HAX-1: a family of apoptotic regulators in health and disease.

HAX-1 comprises a family of ubiquitously expressed proteins that play important roles in the regulation of programmed cell death. Herein, we provide a comprehensive review of the expression profile of HAX-1 and its functional implications during health and disease, highlighting its direct involvement in the development of congenital neutropenia and neural abnormalities, when absent, and its contribution to the progression of psoriasis and cancer, when overexpressed. Moreover, we provide new information on the differential expression of the HAX-1 subfamily in three distinct types of epithelial cancers, including breast, skin, and colon.

HAX-1: a multifaceted antiapoptotic protein localizing in the mitochondria and the sarcoplasmic reticulum of striated muscle cells.

HAX-1 comprises a family of ubiquitously expressed proteins with antiapoptotic properties. In the current study, we investigated HAX-1's temporospatial distribution in rat striated muscles during development and in adulthood. In cardiocytes, HAX-1 is organized at the level of Z-disks throughout embryogenesis and adulthood; however, in skeletal myofibers, it is in register with M-bands during embryonic and early postnatal life and Z-disks during late postnatal and adult life.

Muscle giants: molecular scaffolds in sarcomerogenesis.

Myofibrillogenesis in striated muscles is a highly complex process that depends on the coordinated assembly and integration of a large number of contractile, cytoskeletal, and signaling proteins into regular arrays, the sarcomeres. It is also associated with the stereotypical assembly of the sarcoplasmic reticulum and the transverse tubules around each sarcomere. Three giant, muscle-specific proteins, titin (3-4 MDa), nebulin (600-800 kDa), and obscurin (approximately 720-900 kDa), have been proposed to play important roles in the assembly and stabilization of sarcomeres.