Montserrat Caballero

Altered secretion of a TIGR/MYOC mutant lacking the olfactomedin domain

TIGR/MYOC, a novel 504 amino acids (aa) protein of unknown function, has recently been linked to glaucoma. The protein is both intra- and extracellular and most known mutations map to its C-terminus, an olfactomedin-like domain. To investigate the properties of a TIGR/MYOC peptide lacking this important domain, we constructed a replication-deficient adenovirus with the first 344 aa and over-expressed the truncated protein in primary human trabecular meshwork cells and perfused human anterior segment cultures. The truncated mutant contains the entire N-terminus plus 98 aa of the olfactomedin-like domain. We found that the delivered truncated mutant accumulates inside the cell, reduces secretion of endogenous TIGR/MYOC and induces an increase in outflow facility at 48 h post-infection. Based on these findings, we hypothesize that TIGR/MYOC might have a dual role in trabecular meshwork function. This dual role might be that of an intracellular modulator of vesicular transport as well as that of a secreted protein involved in extracellular matrix conformation. Both functions could have a direct effect in maintaining aqueous humor outflow facility.

Proteasome inhibition by chronic oxidative stress in human trabecular meshwork cells

The pathophysiologic mechanisms leading to the malfunction of the trabecular meshwork (TM)-Schlemms canal (SC) outflow pathway in glaucoma are still unclear. We hypothesize that chronic oxidative stress may contribute to the malfunction of the outflow pathway by impairing the intracellular proteasome system of the cells, decreasing the ability of the tissue to modulate outflow resistance. To study the effects of chronic oxidative stress on proteasome function, primary cultures of human TM cells were incubated under 40% oxygen and proteasome activity was analyzed by measuring the accumulation of enhanced green fluorescent protein fused to a PEST motif. Changes in proteasome content, cellular senescence, and cell viability were also monitored. After 10 days of exposure to chronic oxidative stress, TM cells showed a marked decline in proteasome activity that was associated with premature senescence and decreased cell viability. These results suggest that proteasome failure may be involved in glaucoma pathophysiology.

Epidemiología molecular del virus del sarampión

INTRODUCCION El virus del sarampion (VS) pertenece al genero de los Morbillivirus, que agrupa a los virus del moquillo canino, virus de la peste bovina, virus de los pequenos rumian- tes, morbillivirus de los focidos, y al morbi- llivirus de los delfines. Este genero pertene- ce a la familia de los Paramimviridae, que son virus RNA de una sola cadena de polari- dad negativa (complementaria a los RNA mensajeros) que forma una nucleocapside helicoidal recubierta de membrana de ori- gen celular’. El genoma de los virus salvajes del sa- rampion es una molecula de RNA de 15.984 nucleotidos2, codifica por las proteinas es- tructurales: N (nucleocapsida), P (fosfopro- teina), L (polimerasa), M (matriz), H (hema- glutinina) y F (de fusion) que se incorporan a las particulas viricas, y otras no estructura- les V y C que se encuentran solamente en las celulas infectadas. En la figura 1 se es- quematizan la estructura de virus y sus pro- teinas. El virus de sarampion es un virus de transmision respiratoria que infecta a huma- nos y primates, y del que no se han descrito serotipos.