Joohong Ahnn

The DNA sequence of a gene (era) located immediately downstream of the gene (rnc) encoding ribonuclease III of Escherichia coli was determined and found to encode a protein of 316 amino acid residues. The amino acid sequence of this protein, Era, has significant similarity to the yeast RAS proteins. Overexpression of the Era protein was achieved and GTP cross-linking experiments demonstrated that the protein was indeed capable of binding GTP, as are the yeast and mammalian ras gene products. The

Calcineurin (CaN) is a serine/threonine phosphatase, activated by Ca2+/calmodulin (Ca2+/CaM). CaN is known to regulate various cellular responses in different organisms. A recent study showed an extended life span in the calcineurin mutants of C. elegans. In this study, we report that calcineurin defective strains exhibit enhanced autophagy. In addition, we found two essential autophagy genes (bec-1 and atg-7) are required for the life-span extension in calcineurin null mutants [cnb-1(jh103)]. T

Botulinum neurotoxins (BoNTs) have been widely used to treat a variety of clinical ailments associated with pain. The inhibitory action of BoNTs on synaptic vesicle fusion blocks the releases of various pain-modulating neurotransmitters, including glutamate, substance P (SP), and calcitonin gene-related peptide (CGRP), as well as the addition of pain-sensing transmembrane receptors such as transient receptor potential (TRP) to neuronal plasma membrane. In addition, growing evidence suggests that

We have used available chromosomal deficiencies to screen for genetic loci whose zygotic expression is required for formation of body-wall muscle cells during embryogenesis in Caenorhabditis elegans. To test for muscle cell differentiation we have assayed for both contractile function and the expression of muscle-specific structural proteins. Monoclonal antibodies directed against two myosin heavy chain isoforms, the products of the unc-54 and myo-3 genes, were used to detect body-wall muscle di

Thioredoxin, an oxidoreductase, is a multifunction protein. The thioredoxin system is composed of NADPH, thioredoxin reductase and thioredoxin. This enzyme is highly conserved from bacteria to humans. We have characterized TRX-1, a thioredoxin homolog in C. elegans, which has about 36% identity in amino acid sequence with human thioredoxin. By gfp reporter system, trx-1 has been shown to be restrictedly expressed in ASI and ASJ neurons and in intestine. Immunostaining confirmed the intestinal ex

Inorganic pyrophosphatase (PPase) catalyzes the hydrolysis of inorganic pyrophosphate (PPi) into phosphate (Pi), which provides a thermodynamic driving force for important biosynthetic reactions. The nematode Caenorhabditis elegans gene C47E12.4 encodes a PPase (PYP-1) which shows 54% amino acid identity with human PPase. PYP-1 exhibits specific enzyme activity and is mainly expressed in the intestinal and nervous system. A null mutant of pyp-1 reveals a developmental arrest at early larval stag

Thioredoxin reductase (TrxR) is a member of the pyridine nucleotide-disulfide reductase family, which mainly functions in the thioredoxin system. TrxR is found in all living organisms and exists in two major ubiquitous isoenzymes in higher eukaryotic cells; One is cytosolic and the other mitochondrial. Mitochondrial TrxR functions to protect mitochondria from oxidative stress, where reactive oxidative species are mainly generated, while cytosolic TrxR plays a role to maintain optimal oxido-reduc