HuD is an RNA-binding protein that has been shown to induce neuronal differentiation by stabilizing labile mRNAs carrying AU-rich instability elements. Here, we show a novel mechanism of arginine methylation of HuD by coactivator-associated arginine methyltransferase 1 (CARM1) that affected mRNA turnover of p21 cip1/waf1 mRNA in PC12 cells. CARM1 specifically methylated HuD in vitro and in vivo and colocalized with HuD in the cytoplasm. Inhibition of HuD methylation by CARM1 knockdown elongated the p21 cip1/waf1 mRNA half-life and resulted in a slow growth rate and robust neuritogenesis in response to nerve growth factor (NGF). Methylation-resistant HuD bound more p21 cip1/waf1 mRNA than did the wild type, and its overexpression upregulated p21 cip1/waf1 protein expression. These results suggested that CARM1-methylated HuD maintains PC12 cells in the proliferative state by committing p21 cip1/waf1 mRNA to its decay system. Since the methylated population of HuD was reduced in NGF-treated PC12 cells, downregulation of HuD methylation is a possible pathway through which NGF induces differentiation of PC12 cells.

A 41 year‐old man with progressive nodular infiltration of the lung of about 2 years’duration died of cardiac and respiratory failure. Autopsy revealed bilateral multiple pulmonary hyalinizing granulomas (PHGs) diagnosed on the basis of the characteristic dense hyaline collagen bundles with nonspecific inflammatory infiltration. Constrictive pericarditis, retroperitoneal fibrosis, mediastinal fibrosis, fibrous thickening of the peritoneal and pleural surfaces, and fibrosis of soft tissue of the neck, flank, and hepatic hilar region were present, therefore, a diagnosis of systemic idiopathic fibrosis was made. The patient had anti thyroglobulin and anti‐thyroid microsomal antibodies and lymphocytic thyroiditis. The inflammatory process of PHG of the present case was active and the clinical course was progressive. PHG seems to be a lesion belonging to the systemic idiopathic fibrosis complex. Immunologic abnormalities may be related to PHG and systemic idiopathic fibrosis.

Alcoholic liver fibrosis is a relatively common form of alcoholic liver disease in Japan. It is regarded by some investigators as a prodromal stage of alcoholic liver cirrhosis, but little is known about the volumes of the liver and spleen in this disease state. Therefore, liver and spleen volumes were measured by computed tomography in 32 patients with alcoholic liver fibrosis in comparison with 10 healthy volunteers. Patients with alcoholic liver fibrosis were divided into three subgroups (13 of Grade 1, 9 of Grade 2 and 10 of Grade 3) according to the severity of fibrosis. The volume was calculated from the sum of the area measurements of successive transverse sections of the two organs. The liver volume (mean +/- S.D.) in Grade 2 alcoholic liver fibrosis (1,281 +/- 112 cm3) was significantly (p less than 0.01) larger than in healthy volunteers (1,017 +/- 73 cm3) and in Grade 1 (1,090 +/- 157 cm3), and the liver volume in Grade 3 (1,490 +/- 132 cm3) was larger than in Grade 2 (p less than 0.01). The mean volume of hepatocytes estimated by a two-dimensional image analysis system was significantly (p less than 0.05) larger in Grade 3 than in Grade 2, and that in Grade 2 was larger than in Grade 1. The spleen volume in Grade 3 (151 +/- 40 cm3) was significantly (p less than 0.01) larger than in healthy volunteers (86 +/- 26 cm3), Grade 1 (89 +/- 38 cm3) and Grade 2 (68 +/- 19 cm3). The presumed reason for hepatic volume increase would be the ballooning of hepatocytes along with increased fibrotic component.

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