Institut De Recherches Cliniques De Montreal

Clinical Research Institute of Montreal

L'institut De Recherches Cliniques De Montreal

Michel Chretien

Nabil G Seidah

Mieczyslaw Marcinkiewicz

Claude Lazure

Gaetan Thibault

Raul Garcia

Marc Cantin

Robert Day

Nabil Seidah

Using RT-PCR and degenerate oligonucleotides derived from the active site residues of subtilisin-kexin-like serine proteinases, we have identified a highly conserved and phylogenetically ancestral human, rat and mouse type-I membrane-bound proteinase called subtilisin-kexin-isozyme-1 (SKI-1). Computer data bank searches reveals that human SKI-1 was previously cloned but with no identified function. A SKI-1 processed fragment is secreted in culture media in a soluble form. In vitro studies suggest that SKI-1 is a Ca-dependent serine proteinase exhibiting a wide pH optimum for cleavage of proBDNF. Peptides mimicking SKI-1 cleavages sites are also disclosed. SKI-1 prosegment has an ex vivo inhibitory effect on SKI-1 activity. The prosegment is also processed and secreted in culture media. One of its fragments is found tightly associated with the SKI-1 soluble form. Therapeutic applications for SKI-1 inhibitors are disclosed.

Mammalian Subtilisin/kexin isozyme SKI-1: a proprotein convertase with a unique cleavage specificity

This invention relates to a novel and seventh member of the subtilisin-kexin family isolated from rat, which has been named rPC7. The rat spleen cDNA has been totally sequenced. A shorter DNA sequence has been obtained for human, which corresponds to a portion of the catalytic region of a human pro-hormone convertase corresponding to the rat pro-hormone convertase. PC7 clearly distinguishes from the other mammalian members of the subtilisin-kexin family. Its tissue distribution is ubiquitous, but its presence is particularly remarkable in lymphoid tissues. It is present in LoVo cells that are able to cleave the HIV gp160 protein into active gp120/gp41 proteins and that are deficient in other effective pro-hormone convertases known up to date. Therefore, it is proposed that PC7 is a good candidate as a maturation enzyme responsible for the conversion of HIV gp160 protein in target CD.sup.+4 cells.

Mammalian pro-hormone convertase

The present invention relates to pro-hormone convertases and polypeptidic fragments thereof, nucleic acids encoding them, recombinant viruses expressing these convertases, polyclonal antibodies directed against the convertases, diagnostic kits for the detection and measurement of the convertase content in cell or tissue lysates, culture media or biological fluids by RIA. Diagnostic kits were also developped for detection or measurement of nucleic acids, preferably mRNAs, in cell or tissue lysates by hybridization. The invention also concerns oligonucleotides useful as probes or as primers for DNA synthesis. These oligonucleotides were included in the diagnostic kits as well as used for the obtention of specific fragments of the convertases which have served, together with native convertases, as antigens for the obtention of antibodies. The convertases were produced by mammalian cell lines transfected with the recombinant viruses and purified on affinity columns which are also an object of the invention. Processes for producing the native convertases, fragments thereof and antibodies are also described and claimed.

Development of research diagnostic and production tools for pro-hormone

Novel peptides in substantially pure form and selected from the group of peptides having the amino acid sequence:

Natriuretic

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Montreal, Canada

Michel Chretien