Cold-inducible RNA-binding protein (Cirp) interacts with Dyrk1b/Mirk and promotes proliferation of immature male germ cells in mice.

Cold-inducible RNA-binding protein (Cirp) was the first cold-shock protein identified in mammals. It is structurally quite different from bacterial cold-shock proteins and is induced in response to mild, but not severe, hypothermia. To clarify the physiological function of Cirp in vivo, we produced cirp-knockout mice. They showed neither gross abnormality nor defect in fertility, but the number of undifferentiated spermatogonia was significantly reduced and the recovery of spermatogenesis was delayed after treatment with a cytotoxic agent, busulfan. Cirp accelerated cell-cycle progression from G0 to G1 as well as from G1 to S phase in cultured mouse embryonic fibroblasts. Cirp directly bound to dual-specificity tyrosine-phosphorylation-regulated kinase 1B (Dyrk1b, also called Mirk) and inhibited its binding to p27, resulting in decreased phosphorylation and destabilization of p27. Cirp did not affect binding of Dyrk1b to cyclin D1 but inhibited phosphorylation of cyclin D1 by Dyrk1b, resulting in cyclin D1 stabilization. In the spermatogonial cell line GC-1spg, suppression of Cirp expression increased the protein level of p27, decreased that of cyclin D1, and decreased the growth rate, which depended on Dyrk1b. Consistent changes in the protein levels of p27 and cyclin D1 as well as the percentage of cells in G0 phase were observed in undifferentiated spermatogonia of cirp-knockout mice. In undifferentiated spermatogonia of wild-type mice, Cirp and Dyrk1b colocalized in the nucleus. Thus, our study demonstrates that Cirp functions to fine-tune the proliferation of undifferentiated spermatogonia by interacting with Dyrk1b.

Extraperitoneal laparoscopic ureterolithotomy in the supine position for impacted ureteral stones.

We describe initial experiences with extraperitoneal laparoscopic ureterolithotomy in the supine position. This method can provide adequate working space without the risk of mechanical bowel injury and nerve stretching specific to the flank position.

[Spontaneous rupture of infected renal cyst presenting sudden onset of right flank distension: a case report].

A 21-year-old woman was referred to our hospital for sudden onset of right flank distension. Ultrasonography, abdominal CT scan and MRI revealed a giant cyst 20 x 11 x 10 cm on the right kidney. Percutaneous puncture of the lesion was performed and fluid was drained. The fluid was yellowish and puriform. Gradually, the drainage fluid creatinine concentration increased. Cystography revealed communication between the lesion and the pyelocalyceal system. The patient underwent drainage for 25 days, causing the cyst to almost fully collapse. No recurrence has been detected in the follow-up for about 1 year. This case is the 38th case of the rupture of a renal cyst reported in the Japanese literature. We reviewed 37 cases of rupture of renal cysts previously reported in Japan.