Intraflagellar transport is essential for spermiogenesis / 中华男科学杂志

Intra flagellar transport (IFT) is an evolutionarily conserved mechanism thought to be essential for the assembly and maintenance of most eukaryotic cilia and flagella. Development of the sperm tail axoneme resembles the cilia formation, which is organized by intraflagellar transport (IFT). Of all mammalian cells, sperm have the longest motile cilia, but few studies are reported on the role of IFT in the formation of sperm flagella and the mechanisms of IFT in spermiogenesis. This article focuses on the role of IFT in spermatogenesis and the importance of IFT in male fertility.

The role of the exocyst in renal ciliogenesis, cystogenesis, tubulogenesis, and development

The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.

Ciliary and Secretory Differentiation of Normal Human Middle Ear Epithelial Cells / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recent technical advances allow serial culture of normal human middle ear epithelial (NHMEE) cells. However, the ciliary differentiation of these cells has not been achieved. The purpose of this study was to establish a culture system to differentiate serially cultured NHMEE cells into ciliated cells. If the ciliated cells were to develop, the percentage of ciliated cells and secretory cells throughout the duration of culture would be measured. We also examined the levels of mucin and lysozyme secretion and their mRNAs in a time-dependent manner. MATERIALS AND METHOD: Normal appearing human middle ear mucosa was harvested and subcultured after enzymatic disaggregation. These cells were differentiated in air-liquid interface (ALI) culture for 2 days, 1 week, 2 weeks, 3 weeks and 4 weeks after confluence. On each culture period, the ratio of ciliated cells and secretory cells and the amount of mucin and lysozyme secreted from the cultured cell were measured by immunohistochemical study and dot blotting. The level of mucin genes 5AC (MUC5AC), MUC5B, MUC8 messenger RNA(mRNA)s and the level of lysozyme mRNA were measured on each culture period by reverse transcription (RT)-polymerase chain reaction (PCR). RESULTS: Ciliogenesis usually started on the 16th-18th day after confluence. The percentage of ciliated cells increased over time up to 10.6% but that of secretory cells remained at about 40% throughout culture duration. By the 14th day after confluence, the amounts of mucin and lysozyme secretion increased rapidly and then maintained a plateau. The expression levels of MUC5B, MUC8 and Lysozyme increased with culture time. Especially, MUC8 showed a dramatic increase on the 28th day after confluence. In contrast, the level of MUC5AC mRNA showed a peak on the 14th day after confluence, and then decreased. CONCLUSION: Ciliary differentiation of NHMEE cells can be induced by ALI culture system. Our study also suggests that secretory function develops earlier than ciliogenesis, and that the expressions of MUC5B and MUC8 mRNAs increase as a function of differentiation.

A Study on Ciliogenesis of Tracheal Epithelium in Human Fetus / 대한해부학회지

Ciliogenesis was investigated in the tracheal epithelium of human fetus at mid trimester of gestation (15~22 weeks), and the substructure of basal body was studied with serial, cross sections. The ciliogenic cells were long columnar cells with an electron -lucent cytoplasm, and contained rich free ribosomes and smooth endoplasmic reticulum. Apical cytoplasm of these cells contained various structures related to ciliogenesis including fibrous granules, procentrioles, centrioles and basal bodies. Basal bodies were located near apical plasma membrane and had basal foot and striated rootlets. In cross section, alar sheets appeared at transitional area between distal portion of basal body and axoneme, and basal foot at distal portion of basal body. Alar sheets arouse from each peripheral triplets of basal body and projected radially clockwise in apex to base view. Basal foot was a cone shaped structure with cross striation which base attached to two or three of the peripheral triplet sets and apex converged to basal foot cap. Three dimentional reconstruction by serial cross section of the basal body showed a structural relationship of alar sheets and basal feet with basal body. By immunohistochemistry, alpha -tubulin label was seen in both basal and surface ciliated cells, and gamma-tubulin label was seen in the apical region of surface cilated cells. These results indicate that ciliogenesis of tracheal epithelium of human fetus is performed mainly by acentriolar ciliogenesis, and suggest the ciliogenesis and ciliary movement at mid trimester of gestation are active.