The Perinuclear ER Scales Nuclear Size Independently of Cell Size in Early Embryos.

Nuclear size plays pivotal roles in gene expression, embryo development, and disease. A central hypothesis in organisms ranging from yeast to vertebrates is that nuclear size scales to cell size. This implies that nuclei may reach steady-state sizes set by limiting cytoplasmic pools of size-regulating components.

Reticulon 4a promotes exocytosis in mammalian cells.

Endoplasmic reticulum (ER) tubules and sheets conventionally correspond to smooth and rough ER, respectively. The ratio of ER tubules-to-sheets varies in different cell types and changes in response to cellular conditions, potentially impacting the functional output of the ER. To directly test whether ER morphology impacts vesicular trafficking, we increased the tubule-to-sheet ratio in three different ways, by overexpressing Rtn4a, Rtn4b, or REEP5.

Altering the levels of nuclear import factors in early Xenopus laevis embryos affects later development.

More than just a container for DNA, the nuclear envelope carries out a wide variety of critical and highly regulated cellular functions. One of these functions is nuclear import, and in this study we investigate how altering the levels of nuclear transport factors impacts developmental progression and organismal size. During early Xenopus laevis embryogenesis, the timing of a key developmental event, the midblastula transition (MBT), is sensitive to nuclear import factor levels.

Emerin induces nuclear breakage in extract and early embryos.

Emerin is an inner nuclear membrane protein often mutated in Emery-Dreifuss muscular dystrophy. Because emerin has diverse roles in nuclear mechanics, cytoskeletal organization, and gene expression, it has been difficult to elucidate its contribution to nuclear structure and disease pathology. In this study, we investigated emerin's impact on nuclei assembled in egg extract, a simplified biochemical system that lacks potentially confounding cellular factors and activities.

Recent advances in understanding nuclear size and shape.

Size and shape are important aspects of nuclear structure. While normal cells maintain nuclear size within a defined range, altered nuclear size and shape are associated with a variety of diseases. It is unknown if altered nuclear morphology contributes to pathology, and answering this question requires a better understanding of the mechanisms that control nuclear size and shape.