decrease, respectively, the proportion of epithelial mitotic spindles with a vertical orientation, thereby respectively increasing and decreasing the number of cleavages that generate deep daughter cells. PAR-1 is therefore a crucial regulator of the balance between symmetric (two superficial daughters) and asymmetric (one superficial and one deep daughter) cell divisions. Vertebrate PAR-1 thus antagonises the anti-neurogenic influence of apical aPKC by physically partitioning cells away from it in vivo.

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In vivo imaging reveals a role for Cdc42 in spindle positioning and planar orientation of cell divisions during vertebrate neural tube closure

Cited by 40 publications

References 61 publications

Cdc42 and Rab8a are critical for intestinal stem cell division, survival, and differentiation in mice

Cdc42 and Rab8a are critical for intestinal stem cell division, survival, and differentiation in mice

Developmental stratification of the mammary epithelium occurs through symmetry-breaking vertical divisions of apically positioned luminal cells

PAR-1 promotes primary neurogenesis and asymmetric cell divisions via control of spindle orientation

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