LONDON, Sept 4 (Reuters) - * U.S. stock futures pointed to a higher opening on Wall Street on Tuesday, tracking gains in Europe on Monday when the U.S. market was closed for the Labor Day holiday. Futures for the S&P 500, the Dow Jones and the Nasdaq 100 rose 0.2 to 0.4 percent.
* The Institute for Supply Management releases its August manufacturing index at 1400 GMT. Economists expect a reading of 50.0, versus 49.8 in July.
* Xerox Corp and a wholly-owned unit that contracted with the U.S. state of Texas to process dental claim forms are being investigated to see if they helped allow dentists to submit higher-than-required bills under the state's Medicaid system, the Wall Street Journal reported.
* Markit Economics Limited releases the U.S. final Markit Manufacturing PMI for August at 1258 GMT. The index read 51.9 in a preliminary estimate.
* Heckmann said it would buy privately-held environmental services firm Power Fuels for about $380.5 million in cash and shares, to expand the waste water management group's footprint in the Bakken Shale basin, an unconventional oil shale.
* The Commerce Department releases July construction spending numbers at 1400 GMT. Economists forecast a rise of 0.4 percent, a repeat of the June increase.
* U.S. Secretary of State Hillary Clinton has pledged to take a strong message to Beijing this week on the need to calm regional tensions over maritime disputes that have raised broader fears of military friction between the two major Pacific powers.
* European shares fell 0.3 percent on Tuesday, with caution from investors ahead of a European Central Bank (ECB) meeting later this week limiting traders' appetite to buy riskier assets such as equities.
* Moody's Investors Service has changed its outlook on the Aaa rating of the European Union to negative, warning it might downgrade the bloc if it decides to cut the ratings on the EU's four biggest budget backers: Germany, France, UK and Netherlands.
* U.S. stocks rose on Friday after Federal Reserve Chairman Ben Bernanke, expressing "grave concern" for the stagnating U.S. job market, said the central bank was prepared to take further steps to strengthen the economy if necessary.
* The Dow Jones industrial average was up 90.13 points, or 0.69 percent, at 13,090.84. The Standard & Poor's 500 Index was up 7.10 points, or 0.51 percent, at 1,406.58. The Nasdaq Composite Index was up 18.25 points, or 0.60 percent, at 3,066.96.