ABSTRACT
Cilium, an organelle with a unique proteome and organization, protruding from the cell surface, generally serves as a force generator and signaling compartment. During ciliogenesis, ciliary proteins are synthesized in cytoplasm and transported into cilia by intraflagellar transport (IFT) particles, where the inner counterparts undergo reverse trafficking. The homeostasis of IFT plays a key role in cilial structure assembly and signaling transduction. Much progress has been made on the mechanisms and functions of IFT; however, recent studies have revealed the involvement of IFT particle subunits in organogenesis and spermatogenesis. In this review, we discuss new concepts concerning the molecular functions of IFT protein IFT25 and how its interactions with other IFT particle subunits are involved in mammalian development and fertility.
Subject(s)
Animals , Male , Biological Transport , Carrier Proteins/metabolism , Cilia/metabolism , Flagella/metabolism , Mammals/metabolism , Organogenesis , Proteins/metabolism , Signal TransductionABSTRACT
Trypanosoma brucei is a protozoan flagellate that causes African sleeping sickness. Flagellar function in this organism is critical for life cycle progression and pathogenesis, however the regulation of flagellar motility is not well understood. The flagellar axoneme produces a complex beat through the precisely coordinated firing of many proteins, including multiple dynein motors. These motors are found in the inner arm and outer arm complexes. We are studying one of the inner arm dynein motors in the T. brucei flagellum: dynein-f. RNAi knockdown of genes for two components of dynein-f: DNAH10, the a heavy chain, and IC138, an intermediate chain, cause severe motility defects including immotility. To determine if motility defects result from structural disruption of the axoneme, we used two different flagellar preparations to carefully examine axoneme structure in these strains using transmission electron microscopy (TEM). Our analysis showed that inner arm dynein size, axoneme structural integrity and fixed central pair orientation are not significantly different in either knockdown culture when compared to control cultures. These results support the idea that immotility in knockdowns affecting DNAH10 or IC138 results from loss of dynein-f function rather than from obvious structural defects in the axoneme.
Subject(s)
Animals , Axoneme/metabolism , Dyneins/chemistry , Trypanosoma brucei brucei/metabolism , Cell Cycle , Cell Movement , Dyneins/metabolism , Flagella/metabolism , Models, Biological , Microscopy, Electron, Transmission/methods , RNA InterferenceABSTRACT
Monoclonal antibodies were raised against pathogenic promastigotes of Leishmania donovani of Indian origin. Among these, one was used for immuno-affinity purification of a 78 kDa membrane protein present in both the amastigote and promastigote forms of the parasite. Results of immunoblot experiments with the anti-78 kDa antibody revealed that the protein was present only in parasites belonging to the L. donovani complex. The expression of the protein was observed to be the same during different phases of growth of the promastigotes. Therefore, the 78 kDa protein is neither stage-specific nor differentially regulated. Surface iodination and subcellular fractionation of the promastigotes indicated that the protein was localized on the cell surface. The 78 kDa protein was found to inhibit the binding of promastigotes to macrophages significantly, suggesting that it may play a role in the process of infection. Thus, here we report the purification of a surface protein of L. donovani of Indian origin, which may play an important role in the process of infection.