Growth is one of the fundamental properties of life. In humans defective. growth can lead to various disorders. Understanding the regulation of. growth is important for the understanding and treatment of growth. disorders.. Growth is generally characterised by three factors: an increase in body. size, the growth rate (time required to reach adulthood) and the process of. developmental differentiation. These independent events need to be tightly. regulated and coordinated in order to ensure the successful completion of. growth.. IP3-mediated calcium signalling is implicated in the regulation of growth.. IP3 signalling is mediated by the IP3R, a large channel protein located. within the ER membrane which is encoded by a gene called
itr-1. In C.. elegans this pathway is known to be involved in the regulation of a wide. range of physiological processes such as pharyngeal pumping, defecation,. ovulation and fertility 1,2,3,4.
itr-1 mutants show retarded growth rate,. which does not correlate with the ability of the animals to feed.. To better understand the role of the IP3 signalling in the regulation of. the worm''s growth rate we have used an RNAi screen to test genetic. interactions with a broad range of candidate genes. Approximately 1,200. genes were selected which include genes involved in insulin-like, TGF, EGF,. Wnt, and Notch signalling as well as some metabolic pathways. The RNAi. screen was performed using the temperature sensitive
itr-1 (
sa73) mutant. which has a slow growth rate and is sterile at 250C. We used the growth. rate rather than growth per se to identify suppressors or enhancers of the.
itr-1(
sa73) phenotype. We simultaneously screened for suppression of. sterility to determine if the interactions are specific for the growth rate. phenotype or they are involved in other phenotypes as well. Moreover, a. more detailed analysis of some of the identified genes will be presented in. order to further define genetic interaction with
itr-1, and the conclusions. for any pattern of genetic interaction emerging from the results will be. discussed.. 1. Walker DS et al (2002) Curr Biol. 12: 951-956.. 2. Dal Santo P et al (1999) Cell 98: 757-767.. 3. Espelt MV et al (2005) J Gen Physiol. 126: 379-392.. 4. Gower NJ et al (2005) Mol Biol Cell. 16: 3978-3986.