Molecular mechanism of the induction of metalloproteinases 1 and 3 in human fibroblasts by basic calcium phosphate crystals. Role of calcium-dependent protein kinase C alpha

Synovial fluid basic calcium phosphate (BCP) crystals are common in osteoarthritis and are often associated with destructive arthropathies involving cartilage degeneration. These crystals are mitogenic and induce oncogene expression and matrix metalloproteinase (MMP) synthesis and secretion in human fibroblasts. To date, BCP crystal-elicited signal transduction pathways have not been completely studied. Because protein kinase C (PKC) is known to play an important role in signal transduction, we investigated the participation of this pathway in the BCP crystal induction of MMP-1 and MMP-3 mRNA and protein expressions in human fibroblasts. Using reverse transcription/polymerase chain reaction (RT-PCR) and Northern and Western blotting techniques, we show here that BCP crystal stimulation of MMP-1 and MMP-3 mRNA and protein expressions in human fibroblasts is dependent upon the calcium-dependent PKC signal transduction pathway and that the PKC alpha isozyme is specifically involved in the pathway. We have previously shown that BCP crystal induction of MMP-1 and MMP-3 is also dependent on the p44/42 mitogen-activated protein kinase (p44/42 MAPK) signal transduction pathway. We now show that these two pathways operate independently and seem to complement each other. This leads to our hypothesis that the two pathways initially function independently, ultimately leading to an increase in mitogenesis and MMP synthesis, and may converge downstream of PKC and p44/42 MAPK to mediate BCP crystal-induced cellular responses

Genomic Structure, Evolutionary Origins, and Reproductive Function of a Large Amplified Intrinsically Disordered Protein-Coding Gene on the X Chromosome (Laidx) in Mice

Mouse sex chromosomes are enriched for co-amplified gene families, present in tens to hundreds of copies. Co-amplification of Slx/Slxl1 on the X chromosome and Sly on the Y chromosome are involved in dose-dependent meiotic drive, however the role of other co-amplified genes remains poorly understood. Here we demonstrate that the co-amplified gene family on the X chromosome, Srsx, along with two additional partial gene annotations, is actually part of a larger transcription unit, which we name Laidx. Laidx is harbored in a 229 kb amplicon that represents the ancestral state as compared to a 525 kb Y-amplicon containing the rearranged Laidy. Laidx contains a 25,011 nucleotide open reading frame, predominantly expressed in round spermatids, predicted to encode an 871 kD protein. Laidx has orthologous copies with the rat and also the 825-MY diverged parasitic Chinese liver fluke, Clonorchis sinensis, the likely result of a horizontal gene transfer of rodent Laidx to an ancestor of the liver fluke. To assess the male reproductive functions of Laidx, we generated mice carrying a multi-megabase deletion of the Laidx-ampliconic region. Laidx-deficient male mice do not show detectable reproductive defects in fertility, fecundity, testis histology, and offspring sex ratio. We speculate that Laidx and Laidy represent a now inactive X vs. Y chromosome conflict that occurred in an ancestor of present day mice

A Neofunctionalized X-Linked Ampliconic Gene Family Is Essential for Male Fertility and Equal Sex Ratio in Mice

A common assumption is that genes essential to a species survival must be deeply conserved. Kruger et al. report how two newly acquired X-linked gene families, Slx and Slxl1, evolved from an autosomal single-copy gene, massively duplicated, became essential for male fertility, and mediated the sex ratio of offspring by gene copy-number changes

A Neofunctionalized X-Linked Ampliconic Gene Family Is Essential for Male Fertility and Equal Sex Ratio in Mice

A common assumption is that genes essential to a species survival must be deeply conserved. Kruger et al. report how two newly acquired X-linked gene families, Slx and Slxl1, evolved from an autosomal single-copy gene, massively duplicated, became essential for male fertility, and mediated the sex ratio of offspring by gene copy-number changes