PTHrP(1-34)-mediated repression of the PHEX gene in osteoblastic cells involves the transcriptional repressor E4BP4.

PHosphate-regulating gene with homology to Endopeptidase on the X chromosome (PHEX) has been identified as the gene mutated in X-linked hypophosphatemia (XLH) syndrome, the most prevalent form of rickets in humans. The predominant expression of PHEX in bones and teeth, and the defective mineralization of these tissues in XLH patients indicate that PHEX is an important regulator of mineralization. Parathyroid hormone (PTH) and PTH-related protein (PTHrP) are known to regulate the expression of numerous genes in osteoblastic cells through activation of the protein kinase A pathway, including repression of PHEX.

A late role for the association of hnRNP A2 with the HIV-1 hnRNP A2 response elements in genomic RNA, Gag, and Vpr localization.

Two cis-acting RNA trafficking sequences (heterogenous ribonucleoprotein A2 (hnRNP A2)-response elements 1 and 2 or A2RE-1 and A2RE-2) have been identified in HIV-1 vpr and gag mRNAs and were found to confer cytoplasmic RNA trafficking in a murine oligodendrocyte assay. Their activities were assessed during HIV-1 proviral gene expression in COS7 cells. Single point mutations that were shown to severely block RNA trafficking were introduced into each of the A2REs.

Identification of Staufen in the human immunodeficiency virus type 1 Gag ribonucleoprotein complex and a role in generating infectious viral particles.

Staufen is a host protein that is selectively incorporated into human immunodeficiency virus type 1 (HIV-1) particles in a poorly defined process that involves the selection of HIV-1 genomic RNA for encapsidation and the activity of its third double-stranded RNA-binding domain (dsRBD3). To better understand this, we characterized its interactions with pr55(Gag), the principal mediator of HIV-1 genomic RNA encapsidation. Chimeric proviruses harboring wild-type or mutant forms of Staufen were expressed in 293T cells.

Sequences downstream of the 5' splice donor site are required for both packaging and dimerization of human immunodeficiency virus type 1 RNA.

Two copies of human immunodeficiency virus type 1 RNA are incorporated into each virus particle and are further converted to a stable dimer as the virus particle matures. Several RNA segments that flank the 5' splice donor site at nucleotide (nt) 289 have been shown to act as packaging signals. Among these, RNA stem-loop 1 (SL1) (nt 243 to 277) can trigger RNA dimerization through a "kissing-loop" mechanism and thus is termed the dimerization initiation site.