Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A 2B adenosine receptor-knockout/reporter gene-knock-in (A 2B AR-knockout/reporter gene-knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-a, and a consequent downregulation of IkB-a are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A 2B AR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A 2B AR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A 2B AR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A 2B ARs regulate these processes. Hence, we identify the A 2B AR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target.

Protein kinase casein kinase II (Ck2) is a cyclic-AMP and calcium-independent serine-threonine kinase that is composed of two catalytic subunits (alpha and alpha') and two regulatory beta-subunits. Ck2 is not a casein kinase in vivo, but over 100 substrates are known. The highly conserved amino acid sequences of its subunits and their broad expression suggest that Ck2 may have a fundamental role in cell function. Ck2 has been implicated in DNA replication, regulation of basal and inducible transcription, translation and control of metabolism. The Ck2alpha and Ck2alpha' isoforms (products of the genes Csnk2a1 and Csnk2a2, respectively) are highly homologous, but the reason for their redundancy and evolutionary conservation is unknown. We find here that Csnk2a2 is preferentially expressed in late stages of spermatogenesis, and male mice in which Csnk2a2 has been disrupted are infertile, with oligospermia and globozoospermia ('round-headed' spermatozoa). This is the first demonstration of a unique role for a Ck2 isoform in development. The primary spermatogenic defect in Csnk2a2-/- testis is a specific abnormality of anterior head shaping of elongating spermatids; this is the first defined gene that regulates sperm head morphogenesis. As the germ cells differentiate, they are capable of undergoing chromatin condensation, although many abnormal cells are deleted through apoptosis or Sertoli cell phagocytosis. The few that survive to populate the epididymis exhibit head abnormalities similar to those described in human globozoospermia, thus Csnk2a2 may be a candidate gene for these inherited syndromes.

Protein kinase CK2 (formerly casein kinase II) is a highly conserved and ubiquitous serine/threonine kinase that is composed of two catalytic subunits (CK2␣ and/or CK2␣) and two CK2␤ regulatory subunits. CK2 has many substrates in cells, and key roles in yeast cell physiology have been uncovered by introducing subunit mutations. Gene-targeting experiments have demonstrated that in mice, the CK2␤ gene is required for early embryonic development, while the CK2␣ subunit appears to be essential only for normal spermatogenesis. We have used homologous recombination to disrupt the CK2␣ gene in the mouse germ line. Embryos lacking CK2␣ have a marked reduction in CK2 activity in spite of the presence of the CK2␣ subunit. CK2␣ ؊/؊ embryos die in mid-gestation, with abnormalities including open neural tubes and reductions in the branchial arches. Defects in the formation of the heart lead to hydrops fetalis and are likely the cause of embryonic lethality. Thus, CK2␣ appears to play an essential and uncompensated role in mammalian development.